Assessing bacteriological contamination of paper currencies of Bangladesh collected from public places of Dhaka city

Abstract

Paper currency is known to have bacteria on its surface that can transmit to individuals when it is exchanged from one person to another. Consequently, the current study was carried out to assess the current situation of bacterial contamination of Bangladeshi paper currency. We have divided the area of Dhaka into seven sectors and each sector had five zones: hospital, super shop, wet market, bank, and transportation. Thirty-five currency notes were collected from the places mentioned above of Dhaka and each currency notes were collected in sterile falcon tubes. After processing, the samples were cultured on selective & non-selective media. Bacteria colonies were primarily selected based on colony morphology and cultural traits. The isolates were further identified through biochemical tests. Antibiotic susceptibility tests of the isolates were performed following the Kirby-Bauer disk diffusion method. A total of 247 confirmed isolates of bacteria were selected from 35 different samples where Escherichia coli (22.67%) and Vibrio cholerae (10.12%), Vibrio metschnikovii (9.71%), were the predominant species, followed by Staphylococcus delphini (8.90%), Shigella spp (1.61%), Klebsiella spp (8.90%) and Citrobacter (15.38%) among 247 isolates. Among 185 gram-negative isolates, about 26.98% of species were resistant against Penicillin, 47.34% to Peptide, 20.93% against Carbapenem, and 22.72% against 4th generation Cephalosporin. On the other hand, among 62 gram-positive isolates, 44.75% were resistant to Penicillin, 64.10% to Glycopeptide, about 64.55% to Monobactam, and 23.87% were resistant to Carbapenem group. Among all the detected 247 isolates, 57.89% were multidrug-resistant bacteria. Moreover, 20.97% MDR species showed beta hemolytic pattern. Multiple antibiotic-resistant pathogenic bacteria are prevalent in paper currency regardless of their sources. This study shows that contaminated paper currency could be potential carrier for disease causing and antibiotic resistant bacteria.