Véronique Vernet-Garnier

Rapid detection of qnr and qepA plasmid-mediated quinolone resistance genes using real-time PCR.

Plasmid-mediated quinolone resistance genes in clinical strains cannot be detected by phenotypic traits but require gene detection. We developed a multiplex real-time polymerase chain reaction (PCR) assay using high-resolution melting master mix with ResoLight dye to detect qnr genes and a simplex real-time PCR assay using SYBR Green I to detect qepA genes. Using qnr-positive and qepA1-positive control strains, the ResoLight method was able to rapidly identify qnrA, qnrB, qnrS, qnrC, and qnrD genes; the SYBR Green I method identified qepA genes. Among 118 extended spectrum beta-lactamase-producing Enterobacteriaceae isolates, the 2 new assays efficiently detected and identified qnr in 9 strains, but no qepA gene. To our knowledge, this is the first study describing the detection of all 5 qnr and qepA genes using real-time PCR. The 2 tests constitute a significant step forward for screening for plasmid quinolone resistance genes in clinical strains.

Rapid Detection of aac(6′)-Ib-cr Quinolone Resistance Gene by Pyrosequencing

ABSTRACT Pyrosequencing was used to rapidly detect aac(6′)-Ib and aac(6′)-Ib-cr genes. This plasmid-mediated quinolone resistance determinant is increasing in extended-spectrum beta-lactamase-producing Enterobacteriaceae. This method is faster and more cost-effective than the methods previously described. Sequences obtained with this pyrosequencing method showed 100% concordance with conventional sequencing.

Rapid detection of quinolone resistance gene aac(6')-Ib-cr by pyrosequencing

ABSTRACT Pyrosequencing was used to rapidly detect aac(6′)-Ib and aac(6′)-Ib-cr genes. This plasmid-mediated quinolone resistance determinant is increasing in extended-spectrum beta-lactamase-producing Enterobacteriaceae. This method is faster and more cost-effective than the methods previously described. Sequences obtained with this pyrosequencing method showed 100% concordance with conventional sequencing.

Gastroscopy-associated transmission of extended-spectrum beta-lactamase-producing Pseudomonas aeruginosa

An unusual multi-drug-resistant Pseudomonas aeruginosa (MDR-PA) was isolated in four patients whilst hospitalized in a French teaching hospital between May and August 2011. All four patients had undergone an oesophago-gastro-duodenoscopy with the same gastroscope over a five-month period. This endoscope was associated with a culture positive for the MDR-PA. Observations of endoscope reprocessing identified deviations from the agreed processes: insufficient initial cleaning, shortening of the immersion time and brushing time, insufficient channel flushing, and inadequate drying prior to storage. Since withdrawing the gastroscope and institution of strict adherence to the agreed processes, no other MDR-PA cases have been isolated.

Description of a 2,683-base-pair plasmid containing qnrD in two Providencia rettgeri isolates.

ABSTRACT qnr genes are plasmid-mediated quinolone resistance genes mainly harbored on large conjugative multiresistant plasmids. The qnrD gene was recently observed in Salmonella enterica on a small nonconjugative plasmid (p2007057). We describe two strains of Providencia rettgeri harboring qnrD on nonconjugative plasmids. The plasmids were 99% identical, with 2,683 bp and four open reading frames, including qnrD, but exhibited only 53% identity with the plasmid found in S. enterica.

