ABSTRACT
Antimicrobial resistance (AMR) in Mycoplasma bovis has been previously associated with topoisomerase and ribosomal gene mutations rather than specific resistance-conferring genes. Using whole genome sequencing (WGS) to identify potential new AMR mechanisms for M. bovis, it was found that a 2019 clinical isolate with high MIC (2019-043682) for fluoroquinolones, macrolides, lincosamides, pleuromutilins and tetracyclines had a new core genome multilocus sequencing (cgMLST) type (ST10-like) and 91% sequence similarity to the published genome of M. bovis PG45. Closely related to PG45, a 1982 isolate (1982-M6152) shared the same cgMLST type (ST17), 97.2% sequence similarity and low MIC results. Known and potential AMR- associated genetic events were identified through multiple sequence alignment of the three genomes. Isolate 2019-043682 had 507 genes with non-synonymous mutations (NSMs) and 67 genes disrupted. Isolate 1982-M6152 had 81 NSMs and 20 disruptions. Using functional roles and known mechanisms of antimicrobials, a 55 gene subset was assessed for AMR potential. Seventeen were previously identified from other bacteria as sites of AMR mutation, 38 shared similar functions to them, and 11 contained gene-disrupting mutations. This study indicated that M. bovis may obtain high AMR characteristics by mutating or disrupting other functional genes, in addition to topoisomerases and ribosomal genes.
ABSTRACT
Mycoplasma hyopneumoniae causes highly contagious swine enzootic pneumonia worldwide. It has been reported that highly diversified M. hyopneumoniae strains exist in different parts of the world. We found p146 gene sequencing analysis, an affordable and simple-to-perform typing method, to be specific and highly sensitive when applied to the molecular typing of 113 M. hyopneumoniae-positive clinical samples directly without culture. The samples were submitted to the Animal Health Laboratory at the University of Guelph (Ontario, Canada) during 2009-2017 from 40 different geographic areas in Ontario. Using a previously described criterion of grouping strains with < 4-bp differences into the same molecular type (p146 type), the 113 clinical samples clustered into 19 p146 genotypes. Dominant types were found in 2016 and 2017 only, indicating that highly diversified M. hyopneumoniae strains existed in Ontario. Some strains from the same geographic location but different years had the same sequence types, indicating that the same strain types circulate persistently in the field. Different p146 genotypes were also identified from similar geographic locations, indicating that either M. hyopneumoniae strains are prone to mutation or that multiple strains can infect the same or nearby swine production units.
