Proteomic characterization of vanA-containing Enterococcus recovered from Seagulls at the Berlengas Natural Reserve, W Portugal

Institute for Biotechnology and Bioengineering, Center of Genomics and Biotechnology, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal. .
Proteome Science (Impact Factor: 1.73). 09/2010; 8(1):48. DOI: 10.1186/1477-5956-8-48
Source: PubMed


Enterococci have emerged as the third most common cause of nosocomial infections, requiring bactericidal antimicrobial therapy. Although vancomycin resistance is a major problem in clinics and has emerged in an important extend in farm animals, few studies have examined it in wild animals. To determine the prevalence of vanA-containing Enterococcus strains among faecal samples of Seagulls (Larus cachinnans) of Berlengas Natural Reserve of Portugal, we developed a proteomic approach integrated with genomic data. The purpose was to detect the maximum number of proteins that vary in different enterococci species which are thought to be connected in some, as yet unknown, way to antibiotic resistance.
From the 57 seagull samples, 54 faecal samples showed the presence of Enterococcus isolates (94.7%). For the enterococci, E. faecium was the most prevalent species in seagulls (50%), followed by E. faecalis and E. durans (10.4%), and E. hirae (6.3%). VanA-containing enterococcal strains were detected in 10.5% of the 57 seagull faecal samples studied. Four of the vanA-containing enterococci were identified as E. faecium and two as E. durans. The tet(M) gene was found in all five tetracycline-resistant vanA strains. The erm(B) gene was demonstrated in all six erythromycin-resistant vanA strains. The hyl virulence gene was detected in all four vanA-containing E. faecium isolates in this study, and two of them harboured the purK1 allele. In addition these strains also showed ampicillin and ciprofoxacin resistance. The whole-cell proteomic profile of vanA-containing Enterococcus strains was applied to evaluate the discriminatory power of this technique for their identification. The major differences among species-specific profiles were found in the positions corresponding to 97-45 kDa. Sixty individualized protein spots for each vanA isolate was identified and suitable for peptide mass fingerprinting measures by spectrometry measuring (MALDI/TOF MS) and their identification through bioinformatic databases query. The proteins were classified in different groups according to their biological function: protein biosynthesis, ATP synthesis, glycolysis, conjugation and antibiotic resistance. Taking into account the origin of these strains and its relation to infectious processes in humans and animals, it is important to explore the proteome of new strains which might serve as protein biomarkers for biological activity.
The comprehensive description of proteins isolated from vancomycin-resistant Enterococcus faecium and E. durans may provide new targets for development of antimicrobial agents. This knowledge may help to identify new biomarkers of antibiotic resistance and virulence factors.

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    • "Acquired resistance determinants have indeed been found in commensal microbiota of wild birds. As migratory birds travel great distances and inhabit a variety of environments, they could potentially act as reservoirs of antibiotic-resistant bacteria with a wide dissemination range [3]. Similarly, other wild animals with extensive habitat ranges might spread antibiotic resistance throughout the environment. "
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    • "Within the heterogeneous class of birds, two groups seem to be in the focus of ESBL-E. coli and VRE carriage in wildlife: birds of prey (Costa et al., 2006; Pinto et al., 2010; Radhouani et al., 2010a,b; Silva et al., 2011a) and waterfowl/water related species (Poeta et al., 2008; Bonnedahl et al., 2009; Dolejska et al., 2009; Guenther et al., 2010a; Hernandez et al., 2010; Literak et al., 2010a; Radhouani et al., 2010c; Simões et al., 2010; Garmyn et al., 2011). However, recent studies in Passeriformes have also described a significant incidence of VRE (Silva et al., 2011a, 2012; Oravcova et al., 2013a,b). "
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    • "Studies concerning the incidence of resistant enterococci and E. coli isolates in wild animals are available in the literature (Caprioli et al. 1991; Lillehaug et al. 2005; Poeta et al. 2005; Costa et al. 2008; Schierack et al. 2009; Silva et al. 2010; Allen et al. 2011; Radhouani et al. 2012). Still, the flow of resistant microorganisms and resistant genes from livestock and humans to wildlife, or vice-versa, remains poorly understood despite the fact that wild animals may act as reservoirs of resistant genetic elements that could be spread across the environment (Sørum and Sunde 2001; Aarestrup et al. 2008; Radhouani et al. 2010b). The Portuguese population of Iberian wolf (Canis lupus signatus) is endangered (Cabral et al. 2008). "
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