Interaction between Antimicrobial Agents and the Oropharyngeal and Intestinal Normal Microflora

Abstract

The present knowledge of the impact of antimicrobial agents on the oropharyngeal and intestinal microflora and the optimal performance of such studies are discussed in this chapter. Disturbances in the oropharyngeal microflora are caused by administration of antimicrobial agents that reach high concentrations in oral tissues. Studies on the impact of antimicrobial agents on the normal microflora should be performed as comparative double-blind studies. Data on the impact of penicillins, cephalosporin, macrolides, ketolides, lincosamides, tetracyclines, nitroimidazoles and quinolones on the oropharyngeal microflora are summarized, as also the influence of monobactams, carbapenems, glycopeptides and streptogramins on the intestinal microflora. Knowledge about the interaction between antimicrobial agents and the normal microflora gives the clinician the possibility to choose agents associated with lesser degrees of ecological disturbances. Consequently, the risk of development of resistant strains and transfer of resistance elements between microorganisms is reduced. Further, consideration of the ecological consequences is also an important step to prevent distribution of resistant strains between patients in hospital settings. Individual pharmacokinetic variations as well as the character of composition and susceptibility of the normal microflora are variables that further influence the interactions.