week 2 medical microbiology

• What is the primary focus of the learning objectives regarding Chlamydia sp.?

  To cover the impact and aetiology of Chlamydia sp (e.g., C. trachomatis)

  
• What is the primary focus of the learning objectives regarding Rickettsia sp.?

  To cover the impact and aetiology of Rickettsia sp (e.g., Rickettsia prowazekii)
• What are the unique life cycles and intracellular survival characteristics of Chlamydia and Rickettsia?


  • Chlamydia:
  • Obligate intracellular pathogens
  • Elementary bodies (EB) and reticular bodies (RB)
  • Rickettsia:
  • Obligate intracellular pathogens
  • Multiply by binary fission in infected cells

  
• What family did Chlamydia sp. and Chlamydophila belong to?

  They once belonged to the same family but now are classified under a single genus: Chlamydia
• What are some examples of Chlamydia species and their associated conditions?

  1. trachomatis (ocular, genital), C. psittaci (psittacosis), C. pneumoniae (10-20% CAP, cardiovascular disease)

  
• What is the significance of the elementary body (EB) in Chlamydia?

  It is the infectious form that is metabolically inactive and approximately 0.2-0.3 microns in diameter
• What is the role of reticular bodies (RB) in Chlamydia's life cycle?

  They are the intracellular reproductive form that is metabolically active and can divide by binary fission
• What is the size range of reticular bodies (RB) in Chlamydia?

  Approximately 0.5-2 microns in diameter
• How do Chlamydia species obtain energy?


  They are energy parasites that lack ATP-generating ability and must obtain ATP from host cells
• How many people are affected by trachoma globally?

  About 1.9 million people are blind or visually impaired due to trachoma
• What does the SAFE strategy stand for in relation to trachoma prevention?


  Surgery, Antibiotics, Facial cleanliness, and Environmental improvement
• How many people received surgery for trachoma in 2018?

  146,112 people received surgery
• What are some examples of fastidious Gram-negative rods?

  • Legionella pneumophila: Legionaire’s Disease
  • Bordetella pertussis: Whooping Cough
  • Haemophilus influenzae: meningitis and septicaemia in children < 6 months

  
• What are some examples of Gram-negative obligate anaerobes?

  • Bacteroides
  • Fusobacterium
  • Prevotella
  • Porphyromonas
• What was the location of the first outbreak of Legionella pneumophila?

  Bellevue-Stratford Hotel, Philadelphia
• What event was occurring when the first outbreak of Legionella pneumophila happened?

  The 58th State Convention of the American Legion of Pennsylvania
• What symptoms did Legionnaires experience during the outbreak?

  Chest pains and breathlessness
• What did the CDC initially fear regarding the outbreak of Legionnaires' disease?

  They feared a terrorist plot
• Who was the rickettsiologist that studied the outbreak in 1977?

  Dr. Joseph McDade
• What did Dr. Carl Fliermans discover about L. pneumophila lipids?

  They resembled those of thermophilic bacteria in Yellowstone National Park
• How many species of Legionella have been characterized?

  42 species
• What is the type species of the genus Legionella?

  Legionella pneumophila
• What percentage of Legionella cases are attributed to Legionella pneumophila?

  85%
• What is the primary mode of transmission for Legionella?

  Inhalation of contaminated aerosols
• What is the incubation period for Legionnaires' disease?

  2 to 10 days
• What is the primary cause of death in Legionnaires' disease?

  Progressive pneumonia with respiratory failure
• What is the typical demographic for reported cases of Legionnaires' disease?

  75–80% are over 50 years and 60–70% are male
• What are the stages of Legionnaires' disease?

  1. Acute pneumonia
  2. Bacterium multiplies in alveolar macrophages
  3. Cytokine production leads to influx of immune cells
  4. Obliteration of air spaces compromises respiratory function
  5. Symptoms: Fevers, cough, breathlessness
• What is the only documented source of Legionella species?

  Water
• Where is Legionella found in the environment?

  In freshwater of streams, lakes, warm springs, rivers, and riverbanks
• What role do amoeba and protozoa play in the life cycle of Legionella?

  They serve as intracellular parasites that protect Legionella against chlorine, drying, and heat
• What factors contribute to Legionella growth in artificial water systems?

  • Temperature
  • Stagnation
  • Nutrients
• What is the chain of causation for Legionella infection?

  1. Environmental Reservoir
  2. Multiplication (stagnation, temperature, nutrients)
  3. Dissemination by aerosol generation
  4. Inhalation into lungs by susceptible host
  5. Aspiration as a common entry method

  
• What is the causative agent of Whooping Cough?

  Bordetella pertussis
• What type of bacteria is Bordetella pertussis?

  Aerobic, Gram-negative, small coccobacillus
• How many people are affected by whooping cough worldwide each year?

  20-40 million people
• What is the incubation period for whooping cough?

  1. 10 days
• What are the stages of whooping cough?

  1. Catarrhal stage: 1-2 weeks of rhinorrhoea and mild cough
  2. Paroxysmal stage: 1-6 weeks of forceful coughing, whoop sound, vomiting
  3. Complications: pneumonia, otitis media, asthma
• What factors contribute to the epidemiology of Bordetella pertussis?

  Increased awareness, better detection methods, waning immunity, and acellular vaccines
• What are some clinical diseases associated with Gram-negative obligate anaerobes?

  • Periodontal infections
  • Abscess
  • Intra-abdominal infections
  • Gynecological infections
  • Skin and soft tissue infections