Antimicrobial induced alterations of the human oropharyngeal and intestinal microflora.

Although the role of the normal oropharyngeal and intestinal microflora is not fully understood, there are evidences that alterations in the flora may have serious consequences. The most common and significant cause of disturbances in the normal microflora is the administration of antimicrobial agents. The microflora can be influenced by antimicrobial agents because of incomplete absorption of any orally administered antimicrobial agent, secretion of an antimicrobial agent by the salivary glands or in the bile, or secretion from the intestinal mucosa. In most cases the influence is not beneficial to the patient because suppression of the indigenous microorganisms often permits potential pathogens to overgrow and cause septic conditions, stomatitis, diarrhoea, or colitis. Antimicrobial agents that influence the normal microflora also promote the emergence of antimicrobial-resistant strains. During the recent years, the impact of different antimicrobial agents on the human microflora has been investigated by our research group. Thus the effects on the oropharyngeal and intestinal microflora by peroral administration of penicillin, bacampicillin, erythromycin, clindamycin, doxycycline, nitroimidazole, norfloxacin and ciprofloxacin have been studied. The impact on the microflora by parenteral administration of ampicillin + sulbactam, azlocillin, aztreonam, piperacillin, cefoperazone, cefoxitin, ceftriaxone, moxalactam, imipenem, nitroimidazole and clindamycin has also been investigated. Pronounced changes were observed in the microflora in patients receiving clindamycin, erythromycin, cefoperazone, ceftriaxone and moxalactam, whereas moderate changes were seen in those patients receiving doxycycline, cefoxitin, aztreonam, ampicillin + sulbactam, azlocillin and piperacillin. Penicillin, bacampicillin, imipenem, nitroimidazole, ciprofloxacin and norfloxacin produced only minor changes.(ABSTRACT TRUNCATED AT 250 WORDS)