Tuberculosis and Mycobacterial Diseases — MCQs
Phagocytosis of mycobacterium tuberculosis by macrophages is mainly mediated by:
XDR means extensive drug resistance to
A poverty-stricken mother suffering from active tuberculosis delivers a baby. Which one of the following would be the most appropriate advice in her case?
Mycobacterium tuberculosis having resistance to rifampicin, isoniazid, and pyrazinamide is described as -
Which one of the following statements is true regarding the pathogenicity of Mycobacteria species?
Most common extra pulmonary involvement of TB ?
A 45-year-old HIV-positive man presents with fever and cough. Sputum culture shows acid-fast bacilli. Which of the following drugs is essential in the treatment regimen?
What should you do next for a 35-year-old man who is positive for HBsAg and HBeAg, discovered incidentally during blood donation screening, with normal SGOT and SGPT laboratory values?
Devi, a 28 year female, has diarrhea, confusion, high grade fever with bilateral pneumonitis. The diagnosis is -
All the following are causes of a painful limp, except which of the following?
Tuberculosis and Mycobacterial Diseases Indian Medical PG Practice Questions and MCQs
Question 1: Phagocytosis of mycobacterium tuberculosis by macrophages is mainly mediated by:
- A. Interleukin 6
- B. Interleukin 3
- C. Interleukin 12
- D. Interferon Gamma (Correct Answer)
Explanation: ***Interferon Gamma*** - **Interferon gamma (IFN-γ)** is the most critical cytokine for **macrophage activation** in tuberculosis, enabling effective phagocytosis and intracellular killing of **Mycobacterium tuberculosis**. - IFN-γ (produced by **Th1 cells** and **NK cells**) primes macrophages by: - Enhancing **phagosome-lysosome fusion** - Increasing expression of **Fc receptors** and **complement receptors** for better opsonization - Stimulating production of **reactive oxygen species (ROS)** and **nitric oxide (NO)** - Upregulating **MHC class II** for improved antigen presentation - Without IFN-γ, macrophages cannot effectively control intracellular mycobacterial growth (as seen in **IFN-γ or IL-12 receptor deficiencies** leading to disseminated mycobacterial infections). *Interleukin 6* - **IL-6** is a pro-inflammatory cytokine involved in **acute-phase responses**, fever induction, and B-cell differentiation. - While it contributes to systemic inflammatory responses in TB, it does not directly activate macrophages for mycobacterial phagocytosis and killing. *Interleukin 3* - **IL-3** is a **hematopoietic growth factor** that promotes proliferation and differentiation of myeloid and lymphoid progenitor cells in bone marrow. - It plays no direct role in the effector functions of mature macrophages against *M. tuberculosis*. *Interleukin 12* - **IL-12** (produced by macrophages and dendritic cells) is essential for initiating **Th1 immunity** by promoting differentiation of naive CD4+ T cells into **Th1 cells** that produce IFN-γ. - IL-12 acts **upstream** of IFN-γ in the immune cascade but does not directly mediate macrophage phagocytic function. - The **IL-12/IFN-γ axis** is critical for TB immunity, but IFN-γ is the direct macrophage activator.
Question 2: XDR means extensive drug resistance to
- A. Minimum of 1 injectable drug
- B. H+R
- C. 1 Fluoroquinolone
- D. Fluoroquinolone + at least one Group A drug (bedaquiline/linezolid) (Correct Answer)
Explanation: ***Fluoroquinolone + at least one Group A drug (bedaquiline/linezolid)*** - **Extensively drug-resistant (XDR) tuberculosis** is defined by the WHO (2021) as TB with resistance to **rifampicin** (RR-TB baseline), plus resistance to any **fluoroquinolone** (levofloxacin or moxifloxacin), plus resistance to at least one additional **Group A drug** (bedaquiline or linezolid). - This represents the current standard definition emphasizing resistance to the most critical second-line oral agents. - XDR-TB is built upon **MDR-TB** (H+R resistance) with additional resistance patterns that make treatment extremely challenging. *Minimum of 1 injectable drug* - Injectable drug resistance (aminoglycosides, capreomycin) was part of the **old XDR-TB definition** (pre-2021) but is no longer required. - The WHO updated the definition to focus on more effective oral drugs rather than injectables. *H+R* - Resistance to **isoniazid (H)** and **rifampicin (R)** defines **multidrug-resistant (MDR) tuberculosis**, not XDR-TB. - MDR-TB is the foundation upon which XDR-TB is built, but it represents a less severe form of drug resistance. *1 Fluoroquinolone* - While fluoroquinolone resistance is a **necessary component** of XDR-TB, it is **not sufficient alone**. - XDR-TB requires fluoroquinolone resistance **plus** additional resistance to Group A drugs (bedaquiline or linezolid).
