The Emerging Infections Network (EIN) is a forum for infectious diseases consultants and public health officials to report information on clinical phenomena and epidemiological issues with public health significance. Any diagnostic or therapeutic recommendations and all opinions presented are those of the individual contributor. They do not necessarily represent the views of EIN, IDSA (EIN’s sponsor), or the Centers for Disease Control and Prevention (CDC), which funds EIN. The reader assumes all risks in using this information.
The EIN goals include helping to connect members to the CDC and other public health investigators, and developing new methods for gathering epidemiological and clinical information, as in this recent case involving an investigator who is hoping to develop a better diagnostic test for Klebsiella pneumoniae (hvKp).
Recently an EIN member posted a case of hypervirulent (hypermucoviscous) hvKp in a patient without epidemiological links to Southeast Asia and asked how often others were seeing this entity in the U.S. Several respondents reported also seeing hvKp in patients without epidemiological links to Asia, and also that their clinical laboratories did not routinely assess for a hypermucoviscous phenotype without special requests from the clinicians involved or were not sure how to do this.
About six weeks later, the same member sent follow-up information to the EIN listserv, indicating that he had been contacted by a physician-scientist who investigates hvKp. This investigator is interested in developing diagnostic tests for the clinical microbiology lab to reliably identify hvKp. To accomplish this he would like to add more strains to his collection that have a clinical history consistent with hvKp infection.
The investigator, Dr. Thomas Russo of the University of Buffalo, characterized hvKp as an emerging variant (pathotype) of Klebsiella pneumoniae that was first recognized in Taiwan in 1986. hvKp infection initially was characterized and distinguished from traditional infections by (1) presentation as community-acquired pyogenic liver abscess, (2) occurrence in patients lacking a history of hepatobiliary disease, and (3) a propensity for metastatic spread to distant sites (e.g., eyes, central nervous system, lungs). More recently, this variant has been recognized to also cause a variety of serious, community-acquired non-hepatic abscesses/infections, including pneumonia, meningitis, endophthalmitis, splenic abscess, and necrotizing fasciitis. The affected individuals often have diabetes mellitus and are of Asian descent; however, non-diabetics and all ethnic groups can be affected.
There is currently no way to reliably identify hvKp. The “string test,” which tests for the hypermucovisvous phenotype, is not typically performed. Further, the string test has a subjective component, its sensitivity and specificity for hvKp strains has not been defined, and importantly classic K. pneumoniae strains may also be string test positive, which is particularly problematic in areas of low hvKp prevalence.
Dr. Russo believes that the development of a more objective diagnostic test will enhance researchers’ ability to perform more comprehensive epidemiologic studies. It will also enable the full spectrum of infectious syndromes and the incidence of infection to be defined, especially outside of the Asian Pacific Rim. He also notes that a better test will assist the clinician in disease management, as the knowledge that an hvKp strain is causing infection should prompt a search for concomitant or subsequent metastatic sites of infection (e.g. eye or CNS), which may require drainage or a site-driven modification of the antimicrobial regimen. Anecdotal data suggests that hvKp reinfection or relapse may develop months to years after treatment has been completed; thereby long-term follow-up may be necessary. A more objective diagnostic test will enable studies on whether the nature and duration of therapy for hvKp infection should be different, he says.
“Our laboratory is in the process of trying to develop an objective test(s) that could be used to distinguish classic from hvKp strains,” Dr. Russo says. “To achieve this goal we would like to increase our collection of hvKp isolates.” He is interested in hearing from clinicians who are aware of a potential case of hvKp infection and the isolate is available for further study. To contact Dr. Russo, email firstname.lastname@example.org or call (716) 829-2674.
Note: EIN does not collect either the samples or any patient identifiers, but rather serves as a “matchmaker” to connect the clinician with the investigator as it did in this case.
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