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Anonymous
ID:
47649
Filename:
Actinomyces.
Updated:
2010-11-06 07:34:53
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microbiology
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Description:
VPTH605 Exam 2
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  1. Arcanobacterium pyogenes
    • (Actinomyces pyogenes, Corynebacterium pyogenes)
    • Mucosal flora of ruminants and swine
    • Facultative anaerobe
    • Chronic purulent infections - mastitis, endometritis, pneumonia, endocarditis, arthritis, etc..
    • Opportunist, polymicrobial infections (+ anaerobes)
    • Hemolysin (pyolysin), extracellular-matrix binding proteins, proteases, can invade epithelial cells and survive in M� (how?)
    • Therapy - drainage, penicillin
    • Actinobaculum suis
    • (Actinomyces suis, Eubacterium suis, Corynebacterium suis)
    • Anaerobe
    • Necrotic purulent pyelonephritis & cystitis in swine
    • Actinomyces viscosus
    • Oral flora of dogs, humans
    • Facultative anaerobe
    • Actinomycosis in dogs and cats - chronic pyogranulomatous Infections under the skin or in body cavities (pyothorax)
    • Fimbriae
    • Microscopic diagnosis: gram stain, immunofluorescence
    • Therapy - drainage, penicillin
    • Actinomyces bovis
    • Oral flora (cattle)
    • Anaerobe
    • "Lumpy jaw" in cattle - traumatic lesions in the oral cavity leading to chronic granulomas involving bones (� actinobacillosis); fistulation through the skin or oral mucosa
    • Microscopy of sulfur granules - 10% NaOH (clubs: proteins & CaPO4), gram stain
    • Therapy - drainage, iodine solutions, penicillin
    • Nocardia asteroides
    • Ubiquitous (soil),
    • Aerobe, produce mycolic acid
    • Facultative intracellular pathogen � cell-mediated immunity
    • Chronic, granulomatous fistulous infections in the oral cavity, the subcutis and internal organs (lungs - aspiration pneumonia); mastitis (iatrogenic)
    • Virulence properties
    • Bind to and invade endothelial cells (e.g. midbrain)
    • Mycolic acid - toxic, inhibits killing by M� and neutrophils; immunostimulant, activates M� (TNF) and induces them to fuse to multinucleate cells
    • Lab diagnosis - long branching filaments, weakly gram +, � acid-fast
    • Therapy - drainage, sulfonamide-trimethoprim (penicillin-resistant)
    • Dermatophilus congolensis
    • Obligate parasite of animals
    • Aerobe
    • Parallel filaments (divides in both directions); release of zoospores (chemotactic for CO2); germ tube formation
  2. Streptothricosis (dermatophilosis) in ruminants, horses (dogs, cats, humans) - exsudative dermatitis (� rain rot� or �rain scald� in horses; "lumpy wool", "strawberry foot rot" in sheep)
    • Virulence factors - extracellular proteases (keratinase)
    • Therapy - hygiene, iodine, penicillin+streptomycin
  3. NONSPORE-FORMING ANAEROBES
    • (Quinn & Markey, Chapter 30 & 8)
    • Oral and gut flora of animals and humans
    • Infections require two simultaneous events
    • trauma of deep tissues, ischemia, � O2 tension
    • fecal contamination (anaerobes), bites
    • Polymicrobial (mixed) infections, with facultative anaerobic bacteria, synergistic process (maintenance of a low redox potential)
    • Abscesses, gingivitis, peritonitis, tissue necrosis
  4. Specimen collection and transport to the lab
    Sealed syringe filled with pus (fluid, biopsy better than swab)
  5. ACTINOMYCETES
    • (Quinn & Markey, Chapters 10-11)
    • Gram positive rods and branching filaments
    • Chronic purulent and granulomatous infections
    • Difficult to
    • treat with
    • antibiotics
    • Arcanobacterium pyogenes
    • (Actinomyces pyogenes, Corynebacterium pyogenes)
    • Mucosal (nasal and oropharyngeal) flora of ruminants and swine
    • Facultative anaerobe
    • Chronic purulent infections - mastitis, endometritis, pneumonia, endocarditis, arthritis, etc..
