Detection of MRSA ST3061-t843-mecC and ST398-t011-mecA in white stork nestlings exposed to human residues.
OBJECTIVE
The objective of this study was to analyse the prevalence of tracheal carriage of Staphylococcus aureus/MRSA in storks and to study the resistance and virulence genes in the obtained isolates.


METHODS
Tracheal samples from 92 stork nestlings of two landfill-associated and two natural-habitat colonies were inoculated in specific media for S. aureus and MRSA recovery. Antimicrobial susceptibility was tested, and the presence of resistance, virulence and immune evasion cluster (IEC) genes was analysed by PCR. S. aureus isolates were characterized by spa and agr typing. Staphylococcal cassette chromosome (SCC) mec type was determined for mecC-positive isolates, and MLST was performed for 17 selected S. aureus isolates.


RESULTS
S. aureus isolates were identified in 32/92 samples (34.8%), and 38 isolates were recovered. The prevalence of S. aureus was higher in nestlings from landfills (24/43, 55.8%) than in those from natural habitats (8/49, 16.3%). Three birds from landfill-associated colonies carried MRSA, two with mecA-positive strains [clonal complex (CC) 5-spa-t002 and CC398-spa-t011] and one with a mecC-positive strain [sequence type (ST) 3061-CC130-spa-t843-agr-III-SCCmecXI). None of the MRSA isolates presented IEC genes. Thirty-five MSSA isolates, which showed 18 different spa types (ascribed to CC5, CC7, CC22, CC30, CC45, CC59, CC133 and CC398), were obtained. The agr types detected were I (63%), II (29%) and III (8%). Resistance and virulence genes identified in MSSA were blaZ (n = 25), erm(T) (n = 9), erm(A) (n = 1), tet(M) (n = 2), fexA (n = 3), str (n = 2), tst (n = 2), eta (n = 1) and cna (n = 15). The IEC types B, C, D and G were found in MSSA isolates, and two new STs were identified (ST3060 and ST3061).


CONCLUSIONS
White storks are frequently tracheal carriers of S. aureus, including ST398 isolates. MRSA isolates of lineages CC398-mecA and CC130-mecC were detected in storks from landfill-associated colonies exposed to human residues.
Area of Biochemistry and Molecular Biology, University of La Rioja, Logroño, Spain.
Paula
P
Gómez
Area of Biochemistry and Molecular Biology, University of La Rioja, Logroño, Spain.
Carmen
C
Lozano
SaBio, Spanish Wildlife Research Institute IREC (CSIC-UCLM-JCCM), Ciudad Real, Spain.
Mari Cruz
MC
Camacho
SaBio, Spanish Wildlife Research Institute IREC (CSIC-UCLM-JCCM), Ciudad Real, Spain.
José-Francisco
JF
Lima-Barbero
SaBio, Spanish Wildlife Research Institute IREC (CSIC-UCLM-JCCM), Ciudad Real, Spain.
José-Manuel
JM
Hernández
Area of Biochemistry and Molecular Biology, University of La Rioja, Logroño, Spain.
Myriam
M
Zarazaga
SaBio, Spanish Wildlife Research Institute IREC (CSIC-UCLM-JCCM), Ciudad Real, Spain.
Úrsula
Ú
Höfle
Area of Biochemistry and Molecular Biology, University of La Rioja, Logroño, Spain carmen.torres@unirioja.es.
Carmen
C
Torres
D000818:Animals; D001717:Birds; D002353:Carrier State / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D005798:Genes, Bacterial; D005838:Genotype; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D016133:Polymerase Chain Reaction; D015995:Prevalence; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D014132:Trachea / Q000382:microbiology*