Streptococci A and B are bacteria responsible for many infections, some of which are very serious. How can we catch them? What is the contagion period? Symptoms ?
“A streptococcal infection is a microbial attack because streptococcus is a bacterium (rudimentary unicellular living being that has a metabolism). An infection is characterized by an attack on one or more tissues with generally partial destruction of the infected tissues.“Informs Dr. Stéphane Gayet, Infectiologist and hygienist at the University Hospitals of Strasbourg.This infectious process has two major components: pathogenic bacteria divide quickly and form an invasive critical mass (virulence) and in addition they produce toxins which are very dangerous“ he specifies. There are many bacteria of the genus Streptococcus. Streptococcal A infections (Streptococcus pyogenes) and B (Streptococcus agalactiae) are less frequent now due to high consumption of antibiotics ; however, these streptococci have remained sensitive to antibiotics, so fewer people carry them.
Streptococci A and B are quite similar. They belong to the same group of streptococci. “These are virulent and toxigenic strains, especially streptococcus A“says Dr. Stéphane Gayet. Group A beta-hemolytic streptococcus or Streptococcus pyogenes is specific to the human species. “Its habitat is the back of the throat, therefore the pharynx, and it has a rich pathogenic power“ inform the infectiologist.
Streptococcus B (Streptococcus agalactiae) is not specific to humans even though it is a predominantly human bacterium. It is found in some animals but the exchange with the animal is not very frequent. “Its habitat is the intestine and the vagina” teaches Dr. Stéphane Gayet. It can become dangerous if pregnancy where it can be transmitted to the newborn at the time of delivery and cause serious infections such as meningitis or pneumonia. This is why systematic screening at the end of pregnancy is carried out by vaginal sampling. If positive, an antibiotic is given intravenously to the mother as a preventive measure from the start of labor until birth.
Streptococci A and B are not commensal bacteria (which physiologically belong to the microbiota). It is not “normal” to have streptococci in our body but people are healthy carriers : they harbor them, tolerate them and do not know it because they do not develop disease but they are contagious. They can transmit streptococcus. “For example, a carrier who has put their hands in their mouth can transmit strep A or B by shaking hands with another person. Anything that goes to the mouth is the primary mode of entry for strep A and B“explains Dr. Stéphane Gayet. “You can be contaminated without knowing it, hence the importance of having systematic hygiene measures: wash one’s hands before touching food, after putting hands in mouth and before putting them in mouth… ” recommends this specialist.
“Contagiousness (time during which a person remains contagious) becomes almost zero after 48 hours of antibiotic treatment“Informs Dr. Gayet.
Very high fever, chills, pain, deterioration of general condition are warning signs.
Symptoms depend on location. “Streptococcus A in particular gives very marked signs. Symptoms (what you feel) and signs (what you see) are very noisy: very high fever (39-40•C), chills, pain, deterioration of general condition…“Informs Dr. Stéphane Gayet. “Erysipelas (skin infections) is indicated by widespread redness on a limb or on the face, a very high fever, chills” he indicates.
► Streptococcus A is at the origin of red (erythematous) or red with white dots (erythemato-pultaceous) angina, of scarlet fever, a more serious form of angina. It also leads to skin infections: erysipelasa serious infection that often requires hospitalization, and which is seen more in people with overweight or lymphatic and venous circulation disorders; impetigo, especially in tropical countries. Streptococcus A is also the cause of sepsis often fatal, especially from sepsis afterchildbirth (puerperal fever), dermo-epidermatitis necrotizing (necrotizing fasciitis, necrotizing cellulitis) which occurs mostly in hospital after surgery. There is also streptococcal A pneumonia.
► “Streptococcus B has a slightly less intense pathogenic power. It is especially formidable in newborns.“ teaches the infectiologist. “Newborns can get sepsis after birth due to vaginal contamination when a woman is a carrier of streptococcus B in the vagina, he explains. This is why a vaginal and rectum sample is taken at the end of pregnancy, at the 35th week. If positive, the vagina is temporarily decolonized with antibiotic treatment before labor “says the specialist. Streptococcus B also gives angina and septicemia in adults.
A streptococcal A infection often causes a significant passage of the bacteria in the blood.
“The diagnosis is mainly clinical. A doctor who has experience quickly identifies a streptococcal infection which presents typical clinical signs (high fever, deterioration of general condition, usual locations…)” inform the specialist. There is a test of rapid diagnosis for strep throat (biological test) and blood cultures can be performed. A streptococcal A infection often causes a significant passage of the bacteria in the blood. Of the blood samples (blood cultures) are cultured in flasks to identify the bacteria. Of the local levies (swab and culture) can also be done, for example in case of erysipelas. Usual blood tests (NFS) can detect infection (increased CRP, leukocytosis).
Streptococcal A and B infections are treated with antibiotics. “The best antibiotic is penicillinespecially amoxicillin (CLAMOXYL)“Informs Dr. Stéphane Gayet. The duration of treatment depends on the severity of the disease, from 4 days to three weeks.
Thank you to Dr Stéphane Gayet, infectious disease specialist and hygienist at the University Hospitals of Strasbourg.