[Adequacy to diagnostic recommendations in patients with Pneumocystis jirovecii pneumonia treated with intravenous pentamidine].

Objective: To determine the rate of microbiological confirmation in the diagnosis of Pneumocystis jirovecii pneumonia in patients treated with intravenous pentamidine and the potential correlation with treatment effectiveness and safety.

Methods: Single-centre retrospective study (2010-2020), which included those patients who received intravenous pentamidine treatment for at least 48 hours. The sample collection procedure and the microbiological analysis performed were recorded. Efficacy was determined by 14-day mortality rate and admission to the Intensive Care Unit (ICU), and disease control was determined by length of hospital stay and time from completion of treatment to discharge. The safety profile was assessed according to the Common Terminology Criteria for Adverse Events (CTCAE) v5.0.

Results: A total of 17 patients with P. jirovecii pneumonia were treated with pentamidine (76.5% male (n=13); mean age [standard deviation]: 58.6 [15.5]). Microbiological confirmation of the pathogen was established in 47.1% (n=8) of cases. Targeted use of pentamidine significantly reduced the time from treatment completion to hospital discharge (p=0.019). The safety profile was acceptable, with grade I toxicity occurring in one patient.

Conclusions: The study shows that more than 50% of patients receive treatment based on a presumptive diagnosis and without adhering to the established recommendations, with repercussions on the duration of admission and recovery of the patient. Future studies with a larger sample size will be necessary to consolidate the results obtained.