Decreasing prevalence of β-lactamase production among respiratory tract isolates of Haemophilus influenzae in the United States

A total of 986 isolates of Haemophilus influenzae from patients with respiratory tract infections in 45 United States medical centers were characterized during the winter of 2002-2003. beta-Lactamase production was noted with 26.2% of isolates; 14.6% were resistant to trimethoprim-sulfamethoxazole. Resistance to other relevant antimicrobial agents was extremely uncommon. In comparison to the results of four previous national surveys conducted since 1994, the prevalence of beta-lactamase production with this pathogen appears to be decreasing.