    • Opportunist, polymicrobial infections (+ anaerobes)
    • Hemolysin (pyolysin), extracellular-matrix binding proteins, proteases, can invade epithelial cells and survive in M� (how?)
    • Therapy - drainage, penicillin
    • Kidney - Abscessation
    • Actinobaculum suis
    • (Actinomyces suis, Eubacterium suis, Corynebacterium suis)
    • Anaerobe
    • Necrotic purulent pyelonephritis & cystitis in swine
    • Actinomyces viscosus
    • Oral flora of dogs, humans
    • Facultative anaerobe
    • Actinomycosis in dogs and cats - chronic pyogranulomatous infections under the skin or in body cavities (pyothorax)
    • Fimbriae
    • Microscopic diagnosis: gram stain, immunofluorescence
    • Therapy - drainage, penicillin
  6. Actinomyces bovis
    • Oral flora (cattle)
    • Anaerobe
    • "Lumpy jaw" in cattle - traumatic lesions in the oral cavity leading to chronic granulomas involving bones (� actinobacillosis); fistulation through the skin or oral mucosa
    • Microscopy of sulfur granules - 10% NaOH (clubs: proteins & CaPO4), gram stain
    • Therapy - drainage, iodine solutions, penicillin
  7. Nocardia asteroides
    • Ubiquitous (soil),
    • Aerobe, produce mycolic acid
    • Facultative intracellular pathogen � cell-mediated immunity
    • Chronic, granulomatous fistulous infections in the oral cavity, the subcutis and internal organs (lungs - aspiration pneumonia); mastitis (iatrogenic)
  8. Virulence properties
    • Bind to and invade endothelial cells (e.g. midbrain)
    • Mycolic acid - toxic, inhibits killing by M� and neutrophils; immunostimulant, activates M� (TNF) and induces them to fuse to multinucleate cells
    • Lab diagnosis - long branching filaments, weakly gram +, � acid-fast
    • Therapy - drainage, sulfonamide-trimethoprim (penicillin-resistant)
  9. Dermatophilus congolensis
    • Obligate parasite of animals
    • Aerobe
    • Parallel filaments (divides in both directions); release of zoospores (chemotactic for CO2); germ tube formation
  10. Streptothricosis (dermatophilosis) in ruminants, horses (dogs, cats, humans) - exsudative dermatitis (� rain rot� or �rain scald� in horses; "lumpy wool", "strawberry foot rot" in sheep)
    • Virulence factors - extracellular proteases (keratinase)
    • Therapy - hygiene, iodine, penicillin+streptomycin
  11. NONSPORE-FORMING ANAEROBES
    • (Quinn & Markey, Chapter 30 & 8)
    • Oral and gut flora of animals and humans
    • Infections require two simultaneous events
    • trauma of deep tissues, ischemia, � O2 tension
    • fecal contamination (anaerobes), bites
    • Polymicrobial (mixed) infections, with facultative anaerobic bacteria, synergistic process (maintenance of a low redox potential)
    • Abscesses, gingivitis, peritonitis, tissue necrosis
  12. Specimen collection and transport to the lab
    • Sealed syringe filled with pus (fluid, biopsy better than swab)
    • Anaerobic transport media
    • Blood culture (3x/24 hrs)
  13. Lab techniques - gram stain, gas chromatography; slow growth (O2-sensitive: thioglycolate media, anaerobic jar or glove box)
    • Therapy
    • Surgery (drainage)
    • Antibiotics
    • (resistant to
    • aminoglycosides,
    • fluoroquinolones)
