Streptococcus agalactiae: Symptoms, Diagnosis & Treatment

Streptococcus agalactiae, also referred to as S. agalactiae or group B Streptococcus, is a bacteria that is naturally found in the body without causing any symptoms. This bacteria can be found mainly in the gastrointestinal, urinary and, in women, vaginal tracts.

Due to its ability to colonize the vagina without causing symptoms, Streptococcus agalactiae infections are more common in pregnant women. This bacteria can be transmitted to the baby at the time of birth, and is considered to be one of the most common infections in newborns.

In addition to the infection occurring in pregnant women and newborns, the bacteria can also grow and spead in people over the age of 60, as well as in obese populations or those with chronic illnesses, such as diabetes, heart problems or cancer.

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Common symptoms

The main symptoms of a Streptococcus agalactiae include:

  • Fever
  • Chills
  • Nausea
  • Abnromal nervous system functioning
  • Coughing
  • Difficulty breathing
  • Chest pain
  • Joint swelling
  • Redness
  • Increase in temperature at the affected joint site
  • Joint pain

In general, Streptococcus agalactiae infections do not cause symptoms, as this bacterium is naturally found in the body. However, the presence of a weakened immune system or chronic disease can allow this microorganism to overgrow and lead to symptoms. 

Who is most at risk

Streptococcus agalactiae infections can affect anyone, however they are more commonly seen in pregnant women, newborns, people over 60 years of age and people who have chronic diseases, such as congestive heart failure, diabetes, obesity or cancer.

Can Streptococcus agalactiae be sexually transmitted?

Streptococcus agalactiae is part of normal gut flora found in the gastrointestinal system, and can also be found naturally in the vagina and urinary system. Therefore, it is typically not spread through sexual contact. Furthermore, infected pregnant women can transmit the bacteria to their baby during birth, which can cause complications such as septicemia or pneumonia.

Confirming a diagnosis

A Streptococcus agalactiae infection is confirmed through lab tests by collecting a blood, urine, or spinal fluid specimen. This specimen is then cultured and tested for the presence of bacteria.

It can also be tested in vaginal discharge, which is collected with a swab. If results are positive, treatment should be started promptly before birth to prevent the bacteria from growing and spreading to the newborn. Infections in newborns can lead to complications such as pneumonia, meningitis, sepsis or death.

Treatment options

Treatment for Streptococcus agalactiae infections usually involves the use of antibiotics like penicillin, vancomycin, chloramphenicol, clindamycin or erythromycin. These should be taken as prescribed.

When the bacteria reaches the bones, joints or soft tissues, the doctor may prescribe antibiotics and surgical interventions to cleanse and/or remove infected tissue.

Streptococcus agalactiae infections during pregnancy will typically be treated with penicillin as a first-line antibiotic. If this is not effective, the doctor may then prescribe ampicillin.