How we treat Nocardia infections in transplant recipients and people with HIV

Background Nocardia spp. can cause a range of clinical syndromes in immunocompromised individuals, such as solid organ transplant recipients, haematopoietic stem cell transplant recipients, and people with HIV (PWH) with advanced HIV disease. Owing to its rarity as an opportunistic infection, its nonspecific clinical presentation, and the difficulties in establishing a definitive diagnosis, clinicians often face challenges in recognizing this infection. Furthermore, the limited literature and the lack of evidence-based guidelines leave clinicians without clear indications in the management of this condition. Objectives We aimed to provide guidance on the diagnosis and treatment of nocardiosis in transplant recipients and PWH. Sources We performed a review of case reports, case series, original articles, meta-analyses, and systematic reviews retrieved from PubMed. Content We reviewed and discussed the most challenging steps in the management of nocardiosis in solid organ transplant and haematopoietic stem cell transplant recipients and PWH through a clinical vignette including epidemiologic changes after the introduction of antiretroviral therapy for PWH; the clinical presentation and differential diagnosis; the role of immune reconstitution; diagnostic challenges and treatment options for an underresearched condition, and the possible role of primary prophylaxis for other opportunistic infections. Implications Nocardiosis is a rare but clinically significant opportunistic infection, especially in transplant recipients and PWH with advanced HIV disease. Diagnosis is challenging owing to its nonspecific clinical presentation and the difficulties associated with prolonged culture incubation. Therapeutic management is complex, owing to interspecies variability in antibiotic susceptibility, tolerability of first-line regimens and limited evidence available to guide treatment decisions.