The marine environment as a reservoir of enterococci carrying resistance and virulence genes strongly associated with clinical strains. Issue 2 (25th November 2013)

• Record Type: Journal Article
• Authors: Di Cesare, Andrea; Pasquaroli, Sonia; Vignaroli, Carla; Paroncini, Paolo; Luna, Gian Marco; Manso, Esther; Biavasco, Francesca
• Is Part Of: Environmental microbiology reports. Volume 6:Issue 2(2014)
• Page Start: 184
• Page End: 190
• Publication Date: 2013-11-25
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; Electronic journals; 579.17
• DOI: 10.1111/1758-2229.12125
• Languages: English
• ISSNs: 1758-2229

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>To gain insights into the relationships and the genetic exchange among environmental and clinical enterococci, 59 strains (29 from marine aquaculture sites and 30 from clinical settings) resistant to tetracycline, erythromycin, ampicillin and/or gentamicin were analysed for the antibiotic resistance <italic>tet(M)</italic>, <italic>tet(L)</italic>, <italic>tet(O)</italic>, <italic>erm(A)</italic>, <italic>erm(B)</italic>, <italic>mef blaZ</italic>, <italic>aac</italic><italic>(6′)‐</italic><italic>Ie aph</italic><italic>(2″)‐</italic><italic>Ia</italic> and virulence <italic>gelE</italic>, <italic>cylB</italic>, <italic>efaA</italic> and <italic>esp</italic> genes, and for the copper resistance gene <italic>tcrB</italic>. Antibiotic resistance and virulence genes were detected more frequently in clinical than in environmental enterococci; the opposite was true for copper resistance. Conjugation experiments demonstrated the transfer of antibiotic resistance genes from marine to clinical enterococci in interspecific mating and the uncommon joint transfer of <italic>tet(L)</italic> and <italic>erm(B)</italic>. Enterobacterial repetitive intergenic consensus polymerase chain reaction typing evidenced a cluster (90% similarity) encompassing strains carrying multiple antibiotic resistance genes from both sets; the others marine isolates exhibited polyclonality and bore <italic>tcrB</italic>. Our results demonstrate that antibiotic‐resistant marine enterococci bear antibiotic resistance genes transferable to humans and suggest that copper resistance, not observed among clinical strains, may be useful for survival in the environment, whereas virulence genes likely confer no advantage to enterococcal populations adapted to a lifestyle outside the host.</p> </abstract>