Mycobacteria Multiple Choice Question And Answers

Question 1. BCG is maximally protective against:

1. Pulmonary TB
2. Pulmonary and CNS TB
3. CNS and Disseminated TB
4. Extrapulmonary

Answer. (3) (CNS and Disseminated TB)

Though BCG may not protect from the risk of tuberculosis infection, it surely gives protection to infants and young children against development of complications such as tuberculous meningitis and disseminated tuberculosis……………

Read And Learn More: Micro Biology And Immunology Multiple Choice Question And Answers

Question 2. Drugs used in XDR-TB:

1. Amikacin
2. Fluoroquinolone
3. Pyrazinamide
4. Streptomycin
5. Ethionamide

Answer. (1, 2) (Amikacin, Fluoroquinolone)

Drugs used in XDR-TB is based on the drug susceptibility test.

• Aminoglycoside: kanamycin, amikacin or capreomycin
• Fluroquinolone: Ofloxacin or levofloxacin
• Ethionamide, Cycloserine

Question 3. True about bedaquilline is:

1. New antibacterial class
2. MOA is ATP synthase inhibitor
3. Given for 12 month schedule
4. Highly efficient as solo-drug regime
5. Used for XDR-TB

Answer. (1, 2, 5) (New antibacterial.., MOA is ATP.., Used for XDR-TB)

Bedaquiline is a new second-line ATD of the Diarylquinoline class, approved for use as second-line ATD since 2015. It is considered as miracle drug for the treatment of XDR-TB.

• It acts by inhibiting mycobacterial ATP synthase
• Regimen: Bedaquiline-containing regimen should contain four other second-line ATDs depending up on the sensitivity.

Question 4. New RNTCP software available online for TB monitoring is

1. Nikshay
2. Nirbhaya
3. e-DOT
4. Nischay

Answer. (1) (Nikshay)

• Nikshay is a web-based solution for monitoring of TB patients. All new cases should be reported into this web portal.

Question 5. Under RNTCP, how many sputum samples are taken from a suspected case of TB (DNB 2018 Pattern)

1. 1
2. 2
3. 3
4. 4

Answer. (2) (2)

Question 6. When do you say a patient is an MDR suspect?

1. Patient is on ATT and positive smear after 5 months
2. Patient is on ATT and positive smear after 2 months
3. Patient is on ATT and positive smear after 4 months
4. Previously smear negative becoming positive after 4 months of ATT

Answer. (3) (Patient is on ATT and positive smear after 4 months)

Question 7. The picture below depicts a bacterium which is most consistent with:

1. Streptococcus pyogenes
2. Nocardia asteroides
3. Mycobacterium tuberculosis
4. Corynebacterium diphtheriae

Answer. (3) (Mycobacterium tuberculosis)

This is an acid-fast stained smear showing long slender beaded red color acid-fast bacilli,blue color-stained pus cells and epithelial cells with background stained blue.

Question 8. Detection of lipoarabinomannan (LAM) antigen in urine has been used to screen patients for infection with which of the following:

1. Pneumocystis jirovecii
2. Cryptococcus neoformans
3. Toxoplasma gondii
4. Mycobacterium tuberculosis

Answer. (4) (MTB)

• Lipoarabinomannan (LAM) is the main component of M. tuberculosis cell wall. LAM detection in urine by rapid test such as ICT is a non-invasive alternative for diagnosing TB.

Question 9. Which of the following laboratory tests for Mycobacterium tuberculosis requires ONLY whole blood as a sample?

1. Fluorescent staining
2. GeneXpert MTB
3. Interferon Gamma release assay
4. ZN staining

Answer. (3) (Interferon Gamma release assay)

• Interferon Gamma release assay is performed on the whole blood.
• Whole blood is not recommended for geneExpert, neither for staining methods for tuberculosis.

Question 10. Two sputum samples of TB suspect given one at spot and other in morning are labelled as:

1. A B
2. 1 2
3. Alpha-beta
4. Y Z

Answer. (1) (A B)

• The two sputum specimens (early morning and spot) are labelled as A and B

Question 11. Pleural fluid from a suspected patient of TB is sent to laThis cannot be used for measuring which of the following parameter?

