Statewide survey of the antimicrobial susceptibilities of Haemophilus influenzae producing invasive disease in Tennessee.

Between October 1, 1980, and September 30, 1981, a prospective statewide study of Haemophilus influenzae infections identified 220 culture-proved systemic infections. Of these, 92% were caused by H. influenzae type b. Antimicrobial susceptibility testing of the type b isolates showed that 17% were resistant to ampicillin, but virtually all were susceptible to chloramphenicol, trimethoprim-sulfamethoxazole, cefaclor and rifampin. Ampicillin resistance is common in all parts of Tennessee and chloramphenicol remains the drug of choice for initial therapy of systemic H. influenzae infections.