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A urinary tract infection (UTI) is an
infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...
that affects part of the
urinary tract The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, c ...
. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidney infection (
pyelonephritis Pyelonephritis is inflammation of the kidney, typically due to a bacterial infection. Symptoms most often include fever and flank tenderness. Other symptoms may include nausea, burning with urination, and frequent urination. Complications may ...
). Symptoms from a lower urinary tract infection include pain with
urination Urination, also known as micturition, is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, ...
, frequent urination, and feeling the need to urinate despite having an empty bladder. Symptoms of a kidney infection include
fever Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...
and flank pain usually in addition to the symptoms of a lower UTI. Rarely the urine may appear
bloody ''Bloody'', as an adjective or adverb, is a commonly used expletive attributive in British English, Australian English, Irish English, Indian English and a number of other Commonwealth nations. It has been used as an intensive since at lea ...
. In the very old and the very young, symptoms may be vague or non-specific. The most common cause of infection is ''
Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...
'', though other bacteria or
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
may sometimes be the cause. Risk factors include female anatomy, sexual intercourse,
diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
,
obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...
, and family history. Although sexual intercourse is a risk factor, UTIs are not classified as sexually transmitted infections (STIs).
Kidney infection Pyelonephritis is inflammation of the kidney, typically due to a bacterial infection. Symptoms most often include fever and flank tenderness. Other symptoms may include nausea, burning with urination, and frequent urination. Complications may ...
, if it occurs, usually follows a bladder infection but may also result from a blood-borne infection. Diagnosis in young healthy women can be based on symptoms alone. In those with vague symptoms, diagnosis can be difficult because bacteria may be present without there being an infection. In complicated cases or if treatment fails, a
urine culture Bacteriuria is the presence of bacteria in urine. Bacteriuria accompanied by symptoms is a urinary tract infection while that without is known as asymptomatic bacteriuria. Diagnosis is by urinalysis or urine culture. ''Escherichia coli'' is the ...
may be useful. In uncomplicated cases, UTIs are treated with a short course of
antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
s such as
nitrofurantoin Nitrofurantoin is an antibacterial medication used to treat urinary tract infections, but it is not as effective for kidney infections. It is taken by mouth. Common side effects include nausea, loss of appetite, diarrhea, and headaches. Rarely ...
or
trimethoprim/sulfamethoxazole Trimethoprim/sulfamethoxazole, sold under the brand name Bactrim among others, is a fixed-dose combination antibiotic medication used to treat a variety of bacterial infections. It consists of one part trimethoprim to five parts sulfamethoxa ...
. Resistance to many of the antibiotics used to treat this condition is increasing. In complicated cases, a longer course or intravenous antibiotics may be needed. If symptoms do not improve in two or three days, further diagnostic testing may be needed.
Phenazopyridine Phenazopyridine is a medication which, when excreted by the kidneys into the urine, has a local analgesic effect on the urinary tract. It is often used to help with the pain, irritation, or urgency caused by urinary tract infections, surgery, or ...
may help with symptoms. In those who have bacteria or white blood cells in their urine but have no symptoms, antibiotics are generally not needed, although during pregnancy is an exception. In those with frequent infections, a short course of antibiotics may be taken as soon as symptoms begin or long-term antibiotics may be used as a preventive measure. About 150million people develop a urinary tract infection in a given year. They are more common in women than men, but similar between anatomies while carrying indwelling catheters. In women, they are the most common form of bacterial infection. Up to 10% of women have a urinary tract infection in a given year, and half of women have at least one infection at some point in their lifetime. They occur most frequently between the ages of 16 and 35years. Recurrences are common. Urinary tract infections have been described since ancient times with the first documented description in the Ebers Papyrus dated to c. 1550 BC.


Signs and symptoms

Lower urinary tract infection is also referred to as a bladder infection. The most common symptoms are burning with urination and having to urinate frequently (or an urge to urinate) in the absence of
vaginal discharge Vaginal discharge is a mixture of liquid, cells, and bacteria that lubricate and protect the vagina. This mixture is constantly produced by the cells of the vagina and cervix, and it exits the body through the vaginal opening. The composition, amou ...
and significant pain. These symptoms may vary from mild to severe and in healthy women last an average of sixdays. Some pain above the
pubic bone In vertebrates, the pubic region ( la, pubis) is the most forward-facing ( ventral and anterior) of the three main regions making up the coxal bone. The left and right pubic regions are each made up of three sections, a superior ramus, inferior ...
or in the lower back may be present. People experiencing an upper urinary tract infection, or
pyelonephritis Pyelonephritis is inflammation of the kidney, typically due to a bacterial infection. Symptoms most often include fever and flank tenderness. Other symptoms may include nausea, burning with urination, and frequent urination. Complications may ...
, may experience flank pain,
fever Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...
, or nausea and
vomiting Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteri ...
in addition to the classic symptoms of a lower urinary tract infection. Rarely, the urine may appear
bloody ''Bloody'', as an adjective or adverb, is a commonly used expletive attributive in British English, Australian English, Irish English, Indian English and a number of other Commonwealth nations. It has been used as an intensive since at lea ...
or contain visible pus in the urine. UTIs have been associated with onset or worsening of delirium,
dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...
, and
neuropsychiatric disorder A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitti ...
s such as depression and
psychosis Psychosis is a condition of the mind that results in difficulties determining what is real and what is not real. Symptoms may include delusions and hallucinations, among other features. Additional symptoms are incoherent speech and behavior ...
. The reasons for this are unknown, but may involve a UTI-mediated systemic
inflammatory response Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molecu ...
which affects the brain.
Cytokine Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...
s such as
interleukin-6 Interleukin 6 (IL-6) is an interleukin that acts as both a pro-inflammatory cytokine and an anti-inflammatory myokine. In humans, it is encoded by the ''IL6'' gene. In addition, osteoblasts secrete IL-6 to stimulate osteoclast formation. Smoo ...
produced as part of the inflammatory response may produce
neuroinflammation Neuroinflammation is inflammation of the nervous tissue. It may be initiated in response to a variety of cues, including infection, traumatic brain injury,Ebert SE, Jensen P, Ozenne B, Armand S, Svarer C, Stenbaek DS ''et al.'' Molecular imaging of ...
, in turn affecting dopaminergic and/or
glutamatergic Glutamatergic means "related to glutamate". A glutamatergic agent (or drug) is a chemical that directly modulates the excitatory amino acid (glutamate/aspartate) system in the body or brain. Examples include excitatory amino acid receptor agonis ...
neurotransmission Neurotransmission (Latin: ''transmissio'' "passage, crossing" from ''transmittere'' "send, let through") is the process by which signaling molecules called neurotransmitters are released by the axon terminal of a neuron (the presynaptic neuron), ...
as well as brain
glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...
metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
.


