Evaluation of a real-time polymerase chain reaction assay using analyte-specific reagents for detection of methicillin-resistant Staphylococcus aureus nasal carriage.
OBJECTIVE
To validate a real-time polymerase chain reaction (PCR) assay for the detection of methicillin-resistant Staphylococcus aureus (MRSA) that is capable of accommodating 30 patient samples in a single batch without compromising the level of sensitivity and specificity associated with PCR testing.


METHODS
A real-time PCR analyte-specific reagent (ASR) assay was compared to conventional culture methods using dual swab samples collected from the nares of 151 patients.


RESULTS
Of the 151 specimens, 49 (32%) were positive for MRSA by PCR, whereas 40 (26%) were positive by culture methods. The Roche LightCycler 2.0 (Roche Diagnostics, Indianapolis, Indiana, U.S.A.) and its associated ASRs were capable of analyzing 30 patient samples and 2 controls in < 2 hours. Current data suggest that 4-10% of our patient specimens harbor both coagulase negative Staphylococcus and S aureus in the same sample. Samples such as this are reflexed to culture, only 24% of which contain MRSA. Efficiency in the laborato-ry was greatly improved. The sensitivity, specificity, positive predictive value and negative predictive value were 100%, 92%, 82% and 100%, respectively.


CONCLUSIONS
The Roche LightCycler 2.0 PCR platform is a sensitive and efficient screening method for determining the nasal carriage of MRSA with a rapid turnaround time in the clinical laboratory.
Fodrie
Tina Y
TY
Department of Pathology, Roudebush Veterans Administration Medical Center, Indianapolis, Indiana 46202, USA.
Allen
Stephen D
SD
Blue
Deborah E
DE
Gary
Patty
P
Cheng
Liang
L
D001431:Bacteriological Techniques; D002353:Carrier State / Q000175:diagnosis / Q000382:microbiology; D046508:Culture Techniques; D004269:DNA, Bacterial / Q000032:analysis; D005189:False Positive Reactions; D006801:Humans; D016106:Methicillin Resistance; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*; D009297:Nasal Mucosa / Q000382:microbiology*; D011237:Predictive Value of Tests; D011933:Reagent Kits, Diagnostic; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D057188:Workflow
D004269:DNA, Bacterial; D011933:Reagent Kits, Diagnostic