Why choose our test?

The GenomEra^® MRSA/SA AC Assay Kit offers a rapid and simple high-performance molecular assay for diagnosing methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-susceptible S. aureus (SA or MSSA) infection from positive blood cultures, liquid cultures, or culture plates. The GenomEra MRSA/SA AC Assay Kit enables a definitive differentiation of MRSA or SA in less than one hour as compared to hours or even days spent with conventional identification methods.

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 acquire resistance to antibiotics by the acquisition of exogenous genes such as the mecA and mecC. 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.

For bloodstream infections, both MRSA and SA are amongst the most common causative agents and associated with high morbidity and mortality.³ The immune response to bacteremia can cause sepsis and septic shock, which result in a high rate of mortality despite intensive care— reliable results are thus needed fast. Culture remains the widely used method for screening but requires confirmation by other methods.

Due to the constant evolution of MRSA⁴, it has also become increasingly important that molecular tests are able to detect different strains and manifestations of novel genotypes. One of the most significant variations is a divergent mecA gene, designated mecC.⁵ The GenomEra MRSA/SA AC Assay Kit detects both mecA and mecC genes, ensuring comprehensive coverage of MRSA strains.

Key facts

• Definitive genetic diagnosis of methicillin-susceptible and methicillin-resistant Staphylococcus aureus (SA and MRSA, respectively) with the detection of species-specific gene and mecA and mecC resistance gene markers.
• Contamination-free sample handling with a brief sample preparation—just a simple dilution of a droplet of blood or a colony
• Rapid turnaround time of 50 minutes for 1-4 samples

Assay principle

The GenomEra MRSA/SA AC Assay Kit is a qualitative polymerase chain reaction (PCR) test intended for the detection of MRSA and SA DNA target sequences from positive blood cultures, other microbial liquid cultures that are determined as gram-positive cocci by Gram staining, and culture plates. The test utilizes automated end-point PCR with the GenomEra® CDX instrument to detect a highly conserved nucleic acid sequence specific for SA and the genes encoding for methicillin resistance (mecA and mecC), ensuring comprehensive coverage of the various SA and MRSA strains.

Simple sample preparation and rapid turnaround time make the GenomEra MRSA/SA AC Assay Kit a powerful tool for clinical diagnostics where time is of the essence. The assay has a very simple sample preparation process and yields reliable results in less than one hour. Pre-loaded and sealed test chips allow for easy testing, contamination-free environment, and safe waste disposal.

For positive blood culture or other microbial liquid culture specimens, the GenomEra MRSA/SA AC assay is indicated for use in conjunction with other laboratory tests and clinical data available to the clinician as an aid in the detection of MRSA/SA. Sub-culturing of positive blood cultures is necessary to recover organisms for susceptibility testing or for epidemiological typing. The GenomEra MRSA/SA AC assay is not intended to monitor treatment for MRSA/SA infections.

Clinical performance

In a study by the Robert Koch institute, the GenomEra MRSA/SA AC Assay correctly identified all evaluated strains: 26 mecC-MRSA, 23 mecA-MRSA, and 4 SA strains. The GenomEra MRSA/SA AC Assay was also shown to have an unrivaled clinical performance in blood cultures in a study consisting of 232 samples from a Finnish university hospital (Table 1). The reference methods used were MALDI-TOF for species identification, and minimum inhibitory concentration (MIC) tests for oxacillin (E-tests), standardized single disk tests for other antibiotics, and/or resistance STAM-panel by VITEK 2 for antibiotic susceptibility testing.

Table 1. The GenomEra MRSA/SA AC Assay showed exceptional sensitivity and specificity in a clinical study, with an inhibition rate of 0.86% (2/232). CI, confidence interval; MRSA, methicillin-resistant Staphylococcus aureus; SA, Staphylococcus aureus; NPV, negative predictive value; PPV, positive predictive value.

Sample size (n)	Sensitivity (%) (CI 95%)	Specificity (%) (CI 95%)	PPV (%)	NPV (%)
232	100 (96.34–100)	100 (97.11 –100)	100	100

 

Ordering information

To place an order, please contact your local distributor. 

Product name	Product code
GenomEra MRSA/SA AC Assay Kit
20 tests	CDX-30-05-20
40 tests	CDX-30-05-40
GenomEra CDX System	CDX-10-020

 

The GenomEra MRSA/SA AC 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 manufactured 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.
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. Pien BC, Sundaram P, Raoof N, Costa SF, Mirrett S, Woods CW, Reller LB, Weinstein MP. The clinical and prognostic importance of positive blood cultures in adults. Am J Med 2010;123:819–28.
4. 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.
5. García-Álvarez L, Holden MT, Lindsay H, Webb CR, Brown DF, Curran MD, Walpole E, Brooks K, Pickard DJ, Teale C, Parkhill J, Bentley SD, Edwards GF, Girvan EK, Kearns AM, Pichon B, Hill RL, Larsen AR, Skov RL, Peacock SJ, Maskell DJ, Holmes MA. Meticillin-resistant Staphylococcus aureus with a novel mecA homologue in human and bovine populations in the UK and Denmark: a descriptive study. Lancet Infect Dis 2011;11:595–603.

Additional literature

1. Romero-Gómez MP, Mora-Rillo M, Lázaro-Perona F, Gómez-Gil MR, Mingorance J. Bacteraemia due to meticillin-resistant Staphylococcus aureus carrying the mecC gene in a patient with urothelial carcinoma. J Med Microbiol 2013;62:1914-6.
2. Hirvonen JJ, Kaukoranta S-S. GenomEra MRSA/SA, a fully automated homogeneous PCR assay for rapid detection of Staphylococcus aureus and the marker of methicillin resistance in various sample matrixes. Expert Rev Mol Diagn 2013; 13:655-65.
3. Hirvonen JJ, von Lode P, Nevalainen M, Rantakokko-Jalava K, Kaukoranta S-S. One-step sample preparation of positive blood cultures for the direct detection of methicillin-sensitive and -resistant Staphylococcus aureus and methicillin-resistant coagulase-negative staphylococci within one hour using the automated GenomEra CDX™ PCR system. Eur J Clin Microbiol Infect Dis 2012;31:2835-42.
4. Hirvonen JJ, Nevalainen M, Tissari P, Salmenlinna S, Rantakokko-Jalava K, Kaukoranta S-S. Rapid confirmation of suspected methicillin-resistant Staphylococcus aureus colonies on chromogenic agars by a new commercial PCR assay, the GenomEra MRSA/SA Diagnose. Eur J Clin Microbiol Infect Dis 2012;31:1961-8.