Staphylococcus aureus infections in a highly complex clinic in Colombia. A longitudinal retrospective observational study.

Background: Antimicrobial resistance is a public health problem. Methicillin-resistant Staphylococcus aureus (MRSA) is one of the microorganisms most responsible for illness and death. The aim was to characterize the infections caused by S. aureus and to determine the factors associated with in-hospital mortality in patients treated in a highly complex clinic in Colombia.

Methods: This was a longitudinal retrospective observational study of patients with culture-confirmed S. aureus infections who received hospital care between 2018 and 2023. Follow-up was carried out until the patients died or were discharged from the clinic. Descriptive, bivariate and multivariate analysis was performed.

Results: A total of 361 patients were included; 62.6 % were men, and the mean age was 49.2 years. Most patients were diagnosed with skin and soft tissue infections (51.0 %) and bacteremia (25.5 %). The most used antibiotics were clindamycin (53.5 %) and vancomycin (42.7 %). A total of 46.3 % had MRSA infections and 25.8 % were resistant to clindamycin, 37.7 % of the patients received care in the intensive care unit, 33.2 % had sepsis, 19.1 % required invasive mechanical ventilation, and 13.9 % died. Higher Charlson comorbidity index (aOR:1.45; 95%CI:1.04-2.02), higher Pitt Bacteremia Score (aOR:1,72; 95%CI:1.21-2.46) and bacteremia (aOR:5.30; 95%CI:1.44-19.41) increased the probability of death. Those who were empirically managed with antibiotics that had coverage for MRSA (aOR:0.03; 95%CI:0.00-0.24) and higher levels of hemoglobin (aOR:0.75; 95%CI:0.65-0.87) had a lower risk of death.

Conclusion: MRSA infections are frequent, with significant resistance to clindamycin. The identification of variables associated with a higher risk of dying may be useful for establishing protocols in hospitals that reduce this outcome.