Children

In young children, the only symptom of a urinary tract infection (UTI) may be a fever. Because of the lack of more obvious symptoms, when females under the age of two or uncircumcised males less than a year exhibit a fever, a culture of the urine is recommended by many medical associations. Infants may feed poorly, vomit, sleep more, or show signs of
jaundice Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme meta ...
. In older children, new onset
urinary incontinence Urinary incontinence (UI), also known as involuntary urination, is any uncontrolled leakage of urine. It is a common and distressing problem, which may have a large impact on quality of life. It has been identified as an important issue in geria ...
(loss of bladder control) may occur. About 1 in 400 infants of 1 to 3 months of age with a UTI also have
bacterial meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or ...
.


Elderly

Urinary tract symptoms are frequently lacking in the elderly. The presentations may be vague with incontinence, a change in mental status, or fatigue as the only symptoms, while some present to a health care provider with
sepsis Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...
, an infection of the blood, as the first symptoms. Diagnosis can be complicated by the fact that many elderly people have preexisting incontinence or
dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...
. It is reasonable to obtain a urine culture in those with signs of systemic infection that may be unable to report urinary symptoms, such as when advanced
dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...
is present. Systemic signs of infection include a
fever Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...
or increase in temperature of more than from usual, chills, and an increased white blood cell count.


Cause

Uropathogenic ''E. coli'' from the gut is the cause of 80–85% of community-acquired urinary tract infections, with '' Staphylococcus saprophyticus'' being the cause in 5–10%. Rarely they may be due to viral or
fungal A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...
infections. Healthcare-associated urinary tract infections (mostly related to
urinary catheterization In urinary catheterization a latex, polyurethane, or silicone tube known as a urinary catheter is inserted into the bladder through the urethra to allow urine to drain from the bladder for collection. It may also be used to inject liquids used ...
) involve a much broader range of pathogens including: ''E. coli'' (27%), ''
Klebsiella ''Klebsiella'' is a genus of Gram-negative, oxidase-negative, rod-shaped bacteria with a prominent polysaccharide-based capsule. ''Klebsiella'' species are found everywhere in nature. This is thought to be due to distinct sublineages developi ...
'' (11%), ''
Pseudomonas ''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able t ...
'' (11%), the fungal pathogen ''
Candida albicans ''Candida albicans'' is an opportunistic pathogenic yeast that is a common member of the human gut flora. It can also survive outside the human body. It is detected in the gastrointestinal tract and mouth in 40–60% of healthy adults. It is usu ...
'' (9%), and ''
Enterococcus ''Enterococcus'' is a large genus of lactic acid bacteria of the phylum Bacillota. Enterococci are gram-positive cocci that often occur in pairs (diplococci) or short chains, and are difficult to distinguish from streptococci on physical char ...
'' (7%) among others. Urinary tract infections due to ''
Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive ...
'' typically occur secondary to blood-borne infections. ''
Chlamydia trachomatis ''Chlamydia trachomatis'' (), commonly known as chlamydia, is a bacterium that causes chlamydia, which can manifest in various ways, including: trachoma, lymphogranuloma venereum, nongonococcal urethritis, cervicitis, salpingitis, pelvic infla ...
'' and ''
Mycoplasma genitalium ''Mycoplasma genitalium'' (''MG'', commonly known as Mgen) is a sexually transmitted, small and pathogenic bacterium that lives on the mucous epithelial cells of the urinary and genital tracts in humans. Medical reports published in 2007 and 2 ...
'' can infect the urethra but not the bladder. These infections are usually classified as a
urethritis Urethritis is the inflammation of the urethra. The most common symptoms include painful or difficult urination and urethral discharge. It is a commonly treatable condition usually caused by infection with bacteria. This bacterial infection is oft ...
rather than urinary tract infection.


Intercourse

In young sexually active women, sexual activity is the cause of 75–90% of bladder infections, with the risk of infection related to the frequency of sex. The term "honeymoon cystitis" has been applied to this phenomenon of frequent UTIs during early marriage. In
post-menopausal Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often ...
women, sexual activity does not affect the risk of developing a UTI.
Spermicide Spermicide is a contraceptive substance that destroys sperm, inserted vaginally prior to intercourse to prevent pregnancy. As a contraceptive, spermicide may be used alone. However, the pregnancy rate experienced by couples using only spermicid ...
use, independent of sexual frequency, increases the risk of UTIs. Diaphragm use is also associated. Condom use without spermicide or use of birth control pills does not increase the risk of uncomplicated urinary tract infection.


