Group A Streptococcal Infections

Group A  (GAS) refers to the bacterial species "," which is a gram-positive bacterium that grows in pairs and chains. GAS is ubiquitously found in nature and is uniquely adapted to humans. GAS is responsible for a wide range of infections affecting the upper respiratory tract and skin, ranging from mild and superficial to severe and invasive forms (iGAS) (see   Bacterium).  GAS infections are increasing globally, with high morbidity and mortality rates. These infections can affect various areas of the body and can be categorized based on their location and depth. Examples include pharyngitis, scarlet fever, and impetigo (superficial keratin layer); cellulitis (subcutaneous tissue); erysipelas (superficial epidermis); and more severe conditions such as streptococcal toxic shock syndrome (STSS), myositis and myonecrosis (muscle), and necrotizing fasciitis (NF; fascia). In addition to causing infections, GAS can lead to immune-mediated sequelae, including acute rheumatic fever (ARF), post-streptococcal glomerulonephritis (PSGN), and complications from immune-mediated processes, such as rheumatic heart disease (RHD).  Although most cases of pharyngitis are viral, GAS is the leading bacterial cause of acute pharyngitis. GAS accounts for 5% to 15% of sore throat visits in adults and 20% to 30% in children presenting with pharyngitis. Prompt diagnosis and treatment are essential to prevent ARF and other sequelae. Established criteria, diagnostic methods, and guidelines for managing GAS pharyngitis are available that aim to ensure timely diagnosis and reduce the risk of suppurative complications, such as peritonsillar abscess, iGAS infections, nonimmune-mediated sequelae, and further transmission.  Despite the availability of guidelines for diagnosing GAS pharyngitis, antibiotics are often overprescribed, leading to unnecessary exposure and contributing to antibiotic resistance. Antibiotic resistance has been reported in various antibiotics, including penicillin, which is first-line therapy. Overprescription is driven by several factors, such as poor adherence to guidelines, challenges in accurately diagnosing GAS pharyngitis, misdiagnosing GAS carriage as an active infection, and pressure from patients and clinicians to prescribe antibiotics. Clinicians must exercise caution and prescribe antibiotics only when necessary to minimize antibiotic pressure and reduce the risk of resistance development.