Publications (2)2.34 Total impact
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Article: Epidemiological study of Enterobacteriaceae resistance to colistin in Sfax (Tunisia).
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ABSTRACT: The authors had for aim to monitor Enterobacteriaceae resistance to colistin, during 6 years (2005-2010), and to study the epidemiology of Enterobacteriaceae resistant strains isolated in the Sfax region (Tunisia). This retrospective study was carried out in the microbiology laboratory, at the Habib Bourguiba teaching hospital in Sfax. All strains of colistin resistant Enterobacteriaceae isolated from patients were studied. One hundred and twenty one strains of colistin resistant Enterobacteriaceae were isolated from 93 patients. Klebsiella pneumoniae was the most frequent species (60.2%), followed by Enterobacter cloacae (26.9%), and Escherichia coli (12.9%). Thirteen strains (E. cloacae) were heteroresistant to colistin. Eighty one isolates (87.1%) were resistant to third generation cephalosporins. The rate of resistance to colistin ranged from 0.09% for E. coli to 1.2% for K. pneumoniae, and 1.5% for E. cloacae. A progressively increasing colistin resistance was observed for K. pneumoniae. Most resistant strains were isolated from urine in the urology department. Previous exposure to colistin was reported in 59.2% of patients. Pulsed field gel electrophoresis typing revealed different clones. Colistin resistance in Enterobacteriaceae is a worrying phenomenon in Sfax. It is related to polyclonal diffusion. Continuous epidemiological monitoring and a rational use of colistin are necessary to limit the spreading of these colistin resistant strains and to maintain this antibiotic's effectiveness.Médecine et Maladies Infectieuses 05/2012; 42(6):256-63. · 0.72 Impact Factor -
Article: Comparison of disc diffusion, Etest and agar dilution for susceptibility testing of colistin against Enterobacteriaceae.
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ABSTRACT: In this study, we compared different methods of colistin susceptibility testing, disc diffusion, agar dilution and Etest using a set of Enterobacteriaceae isolates that included colistin-resistant strains. Susceptibility of 200 clinical isolates of Enterobacteriaceae to colistin was tested to compare agar dilution (reference method), disc diffusion (50 and 10 μg) and Etest. MICs (minimum inhibitory concentrations) were interpreted using the criteria established by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Colistin exhibited excellent activity against Escherichia coli and E. cloacae (MIC90 = 0·5 mg l(-1)). In contrast, colistin was less active against Klebsiella pneumoniae (MIC90 = 16 mg l(-1)). Resistance rates varied from 0% in E. coli to 1·8% in E. cloacae and 13% in K. pneumoniae. High rates of very major errors were observed in the disc diffusion test using either the criteria of the Comité de l'antibiogramme de la Société Française de Microbiologie (CA-SFM) or the criteria of the Clinical and Laboratory Standards Institute (CLSI), respectively, 3·5 and 2·5%. When the criteria of Gales et al. were applied, the number of very major errors was reduced to one (0·5%). The Etest showed good concordance with agar dilution method. Disc susceptibility testing methods are unreliable on detecting colistin resistance. MIC should be determined to confirm the susceptibility results by disc diffusion. We recommend the determination of MIC by Etest for all multidrug-resistant Enterobacteriaceae when colistin is required for the treatment.Letters in Applied Microbiology 09/2011; 53(5):546-51. · 1.62 Impact Factor
