16S rDNA sequencing of Aggregatibacter actinomycetemcomitans. Infective endocarditis due to Aggregatibacter actinomycetemcomitans in a patient with chronic periodontitis

The HACEK organisms consisting of the non-influenzae Haemophilus sp., Aggregatibacter sp., Cardiobacterium sp., Eikenella corrodens and Kingella sp. are responsible for a sizeable percentage of infective endocarditis cases worldwide with the mortality rate of 18%. Amongst them, Aggregatibacter actinomycetemcomitans is the pathogen most strongly associated with infective endocarditis. Interestingly, A. actinomycetemcomitans forms part of the oral microbiota and is also the etiological agent of periodontitis. Here, we present a case of a 37-year old man with underlying obstructive uropathy, that sought treatment for postural hypotension and symptomatic anaemia with fever. Further clinical examinations later found that he had developed decompensated congestive cardiac failure with aortic regurgitation that required surgical intervention. Cardiac echocardiogram revealed the presence of vegetation in the aortic valve. Blood cultures returned as A. actinomycetemcomitans and species identification was confirmed by MALDI-TOF mass spectrometry and 16S rDNA sequencing. He responded well to furosemide and ceftriaxone, and was transferred to the National Heart Center for further management after completion of intravenous ceftriaxone for 28 days. Chronic periodontitis with plague induced gingivitis was suspected as the origin of the A. actinomycetemcomitans endocarditis. Rapid and accurate diagnosis of fastidious pathogens using MALDI-TOF and 16S rDNA sequencing is crucial for the clinical management and treatment of affected patients