“Pathogenesis And Resistance Mechanisms In Group A Streptococcus: A Clinical And Molecular Perspective”

Abstract

Group A Streptococcus (GAS) (Streptococcus pyogenes) is an important human pathogen that causes many life-threatening and non-life-threatening infections. This chain-forming Gram-positive round bacterium is a human-only pathogen, i.e. it does not infect other animal species by nature. GAS colonises the human pharynx and skin and its infectious capacity reflects the combined actions of a number of virulence factors that mediate evasion of the host immune response and tissue injury. As understanding the biology of GAS and the mechanisms of pathogenesis through antibiotic resistance becomes increasingly important for preparedness against newer strains, so too does understanding its health implications for susceptible individuals. The most common infection identified as streptococcal is pharyngitis, also known as strep throat, most common among children age 5-15 yr. It’s marked by a severe sore throat, fever, headache and sometimes swollen lymph nodes in the neck. Although often self-limiting, untreated strep throat can result in serious complications. Acute rheumatic fever (ARF) is one of the most serious, an inflammatory disease that can impact the heart, joints, skin and brain. ARF usually occurs weeks after a GAS pharyngitis and may cause permanent cardiac damage, called rheumatic heart disease (RHD). RHD remains a leading cause of cardiovascular morbidity and mortality in the developing world, and particularly in low- and middle-income countries. The mechanisms for the development of ARF after GAS infection are not completely understood, but it is thought that molecular mimicry is involved, where bacterial antigens are similar enough to host tissues that the immune response affects both. Early diagnosis and appropriate treatment of strep throat with antibiotics is critical in preventing ARF and RHD.