Re-evaluating microbiological testing and isolation measures for suspected MRSA carriers: insights from a...

The Netherlands has one of the lowest prevalences of methicillin-resistant Staphylococcus aureus (MRSA) in Europe due to its stringent Search and Destroy policy, including isolation of suspected carriers. Unexpected MRSA detection in non-isolated patients triggers contact tracing and screening of exposed patients and healthcare workers (HCWs). Given evolving epidemiology and healthcare practices, periodic re-evaluation of control measures is essential to sustain low prevalence while minimizing burden.

This retrospective study at a Dutch tertiary hospital (2022-2024) assessed (1) diagnostic accuracy and utility of rapid MRSA PCR using Copan eSwab and Xpert MRSA NxG (Cepheid, GeneXpert); (2) proportion of unexpected MRSA among newly detected carriers; (3) transmission risk after unprotected MRSA exposure; (4) implications for optimizing screening and isolation. Data were extracted from electronic patient and laboratory records. MRSA culture and PCR results (throat, nose, rectum combined) were compared and stratified by screening indication.

Among 1939 MRSA screenings, 89 (4.6%) were positive. Major screening indications were 'foreign healthcare exposure' (42.8%; 1.6% positive), 'residing in an asylum seekers' centre' (24.9%; 7.8% positive), or 'livestock contact' (14.5%; 8.6% positive). MRSA-positive household contacts had the highest MRSA test positivity (16/87; 18.4%). Compared with culture, PCR (n = 830) showed 63.9% sensitivity and 99.2% specificity, 21% of positive PCRs were false positives (7/32). Unexpected MRSA findings triggered 78 contact investigations involving 143 patients and 1550 HCWs. Nosocomial transmission occurred in 0.3% of HCWs, none in patients. Incidental MRSA was found in 0.4% of HCWs (6/1550). 30% of patients with "unexpected MRSA" lacked known risk factors; parental origin abroad was observed in 38% (exploratory analysis). "Suspected MRSA" accounted for 23% of strict isolation days.

Current MRSA screening remains effective but could be optimized. Given the low transmission risk, limited PCR sensitivity, and low MRSA prevalence in high-risk groups, contact isolation instead of strict isolation may suffice while awaiting culture results in suspected carriers. A revised, risk-based approach could improve efficiency, reduce unnecessary isolation, and lower costs without compromising safety. As 30% of unexpected MRSA cases lacked established risk factors, updating screening criteria to include emerging risk factors may further strengthen detection and containment.