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Validation of the FluoroType® MRSA assay for the rapid identification of methicillin-resistant Staphylococcus aureus directly from patient material
Journal of Microbiological Methods 107 (2014) 71–73
Contents lists available at ScienceDirect
Journal of Microbiological Methods journal homepage: www.elsevier.com/locate/jmicmeth
Note
Validation of the FluoroType® MRSA assay for the rapid identification of methicillin-resistant Staphylococcus aureus directly from patient material Ulrich Eigner ⁎, Anke Veldenzer, Martin Holfelder Limbach Laboratory, Heidelberg, Germany
a r t i c l e
i n f o
Article history: Received 10 July 2014 Received in revised form 15 August 2014 Accepted 16 August 2014 Available online 2 September 2014
a b s t r a c t We performed the first evaluation study of the new HyBeacon based FluoroType® MRSA assay for the detection of MRSA directly from 617 patient specimens. Using culture as the reference method sensitivity and specificity were higher than 95%. Results were available within 2.5 h, including DNA extraction. © 2014 Elsevier B.V. All rights reserved.
Keywords: MRSA PCR Validation Rapid test Staphylococcus aureus
PCR-based rapid tests have been established as an important tool for effective and fast MRSA management. There are several detection formats available like line probe assays, lateral flow dip-sticks, and real-time PCR using fluorescence detection techniques (Stürenburg, 2009; Dalpke et al., 2012; Eigner et al., 2012; Holfelder et al., 2006; Huh et al., 2012; Paule et al., 2007; Rossney et al., 2008; Wolk et al., 2009). In diagnostic laboratory routine PCR tests require high reliability, short time-to-result, easy handling and cost-efficiency. According to this topic, we tested the performance of the new FluoroType® MRSA assay (Hain Lifescience, Germany) for the detection of MRSA directly from patient material. The FluoroType® MRSA test is based on the HyBeacon fluorescence technology (French et al., 2001). HyBeacon probes are single-stranded oligonucleotides labelled with fluorescent dyes. In the single stranded HyBeacon oligonucleotide emission of the fluorescent dyes is inhibited by neighbouring nucleosides. Hybridisation of the HyBeacon probe to a complementary target sequence leads to an increase in fluorescence due to separation of the fluorophores from the vicinity of the nucleosides (French et al., 2001). The FluoroType® MRSA test is performed on the FluoroCycler (Hain Lifescience). The new PCR-test was compared to our established diagnostic procedure. The study was divided into two parts. In the first part of the study, swab specimens of patients who showed no MRSA colonisation or infection in anamnesis were randomly collected in two hospitals in Heidelberg (Agaplesion Bethanien Hospital; St. Vincentius Hospital). The study has been approved by the responsible ⁎ Corresponding author at: Labor Limbach, Im Breitspiel 15, 69126 Heidelberg, Germany. Tel.: +49 6221 3432 192; fax: +49 6221 3432 212. E-mail address: [email protected] (U. Eigner).
http://dx.doi.org/10.1016/j.mimet.2014.08.007 0167-7012/© 2014 Elsevier B.V. All rights reserved.
