Knowing the bacterial strains in the intensive care unit (ICU) is important for reducing the rate of bacterial transmission and the risk of healthcare-associated infections (HAIs), allowing for targeted interventions to reduce the risk of death by HAIs. We performed a retrospective case-control study in a single center that included 320 bacteriologically screened patients from the ICU of the Infectious Diseases Hospital in Constanta between September 2017 and March 2020. Sixty-five secondary bacterial infections were identified as the cause of hospital admission and 60 bacterial colonizations. There were 20 cases and 300 controls for the mortality rate and risk factors for death. Multivariate analysis identified that hospitalization of patients for HIV infection (OR 11.82, 95% CI: 1.69-83.62, P ≤0.05) and Clostridioides difficile infection (OR 7.38, 95% CI: 1.39 -39.22, P ≤ 0.05) were independent risk factors associated with death. We observed that the number of colonizations or secondary infections in the ICU was similar, and the mortality rate in the ICU was influenced by HIV infection or Clostridioides difficile infection.