Exam 2 Flashcards
1
Q
What is the most common c/s of listeriosis?
Circling disease
What pathogen is the cause of circling disease?
A
Localized ascending asymmetric infection of the brain stem of ruminants
-Listeria monocytogenes
2
Q
What nerves are damaged?
A
Cranial nerves V, VII, and VIII.
C/S:
-Unilateral facial paralysis
-Meningoencephalitis
Tx:
-High dosages of antimicrobials effective if early
3
Q
What are the characteristics of listeria monocytogenes?
Monocytogenes Most pathogenic
A
- Small rod
- hemolytic colonies in blood agar
- Gram positive
- Non-spore forming
- Grows on non-enriched media
- Facultative anaerobe
- Catalase-positive
- Oxidase negative
- Hydrolyses esculin
- Environmental saprophytes (GI of carrier, oral-fecal route)
- *Outbreaks = bad silage**
Tolerates
- 4 to 45 Celsius
- pH 5.5 to 9.6
4
Q
What disease or C/S does Listeria ivanovii cause?
What animals are affected?
A
- Less pathogenic than Monocytogenes
- Sheep cattle
- Causes abortion
5
Q
What disease or C/S does Listeria innocua cause?
What animals are affected?
A
- Meningoencephalitis
- Sheep
6
Q
What are the three major forms of listeriosis in ruminants?
How long is the incubation period?
What are the lesions and clinical signs?
A
- Neural: circling disease, silage disease, meningoencephalitis
- Visceral: septicemia, seen in neonates, specially calves and piglets
- Abortions: sporadic abortions
Incubation: 14- 40 days
Lesions:
- Neural: micro abscesses and perivascular lymphocytic cuffing
- Depression, drooping ears, protrusion of the tongue, salivation, paralysis of the face.
- Death within days
Clinical signs
- Abortion no signs for 12 days
- Septicemic: 2-3 days incubation, micro abscesses of the heart, kidney, liver
- Cattle and sheep: keratoconjunctivitis and iritis (ocular listeriosis)
7
Q
Pathogenesis of Listeriosis
Transmission
A
- Ingestion of contaminated silage
- Organisms penetrate M cells in Peyer’s patches in the intestine
- Lymph and blood spread
- Pregnancy = transmission transplacental
- Mucosal invasion through the dental pulp, followed by trigeminal nerve infection with axonal transport to the brain, midbrain, pons and medulla oblongata.
Transmission
- Temperate or colder climates high incidence of intestinal carriers worldwide
- Natural reservoir = soil and mammalian GI tract (monocytogenes) which contaminate vegetation
- Animal to animal via fecal-oral route
- Primary winter-spring feedlot animals
- less acidic pH of spoiled silage = pathogen multiplication
- Remove or change Silage
8
Q
Virulence factors
Diagnosis
Treatment
Control
A
- Invades epithelial cells or phagocytic cells
- Listeriolysin = hemolysin breaks down phagosome membrane. Once in cytoplasm, it begins replication
- Actin tails = spread intracellular
Dx
- Clinical signs, spoiled feed
- Lab specimens: CSF, cotyledon (abortion), fetal abomasal contents, uterine discharges.
Pathogen test
- Small colonies, smooth, flat, BLUE-GREEN color when illuminated obliquely
- Narrow zone of complete hemolysis
- CAMP test positive
- Catalase positive
- Tumbling motility at 25 C
Tx and control
- Penicillin
- Ceftiofur
- Erythromycin
- Trimethoprim/sulfonamide
- High doses required
Outbreak
- animals segregation
- corn ensiled before too mature = acidic pH
Zoonotic Potential
- Raw milk
- Fetal material handling
- Raw vegetables
9
Q
Tetanus and Botulism
A
- Both affect the nervous system
- Both are caused by genus Clostridium
10
Q
What are the characteristic c/s of Tetanus?
A
-CNS: spasmodic, tonic muscular contractions
11
Q
What are the characteristic c/s of Botulism?
A
-Neuromuscular junction, flaccid paralysis
12
Q
Clostridium spp.
A
- Gram-positive
- Obligate anaerobe
- Spore-forming rods
- Found in soil and GI of some animals
- Produce potent exotoxins
13
Q
How is C. tetani introduced into body?
Tx, Dx, c/s
A
- Deep puncture wounds: dehorning, traumatic wound, castration in cattle.
