title: Antimicrobial susceptibility, tetracycline and erythromycin resistance genes, and multilocus sequence typing of Streptococcus suis isolates from diseased pigs in China.
abstract: Streptococcus suis (S. suis) is an emerging zoonotic pathogen causing significant economic losses in the swine industry. Here, we investigated the antimicrobial susceptibility, associated antibiotic-resistant determinants and sequence type (ST) of S. suis isolates from diseased pigs in China from 2008 to 2010. Serotype 2 was the most frequently observed strain (n=95) among the 106 S. suis strains collected, followed by serotypes 3 (n=3), 5 (n=3), 4 (n=2), 7 (n=1), 11 (n=1) and 28 (n=1). Multilocus sequence typing analysis revealed that ST1 (n=21) and ST7 (n=74) were the predominant STs, and serotype 2 was found to be significantly correlated with ST7 (P=0.017, Fisher's exact test) and CC1 (P=0.024, Fisher's exact test). The antimicrobial susceptibility results indicated that the antibiotic resistance rate was highest for tetracycline (99.1%), followed by azithromycin (68.9%), erythromycin (67.9%), clindamycin (67.9%), trimethoprim/sulfamethoxazole (16%), levofloxacin (2.8%), chloramphenicol (1.9%), cefaclor (0.9%) and ceftriaxone (0.9%). Antibiotic-resistant genes tet(M), tet(O), tet(O/W/32/O), tet(O/32/O), tet(S), tet(W), tet(L), tet(40), erm(B), mef(A/E) and msr(D) could be detected, and several tandem organizations of antibiotic resistance genes were also found in this study. In conclusion, S. suis strains isolated from diseased pigs in China were less diverse and multi-drug resistant.
authors.affiliation: Unit of Animal Infectious Diseases, National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430000, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Yajing
authors.initials: Y
authors.lastname: Song
authors.forename: Zigong
authors.initials: Z
authors.lastname: Wei
authors.forename: Hongkui
authors.initials: H
authors.lastname: He
authors.forename: Anding
authors.initials: A
authors.lastname: Zhang
authors.forename: Meilin
authors.initials: M
authors.lastname: Jin
mesh_terms: D000818:Animals; D001483:Base Sequence; D002681:China; D017931:DNA Primers / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing / Q000662:veterinary; D016133:Polymerase Chain Reaction / Q000662:veterinary; D017422:Sequence Analysis, DNA / Q000662:veterinary; D012703:Serotyping / Q000379:methods / Q000662:veterinary; D013290:Streptococcal Infections / Q000662:veterinary*; D017011:Streptococcus suis / Q000145:classification / Q000235:genetics*; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*
chemical_list: D017931:DNA Primers