title: Whole Genome Sequence Analysis of Pig Respiratory Bacterial Pathogens with Elevated Minimum Inhibitory Concentrations for Macrolides.
abstract: Macrolides are often used to treat and control bacterial pathogens causing respiratory disease in pigs. This study analyzed the whole genome sequences of one clinical isolate of Actinobacillus pleuropneumoniae, Haemophilus parasuis, Pasteurella multocida, and Bordetella bronchiseptica, all isolated from Australian pigs to identify the mechanism underlying the elevated minimum inhibitory concentrations (MICs) for erythromycin, tilmicosin, or tulathromycin. The H. parasuis assembled genome had a nucleotide transition at position 2059 (A to G) in the six copies of the 23S rRNA gene. This mutation has previously been associated with macrolide resistance but this is the first reported mechanism associated with elevated macrolide MICs in H. parasuis. There was no known macrolide resistance mechanism identified in the other three bacterial genomes. However, strA and sul2, aminoglycoside and sulfonamide resistance genes, respectively, were detected in one contiguous sequence (contig 1) of A. pleuropneumoniae assembled genome. This contig was identical to plasmids previously identified in Pasteurellaceae. This study has provided one possible explanation of elevated MICs to macrolides in H. parasuis. Further studies are necessary to clarify the mechanism causing the unexplained macrolide resistance in other Australian pig respiratory pathogens including the role of efflux systems, which were detected in all analyzed genomes.
authors.affiliation: 1 School of Veterinary Science, The University of Queensland , Gatton, Queensland, Australia .
authors.forename: Denise Ann Estarez
authors.initials: DA
authors.lastname: Dayao
authors.affiliation: 1 School of Veterinary Science, The University of Queensland , Gatton, Queensland, Australia .
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Seddon
authors.affiliation: 1 School of Veterinary Science, The University of Queensland , Gatton, Queensland, Australia .
authors.forename: Justine S
authors.initials: JS
authors.lastname: Gibson
authors.affiliation: 2 Queensland Alliance for Agriculture and Food Innovation, EcoSciences Precinct, The University of Queensland , Dutton Park, Queensland, Australia .
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Blackall
authors.affiliation: 2 Queensland Alliance for Agriculture and Food Innovation, EcoSciences Precinct, The University of Queensland , Dutton Park, Queensland, Australia .
authors.forename: Conny
authors.initials: C
authors.lastname: Turni
mesh_terms: D016977:Actinobacillus pleuropneumoniae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001315:Australia / Q000453:epidemiology; D001483:Base Sequence; D016950:Bordetella bronchiseptica / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D018628:Gene Dosage; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D044137:Haemophilus parasuis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D059014:High-Throughput Nucleotide Sequencing; D018942:Macrolides / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D016979:Pasteurella multocida / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D012141:Respiratory Tract Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D013552:Swine; D013553:Swine Diseases / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides; D012338:RNA, Ribosomal, 23S
keywords: 23S rRNA; Haemophilus parasuis; WGS analysis; macrolide resistance; mutation