ethic committee (State Medical Chamber, Baden-Wuerttemberg, Germany, 2011-09-13). The second part of the study comprised specimens from hospitals and medical practices that were sent to our routine laboratory for bacteriological testing. The FluoroType® MRSA assay results were compared to cultural findings. Specimens comprised swabs from nose, throat, skin, and wound and other specimens. For collection and transport of the specimens, swabs with Amies gel medium (with and without charcoal) or liquid Stuart medium were used (all from Copan, Italy). For the FluoroType® MRSA test, the swab was first inoculated in SpheroLyse® suspension, provided with the assay, and then used for inoculation of CHROMagar MRSA (Becton Dickinson, Heidelberg, Germany), CNA agar and thioglycollate broth (Becton Dickinson). The CHROMagar MRSA and the CNA agar plate were incubated at 35 °C for 48 h and evaluated after 24 h and 48 h. The thioglycollate broth was incubated for 24 h and then inoculated on CNA agar and CHROMagar for each specimen. Staphylococcus aureus-colonies were identified by MALDI Biotyper (Bruker Daltonics, Bremen). MRSA detection from cultured MRSA colonies was realized by a PCR-based assay (GenoType MRSA, Hain Lifescience) detecting the mecA gene and S. aureus specific DNA structures. The performance of the FluoroType® MRSA was assessed in comparison to culture by calculation of sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV). In total, 405 specimens were collected for the prospective study part. All of the 15 culturepositive specimens were correctly detected by FluoroType® MRSA. No false-negative results were observed. Of 389 culture-negative specimens the FluoroType® MRSA showed negative results for 386 specimens. 3 culture-negative specimens were tested positive by FluoroType® MRSA.
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U. Eigner et al. / Journal of Microbiological Methods 107 (2014) 71–73
Table 1 Performance of the FluoroType® MRSA assay compared to culture (n = 404 specimens, randomly collected in two hospitals). FluoroType® MRSA
Culture positive (n) Culture negative (n)
Compared to culture
Positive (n)
Negative (n)
Sensitivity (%)
Specificity (%)
PPV (%)
NPV (%)
15 3
0 386
100
99.2
83.3
100
Table 2 Performance of the FluoroType® MRSA assay compared to culture (n = 212 specimens, collected in the routine laboratory). FluoroType® MRSA
True-positive (n) True-negative (n)
Compared to true-positive/true-negative results
Positive (n)
Negative (n)
Sensitivity (%)
Specificity (%)
PPV (%)
NPV (%)
82 5
0 125
100
96.1
94.2
100
One specimen showed inhibition with the FluoroType® MRSA test and was therefore evaluated as an invalid result. The specimen originated from a decubitus wound of a patient who was not treated with antibiotics and who showed no MRSA colonisation or infection in anamnesis. This corresponds to an inhibition rate of 0.25% for FluoroType® MRSA. For the retrospective study part 212 specimens were tested in total. All 82 culture-positive specimens were tested positive by the FluoroType® MRSA test. 125 culture-negative specimens were congruent negative with the PCR test. For 5 culture-negative specimens FluoroType® MRSA showed a positive result. The performance data of the FluoroType® MRSA assay are also shown in Tables 1 and 2. Sensitivity and specificity as well as NPV and PPV of the FluoroType® MRSA assay were comparable to other assays targeting the regions of the open reading frame orfX and the staphylococcal cassette chromosome (SCCmec), namely the real-time PCR assays BD GeneOhm MRSA, BD MAX MRSA (both BD Diagnostics, Sparks, MD), and GeneXpert MRSA (Cepheid, Sunnyvale, CA, USA), and the LightCycler MRSA advanced test (Roche Diagnostics, Mannheim, Germany) (Dalpke et al., 2012; Huh et al., 2012; Paule et al., 2007; Rossney et al., 2008; Wolk et al., 2009). In these publications culture was also the method of comparison. The mean sensitivity of all tests was N 90% and the NPV N95%. For the Xpert MRSA assay sensitivity was reduced for throat specimens (75%) (Rossney et al., 2008). One author also reported a lower sensitivity of the PCR tests (b 90%) when compared to the highly sensitive broth enrichment culture (Wolk et al., 2009). The sensitivity of the FluoroType MRSA test was not influenced by these parameters. As