Test 3- Spirochetes Flashcards
Which of the following is incorrect about paucibacillary lesions?
A. seen in mycobacterial infections
B. This is due to lack of cell mediated immunity
C. Few Bacteria are seen in these lesions
D. Result in milder disease
B- in these lesions- cell mediated response
CELL MEDIATED IS THE KEY FACTOR in controlling the lesion
Use of mulitple antimicrobial agents in treating mycobacterial infections is to…
2 reasons
Minimize development of antimicrobial resistance
and
to cover all of the locations- extracellular or intracellular
Which mycobacterium species is mycobactin dependent for its growth?
M. avium subsp paratuberculosis
THIS IS WHAT IS USED FOR IDING this in culture
Which mycobacterium spp is widely present in soil and water?
M. avium complex
M. Bovis, leprae, and tuberculosis can be present because they can be obligate pathogens
Spirochete Morphology
• Capable of movement in environments with 5-15 times higher viscosity (translational, rotating, and flexing motion)
• Flagella in the periplasmic space
Axial filaments/endoflagella which insert at the end of protoplasmic cylinder
Number of flagella varies upon genus
Genus Brachyspira
Gram-negative(have LPS), strongly beta hemolytic, oxygen tolerant, anaerobic, loosely coiled, motile spirochete
Acute to chronic, highly infectious disease, most commonly found in grower and finisher pigs (8-16 weeks)
Multiple species of Brachyspira can colonize the porcine colon and cause disease typical of swine dysentery
• Can affect multiple species
Very heterogeneous species with many pathogens
B. Hyodysenteriae
Causes swine dysentery
Actively growing pigs (6-12 weeks of age)
B. pilosicoli; Causes Intestinal spirochetosis in animals and humans
Others with controversial role in diseases
B. intermedia, B. mudochii, B. innocens, B. canis
Virulence Factors and Transmission of Brachyspira
Virulence factors
Cytotoxin/Hemolysin LPS
Transmission is fecal-oral
Asymptomatic carrier pigs are the most important mode of transmission from farm to farm; mechanical vectors (boots, coveralls, vehicles, migratory animals and birds)
Pathogenesis of Brachyspira
Pathogenesis is complex and not completely understood
There is synergistic action between B. hyodysenteriae and other anaerobes normally found in the swine colon and cecum (mainly Bacteroides and Fusobacterium) required for clinical disease
Motile Brachyspira hyodysenteriae is chemotactically attracted to hog mucin > invades intestinal crypts and disrupts colonic epithelium > progressive erosion of superficial epithelium, excess mucus production, edema and hemorrhage of the lamina propria with pseudomembrane production > death from dehydration (malabsorption of water and electrolytes)
Thrombosis may occur due to absorption of bacterial endotoxins from gram-negative bacteria through the damaged colonic mucosa
Lesions and Symptoms of Brachyspira
Lesions in the large intestine only, often sharp line of demarcation at the ileocecal junction. Fibrinonecrotic pseudomembranous colitis with a granular, hyperemic mucosa in advanced cases
Bloody diarrhea, dehydration, and weight loss which was refractory to antibiotic therapy. Secretory diarrhea with gray to strawberry-colored feces and dehydration
Morbidity ~90%, Mortality ~40%
Can last for several weeks
Asymptomatic shedders are difficult to identify
What is a ddx of brachyspira?
Salmonella!
Diagnosis of Brachyspira
Direct staining and observation of loosly coiled spirochetes in clinical specimens (Fecal samples or tissues are stained with Wright’s Giemsa, Victoria Blue stain)
Anaerobic culture
PCR
Histopathology and Silver staining
(This condition must be differentiated from Salmonellosis)
Treatment and Control of Brachyspira
• Tiamulin, tylosin, gentamicin, nitrofurazone, lincomycin
Infected pigs develop immunity
• Whole cell bacterin vaccines are available
Treponema
- Treponema pallidum
- Syphilis in humans
- Can not be cultivated in vitro
Papillomatous digital dermatitis (PDD)
“Hairy Heel Warts” (HHW) (also known as Heel warts, Strawberry Foot Disease
Growing cause of lameness of cows in the U.S. dairy industry.
Economic loss due to treatment costs, decreased milk production,
lower reproductive efficiency, and premature culling.
Affects around more than 40 % of US dairy Herds
Treponema brennaborense???
Treatment of PDD
“Spraying feet of dairy cattle with antibiotic (tetracycline or lincomycin) solutions while they are in the milking parlor has generally been found to be the most cost effective method of treating HHW on a herd basis”
“Formaldehyde foot baths”
What are the problems associated with these two commonly used treatment methods?
RESISTANCE!
formalin problems- carcinogen
Treponema paraluis-cuniculi
Rabbit syphilis or Vent diseases in rabbits self-limiting disease
perineal and facial lesions;
infection may increase susceptibility to other infection Spread by direct or venereal contact- USALLY AROUND THE NOSE
Initial lesions are on the perineum and genitalia
Epidermal hyperplasia with erosions, ulcers; infiltrates of plasma cells, heterophils and macrophages.
Definitive diagnosis is by demonstration of spirochetes in typical lesions
SEXUALLY TRANSMITTED
Borrelia
Transmitted via arthropod vector
Grow slowly in specialized media (microaerophilic)
Linear chromosome( most have spherical)
B. burgdorferi: Lyme disease
B. anserina: avian borreliosis
B. recurrentis: relapsing fever borreliae
Borrelia virulence Factors
LPS
Antigenic Variation in Major outer surface lipoproteins (OSP)- MAIN ONE
CHANGE TO EXCAPE THE IMMUNE SYSTEM
In B. burgdorferi:
Osp C to Osp A in midgut of ticks & in culture
Osp A to Osp C in salivary gland of tick
Osp C in mammals early in infection
Lyme Disease
Identified in 1975 when a cluster of arthritis cases was diagnosed in children near Old Lyme, CT
Borrelia burgdorferi (sensu lato)> 11 genomospecies (3 from humans in US: burgdorferi, garneri, afzelii)
Genetic (strain) diversity among genotypes
Ixodes scapularis (eastern US
Ixodes. pacificus (western US)
Reported in humans, dogs, horses, cattle, sheep
Who plays a big role in transmitting Lyme Disease to humans and animals?
