ISSN: 0973-7510

E-ISSN: 2581-690X

Research Article | Open Access
Rudra Mishra and Pasupathi Rathinasabapathi
Department of Genetic Engineering, SRM Institute of Science and Technology, Kattankulathur -603203, Tamil Nadu, India.
J Pure Appl Microbiol. 2020;14(4):2669-2676 | Article Number: 6705 | © The Author(s). 2020
Received: 14/10/2020 | Accepted: 26/11/2020 | Published: 02/12/2020

Staphylococcus aureus exhibits resistance to most of the commonly used antibiotics. Although antibiotics suceptibility studies have been performed on the pathogen isolated from the patient samples, only limited information is available about that of S. aureus isolated from asymptomatic individuals. In this study, S. aureus was isolated from the skin microbiota of the asymptomatic individuals, and  susceptibility of the pathogen against different antibiotics and plant flavonoids was compared to drug-sensitive strain. The minimum inhibitory concentration (MIC) value  and IC50 of the pathogen were calculated against the antibiotics and flavonoids. The susceptibility pattern of the isolated strain showed higher resistance against erythromycin (100 μg mL-1) and vancomycin (25 μg mL-1). Based on the fractional inhibitory concentration index (FICI) values, the combinatory effects of antibiotics and flavonoids were categorized into synergistic, additive, and indifferent. The combination of rutin and erythromycin showed a synergistic effect with the concentrations of 31.25 μg mL-1 and 1.562 μg mL-1 against drug-sensitive strains of S. aureus. Similarly, the same combination showed synergistic effects against isolated strains at the concentration of 625 μg mL-1 and 12.5 μg mL-1.We observed an increase in drug resistance in the isolated strain of S. aureus in comparison to the drug-sensitive strain. To the best of our knowledge, this was the first study reporting increase in antimicrobial resistance of S. aureus present on asymptomatic individuals than the sensitive strain.


Asymptomatic, S. aureus, Synergistic effects

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