Objective To explore the distribution characteristics of Klebsiella pneumoniae T6SS in bloodstream infections in elderly patients and its correlation with strain resistance, virulence genes and clinical risk factors, and provide basis for clinical diagnosis and treatment and prevention and control strategies.Methods Seventy non-repeatable Klebsiella pneumoniae strains from blood specimen sources of elderly patients in our hospital from January to December 2023 and related clinical data were collected, and microbial identification and drug sensitivity tests were performed using VITEK MS and VITEKR2Compact, mucus phenotype was detected by pulling assay. PCR methods were used for detecting the T6SS genes (hcp, icmF, vgrG) and virulence genes (rmpA, rmpA2, iroB, iucA, peg344). The multifactorial logistic regression was used to analyze the independent risk factors for the occurrence of bloodstream infections with T6SS-positive Klebsiella pneumoniae in elderly patients.Results Among 70 strains of Klebsiella pneumoniae infecting bloodstream in elderly patients, T6SS-positive strains accounted for 22-86% (16/70). Compared with T6SS-negative strains, T6SS-positive strains were more sensitive to commonly used antimicrobial drugs. 81-25% (13/16) of T6SS-positive strains had a high mucus phenotype and 56-25% (9/16) of high-virulence strains were higher than those of T6SS-negative strains, and the difference was statistically significant (P<0-05). 5 virulence genes of T6SS-positive strains (rmpA, rmpA2, iroB, iucA, peg344) were detected at higher rates than T6SS-negative strains, and the differences were statistically significant (P<0-05). Multifactorial logistic regression analysis suggested that community-acquired infections (OR=8-20), diabetes mellitus (OR=3-50), hepatobiliary diseases (OR=5-03), admission to the ICU (OR=10-29), and increased inflammatory markers (leukocyte count OR=1-05, neutrophil percentage OR=1-03, and C-reactive protein OR=1-02) were the main factors in the elderly patients with T6SS-positive Klebsiella pneumoniae as independent risk factors for developing bloodstream infections. Conclusion T6SS-positive Klebsiella pneumoniae is more common in elderly patients with bloodstream infections. T6SS-positive strains have the characteristics of “low drug resistance and high virulence”. Community-acquired infections, diabetes mellitus, liver and biliary diseases, admission to the ICU, and increased inflammatory indexes are the independent risk factors for the occurrence of bloodstream infections with T6SS-positive Klebsiella pneumoniae in elderly patients