Risk factors and outcomes of polymicrobial bacteremia involving K. pneumoniae in patients with IAI

Author(s):
Qinjie Liu; Jianan Ren; Jie Wu; Xiuwen Wu

Background:

Klebsiella pneumoniae have gained notoriety due to it’s high antibiotic resistance and mortality. Recent studys found that Polymicrobial bacteremia involving Staphylococcus aureus or Pseudomonas aeruginosa have been indicated with worse outcomes. However, there is no study to investigate the clinical significance of polymicrobial bacteremia involving K. pneumoniae (PBKP).

Hypothesis:

We hypothed that the clinical features and outcomes of PBKP is different from monomicrobial bacteremia involving K. pneumoniae.

Methods:

A retrospective observational study of patients with polymicrobial and monomicrobial bacteremia involving K. pneumoniae was performed from January 2012 to December 2016. Risk factors related to the PBKP and bacteremia-related mortality were analyzed. We compare the differences in expression of resistant genes (blaKPC, blaGES, blaOXA, blaVIM, blaNDM) and virulent genes (magA, Wzy, allS, rmpA, mrkD, wabG, entB, iroB, ybtS, iutA) of 27 strains of K. pneumoniae collected from the clinical study groups (10 from the polymicrobial group, 17 from the monomicrobial group) by Polymerase Chain Reaction (PCR).

Results:

The study included 47 (48.0%) patients with polymicrobial and 51 (52.0%) with monomicrobial bacteremia involving K. pneumoniae. The most common accompanying microorganism was E. coli in the polymicrobial group. There were no differences in expression of resistant genes and virulent genes between the two groups. As to outcomes, patients with PBKP were more likely have recurrent bloodstream infections (p=0.038), longer ICU length of stay (p=0.043) and higher total cost of hospitalization (p=0.045). However, there were no significant differences in bacteremia-related mortality or 7-day mortality between the two groups. In multivariate analysis, longer hospital stay before the onset of bacteremia (>20 days) is an independent risk factor for PBKP (p=0.034). Septic shock (p=0.023), inadequate source control (p=0.001) and iron supplementation (p=0.004) were independent predictors of bacteremia-related mortality in bacteremia involving K. pneumoniae patients.

Conclusions:

The development of septic shock and the concomitant use of iron supplementation are associated with higher bacteremia-related mortality in patients with KP bacteremia. PBKP did not increase mortality perhaps because the ability of K. pneumoniae to obscure the effects of other bacteria so that the adequate source control is more important than high-dose antibiotic therapy, which is linked with better survival.