Giacomelli LR, Sespede SR, Barreto AM, Cardoso CL; American Society for Microbiology. General Meeting.
Abstr Gen Meet Am Soc Microbiol. 1999 May 30-Jun 3; 99: 131 (abstract no. C-129).
State University of Maringa, Brazil.
Some authors have demonstrated that tubercle bacilli may survive in heat-fixed sputum smears, representing a risk factor for acquiring tuberculosis in the laboratory. However, it is unclear how long the tubercle bacilli can survive on heat-fixed slides prior to staining. In this study we used a slide culture technique to detect tubercle bacilli surviving on sputum smears immediately after air- drying and heat fixation (time 0), and after 24 h, 48 h, 72 h, and 7 days post-heat fixation. All sputum specimens (n=30) were obtained from patients in treatment for pulmonary tuberculosis and who were both smear- and culture- positive. Each smear was made by spreading sputum over a 25 x 10 mm area of a 76 x 13 mm glass slide, using a 10 microliter disposable loop. The smears were allowed to air within a safety cabinet. Next, duplicates of positive controls and tests were cultured by placing each slide in a 16 x 150 mm tube containing 8 mL of a selective lysed blood medium, and incubated at 37 degrees C for 7 days. The slides were then removed from the culture medium, rinsed briefly in distilled water, decontaminated with 5% sodium hypochlorite, stained by Ziehl-Neelsen stain, and examined with a compound microscope. The presence of cord-forming microcolonies was considered a positive test. In 15 of 30 sputum specimens, tubercle bacilli survived heat fixation after time 0 (n=2), 48 h (n=5), 72 h (n=3), and 7 days (n=5). Viable tubercle bacilli remaining in heat-fixed sputum smears may present an infection risk to laboratory staff.
Publication Types:
Keywords:
- Bacillus
- Coloring Agents
- Evaluation Studies
- Gram-Positive Bacteria
- Heat
- Humans
- Microscopy
- Mycobacteria, Atypical
- Mycobacterium bovis
- Mycobacterium tuberculosis
- Specimen Handling
- Sputum
- Staining and Labeling
- Tuberculosis
- Tuberculosis, Pulmonary
- methods
- organization & administration
Other ID:
UI: 102195564
From Meeting Abstracts