Staphylococcus aureus


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 Staphylococcus aureus infection?

Staphylococcus aureus is a species of bacteria that lives on the skin, or in the nose, of many people. As long as it stays in these areas of the body, S. aureus is not harmful, but it can produce severe disease if it penetrates the body through a wound or other opening. Infection with S. aureus can come from ones skin, or through contact with somebody else.

Doctors and public health officials are particularly concerned with a strain of S. aureus called methicillin-resistant Staphylococcus aureus (MRSA). MRSA has its name because it is resistant to (does not stop growing when exposed to) a particular antibiotic called methicillin that kills other strains (called methicillin-sensitive S. aureus strains, MSSA), but MRSA also resists treatment with various other antibiotics. Because it can be on the hands of anybody, including hospital visitors who dont normally wash their hands, patients are vulnerable to MRSA through wounds and incisions (including minor openings between the air and blood that can happen during vaginal delivery), and even simple intravenous lines. This can include pregnant women.

How common is S. aureus infection during pregnancy?

Up to one-third of people may carry S. aureus on their bodies. In an estimated 2 percent of these people, their S. aureus is MRSA. The risk of infection during hospital procedures, including during pregnancy, has been decreasing over the past several years, because of strong attention to infection control, but there is concern about MRSA infecting new mothers, particularly those getting a cesarean section. It has been notoriously difficult to study and compute the rates of both MSSA and MRSA across countries and cities, but when women develop sepsis (infection throughout the body) associated with giving birth, or with gynecologic procedures, S. aureus may account for 20 -30 percent or more of such cases.

How is S. aureus infection during pregnancy diagnosed?

The workup toward a diagnosis starts with doctors taking a sample from the location on the body that is infected. This can be an infected wound, blisters with pus, or something else on the outside of the body, or it can be sputum if the problem is pneumonia (the lung is infected). Doctors in the laboratory then attempt to culture bacteria from the sample, meaning to get it to grow in a solution containing nutrients. Whatever grows is tested with certain biochemical techniques that can identify the genus Staphylococcus. If Staph is indeed present, it is spread onto what are called blood agar plates, and this reveals whether or not the species is S. aureus. If S. aureus is found, it is then tested further to see if it is resistant to methicillin and other antibiotics.

Does S. aureus cause problems during pregnancy?

During pregnancy, S. aureus thats from your skin, or contact with somebody else, can become an infection if it descends into the skin, in which case it produces redness, warm swelling, pain, and pus. The infection also can move deeper into the body, in which case it produces chills and fever, pain, confusion, and loss of balance. Pneumonia is also possible, which also produces fever and chills, along with breathing difficulty or coughing, and often chest pain.

Does S. aureus during pregnancy cause problems for the baby?

A newborn can develop an S. aureus infection from an infected mother, other during delivery, or after birth. If this happens, the infection could work its way to the newborns lungs causing pneumonia, or throughout the newborn causing sepsis, putting the newborns life at serious risk. Its important to know that this is extremely rare.

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. aureus.
  • 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. aureus during pregnancy?

S. aureus infections must be treated with antibiotic medication. If it is an MSSA strain, there usually are several antibiotic choices, making it possible to minimize risk to the developing baby or newborn. On the other hand, if the infection is MRSA, the options may be reduced to just a few possible medications, or even just one.

Who should NOT stop taking medication for an S. aureus infection during pregnancy?

Everybody who is given antibiotic treatment for an S. aureus infection during pregnancy must adhere to the treatment because such an infection is life-threatening and curable with an appropriate antibiotic (an antibiotic to which the particular strain has no resistance).

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

The choice of antibiotic medication is determined by testing done on bacterial cultures from the body, which indicates which drugs are effective against the particular S. aureus strain.

You may find Pregistrys expert reports about the individual medications used to treat S. aureus here. Additional information can also be found in the sources listed at the end of this report.

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

There are many different antibiotic drugs. Some are a concern during breastfeeding while others are not, depending on whether they have been found to enter breast milk, and if so, whether they enter breast milk in significant quantities to do harm. S. aureus is a serious, life-threatening infection, and sometimes there are few or no choices between one drug or another, particularly if the infection is MRSA. In such cases, the choice is a matter of life or death. Certain drugs, one called sulfamethoxazole, for instance, is thought to be relatively safe for a nursing infant if the infant is healthy, while there is concern regarding some other drugs.

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

There is no alternative to antibiotic medications if you already have an S. aureus infection. However, some things can be done in the area of prevention. This includes hand washing and overall cleanliness, but it also includes a more aggressive approach known as decolonization, in which carriers of S. aureus, MRSA in particular, and their skin, nose, or other areas are cleaned out using chemical agents that kill the strain, allowing it to be replaced with other bacterial species that do not cause disease.

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

Cooperate with health care providers and accept hospitalization if it is recommended for you. Also, keep in mind that S. aureus infections are preventable to a certain extent through careful handwashing and other precautions.

Resources for S. aureus in pregnancy:

For more information about S. aureus 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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