Clinical patterns, species-specific correlations, and therapeutic outcomes of nocardiosis in immunocompetent individuals: a systematic analysis based on literature

BACKGROUND: Nocardiosis, traditionally an opportunistic infection, lacks comprehensive characterization in immunocompetent individuals. This study aimed to describe and analyze the demographics, clinical features, and outcomes of Nocardia infections in this population based on the literature. METHODS: A systematic analysis of 530 immunocompetent Nocardia cases (2020-2024) was conducted using reports from PubMed, CNKI, and MedNexus. Demographics, exposures, clinical characteristics, laboratory, treatment, and outcome were recorded and analyzed. RESULTS: Patients (median age: 59 years; 69.8% male) exhibited pulmonary (46.5%), cutaneous (20.0%), or cerebral (15.7%) involvements. Risk factors included soil/dust exposure (97/530, 18.3%), trauma (44/530, 8.3%), and comorbidities (255/530, 48.1%, e.g., diabetes, bronchiectasis). Cure/improvement (82.6%) group exhibited younger age (P = 0.01) and higher prevalence of local infections (P < 0.001), while more cases of disseminated infection (P < 0.001), N. farcinica (P = 0.01), and unclassified Nocardia spp. (P = 0.02) were in the deterioration/mortality group. Trimethoprim-sulfamethoxazole (71.9%) was the primary therapy. Species-specific patterns demonstrated: N. brasiliensis preferentially linked to cutaneous infections (P < 0.001), N. farcinica to cerebral disease (P < 0.001), and N. cyriacigeorgica to pulmonary involvement (P < 0.001). CONCLUSION: Nocardiosis in immunocompetent hosts demonstrates distinct risk profiles, site-specific species associations, and prognostic factors. Early diagnosis, species identification, and antimicrobial therapy are critical for optimizing outcomes. This study underscores the need for heightened clinical suspicion and improved diagnostic protocols in non-immunocompromised populations.