- Toxin causes generalized muscular spastic paralysis
Tx
- Supportive care
- Injection of antitoxin
- Tetanus toxoid vaccine
C. tetani
- Lacks oxidase, superoxidase, dismutase
- Susceptible to oxygen
- Drum-stick appearance rod
- Tissue necrosis due to soil or foreign object contributes to multiplication
- Other bacteria that take up the oxygen contributor
Spread of Tetanus toxin
- Tetanospasmin: causes spasmodic, tonic contractions by interfering with release of inhibitory neurotransmitter from presynaptic nerve ending
- Descending tetanus when toxin excess is carried by lymph to bloodstream arriving at CNS
- Can be severe = bone fractures
- Respiratory failure, cardiac arrhythmias, tachycardia, hypertension
C/S or findings
- Lockjaw
- sawhorse stance
- Profuse sweating in horses, saliva accumulation
- Sensitivity to touch
- Respiratory failure may occur
Dx
- Clinical signs, history of trauma
- Tetanus toxin in serum
- Gram stain smears
- Anaerobic culture
- PCR on wound material
Tx
- Antitoxin: specific antibody to a toxin
- Toxoid: vaccine
- Large doses of penicillin; metronidazole
- Quiet and dark environment
- IV therapy sedatives, tranquilizers
- Surgical debridement of wound
14
Q
What animals are most and less susceptible to C. tetani?
A
- Most susceptible: horses
- Least susceptible: birds
- Humans after horses, dogs less
15
Q
Clostridium botulinum
A
Characteristics
- Gram-positive rod
- Forms spores
- Saprophyte in soil and transient in feces
- Obligate anaerobe
- Botulinum toxin potent
- Susceptibility (most to least): Water birds, poultry, horses, human, cattle, dogs, cats, pig.
- 8 different strains: B = horses, A, E = humans, C alpha = Waterfowl, C beta = Cattle, horses, humans, D = cattle, sheep.
Entry
- Exotoxin mediated, not bacteria itself
- Different than tetanus (bacteria enters and produces toxin)
- Toxin is sufficient to cause disease
- Toxins can enter via:
1. INGESTION of PREFORMED TOXIN via contaminated food - Example: feed contaminated with animal carcasses or bird droppings
2. TOXICOINFECTIONS (less common) bacteria multiply in intestinal tract, possibly ulcers, produce toxin which is absorbed systematically - Floppy baby syndrome
- Shaker foal syndrome (wound botulism)
3. Wound botulism: (rare) toxin absorbed through wound, multiplying in wound
Multiplication and spread
-following entry, toxin is distributed via bloodstream to neuromuscular junction. Multiplication doesn’t always apply because the toxin is all that is needed to cause disease.
16
Q
Tetanus vs botulin toxin
A
- In botulism toxin prevents synaptic release of acetylcholine at the neurotransmitter junction at peripheral nerve endings, leading to muscular blockage and flaccid paralysis.
- Tetanus toxin inhibits inhibitory transmitter in CNS which leads to continuous stimulation
17
Q
Botulism Tx and prevention
A
- Antitoxin: type specific or combined. Only inactivates toxin not yet bound. Amount needed depends on how much was absorbed
- Antibiotics: not always applicable bc no bacteria present; however, helps to prevent secondary bacterial infection
- Supportive care
- Prognosis: grave, recovery may take weeks to months
- Immunization with toxoid. Cattle (C+D) horse (B).
- Toxin typing necessary
* *Most potent toxins: 1 g kill 10 million people or 400,000 cows
18
Q
Glasser’s disease
What animals are affected?
What pathogen causes it?
A
- It affects pigs
- Haemophilus parasuis
19
Q
Characteristics of Haemophilus parasuis
A
- Gram-negative rods
- Small motile
- Fastidious: some species require X and V factors in chocolate agar to grow
- 5-10% oxygen optimal growth
- Facultative anaerobes
- Commensals on mucous membranes
20
Q
What pathogen causes thrombotic meningoencephalitis (TME) in cattle?
A
Histophilus somni and it causes septicemia
21
Q
Histophilus somni
Haemophilus parasuis
Avibacterium paragallinarum
A
- Coccobacillary and may form short filaments
- Do not grow in MacConkey Agar
- Fastidious growth: specific and picky
- Transparent, dewdrop-like colonies
- H. parasuis (Catalase +, Oxidase -) and Avibacterium paragallinarum require Factor V (NAD)
- H. somni does not require factor X and V. Catalase negative, and oxidase positive.
