Strep A Identification Image

Strep A Identification – Product Availability

As many of you will have noted, there has been a number of reports in the news regarding invasive Group A Streptococcus (GAS) infection in children under 10 years old, with the death toll sadly reaching nine children to date.

UK Health Security Agency (UKHSA) has published a blog page providing information and guidance to the general public.

Streptococcus pyogenes (Group A Streptococcus or GAS)

Colonial Appearance on 5% Blood Agar: Greyish white, transparent to translucent, matt or glossy, large zone of beta haemolysis.

GAS is directly responsible for a variety of inflammatory and suppurative conditions e.g. sore throats, scarlet fever, cellulitis, impetigo, puerperal sepsis, otitis media, septicaemia and wound infections, and can also be indirectly associated with rheumatic fever and glomerulonephritis. However, infection with GAS is rarely serious and can be treated with antibiotics. The organism is found in the throat or nasal cavity and can be transmitted by close contact with an infected person through coughs and sneezes or from a wound. It can also be found in a proportion of asymptomatic people.

Invasive GAS (iGAS) infection is when the organism enters the bloodstream or lungs and can cause more serious conditions such as necrotising fasciitis, necrotising pneumonia, sepsis, and Streptococcal Toxic Shock Syndrome.

Pro-lab Diagnostics offers a range of products for the identification of Group A Streptococcus in a number of formats.

Prolex™  – Rapid Latex Agglutination

Pro-Lab Diagnostics has been the market leader in the UK for many years with the Prolex™ Streptococcal latex agglutination kit, providing Lancefield classification from direct colonial growth. Click here to view all products available from the Prolex™ range.

Viasure – Real Time PCR

Viasure Real-Time PCR kit is available for the detection of GAS from pharyngeal and otic exudate swabs from patients with signs and symptoms of respiratory infection, and has a limit of detection of ≥2 copies/µL.

All Viasure® kits have the same workflow and hands-on preparation, allowing easy adoption of new assays.

CodeDescriptionKit Size
VS-GAS196TVIASURE RT-PCR Streptococcus Group A96

Viasure Product Features

  • Room temperature storage and shipping
  • Lyophilised ready-to-use format; only need to add buffer and extracted sample
  • Two-year shelf life
  • Ability to pool mastermix to minimise waste
  • Validated with almost all extraction systems and cyclers as well as liquid handling platforms for high throughput automation

Viasure DNA/RNA Pathogen Extraction Kit

Total nucleic acid extraction from various biological samples: swabs, saliva, sputum, bronchoalveolar lavages, faecal and urine samples. Based on magnetic particles, which allows automation for high throughput analysis, reducing hands-on-time and improving reproducibility. The extraction kit has been optimized for two types of magnetic separation methods: VIASURE V-Flex and KingFisher® Flex (other platforms ongoing).

CodeDescriptionKit Size
VS-EAP0196OPVIASURE DNA/RNA Pathogens Extraction Kit96

Proflow™ Strep A

The Proflow™ Streptococcus A test is a single use rapid membrane immunoassay for the qualitative detection of Group A Streptococcus antigen in human throat swab samples or GAS colonies recovered from culture.

Monoclonal antibodies to Streptococcus A antigen are coated onto the test line region of the strip. During testing the sample migrates along the membrane by capillary action and is allowed to react with the conjugate on the test strip.

In the case of a positive result the specific antibodies present on the membrane will capture the coloured conjugate. A blue line should always appear in the control line region to show that sufficient volume was added, proper flow was obtained and the reagents functioned

correctly. Failure of the control line to appear, whether or not test lines are present, indicates an invalid assay.

The test is interpreted by the presence or absence of visibly detectable coloured lines in the test region at 10 minutes or less depending on the concentration of antigen present. A positive result will show a pink/red test line and a blue control line, indicating that Streptococcus A antigen is present in the sample. A negative test result, read at 10 minutes, will show only a blue control line, indicating that Streptococcus A antigen was not detectable in the sample.


Pro-Cult® discs are manufactured exclusively from NCTC® (National Collection of Type Cultures) and NCPF® (National Collection of Pathogenic Fungi) cultures and are guaranteed to be first generation from the source strains.  NCTC®, NCPF® and National Collection of Type Cultures are trademarks of UKHSA.  Equivalent ATCC® strains are listed where available.  ATCC® is registered trade mark of the American Type Culture Collection.

Each Pro-Cult® disc is a freeze-dried presentation of approximately 10⁶ – 10⁹ viable organisms.  Unlike many other cultures, Pro-Cult® discs are sourced from recognised culture collections; each lot number of Pro-Cult® is guaranteed as “first generation” directly traceable to its source.

The unique manufacturing process uses the parent strain suspended in an inert medium which is then freeze dried immediately into the presentation format.  When the strains are then reconstituted in your laboratory, for the first time, you have the guaranteed first generation. All QC testing is done in the same way that the customers reconstitute the strain to guarantee first generation in accordance with ISO 13485:2016 in a UKAS accredited laboratory (No.2496), certificates are available on request.

Streptococcus agalactiae:  

PLD.16 NCTC®8181/ATCC®13813.Type strain, used for QC. UKHSA recommended negative control for aesculin test. Colonies are entire, glistening, circular, smooth and slightly convex and opaque.

Streptococcus pneumoniae:

PLD.95 NCTC®12977/ATCC®49619. Has low-level, but clinically relevant, resistance to penicillin – the BSAC methodology uses this control to assess detection of resistance rather than sensitivity. UKHSA recommended positive control for bile solubility test. CLSI, BSAC, EUCAST recommended control strain for susceptibility testing.

Streptococcus pneumoniae:

PLD.19 NCTC®12695/ATCC®6303. Fully sensitive. Colonies are mucoid, entire, smooth and alpha-haemolytic, a few  colonies may have an irregular edge.

Streptococcus pyogenes:  

PLD.20 NCTC®12696/ATCC®19615. Used for QC and media testing. Lancefield group A, beta-haemolytic.

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