Evaluation of Mollicutes microorganisms in respiratory disease of cattle and their relationship to clinical signs

• Grant number: 17/05911-2
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: June 01, 2017
• End date: November 30, 2017
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Clinics and Surgery
• Principal Investigator: Lilian Gregory
• Grantee: Lilian Gregory
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Background Bovine respiratory disease (BRD) is an important disease in cattle production that remains responsible for economic losses in dairy and feedlot herds. Mycoplasma spp. is described as important etiological agents of BRD. Objectives The aim of this study was to evaluate the occurrence of the most important mycoplasmas in the lower respiratory tract of healthy and BRD cattle in relation to clinical signs of BRD. Methods Sixty young dairy cattle were classified as healthy (n=32) and BRD cattle (n= 28). Tracheal lavage samples were collected and added to tubes containing Hayflick media. Mycoplasma spp. was identified by the presence of fried-egg like colonies, biochemical tests and polymerase chain reaction. Occurrence of Mollicutes, M. bovis, M. mycoides subsp. mycoides SC and M. dispar was analyzed. The association between clinical signs of BRD and the presence of Mycoplasma spp. was also evaluated.Results Colonies were obtained from a one-year-old BRD calf only. However, the species identification was not possible. Mollicutes (P = 0.035) and M. dispar (P = 0.036) were increased in BRD cattle. A tendency was observed between Mollicutes and crackle (P = 0.057). M. dispar was associated to tachypnea (P = 0.045) and mixed dyspnea (P = 0.003). In addition, a tendency was observed in relation to heart rate (P = 0.062) and crackle (P = 0.062).Conclusions and clinical importanceThe results confirmed the importance of mycoplasmas as etiologic agent of BRD, and suggested M. dispar as part of respiratory microbiota and its possible role in the development of BRD. (AU)