Fatal Respiratory Tract Infections With Mycoplasma pneumoniae

Mycoplasma pneumoniae is a prokaryotic microorganism that lacks a rigid cell wall and has a high affinity for respiratory epithelial cells. M. pneumoniae has been shown to be a major pathogen leading to severe, potentially life-threatening respiratory tract infections. The organism itself is too small to be detected at light microscopy. Histopathological features of the disease include two patterns of injury represented by (a) circumscribed bronchiolitis and (b) organizing pneumonia, the latter corresponding to a generalized inflammatory process spreading from M. pneumoniae's primary target zone, the bronchi and bronchioli. In M. pneumoniae-associated bronchiolitis, the mucosa of the upper and lower airways appear edematous and infiltrated by a dense predominantly mononuclear infiltrate accompanied by an intraluminal exsudate of neutrophils and, to a lesser extent, macrophages. Occasionally, plugs of granulation tissue within the lumen of bronchi and bronchioli corresponding to bronchiolitis obliterans can be seen. M. pneumoniae-organizing pneumonia is characterized by a dense mononuclear infiltrate in alveolar septa and alveolar spaces that is frequently accompanied by intraalveolar hemmorhages and edema. The lungs may additionally show features of diffuse alveolar damage including type II pneumocyte hyperplasia, squamous metaplasia, and hyaline membranes as well as occlusive venous thromboses. To enable etiopathogenetic conclusions concerning a causal relationship between M. pneumoniae infection and fatal outcome, for example, in cases of alleged medical malpractice, the forensic investigation should ensure postmortem blood sampling as early as possible with subsequent enzyme-linked immunosorbent assay-based serological determination of IgA and IgM antibodies as well as an immediate autopsy to obtain native lung specimens for direct detection of M. pneumoniae using standard polymerase chain reaction. Intrinsic and extrinsic risk factors predisposing to the development of fatal M. pneumoniae infection have to be considered carefully in the following expert witness. From the medicolegal point of view, the sudden, unexpected death of an individual occurring outside hospital as the sequel of a rapidly progressive course of M. pneumoniae infection will have to be regarded as unavoidable in most cases. However, data obtained from such instances are valuable since fatal respiratory tract infections with M. pneumoniae in individuals dying outside hospital are probably underestimated.