Aspectos das condições higiênico-sanitárias em unidades leiteiras em municípios do Rio de Janeiro e utilização de ferramentas moleculares para caracterização dos principais agentes bacterianos envolvidos na etiologia das mastites

Abstract

The dairy agribusiness has great social significance as it is practiced in a nation wide scale. A major cause of economic losses in this sector is the inflammation of the mammary gland, which can be caused by various microorganisms. These pathogens can produce virulence factors that allow colonization, infection and evasion from immune cells. On the other hand, resistance factors allow bacterial cells to neutralize the effects of antibiotics, making them difficult to eliminate. The introduction of appropriate hygiene practices in the dairy herd management is the most efficient way to control mastitis. Thus, it is important to know the conditions of different properties, to identify the bacterial diversity involved in the etiology of mastitis and to establish their resistance and virulence profiles. This will allow the gain in epidemiological knowledge to assist the monitoring of critical control points within the milking environment. This study performed an epidemiological investigation in eight dairy farms, located in the Southern Fluminense Region of Rio de Janeiro State. Through the use of a diagnostic instrument, it was detected that 87.5% of the properties had unsatisfactory hygiene conditions in the milking line and in the water supply, which were below potability parameters. In total, 389 isolates were obtained from milk samples, 90% (350/389) of them belonged to the Staphylococcusspp. genus, and10% were identified as Gram-negative (39/389) rods. From the milking line samples 101 isolates were obtained, of which 80.2% (81/101) were identified as Staphylococcus spp. and 19.8% (20/101) were classified as Gram-negative rods. The icaAandicaD genes were detected in 15.2% (38/250) and 21.6% (54/250) of isolates from milk samples, and also in 11% (11/100) and 20% (20/100) of isolates from the milking line, respectively. The percentage of oxacillin resistance, in Staphylococcus spp. isolates was of 39.14% (137/350) and 83.16% (84/101), considering milk and milking line samples, respectively. Among the isolates from the milking line, 23% were positive for the mecA gene. Evaluation of genetic diversity by the PFGE technique evidenced that Staphylococcus spp. strains from milk samples showed higher genetic distance when compared to strains isolated from the milking line. These results show that the constant monitoring of pathogens in the environment of dairy production in the region is essential for the development of new control measures of bovine mastitis.