discussed previously for other PCR assays (Dalpke et al., 2012; Eigner et al., 2012; Holfelder et al., 2006; Huh et al., 2012; Paule et al., 2007; Rossney et al., 2008; Wolk et al., 2009), there are several circumstances that can lead to PCR-positive/culture-negative results and results which lead to a decreased PPV. These include strains with SCCmec lacking a functional mecA gene (mecA-drop-out strains) (Donnio et al., 2005), presence of nonviable or non-cultivatable MRSA load (Huletsky et al., 2004), a higher sensitivity of PCR compared to culture (Rossney et al., 2008) or bacterial loads near the detection limit yielding inconsistent results upon repeated testing. One of these reasons might explain the false-positive specimens with the FluoroType® MRSA. In contrast to the studies of Paule et al. (2007) and Rossney et al. (2008), the results of this study were not amended by including patients' MRSA history or other clinical findings. The turnaround time of the FluoroType® MRSA assay is approximately 30 min for sample setup and DNA isolation and about 2 h for amplification and detection and therefore comparable to other rapid MRSA-PCR assays (Hombach et al., 2010). The SpheroLyse DNA isolation kit was easy to handle and released a reliable quantity and quality of DNA for PCR amplification. Growth of MRSA on the selective agar- and broth media was not inhibited after elution of the swabs in SpheroLyse suspension (pre-validation, data not shown). The ready-for-use amplification
premixes enabled convenient handling of the reagents and manual hands-on time was reduced to 10 min. The results of the FluoroType® MRSA-PCR assay were analysed automatically by the test-specific software. We conclude that the FluoroType® MRSA assay shows rapid, sensitive and specific performance results for the direct detection of MRSA in clinical swab specimens. Acknowledgements We thank Ulrike Betz for her excellent technical support. We thank Dr. Christine Wittmann-Jennwein (Agaplesion Bethanien Hospital, Heidelberg) and Dr. Peter Stiefel and Renate Billmaier (St. Vincentius Hospital, Heidelberg) for their continuous collaboration. PCR kits were supplied by Hain Lifescience. U.E. and M.H. have received speaker's honorarium from Hain Lifescience. We declare no conflict of interest. References Dalpke, A.H., Hofko, M., Zimmermann, S., 2012. Comparison of the BD Max methicillinresistant Staphylococcus aureus (MRSA) assay and the BD GeneOhm MRSA achromopeptidase assay with direct- and enriched-culture techniques using clinical specimens for detection of MRSA. J. Clin. Microbiol. 50 (10), 3365–3367 (Oct). Donnio, P.Y., Oliveira, D.C., Faria, N.A., Wilhelm, N., Le Coustumier, A., de Lencastre, H., 2005. Partial excision of the chromosomal cassette containing the methicillin resistance determinant results in methicillin-susceptible Staphylococcus aureus. J. Clin. Microbiol. 43 (8), 4191–4193 (Aug). Eigner, U., Veldenzer, A., Fahr, A.M., Holfelder, M., 2012. Retrospective evaluation of a PCR based assay for the direct detection of methicillin-resistant Staphylococcus aureus in clinical specimen. Clin. Lab. 58 (11–12), 1319–1321. French, D.J., Archard, C.L., Brown, T., McDowell, D.G., 2001. HyBeacon probes: a new tool for DNA sequence detection and allele discrimination. Mol. Cell. Probes 15, 363–374. Holfelder, M., Eigner, U., Turnwald, A.M., Witte, W., Weizenegger, M., Fahr, A., 2006. Direct detection of methicillin-resistant Staphylococcus aureus in clinical specimens by a nucleic acid-based hybridisation assay. Clin. Microbiol. Infect. 12 (12), 1163–1167 (Dec). Hombach, M., Pfyffer, G.E., Roos, M., Lucke, K., 2010. Detection of methicillin-resistant Staphylococcus aureus (MRSA) in specimens from various body sites: performance characteristics of the BD GeneOhm MRSA assay, the Xpert MRSA assay, and brothenriched culture in an area with a low prevalence of MRSA infections. J. Clin. Microbiol. 48 (11), 3882–3887 (Nov). Huh, H.J., Kim, E.S., Chae, S.L., 2012. Methicillin-resistant Staphylococcus aureus in nasal surveillance swabs at an intensive care unit: an evaluation of the LightCycler MRSA advanced test. Ann. Lab. Med. 32 (6), 407–412 (Nov). Huletsky, A., Giroux, R., Rossbach, V., Gagnon, M., Vaillancourt, M., Bernier, M., Gagnon, F., Truchon, K., Bastien, M., Picard, F.J., van Belkum, A., Ouellette, M., Roy, P.H., Bergeron, M.G., 2004. New real-time PCR assay for rapid detection of methicillin-resistant Staphylococcus aureus directly from specimens containing a mixture of staphylococci. J. Clin. Microbiol. 