Dirty Croatian money: how big is a threat?
Aim: Objective of this study was to determine extent of bacterial contamination expressed as colony forming units (CFU) on Croatian Kuna (HRK) banknotes and coins.
Methods: 120 pieces of banknotes and coins were collected for the experiment, 10 bills of 10, 20, 50, 100, 200 and 500 HRK and 10 coins of 10, 20 and 50 Croatian Lipa and 1, 2 and 5 HRK. At the Department of Microbiology and Parasitology, Faculty of Medicine, University of Osijek, swabs were taken from money, moistened in saline, planted on blood agar and incubated for 24 hours under ambient conditions at 37 °C. After growing the bacteria, CFU were counted and replanted for further identification, which was performed in accordance with the microbiological professional standards.
Results: In total, 739 bacterial CFU were grown in six species of bacteria: Staphylococcus epidermidis, Staphylococcus saprophyticus, Streptococcus viridans, Bacillus spp., Klebsiella spp., Neisseria spp. Almost 30% of the money was bacteriological clean. There were no statistical difference between the prevalence of bacterial contamination of banknotes and coins. The most common bacteria isolated was S. epidermidis (86.33%) with statistically significance both on banknotes and coins (p<0.0001).
Conclusion: The identified bacterial species are mostly part of the normal human flora. Pathogenic, and potentially pathogenic bacterial species were not found on Croatian banknotes and coins in a respect of one colony of Klebsiella sp.
Keywords: bacterial contamination, normal bacterial flora, banknotes, coins