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Streptococcus pyogenes

Streptococcus pyogenes
False-color scanning electron micrograph of chain of Streptococcus pyogenes bacteria (yellow)
Scientific classification Edit this classification
Domain: Bacteria
Phylum: Bacillota
Class: Bacilli
Order: Lactobacillales
Family: Streptococcaceae
Genus: Streptococcus
Species:
S. pyogenes
Binomial name
Streptococcus pyogenes
Rosenbach 1884

Streptococcus pyogenes is a species of Gram-positive, aerotolerant bacteria in the genus Streptococcus. These bacteria are extracellular, and made up of non-motile and non-sporing cocci (round cells) that tend to link in chains. They are clinically important for humans, as they are an infrequent, but usually pathogenic, part of the skin microbiota that can cause group A streptococcal infection. S. pyogenes is the predominant species harboring the Lancefield group A antigen, and is often called group A Streptococcus (GAS). However, both Streptococcus dysgalactiae and the Streptococcus anginosus group can possess group A antigen as well. Group A streptococci, when grown on blood agar, typically produce small (2–3 mm) zones of beta-hemolysis, a complete destruction of red blood cells. The name group A (beta-hemolytic) Streptococcus is thus also used.[1]

The species name is derived from Greek words meaning 'a chain' (streptos) of berries (coccus [Latinized from kokkos]) and pus (pyo)-forming (genes), since a number of infections caused by the bacterium produce pus. The main criterion for differentiation between Staphylococcus spp. and Streptococcus spp. is the catalase test. Staphylococci are catalase positive whereas streptococci are catalase-negative.[2] S. pyogenes can be cultured on fresh blood agar plates. The PYR test allows for the differentiation of Streptococcus pyogenes from other morphologically similar beta-hemolytic streptococci (including S. dysgalactiae subsp. esquismilis) as S. pyogenes will produce a positive test result.[3]

An estimated 700 million GAS infections occur worldwide each year. While the overall mortality rate for these infections is less than 0.1%, over 650,000 of the cases are severe and invasive, and these cases have a mortality rate of 25%.[4] Early recognition and treatment are critical; diagnostic failure can result in sepsis and death.[5][6] S. pyogenes is clinically and historically significant as the cause of scarlet fever, which results from exposure to the species' exotoxin.[7]

  1. ^ "Streptococcus pyogenes - Pathogen Safety Data Sheets". Government of Canada, Public Health Agency of Canada. September 26, 2001.
  2. ^ Ryan KJ, Ray CG, eds. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 978-0-8385-8529-0.
  3. ^ Spellerberg B, Brandt C (October 9, 2022) [Originally published September 15, 2022]. "Chapter 29: Laboratory Diagnosis of Streptococcus pyogenes (group A streptococci)". In Ferretti JJ, Stevens DL, Fischetti VA (eds.). Streptococcus pyogenes: Basic Biology to Clinical Manifestations (2nd ed.). Oklahoma City, United States: University of Oklahoma Health Sciences Center. PMID 36479747. Retrieved May 11, 2023 – via National Center for Biotechnology Information, National Library of Medicine.
  4. ^ Aziz RK, Kansal R, Aronow BJ, Taylor WL, Rowe SL, Kubal M, et al. (April 2010). Ahmed N (ed.). "Microevolution of group A streptococci in vivo: capturing regulatory networks engaged in sociomicrobiology, niche adaptation, and hypervirulence". PLOS ONE. 5 (4): e9798. Bibcode:2010PLoSO...5.9798A. doi:10.1371/journal.pone.0009798. PMC 2854683. PMID 20418946.
  5. ^ Jim Dwyer (July 11, 2012). "An Infection, Unnoticed, Turns Unstoppable". The New York Times. Retrieved July 12, 2012.
  6. ^ Jim Dwyer (July 18, 2012). "After Boy's Death, Hospital Alters Discharging Procedures". The New York Times. Retrieved July 19, 2012.
  7. ^ Pardo S, Perera TB (2023), "Scarlet Fever", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 29939666, retrieved January 14, 2024

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