42 (5), 1875–1884 (May). Paule, S.M., Hacek, D.M., Kufner, B., Truchon, K., Thomson Jr., R.B., Kaul, K.L., Robicsek, A., Peterson, L.R., 2007. Performance of the BD GeneOhm methicillin-resistant Staphylococcus aureus test before and during high-volume clinical use. J. Clin. Microbiol. 45 (9), 2993–2998. Rossney, A.S., Herra, C.M., Brennan, G.I., Morgan, P.M., O'Connell, B., 2008. Evaluation of the Xpert methicillin-resistant Staphylococcus aureus (MRSA) assay using the
U. Eigner et al. / Journal of Microbiological Methods 107 (2014) 71–73 GeneXpert real-time PCR platform for rapid detection of MRSA from screening specimens. J. Clin. Microbiol. 10, 3285–3290. Stürenburg, E., 2009. Rapid detection of methicillin-resistant Staphylococcus aureus directly from clinical samples: methods, effectiveness and cost considerations. GMS Ger. Med. Sci. 7, Doc06.
73
Wolk, D.M., Picton, E., Johnson, D., Davis, T., Pancholi, P., Ginocchio, C.C., Finegold, S., Welch, D.F., de Boer, M., Fuller, D., Solomon, M.C., Rogers, B., Mehta, M.S., Peterson, L.R., 2009. Multicenter evaluation of the Cepheid Xpert methicillin-resistant Staphylococcus aureus (MRSA) test as a rapid screening method for detection of MRSA in nares. J. Clin. Microbiol. 47, 758–764.
Contents lists available at ScienceDirect
Journal of Microbiological Methods journal homepage: www.elsevier.com/locate/jmicmeth
Note
Validation of the FluoroType® MRSA assay for the rapid identification of methicillin-resistant Staphylococcus aureus directly from patient material Ulrich Eigner ⁎, Anke Veldenzer, Martin Holfelder Limbach Laboratory, Heidelberg, Germany
a r t i c l e
i n f o
Article history: Received 10 July 2014 Received in revised form 15 August 2014 Accepted 16 August 2014 Available online 2 September 2014
a b s t r a c t We performed the first evaluation study of the new HyBeacon based FluoroType® MRSA assay for the detection of MRSA directly from 617 patient specimens. Using culture as the reference method sensitivity and specificity were higher than 95%. Results were available within 2.5 h, including DNA extraction. © 2014 Elsevier B.V. All rights reserved.
Keywords: MRSA PCR Validation Rapid test Staphylococcus aureus
PCR-based rapid tests have been established as an important tool for effective and fast MRSA management. There are several detection formats available like line probe assays, lateral flow dip-sticks, and real-time PCR using fluorescence detection techniques (Stürenburg, 2009; Dalpke et al., 2012; Eigner et al., 2012; Holfelder et al., 2006; Huh et al., 2012; Paule et al., 2007; Rossney et al., 2008; Wolk et al., 2009). In diagnostic laboratory routine PCR tests require high reliability, short time-to-result, easy handling and cost-efficiency. According to this topic, we tested the performance of the new FluoroType® MRSA assay (Hain Lifescience, Germany) for the detection of MRSA directly from patient material. The FluoroType® MRSA test is based on the HyBeacon fluorescence technology (French et al., 2001). HyBeacon probes are single-stranded oligonucleotides labelled with fluorescent dyes. In the single stranded HyBeacon oligonucleotide emission of the fluorescent dyes is inhibited by neighbouring nucleosides. Hybridisation of the HyBeacon probe to a complementary target sequence leads to an increase in fluorescence due to separation of the fluorophores from the vicinity of the nucleosides (French et al., 2001). The FluoroType® MRSA test is performed on the FluoroCycler (Hain Lifescience). The new PCR-test was compared to our established diagnostic procedure. The study was divided into two parts. In the first part of the study, swab specimens of patients who showed no MRSA colonisation or infection in anamnesis were randomly collected in two hospitals in Heidelberg (Agaplesion Bethanien Hospital; St. Vincentius Hospital). The study has been approved by the responsible ⁎ Corresponding author at: Labor Limbach, Im Breitspiel 15, 69126 Heidelberg, Germany. Tel.: +49 6221 3432 192; fax: +49 6221 3432 212. E-mail address: [email protected] (U. Eigner).
