Case study in infectious disease

Nonrheumatic poststreptococcal myocarditis

Myocarditis is a rare disease with variable clinical presentation and diverse electrocardiographic and echocardiographic features. Viral infection is the most common cause, but myocarditis can also be caused by bacterial infection. The most frequently involved bacterial agent is group A Streptococcus, which is also an etiologic agent of erysipelas. We present the case of a man aged 46 years with left-leg erysipelas who developed myocarditis. Cardiac magnetic resonance played an essential role in diagnosis. This case is, to our knowledge, the first description of an association between erysipelas and myocarditis.

La myocardite est une maladie rare ayant un tableau clinique variable, et diverses caractéristiques électrocardiographiques et échocardiographiques. L'infection virale est la cause la plus fréquente, mais la myocardite peut également être causée par l'infection bactérienne. L'agent bactériologique le plus fréquemment en cause est le streptocoque du groupe A, qui est également un agent étiologique de l'érysipèle. Nous présentons le cas d'un homme âgé de 46 ans ayant un érysipèle à la jambe gauche chez qui une myocardite est survenue. La résonance magnétique cardiaque a joué un rôle diagnostique primordial. À notre connaissance, ce cas montre pour la première fois un lien entre l'érysipèle et la myocardite.

Streptococcal infection is known to be associated with non-suppurative complications, including rheumatic fever. A less well recognized complication is perimyocarditis.

We report 4 cases of myocarditis in young males associated with acute streptoccal infection. Following this clinical observation we employed bioinformatic techniques to identify common epitopes between Streptococcus group A and human muscle proteins. We used Blast to search all the proteome (1697 proteins) of the Streptococcus pyogenes M1 GAS against the human proteome of 34,180 proteins.

4 patients with streptococcal A related myocarditis were treated and made a complete recovery. One cardiac protein, ATP2A2 (NP_733765.1)), a cardiac Ca2+ ATPase, shared an epitope with Streptococcus group A and a high probability of being presented on a MHC Class II molecule.

Streptococcal myocarditis may be a commoner entity than previously appreciated. Bioinformatic techniques have identified a suspected common epitope between the streptococcal proteins and a cardiac Ca2+ ATPase.