Susceptibility of respiratory and urinary pathogens to ceftibuten and other comparative drugs: results of an Italian multicenter survey. The Italian Ceftibuten Study Group.

A survey aimed at assessing the ability of ceftibuten, a new oral third-generation cephalosporin, to eradicate in vitro selected bacterial pathogens was conducted in 1991 in 17 microbiology laboratories evenly distributed in Italy. Over 8700 organisms collected from in- and outpatients affected mainly by respiratory and urinary tract infections were analyzed. This collection of bacteria did not include staphylococci, enterococci, Pseudomonas and other oxidative species naturally refractory to the action of most antibiotics employed. Susceptibility to ceftibuten, cefaclor, cefuroxime, amoxicillin, amoxicillin-clavulanate, cotrimoxazole and erythromycin was assessed using a standardized agar-diffusion method. Production of beta-lactamases was confirmed by the nitrocefin test. Among the microorganisms studied E. coli (32.1%) prevailed, followed by P. mirabilis (17.1%), K. pneumoniae (10.9%), S. pyogenes (6.6%), E. cloacae (5.1%), Serratia spp. (4.5%), Enterobacter spp. (4.2%), H. influenzae (3.6%), S. pneumoniae (2.2%) and M. catarrhalis (2%). Within this group of pathogens amoxicillin resistance, often mediated by synthesis of beta-lactamases, was widely diffused (46.2%). The overall inhibitory activity of the drugs tested decreased as follows: ceftibuten (90.4%), cefuroxime (80.4%), amoxicillin-clavulanate (77.4%), cotrimoxazole (75.3%), cefaclor (72.6%), amoxicillin (53.8%) and erythromycin (32.8%). When the efficacy of the antibiotics was assessed against the collection of respiratory isolates producing beta-lactamases only ceftibuten maintained the same overall potency manifested against the general population while the comparative agents were far less effective. The results of this national survey indicate that, given the low incidence of resistance among the most prevalent causative agents of respiratory and urinary tract infections, ceftibuten can be safely used at present in the empiric therapy of these conditions especially when they occur in community settings.