Antibiotic resistance and prevalence of beta-lactamase in Haemophilus influenzae isolates - a surveillance study of patients with respiratory infection in Saudi Arabia

Haemophillus influenzae was isolated from patients with respiratory tract i nfections in five centers in Saudi Arabia. All of the 129 isolates tested-b y MIC agar dilution were fully susceptible to ceftazidime and ciprofloxacin but 13.2% were resistant to ampicillin, 7% to tetracycline, 5.4% to chlora mphenicol, 3.9% to roxithromycin, and 1.6% to amoxicillin/clavulanic acid. Seventeen (13.2%) of all isolates produced TEM-1 type beta-lactamase, the m ajority (82%) characterized as biotype I or II with 4 (23.5%) encapsulated and belonging to serotype b. There was a clear distinction between the prev alence of beta-lactamase production in hospital patients (26.3% of 19 isola tes) compared with community based patients (10.9% of 110 isolates). In add ition, we report an increase in the prevalence of beta-lactamase negative, ampicillin intermediate strains (BLNAI) compared to previous studies in thi s defined geographical region. Changes in the frequency and nature of antim icrobial resistance in common respiratory pathogens confirms the need to ma intain surveillance. (C) 2000 Elsevier Science Inc. All rights reserved.