We characterized 67 Escherichia coli isolates with reduced susceptibility to cefotaxime obtained from 136 samples of healthy broilers housed in 36 Tunisian farms. All these isolates harboured blaCTX‐M‐1 and/or blaCMY‐2 genes located mostly on self‐conjugative IncI1 plasmids. qnrS1, qnrA6 and aac(6′)‐Ib‐cr were detected in six isolates. Considerable genetic diversity was detected among isolates from different farms. To our knowledge, this is the first detailed documentation of a high occurrence of blaCTX‐M‐1 and blaCMY‐2 in E. coli at the poultry farm level in Tunisia as well as the first description of plasmid‐mediated quinolone resistance in food animals in Tunisia which may contribute to the dissemination of these genes throughout Tunisia.

Aims: 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.Methods and results: Susceptibility of 200 clinical isolates of Enterobacteriaceae to colistin was tested to compare agar dilution (reference method), disc diffusion (50 and 10 mu g) 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 Comite de l'antibiogramme de la Societe Francaise 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.Conclusion: Disc susceptibility testing methods are unreliable on detecting colistin resistance. MIC should be determined to confirm the susceptibility results by disc diffusion.Significance and Impact of the study: We recommend the determination of MIC by Etest for all multidrug-resistant Enterobacteriaceae when colistin is required for the treatment.

Objective. - The aim of this study was to analyze the distribution of bacteria responsible for community-acquired meningitis and the pattern of resistance of common species.Design. - All bacteriologically confirmed cases of community-acquired meningitis were recorded between 1993 and 2001.Results. - Two hundred twenty-four cases of bacterial meningitis were recorded. The most frequent species were Haemophilus influenzae and Streptococcus pneumoniae followed by Neisseria meningitidis with respectively 37.1%, 32.1%, and 10.7% of cases. The yearly distribution of these bacteria did not show any epidemic peak. Enterobacteria and group B Streptococcus were the most frequently identified pathogens in neonatal meningitis. H. influenzae was the predominant microorganism in children between one month and five years of age, (66.4%) followed by S. pneumoniae (23.5%). S. pneumoniae was the predominant bacteria responsible fore more than half of the cases over five years of age. 28.8% of H. influenzae strains produced P-lactamase. 27.2% of S. pneumoniae strains were less susceptible to penicillin. Resistance rates for amoxicillin and cefotaxime were respectively 10.6% and 7.5%. Only one strain of N. meningitidis (4.2%) presented with a decreased susceptibility to penicillin.Conclusions. - In our study, H. influenzae and S. pneumoniae were the main microorganisms responsible for community-acquired meningitis. High resistance rates were found for these bacteria: 28.8% of H. influenzae to ampicillin and 27.2% of S. pneumoniae to penicillin. (c) 2006 Elsevier SAS. Tous droits reserves.

OBJECTIVE:The aim of this study was to analyze the distribution of bacteria responsible for community-acquired meningitis and the pattern of resistance of common species.DESIGN:All bacteriologically confirmed cases of community-acquired meningitis were recorded between 1993 and 2001.RESULTS:Two hundred twenty-four cases of bacterial meningitis were recorded. The most frequent species were Haemophilus influenzae and Streptococcus pneumoniae followed by Neisseria meningitidis with respectively 37.1%, 32.1%, and 10.7% of cases. The yearly distribution of these bacteria did not show any epidemic peak. Enterobacteria and group B Streptococcus were the most frequently identified pathogens in neonatal meningitis. H. influenzae was the predominant microorganism in children between one month and five years of age, (66.4%) followed by S. pneumoniae (23.5%). S. pneumoniae was the predominant bacteria responsible fore more than half of the cases over five years of age. 28.8% of H. influenzae strains produced beta-lactamase. 27.2% of S. pneumoniae strains were less susceptible to penicillin. Resistance rates for amoxicillin and cefotaxime were respectively 10.6% and 7.5%. Only one strain of N. meningitidis (4.2%) presented with a decreased susceptibility to penicillin.CONCLUSIONS:In our study, H. influenzae and S. pneumoniae were the main microorganisms responsible for community-acquired meningitis. High resistance rates were found for these bacteria: 28.8% of H. influenzae to ampicillin and 27.2% of S. pneumoniae to penicillin.