Epidemiology and risk factors of multidrug-resistant organisms in a Chinese tertiary hospital: a 10-year retrospective cohort study across the COVID-19 policy phases, 2013-2023.

BACKGROUND

Multidrug-resistant organism (MDRO) infections are a major global health threat. The COVID-19 pandemic and related containment policies may have altered hospital infection epidemiology and the distribution of MDROs.

METHODS

In this retrospective cohort study, clinical and microbiological data from 2,669 adult inpatients with culture-confirmed hospital-acquired infections between 2013 and 2023 were analyzed. MDROs were defined per CLSI guidelines. The study period was stratified into pre-pandemic, strict containment, and post-adjustment phases. Multivariate logistic regression was used to identified factors associated with specific MDRO infections.

RESULTS

The overall MDRO detection rate increased from 36.9% to 56.4% during the strict containment. CRAB, which had previously been the dominant resistant pathogen, was progressively overtaken by CRE, while Klebsiella pneumoniae became the predominant species in 2022 (40.0%).Bloodstream infections increased from a pre-pandemic peak of 24% to 32% during the strict containment phase. Male sex, age≥60 years, and prolonged hospitalization (>14 days) were associated with distinct distribution patterns of CRAB and CRE infection. In multivariable analyses, mechanical ventilation was associated with increased odds of CRAB infection (aOR=2.07, 95% CI: 1.36-3.16), while urinary catheter use was associated with increased odds of CRE infection (aOR=1.49, 95% CI: 1.06-2.09) but lower odds of CRAB infection (aOR=0.64, 95% CI: 0.46-0.89). Endotracheal intubation was associated with increased odds of VRE infection (aOR = 5.84, 95% CI: 1.10-30.9).

CONCLUSIONS

Hospital MDRO epidemiology shifted substantially across the COVID-19 policy phases, with CRE emerging as the dominant resistant pathogen. Specific invasive procedures showed pathogen-specific associations, supporting risk stratification and more targeted infection prevention strategies in high-risk hospitalized patients.