Introduction
Globally, money is one of the items most
frequently passed from hand to hand. During its passing, money can get
contaminated and may thus plays a role in the
Transmission of microorganisms to other
people. For example money may get contaminated with microorganisms from the
respiratory- and gastro-intestinal tract during counting. Money is not usually
suitable for the survival of microorganisms, except for some that are resistant
to external conditions and non-resistant forms of spores . In addition, the
general hygiene levels of
a community or society may contribute to
the amount of microbes found on coins and notes, and thus the chance of
transmission during handling of money.
While antimicrobial resistance has steadily
been increasing e.g. with Extended-Spectrum Beta Lactamases (ESBL) producing Escherichia coli and
Klebsiella spp , contaminated banknotes and coins contribute
to the transmission of these multi-drug resistant microorganisms in the
community.
While the kind of isolated bacteria between
studies can vary, due to the methods used, season, environmental conditions,
sort of money (coin or banknote) or local
Community flora, in general, Gram positive
bacteria was the most predominant.
The aim of this study was to ascertain the
survival status of bacteria including Staphylococcus aureus,E. coli, and Vancomycin-Resistant
Enterococci (VRE) on
banknotes from different countries and the
transmission of bacteria to olunteers getting in contact with contaminated banknotes
under experimental conditions.
Material and method
This study was conducted in the medical
microbiology laboratory of Canisius Wilhelmina Ziekenhuis in 2012.
The first step of study was to inoculate a
few colonies of methicillin-resistant S.aureus (MRSA) ATCC 43300, Vancomycin-resistant Enterococcus feaecium
(VRE) ATCC51559 and an extended spectrum of beta lactamases
(ESBL) producing E. coli ATCC 25922 strains
into 5 ml Tryptic Soy broth medium in tubes, which then were incubated at 35°C
for 24-h. All banknotes were inoculated with 8 dilutions of a serial dilution
of the original inoculum,
by spreading 100 μl from each tube onto
different described areas of the banknotes which were previously sterilized
under ultraviolet light radiation. As a control, 100 μl of all dilutions were inoculated onto
Columbia agar.
After a 24-h incubation at 35°C, all
colony-forming units were counted, and the number of bacteria given onto the banknotes
calculated. All experiments were done in duplicate.
All banknotes were dried in ambient
conditions.
Cultures from the banknotes were taken by a
moistened swab (0.9% saline) after 3-h, 6-h and 24-h. Swabs were directly
inoculated onto Columbia agar and into tubes
with 1 ml 0.9% saline. 100 μl from each
tube were spread onto Columbia agar.
For the second part of the study,
methicillin sensitive S.aureus (MSSA) ATCC 25923 and non-extended spectrum beta lactamases producing E. coli ATCC 35218 strains were inoculated into 5 ml (Tryptic Soy broth),
incubated
at 35 ° C for 24-h, A 100 μl inoculum of
MSSA was spread onto one side of a US Dollar and
Romanian Leu (RON) banknote, that has previously
been sterilized
by ultraviolet light radiation. In the same
way, E. coli was spread onto one side of a Euro and a
Romanian Leu (RON) banknote. After the banknotes were
dried for 30 minutes, three people whose hands were
disinfected by alcohol-based hand rub, and washed with
sterile 0.9% saline, rubbed the banknotes for 30
seconds, respectively.
After rubbing, the fingers were sampled by
placing the fingertips directly on the 5%
sheep-blood agar plate.
Semi-quantitative colony counts were
established after a 24-h incubation period for each person.
After the study was completed, all of the
banknotes were sterilized by ultraviolet light radiation.
The banknotes were not damaged during the study and brought into re-circulation.
