Klebsiella pneumoniae is an encapsulated gram-negative bacillus that frequently causes outbreaks of nosocomial infections in hospitalized patients. K. pneumoniae can also afflict ambulatory persons and cause community-acquired invasive diseases—including pyogenic liver abscess, endophthalmitis, meningitis, empyema, lung abscess, and necrotizing fasciitis. The worldwide emergence of multidrug-resistant strains and hypervirulent strains of K. pneumoniae has become an increasing clinical challenge and public health concern. A new molecular diagnostic method based on detection of the genetic determinants of lipopolysaccharide (LPS) O-antigen has been developed by Dr. Chi-Tai Fang of National Taiwan University to rapidly and accurately identify hypervirulent K. pneumoniae O1 strains. This study was published in March 2016 in the Journal of Clinical Microbiology, a distinguished journal of the American Society for Microbiology. The research was conducted by Dr. Chi-Tai Fang, Professor of Epidemiology and Preventive Medicine at the College of Public Health, National Taiwan University, and his two Master’s students, Ms. Yun-Jui Shih and Ms. Cheng-Man Cheong. K. pneumoniae strains can be distinguished by their capsular polysaccharide (CPS) K-antigen types (77 serotypes) and LPS O-antigen types (9 serotypes). Strains with K1 CPS are extremely virulent, causing metastatic endophthalmitis and meningitis from pyogenic liver abscess. Nevertheless, only 60% of strains causing pyogenic liver abscess are K1 strains. The remaining strains are of K2, K5, K20, K54, K57, and other K types. On the other hand, more than 90% of strains causing pyogenic liver abscess have O1 LPSs. Therefore, O1 is a better marker for virulent K. pneumoniae strains capable of causing pyogenic liver abscess. However, previous research has not produced a simple and reliable method for detecting O1 in clinical and epidemiological samples because K. pneumoniae O-serotyping is cumbersome and the reagents are not commercially available. To develop a new molecular diagnostic method to quickly and accurately identify O1 K. pneumoniae, Dr. Fang and his students sequenced the genetic determinants of LPS O-antigen from O1, O2a, O2ac, O3, O4, O5, O8, O9, and O12 (Figure 1). They then successfully developed allele-specific PCR primers that detect the genes specific to O1 and other O types. His team further tested the sensitivity and specificity of the new molecular detection method against the O and K reference strains provided by the World Health Organization Collaborative Center for Escherichia coli and Klebsiella at Statens Serum Institut (Copenhagen, Denmark). Both the sensitivity and specificity were found to be 100%. Given the high accuracy and great convenience, the new PCR detection method represents an important breakthrough in the molecular diagnosis of hypervirulent K. pneumoniae. This new technology provides a highly useful tool for clinical and epidemiological investigations of K. pneumoniae and associated diseases. Reference Fang CT, Shih YJ, Cheong CW, Yi WC. Rapid and accurate determination of lipopoly-saccha¬ride O-antigen types in Klebsiella pneumoniae with a novel PCR-based O-genotyping method. J Clin Micro¬biol 2016; 54: 666-¬675. DOI: 10.1128/JCM.02494-15. Professor Chi-Tai Fang Institute of Epidemiology and Preventive Medicine fangct@ntu.edu.tw Figure Legend The two genetic determinants of lipopolysaccharide (LPS) O-antigen types in Klebsiella pneumoniae. Reference Chi-Tai Fang, Yun-Jui Shih, ChengMan Cheong, and Wen-Ching Yi. (2016). Rapid and accurate determination of lipopolysaccharide O-antigen types in Klebsiella pneumoniae with a novel PCRbased O-genotyping method. Journal of Clinical Microbiology, 54, 666-675. DOI: 10.1128/JCM.02494-15. Professor Chi-Tai Fang Institute of Epidemiology and Preventive Medicine fangct@ntu.edu.tw