Susceptibility profile of Acinetobacter baumannii and Pseudomonas aeruginosa isolated from hospitalized patients: Retrospective study and pharmacokinetic/pharmacodynamic modeling of antibiotic therapy.

Background: Acinetobacter baumannii and Pseudomonas aeruginosa stand out for their resistance to last-line antibiotics. This study aims to assess the outcome and the susceptibility profile and to verify the therapeutic regimens by pharmacokinetic/pharmacodynamic modeling.

Methods: A retrospective study involved clinical variables and antibiotic use of 121 patients attended from January to December 2023. Monte Carlo simulations were applied to simulate pharmacokinetics and pharmacodynamics of β-lactam antibiotics.

Results: A baumannii (n = 39) was associated with higher mortality (76.9%) and identified as a predictor for death (P = .006). Infections detected in tracheal aspirates (n = 65) increased chances of death (P = .014), as hospitalization in intensive care unit (n = 60) (P = .002). Among the isolates, 49.6% showed antimicrobial resistance, being a predictive factor for death (P = .034). No β-lactam antibiotic reached the ideal cumulative response fraction.

Discussion: Monte Carlo simulations showed that current regimens have limited efficacy for the observed resistance profile. The failure of therapeutic regimens to be effective reflects the urgent need to re-evaluate hospital protocols and strategies to contain antimicrobial resistance.

Conclusions: A baumannii infections were associated with intensive care and ventilator-associated pneumonia, as well as high resistance to carbapenems.