  14. GRAM negative - Fusobacterium necrophorum
    Gram stain - beaded filaments
  15. Mixed infections with A. pyogenes, Bacteroides spp., etc..
    • Necrobacillosis
    • Phlegmonous and ulcerative necrotic stomatitis in cattle and swine (fights - bull nose), calf diphtheria
    • Rumenitis (grain-rich diet, rumen acidosis, ulceration), liver abscess
  16. Pericarditis (foreign body)
    • Footrot in cattle
    • Interdigital phlegmonous
    • infections (ulceration)
  17. Thrush in horses
    • Prevotella, Porphyromonas, Bacteroides
    • Leukotoxin (hemolysin)
    • LPS
    • Penicillin-susceptible, no effective vaccines
    • Hygiene - survives for months in humid bedding or soil
  18. Pr. melaninogenica, Po. asaccharolytica, B. fragilis
    Mixed with other anaerobes; oral infections, aspiration pneumonia, pyothorax (cats), castration wounds, umbilical infections, sepsis
  19. Capsule - activates complement, chemotactic for leukocytes
    • Proteases - collagenase, IgA protease
    • Nontoxic LPS
    • Some - enterotoxin, hemolysin
    • Superoxide dismutase, catalase
    • (� susceptibility to O2)
    • Therapy - metronidazole, clindamycin; antibiotic-resistance (penicillin!)
    • Dichelobacter (Bacteroides) nodosus
    • Obligate parasite of hooves of ruminants (short life in soil)
    • Contagious footrot in sheep - predisposing factors
    • (humidity, trauma)
    • Frequently with A. pyogenes, F. necrophorum, etc�
    • Fimbriae (antigenic variability: multivalent vaccines)
    • Heat-stable protease (= keratinase)
    • Penicillin-susceptible
    • Trimming of the hooves, disinfectant baths
    • Capnocytophaga canimorsus
    • Oral cavity commensal in dogs & cats
    • Bite wounds � complications (sepsis)
    • Virulence factors: sialidase, block M� killing, LPS
    • Gram positive
    • Anaerobic streptococci
    • Abscess
    • Mastitis in cows
    • Mixed with other anaerobes
    • CLOSTRIDIA
    • Spore-forming anaerobes
    • (Quinn & Markey, Chapters 14-15)
    • Large gram positive rods
    • Spores killed only by 121�C, 20 min.
    • Widely distributed
    • saprophytes -
    • soil, intestine
    • Some produce
    • potent exotoxins -
    • life-threatening
    • diseases
    • Clostridium tetani
    • Widespread - intestines of animals and humans, soil
    • Tetanus - human and horses are most susceptible, pigs, ruminants, (dogs)
    • Wound infections (castration, umbilicus), anaerobic conditions for spore germination, exotoxin production
  20. Neurotoxin (tetanospasmin)
    • Highly toxic protein
    • Binds to peripheral nerves near wound (irreversible binding to gangliosides of nerve cells),
    • Transmitted to cranial nerve nuclei
    • Protease activity on specific vesicle-associated membrane proteins
    • Blocks release of inhibitory transmitters (e.g.GABA)
  21. Spastic paralysis (protrusion of the nictitating membrane, sawhorse stance; in humans, "sardonic smile", lockjaw - trismus); death by respiratory failure
    • Hemolysin (tetanolysin)
    • Toxoid vaccine
    • Sedation; surgical debridement, penicillin (antitoxin - frequently too late)
  22. Clostridium botulinum
    • Habitat - soil and marine sediment
    • Food contamination by spores (meat, vegetables, fish)
    • Botulism
    • Intoxication by exotoxins previously produced in food, after germination of spores under anaerobic conditions, e.g. spoiled silage, rotting vegetables or carcasses, contaminated cans
  23. Wound botulism
    • Infant botulism; shaker foal syndrome
    • Neurotoxins (8 serotypes)
    • Most potent known toxins!
