Streptococcus pyogenes

References

Images

Streptococcus pyogenes

puerperal fever

Streptococcus pyogenes

Streptococcus pyogenes

bacterium

Also known as: group A streptococcus

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 14, 2026

Quick Summary

Streptococcus pyogenes — Streptococcus pyogenes Photomicrograph of Streptococcus pyogenes, a bacterium that can cause scarlet fever. (Magnified about 900×.)

Streptococcus pyogenes is a type of spherical bacterium that belongs to the genus Streptococcus. These bacteria are characterized by their gram-positive nature and their tendency to form chains, resembling a string of beads.1

S. pyogenes, also known as group A streptococcus, is responsible for various human infections. These include common ailments like strep throat, tonsillitis, and scarlet fever, which is distinguished by a red rash caused by an erythrogenic toxin. It can also cause more severe conditions such as impetigo, rheumatic fever, and, in rare but serious cases, necrotizing fasciitis, popularly termed the "flesh-eating disease".12

While some streptococci cause disease, others are beneficial, playing a role in the production of fermented foods like cheese and buttermilk.1

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

2 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

streptococcus
Streptococcus pyogenes, often referred to as group A streptococcus bacteria, can cause rheumatic fever, impetigo, scarlet fever, puerperal fever, streptococcal toxic shock syndrome, strep throat, tonsillitis, and other upper respiratory infections. Necrotizing
Read More
Streptococcus pyogenes, often referred to as group A streptococcus bacteria, can cause rheumatic fever, impetigo, scarlet fever, puerperal fever, streptococcal toxic shock syndrome, strep throat, tonsillitis, and other upper respiratory infections. Necrotizing
Read More

methicillin
>Streptococcus pyogenes, which can cause scarlet fever, and S. pneumoniae, which can cause pneumonia.
Read More
>Streptococcus pyogenes, which can cause scarlet fever, and S. pneumoniae, which can cause pneumonia.
Read More

necrotizing fasciitis
…variety of pathogenic bacteria, principally Streptococcus pyogenes, also known as the group A streptococcus. Popularly known as the flesh-eating disease, necrotizing fasciitis is an uncommon condition. It can lead to life-threatening illness and death, with mortality rates approaching 50 percent.
Read More
…variety of pathogenic bacteria, principally Streptococcus pyogenes, also known as the group A streptococcus. Popularly known as the flesh-eating disease, necrotizing fasciitis is an uncommon condition. It can lead to life-threatening illness and death, with mortality rates approaching 50 percent.
Read More

puerperal fever
…commonly producing this infection are Streptococcus pyogenes; staphylococci (inhabitants of the skin and of pimples, carbuncles, and many other pustular eruptions); the anaerobic streptococci, which flourish in devitalized tissues such as may be present after long and injurious labour and unskilled instrumental delivery; Escherichia coli and Clostridium welchii (inhabitants of…
Read More
…commonly producing this infection are Streptococcus pyogenes; staphylococci (inhabitants of the skin and of pimples, carbuncles, and many other pustular eruptions); the anaerobic streptococci, which flourish in devitalized tissues such as may be present after long and injurious labour and unskilled instrumental delivery; Escherichia coli and Clostridium welchii (inhabitants of…
Read More

scarlet fever
…hemolytic streptococcal bacteria, in particular Streptococcus pyogenes. Scarlet fever can affect people of all ages, but it is most often seen in children. It is called scarlet fever because of the red skin rash that accompanies it.
Read More
…hemolytic streptococcal bacteria, in particular Streptococcus pyogenes. Scarlet fever can affect people of all ages, but it is most often seen in children. It is called scarlet fever because of the red skin rash that accompanies it.
Read More

sinusitis
Staphylococcus aureus, Streptococcus pyogenes, and many other penicillin-sensitive anaerobes.
Read More
Staphylococcus aureus, Streptococcus pyogenes, and many other penicillin-sensitive anaerobes.
Read More