1. Gene Xpert
2. LDH
3. Albumin
4. ADA

Answer. (1) (Gene Xpert)

For Gene Xpert; pleural biopsy is the preferred specimen. Pleural fluid is suboptimal specimen.

Question 12. Which of the following stains is/are used for detection of M. tuberculosis?

1. Auramine
2. ZN
3. Gram stain
4. Giemsa stain
5. Albert’s stain

Answer. (1, 2) (Auramine, ZN)

• Auramine and ZN stains are used for detection of M. tuberculosis.
• Though M. tuberculosis is gram-positive, it is not usually done for diagnosis.

Question 13. Agent used in interferon-gamma release assay for diagnosing latent tuberculosis is:

1. MPT 64
2. Mycolic acid
3. Lipoarabinomannan
4. ESAT-6

Answer. (4) (ESAT-6)

• Interferon Gamma Release Assay (IGRA) uses highly specific M. tuberculosis antigens such as CFP10 (culture filtrate protein) and ESAT6 (early secreted antigenic target-6).

Question 14. Xpert MTB/RIF test is/are used for:

1. For assessing resistance to isoniazid
2. For assessing multi-drug-resistant TB
3. For assessing rifampicin resistance
4. Monitoring drug response in MDR TB
5. Diagnosis of TB

Answer. (3, 5) (For assessing rifampicin resistance, Diagnosis of TB)

The Xpert MTB/RIF is a cartridge-based, fully automated diagnostic test that can:

• Identify Mycobacterium tuberculosis DNA and resistance to rifampicin (RIF) simultaneously
• It works on the principle of PCR i. Only detects the DNA but cannot quantify the DNA, hence NOT suitable for monitoring disease progression. Real-time PCR is the best for this purpose.
• Provides accurate results in less than two hours so that early treatment can be started
  Has minimal bio-safety requirements, training, and can be done in any laboratories.

Question 15. Mycobacteria can be stained by:

1. Ziehl Neelsen stain
2. Kinyoun stain
3. Auramine rhodamine
4. GMS (gomori methanamine stain)
5. Albert stain

Answer. (1, 2, 3) (Ziehl Neelsen stain, Kinyoun stain, Auramine rhodamine)

Mycobacterium tuberculosis being acid fast can be stained by acid fast staining:

• Ziehl-Neelsen staining (hot method) or its modifications such as:
  • Kinyoun’s stain (cold acid fast staining) or
  • Gabbett’s staining method
• Fluorescent staining such as Auramine rhodamine staining method.

Question 16. XDRTB is defined as:

1. Resistant to Amikacin + Ofloxacin
2. Resistant to INH + Rifampicin
3. Resistant to INH + Rifampicin + Amikacin
4. Resistant to Rifampicin + Amikacin + Ofloxacin
5. Resistant to INH + Rifampicin + Amikacin + Ofloxacin

Answer. (5) (Resistant to INH + Rifampicin)

XDRTB is defined as at least MDR TB ( i.rifampicin + isoniazid) + Resistant to one fluoroquinolone (ofloxacin) + one injectable second-line aminoglycosides (Amikacin or kanamycin or capreomycin).

Question 17. Which is used in digestion and decontamination of sputum in smear preparation?

1. NaOH
2. KOH
3. NaCl
4. KCl
5. N-acetyl-L-cysteine

Answer. (1, 5) (NaOH, N-acetyl-L-cysteine)

Sputum and specimens from non-sterile sites need prior treatment for digestion (to liquefy the thick pus cells and homogenization) and decontamination (to inhibit the normal flora) and concentration (to increase the yield).

• Petroff’s method (4% NaOH): Most commonly followed
• NALC (N-acetyl-cysteine) + 2% NaOH: This is superior to Petroff’s method for isolation. NALC liquefies the sputum and NaOH kills the normal florThis method is better compatible with automated culture systems.
• If for only smear microscopy, then formalin or hypochlorite can also be used as mucolytic and for killing the bacilli. However, they are not useful for culture or animal pathogenicity.

