Septic Shock, Infective Endocarditis, Septic Embolization and Disseminated Intravascular Coagulation Caused by a Toxigenic C. diphtheriae Strain: A Case Report

Background: Diphtheria is an acute infectious disease caused by Corynebacterium diphtheriae. Despite several worldwide outbreaks, it is now considered a rare disease by industrialized countries. Clinical manifestations usually account for oropharyngeal lesions, but rare cases of systemic involvement (mainly endocarditis) have been described among non-toxigenic strains. Case description: We report the case of a patient who experienced septic shock, disseminated intravascular coagulation and multiorgan failure due to Corynebacterium diphtheriae infection. The pathogen was further characterized as a highly toxigenic strain. Infective endocarditis with mitral and aortic valve vegetations led to early multiorgan septic embolization. Major stroke, liver function impairment, heart failure and acute kidney injury were the main findings. Unlike the typical forms of infection caused by this pathogen, there was no evidence of airway or skin involvement. Furthermore, apart from hemocultures, none of the other investigations (pharyngeal swabs, bronchoalveolar lavages, urine culture) ever tested positive for the bacteria. Conclusions: The report we present describes a case of C. diphtheriae infection with many atypical characteristics: (i) lack of any pathognomonic signs or symptoms; (ii) extensive endocarditic process (very uncommon for toxigenic strains); (iii) early septic emboli development, with rapid evolution to multiorgan failure; (iv) detection of disseminated intravascular coagulation. Despite disseminated intravascular coagulation being a known complication of septic shock, regardless of the etiological agent, according to our literature research, this is the second known case driven by C. diphtheriae infection in an adult.