Beta-lactamase production in recent clinical isolates of Haemophilus influenzae and their susceptibility to cefaclor and other antimicrobial agents

ABSTRACT

The ability of 383 recent clinical isolates of Haemophilus influenzae to produce beta-lactamase was detected by using cefinase discs. It was found that 8% of the isolates elaborate this enzyme. Since cefaclor supposedly is not inactivated by beta-lactamases of H. influenzae, we studied the in vitro activity of this cephalosporin and compared it with other commonly used antimicrobial agents against isolates of H. influenzae from 383 patients at a tertiary care referral hospital in Riyadh, Saudi Arabia. Cefaclor was found to be most active, inhibiting 98% of the isolates tested, followed by amoxycillin/clavulanic acid and gentamicin [95%], chloramphenicol [93%], cephalothin [90%], ampicillin [87%], tetracycline [77%] trimethoprim-sulphamethoxazole [65%] and erythromycin [47%]