In our centre, the high prevalence of colonisation is not due to cross-contamination. Our main concern is the high rate of antimicrobial resistance.

Achromobacter xylosoxidans is an emerging pathogen in cystic fibrosis patients. The multidrug resistance of these bacteria remains poorly understood. We have characterized in a clinical strain the first resistancenodulation-cell division (RND)-type multidrug efflux pump in this species: AxyABM. The inactivation of the transporter component axyB gene led to decreased MICs of cephalosporins (except cefepime), aztreonam, nalidixic acid, fluoroquinolones, and chloramphenicol.

Objectives: Salmonella genomic island 1 (SGI1) is often encountered in antibiotic-resistant Salmonella enterica and exceptionally in Proteus mirabilis. We investigated the prevalence of SGI1-producing clinical isolates of P. mirabilis in our hospital (Dijon, France).Methods: A total of 57 strains of P. mirabilis resistant to amoxicillin and/or gentamicin and/or trimethoprim/ sulfamethoxazole isolated from August 2011 to February 2012 as well as 9 extended-spectrum b-lactamase (ESBL)-producing P. mirabilis from our collection were tested for the presence of SGI1 by PCR. The complete SGI1 structure from positive isolates [backbone and multidrug resistance (MDR) region] was sequenced.Results: SGI1 was detected in 7 isolates; 5 out of the 57 isolates collected during the study period (9%) and 2 out of the 9 ESBL-producing strains of our collection. The structures of the seven SGI1s were distinct. Three different backbones were identified: one identical to the SGI1 backbone from the epidemic Salmonella Typhimurium DT104, one with variations already described in SGI1-K from Salmonella Kentucky (deletion and insertion of IS1359 in the region spanning from S005 to S009) and one with a variation never detected before (deletion from S005 to S009). Six different MDR regions were identified: four simple variants containing resistance genes already described and two variants harbouring a very complex structure including regions derived from several transposons and IS26 elements with aphA1a never reported to date in SGI1.Conclusions: SGI1 variants are widely distributed among P. mirabilis clinical strains and might spread to other commensal Enterobacteriaceae. This would become a serious public health problem.

No abstract

Two strains of Proteus mirabilis, IpR1 and IpR2, resistant to both imipenem and mecillinam, but susceptible to other beta-lactams were isolated from blood cultures of patients who had been treated with imipenem. Strain IpR1 was isolated in the same sample as a P. mirabilis IpS1 which was susceptible to imipenem and mecillinam. Strains IpR1 and IpR2 did not produce a beta-lactamase and their outer membrane protein profiles were similar to those of IpS1 and P. mirabilis ATCC 29906. Electrophoretic profiles of penicillin-binding proteins (PBPs) showed a decrease in PBP 1A of strains IpR1 and IpR2 compared with IpS1 and ATCC 29906. Competition experiments revealed a decrease in affinity of PBP 2 for imipenem from strain IpR1. These findings suggest that imipenem resistance in P. mirabilis might result from altered PBPs, as reported for Acinetobacter baumanii and Pseudomonas aeruginosa.

This study reports for the first time, to our knowledge, SGI1-positive and PGI1-positive P. mirabilis strains from dogs in France. The genetic diversity of the strains suggests several independent horizontal acquisitions of these MDR elements. The potential transmission of SGI1/PGI1-positive P. mirabilis strains between animals and humans is of public health concern, notably with regard to the spread of ESBL and carbapenemase genes, i.e. bla VEB-6 and bla NDM-1.

PGI1 is a new resistance genomic island from P. mirabilis belonging to the same island family as SGI1. The role of PGI1 in the spread of antimicrobial resistance genes among Enterobacteriaceae of medical importance needs to be evaluated.

TEM-89 (CMT-3) is the first complex mutant ␤-lactamase produced by a clinical strain of Proteus mirabilis (strain Pm 631). This new enzyme, which has a pI of 6.28, is derived from TEM-3 and has a single amino acid substitution also encountered in TEM-59 (inhibitor-resistant TEM ␤-lactamase IRT-17): Ser-130 to Gly. TEM-89 hydrolyzed penicillins to the same extent that TEM-3 did but lost almost all hydrolytic activity for cephalosporins and, like TEM-59, was highly resistant to inhibitors.