SUSCEPTIBILITY OF CLINICALLY SIGNIFICANT HAEMOPHILUS-INFLUENZAE STRAINS TO ORAL ANTIMICROBIAL AGENTS USED IN SAUDI-ARABIA

The incidence of beta-lactamase production by Haemophilus influenzae s trains and their susceptibility to commonly used oral antimicrobial ag ents were evaluated. From 1990 to 1992, 600 significant isolates of H. influenzae obtained from various hospitals throughout Saudi Arabia we re identified, serotyped and tested for beta-lactamase production usin g cefinase discs and susceptibility to various antibiotics using the a gar dilution method. The study revealed that 17% of the strains produc ed beta-lactamase; 21% of them were type b. The overall level of resis tance was 30% to erythromycin, 28% to tetracycline,;14.3% to co-trimox azole, 6.6% to chloramphenicol, 1.8% to amoxicillin-clavulanate and 1. 5% to cefaclor. About 1.3% of the strains that did not produce beta-la ctamase were resistant to ampicillin. Resistance of H. influenzae to a ntibiotics is increasing and in several parts of the world resistance to ampicillin has reached substantial levels particularly in type b st rains. Information on resistance is needed for the appropriate selecti on of initial empiric therapy among patients in whom H. influenzae is a suspected pathogen.