Real-time polymerase chain reaction detection of methicillin-resistant Staphylococcus aureus: impact on nosocomial transmission and costs.
OBJECTIVE
To assess the impact of real-time polymerase chain reaction (PCR) detection of methicillin-resistant Staphylococcus aureus (MRSA) on nosocomial transmission and costs.


METHODS
Monthly MRSA detection rates were measured from April 1, 2000, through December 31, 2005. Time series analysis was used to identify changes in MRSA detection rates, and decision analysis was used to compare the costs of detection by PCR and by culture.Setting. A 1,200-bed, tertiary care hospital in Canada.


METHODS
Admitted patients at high risk for MRSA colonization. MRSA detection using culture-based screening was compared with a commercial PCR assay.


RESULTS
The mean monthly incidence of nosocomial MRSA colonization or infection was 0.37 cases per 1,000 patient-days. The time-series model indicated an insignificant decrease of 0.14 cases per 1,000 patient-days per month (95% confidence interval, -0.18 to 0.46) after the introduction of PCR detection (P=.39). The mean interval from a reported positive result until contact precautions were initiated decreased from 3.8 to 1.6 days (P<.001). However, the cost of MRSA control increased from Can$605,034 to Can$771,609. Of 290 PCR-positive patients, 120 (41.4%) were placed under contact precautions unnecessarily because of low specificity of the PCR assay used in the study; these patients contributed 37% of the increased cost. The modeling study predicted that the cost per patient would be higher with detection by PCR (Can$96) than by culture (Can$67).


CONCLUSIONS
Detection of MRSA by the PCR assay evaluated in this study was more costly than detection by culture for reducing MRSA transmission in our hospital. The cost benefit of screening by PCR varies according to incidences of MRSA colonization and infection, the predictive values of the assay used, and rates of compliance with infection control measures.
Conterno
L O
LO
Division of Infectious Diseases, Marilia Medical School, Marilia, Sao Paulo, Brazil.
Shymanski
J
J
Ramotar
K
K
Toye
B
B
van Walraven
C
C
Coyle
D
D
Roth
V R
VR
D002170:Canada; D003362:Cost-Benefit Analysis; D003428:Cross Infection / Q000191:economics / Q000635:transmission; D006746:Hospital Bed Capacity, 500 and over; D006801:Humans; D017053:Infection Control / Q000191:economics* / Q000379:methods; D016106:Methicillin Resistance / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D018571:Sentinel Surveillance; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000235:genetics / Q000635:transmission; D013211:Staphylococcus aureus / Q000235:genetics* / Q000302:isolation & purification