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Ann Lab Med. Nov 2012; 32(6): 407–412.
Published online Oct 17, 2012. doi:  10.3343/alm.2012.32.6.407
PMCID: PMC3486934
Methicillin-resistant Staphylococcus aureus in Nasal Surveillance Swabs at an Intensive Care Unit: An Evaluation of the LightCycler MRSA Advanced Test
Hee Jin Huh, M.D.,1 Eu Suk Kim, M.D.,2 and Seok Lae Chae, M.D.corresponding author1
1Department of Laboratory Medicine, Dongguk University Ilsan Hospital, Goyang, Korea.
2Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
corresponding authorCorresponding author.
Corresponding author: Seok Lae Chae. Department of Laboratory Medicine, Dongguk University Ilsan Hospital, 27 Dongguk-ro, Ilsandong-gu, Goyang 410-773, Korea. Tel: +82-31-691-7890, Fax: +82-31-691-7902, rocky/at/dumc.or.kr
Received April 13, 2012; Revised July 23, 2012; Accepted September 19, 2012.
Abstract
Background
We compared the LightCycler MRSA advanced test (Roche Diagnostics, Germany) with enrichment culture methods to evaluate the relative diagnostic performance of the LightCycler MRSA advanced test for active surveillance in a high-prevalence setting.
Methods
A total of 342 nasal swab specimens were obtained from patients in the intensive care unit at admission and on the seventh day for follow-up. The results of LightCycler MRSA advanced test were compared to those of the enrichment culture. For discrepant results, mecA gene PCR was performed.
Results
For the detection of methicillin-resistant Staphylococcus aureus (MRSA), the LightCycler MRSA advanced test showed 98.5% sensitivity and 78.6% specificity and had positive and negative predictive values of 75.0% and 98.8%, respectively. A total of 46 samples had discrepant results between the LightCycler MRSA advanced test and enrichment culture. Of the 44 specimens that were positive in the LightCycler MRSA advanced test but negative by enrichment culture, mecA genes were detected in 37 specimens. In addition, of the original 44 cases, 21 patients had a history of MRSA colonization or infection within the last month; of those 21 specimens, 20 were positive for mecA gene as shown by PCR. Seven mecA-negative discrepant specimens comprised 3 methicillin-sensitive S. aureus-culture positive and only 2 patients had MRSA infections.
Conclusions
Despite its low specificity and positive predictive value, the LightCycler MRSA advanced test could serve as a rapid test for patients colonized with MRSA.
Keywords: Methicillin-resistant Staphylococcus aureus, Real-time polymerase chain reaction, Active surveillance
Articles from Annals of Laboratory Medicine are provided here courtesy of
Korean Society for Laboratory Medicine