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Group A Streptococcus (GAS) Essay

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Streptococcus pyogenes, also known as Group A streptococcus (GAS), is a β-hemolytic, Gram-positive bacterium that most commonly causes respiratory disease, including pharyngitis or tonsillitis, as well as skin infections such as impetigo and cellulitis. The organism is transmitted via respiratory droplets or by contact with fomites, and commonly infects young children. In addition to the common clinical presentations associated with S. pyogenes, some individuals develop the postinfectious sequelae of rheumatic fever and glomerulonephritis. Due to the severity of these medical consequences, prophylactic antibiotic use is often recommended for any patients with otherwise mild S. pyogenes infections (21).
In addition to its traditional
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Antibiotic use, particularly with clindamycin and linezolid, may be useful in treating GAS-associated necrotizing fasciitis, as they target both M-proteins and exotoxins (5). Some cases have been treated with hyperbaric oxygen therapy, with recent data suggesting prompt surgical therapy instead is vital for preventing amputations (18). Even after treatment, however, necrotizing fasciitis mortality has been estimated to range from 24%-60% (10).
In S. pyogenes-associated necrotizing fasciitis, the bacteria first invade host fascia before spreading and causing more invasive damage. Initial GAS invasion can occur through three primary pathways: 1) preceding superficial infection; 2) direct inoculation; or 3) hematogenous seeding from a previous injury site. After colonization, GAS spread through the typically sterile fascial planes that separate muscle groups, which are only loosely held together by connective tissue. The streptococci then release several proteases and other virulence factors that cause localized tissue damage. Simultaneously, this dissemination prompts the arrival of acute inflammatory host cells; the response of polymorphouclear leukocytes (PMNs), in particular, can also contribute to the tissue damage characteristic of necrotizing fasciitis. Once the
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