Four-year epidemiological study of extended-spectrum beta-lactamase-producing Enterobacteriaceae in a French teaching hospital

International audienceSince the end of the last century resistance to oxyimino -lactams has steadily increased in Enterobacteriaceae. In the present work we studied extended-spectrum -lactamase (ESBL)-producing Enterobacteriaceae strains isolated in the teaching hospital of Clermont-Ferrand, France, between 2006 and 2009. A total of 1368 ESBL-producing isolates were collected. Most of these isolates (69%) were CTX-M-producing Escherichia coli. During the study, the clinical incidence increased by more than 400%, even in the emergency department, and especially in community-acquired infections, as is the case elsewhere in the world. Most of the ESBL-producing isolates remained susceptible to furans and fosfomycin, but only 50% to fluoroquinolons. In conclusion, ESBL-producing bacteria constantly increased during the study period. Unlike many studies, this increase was associated with the wide dissemination of three different CTX-M enzymes: CTX-M-14, CTX-M-15 and CTX-M-1

The MAST® D68C test: an interesting tool for detecting extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae

International audienceThe MastA (R) D68C test is a phenotypical test that allows the detection of extended-spectrum beta-lactamase (ESBL) production, even in AmpC-producing Enterobacteriaceae. We assessed its detection accuracy against a large collection of 106 Enterobacteriaceae isolates producing a wide diversity of well-characterized beta-lactamases (53 ESBL producers, 25 Amp. producers, seven AmpC and ESBL producers, five carbapenemase producers, three carbapenemase and ESBL producers, one AmpC, carbapenemase, and ESBL producer, three TEM-1 producers, three SHV-1 producers, three OXA-1 producers, and one hyperOXY producer, ATCC 35218, ATCC 25922 [a beta-lactamase-negative control strain]). The results were compared with those of the double disk test and the Clinical and Laboratory Standards Institute (CLSI) confirmatory test for the detection of ESBL. The sensitivity was 90.6 % for the synergy test, 87.5 % for the CLSI method, and only 73.1 % for D68C, which, however, reached 92.1 % if the strains for which supplementary investigations were recommended and the complex mutant TEM (CMT)-producing strains were excluded versus 94.1 % and 88.2 % for the other methods. The specificity was 90.2 % for the synergy test and 100 % for the CLSI method and D68C. D68C was also efficient in detecting AmpC-overproducing strains (sensitivity = 97 %, specificity = 95.9 %): among the 74 strains belonging to natural AmpC-producing species, the sensitivity and specificity were 100 and 94.8 %, respectively. The MastA (R) D68C-test is a promising method that is easy to perform for the detection of current ESBLs and could also be useful for the detection of plasmid-encoded AmpC enzymes (sensitivity = 100 %)

Accuracy of a rapid intrapartum group B Streptococcus test: A new immunochromatographic assay

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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

Analysis of Structure-Function Relationships in the Colibactin-Maturating Enzyme ClbP.

pks genomic island of Escherichia coli is involved in the synthesis of the non-ribosomal peptide-type genotoxin colibactin, which has been suggesting as affecting the host immune response and having an impact on cancer development. The pks-encoded enzyme ClbP is an atypical peptidase that contributes to the synthesis of colibactin. In this work, we identified key features of ClbP. Bacterial fractionation and Western-blot analysis revealed the docking of ClbP to the bacterial inner membrane via a C-terminal domain harboring three predicted transmembrane helices. Whereas only one helix was necessary for the location in the inner membrane, the complete sequence of the C-terminal domain was necessary for ClbP bioactivity. In addition, the N-terminal sequence of ClbP allowed the SRP/Sec/YidC- and MreB-dependent translocation of the enzymatic domain in the periplasmic compartment, a feature also essential for ClbP bioactivity. Finally, the comparison of ClbP structure with that of the paralogs FmtA-like and AmpC revealed at an extremity of the catalytic groove a negative electrostatic potential surface characteristic of ClbP. Site-directed mutagenesis experiments identified in this zone two aspartic residues that were important for ClbP bioactivity. Overall, these results suggest a model for precolibactin activation by ClbP and pave a way for the design of inhibitors targeting colibactin production

Three cases of cutaneous mucormycosis with Lichtheimia spp. (ex Absidia/Mycocladus) in ICU. Possible cross-transmission in an intensive care unit between 2 cases

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