Retrospective study links CRKP pneumonia with higher mortality and microbial co-detections

A retrospective study of 158 patients with Klebsiella pneumoniae pulmonary infection found that the 81 patients with carbapenem-resistant K. pneumoniae (CRKP) had more microbial co-detections, greater use of mechanical ventilation, longer intensive-care stays and higher in-hospital mortality than the 77 patients with carbapenem-susceptible K. pneumoniae (CSKP). The study also evaluated metagenomic next-generation sequencing (mNGS) for detecting carbapenem-resistance genes and identified two laboratory markers associated with 28-day mortality among patients with CRKP. Researchers compared clinical data, laboratory findings and pathogen profiles in the two groups.

Their baseline characteristics were similar, but dyspnea was reported more often in the CRKP group, affecting 53.1% of patients compared with 35.1% of those with CSKP ( P = 0.034). CRKP patients also had a higher white blood cell count ( P = 0.035). The clearest differences involved acute resource use and outcomes: mechanical ventilation was significantly more frequent with CRKP ( P < 0.001), intensive-care stays were longer ( P = 0.001), and in-hospital mortality was 27.2% in the CRKP group versus 6.5% in the CSKP group ( P = 0.001).

These are retrospective group associations and do not show that carbapenem resistance itself caused the differences. The investigators used mNGS to characterize accompanying microorganisms and examine resistance genes in the clinical samples. Co-detection of additional microorganisms was significantly more common in patients with CRKP than in those with CSKP, occurring in 43.2% and 24.7% of the groups, respectively ( P = 0.022).

The difference was especially associated with Acinetobacter baumannii . For detecting carbapenem resistance, the mNGS results had an overall accuracy of 93.06% and a sensitivity of 87.65% relative to culture-based antimicrobial susceptibility testing. The bla KPC gene was the predominant resistance gene detected, with 72 cases.

The authors characterized mNGS as a complementary diagnostic strategy that can add resistance-gene information to conventional culture and susceptibility testing. To examine 28-day mortality within the CRKP cohort, the researchers used least absolute shrinkage and selection operator regression, followed by multivariable logistic regression, to identify independent statistical predictors. Fibrinogen was associated with lower odds of death, with an odds ratio of 0.45 ( P = 0.019).

Interleukin-6 was associated with higher odds, with an odds ratio of 1.08 for each 100-unit increase ( P = 0.036). These analyses position fibrinogen and IL-6 as accessible laboratory indicators that may help stratify short-term mortality risk in CRKP pulmonary infection, but the retrospective design does not establish causation or determine how well the markers perform in other populations. Taken together, the results portray CRKP pulmonary infection as being associated with a heavier acute-care burden than infection by susceptible strains.

The resistance-gene findings also show that mNGS detected a high proportion of carbapenem-resistance cases in this study, with bla KPC predominating. The study is limited by its retrospective design and its population of 158 patients, 81 of whom had CRKP, so the reported associations should be interpreted as observations within the analyzed cohort rather than universal effects of the organism or resistance phenotype.

Subject of Research: Clinical, microbiological and prognostic features of carbapenem-resistant Klebsiella pneumoniae pulmonary infection

Article Title: Clinical features, microbial co-detection profiles, and 28-day mortality of carbapenem-resistant Klebsiella pneumoniae pneumonia: a retrospective study with mNGS-based resistance gene detection

Article References: Liang, Y., Fu, X., Xu, H., Cui, L., Xing, Z., Ren, J., Xiao, H., Lv, P., & Hu, S. (2026). Clinical features, microbial co-detection profiles, and 28-day mortality of carbapenem-resistant Klebsiella pneumoniae pneumonia: a retrospective study with mNGS-based resistance gene detection. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14327-x

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14327-x

Keywords: CRKP, Klebsiella pneumoniae, pneumonia, metagenomic sequencing, carbapenem resistance, microbial co-detection, 28-day mortality, fibrinogen, interleukin-6, antimicrobial susceptibility, Clinical, features