Impact of cefaclor on the normal human oropharyngeal and intestinal microflora

Cefaclor was given orally in doses of 250 mg every 8 h for 7 days to 10 volunteers. Saliva and faecal specimens were taken up to 16 days for cultivation of aerobic and anaerobic microorganisms and for assay of cefaclor. Cefaclor was not detected in saliva or faeces. In the oropharynx only minor changes in the anaerobic part of the microflora were observed. The microflora was normalized within 1 week after the administration of cefaclor had stopped. The aerobic intestinal microflora was unchanged during and after cefaclor administration while a minor impact on the anaerobic intestinal microflora was observed. The anaerobic intestinal flora returned to its normal state within 1 week. No new colonization with cefaclor resistant microorganisms were observed and no side effects were registered during the investigation period.