Mycoplasma pneumoniae and community-acquired pneumonia

Community-acquired pneumonia is an important cause of mortality and hospitalization in all age groups. In temperate climates, Mycoplasma pneumoniae is a common respiratory pathogen causing pneumonia. Information on human Mycoplasma infection in India is scarce.

We aimed to determine the frequency of Mycoplasma pneumoniae infection among patients with community-acquired pneumonia in a prospective cross-sectional study. The assessment included clinical and radiological evaluation followed by microbiological evaluation for the specific pathogen. Microbiological investigations included aerobic and anaerobic blood culture, anti-Mycoplasma IgM antibody detection by gelatin particle agglutination test and ELISA, culture of respiratory tract secretions for Mycoplasma pneumoniae and other organisms, and detection of specific Mycoplasma pneumoniae antigen by indirect immunofluorescence.

Sixty-two patients (42 men and 20 women; mean age 41.7 years) with community-acquired pneumonia were investigated prospectively. They included 42 immunocompetent and 20 immunocompromised patients. Six patients had definitive evidence of Mycoplasma pneumoniae infection and an additional 16 patients had a probable diagnosis. In all, 22 (35.5%) patients with pneumonia had Mycoplasma pneumoniae infection. Of these, 12 patients belonged to the immunocompromised group and 10 to the immunocompetent group. Patients with Mycoplasma pneumoniae infection also had secondary bacterial infection as evidenced by organisms isolated from blood in 50% and from respiratory tract secretions in 68%.

Community-acquired pneumonia has a polymicrobial aetiology, of which the prevalence of Mycoplasma pneumoniae is 35%. The study has two implications: (i) Mycoplasma pneumoniae infection is frequently associated with secondary bacterial infection; and (ii) initial empirical antibiotic therapy for community-acquired pneumonia in India must include antibiotics with activity against Mycoplasma pneumoniae.