Plasmid Profile Analysis and Curing of Multidrug-resistant Bacteria Isolated from Two Hospital Environments in Calabar Metropolis, Nigeria

Abstract

Objective: The objective of this study was to determine the plasmid profile and curing of environmental isolates from General and Infectious Disease hospitals showing multi-drug resistance. Methods: Isolates were obtained from air and surfaces of two hospitals using standard microbiological techniques. The isolates were then subjected to sensitivity using ofloxacin, reflacine, ciprofloxacin, augmentin, gentamycin, streptomycin, ceporex, nalidixic acid, septrin, amplicin, norfloxacin, amoxyl, erythromycin, chloramphenicol, ampiclox, levofloxacin, ampicillin, cefoxitin, amoxicillin and ceftazidime. Multi-drug resistant isolates were then selected for plasmid DNA analysis, quantification, electrophoresis and curing. Results: The isolates that showed resistance to more than two antibiotics were S. aureus,             E. aerogenes, C. freundii, K. pneumoniae, P. aeruginosa, Salmonella species, S. marcescens, Proteus species, S. marcescens, E. coli, and coagulase-negative Staphylococcus. The extracted plasmid DNA ranged from 1.2 - 80.5 ng/ml in quantity and showed the presence of SHV, CTX-M and MecA genes in the isolates with sizes of 154, 300 and 600-1000 bp, respectively. All isolates had SHV while a few had CTX-M genes except S. aureus and coagulase-negative S. aureus which had mecA gene in addition. Chi-square and Fisher exact test for SHV gene was significant while CTX-M was not. Treatment with ethidium bromide showed that at a concentration of 0-20 µl, all isolates exhibited very heavy growth (+++), at 50-100 µl, only P. aeruginosa showed very heavy growth (+++) while other organisms showed heavy to moderate growth. However, at 400 to 1,000 µl, no growth was observed. Conclusion: The presence of plasmid-borne multiple resistant genes is of great public health concern and this highlights the need for antibiogram and molecular typing in the control of nosocomial infections.