A Retrospective Study On Molecular Characteristics, Risk Factors and Outcomes of Carbapenem-resistant Klebsiella pneumoniae bloodstream infections

Abstract Backgroud: Klebsiella pneumoniae (KP) is reported as the second most prevalent Gram-negative bacterium responsible for bloodstream infections (BSIs). In recent years, the management of BSIs caused by KP has become increasingly complex due to the emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP). Although numerous studies have explored the risk factors for the development of CRKP-BSIs, the mortality of patients with KP-BSIs, and the molecular epidemiological characteristics of CRKP, the variability in data across different populations, countries, and hospitals has led to inconsistent conclusions. Results: In our study, 134 patients with KP-BSIs were included; of these, 50 were infected with CRKP and 84 with carbapenem-susceptible Klebsiella pneumoniae (CSKP). The independent risk factors for CRKP-BSIs were identified as gastric catheterization (OR=9.143; CI=1.357-61.618; P=0.023), prior ICU hospitalization (OR=4.642; CI=1.312-16.422; P=0.017), and detection of CRKP in non-blood sites (OR=8.112; CI=2.130-30.894; P=0.002). Multivariate analysis revealed that microbiologic eradication beyond 6 days (OR=3.569; CI=1.119-11.387; P=0.032), high Pitt bacteremia score (OR=1.609; CI=1.226-2.111; P=0.001), and inappropriate empirical treatment after BSIs (OR=6.756; CI=1.922-23.753; P=0.003) were independent risk factors for 28-day mortality in KP-BSIs. The risk factor-based prediction model further confirmed that microbiologic eradication≥6.5 days and a Pitt bacteremia score of≥4.5 were significant predictive factors for 28-day mortality. Bioinformatics analysis identified ST11 as the predominant CRKP sequence type, with blaKPC-2 as the most prevalent gene variant. CRKP stains carried multiple plasmid-mediated resistance genes along with some virulence genes. Phylogenetic analysis indicated the presence of nosocomial transmission of ST11 CRKP within the ICU. Conclusions: The analysis of risk factors for developing CRKP-BSIs and the association between KP-BSIs and 28-day mortality, along with the development of a risk factor-based prediction model and the characterization of CRKP strains, enhances clinicians’ understanding of the pathogens responsible for BSIs. This comprehensive understanding may facilitate the timely administration of antibiotic therapy in patients suspected of having KP-BSIs, potentially improving patient outcomes.