Liquid mycobacterial culture outcomes after different sputum collection techniques before and during treatment

Mycobacterial sputum culture is a key diagnostic and research tool. To compare mycobacterial culture outcomes of three sputum collection methods. We compared culture results within sets of three sputum samples collected from 18 HIV-infected adult tuberculosis patients at regular intervals up to 84 days after treatment initiation. The first sputum was collected at home and brought to the clinic, where a second and third sputum were consecutively collected under supervision following mouthwash with bottled water and chlorhexidine solution respectively. All sputa were processed for liquid culture in duplicate. Out of 556 cultures 430 (77.3%), 91 (16.4%) and 35 (6.3%) were positive, negative or contaminated, respectively. The odds of contamination were higher with home collection and with water rinse than with chlorhexidine rinse (OR: 12.5, p