The increasing problems with multidrug resistance in relation to
Corynebacterium
, including
C. diphtheriae, are examples of challenges confronting many countries. For this reason, Brazilian
C. diphtheriae strains were evaluated by the E-Test for their susceptibility to nine antibacterial drugs used in therapy. Resistance (MIC < 0.002; 0.38 µg/ml) to penicillin G was found in 14.8% of the strains tested. Although erythromycin (MIC
90 0.75 µg/ml) and azithromycin (MIC
90 0.064 µg/ml) were active against
C. diphtheriae in this study, 4.2% of the strains showed decreased susceptibility (MIC 1.0 µg/ml) to erythromycin. Multiple resistance profiles were determined by the disk diffusion method using 31 antibiotics. Most
C. diphtheriae strains (95.74%) showed resistance to mupirocin, aztreonam, ceftazidime, and/or oxacillin, ampicillin, penicillin, tetracycline, clindamycin, lincomycin, and erythromycin. This study presents the antimicrobial susceptibility profiles of Brazilian
C. diphtheriae isolates. The data are of value to practitioners, and suggest that some concern exists regarding the use of penicillin.
