A Clonal Lineage of VanA-Type Enterococcus faecalis Predominates in Vancomycin-Resistant Enterococci Isolated in New Zealand

Abstract

Avoparcin was used as a feed additive in New Zealand broiler production from 1977 until June 2000. We report here on the effects of the usage and discontinuation of avoparcin on the prevalence of vancomycinresistant enterococci (VRE) in broilers. Eighty-two VRE isolates were recovered from poultry fecal samples between 2000 and mid-2001. VRE isolates were only obtained from broiler farms that were using, or had previously used, avoparcin as a dietary supplement. Of these VRE isolates, 73 (89%) were VanA-type Enterococcus faecalis and nine (11%) were VanA-type Enterococcus faecium. All E. faecalis isolates were found to have an identical or closely related pulsed-field gel electrophoresis (PFGE) pattern of SmaI-digested DNA and were susceptible to both ampicillin and gentamicin. The PFGE patterns of the nine E. faecium isolates were heterogeneous. All VRE contained both the vanA and ermB genes, which, regardless of species or PFGE pattern, resided on the same plasmid. Eighty-seven percent of the VRE isolates also harbored the tet(M) gene, while for 63 and 100%, respectively, of these isolates, the avilamycin and bacitracin MICs were high (>256 g/ml). Five of eight vancomycin-resistant E. faecalis isolates recovered from humans in New Zealand revealed a PFGE pattern identical or closely related to that of the E. faecalis poultry VRE isolates. Molecular characterization of Tn1546-like elements from the VRE showed that identical transposons were present in isolates from poultry and humans. Based on the findings presented here, a clonal lineage of VanA-type E. faecalis dominates in VRE isolated from poultry and humans in New Zealand.

Current Trends of Emergence and Spread of Vancomycin-Resistant Enterococci

“…However, community carriage linked to a consumption of imported and contaminated food cannot be excluded. Studies performed in New Zealand described a www.intechopen.com supposed dissemination of vanA-type resistance among E. faecalis strains rather then E. faecium in a background of generally low level of vancomycin resistance (Manson et al, 2003a;Manson et al, 2003b). VRE epidemiology in other Australasian countries reflects a similar scenario as in Europe or Northern America with vanA-type resistance highly prevalent among E. faecium.…”

“…Exchange of resistant strains among different ecosystems is less probable due to the supposed ecovar association, especially among hospital-associated E. faecium strains (see chapter 5), although dissemination across host barriers of vancomycin-and multi-resistant enterococci was described anecdotally, especially for the less strongly host-adapted E. faecalis strains (Manson et al, 2003a;Manson et al, 2003b;Manson et al, 2004;Agerso et al, 2008;Larsen et al, 2010;Hammerum et al, 2010;Freitas et al, 2011a). Vancomycin resistance among enterococci most probably spreads via a dissemination of mobile genetic elements of variants of the vanA-type element Tn1546 mostly located on mobilizable or conjugative plasmids (Sletvold et al, 2007;Novais et al, 2008;Sletvold et al, 2008;Freitas et al, 2009;Rosvoll et al, 2009;Sletvold et al, 2010;Laverde Gomez et al, 2011;Werner et al, 2011b;Freitas et al, 2011b).…”

“…Recent in vitro studies have linked point mutations rather than deletions and duplications to a corresponding erm(B) constitutive phenotype in enterococci (Min et al, 2008). The erm(B) determinant is widespread among enterococci, especially E. faecium and E. faecalis and is part of many multi-resistance plasmids and often linked to Tn1546-like vanA elements (Aarestrup et al, 2000a;Borgen et al, 2002;Werner et al, 2003a;Werner et al, 2003b;Manson et al, 2003b;Werner et al, 2006;Laverde Gomez et al, 2010). Another mechanism mediating macrolide (and streptogramin B) resistance is conferred by the msrA-C genes Kerr et al, 2005) whereas msrC is discussed as a species-specific property in E. faecium (Singh et al, 2001;Werner et al, 2001b) shown to encode erythromycin and clarithromycin resistance when expressed in S. aureus .…”

Molecular Analysis of BcrR, a Membrane-bound Bacitracin Sensor and DNA-binding Protein from Enterococcus faecalis

“…Restriction or DNA-modifying enzymes and other molecular biology reagents were obtained from Roche Diagnostics or New England Biolabs. Genomic DNA of E. faecalis was isolated as previously described (30). Transformation of E. faecalis cells grown in the presence of glycine was performed as described by Shepard and Gilmore (29).…”

Characterization of a Vancomycin-Resistant Enterococcus faecalis (VREF) Isolate from a Dog with Mastitis: Further Evidence of a Clonal Lineage of VREF in New Zealand

“…VRE have been isolated from poultry sources in New Zealand (18); however, VRE causing infection in the clinical situation are rare (17). Chromosomal macrorestriction analysis of VRE isolates from poultry and humans in New Zealand has demonstrated that a dominant clonal lineage of vancomycin-resistant Enterococcus faecalis (VREF) exists (18). In this report, we describe the first VREF isolate (AR01/DG) recovered from a dog in New Zealand and show that it belongs to the same clonal lineage described in poultry and humans.…”