Clinical features and outcomes of persons with cystic fibrosis and nocardia isolation: a systematic review

Background: Recurrent respiratory infections are a leading cause of morbidity and mortality in persons with Cystic Fibrosis (pwCF). Recently, the emergence of Nocardia species as a potential pathogen in CF has raised questions about its role and management, as its clinical significance and the optimal patient management remain unclear in current clinical practice. This review explores the clinical implications of Nocardia species in patients with Cystic Fibrosis (pwCF) through a comprehensive literature review. Key objectives include assessing its impact on lung function, identifying colonization risk factors, and evaluating an appropriate treatment. Methods: The literature review, conducted until June 30, 2023, from databases like MEDLINE, PubMed, Embase, and Cochrane, included 16 articles involving 89 pwCF with Nocardia species isolation according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guideline recommendations. Articles reporting Nocardia prevalence and symptoms based on original data in adult and paediatric pwCF were included. All the retrieved studies were observational ones, thus, they were categorized by study type as case report and case series. Results: Overall 89 pwCF and Nocardia species isolation were included: 42 children and 47 adults. Where reported, we found these main following bacterial species: Nocardia asteroides (35%, 23/64), Nocardia farcinica (21%, 14/64), Nocardia tranvalensis (13%, 8/64) and Nocardia cyriacigeorgica (11%, 7/64). A co-infection was reported in 85% of patients (61/72). Of patients whose lung function was reported before and after Nocardia isolation, 23% (16/68) showed a decline in FEV1. Above all, 82 patients were treated at least once after isolation of Nocardia strain. In 93% (77/82) of cases, treatment was started immediately upon isolation. Antibiotic treatment was performed per os or intravenously depending on the clinical condition of the individual patient. Nocardia eradication was attempted in only 32 cases out of 82, and 78% (25/32) of these patients were successfully eradicated after one or more courses of antibiotics. Death was reported in 3 patients, 2 of which were children. Conclusion: In general the isolation of the bacteria does not necessarily imply therapy, but patients need to be monitored closely to assess the possible occurrence of active infection. The treatment seems to be indicated in patients showing lung involvement with the possible appearance of pneumonia, pleural effusion, fever, cough, or a decrease in FEV1, as in the case that we described, or in patients undergoing pulmonary transplantation.