Disseminated Nocardia niwae Infection With Central Nervous System Involvement: A Report of Two Cases and Review of Literature

We describe two new cases of Nocardia niwae infection in a single center, together with two previously published cases identified through a literature review, to summarize the clinical, microbiological, and outcome patterns seen so far for this rare species.Of the four cases, three patients were immunocompromised, and one was immunocompetent.All four had disseminated infection with both central nervous system (CNS) and pulmonary involvement, and three were initially misdiagnosed as malignancy before Nocardia was identified.Two of the four patients died, and both were immunocompromised.Antimicrobial susceptibility was similar across the isolates tested: all four were susceptible to trimethoprim-sulfamethoxazole and linezolid, and all isolates with available data were susceptible to amikacin and resistant to amoxicillin-clavulanate. Across these four cases, N. niwae infection was consistently associated with dissemination and CNS involvement.Its tendency to mimic malignancy on imaging underscores the need for tissue biopsy with culture sensitivities and molecular diagnostic tests for timely diagnosis and targeted therapy.