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.