Bacterial Contamination of Iranian Paper Currency and Their Antibiotic Resistance Patterns

Paper currency is used in exchange for services, and thisis why the circulation of paper currency from person to person expandsmicroorganisms.
: Paper banknotes would be a vector for transmission of pathogenic microorganisms through handling. This study aimed to determine bacterial contamination of Iranian paper currencies in circulation and their antibiotic resistance patterns.
In this study, 337 currency notes of different value were collected from markets, shops, restaurants, bus stations and banks in Kashan, Iran during April 2015 to March 2016. The currency notes transferred to microbiology laboratory and were tested for bacterial contamination using standard microbiological methods. Antibiotic resistance patterns of isolated bacteria were determined by disk diffusion method according to CLSI standards. The results and data were analyzed using descriptive statistics.
Of 337 currency notes, 262 (77.7%) were identified with bacterial contamination. Bacteria isolated from currency notes were as follows: Bacillus spp 113 (43.1%), coagulase-negative Staphylococci 99 (37.7%), Escherichia coli 20 (7.6%), Enterococci species 14 (5.3%), Staphylococcus aureus 8 (3.1%), Klebsiella spp 4 (1.5%), Shigella species 2 (0.8%), Pseudomonas species 2 (0.8%). The most and least contaminated currency notes were 50000 and 500 Rials, respectively. The most resistance rates in gram negative rods were against nalidixicacid, and ampicillin. Also most resistance rates in Staphylococcus aureus, coagulase-negative Staphylococci and Enterococci species were against ampicillin, erythromycin and tetracycline.
Our study revealed that the bacterial contamination among Iranian paper currency in circulation especially those obtained from certain sources including shops and bus stations is high and in most cases these bacterial isolates are antibiotic resistant strains.