MRSA/SA Multi Swab

Highly sensitive assay for ruling out MRSA/SA carriage

Why choose our test?

The GenomEra® MRSA/SA Multi Swab Assay Kit offers a rapid and simple high-performance molecular assay for the direct detection of methicillin-susceptible and methicillin-resistant Staphylococcus aureus (SA and MRSA, respectively) infection from clinical swab samples. The GenomEra MRSA/SA Multi Swab Assay Kit is the first molecular assay validated for pooled swab specimens in liquid transport medium. The test combines swabs from the three most potential MRSA carriage sites—nose, throat, and groins.

The GenomEra MRSA/SA Multi Swab Assay Kit, utilizing pooled specimens from three different sampling sites and highly sensitive molecular testing with conserved genomic targets, provides the most sensitive approach for MRSA and SA screening. The test can reliably rule out MRSA/SA infection providing results in less than one hour. In case of a positive PCR result, the same sample can be used for confirmation by culture.

SA infections range from minor skin infections to life-threatening diseases such as pneumonia, meningitis, osteomyelitis, endocarditis, and bacteremia. SA is known for its capability to rapidly acquire resistance to antibiotics by the acquisition of an exogenous gene such as the mecA. MRSA is the most commonly identified antibiotic-resistant nosocomial pathogen and a significant cause of morbidity, mortality and increased healthcare costs.1 The number of new infections has been increasing for years2, which has led to more active MRSA screening programs worldwide.

Due to the constant evolution of MRSA3, it has also become increasingly important that genetic tests detect different strains and manifestations of novel genotypes to avoid false negative results. The GenomEra MRSA/SA Multi Swab assay relies on dual-target detection, combining the specific and sensitive detection of S. aureus with the detection of the species-specific gene and the mecA gene encoding for methicillin resistance. This strategy allows for comprehensive coverage of the various MRSA strains as well as the detection of methicillin-susceptible SA. The GenomEra MRSA/SA Multi Swab assay relies on dual-target detection: specific and sensitive detection of S. aureus via a species-specific gene target combined with the detection of mecA associated with methicillin resistance.

Key facts

  • Rapid molecular detection of methicillin-susceptible and methicillin-resistant Staphylococcus aureus (SA and MRSA) simultaneously from a pooled swab sample.
  • Highly sensitive PCR diagnostics with very conservative genomic targets of SA and the mecA gene
  • Reliable negative results in less than one hour and the possibility to utilize the same sample for confirmation by culture in case of positive PCR result

Assay principle

The GenomEra MRSA/SA Multi Swab is a qualitative PCR test intended for simultaneous screening of multiple body sites that are most likely to be colonized with MRSA—nose, throat, and groin/perineum. The test utilizes automated end-point PCR on the GenomEra® CDX System to detect a highly conserved nucleic acid sequence specific for SA and the mecA gene encoding for methicillin resistance, ensuring comprehensive coverage of the various SA and MRSA strains.

The clinical sensitivity of MRSA testing is significantly improved by expanding the screening to multiple extra-nasal sites, which has become a common practice in culture-based applications and is here applied in sensitive molecular testing. The GenomEra Multi Swab Assay Kit is also compatible with swabs taken from wounds and other infection foci. The assay accepts direct swab specimens pooled in liquid medium (eSwab™ MRSA Collection System, Copan), and the same medium can be used for confirmation by culture, thus avoiding the need of collecting additional samples. Positive findings are to be confirmed by subsequent microbe culturing, which is also necessary for recovering isolates for susceptibility testing and/or genetic typing.

Easy sample preparation and rapid turnaround time (less than hour) make the GenomEra MRSA/SA Multi Swab Assay Kit a powerful tool for clinical diagnostics where time is of the essence. Pre-loaded and sealed test chips allow for easy testing, contamination-free environment, and safe waste disposal.

Clinical performance

The clinical performance of the GenomEra MRSA/SA Multi Swab was evaluated in a multi-site study carried out at five study centers in Europe (Table 2). A total of 201 samples pooled from the nostrils, throat and groin/perineum were analyzed. The reference methods used were biochemical tests, such as Staphylococcal and S. aureus agglutination tests, catalase tests, detection of deoxyribonuclease activity, API Staph, and VITEK 2 microbial identification, as well as antibiotic susceptibility tests, including Minimum Inhibitory Concentration (MIC) for oxacillin (E-test), standardized single disk tests for other antibiotics, and resistance STAM-panel by VITEK 2.

Table 2. The GenomEra MRSA/SA Multi Swab Assay Kit had an excellent sensitivity and a negative predictive value (NPV) in a clinical evaluation of pooled samples. PPV, positive predictive value.

Sample size MRSA prevalence (%) Sensitivity (%) Specificity (%)* NPV (%) PPV (%)
Long-term care facility and hospitalized patients; n = 83 53.0 100 61.1 100 75.9%
At-risk patients on hospital admission; n = 85 15.3 92.3 85.3 98.3 54.5
Healthy volunteers; n = 33 0 90.9 100 NA
Total; n = 201 28.4 98.2 80.3 99.1 67.5

* In some cases, one or more individual swabs were collected from the same patients. Some of these were MRSA culture-positive, indicating true MRSA colonization. However, the comparison was only performed against cultures of pooled swabs, i.e. using the same sample media for both methods.

Ordering information

To place an order, please contact your local distributor.

Product name Product code
GenomEra MRSA/SA Multi Swab Assay Kit
20 tests CDX-40-01-20
40 tests CDX-40-01-40
GenomEra CDX System CDX-10-020

The GenomEra MRSA/SA Multi Swab Assay Kit has received the European CE marking for In Vitro Diagnostic (IVD) medical devices according to the requirements of EU Directive 98/79/EC (IVDD) and is available in European markets. In other markets, please contact your local distributor for availability. The product is manufacturer by Uniogen, Finland.

References

  1. Hsu LY, Wijaya L, Tan BH. Management of healthcare-associated methicillin-resistant Staphylococcus aureus. Expert Rev Anti Infect Ther 2005;3:893–905. [Review]
  2. Kerttula AM, Lyytikäinen O, Kardén-Lilja M, Ibrahem S, Salmenlinna S, Virolainen A, Vuopio-Varkila J. Nationwide trends in molecular epidemiology of methicillin-resistant Staphylococcus aureus, Finland, 1997-2004. BMC Infect Dis 2007;7:94.
  3. Deurenberg RH, Vink C, Kalenic S, Friedrich AW, Bruggeman CA, Stobberingh EE. The molecular evolution of methicillinresistant Staphylococcus aureus. Clin Microb Infect 2007;13:222–35.

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