22
Q
Pathogenicity and pathogenesis
Histophilus somni
Haemophilus parasuis
A
- Opportunistic due to predisposing factors
- Young or naive
- environment and other factors contribute
23
Q
Virulence factors Histophilus somni
A
- endotoxin
- Phase variation Lipo-oligosaccharide and evasion of immune response
- LOS apoptosis of endothelial cells and leukocytes
- Production of transferrin and immunoglobulin-binding proteins
- Immunoglobulin-binding proteins Fc portion of IgG2 resistance to complement mediated killing in serum
- Biofilm formation = exopolysaccharide and filamentous haemagglutinin proteins
Dx
- Specimen need to be frozen in dry ice to lab within 24 hours
- Chocolate agar or blood agar inoculated with a streak of S. aureus. 5-10% CO2, 37C for 2-3 days in moist atmosphere
Identification criteria
- Small, dewdrop-like colonies after 1-2 days
- Requirement V and X growth factor
- Biochemical profile
- PCR
24
Q
Infections Histophilus somni in cattle
A
- Part of normal flora in male and female genital tracts. It can also colonize the respiratory tract
- Environmental Stress contributor
- Direct contact or aerosol
- More resistant in the environment than Haemophilus spp.
C/S
- Septicemia
- TME: thrombotic meningoencephalitis young cattle recently introduced to feedlots
- High fever, depression, blindness, ataxia, lameness.
- Sudden death due to myocarditis
- Arthritis after acute phase survival
- H. somni isolated from enzootic calf pneumonia complex
Dx
- Neurological signs
- Multiple foci of hemorrhagic necrosis affected brains at post-mortem
- Histologically: vasculitis, thrombosis, and hemorrhage in brain, heart and other parenchymatous organs
- Confirmation by isolation and identification from CSF
Tx
- Isolation
- Oxytetracycline
- Penicillin, erythromycin, potentiated sulfonamides
- Bacterins may reduce morbidity and mortality
25
Infections Histophilus somni in Sheep
- Ovine strains carried by healthy sheep in prepuce or vagina
- H. somni causes epididymitis in young rams
- Vulvitis, mastitis, and reduced reproductive performance in ewes.
- H. somni may also cause: Septicemia, arthritis, meningitis, pneumonia in lambs
26
Glasser's Disease
| What causes it, what animals are affected?
- Haemophilus parasuis
- Pigs up to 12 weeks of age
- Polyserositis and leptomeningitis
- Direct contact or aerosols from sows shortly after birth
- Part of the normal flora of upper respiratory tract
- Stressful environmental conditions contributor
- Active immunity after 7-8 wks of age
C/S
- Incubation period 1-5 days
- Anorexia
- Pyrexia
- Lameness
- Recumbency
- Convulsions
- Cyanosis and thickening of the pinna
- Pigs may die suddenly without signs
Dx
- Isolation and identification from joint fluid, heart blood, CSF, post-mortem tissues of a recently dead pig are confirmatory
- Post-mortem findings include polyserositis and meningitis
Tx
- antimicrobial drugs as tetracycline, penicillin, sulfonamides EARLY effective
- Stress factors should be eliminated
- Bactrins may stimulate protective immunity
27
Cryptococcosis
What organism causes it?
what are its characteristics?
- Cryptococcus neoformans
- Capsulated yeast, NOT dimorphic FUNGI
- Common in cats and dogs, less in large animals
- Reservoir: soil especially associated with pigeon excrement
- Not considered contagious
- Acquired from environment
Cats
- sneezing, labored breathing
- Nasa discharge
- Hard, nodular skin swellings, most often over the bridge of the nose
- Distortion of the nasal cavity
- Neurological abnormalities (seizures, incoordination, behavioral changes.
- eyes disorders (inflammation of the choroid and retina)
Dogs
- Disseminated form more common with CNS
- Cryptococcus remains in yeast form inside and outside the host
- Inhalation of unencapsulated yeast cells in environment
- Capsulated yeast in vivo
- Nasal mucosa is the site of infection primarily
Dx
- Clinical sigs
1. Impression smears of exudate or granulomatous tissue
- KOH preparations
- India Ink preparations on CSF or clear exudates
2. Culture
- Biopsy, CFS, exudate
- easily cultured, capsulated yeast grows at 37C
Tx
- surgical intervention, cryotherapy
- Antifungals: azoles derivatives
Low Zoonotic potential
28
Contagious Equine Metritis and Brucellosis
Key points
- Taylorella equigenitalis causes (CEM)
- Taylorella equigenitalis and T. asinigenitalis are the only members of the genus
- Short, non-motile
- Gram negative rods
- Microaerophilic, factor X stimulates growth
- Fastidious, chocolate agar
- Positive oxidase, catalase, and phosphatase tests
- CO2 5-10% for growth
- Taylorella spp. do not grow in MacConkey agar
Habitat
- Genitals of stallions, mares and foals
- T. equigenitalis is harbored in the urethral fossa of stallions and clitoral fossa of infected mares
- T. asinigenitalis can be isolated from the genital tract of donkeys
C/S
- T. equigenitalis: contagious equine metritis
- T. asinigenitalis: no clinical disease in donkeys. Grows slower than T. equigenitalis, reacts weakly in indirect fluorescent antibody test with T. equigenitalis-specific antibody, different in DNA-DNA hybridization assays
CEM
- Highly contagious
- Venereal disease localized
- Mucopurulent vaginal discharge
- Temporary infertility
- Economically important thoroughbred farming
- Reservoir: infected stallions and mares
- Stallions: no signs of illness
- Transmission: during coitus, contaminated instruments, foals infected at birth.
