Multiple drug-resistant Corynebacteriaceae: in vitro and in vivo (murine) studies

Five multiple-drug-resistant (MDR) Corynebacterium isolates, which differed in several biochemical traits, were sensitive to rifampin, vancomycin and ciprofloxacin; ciprofloxacin was more active than enoxacin and norfloxacin. The MDR Corynebacterium isolates uniformly were resistant against fresh human serum, but varied in susceptibility to fresh, defibrinated human blood. In combined blood plus antimicrobial drug assays, vancomycin was more active than rifampin, which in turn was more active than ciprofloxacin. Outbred NMRI mice essentially were resistant against the MDR Corynebacterium isolates, as were mice pretreated with cyclophosphamide (leukopenia), type II Carrageenan (blockade of macrophages), or zymosan (depletion of complement), or with the combination of cyclophosphamide plus zymosan. However, mice pretreated with cyclophosphamide plus type II Carrageenan proved somewhat more susceptible.