Group A streptococcal infection
Group A streptococcal infection is caused by the bacterium Streptococcus pyogenes and can lead to various contagious illnesses, with strep throat being the most common form. Other manifestations of this infection include impetigo, a superficial skin infection, as well as more serious conditions like deep tissue infections and bacteremia. The bacteria are often found in the throat and on the skin, particularly during peak seasons in fall and spring, and can spread through respiratory droplets or direct contact. Those at higher risk for group A strep infections include children, individuals with weakened immune systems, and those in crowded environments.
Symptoms of strep throat typically involve fever, sore throat, and swollen lymph nodes, while other infections may present with localized redness and swelling. Diagnosis can be made through laboratory tests or clinical examination based on symptoms. Treatment usually involves antibiotics, such as penicillin, to reduce symptom duration and prevent complications, which can include rheumatic fever and toxic shock syndrome. Preventive measures focus on minimizing transmission through good hygiene practices, including frequent handwashing and wearing masks in high-risk settings. Despite advancements in treatment, rates of group A streptococcal infections have recently reached historical highs.
Group A streptococcal infection
- ANATOMY OR SYSTEM AFFECTED: Skin, throat, tissue, tonsils
- ALSO KNOWN AS: Group A strep, Streptococcus pyogenes infection
Definition
A group A streptococcal infection includes contagious illnesses caused by the bacterium Streptococcus pyogenes. The most common group A infection is strep throat. Other group A infections include impetigo (superficial skin infection) and serious deep tissue and blood infections. In rare cases, infection with group A strep can result in complications such as rheumatic fever, post-strep glomerulonephritis (kidney inflammation), and toxic shock syndrome.
Causes
S. pyogenes bacteria are commonly found in the throat and on the skin. During peak times between fall and spring, up to 20 percent of school-age children may carry the bacteria and may transmit it without becoming ill. The organism is spread between people through respiratory droplets or direct contact. Infected persons are contagious as long as they have symptoms. Infections that go untreated with antibiotics may be contagious beyond the symptomatic period.
While most cases of pharyngitis (strep throat) are viral, group A strep is the most common bacterial cause. Virulence factors of the bacterial cell influence the severity of the disease.
Risk Factors
Several factors increase the risk of developing a localized group A strep infection like strep throat and impetigoage (children of all ages), time of year (between fall and spring), exposure to school-age children, crowded settings, chronic illness, or having a weakened immune system. Also, having a past history of group A strep infection may predispose one to future infection.
The risk of more severe invasive disease is increased by chickenpox infection, other infections of the skin, and immunosuppression of any cause. Infection with group A strep carries a risk of complications that include rheumatic fever, post-strep glomerulonephritis, and streptococcal toxic shock syndrome (STSS).
Symptoms
Symptoms of strep throat include fever, sore throat, and swollen lymph nodes, sometimes accompanied by headache, skin rash, and vomiting. Redness, swelling, and pus may be present on the tonsils.
Symptoms of infection elsewhere depend on the area of the body, but usually include redness, inflammation, and swelling accompanied by fever. Symptoms of bacteremia (bacterial blood infection) often include fever and shaking chills.
Screening and Diagnosis
Diagnosis of strep throat may be made by laboratory test (rapid antigen test or throat culture) but often is made clinically if the signs and symptoms point to infection. The absence of typical viral symptoms, such as runny nose and cough, may indicate strep.
Group A strep infection is suspected when redness, inflammation, and swelling are present in an area that is a common location for that type of infection. A blood culture is required for the diagnosis of strep bacteremia. Occasionally, a diagnosis is made following the appearance of one of the complications of strep infection, such as post-strep glomerulonephritis.
Treatment and Therapy
When a diagnosis of strep infection is confirmed or strongly suspected, antibiotic treatment is indicated to shorten the duration of symptoms, to shorten the time of contagiousness, and to prevent complications. Penicillin is effective when administered orally or by injection. Other antibiotics, like amoxicillin, erythromycin, azithromycin, and clindamycin, are used for persons allergic to penicillin. While these medications have largely controlled the spread of group A streptococcal infections, rates of infection in 2023 reached a twenty-year-high.
Prevention and Outcomes
Prevention involves minimizing the spread of bacteria. Frequent handwashing for at least twenty seconds, covering one's mouth when coughing, careful personal hygiene, wearing a well-fitting mask in settings that predispose an individual to group A strep, and avoiding the respiratory secretions of others help to prevent transmission.
Bibliography
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