Abstract: Objective The aim of this study was to investigate the pathogenic bacteria distribution and serum interferon-gamma (IFN-γ) and interleukin-6 (IL-6) level changes in patients with hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) complicated by bacterial infections. Methods 86 patients with HBV-ACLF were admitted to our hospital between December 2019 and January 2023, and the bacteria were isolated and identified routinely. Serum procalcitonin (PCT) level was detected by electrochemiluminescence immunoassay, and serum IFN-γ and IL-6 levels were assayed by ELISA. The diagnostic performance was evaluated by the area under the receiver operating characteristic (ROC) curve. Results 37 patients in our series were found having bacterial infection, and out of them, 68 pathogenic bacteria strains were characterized with Gram-negative bacteria infection in 41 strains and Gram-positive bacterial infection in 27 strains(39.7%); serum PCT, IFN-γ and IL-6 levels in patients with bacterial infection were (10.9±3.1)μg/L, (46.5±1.9)pg/mL and (16.9±1.6)pg/mL, all significantly higher [(0.9±0.1)μg/L, (20.1±2.4)pg/mL and (4.8±0.9)pg/mL, respectively, P＜0.05], and 28-day and 90-day fatality rates were 67.6% and 75.7%, both significantly higher than 8.2% and 12.2% (P＜0.05) in patients without bacterial infection; the ROC analysis showed that the AUC was 0.874, with the sensitivity of 93.6% and the specificity of 84.1%, when the combination of serum parameters was applied to predict bacterial infection as serum PCT＞3.3μg/L, serum IFN-γ＞45.5 pg/mL and IL-6＞15.4 pg/mL was set as the cut-off-value. Conclusion The distribution of pathogenic bacteria in patients with HBV-ACLF complicated by bacterial infections is characteristic, and the Gram-negative bacteria is the main common pathogenic bacteria. Besides serum PCT level, the surveillance of serum IFN-γ and IL-6 levels is helpful for early diagnosis of bacterial infection in this setting.

Key words: Acute-on-chronic liver failure, Bacterial infection, Procalcitonin, Interferon-gamma, Interleukin-6, Diagnosis