Spectrum of pulmonary infections in renal transplant recipients in the tropics: a single center study

Abstract

Background: Pulmonary infections have been implicated as the most common cause of infection related mortality in renal transplant recipients. An appropriate empirical treatment of post transplant pulmonary infections requires knowledge of the spectrum of the microorganisms involved in causing these infections. Besides this knowledge, an aggressive diagnostic approach including the use of invasive tests is often essential to make an early diagnosis for instituting timely and appropriate therapy. We carried out a prospective cohort study to analyze the spectrum of pulmonary infections in these patients and study the utility of bronchoalveolar lavage (BAL) in the diagnosis of the same.

Methods: From September 2001 to December 2002, 428 patients were under follow up with the department. In all, 40 renal transplant recipients reported with 44 episodes of pulmonary infection during this study period. All patients underwent detailed and appropriate investigations including specific laboratory tests, sputum analysis, X-ray chest, CT and BAL. The spectrum of the causative organisms and the utility of BAL as compared to the other methods of diagnosis were studied and compared.

Results: Out of the 44 episodes of pulmonary infection evaluated, single causative organism could be found in only 24 (54.5%) episodes and multiple etiologies were found in 15 (34.1%) episodes. No definitive cause could be found in 5 episodes. Out of 57 organisms isolated in the 44 episodes, 20 (45.4 %) were bacteria, 16 (36.3 %) each were M. tuberculosis and fungus, 3 were CMV infection and 2 were nocardia. BAL gave a diagnostic yield of 75.8% (25 out of 33 cases). Nine of forty patients died (mortality rate 22.5%) of which 6 deaths could be attributed directly to pulmonary infection. Out of these 9 patients who died, cause of pulmonary infection was bacterial in 5, fungal in 2 and CMV disease in 1. In one patient, organism could not be isolated.

Conclusions: Our study has shown that more than 1/3rd of pulmonary infections in renal transplant recipients can be attributed to multiple organisms. Bacterial infections were the commonest cause of post transplant pulmonary infection. Tuberculosis is common cause of pulmonary infection in these patients in our set up. Because of its high diagnostic yield, BAL should be considered in all patients with suspected pulmonary infections in the post transplant period.