TB patients: Is sputum disinfection important?

Background: Patients with pulmonary tuberculosis (TB) may produce large amount of infectious sputum which needs to be handled carefully both in health care and household settings. As mycobacteria may survive for long duration in sputum; proper collection, disinfection and disposal is necessary to avoid potential disease transmission. We aimed to assess the efficacy of bedside disinfectant treatment of sputum produced by TB patients using easily available disinfectants that can be used both in TB wards and household settings, to sterilize the infected sputum and compared it with sputum without disinfectant treatment.

Methods: It was a prospective case control study. Sputum of total 95 patients with sputum smear positive pulmonary tuberculosis was collected in sputum containers with lids. Patients on anti-tubercular treatment for more than 2 weeks were excluded. Each patient was given 3 sterile sputum containers to expectorate, Container A containing 5% Phenol solution, Container B containing 4.8% Chloroxylenol and Container C without any disinfectant, acting as a control. Thick sputum was liquified with Mucolytic agent N-acetyl cysteine (NAC). Aliquots of the sputum were sent for culture in Lowenstein-Jensen medium on day 0 (to confirm alive mycobacteria) and on day 1 i.e., after 24 hours (to evaluate effective sterilization). Drug resistance testing was done on all grown mycobacteria.

Results: If the samples on day 0 did not grow mycobacteria (indicating non-viable mycobacteria) or day 1 sample grew contaminants in any of the three containers, they were excluded from the analysis (15/95). In remaining 80 patients, bacilli were alive on day 0 and remained alive even after 24 hours (day 1) in control samples (without disinfectants). The sputum was effectively disinfected resulting in no growth after 24 hours (day 1) in 71/80 (88.75%) containing 5% Phenol and 72/80 (90%) with 4.8% Chloroxylenol. The efficacy of disinfection was 71/73 (97.2%) and 72/73 (98.6%) for drug sensitive mycobacteria respectively. The mycobacteria however remained alive with these disinfectants in all 7 samples of drug-resistant mycobacteria with an efficacy of 0%.

Conclusion: We recommend use of simple disinfectants like 5% Phenol or 4.8% Chloroxylenol for safe disposal of sputum of pulmonary tuberculosis patients. It is necessary as sputum collected without disinfection remained infectious after 24 hours. Resistance of all drug resistant mycobacteria to disinfectants was a novel chance finding. This needs further confirmatory studies.