Tetracycline and erythromycin resistance among clinical isolates of Branhamella catarrhalis.

We reviewed tetracycline and erythromycin disk diffusion susceptibility of 457 isolates of Branhamella catarrhalis. Four isolates were resistant to tetracycline, with MICs for two available isolates of 16 micrograms/ml. Sixteen isolates were in the moderately susceptible range for erythromycin, with an MIC for one available isolate being greater than 8 micrograms/ml. These are the first tetracycline- and (by MIC) erythromycin-resistant B. catarrhalis isolates reported from the United States.