Actinomycetes and Nocardia

• What are the two types of fungi-like bacteria discussed in the lecture?


  Actinomyces and Nocardia
• What are the lecture objectives regarding Actinomyces and Nocardia?

  • Describe microscopic and colonial morphologies
  • Describe major clinical infections associated
  • Describe infection control and management
• How do Actinomyces and Nocardia resemble fungi?

  They develop filamentous hyphae.

  
• What is the typical bacterial cell wall composition?

  It contains muramic acid and lacks a nuclear membrane.

  
• What type of infections do Actinomyces typically produce?

  Chronic, slowly developing infections.
• What type of organism is Actinomyces?

  Gram positive beaded, filamentous anaerobic organism.
• Where does Actinomyces typically grow as normal flora?

  In the mouth and female genital tract.

  
• What are the major pathogens of Actinomyces?

  • A. israelii – causes actinomycosis in humans
  • A. odontolyticus – found in the human mouth

  
• What is the optimum growth temperature for Actinomyces?

  37c
• What type of medium do Actinomyces grow best in?

  Medium containing blood, glucose, and glycerol.

  
• How long does it take for Actinomyces to show tiny colonies?

  1. 4 days.
• What are the characteristics of Actinomyces colonies on blood agar?

  • Raised, nodular, cream-colored
  • Described as molar tooth colonies
  • Temperature sensitive: killed at 60°C for 15 minutes

  
• What is actinomycosis?

  A chronic granulomatous infection of endogenous origin.

  
• Where are Actinomyces typically found in the body?

  In the mouth, carious teeth, dental plaque, and tonsillar crypts.

  
• How do Actinomyces cause disease?

  By crossing the epithelial barrier into tissue with low O2 tension.
• What are the major clinical types of actinomycosis?

  • Cervicofacial (most common)
  • Thoracic & abdominal (uncommon)
  • Pelvic (associated with intrauterine devices)

  
• What is the most common type of actinomycosis?

  Cervicofacial actinomycosis.
• What causes cervicofacial actinomycosis?

  Poor dental hygiene and tooth extraction.

  
• What are the symptoms of cervicofacial actinomycosis?

  Hard tender swelling that drains pus through sinus tracts.

  
• What complications can arise from cervicofacial actinomycosis?

  Involvement of bone, particularly the mandible.

  
• What is thoracic actinomycosis associated with?

  Aspiration and carious teeth.

  
• What are the symptoms of thoracic actinomycosis?


  Fever, cough, and dyspnoea.

  
• What is the primary lesion location in abdominal actinomycosis?

  Appendix, caecum, or pelvic organs.

  
• What are the symptoms of abdominal actinomycosis?


  Pain in the ileocaecal region, fever, chills, vomiting, intestinal colic, and weight loss.
• What is the role of Actinomyces in the female genital tract?

  They are normal flora and can be associated with IUCD and genital tract infections.
• What specimens are used for laboratory diagnosis of Actinomyces?

  • Swabs from discharges
  • Sputum
  • Blood
  • CSF (when appropriate)
  • Tissue biopsy (curettings of uterus)

  
• How can sulfur granules be observed macroscopically?


  By shaking pus with water in a test tube to form a deposit.

  
• What is the significance of sulfur granules in diagnosis?

  The presence of sulfur granules is adequate for diagnosis.

  
• What is the appearance of sulfur granules under microscopy?


  Yellowish to dark brown with branching coccoid/bacillary forms.

  
• What culture conditions improve the growth of Actinomyces?

  CO2 improves growth on blood agar.

  
• What is the appearance of colonies after 3-5 days of culturing Actinomyces?

  A 1 mm white "Spider" colony, a mass of branching filaments.
• What is the treatment for Actinomyces infections?

  • Penicillin G in large doses for 2-3 months
  • Followed by oral Penicillin
  • Follow up for up to 1 year
  • Surgery for extensive granuloma formation

  
• What should be done if a patient is allergic to penicillin?

  Tetracycline or sulphonamides can be used, and sometimes streptomycin in combination with penicillin.
• What are the prevention strategies for Actinomyces infections?


  • Prevention of dental caries
  • Early and adequate treatment of caries
• What type of bacteria is Nocardia?

  Aerobic Gram positive branching bacilli.

  
• What is the habitat of Nocardia?

  They are saprophytes in the soil.

  
• What are the major pathogens of Nocardia?

  N. asteroides complex and N. brasiliensis.

  
• What diseases are associated with Nocardia?

  Pulmonary disease and madura foot (mycetoma).
• How does Nocardia typically infect the body?

  Through inhalation or direct inoculation following minor trauma.
• What are the risk factors for Nocardia infections?


  Immunosuppression, organ transplant, corticosteroid treatment, and AIDS.