Results
Euro, US Dollar, Canadian Dollar, Croatian
Luna, Romanian Leu (RON), Moroccan Dirham, and Indian Rupee banknotes were
included into the first part of the study. Cultures of the Romanian Leu yielded
all 3 multi-drug resistant pathogens; MRSA, VRE and ESBL-producing E. coli. The
Canadian and (US) American Dollar only yielded MRSA; the Euro only
ESBL-producing E. coli, the Indian Rupee only VRE, and the Croatian Luna did
not yield any of the 3 microorganisms (Table 1). The Romanian Leu yielded all
three microorganisms after both, three and six hours of drying, and it was the
only currency which yielded a microorganism, VRE, after one day of drying. The
Canadian Dollar yielded MRSA and VRE after six hours of drying. The Euro
yielded ESBL-producing E. coli in the 3 and 6-h cultures, VRE in the 3-h
culture, but at no time MRSA (Table 2).
The second part of the study, the transmission
experiments, was based on the results of the first part. Consequently, the
Euro, Romanian Leu and US Dollar was used, after inoculation with E. coli
(Euro) and MSSA (US Dollar), or both (Leu), respectively. The transmission did
not succeed after contact with the contaminated Euro banknotes, in any of 3
subjects (Table 3). Transmission of the Romanian Leu (E. coli and MSSA) and of
the US Dollar (MSSA) was successful, with the amount of colony forming units
slightly higher after contact with the Leu.
Our experiments showed that the polymer
structure of the Romanian Leu banknote allows growth and transmission of
multi-drug resistant pathogens. This, in theory, could contribute to the
transmission of microorganisms within the Romanian community. Countries using
polymer-based banknotes should take this into consideration, especially, if a
currency is not exclusively used within one country, such as the Euro and US
Dollar. Despite prolonged survival of E. coli on the Euro (up to 6 hours),
transmission to the volunteers did not succeed. In contrast, US and Canadian
Dollar showed significant and prolonged carriage of MRSA. S. aureus was
transmissible from the US Dollar and thus indicates, that banknotes may play a
role in the transmission of MRSA within the community. The Croatian Kuna was
found to, unexpectedly, not allow growth of any of the multi-drug resistant
microorganisms tested. While we could not find further information on the
content and make-up of this currency, it could be interesting for other countries
who want to eliminate banknotes as a source of bacterial transmission.
Gram-positive and –negative microorganisms, including staphylococci, bacilli,
and various enterobacteriaceae, have been found on banknotes in multiple
countries, such as in Iran and Turkey .
Money is frequently touched during daily
life. The observed differences between the various currencies were unexpected
and were not based on different climate conditions or hygiene levels, since all
experiments were performed at the same conditions, using previously sterilized
banknotes. While further studies would be needed to establish transmission of
multi-drug resistant microorganisms through contact with money, or experiments
show that this may be a potential pathway, especially in countries that use
polymer-based banknotes.
Conclusion
Our experiments showed that the polymer
structure of the Romanian Leu banknote allows growth and transmission of
multi-drug resistant pathogens. This, in theory, could contribute to the
transmission of microorganisms within the Romanian community. Countries using
polymer-based banknotes should take this into consideration, especially, if a
currency is not exclusively used within one country, such as the Euro and US
Dollar. Despite prolonged survival of E. coli on the Euro (up to 6 hours),
transmission to the volunteers did not succeed. In contrast, US and Canadian
Dollar showed significant and prolonged carriage of MRSA. S. aureus was
transmissible from the US Dollar and thus indicates, that banknotes may play a
role in the transmission of MRSA within the community. The Croatian Kuna was
found to, unexpectedly, not allow growth of any of the multi-drug resistant
microorganisms tested. While we could not find further information on the
content and make-up of this currency, it could be interesting for other
countries who want to eliminate banknotes as a source of bacterial
transmission. Gram-positive and –negative microorganisms, including
staphylococci, bacilli, and various enterobacteriaceae, have been found on
banknotes in multiple countries, such as in Iran and Turkey.
Money is frequently touched during daily
life. The observed differences between the various currencies were unexpected
and were not based on different climate conditions or hygiene levels, since all
experiments were performed at the same conditions, using previously sterilized
banknotes. While further studies would be needed to establish transmission of
multi-drug resistant microorganisms through contact with money, or experiments
show that this may be a potential pathway, especially in countries that use
polymer-based banknotes.
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Ref : Antimicrobial Resistance and Infection Control 2013 - Money and transmission of bacteria
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