Clinical Characteristics and Diagnostic Approaches in Paediatric <i>Pneumocystis jirovecii</i> Pneumonia: A Focus on Gastric Aspirate Samples

Abstract

Background: Pneumocystis pneumonia (PCP) typically affects immunocompromised children, including those with HIV infection, those receiving cancer treatment, and those who have undergone transplantation. However, it also affects children from socioeconomically disadvantaged backgrounds. Objectives: This retrospective single center study aimed to describe the clinical characteristics of a cohort of paediatric patients with suspected PCP and to evaluate the clinical feasibility and diagnostic contribution of different sample types. Methods: Eligibility criteria included all paediatric patients presenting with clinical signs of pneumonia who underwent diagnostic testing for P. jirovecii based on clinical suspicion. Participant selection was based on a review of electronic and written medical records. This study specifically focused on the use of gastric aspirates, which were the most frequently collected samples in this population. A total of 277 patients between November 2017 and September 2024 underwent diagnostic tests, including real-time PCR analysis of laryngeal swabs, sputum, bronchoalveolar lavage, gastric aspirates, and pleural effusion. The study utilized descriptive statistics (frequencies, percentages, median, range) to summarize data; formal analytical statistical tests were not performed given the study's descriptive nature. Data on clinical outcomes were collected from medical records documenting patient follow-up post-treatment. Results: The diagnosis of PCP was confirmed in 36 patients (13%), ranging from 2 months to 2.5 years old, with 31 cases (86%) occurring in infants under 12 months. In our cohort, the diagnosis was most frequently established from gastric aspirates, which accounted for 29 of the 36 positive cases (80%), followed by bronchoalveolar lavage (8%), laryngeal swabs (6%), and sputum (6%). The predominant clinical presentation was prolonged respiratory deterioration with chronic cough and persistent refractory bronchoconstriction in 29 patients (81%). Fourteen patients (39%) experienced acute respiratory distress syndrome (RDS) and required additional oxygen and systemic corticosteroid therapy. Following appropriate treatment, clinical improvement, resolution of bronchial obstruction, and nutritional recovery were achieved. In the cohort of RT-PCR-positive cases, characteristics such as low socioeconomic status, malnutrition, poor sanitation, and exposure to tobacco smoke and combustion fumes were frequently observed, all of which are potential confounders or effect modifiers that may contribute to secondary immunodeficiency. Conclusions: The study's retrospective, single-centre design is subject to inherent limitations, such as potential selection bias. Although bronchoalveolar lavage is the ideal diagnostic method, its acquisition can be challenging in critically ill young infants. Our findings highlight the clinical utility of gastric aspirates as a valuable, minimally invasive alternative for diagnosing PCP in this vulnerable population.