Influence of cefaclor, phenethicillin, co-trimoxazole and doxycycine on colonization resistance in healthy volunteers

Abstract

The influence of oral administration of cefaclor, phenethicillin, co-trimoxazole and doxycycline on colonization resistance (CR) of the oropharynx and colon in healthy volunteers was studied. Antimicrobial agents were administered in a randomized cross-over design. No effect on CR of the oropharynx could be demonstrated. Phenethicillin decreased CR of the colon against Enterobacteriaceae (P = 0.001). Co-trimoxazole significantly decreased the concentration of Enterobacteriaceae in faeces (P = 0.03) but the decrease caused by cefaclor and doxycycline did not reach statistical significance. Administration of antimicrobial agents increased the appearance of secondary colonization by Enterobacteriaceae in faeces, especially when Escherichia coli was eliminated. During administration of phenethicillin, secondary colonization occurred at a concentration exceeding 10(7)/g in some volunteers. Following administration of cefaclor, co-trimoxazole and doxycycline, elimination of E. coli may result in the substitution by resistant Gram-negative bacilli in low concentrations.

Host Impairments in Patients with Neoplastic Diseases

“…Some drugs such as aztreonam and imipenem only appear ''friendly'' because they are inactivated by feces [30,40], whereas under the circumstance of diarrhea, parenteral feeding, and gut toxicity, normal stool is no longer produced so these agents may remain sufficiently active to destroy what remains of the colonization resistance. Initially, co-trimoxazole was thought to be neutral [27,34,[41][42][43][44][45], but other evidence suggests otherwise [46]. Individual antibiotics that appear to spare colonization resistance, such as ceftazidime and piperacillin, might have a marked impact when given in combination, leading to an increase in both Clostridium difficile as well as yeasts [47].…”