Mycobacterium

• What is the primary pathogenic mycobacterium discussed in the study material?

  1. tuberculosis
• Why is it important to understand pathogenic mycobacteria?

  They are significant causes of disease in humans.
• What are the key processes involved in the pathogenesis of mycobacteria?

  • Establishment of infection
  • Progression to disease
  • Transmission
• What is the shape and structure of mycobacteria?

  They are unicellular and branched rods.
• What type of staining is used for mycobacteria?

  Acid-fast staining.
• What is the Ziehl-Neelsen stain used for?

  To stain mycobacteria.

  
• What are the steps involved in the Ziehl-Neelsen staining process?

  1. Stain with carbol fuchsin.
  2. Destain with acid alcohol.
  3. Counterstain with methylene blue.

  
• What color do mycobacteria stain in the Ziehl-Neelsen method?

  Red.

  
• What is the significance of mycolic acid in mycobacteria?

  It contributes to the waxy cell wall, making them acid-fast.
• How are mycobacteria classified based on their growth rate?

  • Fast growers: 1-2 days on plates (e.g., M. phlei, M. smegmatis).
  • Slow growers: several weeks to months (e.g., M. tuberculosis).
• Which mycobacterium is closely related to tuberculosis and poses a zoonotic risk?

  1. bovis.
• What disease does M. avium-intracellulare cause in humans?

  It is an opportunistic infection, especially common in HIV patients.
• What disease is caused by M. leprae?

  Leprosy.
• What is the global impact of tuberculosis?

  30,000 people die every week, and 2 billion are infected.
• What are the common clinical manifestations of tuberculosis?

  Fever, weight loss, weakness, persistent cough.
• What are the potential sites of TB infection in the body?

  • Central nervous system
  • Lymphatic system
  • Genitourinary system
  • Bones and joints
• What happens to most people after a TB infection?

  They control the infection and may develop asymptomatic latent infection.
• How does M. tuberculosis enter the body?

  Through aerosols that travel to the alveoli of the lungs.
• What is the role of alveolar macrophages in TB infection?

  They engulf M. tuberculosis and can either clear or contain the infection.
• What is the granulomatous response in TB infection?

  • Attracts more immune cells.
  • Damages tissue and forms granulomatous tubercle.
  • Can lead to latent infection.
• What can happen if the granulomatous response fails to contain the bacteria?

  It can lead to reactivation of the infection.
• What is the significance of the immune response in TB transmission?

  It is required for transmission and can damage the host.
• What is the primary method of diagnosing TB?

  Microscopy of sputum for acid-fast rods.
• What is the culture medium used for growing mycobacteria?

  Lowenstein-Jensen medium.
• What is the role of PCR in TB diagnosis?

  It detects the presence of TB DNA.
• What are the control strategies for TB?

  • Preventive vaccination.
  • Antibiotic treatment.
  • Diagnosis.
• What is the purpose of the BCG vaccine?

  To prevent establishment of TB infection and disease.
• What is the efficacy of the BCG vaccine in children?

  It protects against disseminated disease.
• What is the challenge with treating the 2 billion people with asymptomatic TB infection?

  They cannot be treated effectively due to the lack of symptoms.
• What are the first-line oral anti-TB drugs?

  • Isoniazid
  • Rifampicin
  • Ethambutol
  • Pyrazinamide
• Why is multi-drug treatment required for TB?

  To prevent resistance development in bacteria.
• What is the definition of MDR-TB?

  Resistant to at least rifampicin and isoniazid.
• What is XDR-TB?

  Resistant to rifampicin, isoniazid, any fluoroquinolone, and at least one injectable second-line drug.
• What is the treatment regimen for MDR-TB?

  • At least 4 potentially active drugs.
  • New drugs like Bedaquiline and Delaminid.
  • Repurposed drugs like Linezolid and moxifloxacin.
• What is the global success rate for treating MDR-TB?

  55%.
• What is the causative agent of leprosy?

  1. leprae.
• How can M. leprae be cultured for study?

  In 9-banded armadillos and mouse footpads.
• What percentage of individuals infected with leprosy develop clinical disease?

  5%.
• What are the two clinical manifestations of leprosy?

  • Tuberculoid: mild disease with few bacilli.
  • Lepromatous: severe disease with many bacilli.
• What is the primary treatment for lepromatous leprosy?

  Dapsone.