Clinical characteristics, susceptibility profiles, and treatment of nocardiosis: a multicenter retrospective study in 2015-2021

Objectives: This study aimed to investigate the microbiological characteristics, antimicrobial resistance profiles, antibiotic choice, and outcomes of Nocardia infection in various centers over a 7-year period (from 2015 to 2021). Methods: We retrospectively analyzed the medical records of all hospitalized patients diagnosed with Nocardia between 2015 and 2021. The isolates were identified to the species level through the sequencing of 16S ribosomal RNA or secA1 or ropB genes. The susceptibility profiles were determined using the broth microdilution method. Results: Of the 130 nocardiosis cases, 99 (76.2%) were established as pulmonary infection, of which the most common underlying disease was chronic lung disease (40.4%, 40/99), including bronchiectasis, chronic obstructive pulmonary disease, and chronic bronchitis. Among 130 isolates, 12 species were identified, with the most common species being Nocardia cyriacigeorgica (37.7%) and Nocardia farcinica (20.8%). All Nocardia strains were susceptible to linezolid and amikacin, and the susceptibility rate of trimethoprim-sulfamethoxazole (TMP-SMX) was 97.7%. Of the 130 patients, 86 (66.2%) received TMP-SMX monotherapy or multidrug regimen. Furthermore, 92.3% patients who were treated achieved clinical improvement. Conclusion: TMP-SMX was the treatment of choice for nocardiosis, and other combination drugs with TMP-SMX therapy yielded even better results.