Clinical and microbiological characteristics of Nocardia infections: a 10-Year multicentre study from Türkiye

Multicentre studies from countries such as Spain, Australia, Japan, China, and Taiwan have revealed significant geographic variation in Nocardia species patterns, resistance profiles, and patient outcomes. In Türkiye, however, most available data originate from single-centre reports with limited species-level identification and antimicrobial resistance profiling, highlighting a significant gap in the current understanding of nocardiosis at the national level. Our aim was to evaluate the clinical and microbiological characteristics of Nocardia infections in Türkiye. In this multicentre, retrospective observational cohort study, adult patients (≥ 18 years) diagnosed with microbiologically confirmed nocardiosis between January 1, 2014, and December 31, 2024 from 18 tertiary care hospitals in Türkiye were examined. 109 microbiologically confirmed nocardiosis cases were identified, with a mean age of 55.9 years (median 59, range 18–80) and a predominance of male patients (66.1%). The most common presenting symptom was productive cough (40.3%), and sputum was the most frequent specimen type yielding Nocardia isolates (41.2%). Species-level identification was achieved in 51 cases, with Nocardia farcinica (41.2%), N. cyriacigeorgica (29.4%) being the most prevalent species. In multivariate logistic regression, increasing age was independently associated with mortality (OR = 1.053, 95% CI 1.012–1.096, p = 0.011) and the CCI was independently associated with mortality (OR = 1.244, 95% CI 1.043–1.483, p = 0.015). This study demonstrates that clinical outcomes in nocardiosis are primarily dictated by patient-intrinsic factors, namely advanced age and cumulative comorbidity burden. This finding requires confirmation in prospective studies.