Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM ObjectivesIn developing countries like India, the diagnosis of Pneumocystis jirovecii infection is often made either by conventional staining or clinically. This study was planned to know the utility of polymerase chain reaction (PCR) in diagnosing Pneumocystis jirovecii pneumonia (PJP), to compare the PCR results with that of the staining technique, and also to correlate the results with the radiological condition of patients from a tertiary care center in India.MethodA retrospective study included 3500 adult in-patients with symptoms of lower respiratory tract infection. Sputum and bronchoalveolar lavage samples were proceeded for both staining and PCR for multicopy mtLSU gene and singlecopy DHPS fas gene of P. jirovecii.ResultsThe present study was carried out in the Department of Microbiology, Max, Hospital, Saket, New Delhi, India. Between the years 2019 and 2022, the patients with clinically suspected pneumocystis pneumonia who attended outpatient or admitted to the Departments of Medicine, Gastroenterology, and Neurology, etc. of our hospital were retrospectively analyzed. The details of these patients were analyzed as per a well-structured proforma that included the detailed clinical history and laboratory data from the hospital records. A total of 3500 patients were included in the present study. Of these 3500 patients, 1.42% (50/3500) patients of pneumocystis pneumonia were confirmed, based on positivity by at least any two of the above-mentioned techniques. The age of the patients ranged from 29 to 80 years (mean 32 years). Among these 50 patients, 34 (68%) were males and 16 (32%) were females and the male-to-female ratio was 2:1. A total of 10 patients had human immunodeficiency virus (HIV) infection, while the other 25 were HIV negative. The immune status of five patients was unknown. Fever and dyspnea (n = 44, 88%), non-productive cough and abnormal auscultation sound (n = 30, 60%), and also chills and weight loss (n = 10, 20%) were the documented clinical symptoms of PJP. Radiological diagnosis of Pneumocystis pneumonia was noticed in 34 cases. Foamy alveolar casts were present in 19 cases. Silver methenamine stain enhanced the rounded, helmet, or cleft forms of sporozoites. Inflammatory infiltrate was mainly polymorphonuclear. All the cases were confirmed as P. jiroveci by PCR amplification.ConclusionClinicians often face the diagnostic dilemmas presented in the study. Individual modalities of the diagnosis are available, but all have drawbacks with varied sensitivity and specificity. Combining the available clinical, radiological, and microbiological modalities to reach early diagnosis can go a long way to avoid misdiagnosis and unnecessary delays in treatment.