A Compendium for Mycoplasma pneumoniae

Abstract

Historically, atypical pneumonia was a term used to describe an unusual presentation of pneumonia. Currently, it is used to describe the multitude of symptoms juxtaposing the classic symptoms found in cases of pneumococcal pneumonia. Specifically, atypical pneumonia is a syndrome resulting from a relatively common group of pathogens including Chlamydophila sp., and Mycoplasma pneumoniae. The incidence of M. pneumoniae pneumonia in adults is less than the burden experienced by children. Transmission rates among families indicate children may act as a reservoir and maintain contagiousness over a long period of time ranging from months to years. In adults, M. pneumoniae typically produces a mild, "walking" pneumonia and is considered to be one of the causes of persistent cough in patients. M. pneumoniae has also been shown to trigger the exacerbation of other lung diseases. It has been repeatedly detected in patients with bronchitis, asthma, chronic obstructive pulmonary disorder, and cystic fibrosis. Recent advances in technology allow for the rapid diagnosis of M. pneumoniae through the use of polymerase chain reaction or rapid antigen tests. With this, more effort has been afforded to identify the causative etiologic agent in all cases of pneumonia. However, previous practices, including the overprescribing of macrolide treatment in China and Japan, have created increased incidence of macrolide-resistant M. pneumoniae. Reports from these countries indicate that >85% of M. pneumoniae pneumonia pediatric cases are macrolide-resistant. Despite its extensively studied past, the smallest bacterial species still inspires some of the largest questions. The developments in microbiology, diagnostic features and techniques, epidemiology, treatment and vaccines, and upper respiratory conditions associated with M. pneumoniae in adult populations are included within this review.

Keywords: CARDS toxin; Mycoplasma pneumoniae; atypical pneumonia; community-acquired pneumonia; pneumonia; walking pneumonia.

FIGURE 1

A longitudinal schematic depicting the cellular architecture of Mycoplasma pneumoniae. It contains known structural features including cell shape, lack of flagella, a terminal organelle including the “rod” composed of two segmented plates, one thick and one thin, and a wheel (bowl) complex with fibrils extending throughout the cytoplasm. The outer cell membrane is integrated with membrane proteins while the inner lining encloses the cytoplasm. Image is not to scale.

FIGURE 2

Possible schematic for pathogenesis of human M. pneumoniae. CARDS, Community Acquired Respiratory Distress Syndrome; ATP, adenosine tri-phosphate; K, potassium; ICAM, intracellular adhesion molecule; NADPH, nicotinamide adenine dinucleotide phosphate; ROS, reactive oxygen species; TLR, toll like receptor.

FIGURE 3

Interpolated M. pneumoniae incidence from 2000 to 2012. These statistics were calculated using linear interpolation from reported incidence found within the literature. Gray countries were incalculable. This interpolation process did not take into account any genetic, cultural, environmental, social, or other differences across the various countries and regions. Thus, interpolations may have very limited relevance to the actual incidence of M. pneumoniae in any region. Image created using R v.3.2.2 with the package choroplethr.