http://dx.doi.org/10.1016/j.mimet.2014.08.007 0167-7012/© 2014 Elsevier B.V. All rights reserved.
ethic committee (State Medical Chamber, Baden-Wuerttemberg, Germany, 2011-09-13). The second part of the study comprised specimens from hospitals and medical practices that were sent to our routine laboratory for bacteriological testing. The FluoroType® MRSA assay results were compared to cultural findings. Specimens comprised swabs from nose, throat, skin, and wound and other specimens. For collection and transport of the specimens, swabs with Amies gel medium (with and without charcoal) or liquid Stuart medium were used (all from Copan, Italy). For the FluoroType® MRSA test, the swab was first inoculated in SpheroLyse® suspension, provided with the assay, and then used for inoculation of CHROMagar MRSA (Becton Dickinson, Heidelberg, Germany), CNA agar and thioglycollate broth (Becton Dickinson). The CHROMagar MRSA and the CNA agar plate were incubated at 35 °C for 48 h and evaluated after 24 h and 48 h. The thioglycollate broth was incubated for 24 h and then inoculated on CNA agar and CHROMagar for each specimen. Staphylococcus aureus-colonies were identified by MALDI Biotyper (Bruker Daltonics, Bremen). MRSA detection from cultured MRSA colonies was realized by a PCR-based assay (GenoType MRSA, Hain Lifescience) detecting the mecA gene and S. aureus specific DNA structures. The performance of the FluoroType® MRSA was assessed in comparison to culture by calculation of sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV). In total, 405 specimens were collected for the prospective study part. All of the 15 culturepositive specimens were correctly detected by FluoroType® MRSA. No false-negative results were observed. Of 389 culture-negative specimens the FluoroType® MRSA showed negative results for 386 specimens. 3 culture-negative specimens were tested positive by FluoroType® MRSA.
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U. Eigner et al. / Journal of Microbiological Methods 107 (2014) 71–73
Table 1 Performance of the FluoroType® MRSA assay compared to culture (n = 404 specimens, randomly collected in two hospitals). FluoroType® MRSA
Culture positive (n) Culture negative (n)
Compared to culture
Positive (n)
Negative (n)
Sensitivity (%)
Specificity (%)
PPV (%)
NPV (%)
15 3
0 386
100
99.2
83.3
100
Table 2 Performance of the FluoroType® MRSA assay compared to culture (n = 212 specimens, collected in the routine laboratory). FluoroType® MRSA
True-positive (n) True-negative (n)
Compared to true-positive/true-negative results
Positive (n)
Negative (n)
Sensitivity (%)
Specificity (%)
PPV (%)
NPV (%)
82 5
0 125
100
96.1
94.2
100
One specimen showed inhibition with the FluoroType® MRSA test and was therefore evaluated as an invalid result. The specimen originated from a decubitus wound of a patient who was not treated with antibiotics and who showed no MRSA colonisation or infection in anamnesis. This corresponds to an inhibition rate of 0.25% for FluoroType® MRSA. For the retrospective study part 212 specimens were tested in total. All 82 culture-positive specimens were tested positive by the FluoroType® MRSA test. 125 culture-negative specimens were congruent negative with the PCR test. For 5 culture-negative specimens FluoroType® MRSA showed a positive result. The performance data of the FluoroType® MRSA assay are also shown in Tables 1 and 