Relationship between virulence factor genes in coagulase-negative Staphylococcus spp. and failure of antimicrobial treatment of subclinical mastitis in sheep

Abstract

Coagulase-negative Staphylococcus spp. (CNS) are the main microorganisms involved in ovine mastitis. Treatment at the end of lactation can contribute towards cure and prevention of subclinical cases during the subsequent lactation. However, virulence factors and resistance mechanisms presented by CNS can decrease cure rates. The aims of the study were to identify the species of CNS in milk of mastitic ewes with and without antimicrobial treatment, and to investigate the presence of genes relating to resistance of β-lactam antimicrobials, formation of biofilms, production of enterotoxins and production of the toxic shock syndrome toxin. Cases of failure in the treatment were related with the presence/absence of the respective genes. Sixty sheep were divided into three groups: G1, without treatment; G2, animals treated via the intramammary route with 100mg of cloxacillin during drying off; and G3, sheep treated via the intramammary route with 50 mg of nanoparticulate cloxacillin. Milk samples were gathered during drying off and 15 and 30 days after the parturition of the subsequent lactation. The analyses to identify the species of CNS were carried out by means of the internal transcribe spacer technique and the investigation of the genes responsible for the virulence factors and resistance to oxacillin was performed using the polymerase chain reaction (PCR) technique. No sample was positive for the mecA gene. The only gene relating to production of enterotoxins was sec. Among the genes relating to production of biofilm, icaD was the only one identified in the three experimental groups. Staphylococcus warneri was the main species of CNS isolated during the pre and post-partum periods of the sheep. The species carrying genes relating to production of enterotoxins and biofilms were present in uncured sheep.

Occurrence of Methicillin-Resistant Staphylococcus spp. on Brazilian Dairy Farms that Produce Unpasteurized Cheese

“…Also, coagulase-negative Staphylococcus spp. of subclinical mastitis in sheep also showed only the sec gene related to the production of enterotoxins [26].…”

Coagulase-Negative Staphylococci as an Etiologic Agent of Ovine Mastitis, with a Focus on Subclinical Forms

“…Intramammary infections in Santa Ines ewes were investigated in several studies [9][10][11][12][13][14][15][16][17][18][19][20][21]. Both Santa Ines and Morada Nova breed ewes were researched in four other articles [22][23][24][25], while Santa Ines and Bergamacia were researched in one [26]. Samples were received from farms located in various regions, such as Sao Paolo, Pernambuco, Bauru, Para, Montes Claros, Sergipe State, and Parana State.…”

“…Toxin genes were rarely identified in the majority of the studies, and in only four articles were relatively higher percentages of positive isolates observed [21,25,26,106]. Three of them originated from Brazil.…”

“…Various molecular assays were carried out occasionally, such as Pulse Field Gel Electrophoresis (PFGE) [45,46,60,62,76], PCR-RFLP [28,60,61,65,66,95], etc. PCR for the detection of ARGs and biofilm-related genes was accomplished in 19 [21,26,27,[39][40][41]52,56,59,62,63,65,87,103,[105][106][107]138,143] and 10 studies [25][26][27]39,55,64,65,67,103,138], respectively, while in 9 cases, genes associated with the production of enterotoxins were investigated [21,25,26,63,64,67,77,106,…”

Avaliação Da Prevalência De Mastite Subclínica Em Ovelhas

“…A mastite subclínica é uma forma da doença que está intimamente relacionada com a forma mais severa da doença, a mastite clínica. Isso ocorre pois, sabe-se que existe uma grande ocorrência de evolução da enfermidade (ZAFALON et al, 2018a). O objetivo desse estudo foi estabelecer a prevalência de mastite clínica e subclínica em ovelhas, na região metropolitana de Umuarama-PR.…”