Anaerobes Flashcards
(48 cards)
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
2
Q
What are the Anaerobic Techniques
A
- Sample should be kept anaerobic
- Culture medium should have low redox potential
- Cultures incubated under O2-Free atmosphere
3
Q
What are the Anaerobes of Veterinary Importance
A
- Minor Genera: rarely cause infections:
- Peptococs
- Peptostreptococcus
- Veilonella
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
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
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
7
Q
What are the Characteristics of Gram Negative Anaerobic Infections?
A
- Located close to a mucosal surface
- putrid odor
- Gas
- Negative aerobic culture
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
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
10
Q
What is Synergism?
A
- Mechanism:
- Supply of essential growth factors
- Protection against phagocytosis (leukotoxin)
- Creation of anaerobic conditions
11
Q
What is an example of Synergism?
A
- Trueperella pyogenes creates the environment, toxin, and substrate that complement Fusobacterium necrophorum
12
Q
What are the clinically important Gram Negative Anaerobes?
A
- Bacteroides
- Dichelobacter
- Fusobacerium
- Prevotella
- Porphyromonas
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
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
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
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
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
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
19
Q
What is F. necrophorum Mode of Infection
A
- Endogenous: Opportunistic infection (GI and respiratory)
- Exogenous: Soil
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
Necrbacillosis in Chickens
* Respiratory infctions
* Avian Diphtheria - secondary invader to fowl pox
26
Necrobacillosis in Humans
* Sore throat
* Lemierre's Syndrome
27
Necrobacillosis in Cattle
* Calf diphtheria - endogenous
* Foot rot - exogenous
* Liver abscesses - endogenous
* Metritis in Dairy cows
28
Calf Diphtheria
Necrotic Laryngitis
* 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
Foot Rot
Interdigital Necrobacillosis
* 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
Liver Abscesses
* 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
Economics of Liver Abscesses
* Loss of liver
* Animal Performance
* Reduced feed intake
* Reduced weight gain
* Reduced feed efficiency
* Reduced Carcass yield
32
*F. necrophorum* of Liver Abscesses
* Part of normal ruminal flora
* Ferment lactic acid and proteins
* Ruminal conentration increases in grain-fed cattle
33
Pathogenesis of Liver Abscesses
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
Liver Abscess Diagnosis
* Detected only after slaughter
* No clinical signs
* Nomal liver function tests
35
Liver Abscess Control
* Proper feed management
* Antimicrobial feed additives
* Chlortetracycline - \<21% reduction
* Oxytetracycline - \<55% reduction
* Tylosin - \< 75% reduction
* Vaccine:
* Bacterin (Fusogard - Elanco)
* not effective
36
FDA Guidance for Antimicrobial Use
* 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
Metritis in Dairy Cows
* 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
*Fusobacterium equinum*
* 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
*Fusobacterium gastrosuis*
* 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
Bacteroides
* 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
Enterotoxigenic *B. fragilis*
* 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
*Prevotella* and *porphyromonas*
* Gram negative
* Rods
* Anaerobic
* ***Prevotella:***
* ********Saccharolytic** (sugar fermenter)
* ***Prophyromonas:***
* **Asaccharolytic**
* Black pigmented (some)
* Normal Flora of the _oral cavity_
43
*Porphyromonas*
* 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
*Porphyromonas levii*
* Abscesses often with other bactereia (*F. necrophorum)*
* Associated with cattle F**oot Rot**
45
What are the antigen Characteristics of *Dichelobacter nodosus?*
* Fimbrial antigens: protein protective - 10 types
* A to I, and M
* O antigens: LPS
46
What contributes to the Pathogenesis of *Dichelobacter nodosus*
* 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
What is the Pathogenesis of *Dichelobacter nodosus*
1. **Entry:** skin abrasions
2. **Colonization:** mediated by pili
3. **Invasion:** Facilitated by proteases
* Synergy with *T. pyogenes and F. necrophorum*
48
What is Foot rot?
* 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
