Vancomycin resistant Enterococcus spp. from crows and their environment in metropolitan Washington State, USA: Is there a correlation between VRE positive crows and the environment?

Vancomycin-resistant enterococci [VRE] have been isolated from municipal, hospital and agricultural wastewater, recreational beaches, wild animals, birds and food animals around the world. In this study, American crows (Corvus brachyrhynchos) from sewage treatment plants (WWTP), dairy farms, and a large roost in a restored wetland with corresponding environmental samples were cultured for VRE. A total of 245 samples [156 crows, 89 environmental] were collected and screened for acquired vanA, vanB and/or intrinsic vanC1 genes. Samples were enriched overnight in BHI supplemented with 20µg/mL aztreonam, 4µg/mL vancomycin and plated on m-Enterococcus agar media supplemented with 6µg/mL vancomycin. Selected colonies were grown on BHI media supplemented with 18µg/mL vancomycin. Of these, 24.5% of the crow and 55% the environmental/cow samples were VRE positive as defined by Enterococcus spp. able to grow on media supplemented with 18µg/mL vancomycin. A total of 122 VRE isolates, 43 crow and 79 environmental isolates were screened, identified to species level using 16S sequencing and further characterized. Four vanA E. faecium and multiple vanC1 E. gallinarum were identified from crows isolated from three sites. E. faecium vanA and E. gallinarum vanC1 along with other Enterococcus spp. carrying vanA, vanB, vanC1 were isolated from three environments. All enterococci were multidrug resistant. Crows were more likely to carry vanA E. faecium than either the cow feces or wetland waters/soils. Comparing E. gallinarum vanC1 from crows and their environment would be useful in determining whether crows share VRE strains with their environment.

An Enterococcus gallinarum Strain Carrying Both vanA and vanC1 Genes / 대한임상병리학회지

Enterococcus gallinarum carrying both vanA and vanC1 genes were detected from a surveillance culture from a patient staying at the surgical intensive care unit for a few years. E. gallinarum, SI04, was highly resistant to vancomycin (MIC of >or=256ng/mL) and teicoplanin (MIC of >or=256ng/mL). Multiplex PCR for vanA, vanB, vanC1 and vanC2/3 genes revealed SI04 to be positive for both vanA and vanC1 genes. This finding supports the fact that genotyping is needed to classify vancomycin-resistant enterococci (VRE). This is the first report on VanC VRE accompanying vanA gene in Korea.

Biochemical Tests for Differential Identification of Enterococci with VanC phenotype / 대한임상미생물학회지

BACKGROUND: Pigment production and acidification of ribose are most frequently used biochemical tests for the differentiation of three enterococcal species carrying vanC genes such as Enterococcus gallinarum, Enterococcus casseliflavus, and Enterococcus flavescens. However, pigment production may occasionally be negative in E. casseliflavus, and some of E. casseliflavus may be negative or delayed reaction with ribose fermentation test. So, we performed this study to find out biochemical tests capable of distinguishing the strains possessing vanC genotypes. METHOD: A total of 17 enterococci composed of 14 clinical isolates with motility or pigment positive strains and three ATCC strains(E. gallinarum ATCC 49573, E. casseliflavus ATCC 25788, and E. flavescens ATCC 49997) Were tested by multiplex PCR of the vanC genes(vanC-1, vanC-2 and vanC-3)and various biochemical tests. RESULTS: Among the 17 isolates including three ATCC control strains, four were genotyped as VanC-1, 11 were VanC-2, one were vanC-2/3, and any of vanC genes were not detected in one clinical isolate, respectively, Among the enterococci with vanC genotype, acid production from alphaD-cyclodextrin and hippurate hydrolysis were positive only in VanC-1 gneotype(E. gallinarum), acid production from glycerol and methyl-alpha-D-mannopyranoside were positive only in vanC-2 genotype(E. casseliflavus), and acid production from rhamnose and pigment production were negative only in VanC-1 genotype. Acid production from alphaD-cyclodextrin was negative only in vanC-2 genotype. The positive rate of ribose fermentation of VanC-1, VanC-2, and VanC-2/3(E. flavescens) genotype were 100%, 82%, and 0%, respectively. CONCLUSION: Acid production from rhamnose, alphaD-cyclodextrin, betaD-cyclodextrin, glycerol and methly-alphaD-mannopyranoside, pigment production, and hippurate hydrolysis test were useful biochemical tests for differentitating E. gallinarum form E. casseliflavus. The production of acid from alphaD-cyclodextrin, glycerol, methyl-alpha-D-mannopyranoside and were suitable biochemical tests for differentiating E. casseliflavus from E. flavescens.

Vancomycin-resistant Enterococci: Incidence, Antimicrobial Susceptibility, and Resistance Genotypes / 대한임상병리학회지

BACKGROUND: Infections caused by vancomycin-resistant enterococci (VRE) are becoming increasingly prevalent throughout the world. VRE can spread by direct patient-to-patient contact as well as on the hands of personnel and contaminated environmental surfaces. The purpose of this study was to examine the incidence of VRE among total enterococci from clinical specimen and investigate the antimicrobial characteristics and resistance genotypes of isolated VRE. METHODS: A total of 790 enterococcal isolates from patients over a period of 12 months were screened for vancomycin resistance using brain heart infusion agar plates supplemented with 6 g/mL of vancomycin. The incidence of VRE among enterococcal isolates was calculated from microbiology statistics program. Twenty three isolates of VRE were tested for minimal inhibitory concentrations (MIC) of vancomycin, penicillin, and gentamicin and resistance genotypes. RESULTS: In the first half period, the incidence of VRE was 1.9%, and in the second half, the incidence increased to 7.7%. Thirteen strains were found to be highly resistant to vancomycin, penicillin and gentamicin (MIC, >128 g/mL). According to the direct PCR analyses, the frequency of vanB, vanC1, and vanC2 types was 13, 7, and 3 strains, respectively. CONCLUSIONS: Continued vigilance, strict enforcement of infection control, and curtailment of vancomycin use seem to be our best approaches to controlling this increasingly important problem. For this purposes, accurate and timely detection of vancomycin-resistance and periodic investigation for incidence are essential.