Sex

Women are more prone to UTIs than men because, in females, the
urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra c ...
is much shorter and closer to the anus. As a woman's estrogen levels decrease with
menopause Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often ...
, her risk of urinary tract infections increases due to the loss of protective
vaginal flora Vaginal flora, vaginal microbiota or vaginal microbiome are the microorganisms that colonize the vagina. They were discovered by the German gynecologist Albert Döderlein in 1892 and are part of the overall human flora. The amount and type of ...
. Additionally, vaginal atrophy that can sometimes occur after menopause is associated with recurrent urinary tract infections. Chronic prostatitis in the forms of
chronic prostatitis/chronic pelvic pain syndrome Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), previously known as chronic nonbacterial prostatitis, is long-term pelvic pain and lower urinary tract symptoms (LUTS) without evidence of a bacterial infection. It affects about 2–6% ...
and
chronic bacterial prostatitis Chronic bacterial prostatitis is a bacterial infection of the prostate gland. It should be distinguished from other forms of prostatitis such as acute bacterial prostatitis and chronic pelvic pain syndrome (CPPS). Signs and symptoms Chronic ba ...
(not acute bacterial prostatitis or
asymptomatic inflammatory prostatitis Asymptomatic inflammatory prostatitis is a painless inflammation of the prostate gland where there is no evidence of infection. It should be distinguished from the other categories of prostatitis characterised by either pelvic pain or evidence ...
) may cause recurrent urinary tract infections in males. Risk of infections increases as males age. While bacteria is commonly present in the urine of older males this does not appear to affect the risk of urinary tract infections.


Urinary catheters

Urinary catheterization In urinary catheterization a latex, polyurethane, or silicone tube known as a urinary catheter is inserted into the bladder through the urethra to allow urine to drain from the bladder for collection. It may also be used to inject liquids used ...
increases the risk for urinary tract infections. The risk of
bacteriuria Bacteriuria is the presence of bacteria in urine. Bacteriuria accompanied by symptoms is a urinary tract infection while that without is known as asymptomatic bacteriuria. Diagnosis is by urinalysis or urine culture. ''Escherichia coli'' is the ...
(bacteria in the urine) is between three and six percent per day and prophylactic antibiotics are not effective in decreasing symptomatic infections. The risk of an associated infection can be decreased by catheterizing only when necessary, using
aseptic technique Asepsis is the state of being free from disease-causing micro-organisms (such as pathogenic bacteria, viruses, pathogenic fungi, and parasites). There are two categories of asepsis: medical and surgical. The modern day notion of asepsis is deri ...
for insertion, and maintaining unobstructed closed drainage of the catheter. Male
scuba divers This is a list of underwater divers whose exploits have made them notable. Underwater divers are people who take part in underwater diving activities – Underwater diving is practiced as part of an occupation, or for recreation, where t ...
using condom catheters and female divers using external catching devices for their
dry suit A dry suit or drysuit provides the wearer with environmental protection by way of thermal insulation and exclusion of water, and is worn by divers, boaters, water sports enthusiasts, and others who work or play in or near cold or contaminated ...
s are also susceptible to urinary tract infections.


Others

A predisposition for bladder infections may run in families. This is believed to be related to genetics. Other risk factors include
diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
, being
uncircumcised Circumcision is a procedure that removes the foreskin from the human penis. In the most common form of the operation, the foreskin is extended with forceps, then a circumcision device may be placed, after which the foreskin is excised. Topic ...
, and having a large prostate. In children UTIs are associated with
vesicoureteral reflux Vesicoureteral reflux (VUR), also known as vesicoureteric reflux, is a condition in which urine flows retrograde, or backward, from the bladder into one or both ureters and then to the renal calyx or kidneys. Urine normally travels in one directio ...
(an abnormal movement of
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellular ...
from the
bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...
into
ureter The ureters are tubes made of smooth muscle that propel urine from the kidneys to the urinary bladder. In a human adult, the ureters are usually long and around in diameter. The ureter is lined by urothelial cells, a type of transitional epit ...
s or
kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...
s) and
constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement ...
. Persons with
spinal cord injury A spinal cord injury (SCI) is damage to the spinal cord that causes temporary or permanent changes in its function. Symptoms may include loss of muscle function, sensation, or autonomic function in the parts of the body served by the spinal cor ...
are at increased risk for urinary tract infection in part because of chronic use of catheter, and in part because of
voiding Urination, also known as micturition, is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, ...
dysfunction. It is the most common cause of infection in this population, as well as the most common cause of hospitalization.


Pathogenesis

The
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
that cause urinary tract infections typically enter the bladder via the urethra. However, infection may also occur via the blood or
lymph Lymph (from Latin, , meaning "water") is the fluid that flows through the lymphatic system, a system composed of lymph vessels (channels) and intervening lymph nodes whose function, like the venous system, is to return fluid from the tissues ...
. It is believed that the bacteria are usually transmitted to the urethra from the bowel, with females at greater risk due to their anatomy. After gaining entry to the bladder, ''E. Coli'' are able to attach to the bladder wall and form a
biofilm A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular ...
that resists the body's immune response. ''Escherichia coli'' is the single most common microorganism, followed by ''Klebsiella'' and ''Proteus'' spp., to cause urinary tract infection. ''Klebsiella'' and ''Proteus'' spp., are frequently associated with stone disease. The presence of Gram positive bacteria such as ''Enterococcus'' and ''Staphylococcus'' is increased. The increased resistance of urinary pathogens to
quinolone antibiotic A quinolone antibiotic is a member of a large group of broad-spectrum bacteriocidals that share a bicyclic core structure related to the substance 4-quinolone. They are used in human and veterinary medicine to treat bacterial infections, as we ...
s has been reported worldwide and might be the consequence of overuse and misuse of quinolones.


