Group A Streptococci

OVERVIEW OF Group A Streptococci :

Streptococcus is a gram positive bacteria , it is a ubiquitous organism and it is the most common bacterial cause of acute pharyngitis.

Disease caused by the bacterium:

Streptococcal throat  infection


Scarlet fever


Necrotizing fascitis

Toxic shock syndrome


Rheumatic fever

STRUCTURE of Group A Streptococci :

It is defined as a gram positive bacteria genus composed of streptococcus pyogens strains. Group A streptococcus strains have  a similar surface antigen recognized by laboratory test. These antigen are called as Lancefield group A antigen. This Lancefield group consists of different streptococcus species groups with specific antigens and are distinguished by specific antibody tests. These tests are mentioned because they are frequently used to distinguish group B, Grop C and other streptococcus groups. Group A streptococcus bacteria appear as pairs and chains when gram stained.

These pyogens bacterial species have many components that contribute to the pathogen’s ability to cause the disease.

Lipoteichoic acid on its surface helps the GAS bacteria to bind to epithelial cell membranes.

M proteins (over 100 types on the GAS bacterial strains) help the bacteria resist immunologic host defenses.

Exotoxins (for example, DNAses A, C and D, streptolysin S, proteinase, streptokinase, and pyrogenic exotoxins [A-D])

Human immune system stimulators (for example, streptolysin O, DNAse B, and hyaluronidase)

M proteins exotoxins cause scarlet fever rash, damage organs and cause shock and inhibit the human immune system, while the human immune system stimulators amy stimulate the immune system to produce antibodies that likely play a rle in the development of autoiimune responses that might lead to glomerulonephritis or acute rheumatic fever.

In most instances, GAS bacteria are contracted via person to person contact with mucus,skin or infected lesions . Spread of the GAS organisms occurs infequently by items that have made contact with the infected people.

however many people are colonized with GAS bacteria.  Vertical transmission is also possible that the transmission from the mother to child.


Streptococcal throat infection:

Sore throat that can start very quickly

Pain when swallowing


Red and swollen tonsils sometimes white patches or streak of pus may appear

Tiny red spots which are termed as petechiae on the roof of the mouth is seen

Swollen lymph nodes in front of the neck region

Hoarseness of voice

It takes atleast 5 days for the person to get ill when he is exposed to the infection.

Routes of transmission:

Streptococcal: Close contact with another person with strep throat is the most common risk factor for illness. Streptococcal infection is more among the school going students.

Scarlet fever:

It is the mild infection and it usually takes two to five days for the person to get the disease  when exposed to group A strep to become sick. Illness usually begins with a fever and sore throat. There may be clinical presentation such as chills, vomiting or abdominal pain. The tongue may have a whitish coating and appear swollen and hence it is called as strawberry like tongue appearance. The throat and tonsils may be very red and sore and swallowing may be painful.

One or two days after the illness begins, a red rash usually appears. However, the rash can appear before illness or up to 7 days later. The rash may first appear on the neck, underarm, and groin (the area where your stomach meets your thighs). Over time, the rash spreads over the body. The rash usually begins as small, flat blotches that slowly become fine bumps that feel like sandpaper.



The bacteria that can cause Impetigo are  group A streptococcus and staphylococcus aureus. When group A str[ infects the skin it causes sores. The bacteris is contagious when anyone touches the sore of the patient.

Signs and symptoms:

It starts as a red itchy sore. As it heals a crusty yellow os honey coloured scab forms over the sore. The impetigo can occur anywhere in the body. It most often affects exposed skin such as around the nose and mouth or on the arms and legs. Symptoms include red, itchy sores that break open and leak a clear fluid or pus for a few days. Next, a crusty yellow or “honey-colored” scab forms over the sore, which then heals without leaving a scar.

It usually takes 10 days for sores to appear after someone is exposed to group A strep.

Rubbing the antibiotics cream on the skin or taking the antibiotics orally can relieve the symptoms.


It is the bacterial infection that is present beneath the skin surface. Staphylococcus and Streptococcus are the two types of bacteria that takes part in the cellulitis. Sometimes the cellulitis develops in the area that has open wounds or at ulceration site.

Cellulitis symptoms include:

  • pain and tenderness in the affected area
  • redness or inflammation of your skin
  • a skin sore or rash that grows quickly
  • tight, glossy, swollen skin
  • a feeling of warmth in the affected area
  • an abscess with pus
  • fever

More serious cellulitis symptoms include:

  • shaking
  • chills
  • fatigue
  • dizziness
  • lighteadedness
  • feeling ill
  • warm skin
  • sweating
  • muscle aches

Symptoms like these could mean that cellulitis is spreading:



Red streaks

Rheumatic fever:

It is infection that results in pain in joints, also affects the brain and heart, skin. It develops when the scarlet fever or strep throat is not treated properly.

Toxic shock syndrome:

It is a serious bacterial infection. It can develop very quickly in low blood pressure , multiple organ failure patients and it is a fatal condition.


The main diagnostic feature is the formation of the beta hemolytic streptoccus colony in the blood agar which shows bacitracin coating in it. It shows catalase and Hippurate test negative.


Antibiotics regimen such as amoxicillin, ampicillim, clavulanic acid, clindamycin or third generation cephalosporins can be used.



The prognosis is good with the antibiotic treatment.


Protect Yourself and Others

People can get impetigo more than once. Having impetigo does not protect someone from getting it again in the future. While there is no vaccine to prevent impetigo, there are things people can do to protect themselves and others.

Wound Care

Keep sores caused by impetigo covered in order to help prevent spreading group A strep to others. If you have scabies, treating that infection will also help prevent impetigo.

Good wound care is the best way to prevent bacterial skin infections, including impetigo:

  • Clean all minor cuts and injuries that break the skin (like blisters and scrapes) with soap and water.
  • Clean and cover draining or open wounds with clean, dry bandages until they heal.
  • See a doctor for puncture and other deep or serious wounds.
  • If you have an open wound or active infection, avoid spending time in:
    • Hot tubs
    • Swimming pools
    • Natural bodies of water (e.g., lakes, rivers, oceans)


Appropriate personal hygiene and frequent body and hair washing with soap and clean, running water is important to help prevent impetigo.

The best way to keep from getting or spreading group A  strep is to wash the hands properly often. This is especially important after coughing or sneezing. To prevent group A strep infections, you should:

  • Cover your mouth and nose with a tissue when you cough or sneeze.
  • Put your used tissue in the waste basket.
  • Cough or sneeze into your upper sleeve or elbow, not your hands, if you don’t have a tissue.
  • Wash your hands often with soap and water for at least 20 seconds.
  • Use an alcohol-based hand rub if soap and water are not available.

You should wash the clothes, linens, and towels of anyone who has impetigo every day. These items should not be shared with anyone else. After they have been washed, these items are safe for others to use.


People diagnosed with impetigo can return to work, school, or daycare if they:

  1. Have started antibiotic treatment
  2. Keep all sores on exposed skin covered

Use the prescription exactly as the doctor says to.

Once the sores heal, someone with impetigo is usually not able to spread the bacteria to others.