Clonal dissemination of vancomycin-resistant Enterococcus faecium ST412 in a Brazilian region

ABSTRACT Vancomycin-resistant Enterococcus faecium (VREfm) has emerged as an important global nosocomial pathogen, and this trend is associated with the spread of high-risk clones. Here, we determined the genetic and phenotypic features of 93 VREfm isolates that were obtained from patients in 13 hospitals in Vitória, Espírito Santo, Brazil, during 2012-2013. All the isolates were vancomycin-resistant and harbored the vanA gene. Only 6 (6.5%) of the VREfm isolates showed the ability to form biofilm. The 93 isolates analyzed belong to a single pulsed-field gel electrophoresis lineage and presented six subtypes. MLST genotyping showed that all VREfm belonged to ST412 (the high-risk clone, hospital-adapted). The present study describes the dissemination of ST412 clone in the local hospitals. The clonal spread of these ST412 isolates in the area we analyzed as well as other hospitals in southeastern Brazil supports the importance of identifying and controlling the presence of these microorganisms in health care-related services.

Colonización por enterococo resistente a vancomicina en pacientes internados en un hospital de Lima, Perú / Colonization by Enterococcal Strains Resistant to Vancomycin in Patients from a Hospital in Lima, Peru

RESUMEN Con el objetivo de determinar la frecuencia de colonización por el enterococo resistente a vancomicina (ERV), el genotipo de resistencia y los factores asociados, se realizó un estudio de tipo transversal durante noviembre y diciembre del 2013 en el Hospital Nacional Cayetano Heredia en Lima, Perú. Se encontró una frecuencia de colonización por ERV de 6,2% (IC 95%: 1,67-10,73), todas las cepas aisladas tenían el genotipo de resistencia vanA, y se halló que las variables hospitalización previa (p=0,001) y el uso de cefalosporinas de tercera generación (p=0,016) estaban asociadas a la colonización por ERV. En conclusión, existe colonización perianal por ERV en los diversos servicios de hospitalización, el gen vanA podría ser transmitido a gérmenes más virulentos y ocasionar la aparición de la bacteria Staphylococcus aureus resistente a vancomicina (VRSA). Es necesario adoptar medidas de control de infecciones para evitar la transmisión de esta bacteria en el ambiente hospitalario.

ABSTRACT This cross-sectional study was conducted from November to December of 2013 at the Cayetano Heredia National Hospital in Lima, Peru, to determine the rate of infection with vancomycin-resistant enterococcus (VRE), the resistance genotype, and associated factors. The rate of infection with VRE was 6.2% (95% confidence interval [CI]: 1.67-10.73) and the resistance genotype isolated from all strains was the vanA gene. The factors associated with colonization with VRE were previous hospitalizations (p = 0.001) and the use of third-generation cephalosporins (p = 0.016). In conclusion, perianal colonization with VRE is present in many hospital services. Moreover, the vanA gene may cause resistance to vancomycin and promote the development of vancomycin-resistant Staphylococcus aureus. Therefore, infection control measures should be adopted to prevent the dissemination of this bacterial strain in hospital settings.

Detection of vancomycin-resistant enterococci (VRE) in stool specimens submitted for Clostridium difficile toxin testing

Abstract The aim of this study was to determine the association between Clostridium difficile (C. difficile) and vancomycin-resistant Enterococcus (VRE) and efficacy of screening stools submitted for C. difficile toxin assay for prevalence of VRE. Between April 2012 and February 2014, 158 stool samples submitted for C. difficile toxin to the Marmara University Microbiology Laboratory, were included in the study. Stool samples were analyzed by enzyme immuno assay test; VIDAS (bioMerieux, France) for Toxin A&B. Samples were inoculated on chromID VRE (bioMerieux, France) and incubated 24 h at 37 °C. Manuel tests and API20 STREP (bioMerieux, France) test were used to identify the Enterococci species. After the species identification, vancomycin and teicoplanin MIC's were performed by E test and molecular resistance genes for vanA vs vanB were detected by polymerase chain reaction (PCR). Of the 158 stool samples, 88 were toxin positive. The prevalence of VRE was 17%(n:19) in toxin positives however, 11.4% in toxin negatives(n:70). All VRE isolates were identified as Enterococcus faecium. These results were evaluated according to Fischer's exact chi-square test and p value between VRE colonization and C. difficile toxin positivity was detected 0.047 (p < 0.05). PPV and NPV were 79% and 47% respectively. In our study, the presence of VRE in C. difficile toxin positives is statistically significant compared with toxin negatives (p < 0.05). Screening for VRE is both additional cost and work load for the laboratories. Therefore VRE screening among C. difficile toxin positive samples, will be cost effective for determination of high risk patients in the hospitals especially for developing countries.

