SHORT REPORT Characterization of staphylococci contaminating automated teller machines in Hong Kong M. ZHANG 1 , M. O’DONONGHUE 2 AND M. V. BOOST 1 * 1 Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hong Kong SAR, China 2 School of Nursing, The Hong Kong Polytechnic University, Hong Kong SAR, China (Accepted 17 September 2011; first published online 19 October 2011) SUMMARY Environmental staphylococcal contamination was investigated by culture of 400 automated teller machines (ATMs). Isolates were characterized for antibiotic and antiseptic susceptibility, carriage of antiseptic resistance genes (QAC genes), and spa types. MRSA, which was similar to local clinical isolates, was present on two (0 . 5%) of the 62 (15 . 5%) ATMs that yielded Staphylococcus aureus. QAC genes were more common in coagulase-negative staphylococci (qacA/B 26 . 0%, smr 14%) than S. aureus (11 . 3% qacA/B, 1 . 6% smr). QAC-positive isolates had significantly higher minimum inhibitory concentrations/minimum bactericidal concentrations to benzalkonium chloride and chlorhexidine digluconate. QAC gene presence was significantly associated with methicillin and tetracycline resistance. Survival of staphylococci, including MRSA, on common access sites may be facilitated by low disinfectant concentrations, which select for disinfectant-tolerant strains, while co-selecting for antibiotic-resistance determinants. Disinfection procedures should be performed correctly to help prevent spread of resistant pathogens from reservoirs in the community. Key words : Disinfectant, enterotoxin, environment, MRSA, qacA/B. Methicillin-resistant Staphylococcus aureus (MRSA), for many years an important hospital-associated pathogen, has recently emerged in the community, leading to increased public concern about the risks of infection, including from contamination of the environment. Although other body sites may be col- onized, the most important niche for S. aureus is the anterior nares and colonization at this site increases the risk for clinical infection [1]. However, investi- gations of community-associated MRSA (CA-MRSA) outbreaks have failed to isolate the strain from the nares of any of the infected subjects, leading to suggestions that CA-MRSA may transmit through sharing or contact with common items. This is sup- ported by reports of clusters of CA-MRSA infection in athletes, military recruits and prisoners who share common facilities [2]. However, there are also isolated infections in patients who do not participate in sports or belong to these at-risk groups. Several studies have demonstrated that although cases of CA-MRSA have increased rapidly, rates of MRSA colonization in non-healthcare workers in the community remain low. Sampling of household con- tacts of MRSA-colonized patients frequently yields low rates of other colonized subjects [3] and, thus, the * Author for correspondence : Dr M. V. Boost, Associate Professor, Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China. (Email : htmboost@polyu.edu.hk) Epidemiol. Infect. (2012), 140, 1366–1371. f Cambridge University Press 2011 doi:10.1017/S095026881100207X