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Bacteriology and Mycology > Anaerobes > Flashcards

Anaerobes Flashcards

1
Q

What are Anaerobes?

A
  • Bacteria that grow in the absence of oxygen
  • Characteristics:
    • Generate ATP without O2
    • Varying degree of sensitivity to O2
      • Aerotolerant
      • Obligate
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2
Q

What are the Anaerobic Techniques

A
  1. Sample should be kept anaerobic
  2. Culture medium should have low redox potential
  3. Cultures incubated under O2-Free atmosphere
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3
Q

What are the Anaerobes of Veterinary Importance

A
  • Minor Genera: rarely cause infections:
    • Peptococs
    • Peptostreptococcus
    • Veilonella
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4
Q

What are the Specific Infections of Anaerobic Bacteria?

A
  • Dichelobacter nodosus -* foot rot sheep
  • Fusobacterium necrophorum -* calf diphtheria, foot rot and liver abscesses cattle
  • Brachyspira hyodysenteriae -* swine dysentery
  • Actinobaculum suis -* UTI sows
  • Clostridium sp. -* pseudomembranous colitis in humans, Enterocolitis in animals
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5
Q

What are the nonspecific infections of Anaerobes?

A
  • Abscesses
  • Dental and oral infections
  • Chronic infections in thoracic and peritoneal cavities
  • Infections of the female genital tract
  • Bite wounds
  • Cellulitis
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6
Q

What are Gram Negative Anaerobes?

A
  • Most common anaerobic infections
  • Part of the normal flora - opportunistic
  • Generally abscesses (suppurative) and necrotic infections
  • Often involve mucous membranes
  • Polymicrobial infections
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7
Q

What are the Characteristics of Gram Negative Anaerobic Infections?

A
  • Located close to a mucosal surface
  • putrid odor
  • Gas
  • Negative aerobic culture
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8
Q

What are the Virulence Factors of Gram Negative Anaerobes that create anaerobic microenvironment?

A
  • Require creation of anaerobic microenvironment
    • LPS
    • Hemolysin
    • Platelet aggregation factor
    • Synergy with facultative bacteria
    • Superoxide dismutase
    • Catalase
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9
Q

What are the other Virulence Factors of Gram Negative Anaerobes

A
  • Complex not well characterized
  • Structures: Capsule, Pili, LPS, adhesins, etc
  • Exotoxins: Enterotoxin, Hemolysin, leukotoxin, etc
  • Enzymes: Neuraminidase, DNases, Proteases, Ureases, etc.
  • Fermentation products: Acids, Ammonia
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10
Q

What is Synergism?

A
  • Mechanism:
    1. Supply of essential growth factors
    2. Protection against phagocytosis (leukotoxin)
    3. Creation of anaerobic conditions
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11
Q

What is an example of Synergism?

A
  • Trueperella pyogenes creates the environment, toxin, and substrate that complement Fusobacterium necrophorum
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12
Q

What are the clinically important Gram Negative Anaerobes?

A
  • Bacteroides
  • Dichelobacter
  • Fusobacerium
  • Prevotella
  • Porphyromonas
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13
Q

What is Dichelobacter nodosus?

A
  • Gram Negative
  • Rods - dumb-bell shaped
  • Heavily Fimbriated
  • Causes Foot rot in sheep
  • Habitat:
    • Obligate pathogen of the epidermal tissues of the hoof of sheep goats, and cattle
    • Can only survive for a few days in soil
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14
Q

What is the treatment for Foot Rot?

A
  • Trimming affected hoof - remove necrotic tisses
  • Topical applications of antiseptics or antibiotics
  • Foot baths:
    • 5% formlin, 5% coppersulfate, or 10% zinc sulfate
  • Antibiotics:
    • Penicillin + Aminoglycoside; Tetracyclines, Fluoroquinolones, Macrolides
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15
Q

Is there a Foot Rot Vaccination?

