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.

Our report emphasizes the importance of being aware of WE, even when patients do not present with delirium. The presence of loss of appetite for more than two weeks may be the key to a diagnosis of WE.

Clinicians must be aware of the possibility of Wernicke encephalopathy in cancer patients, especially in those with loss of appetite for longer than 18 days. The degree of appetite loss in such patients might serve as a reference. Early detection and intervention may alleviate the symptoms of delirium and prevent irreversible brain damage.

From a series of cancer patients, we reported three patients who developed TD without the typical clinical symptoms of WE.ResultA 69-year-old woman with pancreatic body cancer receiving chemotherapy with paclitaxel and gemcitabine for six months. Her performance status (PS) was 1. A detailed interview revealed that she had appetite loss for six months. Another 69-year-old woman with ovarian cancer received nedaplatin; her PS was 0. A detailed interview revealed that she had appetite loss for three months. A 67-year-old woman with colon cancer receiving ramucirumab in combination with second-line fluorouracil with folinic acid and irinotecan. Her PS was 1. A detailed interview revealed that she had appetite loss for three weeks. None exhibited typical clinical signs of WE, but they developed appetite loss for six months, three months, and three weeks, respectively. The diagnosis of TD was supported by abnormally low serum thiamine levels.Significance of the resultsThis report emphasizes the possibility of TD in cancer patients even when patients do not develop typical clinical signs of WE. The presence of appetite loss for more than two weeks may aid in diagnosing TD. Patients receiving chemotherapy may be at greater risk for developing TD.