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10 aerobic actinomycetes-and_anaerobic_____actinomyces_v1-_3

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  • 1. Aerobic Actinomycetes and Anaerobic Actinomyces Dr. John R. Warren Department of Pathology Northwestern University Feinberg School of Medicine June 2007
  • 2. Taxonomy of the Aerobic Actinomycetes
    • Gram-positive branching filaments that sporulate or fragment: the aerobic
    • Actinomycetes (order Actinomycetales )
    • Aerobic Actinomycetes whose cell walls contain mycolic acid: Nocardia species and Rhodococcus species (family Nocardiaceae )
    • Aerobic Actinomycetes whose cell walls lack mycolic acid: Streptomyces species
  • 3. Taxonomy of the Anaerobic Actinomyces
    • Anaerobic non-sporulating gram-positive rods consist of two groups based on guanosine (G) plus cytosine (C) DNA content: Low mole percent (30-53%) and high mole percent (49-68%)
    • Actinomyces species member of the high G+C group
  • 4. Taxonomy of the Aerobic Actinomycetes : Pathogenic Genera
    • Nocardia
    • Actinomadura
    • Streptomyces
    • Rhodococcus
    • Gordonia
    • Tsukamurella
    • Tropheryma whipplei (Non-cultivable)
  • 5. Aerobic Actinomycetes : Natural Habitats
    • Nocardia species and other aerobic
    • Actinomycetes ubiquitous in soil and primarily responsible for decomposition of organic plant matter
    • Rhodococcus species present in the intestinal bacterial flora of grazing herbivores especially horses
    • Streptomyces species (>3,000) widely distributed in soil
  • 6. Anaerobic Actinomyces : Natural Habitats
    • Anaerobic Actinomyces species
    • are normal inhabitants of the
    • mucous membranes of humans
    • and animals
  • 7. Aerobic Actinomycetes : Modes of Infection
    • Nocardia infection acquired by inhalation of or direct skin inoculation (traumatic) by environmental organisms
    • Rhodococcus infection due primarily to inhalation of organisms by animal handlers (horses, pigs, cattle)
    • Streptomyces are soil organisms that can infect traumatic wounds especially of the feet
  • 8. Aerobic Actinomycetes : Modes of Infection
    • Actinomadura species ( A. madurae, A. latina, A. pelletieri ) produce subcutaneous infections in tropical and subtropical countries with those who walk barefooted
    • Gordonia and Tsukamurella species are closely related to Rhodococcus , and are soil organisms considered opportunistic pathogens
  • 9. Anaerobic Actinomyces : Modes of Infection
    • Actinomyces invades normally
    • sterile tissue from endogenous
    • mucous membrane sites of
    • normal colonization
  • 10. Aerobic Actinomycetes : Types of Infectious Disease
    • Nocardia a facultative intracellular parasite that infects human macrophages and inhibits the fusion of phagosomes containing organisms with lysosomes.
    • Nocardia infections generally occur in immunocompromised patients or those with underlying pulmonary disease
  • 11. Aerobic Actinomycetes : Types of Infectious Disease
    • Nocardia asteroides complex: N . asteroides sensu stricto type VI, N . abscessus, N. farcinica , and N . nova , major cause of pulmonary infection
    • N. otitidiscavarium infrequent cause of systemic infection
    • N . brasiliensis inoculated into subcutaneous tissue of foot produces actinomycotic mycetomas
  • 12. Aerobic Actinomycetes : Types of Infectious Disease
    • Nocardial pneumonia occurs primarily in immunocompromised hosts and produces necrotizing pyogranuloma formation.
    • Extrapulmonary dissemination (~50%) and metastatic brain abscess (~30%) complications of nocardial pneumonia.
    • Actinomycotic mycetoma (pyogenic subcutaneous infection) causes local tissue destruction including bone
  • 13. Aerobic Actinomycetes : Types of Infectious Disease
    • Rhodococcus equi infects macrophages inhibiting phagolysosome fusion, and produces pulmonary disease with cavitation. Infection occurs in immunocompromised (especially HIV-infected) individuals who handle horses.
    • R. equi disseminates to other organs including the brain and subcutaneous tissue
  • 14. Aerobic Actinomycetes : Types of Infectious Disease
    • Streptomyces ( S. anulatus formerly S. griseus, and S. somaliensis ) associated with actinomycotic mycetoma in warm climates.
    • S. somaliensis a frequent cause of actinomycotic mycetomas of the head and neck.
  • 15. Aerobic Actinomycetes : Types of Infectious Disease
    • Whipple’s disease: diarrhea, weight loss, lymphadenopathy, fever, and arthralgia
    • Typical histopathology is presence of PAS-positive foamy macrophages infiltrating the lamina propria of the small intestine
    • Caused by intracellular infection of macrophages by Tropheryma whipplei (non-cultivable, diagnosis by typical histopathology combined with PCR)
  • 16. Anaerobic Actinomyces : Types of Infectious Disease
    • Actinomyces israelii causes actinomycosis in which chronic granulomas become suppurative. Cervicofacial actinomycosis most common (~60%), followed by abdominal (20%) and pulmonary (15%).
    • Tissue pus contains sulfur granules, a tangled mass of branching bacteria. Presence of sulfur granules establishes a diagnosis of actinomycosis.
