Carbapenems, largely recognised as one of the last-line of defences against multidrug-resistant (MDR) bacterial infections, is now facing threats of resistance and reduced effectiveness. While carbapenamase-producing Enterobacterales (CPE) infection control practices are based on the paradigm that detected carriers in the hospital transmit the bug to other patients through person-to-person contact within the same ward or hospital, the involvement of plasmid-mediated transmission has resulted in the rise of hidden reservoirs. In particular, the environment, healthcare workers, hospital equipment and instruments are some of the potential sources of CPE transmission, which are currently not adequately addressed by existing infection control protocols.
Since 2010, Singapore has reported a rise in CPE infections across all public hospitals. The most common species detected were Klebsiella pneumoniae (K. pneumoniae), Escherichia coli (E. coli) and Enterobacter cloacae (E. cloacae), with blaKPC-2, blaNDM-1, blaOXA-181 and blaOXA-48 as the predominant carbapenemase genes. The Carbapenemase-producing Enterobacteriaceae in Singapore (CaPES) study group, initiated in 2013, was aimed at integrating clinical and molecular epidemiology to better understand risk factors, clinical outcomes and transmission patterns of carbapenem-resistant Enterobacterales (CREs) in Singapore. As part of a retrospective CaPES study, over 1,000 clinical and surveillance samples from September 2010 to April 2015 were whole-genome sequenced. Transmission analysis was performed to provide insights into the dynamics of CPE introduction and dissemination in healthcare facilities since majority of CPE transmission over the study period were genomically linked, either by clonal or plasmid-mediated transmission. While clonal transmission decreased following introduction of infection prevention and control measures, plasmid-mediated transmission persisted for a much longer period and accounted for a significant prevalence of CPE at a population-level.
CPE infections remain a critical public health concern in Singapore, and a national network aimed at research, surveillance and prevention is key in developing effective interventions for future outbreaks.