A cross-sectional study of 76 fruit samples collected from seven market locations around Mymensingh, Bangladesh, detected Enterococcus faecalis on fruit surfaces by culture and PCR. Overall, 47 of 76 samples (61.84%) were PCR-positive for E. faecalis. By location, Sesh more and Kewatkhali had the highest positivity (75% each); the authors reported a statistically significant difference in prevalence among sampling sites (p = 0.036). By fruit type, oranges had the highest PCR positivity (70%), followed by apple (66.67%), mango (62.5%), malta (60%), guava (60%), grapes (56.25%), and dates (50%). The difference across fruit types was not statistically significant (p = 0.988).
Between May and September 2024, investigators collected 76 fruit samples comprising apples (n = 18), oranges (n = 10), maltas (n = 15), grapes (n = 16), mangoes (n = 8), guavas (n = 5), and dates (n = 4). Each fruit was surface-washed with PBS; aliquots of the wash were enriched in nutrient broth and incubated at 37 °C. Primary isolation used Enterococcus Agar Base, and colonies were screened by Gram stain and biochemical tests. Molecular confirmation targeted the ddl E. faecalis gene by simplex PCR using extracted genomic DNA obtained by boiling and chilling the enriched culture.
Antibiotic susceptibility was assessed by disk diffusion following Clinical and Laboratory Standards Institute (2024) guidelines using nine antibiotics representing WHO Access, Watch, and Reserve groups. A subset of isolates was tested for biofilm production phenotypically on Congo Red Agar (CRA). Virulence-associated genes (agg, ace, gelE, fsrB, pil) and the ampicillin-resistance gene blaTEM were detected by simplex PCR.
Eighteen randomly chosen PCR-positive isolates were evaluated on Congo Red Agar to determine biofilm-forming phenotype. Among these, 38.9% (7/18) were classified as strong biofilm formers, 33.3% (6/18) as intermediate, and 27.8% (5/18) as non-biofilm producers. The study reported no statistically significant variation in the frequency distribution of biofilm-forming categories across the tested isolates.
Twelve randomly selected E. faecalis isolates underwent PCR screening for five virulence genes. Detection rates were: agg in 91.67% (11/12), pil and gelE each in 83.33% (10/12), fsrB in 75% (9/12), and ace in 50% (6/12). Bivariate analysis identified a strong positive correlation between gelE and fsrB (Spearman ρ = 0.775; p < 0.01) and a significant correlation between fsrB and ace (ρ = 0.577; p < 0.05). The authors noted that isolates classified as strong biofilm formers more often harbored agg and pil genes, while intermediate formers displayed varying combinations of agg, pil, fsrB, gelE, and ace.
Antibiogram testing of 40 isolates revealed high levels of phenotypic resistance across multiple antibiotic classes. Within the WHO Access group, 90% of isolates were resistant to ampicillin, 57.5% to erythromycin, and 15% to tetracycline. In the Watch group, resistance was observed to rifampin in 70% of isolates, vancomycin in 47.5%, levofloxacin in 7.5%, and ciprofloxacin in 5%. From the Reserve category, 47.5% of isolates were resistant to linezolid. The blaTEM gene was detected in 65% of ampicillin-resistant isolates (13/20) by PCR.
The study reported that 60% of isolates exhibited multidrug resistance (MDR), defined as resistance to at least three antimicrobial groups. Multiple antibiotic resistance (MAR) indices among isolates ranged from 0.33 to 0.78, indicating exposure to multiple antibiotics or antibiotic-rich environments. The combination of virulence determinants, biofilm-forming ability, and resistance to critical agents including vancomycin and linezolid suggests that fruit surfaces can act as reservoirs for clinically relevant, hard-to-treat E. faecalis. The authors recommended thorough washing of fruits before consumption and advocated for One Health monitoring strategies to reduce transmission risk.
The source article provides comprehensive methods and many results but the provided text truncates mid-sentence in the results relating to bivariate statistical analyses of antibiotic resistance. Specific details about which antibiotic resistances correlated with which virulence genes or biofilm phenotypes beyond the reported correlations among virulence genes were not reported in the available source excerpt. No additional demographic or temporal trends beyond the stated sampling frame and locations were provided in the supplied text.
Overall, the study documents a high occurrence of Enterococcus faecalis on fresh fruit surfaces in the sampled area, frequent carriage of virulence genes, considerable biofilm-forming potential among isolates tested, and substantial multidrug resistance, including resistance to last-resort antibiotics. These findings support the authors' public health recommendations for fruit hygiene and surveillance.