Diagnosis

In straightforward cases, a diagnosis may be made and treatment given based on symptoms alone without further laboratory confirmation. In complicated or questionable cases, it may be useful to confirm the diagnosis via
urinalysis Urinalysis, a portmanteau of the words ''urine'' and ''analysis'', is a panel of medical tests that includes physical (macroscopic) examination of the urine, chemical evaluation using urine test strips, and microscopic examination. Macroscopic ...
, looking for the presence of urinary nitrites,
white blood cells White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...
(leukocytes), or
leukocyte esterase Leukocyte esterase (LE) is an esterase (a type of enzyme) produced by leukocytes (white blood cells). A leukocyte esterase test (LE test) is a urinalysis, urine test for the presence of white blood cells and other abnormalities associated with infec ...
. Another test,
urine microscopy Urinalysis, a portmanteau of the words ''urine'' and ''analysis'', is a panel of medical tests that includes physical (macroscopic) examination of the urine, chemical evaluation using urine test strips, and microscopic examination. Macroscopic ...
, looks for the presence of red blood cells, white blood cells, or bacteria. Urine
culture Culture () is an umbrella term which encompasses the social behavior, institutions, and norms found in human societies, as well as the knowledge, beliefs, arts, laws, customs, capabilities, and habits of the individuals in these groups.Tyl ...
is deemed positive if it shows a bacterial colony count of greater than or equal to 103
colony-forming unit In microbiology, colony-forming unit (CFU, cfu or Cfu) is a unit which estimates the number of microbial cells (bacteria, fungi, viruses etc.) in a sample that are viable, able to multiply via binary fission under the controlled conditions. Count ...
s per mL of a typical urinary tract organism. Antibiotic sensitivity can also be tested with these cultures, making them useful in the selection of antibiotic treatment. However, women with negative cultures may still improve with antibiotic treatment. As symptoms can be vague and without reliable tests for urinary tract infections, diagnosis can be difficult in the elderly.


Based on pH

Normal urine pH is slightly acidic, with usual values of 6.0 to 7.5, but the normal range is 4.5 to 8.0. A urine pH of 8.5 or 9.0 is indicative of a urea-splitting organism, such as Proteus, Klebsiella, or Ureaplasma urealyticum; therefore, an asymptomatic patient with a high pH means UTI regardless of the other urine test results. Alkaline pH also can signify struvite kidney stones, which are also known as “infection stones.” Text was copied from this source, which is available under
Creative Commons Attribution 4.0 International License


Classification

A urinary tract infection may involve only the lower urinary tract, in which case it is known as a bladder infection. Alternatively, it may involve the upper urinary tract, in which case it is known as pyelonephritis. If the urine contains significant bacteria but there are no symptoms, the condition is known as
asymptomatic bacteriuria Bacteriuria is the presence of bacteria in urine. Bacteriuria accompanied by symptoms is a urinary tract infection while that without is known as asymptomatic bacteriuria. Diagnosis is by urinalysis or urine culture. ''Escherichia coli'' is th ...
. If a urinary tract infection involves the upper tract, and the person has
diabetes mellitus Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
, is pregnant, is male, or
immunocompromised Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...
, it is considered complicated. Otherwise if a woman is healthy and
premenopausal Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often d ...
it is considered uncomplicated. In children when a urinary tract infection is associated with a fever, it is deemed to be an upper urinary tract infection.


Children

To make the diagnosis of a urinary tract infection in children, a positive urinary culture is required. Contamination poses a frequent challenge depending on the method of collection used, thus a cutoff of 105CFU/mL is used for a "clean-catch" mid stream sample, 104CFU/mL is used for catheter-obtained specimens, and 102CFU/mL is used for suprapubic aspirations (a sample drawn directly from the bladder with a needle). The use of "urine bags" to collect samples is discouraged by the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...
due to the high rate of contamination when cultured, and catheterization is preferred in those not toilet trained. Some, such as the
American Academy of Pediatrics The American Academy of Pediatrics (AAP) is an American professional association of pediatricians, headquartered in Itasca, Illinois. It maintains its Department of Federal Affairs office in Washington, D.C. Background The Academy was founded ...
recommends
renal ultrasound Renal ultrasonography (Renal US) is the examination of one or both kidneys using medical ultrasound. Ultrasonography of the kidneys is essential in the diagnosis and management of kidney-related diseases. The kidneys are easily examined, and most ...
and
voiding cystourethrogram In urology, voiding cystourethrography (VCUG) is a frequently performed technique for visualizing a person's urethra and urinary bladder while the person urinates (voids). It is used in the diagnosis of vesicoureteral reflux (kidney reflux), am ...
(watching a person's urethra and urinary bladder with real time x-rays while they urinate) in all children less than two years old who have had a urinary tract infection. However, because there is a lack of effective treatment if problems are found, others such as the
National Institute for Health and Care Excellence The National Institute for Health and Care Excellence (NICE) is an executive non-departmental public body of the Department of Health and Social Care in England that publishes guidelines in four areas: * the use of health technologies withi ...
only recommends routine imaging in those less than six months old or who have unusual findings.


