Objectives: To determine the global distribution of TEM-1 and ROB-1 beta-lactamases in Haemophilus influenzae isolated from patients with community-acquired respiratory tract infection during the first 4 years of the PROTEKT study (1999-2003). To investigate the activities of commonly used antibiotics against these isolates.
Methods: For 14 870 H. influenzae, MIC testing was performed using NCCLS broth microdilution methodology. For 2225 beta-lactamase-positive (BLP) H. influenzae, TEM-1 and ROB-1 genes were detected using a Taqman PCR method.
Results: beta-Lactamase positivity was 15.0% overall but varied greatly by country (<5% in several countries to 67.9% in Taiwan). Prevalences of TEM-1 and ROB-1 BLP H. influenzae were 93.7% and 4.6%, respectively, however almost all ROB-1 isolates were found in Canada, the USA and Mexico. ROB-1 isolates (n = 102) were less susceptible against cefaclor (29.4% versus 87.6%) and cefprozil (42.2% versus 91.9%) than TEM-1 (n = 2085) isolates. Differences in susceptibility rates for chloramphenicol, co-trimoxazole and tetracycline were also found between the two groups.
Conclusions: The ROB-1 beta-lactamase was found almost exclusively in North America and was more active against cefaclor and cefprozil than the TEM-1 beta-lactamase.