title: Prevalence and characterization of methicillin susceptible Staphylococcus aureus ST398 isolates from retail foods.
abstract: In this study, we explored the prevalence of Staphylococcus aureus (S. aureus) ST398 in retail foods and then investigated for their virulence and antimicrobial resistance genetic background. Fourteen out of 5103 (0.27%) samples were positive for methicillin susceptible S. aureus (MSSA) ST398. Resistance was most frequently observed to penicillin (PEN) (100%), followed by trimethoprim (TMP), erythromycin (ERY) and ampicillin (AMP) (each 86.7%), clindamycin (CLD, 80.0%), and tetracycline (TET, 26.7%). All ST398 isolates were susceptible to amikacin, chloramphenicol, cefoxitin, gentamicin, oxacillin, and vancomycin. Two predominant resistance patterns including TMP-ERY-CLD-PEN-AMP (60.0%) and TMP-ERY-TET-CLD-PEN-AMP (20.0%) were identified. Isolates harbored blaZ (86.7%) gene, followed by tet(L) and linA/linA' (each 46.7%), ermB and msrA (each 33.3%), aph(3')-IIIa and dfrK (each 26.7%), tet(K) (20.0%), ant(4')-Ia, ermA and emrC (each 13.3%) and cat::pC221 (6.7%). No isolate carried mecA, tet(M), tet(O), fexA, aac(6')/aph(2″), cfr, ermT, msrB, cat::pC194, cat::pC223, catpIp-501, dfrD, dfrG and dfrS1 genes. For virulence genes, hld (73.3%), seb and sed (each 66.7%), hla (60.0%), lukPV (33.3%), sej (26.7%), lukED and seg (each 3.3%) were detected. None of isolates contained sea, sec, see, seh, sei, tst, eta, etb, sek-ser, seu, lukM, hlg, and hlgv genes. Four spa types were found, including t571 (6/15), t034 (4/15), t2876 (3/15) and t1250 (2/15). All strains were non-typeable for agr locus. Our findings indicated that MSSA ST398 isolates had a low prevalence rate in retail foods, and these isolates harbored multiple virulence and antimicrobial resistance genes, and exhibited multiple antimicrobial resistance. Further studies are required to elucidate the possible role of MSSA ST398 as a source of human infection.
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Guanghui
authors.initials: G
authors.lastname: Li
authors.affiliation: College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
authors.forename: Congming
authors.initials: C
authors.lastname: Wu
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China. Electronic address: xinwang7516@nwsuaf.edu.cn.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China; Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, USA.
authors.forename: Jianghong
authors.initials: J
authors.lastname: Meng
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D005516:Food Microbiology; D008826:Microbial Sensitivity Tests; D015995:Prevalence; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D037521:Virulence Factors / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D037521:Virulence Factors
keywords: Antimicrobial resistance; Resistance and virulence genes; Retail foods; S. aureus ST398