Sampling strategy for bacteriological diagnosis of intrathoracic tuberculosis

Area of Science:

• Microbiology
• Infectious Diseases
• Pulmonary Medicine

Background:

• Pulmonary tuberculosis (TB) is a leading cause of infectious disease spread globally.
• Current TB diagnosis often involves multiple, sometimes invasive, sample collections.
• Optimizing sampling strategies is crucial for efficient TB diagnosis.

Purpose of the Study:

• To review and analyze the effectiveness of different sampling strategies for microbiological diagnosis of pulmonary TB.
• To evaluate the yield of various sample types in confirming TB.
• To inform best practices for pulmonary TB diagnosis.

Main Methods:

• Retrospective analysis of 6267 samples from 2187 patients over a 20-month period (Sept 2014 - May 2016).
• Inclusion of all samples from patients over 18 years old undergoing bacteriological diagnosis for pulmonary TB.
• Data collected from the Bacteriology laboratory at Pitié-Salpêtrière Hospital, Paris.

Main Results:

• Pulmonary TB was confirmed in 6% of patients (126/2187).
• Sputum collections were sufficient for diagnosis in 63.5% of confirmed cases.
• Bronchoscopy was necessary in 29.4% of cases; gastric lavages were less effective in avoiding bronchoscopy (7.1%).
• Sputa showed higher culture positivity (8.6%) than bronchial aspirations (3.1%), BAL (2.3%), or gastric lavages (4.8%).
• Molecular testing on selected bronchial aspirations increased positive predictive value (PPV) from 70.0% to 88.9%.

Conclusions:

• Consistent sputum collection is recommended as the primary diagnostic approach.
• For smear-negative cases, bronchoscopy is advised.
• Molecular diagnosis should be strategically employed on specific bronchial aspirations, guided by bronchoscopist expertise.