screen at-risk patients, thus identifying potential carriers who may serve as reservoirs for sustained horizontal trans- mission.1e3 Active surveillance is most often initiated in outbreak settings with the aim of detecting unknown reser- voirs. This strategy is based on the assumption that colonized patients may perpetuate transmission and that early identifi- cation with isolation will curb this. However, the clinical relevance and the subsequent impact of infection prevention and control measures based on active surveillance cultures remain to be determined.4 To date, the screening of patients for multidrug-resistant Gram-negatives, including CPE, has relied primarily on culture. Various methods of culture have been investigated, yet a universally applicable method remains elusive.
The main drawback to culture from an infection preven- tion and control (IPC) perspective is the prolonged turnaround time of at least 24e72h, during which unnecessary IPC measures may be instituted while waiting for a result. Therefore PCR-based assays with their rapid turnaround time and high sensitivity are an attractive alternative. However, the role of PCR-based screening methods has yet to be fully elucidated.5 The multitude of carbapenemase genes and ubiquitous nature of Enterobacteriaceae may compound the problems associated with PCR-based screening of CPE. In South Africa, multiplex PCR-based screening methods are currently employed, by various laboratories, to assist in the detection of CPE in at-risk patients. Various types of CPE, including NDM-1, KPC and OXA-48-like, have been detected and reported in South Africa.6e8
However, this strategy of PCR-based screening for multiple CPE was largely prompted by an outbreak of NDM-1 at a private hospital with a subsequent need for rapid detection of colo- nized patients. PCR-based screening for CPE has recently garnered interest, although usually as a single or duplex PCR in an established outbreak or high prevalence setting.9e11 The applicability of a multiplex PCR screening method for surveil- lance purposes has not been established and the validity of such a method remains to be determined. We sought to assess the applicability of such a strategy in the context of a routine diagnostic laboratory that processes samples from a multitude of different hospitals in the Gauteng region.