Question 18. Multidrug therapy is given for tuberculosis because:

1. To delay development of resistance
2. To reduce toxicity
3. To broaden antimicrobial spectrum
4. To prevent toxin release from the organism

Answer. (1) (To delay development of resistance)

• Resistance to anti-tubercular drug is mainly due to mutational drug resistance which can be overcome by combination of drugs.

Question 19. Which of the following statements is true about BCG vaccination?

1. Distilled water or normal saline is used as diluents for BCG vaccine
2. The site for injection should be cleaned thoroughly with spirit
3. Tuberculin test is positive after 6 weeks of vaccination
4. WHO recommends Danish 1331 strain for vaccine production

Answer. (4) (WHO recommends Danish 1331 strain for vaccine production)

• WHO recommends Danish 1331 strain for vaccine production (M.bovis). In India, it is prepared in Guindy, Chennai
• Normal saline is recommended as diluents for BCG vaccine as distilled water is irritant
• The site for injection should be cleaned thoroughly with soap but disinfectant or antiseptic should not be useIf alcohol is used then it should be evaporated before the vaccination is given
• Tuberculin test is positive after 8 weeks of BCG vaccination but in some it might require 14 weeks.

Question 20. Acid fast organism(s) is/are:

1. Atypical mycobacteria
2. Rickttesia
3. Nocardia
4. Chlamydia

Answer. (1, 3) (Atypical mycobacteria, Nocardia)

Question 21. Method of testing resistance to drugs in TB are all expect:

1. Radiometric broth method
2. Molecular method
3. Disk diffusion method
4. PCR

Answer. (3) (Disk diffusion method)

• Disk diffusion method is used for drug susceptibility testing for most of the bacteria; however, it is not used for M.tuberculosis.
• Various methods used for drug susceptibility testing for M.tuberculosis:

Question 22. The best diagnostic procedure of M. tuberculosis:

1. PCR
2. Auramin rhodamine stain
3. Sputum culture
4. ESR

Answer. (3) (Sputum culture)

• Culture is the gold standard for diagnosis of tuberculosis with detection thresh hold of 10–100 bacilli/ml.
• Also, it detects the viability of the organism.
• It is more sensitive than acid fast smear and approaches 100% specificity.

About Other Options:

• PCR though can detect even 1 bacilli/ml, but it is not the gold standard because:
  • False –ve PCR might occur by presence of PCR inhibitors in sample or
  • False +ve PCR might occur due to contamination during the procedure
  • More so it can not detect the viability of the organism.
• However PCR is useful in:
  • Extrapulmonary tuberculosis (where Culture is less sensitive)
  • For rapid diagnosis along with rapid drug sensitivity detection.
• Staining (ZN and Auramin rhodamine stain) though it is rapid, but sensitivity is low (detection limit of 104 bacilli/ml.
• ESR is nonspecific, can be elevated in no. of condition.

Question 23. Collection of urine sample of a patient of TB/kidney:

1. 24 hrs urine
2. 12 hrs urine
3. In early morning
4. Any time

Answer. (3) (In early morning)

‘The 1st urine passed on the day i.Early morning sample is recommended for tuberculosis of urinary tract.’

• Most commonly collected Sample for UTI: Midstream urine
• Best Sample for UTI: suprapubic aspiration
• Sample for UTI for infant: suprapubic aspiration
• Best Sample when urethritis or prostatitis is suspected: Initial flow of urine
• If delay is expected to process, then: Store by refrigeration at 4°c or add boric acid 1.8%.

Question 24. Tuberculin test is done for:

1. Previous or present sensitization to tuberculous protein
2. Patient is resistant to TB
3. Patient is susceptible to TB
4. Individual is suffering from TB

Answer. (1) (Previous or present sensitization to tuberculous protein)

• Positive tuberculin test indicates:
• Active infection in infants (suffering from TB)
• Prevalence of infection
• Past exposure to TB bacilli in adult (Previous or present sensitization to tuberculous protein)
• Option b and c: ‘Tuberculin test does not indicate susceptibility or resistance to TB whereas Lepromin test is used to assess individual resistance to Leprosy’.

