RESUMO
We identified a novel van gene cluster in a clinical Enterococcus faecium isolate with vancomycin minimum inhibitory concentration (MIC) of 4 µg/mL. The ligase gene, vanP, was part of a van operon cluster of 4,589 bp on a putative novel integrative conjugative element located in a ca 98 kb genomic region presumed to be acquired by horizontal gene transfer from Clostridiumscidens and Roseburia sp. 499. Screening for van genes in E. faecium strains with borderline susceptibility to vancomycin is important.
Assuntos
Enterococcus faecium , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Bélgica , Enterococcus faecium/genética , Humanos , Família Multigênica , Resistência a Vancomicina/genéticaRESUMO
Five commercially available selective agar were evaluated regarding sensitivity and specificity to detect vancomycin-resistant Enterococcus (E.) faecium. Altogether 187 E. faecium strains were included, comprising 119 van-carrying strains (phenotypically vancomycin-resistant n = 105; phenotypically vancomycin-susceptible VVE-B n = 14) and 68 vancomycin-susceptible isolates. Limit of detection was calculated for each selective agar for pure cultures, stool suspensions and artificial rectal swabs. After 24-h incubation sensitivity ranged between 91.6% and 95.0%. It increased in 2 out of 5 agar after 48-h incubation. Specificity ranged between 94.1% and 100% and was highest after 24 h in 4 out of the 5 agar. Sensitivity of van-carrying phenotypically vancomycin-resistant strains was higher after 24 h (97.1-100%) and 48 h (99.1-100%) when compared to van-carrying strains that tested vancomycin-susceptible (50.0-57.1% after both incubation periods). Overall, chromID VRE, CHROMagar VRE and Brilliance VRE demonstrated the highest detection rates after 24 h. Detection rates of Chromatic VRE and VRESelect improved after 48 h. Adjustment of incubation time depending on the applied media may be advised. As detection of VVE-B was impeded with all selective agar, screening for vancomycin-resistant enterococci relying solely on selective media would not be recommended for critical clinical samples, but rather in combination with molecular methods to improve detection of these strains. Furthermore, stool samples were demonstrated to be superior to rectal swabs and should be favoured, if possible, in screening strategies.
RESUMO
OBJECTIVE: To investigate the occurrence of vancomycin-resistant enterococci (VRE) isolated from patients in Peking Union Medical College Hospital, Beijing, China from 2011 to 2017, and to evaluate their resistance mechanisms and genetic relatedness. METHODS: All isolates were identified using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF). Antibiotic susceptibility testing was performed using the broth microdilution method. Molecular characterization were detected by PCR and sequencing. Genotyping of VRE isolates was performed by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) analysis. Virulence genes were detected by multiplex PCR. RESULTS: A total of 87 consecutive VRE were collected, including 84 isolates of vancomycin resistant Enterococcus faecium (VREfm) and 3 isolates of Enterococcus faecalis (VREfs). Urine (40.2%, 35/87) and blood (17.2%, 15/87) were the most commonly specimens. All VREfm isolates were resistant to ampicillin, and were susceptible to daptomycin, linezolid and tigecycline. The resistant rate of teicoplanin was 47.6%. All of the VREfm isolates carried the vanA gene, no isolates carried vanB. 11.9% (10/84) VREfm isolates carried both vanA and vanM. Among them, 76.2% (64/84) and 66.7% (56/84) carried esp and hyl, respectively. The 3 vancomycin resistant E. faecalis (VREfs) isolates were varied, and only one carried vanB. A total of 3 and 18 STs were detected among VREfs and VREfm strains, respectively. PFGE results indicated a genetic diversity among VREfm isolates. CONCLUSION: This study confirms that VREfm isolates associated with ST78 were the main epidemic lineage responsible for nosocomial infections in China, as were also observed in other nations worldwide.
Assuntos
Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Infecções por Bactérias Gram-Positivas/epidemiologia , Infecções por Bactérias Gram-Positivas/microbiologia , Enterococos Resistentes à Vancomicina/genética , Enterococos Resistentes à Vancomicina/isolamento & purificação , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Pequim/epidemiologia , DNA Bacteriano/genética , Enterococcus faecalis/classificação , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/genética , Enterococcus faecalis/isolamento & purificação , Enterococcus faecium/classificação , Enterococcus faecium/efeitos dos fármacos , Enterococcus faecium/genética , Enterococcus faecium/isolamento & purificação , Variação Genética , Genótipo , Humanos , Testes de Sensibilidade Microbiana , Epidemiologia Molecular , Tipagem Molecular , Reação em Cadeia da Polimerase Multiplex , Centros de Atenção Terciária , Resistência a Vancomicina/genética , Enterococos Resistentes à Vancomicina/classificação , Enterococos Resistentes à Vancomicina/efeitos dos fármacos , Fatores de Virulência/genéticaRESUMO
We have isolated 6 vancomycin resistant (VR) Enterococcus faecium and 5 VR-E. gallinarum. Vancomycin resistant enterococcus (VRE) isolates were resistant to multi-drugs, but susceptible to linezolid and quinupristin/dalfopristin. VRE isolates showed 10 VanA phenotypes and 1 VanB phenotype (E. gallinarum). However, all of them showed vanA genotype. vanA gene was detected on both genomic and plasmid DNA from all VRE isolates. Almost of VR-E. faecium had IS1216V which is worldwide type and almost of VR-E. gallinarum had IS1542 which is European type. IS1216V and IS1542 genes were not related with antibiotic types of VRE. Copy numbers of vanA were decreased in VRE with IS1216V or IS1542 but not in VRE with both ISs in broth without vancomycin. The copy numbers of vanA were significantly decreased in VanB phenotype of VRE with IS1542 in broth without vancomycin. Copy numbers of vanA were recovered in the presence of vancomycin. Growth time of reference E. faecium is faster than that of reference E. faecalis when cultured in the broth containing vancomycin. Reference strains cultured in the broth containing vancomycin showed intermediate resistance or resistance to antibiotics without acquisition of van genes. Naturally, multidrug-resistant E. faecium might be fast adapted in the presence of vancomycin compared to E. faecalis. Taken together, VanA phenotype E. gallinarum as well as E. feacium have been increasing in nosocomial infection and showed acquired inducible resistance. E. faecium and E. faecalis showed intermediate resistance in long exposure of vancomycin without acquisition of vanA.