Question 3: A poverty-stricken mother suffering from active tuberculosis delivers a baby. Which one of the following would be the most appropriate advice in her case?
- A. Breast feeding and BCG immunization
- B. Breast feeding and isoniazid administration (Correct Answer)
- C. Expressed breast milk and BCG immunization
- D. Stop feeds and isoniazid administration
Explanation: ***Breast feeding and isoniazid administration*** - **Breastfeeding** is safe and encouraged for infants of mothers with active tuberculosis, as the benefits of breast milk (nutrition, antibodies) outweigh the minimal risk of TB transmission through milk. - **Isoniazid (INH) chemoprophylaxis** for the infant provides additional protection in high-risk exposure settings, particularly when the mother has active pulmonary TB and close contact is inevitable. - This approach represents a conservative strategy prioritizing immediate chemoprophylaxis in a poverty-stricken setting where follow-up may be challenging. *Breast feeding and BCG immunization* - **Breastfeeding** is beneficial and appropriate. - **BCG immunization** at birth is the current standard recommendation per WHO and IAP guidelines for infants born to TB-positive mothers. - However, in settings with very high exposure risk and uncertain follow-up, some protocols additionally recommend INH prophylaxis, making the first option more comprehensive for this specific scenario. *Expressed breast milk and BCG immunization* - Expressing breast milk offers no significant additional protection against TB transmission compared to direct breastfeeding. - Direct breastfeeding has additional benefits for mother-infant bonding and is not contraindicated in maternal TB. - While **BCG immunization** is appropriate, this option unnecessarily complicates feeding. *Stop feeds and isoniazid administration* - **Stopping breastfeeding** is not indicated and would deprive the infant of essential nutrition and passive immunity. - Breastfeeding is not contraindicated in maternal tuberculosis. - While **isoniazid administration** may be appropriate, cessation of feeding is an incorrect recommendation.
Question 4: Mycobacterium tuberculosis having resistance to rifampicin, isoniazid, and pyrazinamide is described as -
- A. Drug resistant tuberculosis
- B. Extremely drug resistant tuberculosis
- C. Multi drug resistant tuberculosis (Correct Answer)
- D. None of the options
Explanation: ***Multi drug resistant tuberculosis*** - This classification specifically refers to *Mycobacterium tuberculosis* resistant to at least **rifampicin** and **isoniazid**, which are the two most potent first-line anti-TB drugs. - While resistance to **pyrazinamide** is also present in this case, the definition of multidrug-resistant tuberculosis (MDR-TB) primarily hinges on resistance to these two core drugs [1]. *Drug resistant tuberculosis* - This is a broad term that can apply to any resistance to one or more anti-TB drugs, but it is not specific enough for resistance to these crucial first-line agents [1]. - It does not convey the clinical and public health implications of resistance to both rifampicin and isoniazid. *Extremely drug resistant tuberculosis* - **Extensively drug-resistant tuberculosis (XDR-TB)** is defined as MDR-TB (resistance to rifampicin and isoniazid) plus resistance to any **fluoroquinolone** and at least one of the three injectable second-line drugs (amikacin, kanamycin, or capreomycin). - The given resistance pattern does not include fluoroquinolones or injectable second-line drugs. *None of the options* - This option is incorrect because the resistance pattern described perfectly fits the definition of multidrug-resistant tuberculosis.
Question 5: Which one of the following statements is true regarding the pathogenicity of Mycobacteria species?
- A. M. Africanum is typically contracted from humans or monkeys.
- B. M. marinum is primarily associated with skin infections. (Correct Answer)
- C. M. Kansasii is primarily an environmental organism that rarely causes human disease.
- D. M. tuberculosis and M. bovis have distinct pathogenic profiles in humans.