Question 25. The tuberculosis bacilli was discovered by: (TN 2005)

1. Robert Koch
2. Edward Jenner
3. Louis Pasteur
4. Jonas Salk

Answer. (1) (Robert Koch)

‘Robert Koch in 1882 isolated mammalian tubercle bacillus and proved its causative role in tuberculosis by satisfying Koch’s postulate where as: Lepra bacillus was 1st described by Hansen.’

Question 26. Outbreak of abscess following vaccine injection can be caused by which mycobacteria

1. M fortuitum
2. M. scrofulaceus
3. M hordinae
4. M avium

Answer. (1) (M. fortuitum)

• M. fortuitum and M. chelonae: They cause post-trauma injection abscess and catheterrelated infections

Question 27. Pigment-producing atypical mycobacteria:

1. M. fortuitum and M. chelonae
2. M. gordonae and M. szulgai
3. M. xenopi and MAC
4. M. ulcerans

Answer. (2) (M. gordonae and M. szulgai)

Pigment-producing atypical mycobacteria:

• Photochromogen: M marinum, M simiae, M. asciaticum, M kansasii,
• Scotochromogen: M. scrofulaceum, M szulgai, S.gordonae.

Question 28. Fish tank granuloma is caused by:

1. M. kansasi
2. M.marinum
3. M.paratuberculosis
4. M.gordonae
5. M.scrofulaceum

Answer. (2) (M. marinum)

• M. marinum (e.g. of Photochromogen) is originally isolated from fish is the causative agent of swimming pool or fish tank granuloma.
• This condition is associated with development of superficial granulomatous lesions in the skin.

Question 29. Rapidly growing Atypical organism involved in lung infection:

1. M. chelonae
2. M. fortuitum
3. M. abscessus
4. M. kansasi

Answer. (3) (M. abscessus)

• Any of the rapidly growing Mycobacteria such as M chelonae, M fortuitum and M. abscesses can cause pulmonary infection but infection with M. Abscessus may be particularly dangerous
• M. kansasii ……. Belongs to photochromogen:
  • Can cause a clinical syndrome that strongly resembles tuberculosis, consisting of hemoptysis, chest pain, and cavitary lung disease.
• MAC: Most Common Causes of pulmonary nontuberculous mycobacterial infection.
• The rapidly growing NTM, M chelonae, M fortuitum and M. abscessus, acquired via skin contamination from surgical instruments (especially in cosmetic surgery), injections,and other procedures. These infections are typically accompanied by painful,erythematous, draining subcutaneous nodules, usually without associated fever or systemic symptoms.

Question 30. Which is not a mycobacteria tuberculosis complex organism?

1. M. africanum
2. M. tuberculosis
3. M. bovis
4. M. kansasii

Answer. (4) (M. kansasii)

• M. tuberculosis complex include following species:
• M. tuberculosis
• M. bovis (bovine tubercle bacillus)
• M. africanum
• M. microti (vole tubercle bacillus)

Question 31. Which one of the following statement is true regarding pathogenicity of Mycobacteria species?

1. M. tuberculosis is more pathogenic than M. bovis to the humans
2. M. kansasii can cause a disease indistinguishable from tuberculosis
3. M. africanum infection is acquired from the environmental source
4. M. marinum is responsible for tubercular lymphadenopathy

Answer. (2) (M. kansasii can cause a disease indistinguishable from tuberculosis )

• “Mycobacterium kansasii produce human disease indistinguishable from tuberculosis”
• M. kansasii i is the most pathogenic non-tuberculous mycobacterial species affecting the lung, and the clinical features of M. kansasii disease resemble those of tuberculosis.
•  NTM causing human infection
  About Other Options:
• Option a: M. tuberculosis and M.bovis are equally pathogenic to humans and guinea pig.
• Option c: M. africanum belongs to the members of Mycobacterium tuberculosis complex. It is commonly found in West African countries, causing up to a quarter of cases of tuberculosis in countries such as the Gambi‘It is an infection of humans only and is spread by an airborne route from individuals with open cases of disease.’ Source- Wikipedia
• Option d: ‘M. marinum causes swimming pool granuloma/fish trank granuloma/fish fancier’s finger. Secondary lesions appear along with dermal lymphatics.’ (Sporotrichoid spread)

Question 32. Which of the following is known as Battey bacillus?