  • 17.  
  • 18.  
  • 19.  
  • 20. Aerobic Actinomycetes : Identification
    • Nocardia and Rhodococcus (potentially pathogenic) and Streptomyces (less frequently pathogenic) obligate aerobes
    • Nocardia asteroides complex organisms thin (0.5-1.0  m) filaments up to 20  m in length demonstrating beaded gram-positivity
    • Rhodococcus equi gram-positive coccobacilli
  • 21. Aerobic Actinomycetes : Identification
    • Nocardia grows in a variety of media including blood and chocolate agars, Sabouraud’s dextrose agar without chloramphenicol, Lowenstein-Jensen slant, Middlebrook agar, and thioglycolate or trypticase soy broth.
    • Growth is slow requiring 5-7 days up to 3 weeks for colony formation at 25 o to 37 o C.
    • Growth in culture of Actinomadura and Streptomyces similar to Nocardia
  • 22.  
  • 23.  
  • 24.  
  • 25. Aerobic Actinomycetes : Identification
    • Nocardia and Rhodococcus are partially acid-fast positive by modified Kinyoun stain (1% H 2 SO 4 used as decolorizing agent)
    • Resistance or sensitivity of growth in glycerol broth to lysozyme
    • Urease activity
    • Decomposition of the substrates casein, tyrosine, xanthine, and hypoxanthine
  • 26.  
  • 27.  
  • 28. Aerobic Actinomycetes : Identification
    • Lysozyme 1 Urease 2
    • Nocardia asteroides + +
    • N. brasilensis + +
    • N. otitidiscavarium + +
    • Streptomyces anulatus – +/–
    • S. somaliensis – –
    • Actinomadura madura – –
    • A. pelletieri – –
    • 1 Resistance of growth in glyercol broth to lysozyme
    • 2 Christensen urea slant
  • 29. Aerobic Actinomycetes : Decomposition of Substrates
    • Cas Tyr Xan Hyp
    • Nocardia asteroides 1 – – – –
    • N. brasilensis + + – +
    • N. otitidiscavarium – – + +
    • Strepomyces anulatus + + + NR 2
    • S. somaliensis + + – +
    • Actinomadura madura 3 + + – +
    • A. pelletieri 3 + + – +
    • 1 Susceptibility testing required, N. farcinica characteristically resistant to cefotaxime, and demonstrates variable resistance to ceftriaxone.
    • 2 NR = not reported.
    • 3 A . madura esculin decomposition positive, A . pelletieri esculin decomposition negative.
  • 30. Antimicrobial Susceptibility 1 of Nocardia asteroides complex (% Susceptible)
    • Sul Cip Ami Cef Ctr Imi
    • N. asteroides 2 96-99 38-98 100 94-100 94-100 77-98
    • N. farcinica 89-100 68-88 100 0-7 0-73 64-87
    • N. nova 89-97 0 100 87-100 100 100
    • 1 Sul=sulfamethoxazole,Cip=ciprofloxacin,Ami=amikacin, Cef=cefotaxime , Ctr=ceftriaxone ,Imi=imipenem
    • 2 Nocardia asteroides sensu stricto type VI
    • Sorrell, T.C., Mitchell, D.H., and Iredell, J.R.. Chapter 252. Nocardia
    • species. In Mandell, Douglas, and Bennett’s Principles and Practice of
    • Infectious Dieseses. G.L. Mandell, J.E. Bennett, R. Dolin, Eds. Elsevier
    • Churchill Livinstone, 2005.
  • 31. Aerobic Actinomycetes : Identification
    • Rhodococcus , Gordonia, and Tsukamurella difficult to characterize biochemically with identification based on partial acid-fastness, colony morphology, and 16S rRNA gene sequence analysis
    • Rhodococcus : slimy, salmon-pink colonies
    • Gordonia : smooth, beige to salmon-pink colonies
    • Tsukamurella : cerebroid, cream colonies
  • 32. Anaerobic Actinomyces : Identification
    • Actinomyces israelii anaerobic with clinical strains varying from obligate anaerobes to microaerophilic
    • A . israelii definitively identified by detection using gas liquid chromato- graphy (GLC) of acetic and lactic acid as end products of carbohydrate metabolism
  • 33. Recommended Reading
    • Winn, W., Jr., Allen, S., Janda, W., Koneman,
    • E., Procop, G., Schreckenberger, P., Woods,
    • G.
    • Koneman’s Color Atlas and Textbook of
    • Diagnostic Microbiology , Sixth Edition,
    • Lippincott Williams & Wilkins, 2006:
    • Chapter 15. Aerobic Actinomycetes
    • Chapter 16. The Anaerobic Bacteria
  • 34. Recommended Reading
    • Murray, P., Baron, E., Jorgensen, J., Landry, M., Pfaller, M.
    • Manual of Clinical Microbiology, 9th Edition, ASM Press,
    • 2007:
    • Conville, P.S., and Witebsky, F.G. Chapter 35. Nocardia, Rhodococcus, Gordonia, Actinomadura , Streptomyces, and Other Aerobic Actinomycetes
    • Koenoenen, E., and Wade, W.G. Chapter 56. Propionibacterium, Lactobacillus, Actinomyces, and Other Non-Spore-Forming Anaerobic Gram-Positive Rods