New test for diagnosing M.pneumoniae as cause of blisters

Researchers from the University of Zurich have developed a test to quickly and accurately determine if Mycoplasma pneumoniae is the causative factor in some severe cutaneous and mucous membrane lesions. The investigators say the test could allow doctors to select the right treatment for a patient sooner, without worries about possibly causative medications. “Early [recognition of] inflammatory lesions of the skin and mucous membranes as infection-triggered rather than drug-triggered enables more specific treatment, and most importantly, avoids restriction of possibly causative drugs,” said lead author Dr. Patrick Meyer Sauteur, in a press release. Dr. Sauteur is a consultant in pediatric infectious diseases and hospital epidemiology at the University Children’s Hospital Zurich. In the release, the authors note that rapidly dying mucous membrane cells in the mouth, eye and genital regions, and vesicles and blisters on the skin can be symptoms and signs of drug allergies or infections. One such source of infection is M. pneumoniae, often a cause of pneumonia in children. M. pneumoniae can also be found outside the lungs and trigger severe, painful skin and mucous membrane lesions. However, they note that determining whether M. pneumonia is the cause of a case of blistering is challenging, as routine diagnostic data can only show the presence of the bacteria, not whether it is the cause of the infection vs. merely only having colonized the nasopharyngeal cavity. In an effort to address this challenge, the research group developed an ELISpot (Enzyme-Linked Immunospot) blood test, which can detect specific immune cells (B cells) within 24 hours. These immune cells are directed specifically against M. pneumoniae and only become active during an infection. The new ELISpot blood test has already been used in a childhood pneumonia study at the Children’s Hospital Zurich (JAMA Dermatology [Dec. 18, 2019]). In one-third of 152 children with pneumonia, M. pneumoniae was identified as cause of the infection. Skin and mucous membrane lesions were observed in 23% of these pneumonia cases caused by M. Pneumoniae. Three of the children had severe lesions, predominantly of the mucous membranes. In contrast, only 3% of children who had infections caused by other pathogens experienced skin and mucous membrane lesions. The reason why infections with M. pneumoniae, in addition to respiratory disease, often lead to skin and mucous membrane lesions is not yet fully understood, the authors note in the release. The study showed that the immune system was much more activated in children who were infected with M. pneumoniae and had skin and mucosal lesions than in children with only respiratory tract disease due to M. pneumoniae. “This leads to an interesting conclusion: It may be not M. pneumoniae itself that causes the skin and mucous membrane lesions, but the immune system, which reacts to the bacteria,” said Dr. Sauteur. This new ELISpot blood test makes it possible to investigate the specific immune response in blood in detail and to make an exact diagnosis in patients with M. pneumoniae infections, Dr. Sauteur said. “Our research has a direct impact on treatment management. In patients with M. pneumoniae infections, symptoms may be improved not only through treatment with antibiotics, but also with drugs that modulate the possibly disease-causing immune response.”

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