Immune imbalance markers: key factors in early recognition of multidrug-resistant bacterial infections in non-immunocompromised VAP patients.

BACKGROUND

Research on the role of immune dysregulation in multidrug-resistant organism (MDRO) infections among patients with ventilator-associated pneumonia (VAP) remains limited, and there is a lack of reliable immunological indicators for early identification.

METHODS

We conducted a retrospective analysis of 247 non-immunocompromised patients who developed VAP following mechanical ventilation in the Neurointensive Care Unit (NICU). Patients were categorized into MDRO and non-MDRO groups based on the presence or absence of MDRO infection. Binary logistic regression with sequential adjustment (three models), subgroup analyses, and receiver operating characteristic (ROC) curve analysis were used to evaluate associations between MDRO infection and early-stage (within 72 hours) immunological indicators, including IL-10, IL-17A, IL-6, and T-cell parameters (CD4+, CD8+, CD3+ counts, and CD4/CD8 ratio). Additionally, six pathogen-specific subgroups were analyzed to assess differences in immune factor levels across pathogen types.

RESULT: In univariate analysis, T-cell parameters showed no statistical significance, but IL-10 and IL-6 levels were significantly elevated in the MDRO group. In the fully adjusted logistic regression model, IL-10 and IL-6 were identified as independent risk factors. Higher IL-10 tertiles showed a dose-response relationship with MDRO risk. Subgroup analysis indicated that elevated IL-10 and IL-6 increased MDRO risk in patients with albumin ≥30 g/L. ROC analysis demonstrated good diagnostic performance for IL-10, IL-6, and their combined model (IL-10+IL-6). Serum IL-6 levels were significantly higher in patients with extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-KP) infection than in those with carbapenem-resistant Acinetobacter baumannii (CRAB) infection, indicating pathogen specificity. In contrast, IL-10 levels did not differ significantly across MDRO subgroups (CRAB, ESBL-KP, CRPA, and mixed infection), suggesting a universal host immune response to MDRO infection.

CONCLUSIONS

Within 72 hours after VAP onset, elevated serum IL-10 and IL-6 levels are an immune dysregulation state resulting from multiple immune factor imbalance mechanisms, which may facilitate early identification of patients at risk for MDRO infection, with serum IL-10 levels showing potential value as an independent biomarker. Serum IL-10 levels may sensitively reflect the host's immune dysregulation status, whereas serum IL-6 levels may indicate a specific immune response to a certain MDRO strain.