Mcb 5 Flashcards
(52 cards)
What is the purpose of In Situ Hybridization?
Uses an oligonucleotide probe labeled with a detector molecule to identify M. tuberculosis in cultures and direct respiratory specimens
If the detector molecule is fluorescein, it is referred to as Fluorescence In Situ Hybridization (FISH); if detection is by secondary reaction and color change, it is termed Chromogenic In Situ Hybridization (CISH)
What does the Enhanced Amplified-MTD test detect?
M. tuberculosis mRNA from both smear positive and smear negative specimens
The Ampiclor MTB test detects M. tuberculosis DNA from smear positive specimens only
When should Positive NAA and negative smear results be treated?
Initiate treatment based on clinical assessment while awaiting culture results
What does the Xpert MTB/RIF test identify?
M. tuberculosis and resistance to rifampicin
It purifies and concentrates MTB bacilli from sputum samples, isolates genomic material, amplifies genomic DNA by PCR, and identifies relevant mutations
What is a major disadvantage of the Xpert MTB/RIF test?
It is expensive
What are some examples of automated detection systems for TB?
- BACTEC 460TB
- BACTEC c-MGIT 960
- Versa TREK
- Myco BacT/Alert 3D
- ESP Culture System II
What is the gold standard for laboratory confirmation of TB?
Culture
What are the first-line drugs for TB treatment?
- Isoniazid
- Rifampicin
- Ethambutol
- Pyrazinamide
What is the definition of MDR-TB?
Resistance of M. tuberculosis strains to at least isoniazid and rifampicin
What is the main risk factor for progression from latent tuberculosis infection to active tuberculosis?
HIV infection
What is the definition of Pre-XDR-TB?
TB caused by M. tuberculosis strains that are resistant to isoniazid, rifampicin, and any fluoroquinolone (+ second line injectables)
What is the Zeihl-Neelsen staining technique used for?
To identify acid-fast bacilli in clinical specimens
What does the term ‘gas-liquid and HPLC’ refer to in TB investigations?
Methods used for the detection of Mycobacteria
What is the role of N-acetyl-L-cysteine in TB sample preparation?
Used in decontamination to remove fast-growing non-mycobacterial organisms
What does the term ‘Culture media’ include?
- Egg based (Lowenstein-Jensen, Petragnani)
- Agar based (Middlebrook 7H10 or 7H11)
- Liquid based (Middlebrook 7H9, 7H12, etc)
Fill in the blank: The TB-LAMP test refers to _______.
loop mediated isothermal amplification (TB Complex)
What is the purpose of DNA sequencing in TB diagnosis?
To provide information on the identity of the organism and susceptibility to Rifampicin
What is the definition of XDR-TB?
TB caused by M. tuberculosis strains that are resistant to isoniazid, rifampicin, any fluoroquinolone, and either bedaquiline or linezolid (or both)
What are the second-line drugs for MDR-TB management?
- Aminoglycosides (e.g., amikacin, kanamycin)
- Polypeptides (e.g., capreomycin, viomycin)
- Fluoroquinolones (e.g., Gatifloxacin, moxifloxacin)
- Thioamides (e.g., ethionamide, prothionamide)
- Cycloserine
- Terizidone
What is the significance of the insertion sequence IS6110?
It is specifically identified as the target of a DNA probe used in fingerprint analysis for epidemiological studies of tuberculosis
What is the main focus of primary TB infection in the lungs?
Subpleural and in the midlung zone
True or False: Lymphohematogenous dissemination can lead to the development of tuberculous meningitis.
True
What is the typical primary complex in TB infection?
Infected macrophages carried by lymphatics to regional lymph nodes, forming the Ghon complex
What percentage of infections is contained with no apparent disease?
95%
This refers to latent tuberculosis infection.
