Staphylococcus Saprophyticus

''Staphylococcus saprophyticus'' is a Gram-positive coccus belonging to the genus ''Staphylococcus''. ''S. saprophyticus'' is a common cause of community-acquired urinary tract infections.

History

''Staphylococcus saprophyticus'' was not recognized as a cause of urinary tract infections until the early 1970s, more than 10 years after its original demonstration in urine specimens. Prior to this, the presence of coagulase-negative staphylococci (CoNS) in urine specimens was dismissed as contamination.

Epidemiology and pathogenesis

In humans, ''S. saprophyticus'' is found in the normal flora of the female genital tract and perineum. It has been isolated from other sources, too, including meat and cheese products, vegetables, the environment, and human and animal gastrointestinal tracts. ''S. saprophyticus'' causes 10–20% of urinary tract infections (UTIs). In females 17–27 years old, it is the second-most common cause of community-acquired UTIs, after ''Escherichia coli''. Sexual activity increases the risk of ''S. saprophyticus'' UTIs because bacteria are displaced from the normal flora of the vagina and perineum into the urethra. Most cases occur within 24 hours of sex, earning this infection the nickname "honeymoon cystitis". ''S. saprophyticus'' has the capacity to selectively adhere to human urothelium. The adhesin for ''S. saprophyticus'' is a lactosamine structure. ''S. saprophyticus'' produces no exotoxins.

Clinical features

Patients with urinary tract infections caused by ''S. saprophyticus'' usually present with symptomatic cystitis. Symptoms include a burning sensation when passing urine, the urge to urinate more often than usual, a 'dripping effect' after urination, weak bladder, a bloated feeling with sharp razor pains in the lower abdomen around the bladder and ovary areas, and razor-like pains during sexual intercourse. Flank pain may occur due to infection of the upper urinary tract, such as pyelonephritis. Signs and symptoms of renal involvement are also often registered.

Laboratory diagnosis

The urine sediment of a patient with a ''S. saprophyticus'' urinary tract infection has a characteristic appearance under the microscope manifesting leukocytes, erythrocytes, and clumping due to cocci adhering to cellular elements. Chemical screening methods for bacteriuria, such as, urine nitrate and glucose do not always detect ''S. saprophyticus'' infection. This is because unlike Gram-negative Enterobacteriaceae urinary tract infections, ''S. saprophyticus'' does not reduce nitrate and has a longer generation time, thus does not consume glucose as rapidly. Even when such an infection occurs above the neck of the bladder, low numbers of colony-forming units (less than 10⁵ cfu/ml) are often present.

''Staphylococcus saprophyticus'' is identified as belonging to the genus ''Staphylococcus'' using the Gram stain and catalase test. It is identitified as a species of coagulase-negative staphylococci (CoNS) using the coagulase test. Lastly, ''S. saprophyticus'' is differentiated from '' S. epidermidis'', another species of pathogenic CoNS, by testing for susceptibility to the antibiotic novobiocin. ''S. saprophyticus'' is novobiocin-resistant, whereas ''S. epidermidis'' is novobiocin-sensitive.

Treatment

''Staphylococcus saprophyticus'' urinary tract infections are usually treated with trimethoprim-sulfamethoxazole or with a quinolone such as to be alone norfloxacin. It has also been shown to be susceptible to ampicillin & ceftriaxone.

The many home remedies or natural treatments for urinary tract infections are not clinically proven, such as cranberry juice, alkalinization, and many types of common herbs and spices. Some show promise, such as to affect the formation of biofilms on surfaces or medical equipment, and in other ''in vitro'' situations.

Different subspecies

Two subspecies of ''S. saprophyticus exist'': ''S. s. bovis'' and ''S. s. saprophyticus'', the latter has colony diameter of > 5mm, and more commonly found in human UTIs. ''S. s. saprophyticus'' is nitrate-reductase negative and pyrrolidonyl-arylamidase negative, while ''S. saprophyticus bovis'' has colony diameter of < 5mm, nitrate-reductase positive and pyrolidonyl-arylamidase positive.

References

External links

Type strain of ''Staphylococcus saprophyticus'' at Bac''Dive'' - the Bacterial Diversity Metadatabase

{{Taxonbar, from=Q1708986

saprophyticus
Gram-positive bacteria
Bacteria described in 1940