title: Antimicrobial susceptibility and virulence characteristics of Salmonella enterica Typhimurium isolates from healthy and diseased pigs in Korea.
abstract: This study compared the antimicrobial susceptibility and prevalence of virulence genes in Salmonella enterica Typhimurium isolated from healthy and diseased pigs in Korea. A total of 456 Salmonella Typhimurium isolated from healthy (n = 238) and diseased (n = 218) pigs between 1998 and 2011 were investigated. In total, 93.4% of the Salmonella Typhimurium isolates were resistant to at least one antimicrobial agent tested. The isolates were most often resistant to tetracycline (85.7%), followed by streptomycin (83.6%), nalidixic acid (67.3%), ampicillin (49.3%), chloramphenicol (42.8%), and gentamicin (37.1%). Moreover, multidrug resistance phenotype and resistance to ampicillin, florfenicol, gentamicin, nalidixic acid, neomycin, streptomycin, and tetracycline were significantly higher (P < 0.01) among Salmonella Typhimurium isolates from the diseased pigs compared with those from the healthy pigs. The most common resistance pattern observed in both groups of isolates was streptomycin-tetracycline. Overall, more than 96% of the isolates tested possessed invA, spiA, msgA, sipB, prgH, spaN, tolC, lpfC, sifA, sitC, and sopB virulence genes. The prevalence of orgA, pagC, and iroN were 50.2, 74.1, and 91.0%, respectively, whereas isolates carrying cdtB (1.5%), pefA (7.0%), and spvB (14.9%) were identified much less frequently. Furthermore, the prevalence of invA, lpfC, orgA, pagC, and iroN was significantly higher (P < 0.01) among the isolates from the diseased pigs than in isolates from the healthy pigs. Our results demonstrated that, among diseased pigs, there was significantly higher resistance to some antimicrobials and greater prevalence of some virulence genes than in healthy pigs, indicating the role these factors play in pathogenesis. Multidrug-resistant Salmonella isolates that carry virulence-associated genes are potentially more dangerous and constitute a public health concern. Thus, continuous surveillance of antimicrobial resistance and virulence characteristics in Salmonella is essential.
authors.affiliation: Bacterial Disease Division, Animal and Plant Quarantine Agency, 175 Anyang-ro, Anyang-6 dong, Manan-gu, Anyang, Gyeonggi-do, 430-757, Republic of Korea.
authors.forename: Migma Dorji
authors.initials: MD
authors.lastname: Tamang
authors.affiliation: Bacterial Disease Division, Animal and Plant Quarantine Agency, 175 Anyang-ro, Anyang-6 dong, Manan-gu, Anyang, Gyeonggi-do, 430-757, Republic of Korea.
authors.forename: Mamata
authors.initials: M
authors.lastname: Gurung
authors.affiliation: Bacterial Disease Division, Animal and Plant Quarantine Agency, 175 Anyang-ro, Anyang-6 dong, Manan-gu, Anyang, Gyeonggi-do, 430-757, Republic of Korea.
authors.forename: Hyang-Mi
authors.initials: HM
authors.lastname: Nam
authors.affiliation: Bacterial Disease Division, Animal and Plant Quarantine Agency, 175 Anyang-ro, Anyang-6 dong, Manan-gu, Anyang, Gyeonggi-do, 430-757, Republic of Korea.
authors.forename: Dong Chan
authors.initials: DC
authors.lastname: Moon
authors.affiliation: Bacterial Disease Division, Animal and Plant Quarantine Agency, 175 Anyang-ro, Anyang-6 dong, Manan-gu, Anyang, Gyeonggi-do, 430-757, Republic of Korea.
authors.forename: Geum-Chan
authors.initials: GC
authors.lastname: Jang
authors.affiliation: Bacterial Disease Division, Animal and Plant Quarantine Agency, 175 Anyang-ro, Anyang-6 dong, Manan-gu, Anyang, Gyeonggi-do, 430-757, Republic of Korea.
authors.forename: Suk-Chan
authors.initials: SC
authors.lastname: Jung
authors.affiliation: Bacterial Disease Division, Animal and Plant Quarantine Agency, 175 Anyang-ro, Anyang-6 dong, Manan-gu, Anyang, Gyeonggi-do, 430-757, Republic of Korea. imsk0049@korea.kr.
authors.forename: Suk-Kyung
authors.initials: SK
authors.lastname: Lim
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D008826:Microbial Sensitivity Tests; D056910:Republic of Korea; D012481:Salmonella Infections, Animal / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents