Mycobacterial Diseases
Open Access

Improving Tuberculosis Detection with Fluorescein Diacetate Vital Staining

Rinaldo Grinberg^{* *}Correspondence: Rinaldo Grinberg, Department of Microbiology, Federal University of São Paulo, Brazil, Email:

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Description

Accurate and timely diagnosis, alongside effective treatment monitoring, is essential for controlling the spread of TB and ensuring successful patient outcomes. Traditional diagnostic methods, such as saliva smear microscopy and culture, have limitations in sensitivity and turnaround time. Fluorescein Diacetate (FDA) vital staining has emerged as a potential technique for detecting the viability of Acid-Fast Bacilli (AFB) in saliva samples, offering potential advantages in the diagnosis and management of pulmonary tuberculosis. FDA vital staining is a technique that distinguishes viable bacteria from non-viable ones based on the enzymatic activity of living cells. When FDA penetrates viable bacterial cells, it is hydrolyzed by intracellular esterases to produce fluorescein, a fluorescent compound that can be detected under a fluorescence microscope. Non-viable cells, lacking esterase activity, do not hydrolyze FDA and therefore do not fluoresce.

This property makes FDA vital staining particularly useful for identifying viable AFB in sputum samples from TB patients. The application of FDA vital staining in TB diagnostics offers several advantages over traditional methods. One of the primary benefits is its ability to rapidly and specifically identify viable mycobacteria. Conventional Ziehl-Neelsen staining and auramine-rhodamine staining detect both viable and non-viable AFB, which can complicate the assessment of treatment efficacy. In contrast, FDA vital staining provides a clearer picture of bacterial viability, which is crucial for monitoring the response to anti-TB therapy and determining the infectiousness of patients. Another significant advantage of FDA vital staining is its potential role in assessing treatment success and detecting drug resistance. By identifying viable AFB in sputum samples, clinicians can more accurately evaluate the effectiveness of anti- TB therapy and make informed decisions about treatment modifications.

Studies and efficacy

Studies have demonstrated the efficacy of FDA vital staining in detecting viable AFB in sputum samples. Research comparing FDA staining with traditional culture methods has shown a high correlation between the presence of fluorescing bacilli and the growth of mycobacteria in culture. This suggests that FDA staining is a reliable indicator of bacterial viability, offering a rapid alternative to culture, which can take several weeks to yield results. FDA vital staining can be particularly valuable in resource-limited settings where advanced diagnostic facilities are not readily available. The technique is relatively simple and costeffective, requiring only basic laboratory equipment and reagents. This makes it accessible for use in peripheral health centres and laboratories, enhancing the diagnostic capacity for TB in underserved regions.

Treatment success and drug resistance

FDA staining can help identify cases of Multidrug-Resistant TB (MDR-TB) by revealing persistent viable bacilli despite appropriate therapy, prompting further investigation and intervention. The technique requires fluorescence microscopy, which may not be available in all settings. Furthermore, while FDA staining provides valuable information about bacterial viability, it does not offer insights into the specific mechanisms of drug resistance or the precise bacterial load. Therefore, it is best used in conjunction with other diagnostic methods, such as molecular testing and culture, to provide a comprehensive assessment of TB infection.

Conclusion

Fluorescein diacetate vital staining is a valuable tool for detecting the viability of acid-fast bacilli in sputum samples from pulmonary tuberculosis patients. Its ability to rapidly identify viable mycobacteria offers significant advantages for diagnosing TB, monitoring treatment efficacy, and detecting drug resistance. While it may not replace traditional diagnostic methods, FDA vital staining can complement existing techniques and enhance the overall diagnostic capacity for TB, particularly in resource-limited settings. Further research and broader implementation of FDA vital staining could contribute to more effective TB control and improved patient outcomes worldwide.