Survey of Klebsiella pneumoniae bacteraemia in two South Australian hospitals and detection of hypermucoviscous phenotype and magA/rmpA genotypes in K . pneumoniae isolates

Abstract

Clinical patterns of Klebsiella pneumoniae bacteraemia vary geographically. An invasive syndrome involving abscess formation has emerged in recent years. Putative virulence factors associated with this syndrome include colony hypermucoviscosity, and magA and rmpA genes. We studied epidemiologic and microbiologic characteristics of K. pneumoniae bacteraemia at two South Australian hospitals and identified cases of K. pneumoniae invasive syndrome. We determined the frequency of the hypermucoviscosity, magA and rmpA genes among bacteraemic and selected non-bacteraemic isolates. Thirty-one patients with K. pneumoniae bacteraemia treated between June 2010 and July 2011 were included. Existing records were examined for relevant clinical and microbiological data. Urinary and wound isolates were also examined. Hypermucoviscosity was identified by a positive string test, whilst polymerase chain reaction detected magA and rmpA positive isolates. Of 31 blood culture isolates, 22 were associated with community-acquired infection. Biliary infection was the commonest source, occurring in ten patients. Three patients had K. pneumoniae invasive syndrome, all of Asian extraction (p = 0.0044). Four blood isolates demonstrated one or more of hypermucoviscosity, magA or rmpA; three were from patients with liver abscesses. Liver abscess isolates were all K1 serotype and had similar PFGE profiles. This study augments understanding of local epidemiology and microbiology of K. pneumoniae bacteraemia. It confirms local emergence of K. pneumoniae invasive syndrome and implicates the role of magA and rmpA genes in its pathogenesis.