Recognizing Group A β-Hemolytic Streptococcus Bacteria That Cause Strep Throat: Symptoms, Diagnosis, and Treatment
Pharyngitis is an illness caused by infection with Group A β-hemolytic Streptococcus (GABHS), commonly known as strep throat. Group A Streptococcus (GAS) belongs to the species Streptococcus pyogenes, a gram-positive bacterium with a chain-like morphology. GAS is widespread in nature and can adapt to the human body.
This bacterium is known to infect the upper respiratory tract and human skin. Individuals infected with GAS may face high mortality rates. Each year, there are over 616 million new cases of strep throat worldwide. In the United States, this bacterium infects 5–15% of adults and 15–35% of children. Symptoms of GABHS include sore throat, fever, headache, and chills. Other symptoms may include abdominal pain, nausea, and vomiting.
People with strep throat usually do not have a cough, runny nose, or conjunctivitis. In fact, symptoms can become more severe if left untreated, potentially leading to acute rheumatic fever, rheumatic heart disease, bacteremia, peritonsillar abscesses, and more. GABHS transmission occurs through contact with respiratory secretions from an infected person. Once a person is infected, the bacteria incubate in the body for 2–5 days. To prevent and manage this disease, let's take a look at the diagnostic methods, clinical guidelines, and use of antibacterial treatments.
Diagnostic Methods for Strep Throat
Symptoms of GABHS can sometimes resemble those caused by non-GABHS pathogens and viruses responsible for acute pharyngitis. Therefore, a highly accurate physical examination and a thorough review of the patient's medical history are crucial in diagnosing GABHS. There are five diagnostic methods that can be used to accurately detect GABHS infection: clinical scoring systems, rapid antigen detection tests (RADT), throat cultures, and nucleic acid amplification tests (NAAT).
The clinical scoring system uses clinical symptoms such as fever, sore throat, and absence of cough to calculate a risk score. The RADT is a quick and easy diagnostic method that uses a throat swab to collect a sample, which is then tested for the presence of specific GABHS antigens. Throat cultures involve swabbing the pharynx and tonsils and culturing the sample on 5% sheep blood agar. Bacterial identification is done through colony morphology, Gram staining, and serogrouping. NAAT works by detecting specific GABHS genes through DNA amplification.
Treatment and Prevention of GABHS
To relieve GABHS symptoms, medications such as acetaminophen or paracetamol can be used. Treatment may also include narrow-spectrum antibiotics, such as penicillin V, typically administered over a 10-day course. Alternative antibiotics for patients allergic to penicillin include amoxicillin, azithromycin, cephalosporins, and clarithromycin. To date, the GABHS-causing bacteria have not shown resistance to penicillin. However, the use of antibiotics should be considered carefully due to concerns over antibiotic resistance in Streptococcus pyogenes.
Infection by S. pyogenes can be prevented by practicing good hand hygiene with antiseptics. Although there is currently no specific vaccine for this bacterial infection, researchers are actively working on developing one. Challenges in vaccine development include the vast strain variability of S. pyogenes in the environment and the need for time and volunteer subjects for trials.
We should not take sore throats lightly, especially when caused by bacterial infections like Streptococcus pyogenes, as they can develop into more serious conditions. Managing such infections requires symptom-based diagnosis, laboratory testing, and appropriate antibiotic selection. Moreover, continuous public education on hygiene and health is essential.
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Author: Safira
Editor: Sabilla Reza
Reference:
Mustafa, Z., & Ghaffari, M. (2020). Diagnostic methods, clinical guidelines, and antibiotic treatment for Group A streptococcal pharyngitis: A narrative review. Frontiers in Cellular and Infection Microbiology, 10, 563627. https://doi.org/10.3389/fcimb.2020.563627
Newberger R, Hollingshead CM. Group A Streptococcal Infections. [Updated 2025 Jan 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559240/
