Chlamydia pneumoniae infection-associated erythema multiforme.

There is a well-known correlation between Herpes simplex (HSV) infection and erythema multiforme (EM). More recently, in Japan, it was found that Chlamydia pneumoniae (Cp) may promote the development of EM. All cases of Cp infection-associated EM that had been diagnosed in our clinic over the past two years (from 2011 to 2012) were analyzed. Cp infection was diagnosed on the basis of a significant increase (>2.00) in anti-Cp IgM titers, as measured by the HITAZYME-ELISA test. There were 7 cases of Cp-EM, one male and 6 females. Median age was 13 years (range 3-29 years). It is recommended that the possible involvement of Cp infection, besides HSV or Mycoplasma pneumoniae infections, should be considered in all cases of EM.