Invasive Haemophilus influenzae Disease and Antibiotic Susceptibility of Invasive Isolates in Minnesota, 2002-2005

We analyzed susceptibility patterns and β-lactamase production of 184 invasive Haemophilus influenzae disease case isolates that were submitted as part of active laboratory and population-based surveillance over a 4-year period in Minnesota. All ampicillin-resistant isolates produced β-lactamase. Rates of susceptibility to commonly used antimicrobials were high for agents other than ampicillin.