Avaliação in vitro da atividade antimicrobiana do óleo essencial de Ocimum gratissimum em associação com antibióticos

Abstract

The combination of essential oils (EO) with antibacterial substances has shown significant efficacy for inhibiting the growth of microorganisms. In this research, we evaluated the inhibitory action of EO obtained from fresh leaves of Ocimum gratissimum (O. gratissimum) in association with antimicrobial susceptibility testing disks against Staphylococcus aureus and Pseudomonas aeruginosa, using the agar diffusion method described by Oliveira et al (2006). We evaluated the following antibiotics: ampicillin, amoxicillin clavulanic acid; penicillin G; oxacillin; cephalothin; cefoxitin; ceftazidime; cefuroxime; cefepime; erythromycin; ciprofloxacin; vancomycin; tetracycline; chloramphenicol; clindamycin; amikacin; gentamicin; rifampin; sulfazotrim; meropenem. The obtained results showed synergistic activity of microbial growth inhibition of the EO associated with rifampin, ciprofloxacin and tetracycline against S. aureus; and, cefepime and ciprofloxacin against P. aeruginosa in these concentrations in discs. Through Checkerboard technique it was quantified the reduction of the Minimum Inhibitory Concentration (MIC) of ciprofloxacin and tetracycline associated with the O. gratissimum. Ciprofloxacin associated with the MIC of EO of O. gratissimum decreased the MIC from 0.6 μg/mL to 0.076 μg/mL against S. aureus and 0.03 μg/mL to 0.00119 μg/mL against P. aeruginosa. While tetracycline in combination decreased the MIC from 0.028 μg/mL to 0.0018 μg/mL for S. aureus and from 4 μg/mL to 0.93 μg/mL against P. aeruginosa . Thus, the EO of O. gratissimum demonstrated increased antibacterial activity of the evaluated antibiotics. However, it is noteworthy that the study was conducted by in vitro test methods, requiring confirmation of results from experimental models in vivo, enabling the ratification of the results with greater reliability.