Think TB! Is the diagnosis of pulmonary tuberculosis delayed by the use of antibiotics?

SETTING: Effective tuberculosis (TB) control requires prompt diagnosis of infectious cases through early suspicion of pulmonary TB in all subjects with suspected respiratory infection.

OBJECTIVE: To test our hypothesis that prior antibiotic treatment for presumed bacterial infection leads to a delay in diagnosing TB in a European country with low TB incidence.

DESIGN: Adults with culture-confirmed pulmonary TB at a single metropolitan centre were assessed for the impact of any previous antibiotic treatment on symptoms and the time to starting specific anti-tuberculosis treatment.

RESULTS: Of 83 patients, 42 (51%) received antibiotics prior to TB diagnosis, with symptomatic improvement reported in 20 of the 42 (48%) patients. This was unrelated to specific drug class. Although the median time to diagnosis in subjects receiving antibiotics was prolonged (P = 0.001), this was not predicted by treatment response. In 94% of cases, the initial chest radiograph was suggestive of TB infection.

CONCLUSION: Patients receiving antibiotics prior to TB confirmation experience a process-related delay in starting treatment. To minimise the risk of ongoing TB transmission, we propose that clinicians should include TB in their differential diagnosis and initiate simple, TB-focused investigations early on in the diagnostic process.