2. Sensitivity and specificity as well as NPV and PPV of the FluoroType® MRSA assay were comparable to other assays targeting the regions of the open reading frame orfX and the staphylococcal cassette chromosome (SCCmec), namely the real-time PCR assays BD GeneOhm MRSA, BD MAX MRSA (both BD Diagnostics, Sparks, MD), and GeneXpert MRSA (Cepheid, Sunnyvale, CA, USA), and the LightCycler MRSA advanced test (Roche Diagnostics, Mannheim, Germany) (Dalpke et al., 2012; Huh et al., 2012; Paule et al., 2007; Rossney et al., 2008; Wolk et al., 2009). In these publications culture was also the method of comparison. The mean sensitivity of all tests was N 90% and the NPV N95%. For the Xpert MRSA assay sensitivity was reduced for throat specimens (75%) (Rossney et al., 2008). One author also reported a lower sensitivity of the PCR tests (b 90%) when compared to the highly sensitive broth enrichment culture (Wolk et al., 2009). The sensitivity of the FluoroType MRSA test was not influenced by these parameters. As discussed previously for other PCR assays (Dalpke et al., 2012; Eigner et al., 2012; Holfelder et al., 2006; Huh et al., 2012; Paule et al., 2007; Rossney et al., 2008; Wolk et al., 2009), there are several circumstances that can lead to PCR-positive/culture-negative results and results which lead to a decreased PPV. These include strains with SCCmec lacking a functional mecA gene (mecA-drop-out strains) (Donnio et al., 2005), presence of nonviable or non-cultivatable MRSA load (Huletsky et al., 2004), a higher sensitivity of PCR compared to culture (Rossney et al., 2008) or bacterial loads near the detection limit yielding inconsistent results upon repeated testing. One of these reasons might explain the false-positive specimens with the FluoroType® MRSA. In contrast to the studies of Paule et al. (2007) and Rossney et al. (2008), the results of this study were not amended by including patients' MRSA history or other clinical findings. The turnaround time of the FluoroType® MRSA assay is approximately 30 min for sample setup and DNA isolation and about 2 h for amplification and detection and therefore comparable to other rapid MRSA-PCR assays (Hombach et al., 2010). The SpheroLyse DNA isolation kit was easy to handle and released a reliable quantity and quality of DNA for PCR amplification. Growth of MRSA on the selective agar- and broth media was not inhibited after elution of the swabs in SpheroLyse suspension (pre-validation, data not shown). The ready-for-use amplification
premixes enabled convenient handling of the reagents and manual hands-on time was reduced to 10 min. The results of the FluoroType® MRSA-PCR assay were analysed automatically by the test-specific software. We conclude that the FluoroType® MRSA assay shows rapid, sensitive and specific performance results for the direct detection of MRSA in clinical swab specimens. Acknowledgements We thank Ulrike Betz for her excellent technical support. We thank Dr. Christine Wittmann-Jennwein (Agaplesion Bethanien Hospital, Heidelberg) and Dr. Peter Stiefel and Renate Billmaier (St. Vincentius Hospital, Heidelberg) for their continuous collaboration. PCR kits were supplied by Hain Lifescience. U.E. and M.H. have received speaker's honorarium from Hain Lifescience. We declare no conflict of interest. References Dalpke, A.H., Hofko, M., Zimmermann, S., 2012. Comparison of the BD Max methicillinresistant Staphylococcus aureus (MRSA) assay and the BD GeneOhm MRSA achromopeptidase assay with direct- and enriched-culture techniques using clinical specimens for detection of MRSA. J. Clin. Microbiol. 