Epidemiology and Drug Resistance of Pulmonary Nocardiosis Among Tuberculosis-Suspected Patients in Guangzhou, China.

OBJECTIVE: This study aimed to analyze the detection characteristics, species distribution, and drug susceptibility profiles ofisolates among tuberculosis-suspected patients in the Guangzhou region, thereby offering valuable insights for clinical diagnosis and treatment.

METHODS: This study included 77,550 clinical samples collected from tuberculosis-suspected patients. All specimens were cultured using the MGIT 960 liquid culture system. Culture-positive isolates underwent acid-fast staining, followed bysubculture purification and species identification using mass spectrometry. Subsequently, antimicrobial susceptibility testing was performed on 97clinical isolates against 13 antimicrobial agents.

RESULTS: Species identification revealedas the predominant species, accounting for 95.36% of all isolates. Morphological analysis following cultivation showed thatexhibited partial acid-fast staining characteristics, with a light blue background and faint red or pink filamentous bacilli displaying definitive branching structures. These features clearly distinguished it from the cord-like arrangements typically observed in mycobacteria. Antimicrobial susceptibility testing demonstrated that co-trimoxazole, amikacin, moxifloxacin, and linezolid were reliable therapeutic options. In contrast, the tested β-lactams, macrolides, and tetracyclines exhibited high resistance rates, limiting their clinical utility.

CONCLUSION: This study elucidates the epidemiological characteristics and antimicrobial susceptibility profiles ofinfections in Guangzhou, providing valuable insights for early diagnosis and targeted therapy. Morphological analysis serves as an effective tool for reducing the risk of misdiagnosingas mycobacteria. Future efforts should focus on optimizing detection methods and conducting multicenter studies to better understand prevalence trends and resistance mechanisms, ultimately improving clinical management.