Explanation: ****M. marinum is primarily associated with skin infections.**** - *Mycobacterium marinum* is famously associated with "fish tank granuloma" or "swimming pool granuloma," causing **cutaneous lesions** following exposure to contaminated water. - Infection typically occurs through breaks in the skin from contact with infected fish, aquariums, or other aquatic environments. *M. Kansasii is primarily an environmental organism that rarely causes human disease.* - While *M. kansasii* is an environmental organism, it is a significant cause of **nontuberculous mycobacterial lung disease** in humans, resembling tuberculosis. - It does not rarely cause human disease; it's one of the more common causes of atypical mycobacterial infections. *M. Africanum is typically contracted from humans or monkeys.* - *M. africanum* is a species of *Mycobacterium tuberculosis* complex (MTBC) and is primarily a pathogen of **humans**, particularly in parts of West and East Africa. - It is **not typically contracted from monkeys**; the primary reservoir for *M. africanum* is humans. *M. tuberculosis and M. bovis have distinct pathogenic profiles in humans.* - Both *M. tuberculosis* and *M. bovis* are members of the MTBC and cause **tuberculosis in humans**, with *M. bovis* traditionally transmitted through contaminated dairy products. - While *M. tuberculosis* is the primary cause of human TB and *M. bovis* can cause extrapulmonary and pulmonary disease, their pathogenic profiles in humans are often **similar** in presentation with respect to the disease they cause, though modes of transmission differ.
Question 6: Most common extra pulmonary involvement of TB ?
- A. Bone
- B. Ileocecal
- C. Lymph nodes (Correct Answer)
- D. Pleura
Explanation: ***Bone*** - While **skeletal tuberculosis** can occur, particularly in the spine (**Pott's disease**), it is not the most common extrapulmonary manifestation [2]. - Bone involvement typically presents with localized pain, swelling, and sometimes neurological deficits [2]. *Ileocecal* - **Gastrointestinal TB**, especially involving the **ileocecal region**, is a significant form of extrapulmonary TB. - It often leads to abdominal pain, weight loss, and malabsorption, but it is less common than lymph node involvement. *Lymph nodes* - **Tuberculous lymphadenitis** (scrofula) is the **most common extrapulmonary manifestation of TB**, especially in immunocompetent individuals and children [1]. - Typically presents as painless, slowly enlarging lymph nodes, most often in the cervical region [1]. *Pleura* - **Pleural effusion** (tuberculous pleurisy) is a common manifestation of TB and involves the lining of the lungs. - Although frequent, it is generally considered a **pulmonary complication** or a contiguous spread from the lung rather than a distinctly extrapulmonary site like the lymph nodes.
Question 7: A 45-year-old HIV-positive man presents with fever and cough. Sputum culture shows acid-fast bacilli. Which of the following drugs is essential in the treatment regimen?
- A. Doxycycline
- B. Amoxicillin
- C. Isoniazid (Correct Answer)
- D. Ciprofloxacin
Explanation: ***Isoniazid*** - The presence of **acid-fast bacilli** (AFB) in sputum, especially in an **HIV-positive** individual with fever and cough, strongly indicates **tuberculosis (TB)** [1]. - **Isoniazid** is a cornerstone drug in **first-line anti-tuberculosis therapy** and is essential for effective treatment [1]. *Doxycycline* - **Doxycycline** is a tetracycline antibiotic primarily used for bacterial infections like **atypical pneumonia**, Lyme disease, and certain sexually transmitted infections. - It has **no significant activity against Mycobacterium tuberculosis** and is not part of TB treatment. *Amoxicillin* - **Amoxicillin** is a penicillin-class antibiotic effective against a range of common bacterial infections, but it is **ineffective against mycobacteria**. - It would not be used to treat **tuberculosis**. *Ciprofloxacin* - **Ciprofloxacin** is a fluoroquinolone antibiotic used for various bacterial infections, including some respiratory and urinary tract infections. - While some fluoroquinolones are used as **second-line agents** in specific multi-drug resistant TB regimens, **ciprofloxacin** is not a first-line drug and is generally reserved for particular circumstances, unlike isoniazid which is essential for initial therapy.
Question 8: What should you do next for a 35-year-old man who is positive for HBsAg and HBeAg, discovered incidentally during blood donation screening, with normal SGOT and SGPT laboratory values?
