title: Detection, molecular characterization, and clonal diversity of methicillin-resistant Staphylococcus aureus CC398 and CC97 in Spanish slaughter pigs of different age groups.
abstract: The objective of this study was to determine the frequency of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) in slaughter pigs, to characterize the recovered isolates, and to investigate their genomic relatedness. Nasal swabs were collected from 53 finishing-pigs (F-pigs) and 53 suckling-piglets (S-piglets) at two different abattoirs in La Rioja (Northern Spain) coming from six production holdings. MRSA isolates were characterized by spa−, agr−, SCCmec−, and multilocus sequence typing, pulsed-field gel electrophoresis (PFGE)-ApaI, toxin gene profiling, antimicrobial susceptibility, and determination of antimicrobial resistance genes. MRSA isolates were recovered from 11 F-pigs (14 isolates) and 26 S-piglets (30 isolates). Forty of the 44MRSA presented the spa-types t011, t108, t1197, and t2346, which corresponded to the sequence type ST398 and to the clonal complex CC398. Interestingly, the remaining four isolates from F-pigs presented the spa-type t3992, and they were ascribed to a new sequence type named ST1379 (a single-locus variant of ST97), which was included in clonal complex CC97. Five PFGE-ApaI clusters with up to nine individual patterns detected among our MRSA and low genomic relatedness was observed between F-pig and S-piglet isolates. All MRSA were positive for hla, hld, and hlg hemolysin genes. ST1379 isolates harbored eta, lukE/D, and hlg-2 toxin genes, whereas ST398 isolates were positive for hlb. A great variety of distinct resistance gene patterns were observed, most of them coming from F-pig isolates. MRSA virulence properties seem to be dependent of the isolate clonal lineage. This study showed that slaughter pigs are frequently colonized by MRSA CC398; moreover, the detection of strains belonging to CC97 underlines that other lineages are also able to spread in livestock. Further studies should assess the risk of CC398 and non-CC398 MRSA to enter the food chain as well as the human health implications.
authors.affiliation: Departamento de Agricultura y Alimentación, Universidad de La Rioja, Madre de Dios 51, Logroño, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Gómez-Sanz
authors.forename: Carmen
authors.initials: C
authors.lastname: Torres
authors.forename: Carmen
authors.initials: C
authors.lastname: Lozano
authors.forename: Rocío
authors.initials: R
authors.lastname: Fernández-Pérez
authors.forename: Carmen
authors.initials: C
authors.lastname: Aspiroz
authors.forename: Fernanda
authors.initials: F
authors.lastname: Ruiz-Larrea
authors.forename: Myriam
authors.initials: M
authors.lastname: Zarazaga
mesh_terms: D000003:Abattoirs; D000375:Aging; D000818:Animals; D001427:Bacterial Toxins / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D009296:Nasal Cavity / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D013030:Spain; D013552:Swine / Q000382:microbiology*
chemical_list: D001427:Bacterial Toxins