- Bacterium must be deposited in uterus for infection to occur - non spontaneous ascending infection
29
CEM pathogenesis, C/S, Dx, Tx
- Introduction to the uterus
- T. equigenitalis induces acute endometritis
- Initially mononuclear cells and plasma cell infiltrate
- Neutrophils arrive later and result in profuse mucopurulent exudate
C/S
- T. equigenitalis = acute endometritis subsides within a few days
- Most mares copious mucopurulent discharge without systematic disturbance
- Infertile for a few weeks
- Recover without treatment
- 25% remain carriers
- Infection does not induce protective immunity
Dx
-C/S, discharge 2-7 days mares
-Bacteriological culture
-suitable media
-Chocolate agar: with amphotericin B, crystal violet and strptomycin
- CEM Timoney agar: Eugon with trimethoprim and clindamycin
-Swabs:
Mares: clitoral fossa sinuses endometrium
-Foals: clitoral of fillies and penile sheath tip of penis in colts
-Stallions: urethra, penile sheath, preejaculatory fluid
-Swabs should be transported in Amies charcoal transport medium
-Plates 37C, 5-10% CO2, for 4-7 days
- Colonies small, smooth, yellowish grey entire edge
- Positive catalase, oxidase and phosphatase tests
- side agglutination using high titer
- Fluorescent antibody may be used
- Latex agglutination test
- PCR
- Serological tests
- Pulse-field gel electrophoresis
Tx
- Eliminate carrier stage by washing external genitalia daily with 2% chlorohexidine and nitrofurazone ointment
- Daily uterine infusions of penicillin for mares
* **CEM is notifiable****
- If present breeding services should cease
- Quarantine of new additions
- pre-import and pre-export testing for the pathogen
30
Brucellosis
| Brucella spp.
- Small
- Gram Negative
- coccobacilli
- Non-motile
- Catalase positive
- Aerobic and capnophilic
- Stain red using Modified Ziehl-Neelsen (MZN) stain
- Most Oxidase positive
- Urease-positive except B. bovis
- Intracellular pathogen
- Target repro organs
- Some cause undulant fever in humans
Usual habitat
- Predilection for male and female repro organs in sexually mature animals
- Each brucella spp infect a particular animal species
- Infected animals serve as reservoir; often indefinitely
- Organisms shed by infected animals remain viable in moist environment for months
- direct contact or fluids and tissues associated with abortions
31
Brucella spp. characteristics
- Small
- Gram Negative
- coccobacilli
- Non-motile
- Catalase positive
- Aerobic and capnophilic
- Stain red using Modified Ziehl-Neelsen (MZN) stain
- Most Oxidase positive
- Urease-positive except B. bovis
- Intracellular pathogen
- Target repro organs
- Some cause undulant fever in humans
- smooth, small, glistening, bluish colonies for B. abortus, B. melitensism B suis.
- Rough dull yellowish and friable for B. ovis and B. canis.
Dx
- Biochemical tests
- Agglutination tests
- Specific culture tests requirements for growth. Inhibited by some dyes
- Susceptible by phages- Tibilisi phage
- Molecular methods: PCR, PCR-RFLP, PFG
B. ovis
- 1 biotype
- Requires CO2
- Negative production of H2S (hydrogen sulfide or Hydrosulfuric acid)
- Negative urase activity
- Positive growth Thionin
- Negative growth Basic fuchsin
32
Pathogenesis, Dx
- Outcome depends on:
- number of infecting organisms
- virulence of infecting strain
- Host susceptibility, age
Brucella that lacks LPS produce rough colonies, which are less virulent
Erythritol, a polyhydric alcohol in placental acts as growth factor
Intracellular replication also occurs in trophoblasts cells.
