Feasibility study of a real-time PCR test for meticillin-resistant Staphylococcus aureus in a point of care setting

Abstract

We investigated whether a commercial real-time polymerase chain reaction test for meticillin-resistant Staphylococcus aureus (MRSA) could be used as a point of care test. GeneXpert systems, on which the Xpert MRSA test is run, were installed on four wards within the Sandwell and West Birmingham Hospitals NHS Trust and in the main microbiology laboratory. Nasal samples were collected using double-headed swabs from newly admitted patients onto the four study wards. One swab was tested using the Xpert MRSA test on the ward by non-laboratory staff, the other was tested by the microbiology laboratory. In total, 988 nasal swabs were collected from 930 patients (March 2008 to June 2008). Of these, 947 processed swabs gave a valid result (MRSA positive or negative) both in the laboratory and respective ward, and there was 97.5% agreement between results obtained from the ward and from the laboratory (850 MRSA negative; 73 MRSA positive). Results for 24 swabs showed a discrepancy between the results from the ward and laboratory. MRSA testing carried out on the wards showed a sensitivity, specificity, positive predictive value and negative predictive value of 83.9, 98.8, 88.0 and 98.4, respectively, compared with the laboratory. On average the time to result for the wards was >10h quicker than the laboratory. The Xpert MRSA test performed equally well, whether carried out on the wards or by the laboratory. The major benefit of MRSA point of care testing was the large reduction in the time to obtain a result compared with the laboratory.