Clostridium normal flora

Treatment with antibacterial agents alters the normal flora of the colon and may permit overgrowth of Clostridia. Studies indicate that a toxin produced by Clostridium difficile is a primary cause of antibiotic-associated colitis. ... 

The primary goal of therapy in community-acquired pneumonia is to reduce mortality. The secondary goal is to ensure prompt clinical response and symptom resolution with minimum risk of recurrence at an acceptable risk of treatment adverse effects. Other goals include reducing unnecessary disturbance of the patient s normal flora and the associated risk of superinfection with resistant pathogens such as Clostridium difficile. 

Aside from mild or severe allergic reaction, the most commonly experienced cephalosporin toxicities are mild and temporary nausea, vomiting, and diarrhea associated with disturbance of the normal flora. Rarely, a life-threatening pseudomembranous colitis diarrhea associated with the opportunistic and toxin-producing anaerobic pathogen, Clostridium difficile, can be experienced. Rare blood dyscrasias, which can even include aplastic anemia, also are seen. Certain structural types (details below) are associated with prolonged bleeding times and an antabuse-like acute alcohol intolerance. 

Clostridium difficile is a commensal Gram-positive anaerobic bacterium of the human intestine, found in about 2-5% of the population. C. difficile is the most serious cause of antibiotic-associated diarrhoea and can lead to pseudomembranous colitis, a severe infection of the colon, often resulting from eradication of the normal gut flora by antibiotics. Discontinuation of causative antibiotic treatment is often curative. In more serious cases, oral administration of metronidazole or vancomycin is the treatment of choice. The bacterium produces several known toxins, including enterotoxin (toxin A) and cytotoxin (toxin B), both of which are responsible for the diarrhoea and inflammation seen in infected patients another toxin, binary toxin, has also been described. 

Penicillins alter the normal bacterial flora in areas of the body, including the respiratory and intestinal tracts. Patients taking oral penicillins may experience nausea, vomiting, or diarrhea. This is usually of little clinical significance because the normal microflora reestablishes itself quickly after cessation of therapy. However, serious superinfection with resistant organisms such as Pseudomonas, Proteus, or Candida can follow long-term therapy with any penicillin. Superinfection with Clostridium difficile can lead to potentially fatal pseudomembranous colitis. 

The most notable adverse effect associated with clindamycin is antibiotic-associated colitis secondary to toxigenic Clostridium difficile. This organism usually overgrows in the Gl tract in the presence of antibiotics due to the inhibition of normal Gl flora. Ironically, the drug of choice for the treatment of antibiotic-associated colitis is metronidazole. Clindamycin also can cause diarrhea that is not related to C. difficile. 

Florfenicol is associated with producing transient diarrhea in calves and has been associated anecdotally with severe colitis in horses. In one pharmacokinetic study, all of the horses and ponies developed mild diarrhea following i.v., i.m. or p.o. administration of florfenicol. In a recent study where the commercial florfenicol formulation was administered i.m. to horses at 20mg/kg every 48 h, all of the horses remained clinically normal but showed significant changes in commensal fecal flora. High numbers of Clostridium perfringens and Salmonella spp. were isolated from some of the treated horses. Florfenicol should be used with caution in horses because of its potential to induce antimicrobial-associated colitis. 

Clostridium difficile is a Gram-positive bacteria, spore-forming, responsible for 15-20% of the antibiotic-associated diarrhoeas (Hamrick et al. 1989 Eckel et al. 2002). The gold-standard technique for the detection of Clostridium difficile is the stool cytotoxin assay. The microbiological mechanism is related to the production of two toxins (toxins A and B) by Clostridium difficile (Kyne et al. 2000). Disturbance of the normal bacterial flora in the colonic lumen is an important factor for the development of PMC (Ros et al. 1996). Children younger than 1 year develop symptomatic disease probably because of immature enterocytic membrane receptors for the toxin (Ros et al. 1996). 

Clostridium difficile Toxin. Clostridium difficile (C. difficile) is responsible for large numbers of episodes of diarrhea that arise from antibacterial treatment in nosocomial settings (58). Since normal colonic flora inhibit the growth of C. difficile, the outbreak of this disease has been attributed to the disruption of normal... 

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