Evaluation of Bacterial Contamination and Safety of Bangladeshi Paper Currencies (Taka) Collected from Various Food Vendors

Abstract

Aims: Paper currency notes can act as transmission vehicle for microorganisms because of their widespread use and constant exchange from hand to hand. This study aimed at determining the level of bacterial contamination and the safety of the notes collected from some food vendors in Noakhali district, Bangladesh.  Methodology: A total of 20 currency notes (BDT 2, BDT 5, BDT 10, BDT 20) were collected at random from 5 different food vendors (Chotpoti, Chicken, Jhalmuri, Fish and Meat) at Noakhali, Bangladesh. Each sample was washed with Tryptic Soy Broth (TSB) and inoculated onto Nutrient Agar (NA) for total viable count. Standard microbiological and biochemical methods were used for the enumeration, isolation and characterization of pathogenic bacteria. Antibiotic susceptibility testing of isolated bacteria against commonly used antibiotic drugs was carried out through Clinical and Laboratory Standards Institute (CLSI) guidelines. Growth potential of the isolated bacteria observed in selected weaning foods (milk and mango juice). Results: About 90% of the currency notes were contaminated with bacteria. The highest amount of viable count (3.3×1010 CFU/ml) was found in BDT 10 of Chotpoti sample. A total of 30 bacterial isolates were identified from all the currencies. Of them, Escherichia coli (33.33%) was the most frequently isolated bacterial species followed by Staphylococcus aureus (26.66%), Bacillus cereus (13.33%), Micrococcus spp. (10%), Klebsiella spp. (3.33%), Salmonella spp. (3.33%), Vibrio cholerae (10%). Antibiotic sensitivity test reveals that, most of the isolates were highly resistant to vancomycin, ampicillin and penicillin, while no or little resistance was found against gentamicin, ciprofloxacin, tetracycline and chloramphenicol. In challenge study, Salmonella spp., S. aureus reached the level of infective dose within 6 or 12 hours of inoculation in respective foods. Vibrio cholera didn’t reach this stage. The pH values of both food samples challenged with selected microorganism showed some variability because of fermentation.  Conclusion: This study revealed that paper currencies collected from food vendors in Noakhali, Bangladesh were contaminated with different pathogenic bacteria including multi drug resistant strains. Thus, it calls for awareness development on the potential risks associated with poor handling of paper currencies at all level of the food establishments.