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Streptococcus pyogenes is a species within a category of bacteria known as group A β-hemolytic Streptococcus (GAS). GAS can cause a variety of infections, including streptococcal pharyngitis (strep throat), scarlet fever, impetigo, endometritis, streptococcal toxic shock syndrome (TSS), sinusitis, and necrotizing fasciitis (“flesh-eating disease”). Not only is S. pyogenes responsible for the majority of such GAS conditions, but it’s also the culprit for the notorious “childbirth fever”, also called puerperal fever, that used to kill numerous women soon after giving birth in the days when so-called “natural” childbirth was the only way that women gave birth. Puerperal fever is an infection, usually around the site where the placenta detaches in the uterus, due to entry of bacteria through the site of delivery, either the birth canal, or, in the case of cesarean section through the abdomen. The incidence of this condition began to decline in the late 19th century as doctors came to understand the role of bacteria in disease and the use of sanitary procedures. It declined further in the middle of the 20th century with the advent of sulfa antibiotics, and later penicillin. Nevertheless, this infection has been on the rise since the 1980s and causes more than 75,000 deaths each throughout the world. Women in the post-partum period have an especially high risk of being hit with a GAS infection, especially S. pyogenes.
When the immune system is stimulated by GAS proteins, it reacts against proteins of certain body tissues. Consequently, several days after a GAS infection, certain autoimmune diseases can develop. These include post-streptococcal glomerulonephritis (a kidney condition) and rheumatic fever, which leads to long-term complications, especially in the heart. Because S. pyogenes is such a major contributor to disease, microbiologists have studied this organism extensively and a lot is known about how it defends itself against other bacteria.
Infection with S. pyogenes is diagnosed by taking a sample from the location of an infection, such as the female genital tract. In a process called culturing, samples are grown on plates containing blood and various nutrients (blood agar). The samples must be kept at particular temperature range. When ready, they are treated with a special stain and viewed under the microscope. They are also treated with different antibiotics and based on all of this they can be identified. In the case of S. pyogenes, this organism is identified based on the appearance of dome shaped growth of organisms that staining tests prove are what microbiologists call ‘gram-positive’ and whose growth is inhibited by the antibiotic bacitracin. Genetic testing of the samples can add to the diagnosis.
While childbirth fever is much less common today than it used to be, S. pyogenes can cause a range of other problems, including streptococcal pharyngitis (strep throat), endometritis (infection of the endometrium, the inner lining of the uterus), sinusitis, streptococcal toxic shock syndrome (TSS), scarlet fever, impetigo, and necrotizing fasciitis (“flesh-eating disease”). Endometritis, in turn, can lead to sepsis, pelvic or uterine abscess, and peritonitis, while streptococcal TSS can lead to shock and coma.
If not treated quickly with appropriate antibiotics, such conditions, especially streptococcal pharyngitis, can lead to rheumatic fever, and over many years rheumatic heart disease. Similarly, these infections, especially streptococcal impetigo, can lead to the kidney complication mentioned above, post-streptococcal glomerulonephritis, which can lead to kidney failure and heart failure.
S. pyogenes infections cause fever, which must be treated to protect the baby against congenital defects involving the heart and other organs. If you develop rheumatic heart disease (RHD), this can result in premature labor and delivery, intrauterine growth retardation (the fetus grows too slowly in the womb), low birth weight, fetal death, and death of the newborn soon after birth.
To treat S. pyogenes infections, doctors can give a variety of antibiotics, including regimens that are safe during pregnancy. If you are allergic to one type of antibiotic, another effective type can be selected for you. Acute rheumatic fever (ARF) can be treated with non-steroidal anti-inflammatory drugs (such as ibuprofen), salicylates (such as aspirin), or corticosteroids. For treating childbirth fever, medication combinations available with penicillin, amoxicillin, clindamycin, or azithromycin. For treating fever, acetaminophen and paracetamol are thought to be safe during pregnancy.
Although S. pyogenes has caused a great deal of disease in women who have just given birth, this organism is also key to a revolution that is occurring in medicine, agriculture, and throughout life sciences. Working with the CRISPR-Cas9 system of S. pyogenes, a kind of microbial immune system that protects bacteria and other microorganisms from viruses, scientists developed CRISPR genome editing technology. Using this system, researchers can can out and replace particular genes and segments of genes within an organisms. CRISPR editing also is poised to bring gene therapy into a new era.