The first case of cholecytitis caused by Aggregatibacter kilianii in Korea

BACKGROUND: The bacterial genus Aggregatibacter was categorized in 2006 to accommodate the former Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, and H. segnis species. Aggregatibacter kilianii is a normal resident of the human upper respiratory tract but can also cause serious infections. A. kilianii is relatively newly identified and has been isolated from conjunctivitis, wounds, abdominal abscesses, and blood. CASE PRESENTATION: An 80-year-old female patient with distal common bile duct cancer was admitted to our hospital with sudden loss of consciousness and general weakness, fever, and abdominal pain for 3 days. Two colonial morphologies were isolated from both the blood and bile cultures; one was identified as Streptococcus constellatus subsp. pharyngis, but the other was not recognized by Vitek2 and MALDI-TOF. The 16 S rRNA sequences showed 99.73% similarity with the sequence of A. kilianii strains. CONCLUSION AND DISCUSSION: This article presents the first case of a clinical isolate of A. kilianii outside Europe. This case is also the first of the antimicrobial profile of this strain. This report highlights the importance of proper molecular identification for timely diagnosis and treatment of disease.