1. Mycobacterium intracellulare
2. Mycobacterium tuberculosis
3. Mycobacterium leprae
4. Mycobacterium kansaai
5. M. LEPRAE

Answer. (1) (Mycobacterium intracellulare)

Question 33. Seen in Leprosy is/are:

1. Saddle nose
2. Small ear lobe
3. Ptosis
4. Leonine facies
5. Lagophthalmos

Answer. (1, 4, 5) (Saddle nose, Leonine facies, Lagophthalmos)

• In leprosy, earlobes are enlargeOculomotor nerve doesn’t get involved, so ptosis is also not a feature.

Question 34. False about leprosy:

1. Multi bacillary leprosy: > 5 lesions
2. New case detection rate: Indicator of incidence
3. Target elimination of leprosy: Prevalence < 1/10,000 population
4. Defaulter: Not taken treatment for >6 months

Answer. (4) (Defaulter: Not taken treatment for > 6 months)

• Multibacillary leprosy: Bacteriological index ≥ 2, skin lesion: > 5, nerve involvement: ≥ 1
• New case detection rate: Indicator of incidence
• Target for elimination of leprosy: Prevalence < 1/10,000 population
• Defaulter: Not taken treatment for ≥ 2 months.

Question 35. ENL occurs in:

1. Due to lepromin test
2. Due to multi drug therapy
3. In LL patients
4. In TT patients

Answer. (3) (In LL patients)

• ENL occurs in type II lepra reaction in LL and BL patients.

Question 36. False about lepromin test:

1. Negative in children < 6 month age
2. It is a diagnostic test
3. Used to classify leprosy
4. BCG vaccine may convert a negative lepromin test to positive

Answer. (2) (It is a diagnostic test)

Question 37. Mitsuda reaction is read at:

1. 3rd day
2. 10th day
3. 21st day
4. 45th day

Answer. (3) (21st day)

• Early reading (Fernandez) is taken at 3 days; late reading (Mitsuda reaction) is taken at 3 weeks i.on 21st day.

Question 38. In multibacillary leprosy, after the treatment, follow up is done yearly for:

1. 3 years
2. 5 years
3. 10 years
4. 2 years

Answer. (2) (5 years)

• In multibacillary leprosy, after the treatment, follow up is done yearly for 5 years
• In paucibacillary leprosy, after the treatment, follow up is done yearly for 2 years.

Question 39. Treatment of leprosy according to WHO is done by all except:

1. Dapsone
2. Ciprofloxacin
3. Clofazemine
4. Rifampicin

Answer. (2) (Ciprofloxacin)

• Common drugs given in treatment of leprosy that included in WHO protocol- Dapsone, rifampicin, clofazemine
• Other drugs which can be given in treatment of leprosy- Ethionamide, quinolones, clarithromycin, minocycline.

Question 40. In paucibacillary leprosy, dapsone is continued for:

1. 6 months
2. 9 months
3. 12 months
4. 3 months

Answer. (1) (6 months)

• In paucibacillary leprosy, dapsone is continued for- 6 months
• In multibacillary leprosy, dapsone is continued for- 12 months

Question 41. Lepromin test is valuable for:

1. Diagnosis
2. Response to treatment
3. Epidemiological reason
4. To test humoral immunity

Answer. (2) (Response to treatment)

• Uses of Lepromin test:
  • Classify lesions of leprosy
  • Assess prognosis
  • Assess resistance to leprosy in individuals.

