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• What are actinomycetes?

  Slender, filamentous, fungal-like organisms
• How do actinomycetes appear microscopically?

  As filamentous rods that may fragment

  
• What is the Gram stain characteristic of actinomycetes?

  Gram positive

  
• Which genus of actinomycetes is both Gram-positive and weakly acid-fast?

  Genus Nocardia

  
• Are actinomycetes motile or non-motile?

  Non-motile
• Do actinomycetes form spores?

  No, they are non-spore forming
• What is the classification of actinomycetes based on their growth conditions?

  • Anaerobic actinomycetes:
  • Actinomyces
  • Bifidobacterium
  • Eubacterium
  • Aerobic actinomycetes:
  • Nocardia
  • Streptomyces
  • Actinomadura

  
• Name three species of Actinomyces.

  1. A.israelii, A. viscosus, A. meyeri
• What type of bacteria are Actinomyces species?

  Anaerobic Gram-positive bacteria

  (facultative anaerobes or strict anaerobes)

  
• How do Actinomyces grow in culture?

  They grow slowly in culture
• Where are Actinomyces commonly found in the human body?

  In the oropharynx, GIT, urogenital tract
• What forms do Actinomyces develop in clinical specimens?

  Delicate filamentous forms or hyphae

  
• How do Actinomyces reproduce?

  By fission
• What type of infections do Actinomyces produce?

  Chronic, slowly developing infections

  
• What are the clinical manifestations of actinomycosis?

  1. Cervicofacial actinomycosis

  • 'Lumpy jaw syndrome'
  • Large abscesses
  • Mandibular osteomyelitis

  1. GUT actinomycosis

  • Pelvic actinomycosis in women using IUD

  1. Respiratory tract actinomycosis

  • Pulmonary, bronchial, laryngeal infections

  1. Extrafacial bone and joint actinomycosis
  2. CNS actinomycosis

  • Brain abscess

  3. GIT actinomycosis

  
• What is the most frequent clinical form of actinomycosis?

  Cervicofacial actinomycosis

  
• What is another name for cervicofacial actinomycosis?

  'Lumpy jaw syndrome'
• What are the predisposing conditions for cervicofacial actinomycosis?

  Poor oral hygiene and oral mucosa trauma

  
• What is the presentation of cervicofacial actinomycosis?

  Slowly progressive painless mass

  
• What is the second most frequent clinical form of actinomycosis?

  GUT actinomycosis

  
• What is a common presentation of GUT actinomycosis?

  Genital mass +/- fever

  
• What are the common causes of respiratory tract actinomycosis?

  Aspiration and poor oral hygiene

  
• What are the clinical manifestations of respiratory tract actinomycosis?

  Mild fever, weight loss, productive cough

  
• What is the pathology of actinomycosis characterized by?

  Chronic granulomatous infection with sulfur granules

  
• What is the size of sulfur granules in actinomycosis?

  0.1-1 mm diameter
• What is the purpose of the protein-polysaccharide complex in actinomycosis?

  To inhibit phagocytosis
• What are the laboratory diagnosis methods for actinomycosis?

  • Specimen collection: abscess content, sinus discharge
  • Culture on BA
  • Slow growth: 5-20 days at 35-37°C
  • Gram stain: Gram-positive branching filamentous rods
• What is the treatment for actinomycosis?

  Drainage and penicillin (DOC)

  Carbapenems, macrolides and clindamycin
• What are the normal microbiota of the GIT?

  Bifidobacterium and Eubacterium

  
• What are the characteristics of Nocardia species?

  Gram-positive bacilli, strict aerobes

  
• How are Nocardia species transmitted?

  By inhalation of airborne spores or mycelial fragments from environmental species
• What are the virulence factors of Nocardia?

  Ability to resist phagocytosis

  Catalase and superoxide dismutase

  Able to survive and replicate in macrophages;

  (1) preventing fusion of the phagosome-lysosome (mediated by cord factor ) ‘

  (2) preventing acidification of the phagosome, and

  (3) avoiding acid phosphatase—mediated killing by metabolic utilization of the enzyme as a carbon.
• What are the clinical manifestations of pulmonary nocardiosis?

  Cough, thick purulent sputum, fever

  
• What is primary cutaneous disease caused by Nocardia?

  Lymphocutaneous infection and localized abscess
• What are the laboratory diagnosis methods for Nocardia?

  • Specimen collection: bronchial washings, sputum
  • Gram stain/modified acid-fast stains
  • Culture on non-selective media
• What is the treatment for Nocardia infections?

  Trimethoprim-Sulfamethoxazole

  Amikacin

  Ceftriaxone

  Imipenem

  Combination therapy in serious disease, CNS and dissemination
• What are the characteristics of Streptomyces?

  Saprophytic soil organisms causing mycetoma

  
• What is the role of Actinomadura in infections?

  Causes mycetoma

  
• What are the common features of aerobic actinomycetes?

  • Nocardia
  • Streptomyces
  • Actinomadura
  • Gram-positive
  • Branching hyphae

  
• What are the predisposing factors to clinical manifestations of nocardia?

  1.Underlying chronic lung disease e.g. COPD, asthma

  2.Drug-induced systemic immunosuppression

  3.Chronic granulomatous disease

  4.Diabetes

  5.HIV