MRSA screening in early neurological and neurosurgical rehabilitation

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Strains of methicillin-resistant Staphylococcus aureus (MRSA) are of major economic and health-related importance to early neurological and neurosurgical rehabilitation. It is crucial to identify MRSA-carriers as soon as possible upon admission in order to prevent transmissions and to initiate contact precautions and decolonization. The present study focuses on validity of a polymerase chain reaction (PCR) test to identify MRSA genetic material from nasopharyngeal samples (BD MAX MRSA XT, BD Diagnostics, Heidelberg, Germany) of early neurological and neurosurgical rehabilitation patients. PCR-results were compared to gold standard (culture). In 2013, 66 patients were tested using PCR and incubation within one week after admission. Sensitivity of PCR was 84.6 %, specificity 86.6 %. Positive predictive value (PPV) was only 61.1 %, while negative predictive value was as high as 95.8 %. In 39 cases, PCR and subsequent culture were done within one day, leading to a sensitivity of 100 % and a specificity of 90.3 %. In this subgroup, PPV was 72.7 %, NPV 100 %. The results from the study suggest that incubation should quickly follow a positive PCR finding (within 24hours) in order to verify MRSA colonization. High NPV (95.8 resp. 100 %) indicate that PCR negative patients very likely are not colonized with MRSA. A positive PCR test is less reliable (due to false positive results) and should be followed by incubation in due course in order to avoid unnecessary contact precautions.