METRONIDAZOLE SUSCEPTIBILITY AND THE PRESENCE OF HYDROGENASE IN PATHOGENIC BACTERIA

Metronidazole has been shown to be reduced intracellularly by a ferred oxin-linked hydrogenase mediated mechanism in Clostridia, Pathogenic b acterial isolates representative of aerobic, fastidious, facultative, microaerophilic and obligate anaerobic metabolism were therefore surve yed for the presence of hydrogenase activity using a rapid commercial semi-quantitative assay adapted for this purpose. The presence of an a ctive hydrogenase was then correlated to the organism's antimicrobial susceptibility to metronidazole. Most obligate anaerobic organisms tha t had an active hydrogenase were sensitive to metronidazole. Exception s included a well-known metronidazole resistant B. fragilis strain NCT C 11295, two strains of C. bifermentans and single isolates of Veillon ella parvula, Fusobacterium necrophorum, Fusobacterium nucleatum, Euba cterium lentum, and Peptostreptococcus magnus. All Propionibacterium s pp. and Lactobacillus spp, isolates did not have any hydrogenase activ ity and were resistant to metronidazole. Although all Helicobacter pyl ori isolates had hydrogenase activity, five out of ten (50%) isolates were resistant to metronidazole. This study demonstrates that the pres ence of hydrogenase correlates closely but not absolutely across a wid e range of microorganisms with susceptibility to metronidazole. (C) 19 96 Academic Press