Getting hypervirulent Klebsiella pneumoniae on the radar screen.

PURPOSE OF REVIEW: Two pathotypes of Klebsiella pneumoniae cause human infections, classical (cKp) and hypervirulent (hvKp) K. pneumoniae. The present understanding of genetic elements, the need for an accurate test to identify hvKp, the clinical implications of infection, the knowledge gap on how and why hvKp colonization transitions to infection, and potential infection prevention and control issues for hvKp are discussed.

RECENT FINDINGS: Infections because of hvKp are increasingly recognized worldwide. Its ability to cause organ and life-threatening disease in healthy individuals from the community merits concern, which has been magnified by increasing descriptions of multiply drug-resistant (MDR) and extensively drug-resistant (XDR) strains. Increased capsule and siderophore production by hvKp relative to cKp are critical virulence traits. Asians are most commonly infected, but whether this is mediated by a genetic susceptibility, or increased exposure and colonization is unknown. Specific studies about the epidemiology and transmission of hvKp are lacking, but precautions are appropriate for MDR/XDR strains and perhaps all infected/colonized individuals.

SUMMARY: hvKp is evolving into an increasingly concerning pathogen, in part because of the development of XDR strains. An accurate test to identify hvKp is needed for optimal clinical care, epidemiological, and research studies. An improved understanding of how infection develops, if a genetic susceptibility exists, and appropriate infection prevention and control measures also are needed.