BETA-LACTAM THERAPY AND INTESTINAL FLORA

Betalactams, mainly when orally administered, may lead to intestinal f lora modifications related to their spectrum of activity, rate of abso rption and degradation. Therefore it is important to investigate the p ossible influence of recently developed oral cephem derivatives on nor mal human microflora. We have investigated the impact on normal human intestinal flora in a 10-day course with cefetamet-pivoxil (GET, 500 m g BID) in comparison to cefixime (CFX, 400 mg qD) or cefuroxime axetil (CA, 250 mg BID) in 24 patients suffering from acute exacerbation of chronic bronchitis. Stool specimens were taken before (day 0), at the end (day 10) and 14 days after treatment (day 24) and qualiquantitativ e microflora composition was determined with a detection limit of 10 C FU/g dry weight. Treatment with CET caused slight and non-significant modifications of normal intestinal nora. On the contrary CF?I and CA s ignificantly affected Enterobacteriaceae and clostridia with a concomi tant increase in enterococci for CFX. With both CFX and CA there was a new appearance of Salmonella spp. as well as Clostridium difficile in 4 and 2 cases, respectively. Therefore CET seems to affect normal bow el nora minimally in comparison to other oral cephalosporins. This asp ect might contribute to the low incidence of GI related side effects i n patients treated with CET for longer than 1 week.