    • Heat-labile proteins, resistant to enteric proteases
    • Bind to gangliosides at motor-neuromuscular junctions
    • Protease activity on specific vesicle-associated membrane proteins
    • Block the release of the neurotransmitter acetyl-choline, inhibition at peripheral cholinergic synapses
  24. Cattle, horses & birds are highly susceptible (� carnivores and swine)
    • Suspicious food - 100�C, 10 min inactivates the toxin
    • Toxoid vaccines for cattle
    • Therapy - ASAP tracheotomy and antitoxin
  25. Histotoxic Clostridia
    • Clostridium perfringens (welchii)
    • Types A to E - � 2 major lethal toxins (out of 4)
    • Gas gangrene - Type A (most widespread)
  26. Ruminants,
    • horses,
    • humans
    • (wartime)
  27. Deep wound infections
    • Anaerobic conditions
    • 2 hemolysins responsible for leukostasis, vascular dysfunction and capillary leak leading to necrosis and gas formation in muscles (gangrene), toxemia
    • a toxin, lecithinase, phospholipase C
    • q (theta) toxin, perfringolysin
    • Collagenase (pulpy muscles)
    • Mixed infections with other Clostridia
    • Surgical and antibiotic treatments
  28. Food poisoning (type A) in man (meat)
    • Enterotoxemia
    • Type C - b toxin (protease sensitive), hemorrhagic enteritis in neonatal farm animals
    • Type D - e toxin (prototoxin, activated by enteric proteases - necrosis, lethal, plasmid-encoded), "Pulpy kidney" disease of sheep and goats (sudden change to a rich diet); brain edema
    • Vaccines (appropriate toxoid), hyperimmune sera (colostrum)
    • Clostridium chauvoei (C. feseri)
    • More prevalent in certain geographic areas
    • Blackleg - ruminants
    • Entry through the gut (bacteremia), wounds; germination and multiplication in traumatized muscle tissue; typical lesions rarely found (bubbles, rancid odor)
    • Exotoxins - hemolysins, a necrotoxin, etc..
    • Diagnostic - immunofluorescence
    • Vaccine (formalin-treated cultures)
  29. Clostridium septicum
    • Worldwide (unlike C. chauvoei)
    • Malignant edema: ruminants, horses, pigs
    • pathogenesis due to exotoxins, similar to C. chauvoei
    • Entry through wounds; cellulitis with � localized large swelling of muscle tissue
    • Diagnostic - immunofluorescence
    • Vaccine
  30. Clostridium novyi (= C. oedematiens)
    • Various types produce different toxins (different diseases)
    • Gas gangrene (Type A) - sheep, cattle, human
    • Extensive edema (rams - "big head")
    • Mixed infections with other Clostridia
    • Necrotizing infections among injecting-drug users (with other Clostridium sp.)
  31. Infectious necrotic hepatitis (Type B) or "Black disease�- sheep, cattle (horse)
    • Liver flukes infections cause anaerobic conditions for the germination of spores in the liver
    • Exotoxins (4)
    • a toxin - gaps between endothelial cells
    • b toxin - phospholipase C (hemolysin) release of hemolyzed blood in tissues (blackening) � hypovolemic shock, tissue necrosis, lethal toxemia
    • Elimination of the snail (flukes); vaccines
    • Clostridium haemolyticum (C. novyi, type D)
    • Bacillary hemoglobinuria ("red water") - cattle and sheep
    • Pathogenesis: similar to "Black disease" (liver flukes)
    • Exotoxins - phospholipase C (b toxin), intravascular hemolysis, lethal anoxia
    • Histotoxic Clostridia
    • Clostridium difficile
    • Pseudomembranous colitis
    • Humans, horses (dogs)
    • Associated with previous antibiotic (cephalosporins, penicillins, clindamycin) treatment - suppression of the normal anaerobic flora. Unharmed spores can germinate.
    • Toxins A and B (cytotoxic - modify small GTPases, actin disassembly) - diarrhea