Julien Bador

Epidemiology and resistance of Achromobacter xylosoxidans from cystic fibrosis patients in Dijon, Burgundy: First French data

BACKGROUND Achromobacter xylosoxidans is an emerging pathogen in cystic fibrosis (CF) patients recognised as causal agent of inflammation. The prevalence of infection or colonisation is variable among CF centres. We report here the first epidemiological data about A. xylosoxidans in a French CF centre: Dijon, Burgundy. METHODS All isolates recovered from the patients affiliated with our centre in 2010 since their first visit were included. Antimicrobial susceptibility was determined by disk diffusion method and E-test. Molecular epidemiology was performed by Pulsed Field Gel Electrophoresis (PFGE) and compared with repetitive sequence-based PCR (rep-PCR, DiversiLab®). We also sequenced the constitutive bla-oxa-114 gene. RESULTS Out of 120 patients, 21 (17.5%) had at least one positive culture with A. xylosoxidans since they started to receive routine care in our CF centre (447 isolates). Median age at first positive culture was 16 years (range 3-34 years). Most patients were colonised by their own strain, cross-contamination was very rare. We observed two cases of intra-family spread. DiversiLab® is a useful tool as efficient as PFGE to compare isolates recovered simultaneously from different patients when an outbreak is suspected. However, PFGE remains the reference method for long-term survey of chronically colonised patients. We detected new OXA-114 variants and the new oxacillinase OXA-243 (88% amino acid identity with OXA-114). Acquired resistance to ciprofloxacin, ceftazidime and carbapenems was frequent. In 2010, 7 patients harboured strains resistant to ceftazidime, 6 patients strains with decreased susceptibility to carbapenems (especially meropenem) and 12 patients strains resistant to ciprofloxacin. CONCLUSIONS In our centre, the high prevalence of colonisation is not due to cross-contamination. Our main concern is the high rate of antimicrobial resistance.

First Description of an RND-Type Multidrug Efflux Pump in Achromobacter xylosoxidans, AxyABM

ABSTRACT 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 resistance-nodulation-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.

Innate Aminoglycoside Resistance of Achromobacter xylosoxidans Is Due to AxyXY-OprZ, an RND-Type Multidrug Efflux Pump

ABSTRACT 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.

Distribution of innate efflux-mediated aminoglycoside resistance among different Achromobacter species

Achromobacter spp. are emerging respiratory pathogens in cystic fibrosis patients. Since 2013 the genus Achromobacter includes 15 species for which innate antibiotic resistance is unknown. Previously the AxyXY-OprZ efflux system has been described to confer aminoglycoside (AG) resistance in A. xylosoxidans. Nevertheless, some Achromobacter spp. strains are susceptible to AG. This study including 49 Achromobacter isolates reveals that AG resistance is correlated with different Achromobacter spp. It is noteworthy that the axyXY-oprZ operon is detected only in AG-resistant species, including the most frequently encountered in cystic fibrosis patients: A. xylosoxidans, A. ruhlandii, A. dolens and A. insuavis.

Distribution of the species of Achromobacter in a French Cystic Fibrosis Centre and multilocus sequence typing analysis reveal the predominance of A. xylosoxidans and clonal relationships between some clinical and environmental isolates

BACKGROUND Achromobacter spp. are emerging pathogens in Cystic Fibrosis (CF) patients. Recent studies proposed Multilocus Sequence Typing (MLST) scheme and a species-level identification method by nrdA sequencing for this genus. Epidemiological data are needed to assess the species and/or the sequence types (STs) involved and their potential role in CF patients lung function degradation. The aims of this study were i) to describe the distribution of the different species of Achromobacter in our CF centre ii) to detect potential STs more involved in chronic colonisations iii) to detect a potential local or worldwide predominance of some STs among clinical and environmental isolates. METHODS All the isolates (477) collected in our CF centre from 2007 to 2014 among the 177 patients attending the centre were identified using nrdA sequencing. MLST analysis was performed for 37 clinical and 14 environmental isolates. RESULTS A total of 47 out of 177 patients presented positive culture(s) with Achromobacter spp., representing 12.7% of the patients of the centre each year. Eleven species were detected, A. xylosoxidans being the most prevalent species (27 patients). Only A. xylosoxidans (>80%) and A. insuavis were involved in chronic colonisation (6.7%). MLST analysis revealed a wide diversity among the isolates (36 STs for 51 isolates). Nevertheless, one third of the isolates belonged to STs previously detected in clinical isolates from other countries. CONCLUSIONS This study is a first approach in understanding the global epidemiology of Achromobacter species in CF. These results confirm the high prevalence of the species A. xylosoxidans among CF patients, reveal the worldwide distribution of some STs and point out the potential role of environmental sources of contamination. More studies are needed to search for relationships between species and/or ST and pathogenicity.

