Safe susceptibility testing of Mycobacterium tuberculosis by flow cytometry with the fluorescent nucleic acid stain SYTO 16

• Type: Article in International Scientific Journal
• Date: 2005

Authors

pina-vaz, c (Author) FMUP; costa-de-oliveira, s (Author) Other; rodrigues, ag (Author) FMUP

Journal

Title: Journal of Medical Microbiology

Vol. 54

Pages: 77-81

ISSN: 0022-2615

Publisher: Microbiology Society

Indexing

ISI Web of Knowledge - 35 Citations

Scopus - 39 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-000-63S

DOI: 10.1099/jmm.0.45627-0

Abstract (EN): The time needed to obtain susceptibility results of Mycobacterium tuberculosis using classsical methodologies is still too long, and flow cytometry is a promising technique in the setting of the clinical laboratory, giving fast results. A safe, reliable and rapid method to study susceptibility to streptomycin, isoniazide, rifampicin and ethambutol is described. Isolates of mycobacteria, grown for 72 h in the absence or presence of antimycobacterial drugs in the mycobacteria growth indicator tube (MGIT), were heat-killed, stained with SYTO 16 (a nucleic acid fluorescent, stain that only penetrates cells with severe lesion of the membrane) and then analysed by flow cytometry. Sixteen strains with different susceptibility patterns were tested and an excellent correlation with the BACTEC MGIT 960 protocol for susceptibility was shown. In contrast to resistant strains, sensitive strains lose their cellular integrity after incubation with antimycobacterial drugs, allowing SYTO 16 to penetrate the cells, Comparing the intensity of fluorescence of Mycobacterium, cells incubated with anti mycobacterial drugs with that of drug-free cells, after staining with SYTO 16, it was possible to distinguish between sensitive, intermediate and resistant phenotypes. Other cytometric assays have been described for mycobacteria susceptibility testing but these have lower accuracy and safety. The described flow cytometric assay is a simple, fast, safe and accurate way to determine susceptibility of M. tuberculosis.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 5