Question 42. Bacteriological index of 1+ indicates:

1. < 100 bacilli/Oil immersion field
2. 1–10 bacilli/100 oil immersion field
3. No Bacilli in all fields
4. Bacilli in all fields

Answer. (2) (1–10 bacilli/100 oil immersion field)

• Bacteriological index:
  • 0 indicates No Bacilli in all fields
  • 1+ indicates – 1–10 bacilli/100 oil immersion field
  • 2+ indicates – 1–10 bacilli/10 oil immersion field
  • 3+ indicates 1–10 bacilli/each oil immersion field
  • 4+ indicates 10–100 bacilli/each oil immersion field
  • 5+ indicates 100–1000 bacilli/each oil immersion field
  • 6+ indicates >1000 bacilli/each oil immersion field
• Morphological index: No. of live bacilli detected by: Solid uniformly stained, parallel sides, rounded ends, length 5 times than width.
• Solid fragmented granular (SFG) percentage of solid fragmented and granular bacilli. It is the most sensitive indicator for monitoring response to treatment.

Question 43. Which is NOT included in Madrid classification but included in indian classification?

1. Inderminate leprosy
2. Borderline leprosy
3. Tuberculoid leprosy
4. Pure neuritic type leprosy

Answer. (4) (Pure neuritic type leprosy)

Classification of leprosy:

• Ridley-Jopling classification TT, BT, BB, BL, LL
• Madrid classification LL, TT, borderline/dimorphous, indeterminate (early unstable type)
• Indian classification Madrid + pure neuritic type

Question 44. Erythema nodosum leprosum (ENL) occur in:

1. Borderline leprosy
2. Lepromatous leprosy
3. Indeterminate type
4. Histoid leprosy
5. Tuberculoid type

Answer. (1, 2) (Borderline leprosy, Lepromatous leprosy)

• Erythema nodosum leprosum (ENL) occurs exclusively in patients near the lepromatous end of the leprosy spectrum (BL-LL), affecting nearly 50% of this group

Question 45. Leprosy affects all except:

1. Testes
2. Ovary
3. Eye
4. Nerve

Answer. (2) (Ovary)

• Grows well in cooler part of body skin, testes, peripheral nerve, anterior eye
• It can involve any organ except CNS and lungs, ovary and also warm area of skin (axilla, groin, scalp)
• LL leprosy, the anterior chamber of the eye is invaded by bacilli, and ENL may result in uveitis, with consequent cataracts and glaucomThus leprosy is a major cause of blindness in the developing world.
• M. leprae invades the testes, and ENL may cause orchitis.
• Tuberculoid leprosy usually affects Peripheral Nerves

Question 46. The following drug is used for the treatment of type II lepra reaction, except:

1. Chloroquine
2. Thalidomide
3. Cyclosporine
4. Corticosteroid

Answer. (3) (Cyclosporine)

Question 47. Which of the following is true regarding globi in a patient with Lepromatous leprosy?

1. Consists of lipid-laden macrophages
2. Consists of macrophages filled with AFB
3. Consists of neutrophils filled with bacteria
4. Consists of activated lymphocytes

Answer. (2) (Consists of macrophages filled with AFB)

‘Intracellularly, M. leprae are arranged as parallel cigar bundles of bacilli bound with lipid like glia (globi) present inside foamy macrophage (Virchow’s leprae cell)’

Question 48. Lupus vulgaris is caused by:

1. M. tuberculosis
2. M. lepare
3. M. ulcerans
4. M. marinum

Answer. (1) (M. tuberculosis)

• Lupus vulgaris (also known as Tuberculosis luposa) are painful cutaneous tuberculosis skin lesions with nodular appearance, most often on the face around the nose, eyelids, lips, cheeks, ears and neck. It is the most common M. tuberculosis skin infection.

Question 49. All are true statement regarding leprosy except:

1. Multibacillary leprosy means person having 6 or more skin lesions
2. Regular MDT means patients received 2/3rd of months of treatment schedule
3. In paucibacillary leprosy > 2 nerves are involved
4. Loss of sensation may present
5. Lepra reaction if not treated can leads to permanent deformities

Answer. (3) (In paucibacillary…)

• Regular multidrug therapy of leprosy means patients should receive atleast 2/3rd of the total duration of treatment schedule (i.at least 8 full months out of 12 months).

Question 50. Leprae bacilli doubling time:

1. 20 hours
2. 20 minutes
3. 12 days

Answer. (3) (12 days)