Differential diagnosis

In women with
cervicitis Cervicitis is inflammation of the uterine cervix. Cervicitis in women has many features in common with urethritis in men and many cases are caused by sexually transmitted infections. Non-infectious causes of cervicitis can include intrauterine ...
(inflammation of the cervix) or
vaginitis Vaginitis, also known as vulvovaginitis, is inflammation of the vagina and vulva. Symptoms may include itching, burning, pain, discharge, and a bad smell. Certain types of vaginitis may result in complications during pregnancy. The three main ...
(inflammation of the
vagina In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen ...
) and in young men with UTI symptoms, a ''
Chlamydia trachomatis ''Chlamydia trachomatis'' (), commonly known as chlamydia, is a bacterium that causes chlamydia, which can manifest in various ways, including: trachoma, lymphogranuloma venereum, nongonococcal urethritis, cervicitis, salpingitis, pelvic infla ...
'' or '' Neisseria gonorrhoeae'' infection may be the cause. These infections are typically classified as a
urethritis Urethritis is the inflammation of the urethra. The most common symptoms include painful or difficult urination and urethral discharge. It is a commonly treatable condition usually caused by infection with bacteria. This bacterial infection is oft ...
rather than a urinary tract infection. Vaginitis may also be due to a
yeast infection Candidiasis is a fungal infection due to any type of '' Candida'' (a type of yeast). When it affects the mouth, in some countries it is commonly called thrush. Signs and symptoms include white patches on the tongue or other areas of the mouth ...
.
Interstitial cystitis Interstitial cystitis (IC), a type of bladder pain syndrome (BPS), is chronic pain in the bladder and pelvic floor of unknown cause. It is the urologic chronic pelvic pain syndrome of women. Symptoms include feeling the need to urinate right aw ...
(chronic pain in the bladder) may be considered for people who experience multiple episodes of UTI symptoms but urine cultures remain negative and not improved with antibiotics.
Prostatitis Prostatitis is an umbrella term for a variety of medical conditions that incorporate bacterial and non-bacterial origin illnesses in the pelvic region. In contrast with the plain meaning of the word (which means "inflammation of the prostate"), the ...
(inflammation of the
prostate The prostate is both an Male accessory gland, accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, ...
) may also be considered in the differential diagnosis.
Hemorrhagic cystitis Hemorrhagic cystitis or haemorrhagic cystitis is an inflammation of the bladder defined by lower urinary tract symptoms that include dysuria, hematuria, and hemorrhage. The disease can occur as a complication of cyclophosphamide, ifosfamide and r ...
, characterized by
blood in the urine Hematuria or haematuria is defined as the presence of blood or red blood cells in the urine. “Gross hematuria” occurs when urine appears red, brown, or tea-colored due to the presence of blood. Hematuria may also be subtle and only detectable w ...
, can occur secondary to a number of causes including: infections,
radiation therapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radi ...
, underlying cancer, medications and toxins. Medications that commonly cause this problem include the
chemotherapeutic agent This is a list of chemotherapeutic agents, also known as cytotoxic agents or cytostatic drugs, that are known to be of use in chemotherapy for cancer. This list is organized by type of agent, although the subsections are not necessarily definitive ...
cyclophosphamide with rates of 2 to 40%.
Eosinophilic cystitis Eosinophilic cystitis is a rare condition where eosinophiles are present in the bladder wall. Signs and symptoms are similar to a bladder infection. Its cause is not entirely clear; however, may be linked to food allergies, infections An infe ...
is a rare condition where
eosinophiles Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells (WBCs) and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. ...
are present in the bladder wall. Signs and symptoms are similar to a bladder infection. Its cause is not entirely clear; however, it may be linked to
food allergies A food allergy is an abnormal immune response to food. The symptoms of the allergic reaction may range from mild to severe. They may include itchiness, swelling of the tongue, vomiting, diarrhea, hives, trouble breathing, or low blood pressur ...
,
infections An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable di ...
, and medications among others.


Prevention

A number of measures have not been confirmed to affect UTI frequency including: urinating immediately after intercourse, the type of underwear used, personal hygiene methods used after urinating or
defecating Defecation (or defaecation) follows digestion, and is a necessary process by which organisms eliminate a solid, semisolid, or liquid waste material known as feces from the digestive tract via the anus. The act has a variety of names ranging f ...
, or whether a person typically bathes or showers. There is similarly a lack of evidence surrounding the effect of holding one's urine,
tampon A tampon is a menstrual product designed to absorb blood and vaginal secretions by insertion into the vagina during menstruation. Unlike a pad, it is placed internally, inside of the vaginal canal. Once inserted correctly, a tampon is held in ...
use, and
douching A douche is a device used to introduce a stream of water into the body for medical or hygienic reasons, or the stream of water itself. Douche usually refers to vaginal irrigation, the rinsing of the vagina, but it can also refer to the rinsing ...
. In those with frequent urinary tract infections who use
spermicide Spermicide is a contraceptive substance that destroys sperm, inserted vaginally prior to intercourse to prevent pregnancy. As a contraceptive, spermicide may be used alone. However, the pregnancy rate experienced by couples using only spermicid ...
or a diaphragm as a method of contraception, they are advised to use alternative methods. In those with
benign prostatic hyperplasia Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the prostate gland. Symptoms may include frequent urination, trouble starting to urinate, weak stream, inability to urinate, or loss o ...
urinating in a sitting position appears to improve bladder emptying which might decrease urinary tract infections in this group. Using urinary catheters as little and as short of time as possible and appropriate care of the catheter when used prevents
catheter-associated urinary tract infection Catheter-associated urinary tract Infection, or CAUTI, is a urinary tract infection associated with urinary catheter use. __TOC__ Core prevention A number of combined practices such as improved hand hygiene, enhanced barrier protection and reduced ...
s. They should be inserted using sterile technique in hospital however non-sterile technique may be appropriate in those who self catheterize. The urinary catheter set up should also be kept sealed. Evidence does not support a significant decrease in risk when silver-alloy catheters are used.


