Clinical characteristics in blood stream infections caused by Klebsiella pneumoniae, Klebsiella variicola, and Klebsiella quasipneumoniae: a comparative study, Japan, 2014–2017

Abstract

BackgroundKlebsiella variicola and K. quasipneumoniae are new species distinguishable from K. pneumoniae but they are often misidentified as K. pneumoniae in clinical settings. Several reports have demonstrated the possibility that the virulence factors and clinical features differ among these three phylogroups. In this study, we aimed to clarify whether there were differences in clinical and bacterial features between the three phylogroups isolated from patients with bloodstream infections (BSIs) in Japan.MethodsIsolates from all patients with BSIs caused by K. pneumoniae admitted to two hospitals between 2014 and 2017 (n = 119) were included in the study. Bacterial species were identified via sequence analysis, and their virulence factors and serotypes were analyzed via multiplex PCR results. Clinical data were retrieved from medical records.ResultsOf the 119 isolates, 21 (17.7%) were identified as K. variicola and 11 (9.2%) as K. quasipneumoniae; K1 serotype was found in 16 (13.4%), and K2 serotype in 13 (10.9%). Significant differences in the prevalence of rmpA, iutA, ybtS, entB and kfu (p < 0.001), and allS genes (p < 0.05) were found between the three phylogroups. However, there were no significant differences in clinical features, including the 30-day mortality rate, between the three organisms, although K. variicola was more frequently detected in patients over 80 years old compared with other Klebsiella species (p < 0.005), and K. quasipneumoniae more frequently occurred in patients with malignancy (p < 0.05).ConclusionsOur findings demonstrated the differences in bacterial pathogenicity and clinical features among these three phylogroups. Further epidemiological studies into BSI caused by Klebsiella species are warranted.

Forensic genomics of a novel Klebsiella quasipneumoniae type from a neonatal intensive care unit in China reveals patterns of colonization, evolution and epidemiology

“…While K. quasipneumoniae subsp. similipneumoniae has been less widely reported and discussed than K. pneumoniae, similar to our investigation, there has been an increased recognition of K. quasipneumoniae subspecies in hospital surveys and their association with resistance genes [57,58], indicating that a comprehensive assessment of their role in AMR ecology and contribution to disease burden is required. Their underrecognition is also due to the mis-assignment of non-K. pneumoniae strains to the type species.…”

Isolation and Characterization of Two Klebsiella pneumoniae Phages Encoding Divergent Depolymerases

“…Due to the high heterogeneity of K. pneumoniae, it often becomes difficult to determine the virulence factors of this species [7]. Nevertheless, the capsule of K. pneumoniae is one such virulence factor, and hypervirulence has been associated with differences in the expression of genes involved in the capsule, or with modified capsule phenotypes [8].…”

Klebsiella variicola causing nosocomial transmission among neonates – an emerging pathogen?

“…Imai and colleagues recently reported that among 119 isolates obtained from patients with blood stream infection conventionally identified as K. pneumoniae, 21 isolates (17.7 %) were in fact K.variicola on further molecular analysis, five of which were ESBL-producers. However, there were no significant differences in clinical features, including 30-day mortality between the organisms [16]. In a recent study, Potter and colleagues reported pathogenicity of K. variicola in a murine model ofurinary tract infection [17].…”