Mycobacterium 1

• What shape are mycobacteria?

  Thin, rod-shaped
• What type of aerobes are mycobacteria?

  Obligate aerobes
• Why are mycobacteria difficult to stain?

  They have a complex cell wall composed of long chain fatty acids called (mycolic acid) and other lipids and waxes
• What is the main fatty acid found in the cell wall of mycobacteria?

  Mycolic acid
• What staining method cannot be used for mycobacteria?

  Gram stain
• What is the classification basis for mycobacteria?

  Nutritional requirement, growth rate, and pigment production
• Name one species in the Mycobacterium tuberculosis complex.

  Mycobacterium tuberculosis
• What are photochromogens?

  Mycobacteria that produce pigment in the presence of light
• Which mycobacterium is classified as a scotochromogen?

  Mycobacterium scrofulaceum
• What is the growth rate of Mycobacterium leprae?

  Non-grower
• What percentage of the cell wall of Mycobacterium tuberculosis is made up of mycolic acid?

  60%
• What does the hydrophobic cell wall of mycobacteria render them resistant to?

  Staining, disinfectants, dryness, acid, and alkalis
• What is the growth pattern of virulent strains of Mycobacterium tuberculosis?

  Serpentine cord-like growth pattern
• What is the global prevalence of Mycobacterium tuberculosis infection?

  1 in 3 individuals is infected
• What factors contributed to the rise of tuberculosis in western countries in the mid-1980s?

  HIV/AIDS pandemic, increased immigration, increased homelessness, and increased drug abuse
• How is tuberculosis primarily transmitted?

  Inhalation of aerosol droplets
• What happens during the primary infection of tuberculosis?

  The inhaled bacilli are engulfed by alveolar macrophages
• What are the two types of lesions that can occur during primary tuberculosis infection?

  Exudative lesions and granulomatous lesions
• What is a Ghon focus?

  A 1- to 1.5-cm area of gray-white inflammatory consolidation
• Where are tubercles typically found during primary infection?

  In alveoli and subpleural region
• What is the fate of tubercles in tuberculosis?

  Healing by fibrosis or calcification
• What is miliary tuberculosis?

  Haematogenous widespread seeding of Mycobacterium tuberculosis to various organs
• What is the role of cell-mediated immunity in tuberculosis?

  It helps to control the infection by responding to mycobacterial proteins
• What are common clinical manifestations of pulmonary tuberculosis?

  Low-grade fever, cough, night sweating, and weight loss
• What is sterile pyuria in tuberculous pyelonephritis?

  Urine contains leukocytes with negative results on standard culture techniques
• What is the Mantoux test used for?

  To diagnose tuberculosis infection
• What does a positive Mantoux test indicate?

  Active disease, past exposure, or vaccination
• What are the first-line drugs for tuberculosis treatment?

  Isoniazid, rifampicin, pyrazinamide, ethambutol, and streptomycin
• What is the purpose of directly observed therapy-short course (DOTS)?

  To ensure adherence to tuberculosis treatment
• What are the categories for tuberculosis diagnosis?

  • Radiological
  • Haematological
  • Bacteriological
  • Immunological
• What are the methods used in bacteriological diagnosis of tuberculosis?

  • Specimen collection (sputum, CSF, urine)
  • Staining (Ziehl-Neelsen stain, fluorescent stain)
  • Culture (Löwenstein Jensen Medium, automated culture)
• What are the second-line drugs for tuberculosis treatment?

  • Ethionamide
  • Paraaminosalicylic acid
  • Cycloserine
  • Capreomycin
  • Amikacin
  • Ciprofloxacin
  • Azithromycin
• What are the types of resistance in tuberculosis?

  • Single drug resistance
  • Multidrug resistance (MDR)
  • Extensive drug resistance (XDR)
• What is the BCG vaccine?

  • Live attenuated vaccine derived from Mycobacterium bovis
  • Recommended for all newborns (0-7 days)
  • Provides <80% protection
• The genus Mycobacterium is divided into four groups based on their growth rate at 37°C (slow growers) and the presence/absence of pigmentation (pigmented)
• Mycobacteria are acid-fast, nonmotile, aerobic or facultative anaerobes
• Mycobacteria can be identified by their morphologic characteristics such as size, shape, staining properties, and arrangement.