Carriage of Enterotoxin Genes by Methicillin-Resistant Staphylococcus aureus and Anti-Staphylococcal Activity of Local Citrus Fruits

Abstract

Background: Staphylococcus aureus (S.  aureus) is one of the leading causes of skin infections and food poisoning worldwide. Citrus fruits enriched with phytochemicals can exhibit anti-staphylococcal activity.

Objective: The study aims to investigate in vitro susceptibility of citrus fruits against S.  aureus harboured enterotoxin genes among food handlers, personnel, and the environment.

Methods: S. aureus was isolated from food handlers, personnel, and the environment. Methicillin-Resistant Staphylococcus aureus (MRSA) screening was performed using cefoxitin antibiotic discs. The antimicrobial activity of citrus fruits, including Citrus limon (Lemon), Citrus pseudolimon (galgal), Citrus tangerine (fruiter), Citrus sinensis (malta), and Citrus paradisi (grapefruit), was analyzed by performing well-diffusion assay and broth microdilution method. Genes for toxins production, sea and seg were detected using a Polymerase Chain Reaction (PCR).

Results: Out of 200 swab samples, 50 (25%) S. aureus were isolated using the biochemical battery. Antibiotic susceptibility testing (AST) and cefoxitin disc revealed 12 (24%) MRSA strains. Most strains were sensitive to Citrus limon, followed by Citrus pseudolimon, Citrus tangerine, Citrus sinensis, and Citrus paradisi. PCR results detected carriage of the sea gene in 4 (8%) isolates, and 20 (40%) isolates harboured the seg gene.

Conclusion: The prevalence of S. aureus, mainly MRSA, was high in the environment. These resistant strains' carriage of sea and sea enterotoxin genes increases their virulence and leads to untreatable infections. The antibacterial activities of citrus fruits should be explored using adavance methods.