Nocardiosis in Japan: a multicentric retrospective cohort study

Abstract

Background Nocardia species cause a broad spectrum of infections, especially in immunocompromised patients. Given its relative rarity, data on the prognosis and distribution of nocardiosis from a large cohort are scarce. The present study aimed to scrutinize the clinical features and outcomes of nocardiosis in Japan, including one-year mortality and microbiological data. Methods The present, multicentric, retrospective cohort study enrolled patients aged ≥ 18 years with nocardiosis diagnosed between January 2010 and December 2017 and recorded their clinical and microbiological characteristics. Factors associated with one-year mortality were also determined using Cox proportional hazard analysis. Results In total, 317 patients were identified at 89 hospitals. Almost half (155/317, 48.9%) were receiving immunosuppressive agents, and 51 had disseminated nocardiosis (51/317, 16.1%). The one-year, all-cause mortality rate was 29.4% (80/272; lost to follow-up, n = 45). The most frequently isolated species was Nocardia farcinica (79/317, 24.9%) followed by the N. nova complex (61/317, 19.2%). Selected antimicrobial agents were generally effective, with linezolid (100% susceptibility [S]) and amikacin (94% S) having the most activity against Nocardia species. In Cox proportional hazard analysis, factors independently associated with one-year mortality were a Charlson Comorbidity Index score ≥ 5 (adjusted hazard ratio [aHR], 3.61; 95% confidence interval [CI], 1.95-6.71, P < 0.001) and disseminated nocardiosis (aHR, 1.79; 95%CI, 1.01-3.18, P = 0.047). Conclusions The presence of advanced comorbidities and disseminated infection, rather than variations in antimicrobial therapy or Nocardia species, were independently associated with one-year mortality.