Resistance patterns of Haemophilus influenzae

Haemophilus influenzae is an important respiratory tract pathogen, and the prevalence of strains resistant to the antibiotics used to treat it has increased since the 1970s. Data on H. influenzae have been gathered in the Alexander Project, an ongoing, international surveillance study. They reveal that beta-lactamase production is the primary mechanism for H. influenzae resistance and that the resistance has a wide geographical variation, reaching critical levels in some countries. Unlike many techniques used in the past, Alexander Project methods provide accurate, reproducible susceptibility data, allowing the comparison of resistance prevalence over time and between areas. Traditional antimicrobial breakpoints are being superseded by more accurate and clinically relevant methods of predicting drug efficacy, such as time above the MIC, AUC:MIC ratios and pharmacodynamic breakpoints. Continued surveillance for resistance and susceptibility testing of H. influenzae is vital to maximize the benefits of antimicrobial therapy and to contain the spread of infection.