Anti-bacterial activity of essential oils against multidrug-resistant foodborne pathogens isolated from raw milk

Abstract

The presence of pathogenic bacteria in food is considered as a primary cause of food-borne illness and food quality deterioration worldwide. The present study aimed to determine the effectiveness of five essential oils (EOs) against multidrug-resistant foodborne pathogens. In the current study Gram-negative bacteria (Escherichia, Enterobacter, Citrobacter, Proteus, Pseudomonas, and Klebsiella) and the Gram-positive bacteria Staphylococcus were isolated from raw milk and biochemically characterized. The anti-bacterial effect of different antibiotics and EOs (thyme, oregano, lemongrass, mint, and rosemary) was determined using the standard disc diffusion method. The antibiogram study revealed that Gram-negative bacteria were highly resistant to penicillin while Staphylococcus was resistant to streptomycin, amoxicillin, and lincomycin. Moderate resistance was observed to doxycycline, amikacin, enrofloxacin, kanamycin and cefixime. Isolates were found less resistant to gentamycin, chloramphenicol, and ciprofloxacin. EOs showed a broad range of antimicrobial activity against all bacteria except P. aeruginosa. Of these, thyme was more effective against most of the multi-drug resistant bacterial strains and formed the largest zone of inhibition (26 mm) against Escherichia followed by oregano oil (18 mm) against Staphylococcus (p<0.05). Klebsiella spp and Citrobacter spp showed resistance to mint and lemongrass oil respectively. The EOs such as lemongrass, mint and rosemary were less active against all the bacteria. The findings of the recent study suggest the use of EOs as natural antibacterial agents for food preservation.

Liquid chromatography–tandem mass spectrometry profile and antioxidant, antimicrobial, antiproliferative, and enzyme activities of Thymus pectinatus and Thymus convolutus: in vitro and in silico approach

“…[12][13][14][15] Thymus essential oils have been associated with various biological activities, most of which are related to the thymol and carvacrol content. [16][17][18][19][20] In addition, the phenolic acids (vanillic acid, gallic acid), 21,22 flavonoids (kaempferol, apigenin, apigenin 7-O-glucoside, luteolin, eriodictyol, chrysoeriol, naringenin, hesperetin), [22][23][24] steroids (carnasol, ursolic, oleanolic acid, sitosterol), 22 and phenylpropanoids (rosmarinic acid, caffeic acid, cinnamic acid, ferulic acid) 21,22,25 compounds attributed to the wide spectrum of biological activities were identified as the phytochemical composition of Thymus extracts. Previous studies antioxidant, antidiabetic, 26 enzyme inhibitory, 26 wound healing, 22 antiproliferative, 27 anticancer, 27 antispasmodic, 27 anthelmintic, 27 cytotoxic 28 and anti-inflammatory 29 activities of Thymus species were reported.…”

“…The essential oils of these plants are rich in thymol, carvacrol, p ‐cymene, and γ ‐terpinene 12‐15 . Thymus essential oils have been associated with various biological activities, most of which are related to the thymol and carvacrol content 16‐20 . In addition, the phenolic acids (vanillic acid, gallic acid), 21,22 flavonoids (kaempferol, apigenin, apigenin 7‐ O ‐glucoside, luteolin, eriodictyol, chrysoeriol, naringenin, hesperetin), 22‐24 steroids (carnasol, ursolic, oleanolic acid, sitosterol), 22 and phenylpropanoids (rosmarinic acid, caffeic acid, cinnamic acid, ferulic acid) 21,22,25 compounds attributed to the wide spectrum of biological activities were identified as the phytochemical composition of Thymus extracts.…”