Multidrug-resistant organism carriage among residents from residential care homes for the elderly in Hong Kong: a prevalence survey with stratified cluster sampling

A point prevalence survey was conducted to study the epidemiology of and risk factors associated with multidrug-resistant organism carriage among residents in residential care homes for the elderly (RCHEs). A total of 20 RCHEs in Hong Kong were selected by stratified single-stage cluster sampling. All consenting residents aged ≥65 years from the selected RCHEs were surveyed by collection of nasal swab, axillary swab, rectal swab or stool on one single day for each home. Specimens were cultured and analysed for methicillin-resistant (MRSA), multidrug-resistant (MDRA, defined as concomitant resistant to fluoroquinolones, carbapenems, aminoglycosides, cephalosporins and beta-lactam with or without beta-lactamase inhibitors), vancomycin-resistant (VRE), and carbapenemase-producing (CPE). One third of the MRSA-positive samples were selected at random for molecular typing; all positive MDRA, VRE and CPE samples were tested for molecular typing. Demographic and health information of residents including medical history, history of hospitalisation, antimicrobial usage, and use of indwelling catheters were collected to determine any associated risk factors. Samples of 1028 residents from 20 RCHEs were collected. Prevalence of MRSA was estimated as 30.1% (95% confidence interval [CI]=25.1%-35.6%) and MDRA 0.6% (95% CI=0.1%-4.1%). No residents carried VRE nor CPE. Residents living in privately run RCHEs were associated with MRSA carriage. Non-Chinese residents were associated with MRSA carriage with borderline significance. This survey provided information about multidrug-resistant organism carriage among RCHE residents. This information will enable us to formulate targeted surveillance and control strategies for multidrug-resistant organisms.