EVALUATION OF ANTIMICROBIAL SUSCEPTIBILITY PATTERNS AND ?-LACTAMASE PRODUCTION BY CLOSTRIDIUM SPECIES ISOLATED FROM FOOD AND FAECAL SPECIMENSIN LAGOS, NIGERIA

E. E. Chukwu; Ogunsola, F.T., Nwaokorie, F.O; A. O. Coker; Llanco, L.A., Avila-Campos, M.J

E. E. Chukwu 1Department of Medical Microbiology and Parasitology, College of Medicine, University of Lagos, Nigeria
Ogunsola, F.T., Nwaokorie, F.O University of Lagos, Nigeria
A. O. Coker 3Department of Medical Microbiology and Parasitology, Babcock University Teaching Hospital, Ilishan, Remo, Ogun state, Nigeria
Llanco, L.A., Avila-Campos, M.J 4Anaerobe Laboratory, Department of Microbiology, Institute of Biomedical Sciences, University of S�o Paulo-USP, Av. LineuPrestes, 2415-242 S�o Paulo, SP, Brazil

Keywords: Anaerobic bacteria, Empirical treatment, Resistance, Antimicrobial susceptibility, Clostridiumperfringens.

Abstract

The susceptibility patterns of anaerobic bacteria have become increasingly unpredictable challenging the concept of reliable anaerobic therapy and empirical treatment. Resistance to even the most active drugs, such as amoxicillin and metronidazole, has been reported. These factors emphasize the need for antimicrobial susceptibility testing of anaerobes as well as periodic surveillance to detect geographic or temporal trends. We evaluated the invitro antimicrobial susceptibility of 56 Clostridium speciesisolated from food commodities and faecal specimens in Lagos State to five antibiotics. Testing was done by agar dilution method on Wilkins-Chalgren agar supplemented with hemin (5 g/ml) and vitamin K (1 g/ml) as recommended by Clinical Laboratory Standard Institute. Bacteria strains resistant to amoxicillin were tested for the Production of ?-lactamase by nitrocefin disk assay method. The antibiotics used were amoxicillin, clindamycin, erythromycin, tetracycline and metronidazole. The strains were more susceptible to metronidazole (96.4%). This was followed by amoxicillin (91.1%)) and tetracycline (80.4%). High level of resistance was observed with clindamycin (33.9%) and erythromycin (28.6%). The MIC range of metronidazole was 0.125-32 g/ml with MIC₅₀ at 1.0 g/ml and MIC₉₀at 8.0 g/ml respectively. The MIC₉₀for tetracycline, erythromycin, clindamycin and amoxicillin are 8.0g/ml, 64 g/ml, 64 g/ml and 0.5 g/ml respectively. This result shows that food products sold in Lagos State may serve as possible vehicles for the transmission of drug-resistant strains of Clostridium species. Metronidazole remains the drug of choice for the treatment of clostridial infections and indeed anaerobic infections. However, the presence of resistant strains should not be overlooked.