Radio mi metric BACTEC detect growth of M tuberculosis in how much time -
Ans. is 'b1 i.e., 2-3 weeks Laboratory diagnosis of T.B. T.B. Specimens Decontamination and concentration of specimens Smear Culture Nucleic acid amplification Immunodiagnosis o Sputum o Urine o Pleural fluid o CSF o Joint fluid o As sputum and other specimens frequently contain many bacteria & fungi that would rapidly overgrow mycobacteria on culture, they should be destroyed o Methods y Petroff's method (M.C.) y Flotation method y Autoclave method y Treatment with antiformin, Na2CO3 or hypochlorite y Detergents like tergitol o Ziehl-Neelsen staining o Fluorescence microscopy using auramine-rhodamine stain (more sensitive & rapid) Solid medium o L.J. medium (4-8 wk for growth) Liquid media o BACTEC-460 | Radiomimetic growth detection Within 2-3 wks. o PCR o Ligase chain reaction o R.N.A. specific PCR o Not very useful o Enzyme immune assay for detection of antibody to mycobacterial lipoarabinomannan o Definitive diagnosis depends on isolation and identification of M. tuberculosis from a diagnostic specimen. Remember y Sputum is best collected in the morning before any meal. y Sputum sampling on three days increases the chances of detection. y If sputum is not produced, bronchial washing, brushing or biopsies and early morning gastric aspirate may be examined. y At least 10000 (HP) bacilli should be present per ml of sputum for the demonstration in a direct smear. y Culture can detect 10-100 bacilli per ml. o For culture o For microscopy - - 10-100 bacilli per ml. > 10000 (104) bacilli perml.
1 week
2-3 week
4-8 week
> 10 weeks