Medications

For those with recurrent infections, taking a short course of antibiotics when each infection occurs is associated with the lowest antibiotic use. A prolonged course of daily antibiotics is also effective. Medications frequently used include
nitrofurantoin Nitrofurantoin is an antibacterial medication used to treat urinary tract infections, but it is not as effective for kidney infections. It is taken by mouth. Common side effects include nausea, loss of appetite, diarrhea, and headaches. Rarely ...
and
trimethoprim/sulfamethoxazole Trimethoprim/sulfamethoxazole, sold under the brand name Bactrim among others, is a fixed-dose combination antibiotic medication used to treat a variety of bacterial infections. It consists of one part trimethoprim to five parts sulfamethoxa ...
. Methenamine is another agent used for this purpose as in the bladder where the acidity is low it produces
formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...
to which resistance does not develop. Some recommend against prolonged use due to concerns of
antibiotic resistance Antimicrobial resistance (AMR) occurs when microbes evolve mechanisms that protect them from the effects of antimicrobials. All classes of microbes can evolve resistance. Fungi evolve antifungal resistance. Viruses evolve antiviral resistance. ...
. In cases where infections are related to intercourse, taking antibiotics afterwards may be useful. In post-menopausal women,
topical A topical medication is a medication that is applied to a particular place on or in the body. Most often topical medication means application to body surfaces such as the skin or mucous membranes to treat ailments via a large range of classes ...
vaginal
estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal acti ...
has been found to reduce recurrence. As opposed to topical creams, the use of vaginal estrogen from
pessaries A pessary is a prosthetic device inserted into the vagina for structural and pharmaceutical purposes. It is most commonly used to treat Stress incontinence, stress urinary incontinence to stop urinary leakage and to treat pelvic organ prolapse to ...
has not been as useful as low dose antibiotics. Antibiotics following short term urinary catheterization decreases the subsequent risk of a bladder infection. A number of
vaccine A vaccine is a biological Dosage form, preparation that provides active acquired immunity to a particular infectious disease, infectious or cancer, malignant disease. The safety and effectiveness of vaccines has been widely studied and verifie ...
s are in development as of 2018.


Children

The evidence that preventive antibiotics decrease urinary tract infections in children is poor. However recurrent UTIs are a rare cause of further kidney problems if there are no underlying abnormalities of the kidneys, resulting in less than a third of a percent (0.33%) of chronic kidney disease in adults. Whether routine circumcision prevents UTIs has not been well studied as of 2011.


Alternative medicine

Some research suggests that
cranberry Cranberries are a group of evergreen dwarf shrubs or trailing vines in the subgenus ''Oxycoccus'' of the genus '' Vaccinium''. In Britain, cranberry may refer to the native species '' Vaccinium oxycoccos'', while in North America, cranberry ...
(juice or capsules) may decrease the number of UTIs in those with frequent infections. A
Cochrane review Cochrane (previously known as the Cochrane Collaboration) is a British international charitable organisation formed to organise medical research findings to facilitate evidence-based choices about health interventions involving health profes ...
concluded that the benefit, if it exists, is small; so did a randomized controlled trial in 2016. Long-term tolerance is also an issue with gastrointestinal upset occurring in more than 30%. Cranberry juice is thus not currently recommended for this indication. As of 2015,
probiotics Probiotics are live microorganisms promoted with claims that they provide health benefits when consumed, generally by improving or restoring the gut microbiota. Probiotics are considered generally safe to consume, but may cause bacteria- host i ...
require further study to determine if they are beneficial. The role of the urinary microbiome in maintaining urinary tract health is not well understood as of 2015. , one review found that taking
mannose Mannose is a sugar monomer of the aldohexose series of carbohydrates. It is a C-2 epimer of glucose. Mannose is important in human metabolism, especially in the glycosylation of certain proteins. Several congenital disorders of glycosylation ...
was as effective as
antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
s to prevent UTIs, while another review found that
clinical trial Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, dietar ...
quality was too low to allow any conclusion about using D‐mannose to prevent or treat UTIs.


Treatment

The mainstay of treatment is
antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
s.
Phenazopyridine Phenazopyridine is a medication which, when excreted by the kidneys into the urine, has a local analgesic effect on the urinary tract. It is often used to help with the pain, irritation, or urgency caused by urinary tract infections, surgery, or ...
is occasionally prescribed during the first few days in addition to antibiotics to help with the burning and urgency sometimes felt during a bladder infection. However, it is not routinely recommended due to safety concerns with its use, specifically an elevated risk of methemoglobinemia (higher than normal level of
methemoglobin Methemoglobin (British: methaemoglobin) (pronounced "met-hemoglobin") is a hemoglobin ''in the form of metalloprotein'', in which the iron in the heme group is in the Fe3+ (ferric) state, not the Fe2+ (ferrous) of normal hemoglobin. Sometimes, it i ...
in the blood).
Paracetamol Paracetamol, also known as acetaminophen, is a medication used to treat fever and mild to moderate pain. Common brand names include Tylenol and Panadol. At a standard dose, paracetamol only slightly decreases body temperature; it is inferior ...
may be used for fevers. There is no good evidence for the use of cranberry products for treating current infections. Fosfomycin can be used as an efficacious treatment for both UTIs and complicated UTIs including acute pyelonephritis. The standard regimen for complicated UTIs is an oral 3g dose administered once every 48 or 72 hours for a total of 3 doses or a 6 grams every 8 hours for 7 days to 14 days when fosfomycin is given in IV form.


