Sensitivity of Haemophilus influenzae to antibiotics.

The use of many different antibiotics to treat chest infection has led us to test the sensitivity of 68 strains of Haemophilus influenzae to 15 different compounds. These included established compounds such as ampicillin and tetracycline and newer agents such as cephalosporins and clindamycin. The minimum inhibitory concentrations of the compounds for H. influenzae were then compared with blood levels attained after the usual dose regimens. There has been a significant increase in tetracycline resistance in the last few years, but all strains were sensitive to ampicillin, chloramphenicol, sulphamethoxazole, and trimethoprim, Several antibiotics were found to be microbiologically unsuitable for treating H. influenzae infections.