Deer, and white footed moose
Lyme Disease Transmission
Ticks become infected only when feeding on animal with sufficiently high level of bacteremia and only feed once prior to each molting
After tick ingests blood, spirochete up-regulates expression of an outer surface protein, which is essential for virulence in mammals
Spirochete moves from midgut to hemolymph to salivary glands
Transmission of spirochaete requires ~ 50 hrs.
Lyme Disease prevalenae
Most common vector borne bacterial disease in humans US. (>20,000 human cases reported per
year)
Antibiotic responsive, Non-fatal
Non-communicable
Geographically and seasonally limited
Both under-reported and over-diagnosed
Clinical syndromes vary depending upon
infecting genotype, age, immune status
Lyme Disease Pathogenesis
After inoculation into the skin,spirochetesmultiplytohighest numbers in the skin and disseminate via the bloodstream>Organisms spread through blood to joints, brain, nerves, eyes, heart, liver, kidneyIncubation period: 2 – 6 mo.
Canine Lyme Disease
Infection usually subclinical (95%)
Exposure common in endemic areas- Typical clinical signs in dogs are fever, acute arthritis, arthralgia and lameness. Sometimes accompanied by anorexia, lethargy and
depression. 344-7 )
(Appel 1990, Compendium Cont Educ Pract Vet 12: 617-26; Levy & Magnarelli 1992, J Am Vet Med Assoc 200:
CNS, heart, renal lesions and uveitis are less frequently reported and not reproduced experimentally in dogs
Dx of Lyme Disease
Direct detection of organism in host tissues(Poor sensitivity)
Culture and isolation(slow)
Serology- remember only tells exposure
Western Blot
SNAP test (EIA) – point of care test
Multiplex ELISA for dogs and horses(OSPA, OSPB, OSPC)
Paired titer helpful(antigenic variation is a problem)
How to interupt Test results
Clinical signs and Positive test: infected
Healthy and negative test: not infected
Clinical signs and negative test: evaluate for underlying disease, retest
Healthy and positive test:likely to be infected subclinically.
In endemic area treatment is preferred,innon-endemic
usually not pursued
Should Healthy Dogs be Screened?
ACVIM Small Animal Consensus Statement: = could not reach a consensus Provided a list of pros and cons in testing this population
Treatment and Control
Doxycycline
Vector control in dogs
Vaccine for dogs (bacterin, subunit Osp A)reduces (~3%) incidence of disease in endemic region, does not prevent infection.- VACCINE ACTS IN TICK’S BODY- Stops replication in the tick
Antibodies against OSP A antigen act on found on organisms present in midgut of ticks, vaccine may block transmission by interfering with OspA to OspC conversion. ie. antibodies produced in the dog must be delivered to the tick to exert this effect
Letospira Classification
>250 serovars based on carbohydrate component of the bacterial lipopolysaccharide- maintanied in the renal tubuloles
Organized in ~23 serogroups
(~22 genomospecies)
Serovar and species concept not always in agreement isolates of one serovar may belong to different genomospecies isolates of one genomospecies may belong to different serovars
Leptispira Habitat
- Pathogenic species maintained in the renal tubules or genital tract of reservoir animals
- Reservoir animals excrete the bacteria through urine and contaminate the environment (water)
- Pathogenic species survive for short period of time in ponds, rivers, surface waters, moist soil, mud
- Direct contact with urine or contaminated water results in infection in susceptible hosts
BIGGEST host for leptospira
RATS
What is the main target organ for Leptopira?
Kidney and liver
Leptospira is a _____
Leptospira is a ONE HEALTH PROBLEM
HUMANS: Flu like illness and protean manifestations
Complications from renal, pulmonary, hepatic and CNS disease
IN LIVESTOCK : Disease of production and reproduction
COMPANION ANIMALS :
Disease similar to humans
Virulence Factors of Leptospira
Cell associated:
- *- endoflagella- helps with motility**
- outer membrane proteins - LPS
Extracellular:
- hemolysins (in some serovars)
- protein cytotoxins?
Pathogenesis of leptospira
Penetrates epithelial barriers (incubate 4-20 days) Bacteremia (for up to 7 days)
Enter liver, kidney, spleen, CNS, genital tract Antibodies develop (extent and duration varies)
In Maintenance hosts— Long term shedding; doesn’t make them sick
Incidental hosts—– Recovery with short term shedding in urine- some have severe disease
Leptospirosis in Dogs
LIVER AND RENAL PROBLEMS
LESIONS IN KIDNEYS- Tublointenstintal injury
Mild or no signs of disease, to severe illness or death.
Acute febrile illness
Renal or hepatic injury, uveitis, pulmonary hemorrhage, abortion.
(polyuria, polydipsia, dehydration, vomiting, diarrhea, inappetence, lethargy, or abdominal pain)
Signs hepatic and Renal failure, including icterus.
Bleeding abnormalities and disseminated intravascular coagulation(DIC)
Dogs surviving acute renal tubulointerstitial injury may have residual chronic kidney injury that progresses over months to years, culminating in signs of decompensated chronic kidney disease.
spirochetosis
Brachyspira
Papillomatous digital dermatitis( PDD)
aka Hairy Heel Warts or Strawberry foot disease
Treponema brennaborense???
