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The Case Report of Klebsiella quasipneumoniae subsp. similipneumoniae ST138-K1/O5 in a Clinically Vulnerable Patient

Year: 2026

Type: article

Abstract: Emerging pathogens are a great threat to healthcare systems, with Klebsiella pneumoniae species complex (KpSC) infections are challenging. Members of the KpSC are frequently identified as K. pneumoniae by conventional automated or proteomic systems. The aim of this study was to characterize a KpSC isolate obtained from a patient with sepsis and liver disease, describing their clinical features. The patient’s clinical data were obtained from her medical history. Identification and antibiotic susceptibility testing were performed with different approaches. Whole Genome Sequencing (WGS) was conducted, in silico analysis using available databases was undertaken to predict antibiotic resistance determinants, plasmid incompatibility groups, sequence type (ST), capsular K-type, O-antigen and virulence genes. From blood cultures grew a K. pneumoniae isolate (K87), characterized as K. quasipneumoniae subsp. similipneumoniae by WGS. K87 belongs to ST138-K1/O5 serotype and harbours blaOKP-B-2 gene. Virulome included type III fimbriae, ferric iron uptake systems and metabolic functions. After months of hospitalization, the patient showed clinical deterioration and, despite appropriate antibiotic treatment, died. This is the first report of bacteremia and liver disease associated with a Klebsiella quasipneumoniae subsp. similipneumoniae ST138-K1/O5 isolate. The ongoing emergence of KpSC pathogens in healthcare settings underscores the critical need for continuous surveillance with molecular characterization.

Source: Microorganisms

DOI: 10.3390/microorganisms14102357