50 (10), 3365–3367 (Oct). Donnio, P.Y., Oliveira, D.C., Faria, N.A., Wilhelm, N., Le Coustumier, A., de Lencastre, H., 2005. Partial excision of the chromosomal cassette containing the methicillin resistance determinant results in methicillin-susceptible Staphylococcus aureus. J. Clin. Microbiol. 43 (8), 4191–4193 (Aug). Eigner, U., Veldenzer, A., Fahr, A.M., Holfelder, M., 2012. Retrospective evaluation of a PCR based assay for the direct detection of methicillin-resistant Staphylococcus aureus in clinical specimen. Clin. Lab. 58 (11–12), 1319–1321. French, D.J., Archard, C.L., Brown, T., McDowell, D.G., 2001. HyBeacon probes: a new tool for DNA sequence detection and allele discrimination. Mol. Cell. Probes 15, 363–374. Holfelder, M., Eigner, U., Turnwald, A.M., Witte, W., Weizenegger, M., Fahr, A., 2006. Direct detection of methicillin-resistant Staphylococcus aureus in clinical specimens by a nucleic acid-based hybridisation assay. Clin. Microbiol. Infect. 12 (12), 1163–1167 (Dec). Hombach, M., Pfyffer, G.E., Roos, M., Lucke, K., 2010. Detection of methicillin-resistant Staphylococcus aureus (MRSA) in specimens from various body sites: performance characteristics of the BD GeneOhm MRSA assay, the Xpert MRSA assay, and brothenriched culture in an area with a low prevalence of MRSA infections. J. Clin. Microbiol. 48 (11), 3882–3887 (Nov). Huh, H.J., Kim, E.S., Chae, S.L., 2012. Methicillin-resistant Staphylococcus aureus in nasal surveillance swabs at an intensive care unit: an evaluation of the LightCycler MRSA advanced test. Ann. Lab. Med. 32 (6), 407–412 (Nov). Huletsky, A., Giroux, R., Rossbach, V., Gagnon, M., Vaillancourt, M., Bernier, M., Gagnon, F., Truchon, K., Bastien, M., Picard, F.J., van Belkum, A., Ouellette, M., Roy, P.H., Bergeron, M.G., 2004. New real-time PCR assay for rapid detection of methicillin-resistant Staphylococcus aureus directly from specimens containing a mixture of staphylococci. J. Clin. Microbiol. 42 (5), 1875–1884 (May). Paule, S.M., Hacek, D.M., Kufner, B., Truchon, K., Thomson Jr., R.B., Kaul, K.L., Robicsek, A., Peterson, L.R., 2007. Performance of the BD GeneOhm methicillin-resistant Staphylococcus aureus test before and during high-volume clinical use. J. Clin. Microbiol. 45 (9), 2993–2998. Rossney, A.S., Herra, C.M., Brennan, G.I., Morgan, P.M., O'Connell, B., 2008. Evaluation of the Xpert methicillin-resistant Staphylococcus aureus (MRSA) assay using the
U. Eigner et al. / Journal of Microbiological Methods 107 (2014) 71–73 GeneXpert real-time PCR platform for rapid detection of MRSA from screening specimens. J. Clin. Microbiol. 10, 3285–3290. Stürenburg, E., 2009. Rapid detection of methicillin-resistant Staphylococcus aureus directly from clinical samples: methods, effectiveness and cost considerations. GMS Ger. Med. Sci. 7, Doc06.
73
Wolk, D.M., Picton, E., Johnson, D., Davis, T., Pancholi, P., Ginocchio, C.C., Finegold, S., Welch, D.F., de Boer, M., Fuller, D., Solomon, M.C., Rogers, B., Mehta, M.S., Peterson, L.R., 2009. Multicenter evaluation of the Cepheid Xpert methicillin-resistant Staphylococcus aureus (MRSA) test as a rapid screening method for detection of MRSA in nares. J. Clin. Microbiol. 47, 758–764.