CHARACTERIZATION OF STAPHYLOCOCCUS AUREUS PHENOTYPES SLIME PRODUCERS AND BIOFILM FORMATION IN ISOLATES OBTAINED FROM DAIRY COWS WITH SUBCLINICAL MASTITIS

Abstract

Background. Staphylococcus aureus is considered the main causal agent of mastitis in dairy herds globally, affecting milk production and constituting a potential risk to public health. The presence of virulence factors such as biofilm formation and slime production favor colonization and persistence of the mammary gland infections. Objective. The study aims to characterize the phenotypes of slime-producing and biofilm-forming S. aureus associated with subclinical mastitis with different CMT (California Mastitis Test) degrees and their relationship with the persistence of infection. Methodology. To characterize the slime-producing and biofilm-forming S. aureus phenotypes, 116 individual milk samples were taken from cows with subclinical mastitis through the CMT, obtaining 80 S. aureus isolates. Slime production on Congo Red agar was determined in vitro, and the conformation of bacterial clusters adherent identified biofilm formation to rigid surfaces and crystal violet staining. Results. 68.8% (55) of the isolates produced slime, of which 20% (16) were considered as producers and 48.8% (39) as intermediate producers. 82.5% (66) of the total isolates were related to the formation of biofilm in different degrees; 1.25% (1) very high trainer, 41.25% (33) high trainer, and 40.0% (32) moderately trainer. Highly biofilm-forming isolates were associated with subclinical mastitis degrees 2 and 3 of the CMT. Implications. The verification of slime and biofilm formation in most of S. aureus isolations obtained from subclinical mastitis may imply that their presence is related to the condition's persistence and severity. Conclusion. The association between the phenotypes of slime-producing and biofilm-forming S. aureus was established with high degrees of the CMT and mammary infection persistence in the cows studied.