Resistance profile and biofilm production capacity of Staphylococcus spp. beef slaughterhouse isolates and their sensitivity to Rosmarinus officinalis essential oil

Microorganisms can interfere with meat quality, being a public health problem. The aim of this study was to characterize the antimicrobial susceptibility profile of Staphylococcus spp. isolated from utensils of a bovine slaughterhouse and to evaluate the antibacterial and antibiofilm activity of the essential oil of Rosmarinus officinalis L. (rosemary). Samples of surfaces and utensils used during slaughter in the northwest of the state of Paraná, Brazil were collected. After isolation and differentiation of the isolates by the coagulase test, the antimicrobial susceptibility test, Staphylococcus aureus identification and mecA gene research were performed. The study for biofilm production was carried out by the method of adhesion in borosilicate tube and by adhesion in polystyrene plate. Subsequently, the inhibitory activity of the R. officinalis essential oil and its ability to inhibit biofilm were investigated. Twenty-two of the samples collected were identified as coagulase-negative Staphylococcus and five as coagulase-positive Staphylococcus. There was resistance to all antibiotics tested, with clindamycin (33.33%) and rifampicin (29.6%) showing the highest rate. None of the samples was confirmed as Staphylococcus aureus or for the presence of the mecA resistance gene. The essential oil inhibited the growth of 48% of the isolates at a concentration of 16,000 µg/mL. Of these isolates, 33% were positive for biofilm production and this biofilm was also inhibited by the essential oil. This work revealed that multidrug-resistant Staphylococcus and biofilm producers are present in the slaughter environment and are susceptible to the essential oil of R. officinalis.