Atividade antimicrobiana de óleos essenciais frente a Staphylococcus aureus e Streptococcus agalactiae isolados de mastite bovina

Abstract

Treatments for mastitis based on antibiotic therapy are not always effective which may lead to selection of resistant bacteria and the presence of residues in milk. In this context the use of compounds derived from plants configures as an alternative to control mastitis in dairy cows. The objective of this study was to determine, by the method of broth micro dilution, the minimum inhibitory concentration (MIC) of essential oils of Salvia sclarea, Eugenia caryophyllata, Thymus vulgaris, Cymbopogon winterianus, Elettaria cardamomun, Cymbopogon flexuosos, Rosmarinus officinalis and Cinnamomum cassia for isolates of S. aureus and S. agalactiae associated with clinical and subclinical mastitis. For the isolates of S. aureus, was observed that the essential oil of C. cassia presented the highest efficiency with a MIC of 0,03906%, followed by the oils of T. vulgaris and C. flexuosos (0,15625%) and E.caryophyllata e C. winterianus (0,3125%). The essential oils of R. officinalis, E. cardamomun and S.sclarea showed no antimicrobial activity presenting MIC’s equal or higher to 2,5%. For isolates of S. agalactiae, the oil of C. salvia was also the most effective, presenting a MIC of 0,01953%, followed by the oils of E. caryophyllata (0,078125%), C. flexuosos and T. vulgaris (0,15625%), and C. winterianus and E. cardamomun (0,625%). The oils of S. sclarea (1,25%) and R. officinalis didn’t show significant antibacterial activity (CIM˃2,5%). Combinations were made among the essential oils of C .cassia, C. flexuosos and E. caryophyllata, observing synergism in all combinations tested, especially those involving the essential oil of C. cassia. The results indicated the prospect of using essential oils to control bovine intramammary infections caused by S.aureus and S.agalactiae.