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Keywords:

  • antibiotic resistance;
  • coagulase-negative staphylococci;
  • coagulase-positive staphylococci;
  • euro currency;
  • persistence;
  • prevalence;
  • Staphylococcus aureus

Abstract

Aims

The study set out to sample €10 banknotes for the presence of coagulase-positive staphylococci (CPS) such as Staphylococcus aureus (S. aureus) and coagulase-negative staphylococci (CoNS) in Southern Ireland, to assess the levels of antibiotic resistance among those isolated, and determine the persistence of S. aureus on €10 banknotes and €2 coins.

Methods and Results

We report that 97% of €10 banknotes screened (n = 155) harboured multiple species of staphylococci. From the generated bank of strains, a total of 150 representative staphylococci isolates were used for further study, 71 were CPS and 79 were CoNS. Of these, we found that 62% of the staphylococci demonstrated resistance to at least one of the first-line antibiotics (52·11% of CPS isolates and 76·71% of the CoNS isolates). Resistance to multiple antibiotics was seen in 31·18% of the resistant isolates. In relation to persistence studies, S. aureus was shown to remain viable on euro banknotes and coins for significant periods (on average, 19·33 days on €10 banknotes and 16·67 days on €2 coins) as determined using bioluminescence.

Conclusions

We advocate the expansion of antibiotic surveillance programs, with a view to tracking/monitoring antibiotic resistance dissemination among environmental contaminants. Additionally, we propose that ‘cashless transactions’ should be encouraged in high-risk environments such as hospitals and healthcare settings, as well as stricter infection controls.

Significance and Impact of the Study

Although it is accepted that circulating currency has the potential to harbour disease-causing pathogens, studies investigating prevalence and persistence of such pathogens on euro currency are virtually nonexistent. In an attempt to rectify this, we examined the prevalence of staphylococci on €10 banknotes in Ireland and reported relatively high levels of antibiotic resistance among the isolates. Furthermore, we have established the persistence of S. aureus on euro currency for the first time.