Colonization resistance

Antibiotics alter the normal colonic flora, leading to loss of colonization resistance, which is the ability of the normal flora to protect against overgrowth of pathogens, especially when the anaerobic flora are depleted [15], In CDAD, the altered colonization resistance can allow for the overgrowth of C. difficile in the colon. The bacteria produces two toxins which cause disease (toxin A, an enterotoxin, and toxin B, a cytotoxin). The toxins of C. difficile inactivate Rho proteins, which results in the loss of cytoskeletal integrity in enterocytes. Cellular damage results in fluid loss, exudation and diarrhea. The most severe form of C. difficile diarrhea is pseudomembranous colitis, which can cause severe colitis, toxic colon and rarely colon perforation and death. 

In general, these high-risk antibiotics cause less suppression of aerobic bacteria. Decreases in aerobes appear to have less effect on colonization resistance (table 3). Interestingly, colonic lavage without antibiotics decreases colonic bacterial counts by log 2 [40]. 

Van der Waaij D Colonization resistance of the digestive tract - mechanism and clinical consequences. Nahrung 1987 81 507—517. 

Van den Bogaard AE, Weidema WF, van Bo-ven CP, van der Waay D Recolonization and colonization resistance of the large bowel after three methods of preoperative preparation of the gastrointestinal tract for elective colorectal surgery. J Hyg(Lond) 1986 97 49-59. 

Nord CE, Kager L, Malmborg AS Effects of antimicrobial prophylaxis on colonization resistance. J Elosp Infect 1988 1 l(suppl A) 259-264. 

Colonization resistance—Preservation of anaerobic flora by selective gut decontamination to prevent colonization by potentially pathogenic gram-negative organisms. 

Baquero F, Asensio C (1979) In van der Waaij D, Verhoef J (eds) New criteria for antimicrobial therapy maintenance of digestive tract colonization resistance. Exerpta Medica, Amsterdam, p 90... 

Van Saene JJM, Van Saene HFK, Geitz JN, Tarko-Smit NJP, Lerk CF. Quinolones eind colonization resistance in human volunteers. Pharm Weekbl Sci Ed 1986 8 67-71. 

Selective decontamination of the digestive tract is based on the concept of colonization resistance. Studies in mice revealed that the autochthonous intestinal flora protects against colonization with exogenous flora... 

The mode of action of these probiotic strains is hkely to be a fortification of the compromised gut microflora, thus restoring colonization resistance and/or direct inhibitory effects against the diarrhoea-causing pathogen. Probiotic strains have been shown to inhibit pathogenic bacteria both in vitro and in vivo in animal models through a number of different mechanisms (Paubert-Braquet etal. 1995 Asahara etal. 2001 Likotrafiti etal. 

Payne, S., Gibson, G., Wynne, A. etal. (2003) 7 vitro studies on colonization resistance of the human gut microbiota to Candida albicans and the effects of tetracycline and Lactobacillus plantarum LPK. Curr. Issues Intest. Microbiol, 4,1-8. 

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