Objective: We evaluated a simplified method for processing three serial sputum samples as a single sample, and compare the results with those obtained when processing three samples individually.
Material and methods: During a 32-week period, we studied 867 sputum samples from 289 patients with pulmonary tuberculosis suspicious. Samples from 148 patients (n = 444) were processed by simplified method, and samples from 141 patients (n = 423) were processed by individually method. All cultures were processed by ESP Culture System II (Difco Laboratories, USA).
Results: Seven mycobacterium's strains were isolated by individually method. Simplified method detected another seven strains. In both cases, four strains were identified as Mycobacterium tuberculosis. Mean time to detection mycobacteria were 21.5 and 24 days for simplified and individually method, respectively. Cultures from 21 patients were contaminated (11 patients by simplified method and 10 patients by individually method). Mean time to detection contaminated cultures were 8 days and 7.5 days for simplified and individually method, respectively.
Conclusion: Simplified method may be a useful alternative in laboratories that must handle increasing numbers of samples, without decline in diagnostic performance.