Antimicrobial and modulating activity of essential oils against bacteria isolated from goat dairy products in northeastern Brazil

Abstract

In recent years, novel strategies to combat (multi-) drug-resistant microorganisms have been investigated. Essential oils (EOs) with bactericidal, bacteriostatic, and fungicidal activity have been used to treat infections and in food sanitation. This study aimed to determine the antimicrobial and modulating activity of Cinnamomum cassia (cinnamon) and Eugenia caryophyllus (clove) essential oils against microorganisms isolated from goat milk processing plants in northeastern Brazil, and their synergistic effect when combined with antimicrobial agents. The microdilution technique was used to obtain the minimum inhibitory (MIC) and bactericidal concentrations (MBC) and the antibiotics studied were ampicillin, amoxicillin/clavulanic acid, cephalothin, ceftazidime, chloramphenicol, gentamicin, meropenem, norfloxacin, sulfamethoxazole/trimethoprim, and tetracycline. Klebsiella pneumoniae (MIC50) and Escherichia coli (MIC90) were sensitive to cinnamon EO. Clove EO did not inhibit the growth of either microorganism. In regard to MBC, cinnamon EO had a bactericidal effect against six K. pneumoniae and six E. coli samples. For the antibiotics evaluated, a greater synergistic effect was observed for cinnamon EO associated with gentamicin and meropenem, and antagonistic effect with ampicillin, sulfamethoxazole/trimethoprim, and tetracycline. As such, EOs may be an alternative for the control of pathogenic microorganisms.

Keywords

• Dairy products
• Microbiology
• Phytotherapy
• Synergism.