GeneXpert® Xpress System Video
Educational Materials
Antibiotic Stewardship in the Emergency Department
This webinar discusses the importance of diligent antimicrobial stewardship and accuracy of diagnostic tests for the detection of Group A Streptococcus pharyngitis. It provides commentary on the high confidence that molecular testing affords the antibiotic steward and how technology can reduce the practice of prescribing antibiotics "just-in-case" there is an infection, especially as testing moves closer to the patient.
Strep A Diagnostics: Advances in Testing to Improve Patient Outcomes
Frequently Asked Questions
The Xpert Xpress Strep A test, performed on the GeneXpert® Instrument Systems, is a rapid, qualitative in vitro diagnostic test for the detection of Streptococcus pyogenes (Group A β-hemolytic Streptococcus, Strep A) in throat swab specimens from patients with signs and symptoms of pharyngitis.
The Xpert Xpress Strep A test can be used as an aid in the diagnosis of Group A Streptococcal pharyngitis. The test is not intended to monitor treatment for Group A Streptococcus infection.
Group A streptococci are gram-positive, beta-hemolytic bacterial pathogens that commonly cause infections in the throat (pharyngitis or “strep throat”) or on the skin (cellulitis and impetigo) and can cause a wide range of other serious infections (e.g., sepsis, pneumonia, and meningitis). If left untreated, mild infections can lead to more serious infections. The most severe but least common forms of invasive Group A streptococcal disease are necrotizing fasciitis and streptococcal toxic shock syndrome (STSS). Untreated post-infection sequelae can also occur (e.g., rheumatic fever).
Pharyngitis may also be caused by other bacteria including Group C/G streptococci, Archanobacterium haemolyticum and viral etiologies, such as common respiratory viruses causing the common cold and EBV (i.e. Mono). Detection and identification of other streptococci and A. haemolyticum requires culture. Detection of viral pharyngitis is often by NAAT or other serological methods (e.g., EBV).
No, Xpert Xpress Strep A test does not require culture confirmation. It is a rapid PCR test for the qualitative detection of Group A streptococci from throat swab specimens without the need for culture confirmation of negative Xpert Xpress Strep A results. For negative samples, the time to result is 24 minutes. For positive samples, the time to result can be as early as 18 minutes.
The Xpert Xpress Strep A has been validated only with throat swabs using Cepheid’s recommended procedure per package insert. (1)
The acceptable collection device is Copan Liquid Amies Elution Swab (ESwab™) Collection and Transport System. The following ESwab collection kits may be used: Copan 480CE, Copan 480C, or Copan 480CFA. (1)
There are two external controls recommended in the IFU from ZeptoMetrix for this test, NATSPY-6MC (Positive Control) and NATSDG-6MC (Negative Control). For appropriately certified labs (e.g. CLIA-certification to perform moderately complex testing), many other vendors offer commercially available alternative quality control materials in addition to the ZeptoMetrix controls listed in the IFU If a laboratory sources alternative materials for external quality control, it is their responsibility to ensure that material performs as expected with the Xpert Xpress Strep A test. External controls should be used in accordance with local and state accrediting organizations, as applicable. (1)
References
1. Xpert® Xpress Strep A Package Insert. 301-6574, Rev. F. Accessed March 10, 2023 https://www.cepheid.com/en-USntent/dam/www-cepheid-com/documents/package-insert-files/Xpert%20Xpress%20Strep%20A%20ENGLISH%20IFU%20301-6574%20Rev%20F.pdf