Asymptomatic bacteriuria

Those who have bacteria in the urine but no symptoms should not generally be treated with antibiotics. This includes those who are old, those with spinal cord injuries, and those who have urinary catheters. Pregnancy is an exception and it is recommended that women take 7days of antibiotics. If not treated it causes up to 30% of mothers to develop
pyelonephritis Pyelonephritis is inflammation of the kidney, typically due to a bacterial infection. Symptoms most often include fever and flank tenderness. Other symptoms may include nausea, burning with urination, and frequent urination. Complications may ...
and increases risk of
low birth weight Low birth weight (LBW) is defined by the World Health Organization as a birth weight of an infant of or less, regardless of gestational age. Infants born with LBW have added health risks which require close management, often in a neonatal inten ...
and
preterm birth Preterm birth, also known as premature birth, is the birth of a baby at fewer than 37 weeks gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 weeks, very early preterm birth is between 2 ...
. Some also support treatment of those with
diabetes mellitus Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
and treatment before urinary tract procedures which will likely cause bleeding.


Uncomplicated

Uncomplicated infections can be diagnosed and treated based on symptoms alone. Antibiotics taken by mouth such as trimethoprim/sulfamethoxazole, nitrofurantoin, or
fosfomycin Fosfomycin, sold under the brand name Monurol among others, is an antibiotic primarily used to treat lower UTI. It is not indicated for kidney infections. Occasionally it is used for prostate infections. It is generally taken by mouth. Comm ...
are typically first line. Cephalosporins,
amoxicillin/clavulanic acid Amoxicillin/clavulanic acid, also known as co-amoxiclav or amox-clav, sold under the brand name Augmentin, among others, is an antibiotic medication used for the treatment of a number of bacterial infections. It is a combination consisting of a ...
, or a
fluoroquinolone A quinolone antibiotic is a member of a large group of broad-spectrum bacteriocidals that share a bicyclic core structure related to the substance 4-quinolone. They are used in human and veterinary medicine to treat bacterial infections, as wel ...
may also be used. However,
antibiotic resistance Antimicrobial resistance (AMR) occurs when microbes evolve mechanisms that protect them from the effects of antimicrobials. All classes of microbes can evolve resistance. Fungi evolve antifungal resistance. Viruses evolve antiviral resistance. ...
to fluoroquinolones among the bacteria that cause urinary infections has been increasing. The
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
(FDA) recommends against the use of fluoroquinolones, including a
Boxed Warning In the United States, a boxed warning (sometimes "black box warning", colloquially) is a type of warning that appears on the package insert for certain prescription drugs, so called because the U.S. Food and Drug Administration specifies that it ...
, when other options are available due to higher risks of serious side effects, such as
tendinitis Tendinopathy, a type of tendon disorder that results in pain, swelling, and impaired function. The pain is typically worse with movement. It most commonly occurs around the shoulder (rotator cuff tendinitis, biceps tendinitis), elbow (tennis elbo ...
,
tendon rupture Tendon rupture is a condition in which a tendon separates in whole or in part from tissue to which it is attached, or is itself torn or otherwise divided in whole or in part. Examples include: * Achilles tendon rupture * Biceps tendon rupture * A ...
and worsening of myasthenia gravis. These medications substantially shorten the time to recovery with all being equally effective. A three-day treatment with trimethoprim/sulfamethoxazole, or a fluoroquinolone is usually sufficient, whereas nitrofurantoin requires 5–7days. Fosfomycin may be used as a single dose but is not as effective. Fluoroquinolones are not recommended as a first treatment. The
Infectious Diseases Society of America The Infectious Diseases Society of America (IDSA) is a medical association representing physicians, scientists and other health care professionals who specialize in infectious diseases. It was founded in 1963 and is based in Arlington, Virginia. ...
states this due to the concern of generating resistance to this class of medication.
Amoxicillin-clavulanate Amoxicillin/clavulanic acid, also known as co-amoxiclav or amox-clav, sold under the brand name Augmentin, among others, is an antibiotic medication used for the treatment of a number of bacterial infections. It is a combination consisting of a ...
appears less effective than other options. Despite this precaution, some resistance has developed to all of these medications related to their widespread use. Trimethoprim alone is deemed to be equivalent to trimethoprim/sulfamethoxazole in some countries. For simple UTIs, children often respond to a three-day course of antibiotics. Women with recurrent simple UTIs are over 90% accurate in identifying new infections. They may benefit from self-treatment upon occurrence of symptoms with medical follow-up only if the initial treatment fails.


Complicated

Complicated UTIs are more difficult to treat and usually requires more aggressive evaluation, treatment and follow-up. It may require identifying and addressing the underlying complication. Increasing antibiotic resistance is causing concern about the future of treating those with complicated and recurrent UTI.


