Antibiotic-associated diarrhea (AAD) results from an imbalance in the colonic microbiota caused by

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. Microbiotal alteration changes

carbohydrate metabolism Carbohydrate metabolism is the whole of the biochemistry, biochemical processes responsible for the metabolic anabolism, formation, catabolism, breakdown, and interconversion of carbohydrates in life, living organisms. Carbohydrates are central t ...

with decreased

short-chain fatty acid Short-chain fatty acids (SCFAs) are fatty acids with fewer than six carbon atoms. Derived from intestinal microbial fermentation of indigestible foods, SCFAs are the main energy source of colonocytes, making them crucial to gastrointestinal healt ...

absorption and an

osmotic diarrhea Osmosis (, ) is the spontaneous net movement or diffusion of solvent molecules through a selectively-permeable membrane from a region of high water potential (region of lower solute concentration) to a region of low water potential (region o ...

as a result. Another consequence of antibiotic therapy leading to diarrhea is overgrowth of potentially

pathogenic In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

organisms such as '' Clostridium difficile''. It is defined as frequent loose and watery stools with no other complications. __TOC__

Cause

''Clostridium difficile'', also known more commonly as ''C. diff'', accounts for 10 to 20% of antibiotic-associated diarrhea cases, because the antibiotics administered for the treatment of certain disease processes such as inflammatory colitis also inadvertently kill a large portion of the

gut flora Gut microbiota, gut microbiome, or gut flora, are the microorganisms, including bacteria, archaea, fungi, and viruses that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the gut mi ...

, the

normal flora The human microbiome is the aggregate of all microbiota that reside on or within human tissues and biofluids along with the corresponding anatomical sites in which they reside, including the skin, mammary glands, seminal fluid, uterus, ovarian ...

that is usually present within the

bowel The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...

. With this lower level of "healthy" bacteria present, the overgrowth of ''C. diff'' is then responsible "for elaborating the

enterotoxin An enterotoxin is a protein exotoxin released by a microorganism that targets the intestines. Enterotoxins are chromosomally encoded or plasmid encoded exotoxins that are produced and secreted from several bacterial organisms. They are heat la ...

Treatment

Meta-analyses A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analyses can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting me ...

have concluded that

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 ...

may protect against antibiotic-associated diarrhea in both children and adults. Evidence is insufficient, however, regarding an effect on rates of ''C. difficile'' colitis. Efficacy of probiotic AAD prevention is dependent on the probiotic strain(s) used and on the dosage. Up to a 50% reduction of AAD occurrences has been found. No

side effects In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequence ...

have been reported. Caution is advised when using probiotics in

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 ...

individuals or those who have a compromised intestinal barrier because of the risk of an infection caused by the probiotic supplements.

References

{{Digestive system and abdomen symptoms and signs Diarrhea