Understanding Mycoplasma pneumoniae IgG antibodies is helpful when exploring medical test results. This bacterium causes respiratory infections. This article explains what IgG antibodies are in this context and what their presence in your test results signifies.
Understanding Mycoplasma pneumoniae
Mycoplasma pneumoniae is a bacterium that causes respiratory tract infections. It lacks a rigid cell wall, making it resistant to certain antibiotics like penicillin. It commonly causes “atypical pneumonia,” or “walking pneumonia,” due to milder symptoms allowing individuals to continue daily activities.
Infections primarily affect the lungs and other respiratory system parts, including the throat and windpipe. It can infect people of all ages, but is common among school-aged children and young adults. Antibody testing for Mycoplasma pneumoniae is a standard method to determine exposure.
The Role of IgG Antibodies
Antibodies are specialized proteins produced by the immune system in response to foreign substances like bacteria or viruses. Immunoglobulin G (IgG) is the most abundant antibody in the bloodstream, making up approximately 75% of all antibodies. IgG antibodies are part of the body’s long-term immune memory.
When the body encounters a pathogen like Mycoplasma pneumoniae for the first time, it initially produces other antibodies, such as IgM. Subsequently, IgG antibodies are generated as part of a sustained immune response. The presence of IgG antibodies indicates previous encounter and response to a specific pathogen. These antibodies can persist for months or years after infection, providing sustained protection against future encounters. IgG antibodies function by neutralizing pathogens, preventing them from attaching to and entering cells, and by marking them for destruction by other immune cells.
Interpreting Your Test Results
An M. pneumoniae IgG antibody test is ordered for suspected past or ongoing infection, especially with persistent respiratory symptoms or atypical pneumonia. Understanding the results involves considering several possibilities. A “positive” or “reactive” IgG result means Mycoplasma pneumoniae IgG antibodies are detected. This indicates past exposure to the bacterium, a resolved infection, or a chronic infection. A positive IgG result alone does not necessarily mean an active infection, as these antibodies can remain elevated long after the illness clears.
Conversely, a “negative” or “non-reactive” IgG result suggests no Mycoplasma pneumoniae IgG antibodies were detected. This could mean no past exposure to the bacterium, or recent infection where IgG antibodies haven’t sufficiently developed. A negative result can also occur if the immune system did not produce a detectable antibody response or is compromised.
Sometimes, a test result might be “equivocal” or “borderline,” meaning a clear positive or negative cannot be definitively determined. In such cases, your healthcare provider might recommend retesting in 10 to 21 days or correlating with other clinical findings for a conclusive understanding. For a complete picture, IgG results are considered alongside IgM antibody results. While IgG indicates past exposure or long-term immunity, IgM antibodies are produced earlier in an infection and suggest a recent or acute infection. Therefore, both types of antibodies may be tested to determine the timeline of a Mycoplasma pneumoniae infection.