Polymicrobial Bacteremia Involving Klebsiella pneumoniae in Patients with Complicated Intra-Abdominal Infections: Frequency, Co-Pathogens, Risk Factors, and Clinical Outcomes

Background: Klebsiella pneumoniae has gained notoriety because of its high antibiotic resistance and mortality. We compared the clinical features and outcomes of polymicrobial bacteremia involving K. pneumoniae (PBKP). Patients and Methods: A retrospective observational study of patients with polymicrobial and monomicrobial bacteremia involving K. pneumoniae from January 2012 to December 2016 was performed. The expression of resistance and virulence genes of 27 strains was also compared by polymerase chain reaction (PCR). Results: Among the polymicrobial group, the most common accompanying micro-organism was Escherichia coli. No differences in the expression of resistance and virulence genes was found among the 27 strains collected from the group. The analysis of the outcomes revealed that the patients with PBKP were more likely to have recurrent blood stream infections (p = 0.038), longer intensive care unit (ICU) lengths of stay (p = 0.043), and a higher total hospitalization cost (p = 0.045). However, no substantial differences in mortality were found between the two groups. The multivariable analysis revealed that a longer hospital stay prior to the onset of bacteremia (>20 days) was an independent risk factor for PBKP (p = 0.034), and the Sequential Organ Failure Assessment (SOFA) score upon onset of infection (p = 0.013), the adequacy of source control (p < 0.001), and iron supplementation (p = 0.003) were identified as independent predictors of mortality in patients with KP bacteremia. Conclusions: The development of septic shock and the concomitant use of iron supplementation are associated with higher mortality in patients with KP bacteremia, and PBKP did not increase the mortality of these patients, possibly because of the ability of K. pneumoniae to obscure the effects of other bacteria. Thus, adequate source control is more important than high-dose antibiotic therapy and is linked to higher survival.