Nocardia Diagnosis In Lab: Correcting The Oversight

Nocardiosis is a rare bacterial illness that can cause a wide range of symptoms in both immunocompetent and immunocompromised individuals. Although nocardiosis is often misdiagnosed due to its low occurrence and unusual symptoms, it is crucial to recognise this infection in order to select the best antibiotic treatment.

Over time, the laboratory diagnosis of Nocardia has changed significantly, moving from traditional microscopy to advanced molecular techniques. Gram stain was used for direct microscopic examination of clinical specimens and weak decolourizers for modified acid-fast staining, to highlight partially acid-fast organisms. Culture on routine media, although slow with extended incubation, has long been considered the diagnostic gold standard, followed by phenotypic and biochemical tests for species identification.

Technological developments have greatly increased the precision and speed of species-level identification through the use of molecular techniques like 16S rRNA gene sequencing and polymerase chain reaction (PCR). More recently, a move toward quicker, more accurate diagnostic methods has been signalled by the rapid and dependable identification of Nocardia species in clinical laboratories using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).

Despite advancements in diagnostics, the nature of nocardiosis makes clinical, radiographic, and histological diagnosis challenging. From specimen handling to reporting, there are usually multiple processing checkpoints where missed diagnoses can happen. Therefore, close cooperation between clinical microbiologists and clinicians is necessary for the diagnosis of nocardiosis.

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