Molecular characterization and antimicrobial susceptibilities of extra-intestinal Clostridium difficile isolates

Amongst 25 extra-intestinal clinical isolates of Clostridium difficile, A(+)B(+) (72%) and A(-)B(+) (4%) toxigenic phenotypes, as well as the non-toxigenic phenotype (A(-)B(-)) (24%), were identified. The A(-)B(-) isolates did not express toxin, yet carried part of the tcdA and tcdB gene and are of a previously unreported toxinotype. Six A(+)B(+) isolates also carried binary toxin genes. Resistance to erythromycin (20%), clindamycin (48%), tetracycline (16%), moxifloxacin (16%) and imipenem (11%) occurred but with no apparent correlation to phenotype. None of the strains was resistant to vancomycin or metronidazole. Imipenem-resistance decreased by EDTA, but susceptibility to meropenem suggests the presence of an imipenem specific metalloenzyme.