- A. HBV-DNA estimation (Correct Answer)
- B. Observation
- C. Liver biopsy
- D. Interferon therapy
Explanation: ***HBV-DNA estimation*** - The presence of **HBsAg** and **HBeAg** indicates **active viral replication**, necessitating quantification of HBV-DNA to assess viral load [1]. - Normal SGOT and SGPT suggest compensated liver function, but **viral load** is crucial for staging the disease and guiding future management [1]. *Observation* - While liver enzymes are normal, the presence of **HBsAg** and **HBeAg** indicates active hepatitis B infection, which warrants further investigation, not just observation [1]. - Undiagnosed and untreated chronic hepatitis B can lead to serious complications such as **cirrhosis** and **hepatocellular carcinoma** [1]. *Liver biopsy* - **Liver biopsy** is an invasive procedure typically reserved for cases where histological assessment is required to confirm **fibrosis** or **inflammation severity**, or when there's discordance between viral markers and clinical presentation. - It's not the initial step for a patient with normal transaminases and clear serological markers of active infection; **HBV-DNA estimation** is generally performed first [1]. *Interferon therapy* - **Interferon therapy** is a treatment for chronic hepatitis B, but initiating treatment requires a comprehensive assessment including **HBV-DNA levels**, in addition to liver enzyme levels and evaluation of liver damage [2]. - It would be premature to consider treatment without a **viral load** measurement and a full workup to determine the phase of infection and the need for therapy [2].
Question 9: Devi, a 28 year female, has diarrhea, confusion, high grade fever with bilateral pneumonitis. The diagnosis is -
- A. H. influenzae
- B. Legionella (Correct Answer)
- C. Streptococcus pneumoniae
- D. Neisseria meningitidis
Explanation: ***Legionella*** - The constellation of **diarrhea, confusion (neurological symptoms), high-grade fever, and bilateral pneumonitis** is highly characteristic of **Legionnaires' disease**, caused by *Legionella pneumophila* [1]. - This organism commonly causes **extrapulmonary symptoms** such as gastrointestinal and neurological manifestations, in addition to severe pneumonia. *H. influenzae* - While *H. influenzae* can cause pneumonia, it typically presents with **lobar pneumonia** [1] and rarely involves gastrointestinal or significant neurological symptoms beyond general debility. - It is more commonly associated with **epiglottitis** and **meningitis** in unimmunized children. *Streptococcus pneumoniae* - *Streptococcus pneumoniae* is the most common cause of **community-acquired pneumonia**, often presenting with acute onset of fever, chills, and productive cough [1]. - While it can cause bacteremia and sepsis, **gastrointestinal symptoms like prominent diarrhea and significant neurological confusion** are not typical primary features of pneumococcal pneumonia. *Neisseria meningitidis* - *Neisseria meningitidis* is primarily known for causing **meningitis** and **meningococcemia**, involving symptoms like stiff neck, headache, rash, and fever [1]. - While it can sometimes cause pneumonia, the combination with **prominent diarrhea and severe, bilateral pneumonitis** as the primary presentation is not characteristic; the neurological symptoms point more towards Legionella given the other features.
Question 10: All the following are causes of a painful limp, except which of the following?
- A. Slipped femoral epiphysis (SCFE)
- B. Tuberculosis (TB) of the hip
- C. Perthes disease (Legg-Calvé-Perthes disease)
- D. Infantile Coxa Vara (Coxa Vara) (Correct Answer)
Explanation: ***Infantile Coxa Vara (Coxa Vara)*** - **Infantile coxa vara** is a developmental condition characterized by a **reduced femoral neck-shaft angle**, often leading to a painless waddling gait or limp. - While it causes a limp, the limp itself is typically **painless**, distinguishing it from the other conditions listed. *Slipped femoral epiphysis (SCFE)* - **SCFE** involves displacement of the **femoral head** from the neck through the growth plate and is a classic cause of a **painful limp** in adolescents, often associated with obesity. - Patients typically experience **hip, groin, thigh, or knee pain** and may present with a shortened leg with external rotation. *Tuberculosis (TB) of the hip* - **TB of the hip** is a chronic infectious arthritis that causes significant **pain**, swelling, and reduced range of motion, leading to a **painful limp**. - It often presents insidiously with **constitutional symptoms** like fever and weight loss, in addition to localized pain. *Perthes disease (Legg-Calvé-Perthes disease)* - **Perthes disease** is characterized by avascular necrosis of the **femoral head** in children, causing a **painful limp** and restricted hip movement. - The pain typically worsens with activity and improves with rest, and may be referred to the knee or thigh.
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