Microbiology Quiz–Mycobacteria questions
1. The drug which acts at A in the above image is
(A) Bedaquiniline
(B) Delamanid
(C) PAS
(D) Pyrazinamide
Answer: Option (B) is the correct answer
Reference: Guidelines for use of delamanid in the treatment of drug resistant TB 2018; Pg 2
Option (B): Delamanid is a nitroimidazooxazole compound which inhibits mycolic acid synthesis
Option (A): Bedaquiniline is a diarylquinoline which inhibits ATP synthase
Option (C): PAS – inhibits synthesis of DNA precursor.
Option (D): Pyrazinamide – disrupts plasma membrane
2. A 49yr old aquarium worker presented to the OPD with multiple nodules and few non healing ulcers in right forearm. He gives a history of cleaning aquarium tanks regularly. Biopsy from the nodule showed acid fast bacilli. The probable etiological agent is
(A) Mycobacterium leprae
(B) Nocardia
(C) Mycobacterium marinum
(D) Mycobacterium avium intercellulare complex.
Answer: Option (C) is the correct answer
Reference: Apurba Sastry Essentials of Medical Microbiology 2nd edition pg no: 294
Option (C): The occupational exposure is suggestive of M.marinum which causes fish tank granuloma or swimming pool granuloma. It presents as tender nodules, papules and ulcers
Option (A): Mycobacterium leprae causes leprosy with hypopigmented anaesthetic patches in early lesions
Option (B): Nocardia causes Pulmonary nocardiosis, Disseminated nocardiosis and actinomycetoma.
Option (D): MAC complex is usually associated with pulmonary lesion and lymphadenitis.
3. Match the above
(A) a- ii, b-v, c-i, d-iii
(B) a-v, b-iv, c-iii, d-i
(C) a- ii, b- iv, c-i, d-v
(D) a- iii, b-v, c-ii, d-i
Answer: Option (C) is the correct answer
Reference: Apurba Sastry Essentials of Medical Microbiology 2ndedition pg no: 295
Option (C): As per Runyons classification a) M.marinum – photochromogens; b) M.gordonae – scotochromogens; c) M.abscessus – rapid grower; d) M.ulcerans – Non photochromogens
4. Which of the following statement is true regarding GeneXpert used in TB diagnosis
(A) Can detect rifampicin resistance only
(B) Can detect isoniazid resistance only
(C) Can detect both rifampicin and isoniazid resistance
(D) does not detect drug resistance
Answer: Option (A) is the correct answer
Reference: Apurba Sastry Essentials of Medical Microbiology 2nd edition pg no: 288
Option (A): GeneXpert simultaneously detects: (i) MTB complex DNA and (ii)
rifampicin resistance (mutations of the rpoBgene). It uses five probes targeting various sequences of rpoBgene
5. This instrument is based on
- RT PCR
- Automated liquid culture system
- CBNAAT
- Line probe assay
Answer: Option (2) is the correct answer
Reference: Apurba Sastry Essentials of Medical Microbiology 2nd edition pg no: 288
Option (2): This is BACTEC MGIT(Mycobacteria growth indicator tube) which is an automated liquid culture system to diagnose TB
Option (1): Nested PCR targeting IS6110 gene was the most common molecular test used earlier. Other gene targets in PCR are MPT64 gene, 65 KDa and 38 KDa genes.
Option (3): Cartridge based PCR used in TB diagnosis is CBNAAT – Genexpert.
Option (4): Line probe assay involves probe-based detection of amplified DNA in the specimen. The commercial kits available to perform LPA are GenoType and INNO-LiPA
David Angel Makel
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It is a long established fact that a reader will be distracted the readable content of a page when looking at its layout. The point of using that it has a more-or-less normal distribution of letters, as opposed to using
David Angel Makel
It is a long established fact that a reader will be distracted by the readable content of a page when looking at its layout. The point of using Lorem Ipsum that more-or-less normal distribution of letters, as opposed to using content here