Mobile Insertion Cassette Elements Found in Small Non-Transmissible Plasmids in Proteeae May Explain qnrD Mobilization

qnrD is a plasmid mediated quinolone resistance gene from unknown origin, recently described in Enterobacteriaceae. It encodes a pentapeptide repeat protein 36–60% different from the other Qnr (A, B, C, S and VC). Since most qnrD-positive strains were described as strains belonging to Proteus or Providencia genera, we hypothesized that qnrD originated in Proteeae before disseminating to other enterobacterial species. We screened 317 strains of Proteeae for qnrD and its genetic support by PCR. For all the seven qnrD-positive strains (4 Proteus mirabilis, 1 Proteus vulgaris and 2 Providencia rettgeri) the gene was carried onto a small non-transmissible plasmid, contrarily to other qnr genes that are usually carried onto large multi-resistant plasmids. Nucleotide sequences of the qnrD-bearing plasmids were 96% identical. Plasmids contained 3 ORFs apart from qnrD and belonged to an undescribed incompatibility group. Only one plasmid, in P. vulgaris, was slightly different with a 1,568-bp insertion between qnrD and its promoter, leading to absence of quinolone resistance. We sought for similar plasmids in 15 reference strains of Proteeae, but which were tested negative for qnrD, and found a 48% identical plasmid (pVERM) in Providencia vermicola. In order to explain how qnrD could have been inserted into such native plasmid, we sought for gene mobilization structures. qnrD was found to be located within a mobile insertion cassette (mic) element which sequences are similar to one mic also found in pVERM. Our conclusions are that (i) the small non-transmissible qnrD-plasmids described here may result from the recombination between an as-yet-unknown progenitor of qnrD and pVERM, (ii) these plasmids are maintained in Proteeae being a qnrD reservoir (iii) the mic element may explain qnrD mobilization from non-transmissible plasmids to mobilizable or conjugative plasmids from other Enterobacteriaceae, (iv) they can recombined with larger multiresistant plasmids conjugated in Proteeae.

Fluoroquinolone Resistance Mechanisms and population structure of Enterobacter cloacae non-susceptible to Ertapenem in North-Eastern France.

Fluoroquinolone (FQ) agents are a potential resort to treat infection due to Enterobacteriaceae producing extended spectrum β-lactamase and susceptible to FQ. In a context of increase of non-susceptibility to carbapenems among Enterobacteriaceae, we characterized FQ resistance mechanisms in 75 Enterobacter cloacae isolates non-susceptible to ertapenem in North-Eastern France in 2012 and describe the population structure by pulsed field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Among them, 14.7% (12/75) carried a carbapenemase-encoding gene. Except one isolate producing VIM-1, the carbapenemase-producing isolates carried the well-known IncL/M pOXA48a plasmid. Most of the isolates (59/75) harbored at least a FQ-R determinant. qnr genes were predominant (40%, 30/75). The MLST study revealed that E. cloacae isolates’ clonality was wide [24 different sequence types (STs)]. The more widespread STs were ST74, ST101, ST110, ST114, and ST133. Carbapenem MICs were higher for E. cloacae ST74 than for other E. cloacae isolates. Plasmid-mediated quinolone resistance determinants were more often observed in E. cloacae ST74 isolates. These findings showed that (i) pOXA-48a is spreading in North-Eastern France, (ii) qnr is preponderant in E. cloacae, (iii) E. cloacae comprised a large amount of lineages spreading in North-Eastern France, and (iv) FQ as an alternative to β-lactams to treat ertapenem non-susceptible Enterobacteriaceae are compromised.

Symptomatic and Asymptomatic Neurological Complications of Infective Endocarditis: Impact on Surgical Management and Prognosis.

