Clonal Structure and Antibiotic Resistance of Enterococcus spp. from Wild Birds in Poland

The purpose of this study was to analyze the antibiotic resistance and genetic diversity of 27 enterococci (Enterococcus faecium, Enterococcus hirae, Enterococcus durans, and Enterococcus casseliflavus) isolated from wild bird species. Resistance to lincomycin was most common, followed by erythromycin, ciprofloxacin, tetracyclines, high level of aminoglycoside, and β-lactam antibiotics. No vancomycin- and chloramphenicol-resistant isolates were identified. The antibiotic resistance was linked to the tet(M), tet(L), erm(A), erm(B), msr(A/B), pbp5, ant(6)-Ia, and aph(3')-IIIa genes. Tn916/Tn1545-like transposons were detected. The high-level resistance to gentamicin was associated with the presence of gene aph(2″)-Id. All 18 E. faecium isolates were divided into 16 pulsotypes and 17 sequence types (STs), among which 7 STs were newly assigned (ST1266-ST1272). A majority of E. faecium isolates possess multilocus sequence typing profiles belonging to clonal complex 17 (CC17), the major epidemic lineage responsible for nosocomial infections. Two ST17 and newly described ST1267 and ST1271 (an SLV and DLV of ST17, respectively) of E. faecium isolates carried the type 1 allele of the housekeeping gene purK detected in hospital-related strains. Our results indicated that wild birds could be a source of resistant E. faecium isolates, belonging to CC17 and may represent a hazard to human health by transmission of these isolates.