The frequency and clinical features of posttransplant pneumonia in solid-organ transplantation recipients: A transplant center experience.

Introduction: In solid-organ transplant (SOT) recipients, while survival rates have improved with immunosuppressive therapies, the risk of opportunistic infections has also increased. This study aimed to evaluate the frequency of pneumonia, identify microbiological factors, investigate diagnostic methods, and analyse prognosis. Materials and Methods: A retrospective study was conducted to identify adult SOT recipients referred to the pulmonary diseases department with a preliminary pneumonia diagnosis between 2011 and 2019. Data on demographics, clinical and transplantation characteristics, pneumonia frequency, microbiological sampling methods, pathogens, radiological findings, and prognosis were collected. Confirmed pneumonia was defined as symptoms consistent with pneumonia alongside microbiological confirmation. Result: We conducted 426 pulmonary consultations involving 168 patients (86 kidney; 82 liver transplant recipients) with a preliminary pneumonia diagnosis. Pneumonia was diagnosed in 87% of the cases, with common findings including multiple symptoms, glucocorticoid use, focal or multilobar infiltrations, and diffuse ground-glass nodules. Pneumonia frequency was higher during the first, sixth, and twelfth months for liver transplants and after twelve months for kidney transplants. Diagnostic sampling was conducted for 128 patients, with a success rate of 63.3%. Of 476 respiratory samples, 32.6% yielded diagnoses, with bacterial growth detected in 42.9%, predominantly Pseudomonas aeruginosa. Microbiological agents were isolated by 18.4% using non-invasive methods, 15.5% using invasive methods. Non-invasive methods primarily isolated gram-positive and gram-negative bacteria, Acinetobacter spp., Klebsiella spp., Haemophilus spp., whereas invasive methods were more effective for Candida spp. Acinetobacter spp. was more prevalent in liver transplant patients and fungal species in kidney transplant patients. Intensive care unit admission occurred in 36.3% of the patients, 19% died. Conclusions: : While pneumonia was common among SOT recipients, the associated mortality rate was relatively low. Over half the patients were diagnosed through microbiological sampling. Invasive sampling is valuable for non-bacterial agents. Due to high gramnegative bacteria frequency and early post-transplant pneumonia, increased attention is needed for hospital-acquired agents.