Achromobacter xylosoxidans is an innately multidrug-resistant pathogen which is emerging in cystic fibrosis (CF) patients. We characterized a new resistance-nodulation-cell division (RND)-type multidrug efflux pump, AxyXY-OprZ. This system is responsible for the intrinsic high-level resistance of A. xylosoxidans to aminoglycosides (tobramycin, amikacin, and gentamicin). Furthermore, it can extrude cefepime, carbapenems, some fluoroquinolones, tetracyclines, and erythromycin. Some of the AxyXY-OprZ substrates are major components widely used to treat pulmonary infections in CF patients.

CTX-M [a major type of extended-spectrum beta-lactamase (ESBL)] producing Escherichia coli are increasingly involved in human infections worldwide. The aim of this study was to investigate potential reservoirs for such strains: soils, cattle, and farm environment. The prevalence of blaCTX-M genes was determined directly from soil DNA extracts obtained from 120 sites in Burgundy (France) using real-time PCR. blaCTX-M targets were found in 20% of the DNA extracts tested. Samples of cattle feces (n = 271) were collected from 182 farms in Burgundy. Thirteen ESBL-producing isolates were obtained from 12 farms and further characterized for the presence of bla genes. Of the 13 strains, five and eight strains carried blaTEM-71 genes and blaCTX-M-1 genes respectively. Ten strains of CTX-M-1 producing E. coli were isolated from cultivated and pasture soils as well as from composted manure within two of these farms. The genotypic analysis revealed that environmental and animal strains were clonally related. Our study confirms the occurrence of CTX-M producing E. coli in cattle and reports for the first time the occurrence of such strains in cultivated soils. The environmental competence of such strains has to be determined and might explain their long term survival since CTX-M isolates were recovered from a soil that was last amended with manure 1 year before sampling.

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 aerobic nonfermentative Gram-negative rod considered an important emerging pathogen among cystic fibrosis (CF) patients worldwide and among immunocompromised patients. This increased prevalence remains unexplained, and to date no environmental reservoir has been identified. The aim of this study was to identify potential reservoirs of A. xylosoxidans in hospital, domestic, and outdoor environments and to compare the isolates with clinical ones. From 2011 to 2012, 339 samples were collected in Dijon's university hospital, in healthy volunteers' homes in the Dijon area, and in the outdoor environment in Burgundy (soil, water, mud, and plants). We designed a protocol to detect A. xylosoxidans in environmental samples based on a selective medium: MCXVAA (MacConkey agar supplemented with xylose, vancomycin, aztreonam, and amphotericin B). Susceptibility testing, genotypic analysis by pulsed-field gel electrophoresis, and bla OXA-114 sequencing were performed on the isolates. A total of 50 strains of A. xylosoxidans were detected in hospital (33 isolates), domestic (9 isolates), and outdoor (8 isolates) samples, mainly in hand washing sinks, showers, and water. Most of them were resistant to ciprofloxacin (49 strains). Genotypic analysis and bla OXA-114 sequencing revealed a wide diversity among the isolates, with 35 pulsotypes and 18 variants of oxacillinases. Interestingly, 10 isolates from hospital environment were clonally related to clinical isolates previously recovered from hospitalized patients, and one domestic isolate was identical to one recovered from a CF patient. These results indicate that A. xylosoxidans is commonly distributed in various environments and therefore that CF patients or immunocompromised patients are surrounded by these reservoirs.

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.