Respiratory Diseases

Mycoplasma pneumoniae Mycoplasma pneumonia is a contagious respiratory infection caused by the bacteria Mycoplasma pneumoniae (M. pneumoniae) . It is easily spread through contact with respiratory fluids and every year, almost 2 million Americans are treated for the disease. It is a leading cause of encephalitis and pneumonia in children and it can cause outbreaks in areas of close personal contact such as schools and military barracks. Antigen and Antibody Detection Assays

M. pneumoniae can cause a host of symptoms such as primary atypical pneumonia, tracheobronchitis, and upper respiratory tract disease. Tracheobronchitis is most common in children with a reduced immune system, and up to 18% of infected children require hospitalization. Clinically, M. pneumoniae cannot be differentiated from pneumonia caused by other bacteria or viruses. A specific diagnosis is important because treatment of M. pneumoniae infection with β -lactam antibiotics is ineffective, whereas treatment with macrolides or tetracyclines can reduce the duration of the illness. Adherence of M. pneumoniae to the respiratory epithelium is the first step in the infection process. This attachment process is a complex event that requires several adhesin proteins, such as P1, P30, and P116. The true incidence of M. pneumoniae associated infection is not clear as it difficult to diagnose in the early stages of infection. To date, most commercial antibody detection assays for M. pneumoniae use partially purified lysates, although it has been demonstrated that a P1-enriched antigen increases the sensitivity and specificity of serologic diagnosis. Until recently, it has not been possible to develop a specific antigen for M. pneumoniae P1 due to an unusual UGA stop codon in the reading frame, leading to the premature termination of this protein in E. coli. M. pneumoniae P1 antigens are now readily available to enable the development of better performing EIA assays for both antigen and antibody detection specific to M. pneumoniae .

MYCOPLASMA PNEUMONIAE STRUCTURE

Source: Physiological Reviews, American Physiological Society

Diagnosis The standard methods for detection of M. pneumoniae include culture, serology (conventionally this been limited to the complement fixation (CF) test, which predominantly measures IgM antibodies), and PCR. Immunoassays have been found to be more sensitive for the detection of acute infection than culture and have a sensitivity comparable to PCR. Traditionally, most commercial antibody detection assays for M. pneumoniae use partially purified lysates to detect specific IgG, IgM or IgA antibodies to distinguish between an acute or past infection. However, recombinant antigens have increased in popularity in recent years and research has demonstrated that a P1-enriched antigen increases the sensitivity and specificity of serologic diagnosis.