In vitro activity of a new broad-spectrum, beta-lactamase-stable oral cephalosporin, cefixime, in comparison with other drugs, against Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis and Streptococcus pneumoniae.

Cefixime, a new orally absorbed iminomethoxyaminothiazolyl cephalosporin, was tested against some microorganisms involved in upper and lower respiratory tract infections such as Haemophilus (influenzae and parainfluenzae), Moraxella catarrhalis and Streptococcus pneumoniae, isolated in the period from November 1990 to April 1991. Its activity was compared to nine other antimicrobial agents: erythromycin, trimethoprim-sulfamethoxazole, ampicillin, amoxicillin-clavulanate, cefaclor, ceftazidime, ceftriaxone, cefotaxime and ofloxacin. Cefixime inhibits 90% of S. pneumoniae, H. influenzae and H. parainfluenzae, both beta-lactamase producers (BLP) or not (NBLP) at concentrations of less than 0.25 mg/l. It inhibits 90% of M. catarrhalis (BLP and NBLP) at concentrations of less than 1 mg/l. In general, cefixime has a superior in vitro activity with respect to cefaclor and the other cephalosporins as well as erythromycin and amoxicillin (the last one in BLP strains). In the evaluation of the antibacterial activity of beta-lactam against Haemophilus and M. catarrhalis, the authors observed different indications in the guidelines for ampicillin. Cefixime is not destroyed by the plasmid-mediated beta-lactamase produced by Haemophilus sp. and M. catarrhalis (TEM and ROB in Haemophilus strains and BRO in M. catarrhalis). In view of its excellent in vitro activity against the commonly encountered respiratory tract pathogens, cefixime is indicated in the therapy of these infections.