Outbreak of Extended-Spectrum Beta-Lactamase Producing Enterobacter cloacae with High MICs of Quaternary Ammonium Compounds in a Hematology Ward Associated with Contaminated Sinks

Objective: To investigate an outbreak of extended-spectrum beta-lactamase (ESBL) producing Enterobacter cloacae that occurred in the Hematology ward (24-bed unit) of the François Mitterrand University Hospital (Dijon, France) between January 2011 and December 2013. The outbreak involved 43 patients (10 infected and 33 colonized). Design: We performed environmental analysis to detect multiresistant E. cloacae for comparison with clinical isolates (genotyping by pulsed-field gel electrophoresis and MLST as well as ESBL-typing) and determined the MICs of the quaternary ammonium compounds (QACs) alkyldimethylbenzylammonium chloride (ADBAC) and didecyldimethylammonium chloride (DDAC). A bleach-based cleaning-disinfection program was implemented in December 2012 after mechanical removal of the biofilm in all sinks. Results: We have detected 17 ESBL-producing E. cloacae in patients sink drains, shower drains and medical sink drains. Sequencing of the bla genes performed on 60 strains recovered from patients and environment (n = 43 clinical and n = 17 environmental) revealed that bla CTX−M15 was predominant (37 isolates) followed by bla CTX−M9 plus bla SHV−12 (20 isolates). We observed a great diversity among the isolates: 14 pulsotypes (11 STs) in clinical isolates and 9 pulsotypes (7 STs) in environmental isolates. Six pulsotypes were identical between clinical and environmental isolates. MICs of the quaternary ammonium compounds widely used for disinfection were very high in clinical and environmental isolates. Immediately after the implementation of the disinfection program we noticed a substantial fall in cases number. Our findings demonstrate the role of drains as important reservoir of ESBL-producing E. cloacae and highlight the necessity to settle drains accessible to achieve correct cleaning as well as to use disinfectant with proved activity against nosocomial pathogens.

Nosocomial Infections with IMP-19−Producing Pseudomonas aeruginosa Linked to Contaminated Sinks, France

We isolated IMP-19–producing Pseudomonas aeruginosa from 7 patients with nosocomial infections linked to contaminated sinks in France. We showed that blaIMP-19 was located on various class 1 integrons among 8 species of gram-negative bacilli detected in sinks: P. aeruginosa, Achromobacter xylosoxidans, A. aegrifaciens, P. putida, Stenotrophomonas maltophilia, P. mendocina, Comamonas testosteroni, and Sphingomonas sp.

Streptococcus pyogenes : an unusual cause of salpingitis. Case report and review of the literature

BackgroundStreptococcus pyogenes can colonize genitourinary tract, but it is a rare cause of salpingitis.Case reportWe report a case of bilateral salpingitis due to Streptococcus pyogenes in a 34-year-old woman using an intra-uterine device and which occurred following a family history of recurrent S. pyogenes infections. We review 12 other cases reported in the literature, and discuss the pathophysiological mechanisms of this potentially life-threatening disease.ConclusionIt is important to take into account consider Streptococcus pyogenes as a cause of acute salpingitis in the context of recent intra-familial Streptococcus pyogenes infections.

Role of AxyZ Transcriptional Regulator in Overproduction of AxyXY-OprZ Multidrug Efflux System in Achromobacter Species Mutants Selected by Tobramycin

ABSTRACT AxyXY-OprZ is an RND-type efflux system that confers innate aminoglycoside resistance to Achromobacter spp. We investigated here a putative TetR family transcriptional regulator encoded by the axyZ gene located upstream of axyXY-oprZ. An in-frame axyZ gene deletion assay led to increased MICs of antibiotic substrates of the efflux system, including aminoglycosides, cefepime, fluoroquinolones, tetracyclines, and erythromycin, indicating that the product of axyZ negatively regulates expression of axyXY-oprZ. Moreover, we identified an amino acid substitution at position 29 of AxyZ (V29G) in a clinical Achromobacter strain that occurred during the course of chronic respiratory tract colonization in a cystic fibrosis (CF) patient. This substitution, also detected in three other strains exposed in vitro to tobramycin, led to an increase in the axyY transcription level (5- to 17-fold) together with an increase in antibiotic resistance level. This overproduction of AxyXY-OprZ is the first description of antibiotic resistance acquisition due to modification of a chromosomally encoded mechanism in Achromobacter and might have an impact on the management of infected CF patients. Indeed, tobramycin is widely used for aerosol therapy within this population, and we have demonstrated that it easily selects mutants with increased MICs of not only aminoglycosides but also fluoroquinolones, cefepime, and tetracyclines.

Two new Salmonella genomic islands 1 from Proteus mirabilis and description of blaCTX-M-15 on a variant (SGI1-K7)

Objectives To characterize the structure of Salmonella genomic islands 1 (SGI1s) from two clinical Proteus mirabilis isolates: one producing an ESBL and the other a penicillinase. Methods WGS completed by PCR and Sanger sequencing was performed to determine sequences of SGI1s from Pm2CHAMA and Pm37THOMI strains. Results Two new variants of SGI1 named SGI1-Pm2CHAMA (53.6 kb) and SGI1-K7 (55.1 kb) were identified. The backbone of SGI1-Pm2CHAMA shared 99.9% identity with that of SGI1. Its MDR region (26.3 kb) harboured two class 1 integrons (an In2-type integron and an In4-type integron) containing in particular a qacH cassette (encoding a quaternary ammonium compound efflux pump). These two integrons framed a complex region (harbouring among others blaCARB-4) resulting from transposon insertions mediated by IS26 and successive transposition events of ISs (ISAba14 isoform and the new ISPmi2). The second variant (SGI1-K7) had the same backbone as SGI1-K. Its MDR region (29.7 kb) was derived from that of SGI1-K and was generated by three events. The two main events were mediated by IS26: inversion of a large portion of the MDR region of SGI1-K and insertion of a structure previously reported on plasmids carried by prevalent and successful MDR clones of Enterobacteriaceae. This last event led to the insertion of the blaCTX-M-15 gene into SGI1-K7. Conclusions This study confirmed the great plasticity of the MDR region of SGI1 and its potential key role for the dissemination of clinically significant antibiotic resistance among Enterobacteriaceae.