Advances and Challenges in Laboratory Diagnosis of Nocardia Infections: Traditional and Emerging Approaches

Nocardia spp. are filamentous bacteria that may cause nocardiosis; however, the disease’s clinical symptoms often mimic tuberculosis, fungal infections and malignancies, complicating diagnosis. Several factors limit the effectiveness of traditional cultures and biochemical methods, including slow bacterial growth, challenges in interpreting the variable partial acid-fast stain, and suboptimal sensitivity and specificity. Molecular techniques such as real-time polymerase chain reaction (real-time PCR), multilocus sequence analysis (MLSA) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) enhance species identification but are costly, technically complex, and, in the case of real time PCR, prone to false positives due to airway colonization. Matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) accelerates identification, but its accuracy depends on robust reference spectra and optimized extraction protocols, particularly for gram positive actinomycetes. Advanced genomic tools, including whole genome sequencing (WGS) and metagenomic next generation sequencing (mNGS), offer high resolution strain differentiation and antimicrobial resistance profiling; however, their widespread clinical use is limited by high costs and complex data interpretation. To address these limitations, emerging technologies such as Raman spectroscopy and electrochemical sensors promise rapid and sensitive detection but are still largely experimental. Current challenges include a lack of standardized protocols, limited accessibility in resource-poor settings, and gaps in standardized antimicrobial susceptibility testing. Integrating genomic and proteomic approaches may improve diagnostic accuracy and support targeted therapeutic strategies. Despite technological advances, development of rapid, affordable diagnostic tools is essential to improve detection of nocardiosis. In this review, advances and challenges in laboratory diagnosis of Nocardia infections are discussed.

کلیدواژه ها:

Nocardia spp. ، Nocardiosis ، Molecular techniques ، Emerging technologies