Screening of Carbapenemase-producing organisms and Vancomycin Resistant Enterococci by a molecular approach: impact and lessons learned

Background Rapid detection of carriers of Emerging eXtensively Drug Resistant bacteria (eXDR), especially CPOs (Carbapenemase-producing organisms), and VREs (Vancomycin Resistant Enterococci) is essential for controlling the spread of these bacteria and preventing infections. The impact of PCR on the turnaround time (TAT) for eXDR detection was evaluated in comparison with culture under routine laboratory conditions, i.e. without carrying out analyses at night and at weekends. The number of screening tests, contact patients, secondary cases and the real cost of healthcare were also assessed. Methods A prospective before-and-after study was performed in a French university hospital. Phase 1 (culture) took place between February and September 2022 and phase 2 (PCR), between September and March 2023. The TAT was defined as the time from sample collection to delivery of results to the infection control team. Patients over 18 with one or more eligibility criteria for rectal screening (history of hospitalisation abroad; eXDR carriers; multiple hospitalisation; transfer from another hospital or nursing home; contact patients) were included. Two PCRs were used: the BD MAX™ Check-Points CPO kit, and the VIASURE Vancomycin resistance Real Time PCR Detection Kit. This study was registered on ClinicalTrials.gov (NCT05200546). Results During phases 1 and 2, respectively 2049 and 1861 patients were included. Sixteen patients were found to be positive for the first time in phase 1 and 25 in phase 2. The median TAT for eXDR newly positive detection was significantly shorter in phase 2 (22.7h, [IQR: 16.0-41.3]) versus phase 1 (43.5h, [31.9–69.7]; p = 0.001) without changing the laboratory's opening hours. The median number of screening tests per day, of contact cases and of secondary cases did not differ significantly between the 2 phases. When PCR screening was performed within 48 hours of patient admission, there was a significant decrease in the median number of contacts. Hospitalisation costs for patients were similar regardless of the eXDR identification technique used. Conclusions The strategy of rapid rectal screening based on PCR significantly reduces the TAT to obtain results, particularly for newly positive patients in a low-endemic context.