Use of string test and stool specimens to diagnose pulmonary tuberculosis

Area of Science:

• Microbiology
• Infectious Diseases
• Diagnostic Medicine

Background:

• The Xpert MTB/RIF (MTB/RIF) test is a key tool for tuberculosis (TB) diagnostics.
• A significant challenge in diagnosing pulmonary TB (PTB) is the inability of 10-85% of patients to produce sputum, influenced by age and HIV status.

Purpose of the Study:

• To evaluate the feasibility of using the MTB/RIF assay and culture on alternative specimens.
• To assess the diagnostic utility of stool and string test specimens for PTB detection.

Main Methods:

• The study involved 13 adult patients with presumed PTB.
• Specimens were collected using a string test and stool samples.
• These specimens were analyzed using both MTB/RIF testing and microbiological culture.

Main Results:

• The string test was well-tolerated by patients.
• MTB/RIF testing of string test specimens demonstrated 100% sensitivity and specificity.
• Culture of string test specimens showed 87.5% sensitivity and 100% specificity.
• Mycobacterium tuberculosis DNA was detected in all culture-confirmed PTB cases using stool specimens.

Conclusions:

• The string test and stool specimens are viable alternatives for PTB diagnosis.
• These alternative specimens demonstrate high diagnostic accuracy, particularly with MTB/RIF.
• Further research is warranted to establish these methods in clinical practice.