title: Antimicrobial susceptibility and plasmid analysis of Actinobacillus pleuropneumoniae isolated in Taiwan.
abstract: Sixty Actinobacillus pleuropneumoniae (App) strains from pigs in Taiwan were examined. Serotyping revealed that these belonged to serovars 1 (n=53), 2 (n=3), and 5 (n=4). Agar disk diffusion susceptibility testing of the isolates showed 55 (92%) were resistant to three or more antimicrobial agents. Six resistance patterns were observed. Ampicillin-chloramphenicol-flumequine-nalidixic acid-streptomycin-sulfonamide/trimethoprim-tetracycline was the most common multi-resistance pattern. Minimal inhibitory concentration of 14 antimicrobial agents was determined. The isolates were highly susceptible to ceftiofur and trimethoprim in vitro. Isolates were resistant to streptomycin, ampicillin, and nalidixic acid. All isolates were examined for the presence of plasmids using the alkaline lysis method. Forty three (72%) isolates had four plasmid bands with an approximate sizes of 3.5, 4.3, 5.8 and 6.0 kb; 12 (20%) had three bands at 3.5, 4.3 and 5.2 kb, and 5 (8%) had no plasmid bands. Antimicrobial resistance plasmids were detected in resistant strains of App. Three antimicrobial resistance plasmids were transformed into E. coli DH5 alpha. pTMY1 (4.3 kb) encoded a streptomycin kinase and a dihydropteroate synthase; pTMY2 (6.0 kb) encoded ROB-1 beta-lactamase and aminoglycoside 3'-phosphotransferase; pTMY3 (5.2 kb) encoded only ROB-1 beta-lactamase. The 4.3 kb plasmid was sequenced and consisted of 4242 bp with 42.9% GC content. The 4.3 kb plasmid DNA sequence was 98% homologous to a plasmid previously isolated from Pasteurella haemolytica.
authors.affiliation: Department of Veterinary Medicine, College of Agriculture, National Taiwan University, 142 Zhou-Shan Road, Taipei 106, Taiwan, ROC. cfchang@ccms.ntu.edu.tw
authors.forename: Chao Fu
authors.initials: CF
authors.lastname: Chang
authors.forename: Tung Mao
authors.initials: TM
authors.lastname: Yeh
authors.forename: Chin Cheng
authors.initials: CC
authors.lastname: Chou
authors.forename: Yung Fu
authors.initials: YF
authors.lastname: Chang
authors.forename: Tai Sheng
authors.initials: TS
authors.lastname: Chiang
mesh_terms: D000189:Actinobacillus Infections / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D016977:Actinobacillus pleuropneumoniae / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001483:Base Sequence; D004269:DNA, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D008969:Molecular Sequence Data; D010957:Plasmids; D011001:Pleuropneumonia / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D012703:Serotyping / Q000662:veterinary; D013552:Swine; D013553:Swine Diseases / Q000188:drug therapy / Q000382:microbiology*; D013624:Taiwan
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial