Strep A: Is It a Rising Global Threat? How to Use the Strep A Test Kit?
Group A Streptococcus (GAS) is responsible for various infections associated with benign to life-threatening diseases around the world. Although Streptococcus A most commonly causes self-limiting diseases such as strep throat and mild pharyngitis, invasive group A strep (iGAS) infections can lead to severe diseases such as necrotizing fasciitis streptococcal toxic shock syndrome, along with autoimmune conditions such as rheumatic heart disease (RHD). Despite the development of antibiotic treatments against these infections, the recent upsurge in the circulation of Group A Streptococcus has caused significant concern following several deaths among children and other at-risk groups. The latest data by the UK Health Security Agency (UKHSA) demonstrates that at least 19 children have died from a severe form of the infection caused by Streptococcus A (Strep A). Given the unusual surge in notifications of Group A Streptococcus (GAS) and invasive Group A streptococcal infections (iGAS), public health authorities are now urging caution over the signs and symptoms associated with Streptococcus A (Strep A). Read along to learn more about Streptococcus A (Strep A), its symptoms, and its diagnosis.
What is Group A Streptococcus (GAS)?
Group A streptococcal infections are bacterial infections caused by Streptococcus pyogenes. S. pyogenes is a species of beta-hemolytic gram-positive bacteria. Estimated to infect up to 20% of all people worldwide at any given time, Group A Streptococcus (GAS) are common bacteria that are naturally present in the mouth, throat, and respiratory system. They spread through contact with an infected person’s mucus or skin sores. Once the bacteria enter the host’s body, they target the pharyngeal mucosa and/or skin as the primary sites of adherence and colonization. Unless they enter the bloodstream of the host, Group A Streptococcus (GAS) tend to cause mild and self-limiting infections in the pharynx and the skin, such as strep throat, scarlet fever, and impetigo. In fact, group A streptococcal infections are responsible for around 600 million cases of pharyngitis worldwide each year. According to estimations by the World Health Organization (WHO), 111 million children in underdeveloped and developing countries have streptococcal impetigo at any time.
Less commonly, group A streptococcal infections such as pharyngitis and impetigo can trigger certain autoimmune responses involving multiple organ systems, including the heart, joints, and central nervous system. The combination of infection and the resulting autoimmune response may lead to the development of a severe life-threatening disease known as acute rheumatic fever. It is estimated that Group A Streptococcus (GAS) is responsible for around 33 million rheumatic heart disease (RHD) cases, leading to around 300,000 deaths globally.
What is invasive Group A streptococcal infection (iGAS)?
Suppose Group A Streptococcus (GAS) gets past the initial immune defenses of the host. In that case, the bacteria can infiltrate deeper sites of the body that are typically free from these bacteria, such as blood, lungs, and muscles. This leads to a more severe form of infection known as invasive Group A streptococcal infection (iGAS). Invasive Group A streptococcal infections can manifest as any of the various clinical syndromes ranging from pneumonia, abscesses, and meningitis to bacteremia, necrotizing fasciitis, and streptococcal toxic shock syndrome. Necrotizing fasciitis is a potentially fatal skin infection caused by “flesh-eating bacteria”. Streptococcal toxic shock syndrome, on the other hand, refers to a condition involving the malfunction of multiple organ systems due to infection.
Major groups that are at higher risk of developing invasive Group A streptococcal infections (iGAS) include older adults, infants, immunocompromised people, drug users, and those with specific conditions such as cancer, heart disease, diabetes, and HIV. Around 30% of all invasive Group A streptococcal infections (iGAS) result in the patient’s death. Along with rheumatic heart disease (RHD), invasive Group A streptococcal infections (iGAS) cause over 500,000 deaths yearly. These estimations place Group A Streptococcus (GAS) among the top ten worldwide causes of infectious disease mortality.
What are the symptoms of infection with Streptococcus A (Strep A)?
The clinical presentation of group A streptococcal infections (GAS) depends on the sites targeted by the bacteria. If Group A Streptococcus (GAS) causes pharyngitis, common symptoms include sore throat, fever, difficulty swallowing, swollen lymph nodes, fatigue, and general malaise. In the case of scarlet fever, a skin rash may also develop alongside respiratory symptoms. If the bacteria adhere to and colonize the host’s skin, the infection may lead to impetigo, which presents a red rash with fluid-filled blisters, a honey-colored crust on the skin, and itching. Among these infections, streptococcal pharyngitis is commonly observed among people of all ages, whereas scarlet fever and impetigo predominantly affect children.
How to test for Strep A?
The diagnosis of group A streptococcal infections (GAS) may involve throat culture or rapid antigen testing. Alongside laboratory methods such as throat culture, many countries worldwide have also approved rapid antigen testing in the form of lateral flow assays for use in diagnosing strep A. Unlike laboratory methods detecting the presence of bacteria, antigen detection involves the detection of proteins specific to Group A Streptococcus (GAS). These assays’ technology, design, material, and procedure are similar to the lateral flow tests commonly used to diagnose COVID-19.
Assays based on the rapid antigen detection method typically require a medical practitioner’s collection of oropharyngeal swab samples. Following the collection and procession of the oropharyngeal swab samples, these assays deliver qualitative results within 15 minutes. In patients with clinical and epidemiological risk factors of Group A streptococcal infections (GAS), rapid antigen tests, such as our Strep A Rapid Test Kit, offer a rapid, accurate, and convenient method to assist the diagnosis of infections such as scarlet fever, pharyngitis, tonsillitis, and impetigo. These kits typically incorporate labeled antibodies to visualize the result and test validity. The appearance of the control line (C) indicates the validity of the results. In contrast, the appearance of the test line (T) indicates the detection of the bacteria within the collected sample. After receiving a positive result, the patient can safely start a course of antibiotics to treat the detected infection.
REFERENCES
Piper, S. F. (2014). Group A Streptococcal Peptides expressed in HBsAg-S VLPs as a vaccine candidate. University of Southern Queensland.
