A study on Nim expression in Bacteroides fragilis.
Members of the genus Bacteroides, mainly Bacteroides fragilis, can cause severe disease in man, especially after intestinal perforation in the course of abdominal surgery. Treatment is based on a small number of antibiotics, including metronidazole, which has proved to be highly reliable throughout the last 40 to 50 years. Nevertheless, metronidazole resistance does occur in Bacteroides and has been mainly attributed to Nim proteins, a class of proteins with a suggested nitroreductase function. Despite the potentially high importance of Nim proteins for human health, information on the expression of nim genes in B. fragilis is still lacking. It was the aim of this study to demonstrate expression of nim genes in B. fragilis at the protein level and, furthermore, to correlate Nim levels with the magnitude of metronidazole resistance. By the application of 2D gel electrophoresis, Nim proteins could be readily identified in nim-positive strains, but their levels were not elevated to a relevant extent after induction of resistance with high doses of metronidazole. Thus, the data herein do not provide evidence for Nim proteins acting as nitroreductases using metronidazole as a substrate, because no correlation between Nim levels and levels of metronidazole resistance could be observed. Furthermore, no evidence was found that Nim proteins protect B. fragilis from metronidazole by sequestering the activated antibiotic.
Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
David
D
Leitsch
Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, Szeged, Hungary.
József
J
Sóki
Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
Daniel
D
Kolarich
Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, Szeged, Hungary.
Edit
E
Urbán
Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, Szeged, Hungary.
Elisabeth
E
Nagy
D001441:Bacteroides fragilis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008795:Metronidazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D040901:Proteomics / Q000379:methods
D008795:Metronidazole