Survival of tubercle bacilli in heat-fixed and stained sputum smears

• Main Authors: Celso Luíz Cardoso, Luiz Roberto Bigão Giacomelli, César Helbel, Janete Jordão Sant'Ana, Fátima Moreira Martins, Angela Maria Werneck Barreto
• Format: Article
• Language: English
• Published: Instituto Oswaldo Cruz, Ministério da Saúde 2001-02-01
• Series: Memórias do Instituto Oswaldo Cruz.
• Subjects: tubercle bacilli; slide culture; sputum smear
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0074-02762001000200024

We used a slide culture technique to detect tubercle bacilli surviving in sputum smears (n=46) after conventional heat fixation and Ziehl-Neelsen staining. In all heat-fixed sputum smears, tubercle bacilli survived after time 0 (n=22), 24 h (n=7), 48 h (n=7), 72 h (n=4), and seven days (n=6). None of the stained sputum smears showed growth on slide cultures. Viable tubercle bacilli remaining in heat-fixed sputum smears for at least seven days may present an infection risk to laboratory staff. Thus, sputum smears should be stained immediately by the Ziehl-Neelsen method or stored in a safe container to avoid transmission of tuberculosis.