Pyelonephritis

Pyelonephritis Pyelonephritis is inflammation of the kidney, typically due to a bacterial infection. Symptoms most often include fever and flank tenderness. Other symptoms may include nausea, burning with urination, and frequent urination. Complications may ...
is treated more aggressively than a simple bladder infection using either a longer course of oral antibiotics or intravenous antibiotics. Seven days of the oral fluoroquinolone
ciprofloxacin Ciprofloxacin is a fluoroquinolone antibiotic used to treat a number of bacterial infections. This includes bone and joint infections, intra abdominal infections, certain types of infectious diarrhea, respiratory tract infections, skin inf ...
is typically used in areas where the resistance rate is less than 10%. If the local resistance rates are greater than 10%, a dose of intravenous
ceftriaxone Ceftriaxone, sold under the brand name Rocephin, is a third-generation cephalosporin antibiotic used for the treatment of a number of bacterial infections. These include middle ear infections, endocarditis, meningitis, pneumonia, bone and joint ...
is often prescribed. Trimethoprim/sulfamethoxazole or amoxicillin/clavulanate orally for 14 days is another reasonable option. In those who exhibit more severe symptoms, admission to a hospital for ongoing antibiotics may be needed. Complications such as ureteral obstruction from a
kidney stone Kidney stone disease, also known as nephrolithiasis or urolithiasis, is a crystallopathy where a solid piece of material (kidney stone) develops in the urinary tract. Kidney stones typically form in the kidney and leave the body in the urine s ...
may be considered if symptoms do not improve following two or three days of treatment.


Prognosis

With treatment, symptoms generally improve within 36hours. Up to 42% of uncomplicated infections may resolve on their own within a few days or weeks. Some children will develop recurrent urinary tract infection. When urinary tract infection involves the lower urinary tract, it develop
cystitis A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidney ...
, if urinary tract infection involves the upper tract, pyelonephritis develops. About 10 to 20% of pyelonephritis will go on and develop scarring of the affected kidney. Then, 10 to 20% of those develop scarring will have increased risk of hypertension in later life.


Epidemiology

Urinary tract infections are the most frequent bacterial infection in women. They occur most frequently between the ages of 16 and 35years, with 10% of women getting an infection yearly and more than 40–60% having an infection at some point in their lives. Recurrences are common, with nearly half of people getting a second infection within a year. Urinary tract infections occur four times more frequently in females than males. Pyelonephritis occurs between 20 and 30 times less frequently. They are the most common cause of
hospital-acquired infection A hospital-acquired infection, also known as a nosocomial infection (from the Greek , meaning "hospital"), is an infection that is acquired in a hospital or other health care facility. To emphasize both hospital and nonhospital settings, it is so ...
s accounting for approximately 40%. Rates of asymptomatic bacteria in the urine increase with age from two to seven percent in women of child-bearing age to as high as 50% in elderly women in care homes. Rates of asymptomatic bacteria in the urine among men over 75 are between 7–10%. Asymptomatic bacteria in the urine occurs in 2% to 10% of pregnancies. Urinary tract infections may affect 10% of people during childhood. Among children, urinary tract infections are most common in uncircumcised males less than three months of age, followed by females less than one year. Estimates of frequency among children, however, vary widely. In a group of children with a fever, ranging in age between birth and two years, two to 20% were diagnosed with a UTI.


History

Urinary tract infections have been described since ancient times with the first documented description in the Ebers Papyrus dated to c. 1550 BC. It was described by the Egyptians as "sending forth heat from the bladder". Effective treatment did not occur until the development and availability of antibiotics in the 1930s before which time herbs,
bloodletting Bloodletting (or blood-letting) is the withdrawal of blood from a patient to prevent or cure illness and disease. Bloodletting, whether by a physician or by leeches, was based on an ancient system of medicine in which blood and other bodily flu ...
and rest were recommended.


Pregnancy

Urinary tract infections are more concerning in pregnancy due to the increased risk of kidney infections. During pregnancy, high
progesterone Progesterone (P4) is an endogenous steroid and progestogen sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis of humans and other species. It belongs to a group of steroid hormones called the progestogens and is the m ...
levels elevate the risk of decreased muscle tone of the ureters and bladder, which leads to a greater likelihood of reflux, where urine flows back up the ureters and towards the kidneys. While pregnant women do not have an increased risk of asymptomatic bacteriuria, if bacteriuria is present they do have a 25–40% risk of a kidney infection. Thus if urine testing shows signs of an infection—even in the absence of symptoms—treatment is recommended.
Cephalexin Cefalexin, also spelled cephalexin, is an antibiotic that can treat a number of bacterial infections. It kills gram-positive and some gram-negative bacteria by disrupting the growth of the bacterial cell wall. Cefalexin is a beta-lactam antibi ...
or nitrofurantoin are typically used because they are generally considered safe in pregnancy. A kidney infection during pregnancy may result in
preterm birth Preterm birth, also known as premature birth, is the birth of a baby at fewer than 37 weeks gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 weeks, very early preterm birth is between 2 ...
or
pre-eclampsia Pre-eclampsia is a disorder of pregnancy characterized by the onset of high blood pressure and often a significant amount of protein in the urine. When it arises, the condition begins after 20 weeks of pregnancy. In severe cases of the disease ...
(a state of
high blood pressure Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...
and kidney dysfunction during pregnancy that can lead to
seizure An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with l ...
s). Some women have UTIs that keep coming back in pregnancy. Currently, there is insufficient research on how to best treat these recurrent infections.


References


External links

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