Objective: Nocardiosis is an opportunistic infection that primarily targets the immunocompromised. We investigate the differences in demographics and characteristics between immunocompromised and immunocompetent patients with nocardiosis at a tertiary care hospital in Pakistan.

Methods and Materials: Retrospective records were reviewed for patients diagnosed with pulmonary nocardiosis between 2003 and 2020. Immunosuppressed individuals were identified as those with autoimmune and hematologic disease, malignancies, HIV, immunosuppressant therapy etc. Data collected included basic demographics, comorbid conditions, medication history, clinical presentation, radiological and microbiological data, and nocardiosis outcomes and complications.

Results: A total of 66 patients with nocardiosis were included in this study out of which 48 were immunosuppressed while 18 were immunocompetent. Both groups were compared for a number of variables including patient characteristics, underlying conditions, radiological findings, treatment regimen and outcomes. Past Pulmonary tuberculosis (TB) and weight loss were statistically significant characteristics (p<0.05) as 10% of Immunosuppressed (ISP) and 39% of immunocompetent (ICP) patients had history of past Pulmonary TB. Weight loss was the presentation in 12% ISP and 56% ICP patients.

Conclusion: Nocardiosis presents differently in immunosuppressed and immunocompetent patients. Nocardiosis should be considered in any patient presenting with treatment-resistantpulmonary or neurologicalsymptoms.