Mycoplasma pneumoniae, antibodies

Mycoplasma pneumoniae is a small bacterium that causes infections in the upper respiratory tract. Mycoplasma can be found in the throat and the upper respiratory tract. The bacteria are transmitted by droplets and have a weak transmission capacity. The incubation period is 1–4 weeks. Children, young adults, and immunodeficient adults are the most likely to become ill. Only 5–10% of those infected develop the illness.

The bacteria usually cause a mild, temporary upper respiratory tract infection (runny nose, cough, sore throat, etc.) that does not require treatment, but in about 10% of cases, the symptoms are prolonged. The illness may include symptoms outside the respiratory tract, such as skin (rash), central nervous system (e.g. inflammation of nerve roots), eyes, joints, heart, or liver.

Mycoplasma pneumoniae cannot be discerned from other upper respiratory tract infections based on the symptoms or traditional inflammation tests alone. However, the cells in the immune system form specific antibodies (MypnAb) that can be measured in a blood test.

When should MypnAb be measured?

The test can be carried out if the upper respiratory tract symptoms are prolonged or coincide with other, partially ambiguous or atypical symptoms in other parts of the body.

Symptoms caused by Mycoplasma pneumoniae include:

• Recurring respiratory tract infections
• Prolonged cough
• Pneumonia
• Bronchitis
• Runny nose
• A cough that continues for several weeks
• Fever
• Sore throat
• Headache
• Muscle pain

What does the MypnAb test measure?

The test indicates whether the person has or has had an illness caused by Mycoplasma pneumoniae. The blood can be tested for two types of antibodies: immunoglobulin M (MypnAbM) and immunoglobulin G (MypnAbG). In other words, the test is used to find the body’s response to the potential bacteria, not the bacterium itself.

A recent infection can be diagnosed by testing the blood for immunoglobulin M antibodies. The result is usually positive about one week after the first symptoms.

The immunoglobulin G antibodies do not show until 2–3 weeks after the first symptoms. They are usually measured twice when suspecting a recent infection.