Ação antimicrobiana in vitro de Psidium guajava L. contra Staphylococcus aureus isolados de leite mastítico

Abstract

Mastitis is a disease that affects dairy cattle, an intramammary infection. Staphylococcus aureus are the major mastitis causing bacteria and the milk can be contaminated by the contact with infected teats. For treatment, due to the indiscriminate use of antimicrobials drugs commercialized, the appearing of multi-resistant strains is notorious. An alternative to the antimicrobial resistance problem is the use of plant extracts like Psidium guajava L. The objective of this study was to evaluate, in vitro, the microbial sensibility profile of Staphylococcus aureus isolated from milk samples of cows infected with mastitis, against antimicrobial agents and hydroalcoholic leaf of Psidium guajava L. Plants were harvested in three rural properties located in the municipality of Alfenas/MG region. Sampling animals was not probabilistic. Milk samples were cultured for presence of Staphylococcus sp. Additionally, the isolated bacteria were identified as Staphylococcus aureus and subjected to many tests to check the antimicrobial sensibility. The hydroalcoholic extract of Psidium guajava L. was prepared and antimicrobial tests were performed by the technician in wells. Contamination by Staphylococcus aureus was confirmed in 55% of the analyzed samples. The most effective antibiotics were clindamycin, erythromycin and rifampin. Penicillin G was the antimicrobial that showed the lower levels of sensibility. The hydroalcoholic extract of the leaf of Psidium guajava L. showed antimicrobial activity against all strains of isolated Staphylococcus aureus by inhibiting microbial growth in all tested concentrations. Therefore the use of this plant extract can be an alternative method to combat the increase incidence of microorganisms resistant to antimicrobial drugs sold, besides a potential field of study.