Objectives Symptomatic neurological complications (NC) are a major cause of mortality in infective endocarditis (IE) but the impact of asymptomatic complications is unknown. We aimed to assess the impact of asymptomatic NC (AsNC) on the management and prognosis of IE. Methods From the database of cases collected for a population-based study on IE, we selected 283 patients with definite left-sided IE who had undergone at least one neuroimaging procedure (cerebral CT scan and/or MRI) performed as part of initial evaluation. Results Among those 283 patients, 100 had symptomatic neurological complications (SNC) prior to the investigation, 35 had an asymptomatic neurological complications (AsNC), and 148 had a normal cerebral imaging (NoNC). The rate of valve surgery was 43% in the 100 patients with SNC, 77% in the 35 with AsNC, and 54% in the 148 with NoNC (p<0.001). In-hospital mortality was 42% in patients with SNC, 8.6% in patients with AsNC, and 16.9% in patients with NoNC (p<0.001). Among the 135 patients with NC, 95 had an indication for valve surgery (71%), which was performed in 70 of them (mortality 20%) and not performed in 25 (mortality 68%). In a multivariate adjusted analysis of the 135 patients with NC, age, renal failure, septic shock, and IE caused by S. aureus were independently associated with in-hospital and 1-year mortality. In addition SNC was an independent predictor of 1-year mortality. Conclusions The presence of NC was associated with a poorer prognosis when symptomatic. Patients with AsNC had the highest rate of valve surgery and the lowest mortality rate, which suggests a protective role of surgery guided by systematic neuroimaging results.

Mise au point d’une technique de PCR en temps réel pour la détection rapide des gènes qnr chez des entérobactéries productrices de bêta-lactamases à spectre étendu

AIM OF THE STUDY To develop a fast and reliable real time PCR technique for detecting plasmid-mediated quinolone resistance genes qnrA, qnrB and qnrS. METHODS A real-time PCR assay using SYBR Green I and Roche LightCycler(®) was developed to detect qnr genes. Detection of qnr genes was based on comparison of melting temperature differences with a positive control of each qnr genes. This assay was performed to study 138 isolates collected from diagnostic and screening samples in the Champagne-Ardenne region in 2004 (France). RESULTS In optimized conditions, the three positive controls tested alone and with isolates confirmed the specificity of the PCR primers. Each PCR assay was able to test 30 strains in 60min for 1 qnr gene. Out of 138 isolates screened, 3.6 % isolates were positive for a qnrA1, 1.5 % for qnrS1 and no qnrB-like gene. Prevalence of qnr determinants was 5 % and reached 9.5 % in clinical isolates. CONCLUSION Real-time PCR is a fast and reliable technique for screening of qnr-positive strains. This study shows a relatively high prevalence of qnr determinants (5 %) among ESBL-producing Enterobacteriaceae.

Factors associated with carriage of carbapenem-non-susceptible Enterobacteriaceaein North-Eastern France and outcomes of infected patients

Background Carbapenems are frequently used as a last resort to treat infections caused by multidrug-resistant Gram-negative organisms, thus carbapenem-non-susceptible Enterobacteriaceae (CNSE) is an emerging health threat. Objectives To assess risk factors and outcomes of CNSE carriage. Patients and methods We conducted a matched case-control study in six hospitals in North-Eastern France. The controls were patients harbouring carbapenem-susceptible Enterobacteriaceae. Fifty-five cases and 110 controls were included. Results Most of the CNSE isolates were Enterobacter cloacae and Klebsiella pneumoniae . Carbapenemase production was observed in 40% of isolates and they produced OXA-48 only. CNSE carriage was significantly associated with recent antibiotic use ( P =  0.014), particularly carbapenems ( P =  0.03) and fluoroquinolones ( P =  0.016). A multivariate analysis using conditional logistic regression showed that the presence of concomitant infection(s) (OR: 9.83; 95% CI 3.04-21.39, P =  0.0031), nosocomial infections (OR: 7.84; 95% CI 2.00-12.54, P  =   0.0063) and a high age (OR: 1.07; 95% CI 1.01-1.06, P =  0.038) were independently associated with CNSE carriage. Moreover, patients infected with CNSE had worse outcomes: fewer resolved infections at 1 month ( P =  0.02), and they had a higher mortality rate ( P =  0.0004) and longer hospital stays ( P =  0.02). Conclusions We identified three independent risk factors for CNSE carriage as well as worse outcomes in infected patients in North-Eastern France. This highlights the importance of early detection of CNSE and the need for antimicrobial therapy re-evaluation after bacteriological analysis has been performed.