1318. Clinical and Molecular Characteristics of Hypermucoviscous Klebsiella pneumoniae Causing Pneumonia in Korea

BACKGROUND: Invasive Klebsiella pneumoniae (K. pneumoniae) was emerged in Asia, well-known for community-onset liver abscess. Healthcare-associated pneumonia caused by hypervirulent K. pneumoniae has been reported in recent studies. The purpose of this study was to evaluate the clinical and molecular characteristics of hypervirulent K. pneumoniae compared with classic K. pneumoniae in respiratory infection. METHODS: The study was performed on 163 K. pneumoniae isolates of respiratory infections collected from Keimyung University of Dongsan Medical Center from November 2013 to November 2015; group A, as classic K. pneumoniae and group B, as hypervirulent K. pneumoniae. Hypermucoviscous phenotype was confirmed with string test. Capsular serotypes, rmpA, magA, allS, mrkD, entB, kfu, and iutA were identified using specific primers by polymerase chain reaction. The biofilm mass was determined using the microtiter plate assay measured by optical density (OD, 570nm). RESULTS: A total 163 patients were analyzed, 100 (61.3%) of group A and 68 (38.7%) of group B. Community-acquired pneumonia was observed in 49.2% of group B and 18.0% of group A (p=0.001). Underlying diseases except chronic lung disease were more associated with group A. Mean age (72.6±11.7 vs. 68.8±12.5 years, p=0.051) and antimicrobial resistant rates were higher in group A. Mechanical ventilators (21.0% vs. 36.5%, p=0.030) was more associated with group B. Concordances of initial antibiotics (57.5% vs. 92.1%, p=0.001) were more observed in group B. Biofilm formation and infection related 30-day mortality showed no differences between the two groups. CONCLUSION: Contrary to our expectations, hypervirulent K. pneumoniae was more associated with community-acquired pneumonia in this study. Compared to classic K. pneumoniae, hypervirulent K. pneumoniae showed more association with severe pneumonia and less association with underlying diseases. In respiratory infection, biofilm formation was not different according to hypermucoviscousity. DISCLOSURES: All Authors: No reported disclosures