Chronic brucellosis bacteria localizes also in joints and intervertebral discs
Brucella containing vacuole with rough endoplasmic reticulum, replication through fusion
- Brucella can replicate within phagocytic and other cells, which contributes to disease progression
- Macrophages kill most but some survive and replicate within macrophages
- The O-chain of Brucella LPS necessary for prevention of lysosome fusion and entry promotion
- Manipulates vesicle trafficking leading to vacuole that fuses to the ER and facilitates intracellular replication.
Dx
- Careful with suspected specimens
- Serological tests: milk ring test, Rose-Bengal plate test, Complement Fixation test, indirect ELISA, cELISA, Serum agglutination, antiglobulin test.
- Isolation and identification (culture)
- Selective medium is used, incubated microaerophilically at 37C
- MZN positive
- PCR test
33
Bovine Brucellosis
- Cause by Brucella abortus
- Eradicated from many countries
- Wildlife origin infections seen in cattle
- Ingestion, inhalation, abrasions, and transplacental
- Abortion storms may be seen after 5th month of pregnancy
- In bulls, targeted organ are seminal vesicles, testicles, and epididymis
- Calves of limited duration
- Cows persist for years in lymph nodes and mammary glands
Dx
- First calf abortion in heifers and replacement animals
- clusters of MZN positive coccobacilli in smears from cotyledons or other fetal abomasal content or uterine discharge
- Isolation and identification
- Colonial appearance
- MZN positive
- Agglutination with high-titred antiserum
- Rapid urease activity
- PCR
- Serological test for live animals
Serological test for milk or serum
- Brucella milk ring test: on bulk milk samples for monitoring but not reliable in large herds
- Rose-Bengal plate: screening agglutination requires confirmation
- Complement-fixation test: accepted confirmatory test
- Indirect ELISA: confirmatory test reliable
Tx and control
- Ineffective
- National eradication detection and slaughter
- Vaccination of young heifers
- Attenuated live (S19) (RB51), adjucanted 45/20 bacterin
34
Caprine and ovine brucellosis
- Brucella melitensis
- Mostly seen in Mediterranean area, Central Asia and South America
- Goats are ore susceptible
- High abortion rate in females, orchids in males, arthritis and hygromas.
Dx
- Based on clinical signs
- Direct examination of fluids with MZN
- Isolation and identification
- Serological testing
- Vaccines: MLV B. melitensis Rev 1 strain in kids and lambs up tp 6 mts of age.
35
Ovine Epididymitis
| -Brucella ovis
-B. ovis causes epididymitis and placentitis
C/S
- epididymitis and placentitis
- Reduced fertility
- sporadic abortions
- Increased perinatal losses
- Venereal transmission
- Unilateral or bilateral testicular atrophy with swelling and hardening of epididymis
Dx
- serological screening
- AGID test, complement-fixation and indirect ELISA
- Scrotal palpation
- PCR
- Semen PCR
Tx
-Vaccination of young rams by B. melitensis Rev 1 pr B. ovis bacterin
36
Porcine Brucellosis
- Brucella suis
- Ocassionally in the US
C/S
- Prolonged bacteremia
- Chronic inflammation
- Lesions in repro organs of sows and boars
- Lesions can be found in joints and bones
- Transmission by coitus and ingestion
- Abortion, stillbirths, neonatal mortality and temporary sterility
- Boars excreting brucellae in semen may have testicular abnormality
- Infection occurs in wild boar as reservoir
- Could be self-limiting
Dx
- Rose-Bengal plate
- agglutination test
- Indirect ELISA
- Test and slaughter policy main control measure
- a modified live vax B. suis not in US
37
Canine Brucellosis
-Brucella canis
C/S
- relatively mild and asymptomatic
- May cause abortion in dogs
- Prevalence could be higher than reported
- Males: orchitis and epididymitis
- rarely: lameness, paresis or paralysis due to discospondylitis
Dx
- Rapid slide agglutination test
- ELISA
- Agar gel immunodiffusion
- Culture
- PCR
Tx
- Early tx could be effective
- Tetracycline and aminoglycoside could be effective
- Long-term resolution is difficult
- Commercial vax not available
- Control based on serological detection
38
Human brucellosis
- Susceptible to all brucella spp. mentioned
- Via contact with secretions of infected animals
- Vax accidents
- Lab accidents
- Abortions not common
- Osteomyelitis is the most common complication
- Antimicrobial should start early
- Severe hypersensitivity following infection or accidental inoculation of vaccine
