Clinical characteristics, risk factors and outcomes of Klebsiella pneumoniae pneumonia developing secondary Klebsiella pneumoniae bloodstream infection

Purpose

The clinical characteristics of Klebsiella pneumoniae (KP) pneumonia and KP bloodstream infection (KP-BSI) are often reported, while the risk factors for KP pneumonia developing into secondary KP-BSI (KP-pneumonia/KP-BSI) are largely unknown. Therefore, this study attempted to investigate the clinical characteristics, risk factors and outcomes of KP-pneumonia/KP-BSI.

Methods

A retrospective observational study was conducted at a tertiary hospital between January 1, 2018, and December 31, 2020. The patients were divided into groups of KP pneumonia alone and KP pneumonia/KP-BSI, and the clinical information were collected from medical records electronic system.

Results

A total of 409 patients were finally recruited. According to the multivariate logistic regression analysis, male sex (adjusted odds ratio [aOR] 3.7; 95% CI, 1.44–9.5), immunosuppression (aOR, 13.52; 95% CI, 2.53,72.22), APACHE II score higher than 21 (aOR, 3.39; 95% CI, 1.41–8.12), serum procalcitonin (PCT) levels above 1.8 ng/ml (aOR, 6.37; 95% CI, 2.67–15.27), ICU stay of more than 2.5 days before pneumonia onset (aOR, 1.09; 95% CI, 1.02,1.17), mechanical ventilation (aOR, 4.96; 95% CI, 1.2,20.5), Klebsiella pneumoniae isolates producing extended spectrum β-lactamase (ESBL-positive KP) (aOR, 12.93; 95% CI, 5.26–31.76), and inappropriate antibacterial therapy (aOR, 12.38; 95% CI, 5.36–28.58) were independent factors of KP pneumonia/KP BSI. In comparison with the patients with KP pneumonia alone, the patients with KP pneumonia/KP BSI showed an almost 3 times higher incidence of septic shock (64.4% vs. 20.1%, p < 0.01), a longer duration of mechanical ventilation, and longer lengths of ICU stay and total hospital stay (median days, 15 vs. 4,19 vs. 6, 34 vs. 17, respectively, both p < 0.01). Additionally, the overall in-hospital crude mortality rate in the patients with KP-pneumonia/KP-BSI was more than two times higher than that in those with KP pneumonia alone (61.5% vs. 27.4%, p < 0.01).

Conclusion

Factors including male sex, immunosuppression, APACHE II score higher than 21, serum PCT levels above 1.8 ng/ml, ICU stay of more than 2.5 days before pneumonia onset, mechanical ventilation, ESBL-positive KP, and inappropriate antibacterial therapy are independent risk factors for KP pneumonia/KP-BSI. Of note, the outcomes in patients with KP pneumonia worsen once they develop secondary KP-BSI, which merits more attention.

Klebsiella pneumoniae presents antimicrobial drug resistance for β-lactam through the ESBL/PBP signaling pathway

Overuse and misuse of antibiotics leads to antibiotic resistance which has become a significant public health concern. Klebsiella pneumoniae is the most common pathogenic bacteria underlying nosocomial infections due to the expression of virulence factors and occurrence of antibiotic resistance. Evidence indicates that β-lactamase is involved in the antibiotic resistance of Klebsiella pneumoniae to β-lactam antibiotics. The aim of the present study was to investigate the association between the molecular biological mechanisms of antibiotic resistance of Klebsiella pneumoniae and extended-spectrum β-lactamase (ESBL). In order to assess temporal trends in prevalence and antimicrobial susceptibility, Klebsiella pneumoniae bacteria were isolated and the ESBL expression level was analyzed. Susceptibility tests were performed using automated systems. The β-lactam-resistance in Klebsiella pneumoniae was assessed by the β-lactam agar screen plate and respective MIC values were evaluated using E-test strips. The confirmatory disk diffusion methods were applied for phenotypic identification of the ESBL production of Klebsiella pneumoniae. The results showed that Klebsiella pneumoniae bacteria exhibited higher ESBL production after treatment with β-lactam compared to the control. The ESBL gene expression was upregulated in Klebsiella pneumoniae after treatment with β-lactam. Results identified that penicillin-binding proteins (PBPs) were associated with the growth and resistance to β-lactams. Zinc finger nuclease markedly inhibited the antibiotic resistance of Klebsiella pneumoniae to β-lactam. PBP knockdown abolished the inhibitory effects of zinc finger nuclease on the growth of Klebsiella pneumoniae induced by β-lactam antibiotic treatment. In conclusion, these results suggest that the resistance of Klebsiella pneumoniae bacteria to antimicrobial drugs is through the ESBL signaling pathway, which indicates that ESBL may be a potential target for abolishing resistance to β-lactam.