Carbapenemase and virulence factors of Enterobacteriaceae in North Lebanon between 2008 and 2012: evolution via endemic spread of OXA-48

International audienceObjectives: To investigate the resistance to carbapenems in Enterobacteriaceae and the underlying resistance mechanisms in North Lebanon between 2008 and 2012. Methods: A total of 2767 Enterobacteriaceae isolates recovered from clinical samples collected in Nini Hospital ( North Lebanon) were screened for a decrease in susceptibility or resistance to ertapenem ( MIC.0.25 mg/ L). Enterobacteriaceae were similarly screened from 183 faecal samples obtained from non-hospitalized patients. The bacterial isolates were assigned to clonal lineages by PFGE and multilocus sequence typing. Carbapenemase genes, their genetic environment and virulence genes were characterized by molecular approaches. Results: The rate of Enterobacteriaceae exhibiting a decrease in susceptibility or resistance to ertapenem increased from 0.4% in 2008-10 to 1.6% in 2012 for the clinical isolates recovered from hospitalized patients. Of these isolates, scattered among seven enterobacterial species, 88% produced OXA-48 carbapenemase. However, Escherichia coli represented 73% of the OXA-48-producing Enterobacteriaceae collected in 2012 at this hospital. During the faecal carriage study performed in non-hospitalized patients, E. coli was the only species producing OXA-48. The bla(OXA-48) gene was mainly found within Tn1999.2-type transposons inserted into E. coli chromosomes or in similar to 50, similar to 62 or similar to 85 kb plasmids. The plasmids and chromosomal insertswere related to pOXA-48a. Molecular typing of the isolates revealed clonal diversity of E. coli and Klebsiella pneumoniae producing OXA-48. OXA-48 was observed in all major E. coli phylogroups, including D and B2, and isolates harbouring virulence genes of extra-intestinal pathogenic E. coli. Although not belonging to highly virulent capsular genotypes, the OXA-48-producing K. pneumoniae harboured genes associated with virulence or host colonization. Horizontal transfer of related plasmids has facilitated the spread of the blaOXA-48 gene into several Enterobacteriaceae species, including virulent E. coli. Their clonal diversity and the presence of faecal carriers in the community suggest an endemic spread of OXA-48

Significantly Improved Optical OFDM Transmission Performances with 10dB Reduced Optical Input Powers by Quantum Dot SOA Intensity Modulators

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Evaluation of hirst-type sampler and PM10 impactor for investigating adhesion of atmospheric particles onto allergenic pollen grains

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IS1R-Mediated Plasticity of IncL/M Plasmids Leads to the Insertion of bla(OXA-48) into the Escherichia coli Chromosome

International audienceThe OXA-48 carbapenemase is mainly encoded by similar to 62-kb IncL/ M plasmids. However, chromosome-mediated genes have been observed in Escherichia coli isolates. In this work, we investigated the genetic environment of OXA-48 in members of the family Enterobacteriaceae (n = 22) to understand how the OXA-48-encoding gene is transferred into the E. coli chromosome. The OXA-48-encoding gene was located within intact Tn1999.2 transposons in the similar to 62-kb plasmids or within a truncated variant of Tn1999.2 for the OXA-48-encoding genes located in the chromosomes of E. coli bacteria. The analysis of the Tn1999.2 genetic environment revealed an inverted orientation of the transposon in five similar to 62-kb plasmids (5/ 14 [35%]) and in all chromosome inserts (n = 8). The sequencing of pRA35 plasmid showed that this orientation of Tn1999.2 and the acquisition of an IS1R insertion sequence generated a 21.9-kb IS1R-based composite transposon encoding OXA-48 and designated Tn6237. The sequencing of a chromosomal insert encoding OXA-48 also revealed this new transposon in the E. coli chromosome. PCR mapping showed the presence of this element in all strains harboring an OXA-48-encoding chromosomal insert. However, different insertion sites of this transposon were observed in the E. coli chromosome. Overall, these findings indicate a plasticity of the OXA-48 genetic environment mediated by IS1R insertion sequences. The insertion sequences can induce the transfer of the OXA-encoding gene into E. coli chromosomes and thereby promote its persistence and expression at low levels

The epidemiology of Candida species in the Middle East and North Africa

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