A
  • Bacterins or fimbriae-based vaccine
  • Recombinant fimbriae
    • Multistrain
  • Vaccination is part of the eradication program in Australia and New Zealand
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16
Q

What is Fusobacterium

A
  • Gram Negative
  • Spindle Shaped
  • Non-spore forming
  • Anaerobe
  • 17 species
    • F. nuclatum: Human
    • F. necrophorum: Animal and Human
    • F. equinum: Horses
    • F. gstrosuis: Gastric ulceration in swine
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17
Q

What is ​Fusobacterium necrophorum

A
  • Gram Negative
  • Anaerobic
  • Rod shaped - pleomorphic
  • Associated with nectoric lesions in animals and humans
  • “Necrobacillosis”
  • Normal inhabitant of the GI, respiratory, urinary, and genital tracts
  • Inhabitates soil
  • 2 biotypes/subspecies:
    • necrophorum
    • funduliforme
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18
Q

Fusobacterium necrophorum Subspecies Infections

A
  • Beef cattle:
    • Hepatic necrobacillosis
    • necrophorum and/or funduliforme
  • Beef and Dairy Cattle:
    • Interdigital necrobacillosis (Foot Rot)
    • necrophorum and/or funduliforme
  • Calves:
    • Necrotic laryngitis (Calf diphtheria)
    • necrophorum and/or funduliforme
  • Horses
    • Thrush
    • ND
  • Antelopes:
    • Mandibular abscesses, Respiratory infections
    • necrophorum and/or funduliforme
  • Humans:
    • Pharyngitis, Pharyngotonsilitis, Peritonsillar abscesses, Lemierre’s syndrome, soft tssue abscess
    • funduliforme
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19
Q

What is F. necrophorum Mode of Infection

A
  • Endogenous: Opportunistic infection (GI and respiratory)
  • Exogenous: Soil
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20
Q

F. necrophorum Virulence Factors

A
  • Leukotoxin:
    • ​cytotoxic to neutrophils, macrophages, hepatocytes, and ruminal epithelial ccells
    • Protects agains phagocytosis (neutrophils, kupffer cells) Damages hepatic parenchyma by the release of cytolytic products
  • LPS:
    • ​Necrotic effect and induces disseminatd intravascular coagulation
    • Creates anaerobic micro environment conducive for anaerobic growth
  • Hemolysin
  • Hemagglutinin
  • Adhesins
  • Dermonecroic toxin
  • Platelet aggregation factor
  • Proteases
21
Q

Necrobacillosis

A
  • Suppurative and necrotic
  • Low mortalilty
  • High morbidity
  • Affects animal productivity
22
Q

Necrobacillosis in Horses

A
  • Trush
  • Necrotic dermatitis
  • Pneumonia
  • Septicemia
23
Q

Necrobacillosis in Sheep

A
  • Lip and leg ulceration
  • Infectious blbar necrosis
  • Foot rot
24
Q

Necrobacillosis in Swine

A
  • Ulcerative stomatities
  • Ncrotic rhinitis
  • Necrotic enteritis
  • Secondary invader in Swine dysentery
25
Q

Necrbacillosis in Chickens

A
  • Respiratory infctions
    • Avian Diphtheria - secondary invader to fowl pox
26
Q

Necrobacillosis in Humans

A
  • Sore throat
  • Lemierre’s Syndrome
27
Q

Necrobacillosis in Cattle

A
  • Calf diphtheria - endogenous
  • Foot rot - exogenous
  • Liver abscesses - endogenous
  • Metritis in Dairy cows
28
Q

Calf Diphtheria

Necrotic Laryngitis

A
  • Calves up to 3 years old
  • Predisposing factor:
    • breach in mucus membrane
  • Acute or chronic
  • Clinical signs:
    • Fever, dyspnea, hard breathers, cough, loss of body weight
  • Lesions:
    • necrosis of mucus membrane, larynx, and adjacent tissues
  • Treatment:
    • Penicillin, tetracyclines, tylosin
29
Q

Foot Rot

Interdigital Necrobacillosis

A
  • Major cause of lameness in feedlot and dairy cattle
  • Predisposing factor:
    • Injury, damp soil, overgrown hoof
  • Causes: alone or mixed
    • Porphyromonas levii
    • Dichelobacter nodosus
    • Trueperella pyogenes
  • Acute or chronic necrotizing infection of the foot
  • Clinical signs:
    • Cellulitis, swelling between digits, exudate and pus
  • Treatment:
    • Systemic administration of tetracyclines
30
Q

Liver Abscesses

A
  • Incidence: 20-30%
  • # 1 cause of liver condemnation in the US
  • Bacterial Flora:
    • Fusobacterium necrophorum - 100%
    • ssp. necrophorum - 75%
    • ssp. funduliforme - 40%
    • Trueperella pyogenes -25%
    • Salmonella enterica -24%
31
Q

Economics of Liver Abscesses

A
  • Loss of liver
  • Animal Performance
    • Reduced feed intake
    • Reduced weight gain
    • Reduced feed efficiency
  • Reduced Carcass yield
32
Q

F. necrophorum of Liver Abscesses

A
  • Part of normal ruminal flora
  • Ferment lactic acid and proteins
  • Ruminal conentration increases in grain-fed cattle
33
Q

