Aerobic Actinomycetes and Anaerobic Actinomyces

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Aerobic Actinomycetes and Anaerobic Actinomyces

• Dr. John R. Warren
• Department of Pathology
• Northwestern University
• Feinberg School of Medicine
• June 2007

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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

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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 GC group

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Taxonomy of the Aerobic Actinomycetes Pathogenic
Genera

• Nocardia
• Actinomadura
• Streptomyces
• Rhodococcus
• Gordonia
• Tsukamurella
• Tropheryma whipplei (Non-cultivable)

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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 (gt3,000) widely distributed
  in soil

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Anaerobic Actinomyces Natural Habitats

• Anaerobic Actinomyces species
• are normal inhabitants of the
• mucous membranes of humans
• and animals

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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

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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

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Anaerobic Actinomyces Modes of Infection

• Actinomyces invades normally
• sterile tissue from endogenous
• mucous membrane sites of
• normal colonization

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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

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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

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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

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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

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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.

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Aerobic Actinomycetes Types of Infectious Disease

• Whipples 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)

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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.

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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

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Aerobic Actinomycetes Identification

• Nocardia grows in a variety of media including
  blood and chocolate agars, Sabourauds 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 25o to 37oC.
• Growth in culture of Actinomadura and
  Streptomyces similar to Nocardia

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Aerobic Actinomycetes Identification

• Nocardia and Rhodococcus are partially acid-fast
  positive by modified Kinyoun stain (1 H2SO4 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

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Aerobic Actinomycetes Identification

• Lysozyme1
  Urease2
• Nocardia asteroides
  
• N. brasilensis
  
• N. otitidiscavarium
  
• Streptomyces anulatus
  /
• S. somaliensis
  
• Actinomadura madura
  
• A. pelletieri
  
• 1Resistance of growth in glyercol broth to
  lysozyme
• 2Christensen urea slant

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Aerobic Actinomycetes Decomposition of Substrates

• Cas
  Tyr Xan Hyp
• Nocardia asteroides1
  
• N. brasilensis
  
• N. otitidiscavarium
  
• Strepomyces anulatus
  NR2
• S. somaliensis
  
• Actinomadura madura3
  
• A. pelletieri3
  
• 1Susceptibility testing required, N. farcinica
  characteristically resistant to cefotaxime, and
  demonstrates variable resistance to ceftriaxone.
• 2NR not reported.
• 3A. madura esculin decomposition positive, A.
  pelletieri esculin decomposition negative.

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Antimicrobial Susceptibility1 of Nocardia
asteroides complex ( Susceptible)

• Sul Cip Ami Cef Ctr Imi
• N. asteroides2 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
• 1Sulsulfamethoxazole,Cipciprofloxacin,Amiamikac
  in, Cefcefotaxime,Ctrceftriaxone,Imiimipenem
• 2Nocardia asteroides sensu stricto type VI
• Sorrell, T.C., Mitchell, D.H., and Iredell,
  J.R.. Chapter 252. Nocardia
• species. In Mandell, Douglas, and Bennetts
  Principles and Practice of
• Infectious Dieseses. G.L. Mandell, J.E. Bennett,
  R. Dolin, Eds. Elsevier
• Churchill Livinstone, 2005.

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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

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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

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Recommended Reading

• Winn, W., Jr., Allen, S., Janda, W., Koneman,
• E., Procop, G., Schreckenberger, P., Woods,
• G.
• Konemans Color Atlas and Textbook of
• Diagnostic Microbiology, Sixth Edition,
• Lippincott Williams Wilkins, 2006
• Chapter 15. Aerobic Actinomycetes
• Chapter 16. The Anaerobic Bacteria

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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