Fresh fruit surface: A potential source for multidrug-resistant biofilm-forming Enterococcus faecalis having potential public health significance.

Abstract

Fruits are important in the diet because of the nutrients, vitamins, and minerals they provide for a healthy life; however, they can also serve as a potential source of opportunistic pathogens, including enterococci. They are considered zoonotic pathogens that cause severe infections in humans. This work aimed to isolate Enterococcus faecalis from fruit surfaces and to detect its virulence genes, biofilm-forming ability, and antibiotic resistance patterns. A total of 76 samples of seven different types of fruits were collected and surface-washed, and used to isolate and identify E. faecalis by cultural and biochemical tests, followed by polymerase chain reaction (PCR), the disk diffusion method for antimicrobial susceptibility testing, a Congo Red Agar test for the determination of biofilm-forming ability, and PCR for virulence gene detection. Out of 76 samples, 47 (61.84%) fruit samples were found to be positive for E. faecalis, with the highest prevalence in oranges compared to the other six fruits. In the phenotypic antibiogram study, resistance was most frequently observed against commonly used antibiotics, including ampicillin (90.00%) and erythromycin (57.50%), while notable resistance was also detected against vancomycin (47.50%) and the last-resort antibiotic linezolid (47.50%). The ampicillin-resistance gene, blaTEM, was present in 65% of the isolates. Additionally, 60% of isolates exhibited multidrug resistance (MDR), with the MAR index ranging from 0.33 to 0.78. Key virulence genes (agg, ace, gelE, fsrB, and pil) and biofilm-forming capabilities were distributed among the isolates, indicating their potential for persistence and pathogenicity. These findings suggest that fruit surfaces harbor antibiotic-resistant E. faecalis; therefore, fruits should be thoroughly washed before eating and monitored using One Health strategies to reduce the risk to human health.