Pathogenesis of Liver Abscesses

A
  1. High grain feeding
  2. Ruminal Acidosis
  3. Rumenitis
  4. bacteria cause ruminal abscesses
  5. bacterial emboli travel through the portal vein
  6. invade the Liver and grow
34
Q

Liver Abscess Diagnosis

A
  • Detected only after slaughter
  • No clinical signs
  • Nomal liver function tests
35
Q

Liver Abscess Control

A
  • Proper feed management
  • Antimicrobial feed additives
    • Chlortetracycline - <21% reduction
    • Oxytetracycline - <55% reduction
    • Tylosin - < 75% reduction
  • Vaccine:
    • Bacterin (Fusogard - Elanco)
      • not effective
36
Q

FDA Guidance for Antimicrobial Use

A
  • Judicious use of medically important antimicrobial drugs in food producing animals
    • limiting use to assure animl health
    • limiting use under veterinary oversight
  • Tylosin:
    • ​Not for growth promotion, but to prevent infection
    • Need VFD
37
Q

Metritis in Dairy Cows

A
  • Inflammatory disease of dairy cows
  • First 2 weeks post-partum
  • Incidence: 10-20%
  • Signs:
    • Fetid uterine discharge, Fever, decresed milk production
  • Uterine dysbiosis:
    • F. necrophorum
    • T. pyogenes
    • E. coli
38
Q

Fusobacterium equinum

A
  • Similar to F. necrophorum
    • PCR to distinguish
  • Normal flora of the GI, respiratory and genitourinary tracts
  • Opportunistic pathogen
  • Abscesses and necrotic infections, particularly oral, paraoral, and lower respiratory tract
  • Leukotoxin may be the virulence factor
39
Q

Fusobacterium gastrosuis

A
  • Normally present in the oral cavity, tonsils, and upper non-glandular region of the stomach of pigs
  • Contributes to the pathogenesis of gastric ulceration, polymicrobial infection, mainly initiated by Helicobacter suis
  • Common disease of pigs, may result in decreased feed intake, body weight gain and even death.
40
Q

Bacteroides

A
  • Gram negative
  • Rods
  • Anaerobic
  • Bacteroides fragilis
    • ​Normal flora of the colon of humans and animals
    • Causes Abscesses and soft tissue infections
    • Capsular polysaccharides is a major virulence factor
41
Q

Enterotoxigenic B. fragilis

A
  • Produce enterotoxin ‘fragilysin’
    • Small protein (20kDa) - A zinc protease
    • stimulates fluid secretion
    • Causes enteritis in calves piglets, foals, infant rabbits, and children
  • Intrabdominal abscesses
42
Q

Prevotella and porphyromonas

A
  • Gram negative
  • Rods
  • Anaerobic
  • Prevotella:
    • ​Saccharolytic (sugar fermenter)
  • Prophyromonas:
    • Asaccharolytic
  • Black pigmented (some)
  • Normal Flora of the oral cavity
43
Q

Porphyromonas

A
  • 13 species - 9 from animals
    • P. gingivalis most common human pathogen
    • P. gulae most common animal pathogen
  • Periodontal infections: gingivitis, periodontitis, periodontal abscesses
  • Found in dog and cat bite wounds
44
Q

Porphyromonas levii

A
  • Abscesses often with other bactereia (F. necrophorum)
  • Associated with cattle Foot Rot
45
Q

What are the antigen Characteristics of Dichelobacter nodosus?

A
  • Fimbrial antigens: protein protective - 10 types
    • A to I, and M
  • O antigens: LPS
46
Q

What contributes to the Pathogenesis of Dichelobacter nodosus

A
  • Mode of infection: Infected animal is source
  • Predisposing factors: Skin abrasion, wounds, larval damage, damp pasture
  • Virulence factors:
    • Fimbriae: adhesion
    • Proteases: tissue destruction
    • Endotoxin: inflammation
47
Q

What is the Pathogenesis of Dichelobacter nodosus

A
  1. Entry: skin abrasions
  2. Colonization: mediated by pili
  3. Invasion: Facilitated by proteases
    • Synergy with T. pyogenes and F. necrophorum
48
Q

What is Foot rot?

A
  • Infection of the epidermal tissues of the feet
  • 3 forms: Virulent, intermediate, Benign
  • Lameness and loss of Body weight
  • Affects sheep
    • goats and cattle rare
  • Seasonal occurrence

Bacteriology and Mycology (35 decks)

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