Mycoplasma pneumoniae respiratory infection.

Abstract

1. Nevio Cimolai, MD* 1. 2. *Director, Program of Microbiology, Virology, and Infection Control, Children’s and Women’s Health Centre of British Columbia, Vancouver, BC, Canada. 1. Mycoplasma pneumoniae remains the most common treatable cause of community-acquired atypical pneumonia in children. 2. Common features of M pneumoniae pneumonia include bilateral pulmonary involvement, multifocal or diffuse disease, and reticular infiltrates, but the radiologic manifestations are considerably more diverse. 3. Extrarespiratory manifestations potentially can include several body systems (eg, varied exanthemata, meningoencephalitis, arthropathy). These are either shortly preceded by or coexist with an active respiratory infection. 4. Cold agglutinin serology is of limited diagnostic value for children. 5. Erythromycin and tetracycline remain effective antimycoplasmal antibiotics; beta-lactam agents are not of value. One would anticipate that almost 4 decades of research and clinical experience should leave very little room for ongoing investigation of Mycoplasma pneumoniae . Nevertheless, respiratory infection caused by this pathogen remains common, and advances in science continue as unique attributes of the bacterium and the associated clinical illness unfold. Microbiologic and subsequently other investigations possibly have been delayed in part by the nature of the bacterium. Mycoplasmas are the smallest bacteria, and M pneumoniae in particular is sufficiently fastidious in vitro that few laboratories have provided culture services. Whereas Escherichia coli from a urine sample or Streptococcus pneumoniae from a cerebrospinal fluid specimen may be cultivated luxuriously in 18 to 24 hours, the isolation of M pneumoniae from sputum may require 7 to 21 days. These small, cell wall-deficient bacteria are impossible to visualize in respiratory secretions by either Gram stain or other light microscopic methods. In contrast to the rigid structure of other bacteria, mycoplasmas are pleomorphic (Fig. 1⇓ ). Indeed, the name mycoplasma refers to the plasticity of bacterial forms that crudely resemble some fungal filaments. Mycoplasmas, however, are not even remotely related to or even minimally resemble mycobacteria (eg, Mycobacterium tuberculosis ) or mycologic (ie, fungal) pathogens with respect to most other attributes. The lack of cell wall …