Comparative genomic analysis of Brazilian Mesomycoplasma ovipneumoniae strains revealed genomic differences associated with the geographic origin and health status and mutations in the gyrA.

Sheep respiratory disease (SRD) is a multifactorial illness commonly affecting sheep. Mesomycoplasma (Mycoplasma) ovipneumoniae is one of the most important etiological agents of SRD and should be better understood, especially in countries where it was recently detected, such as Brazil. Also, the intensive use of quinolones in mycoplasmal infections increases the selective pressure for resistance to this drug class, and no data about antimicrobial resistance in Brazil is available. Therefore, this study aimed to perform a comparative genomic analysis of newly isolated Brazilian M. ovipneumoniae strains, identify point mutations in target genes that may be associated with antibiotic resistance, and perform a phylogenomic analysis of these strains with available genome representatives of M. ovipneumoniae. Glucose-fermenting fried egg-like colonies identified as M. ovipneumoniae were obtained after a culture of tracheobronchial lavage from infected sheep. The genomes were sequenced, de novo assembled and comparatively evaluated. Important putative virulence factors were detected in all isolates: the analysis of the average nucleotide homology of all these genes with the M. ovipneumoniae ATCC 29419 revealed associations between clpB, lgt, tuf, and dnaJ genes and geographic location. In addition, nucleotide substitutions in a few positions of the Quinolone-Resistant Determinant Region of the gyrA gene, including the Ser83Ala, were detected. The phylogenomic analysis showed that the Brazilian isolates belonged to two different clades corresponding to geographic location, and the isolates from São Paulo showed high similarity, which differs from isolates from Rio de Janeiro. This first genomic analysis of the Brazilian M. ovipneumoniae genomes demonstrates strain segregation according to location and health status, reinforcing the importance of continuous surveillance and diagnostics of this bacteria causing sheep respiratory disease in the Brazilian flocks.

Evaluation of Mollicutes Microorganisms in Respiratory Disease of Cattle and Their Relationship to Clinical Signs.

BACKGROUND: Bovine respiratory disease (BRD) is an important problem in cattle production that is responsible for economic losses in dairy herds. Mycoplasma spp. are described as an important etiological agent of BRD. HYPOTHESIS: To evaluate the occurrence of the most important mycoplasmas in the lower respiratory tract of healthy and BRD cattle in relationship to clinical signs of BRD. ANIMALS: Sixty young dairy cattle were classified as healthy (n = 32) or cattle showing clinical signs of BRD (n = 28). METHODS: Tracheal lavage samples were collected and added to tubes containing Hayflick media. Mycoplasma spp. were identified by the presence of "fried egg" like colonies, biochemical tests and polymerase chain reaction (PCR). Occurrence of Mollicutes, M. bovis, M. mycoides subsp. mycoides SC and M. dispar was evaluated. The association between clinical signs of BRD and the presence of Mycoplasma spp. also was evaluated. RESULTS: Colonies were obtained from a 1-year-old BRD calf only. However, species identification was not possible. Mollicutes (P = .035) and M. dispar (P = .036) were more common in BRD cattle. The relationship between Mollicutes and crackle (P = .057) was not significant. M. dispar was associated to tachypnea (P = .045) and mixed dyspnea (P = .003). Relationships to heart rate (P = .062) and crackle (P = .062) were not significant. CONCLUSIONS AND CLINICAL IMPORTANCE: The results confirmed the importance of mycoplasma as an etiologic agent of BRD and suggested M. dispar as part of the respiratory microbiota and its possible role in the development of BRD.