Hypervirulent Klebsiella pneumoniae liver abscess: A case series of invasive disease and complications at an academic community healthcare system in Cambridge, Massachusetts

Abstract

Background. Severe invasive disease caused by hypervirulent Klebsiella pneumoniae was first reported in the 1980s in Taiwan with subsequent cases seen in Southeast Asian countries, including Korea, Vietnam, and Japan. However, there has been an increasing incidence in other areas around the world, including North America. Our objective was to characterize patients with hypervirulent Klebsiella pneumoniae liver abscesses by clinical course and microbiologic data. Methods. This was a retrospective case series of inpatients from 2015 to 2017 at Cambridge Health Alliance, an academic community healthcare system including Cambridge and Everett hospitals. Included patients all had a solitary Klebsiella pneumoniae liver abscess with microbiologic confirmation. Data collected included gender, age, country of origin, comorbidities, and clinical complications and outcomes. Klebsiella isolates were sent for genetic sequencing and colonies were grown on agar to evaluate for hypermucoviscosity. Results. Five patients were included with Klebsiella pneumoniae liver abscess. The age ranged from 53 to 74 years old, all patients were male, three patients were from Haiti and two were from Vietnam, and comorbidities included: diabetes 3/5 (60%), hypertension 1/5 (20%), and COPD 1/5 (20%). Mortality was not observed in any of these patients, however, 4/5 (80%) required ICU care due to the severity of illness. Clinical complications included: sepsis 3/5 (50%), lung emboli 2/5 (40%), NSTEMI and new onset heart failure 1/5 (20%), altered mental status and psychosis 1/5 (20%). Klebsiella isolates were sequenced and 2/5 (40%) had the rmpA gene, and 5/5 isolates grown on agar exhibited hypermucoviscosity with a positive string test. Conclusion. Hypervirulent Klebsiella pneumoniae and severe invasive disease is of global concern with emerging incidence in North America. Further research is needed to elucidate risk factors for development. (Figure Presented).