Detection of both vanA & vanB genes in vanA phenotypes of Enterococci by Taq Man RT-PCR

Twenty seven isolates of vancomycin resistant Enterococci based on the disk diffusion and E- test have been screened; being found eight (0.3%) clinical isolates of vanA & vanB through Taq Man Real Time PCR assay. This study shows the presence of both vanA & vanB genotypes in vanA phenotypes clinical isolates in the three hospitals in Iran.

Evaluation of the iNtRON VRE vanA/vanB Real-Time PCR Assay for Detection of Vancomycin-Resistant Enterococci

BACKGROUND: Recently, the iNtRON VRE vanA/vanB real-time PCR (iNtRON; iNtRON Biotechnology, Korea) assay, a multiplex real-time PCR method, was introduced. In this prospective study, we compared the iNtRON assay with the Seeplex VRE ACE detection kit (Seeplex; Seegene, Korea), a conventional multiplex PCR assay. METHODS: A chromogenic agar-based culture, in which pre-selected vancomycin-resistant enterococci (VRE) was grown and subsequently plated on blood agar with vancomycin disks, was regarded as the reference method. A total of 304 consecutive rectal swab specimens were tested for VRE by culture and by iNtRON and Seeplex PCR assays. For the PCR assays, specimens were enriched for 16-24 hr before PCR. RESULTS: VRE were isolated from 44 (14.5%) specimens by chromogenic agar-based culture. The clinical sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the iNtRON assay were 100% (95% confidence interval: 89.8%-100%), 99.2% (96.9%-99.9%), 95.6% (83.6%-99.2%), and 100% (98.2%-100%), respectively, while those of the Seeplex assay were 97.7% (86.2%-99.9%), 99.6% (97.5%-99.9%), 97.7% (86.2%-99.9%), and 99.6% (97.5%-99.9%), respectively. The iNtRON assay had a detection limit of 3,159 copies/microL and 13,702 copies/microL for the vanA and vanB genes, respectively. No cross-reactivity was observed in 11 non-VRE bacterial culture isolates. CONCLUSIONS: The overall performance of the iNtRON assay was comparable to that of a chromogenic agar-based culture method for prompt identification of VRE-colonized patients in hospitals. This assay could be an alternative or supportive method for the effective control of nosocomial VRE infection.

The first report of the vanC1 gene in Enterococcus faecium isolated from a human clinical specimen

The vanC1 gene, which is chromosomally located, confers resistance to vancomycin and serves as a species marker for Enterococcus gallinarum. Enterococcus faecium TJ4031 was isolated from a blood culture and harbours the vanC1gene. Polymerase chain reaction (PCR) assays were performed to detect vanXYc and vanTc genes. Only the vanXYc gene was found in the E. faecium TJ4031 isolate. The minimum inhibitory concentrations of vancomycin and teicoplanin were 2 µg/mL and 1 µg/mL, respectively. Real-time reverse transcription-PCR results revealed that the vanC1and vanXYc genes were not expressed. Pulsed-field gel electrophoresis and southern hybridisation results showed that the vanC1 gene was encoded in the chromosome. E. faecalis isolated from animals has been reported to harbour vanC1gene. However, this study is the first to report the presence of the vanC1gene in E. faecium of human origin. Additionally, our research showed the vanC1gene cannot serve as a species-specific gene of E. gallinarum and that it is able to be transferred between bacteria. Although the resistance marker is not expressed in the strain, our results showed that E. faecium could acquire the vanC1gene from different species.