Streptococcus pyogenes


The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.

What is Streptococcus pyogenes?

Streptococcus pyogenes is a species within a category of bacteria known as group A ß-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 its also the culprit for the notorious childbed 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 the entry of bacteria through the site of delivery, either the birth canal or, in the case of a 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, and then in the mid 20th century with the advent of sulfa antibiotics, and later penicillin. Additionally, because the immune system cross-reacts between certain GAS proteins and proteins in certain body tissues, several days after a GAS infection, certain autoimmune diseases can develop, namely post-streptococcal glomerulonephritis (PSGN, 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. It was by working with whats called the CRISPR-Cas9 system of S. pyogenes (a kind of microbial immune system to repel attacks by other microbes) that scientists came to harness CRISPR genome editing technology that has been revolutionizing biomedicine, agriculture, and other life sciences, and is poised to bring gene therapy into a new era. However, the reason why S. pyogenes has been a target for study for so long is because of its disease-causing capabilities, which are an issue outside of pregnancy, but also for pregnant women.

How common is Streptococcus pyogenes during pregnancy?

Although the incidence of S. pyogenes infections, including in obstetric settings, declined throughout much of the 20th century, this class of infection has been on the rise since the 1980s and causes more than 75,000 deaths annually around the globe. Compared with non-pregnant women matching their age and medical risk factors, women in the post-partum period have 20 times the risk of GAS infection, most of which are S. pyogenes.

How is S. pyogenes infection during pregnancy diagnosed?

Infection with S. pyogenes is diagnosed by taking a clinical sample from the location of an infection, or entry point to the location of the infection, such as from the throat in the case of pharyngitis, or the vagina, rectum, or urine. Samples are cultures on a growth medium called blood agar on plates, incubated at a particular temperature range, and given whats called a Gram stain and viewed under the microscope. In the blood ager plates, samples are also tested with different antibiotics. The organism is identified based on results, for instance, the appearance of dome-shaped growth of gram-positive organisms whose growth is inhibited by the antibiotic bacitracin, plus certain other test results is enough for a laboratory diagnosis of S. pyogenes. Additional information can be obtained from genetic testing of clinical samples.

Does S. pyogenes cause problems during pregnancy?

GAS infections, S. pyogenes in particular, are the main cause of puerperal fever, which used to be the major cause of mortality of new mothers. Puerperal fever is much less common today, but the organism can cause a range of other problems, including streptococcal pharyngitis (strep throat), endometritis (infection of the endometrium of the uterus, which can lead to sepsis, pelvic or uterine abscess, and peritonitis), sinusitis, streptococcal TSS (which can lead to shock and coma), scarlet fever, impetigo, and necrotizing fasciitis (flesh-eating disease). 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 PSGN, which can lead to kidney failure and heart failure.

Does rheumatic fever during pregnancy cause problems for the baby?

S. pyogenes infections all cause fever. A fever not treated increases the babys risk of having congenital defects involving the heart and other organs. Any of the severe complications that lead to shock can be fatal to the fetus. 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. There is some evidence that these problems also can happen in pregnant women with MVP if the leaflets of the prolapsed mitral valve are deteriorated (what doctors call myxomatous).

What to consider about taking medications when you are pregnant or breastfeeding:

  • The risks to yourself and your baby if you do not treat the S. pyogenes
  • The risks and benefits of each medication you use when you are pregnant
  • The risks and benefits of each medication you use when you are breastfeeding

What should I know about using medication to treat S. pyogenes during pregnancy?

Different regimens of antibiotics are used for different types of S. pyogenes infections, including regimens that are considered fairly safe during pregnancy. Regimens for pharyngitis, for instance, includes different types of oral and injectable penicillin, oral amoxicillin, cephalexin, cefadroxil, clindamycin, azithromycin, clarithromycin, and certain others. 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 puerperal fever, regimens are available with penicillin, amoxicillin, clindamycin, or azithromycin. For treating fever, acetaminophen and paracetamol are thought to be safe during pregna

Who should NOT stop taking medication for S. pyogenes during pregnancy?

In the case of a GAS infection, antibiotics are critical for preventing long-term reactions, such as rheumatic fever. You should not stop an antibiotic regimen before you have completed it, but your doctor can switch you to a different regimen if needed on account of side effects.

What should I know about choosing a medication for my S. pyogenes during pregnancy?

It is important to stay in communication with your health care provider as the release of new studies over time can change the outlook on the role of specific medications during pregnancy.

You may find Pregistrys expert reports about the medications to treat this condition here. Additional information can also be found in the sources listed below.

What should I know about taking a medication for my S. pyogenes when I am breastfeeding?

There are many different antibiotic drugs. Some raise concerns in the setting of lactation, while others do not, depending on whether they have been found to enter breastmilk, and if so, whether they enter breastmilk in significant quantities to do harm. S. pyogenes causes serious infections that may lead to life-threatening complications, avoiding antibiotics generally is not an option.

What alternative therapies besides medications can I use to treat my S. pyogenes infection during pregnancy?

Treatment of the type of infection covered in this report generally depends on good antimicrobial therapy (antibiotics) and good management of fever. However, maintaining good hydration by drinking adequate amounts of liquid can be helpful in addition to the other treatments.

What can I do for myself and my baby when I have an S. pyogenes infection during pregnancy?

Follow the instructions of your physician. The most important consideration S. pyogenes is that it is entirely preventable, but the condition must be recognized and treated early.

Resources S. pyogenes in pregnancy:

For more information about Streptococcus pyogenes during and after pregnancy, contact (800-994-9662 [TDD: 888-220-5446]) or contact the following organizations:

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General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.

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