Natural clearance of colonization with vancomycin-resistant Enterococcus and carbapenemase-producing Enterobacterales: a 13-year study among territory-wide residents of residential care home for the elderly in Hong Kong.

BACKGROUND

Vancomycin-resistant Enterococcus (VRE) and carbapenemase-producing Enterobacterales (CPE) cause outbreaks in hospitals and the community. There is limited literature on the clearance time of VRE and CPE colonization. We reported the natural clearance time of VRE and CPE among residents of the Residential Care Home for the Elderly (RCHE) and the factors associated with prolonged colonization.

METHODS

This retrospective study reviewed cases of VRE and CPE colonization reported to the Centre for Health Protection, Department of Health, Hong Kong Special Administrative Region from 1 January, 2012 to 31 December, 2024. We reviewed the demographic characteristics and outcomes of the VRE and CPE cases when they were cleared of the bacteria or died during the follow-up period, up to 31 December 2024. Clearance of VRE and CPE was defined as negative culture results for at least two and three consecutive specimens collected at least 48 h apart at the RCHE respectively. We compared the clearance time of VRE and CPE using the Kaplan-Meier method and determined the factors influencing the duration of clearance by univariate and multiple Cox regression.

RESULTS

A total of 3626 VRE cases and 4434 CPE cases were followed up. CPE cases tended to be older and had a higher proportion of females compared to VRE cases. There was no statistical difference in the types of homes between the two groups. The mortality rate of VRE (25.7%) was similar to that of CPE (25.1%). It was found that the carriage duration of CPE was significantly longer than that of VRE, as tested by the log-rank test (p < 0.01). Half of the VRE and CPE cases will clear the bacteria by 85 days and 131 days, respectively. The carriage duration for the majority (90%) of VRE and CPE cases was 400 and 818 days, respectively. After adjusting for all associated factors, a longer length of stay for readmission to hospitals and lower occupancy rates in RCHEs were significantly associated with prolonged carriage status.

CONCLUSIONS

The natural clearance duration of VRE and CPE provides useful information to improve guidelines of screening of previously colonized patients, and duration of contact precautions to prevent transmission of these resistant organisms among the vulnerable groups.