MS Infecitons - Borrelia Flashcards
what disease does borrelia cause
Lyme
Features of borrelia
G - rod, spiral/curved, spirochetes, difficult to stain, difficult to grow or culture
Infectious route of borrelia
Borrelia burgdoferi, dogs & horses (cattle, humans, sheep & cats) causes Lyme disease
Origin of Borrelia Burgdorferi
Adapted from Ixodes ticks, reservoir is small rodents (white footed mice, voles, chipmunks)
Virulence factors of borrelia burgdoferi
Motility, resistance to innate inflammatory response, LPS analog - elicits inflammatory response - has no endotoxins. Outer surface proteins - shifting OSP can change impacting the immune recognition
How borrelia burgdoferi causes disease
Initial bite introduces bacteria to blood stream, spreads to multiple organs, immune response kicks in, ~95% of dogs will clear. 5% will have disease manifestations & weak endotoxin like activity
Borrelia burgdoferi LPS analog acts on
Monocytes, synoviocytes, keratinocytes and release IL-1 (cytotoxin)
IL-1 can target what organ or cells to respond
Hypothalamus - fever
Synoviocytes - collagenase + protease = joint destruction
Chondrocytes - prostaglandins -> bone resorption = joint damage
B & T lymphocytes - proliferation & aggregation, increase Ab synthesis = joint damage
Potential target organs of Lyme disease
Joints
Kidneys (dogs)
Lymph nodes
Muscle
Meninges (horses)
Specific diseases of Borrelia burgdorfergi in dogs
Lyme arthritis - fever, anorexia, lethargy, shifting leg lameness, lymphadenopathy - lameness in episodes
Lyme nephritis - rare & most aggressive. Immune- mediated destruction of kidneys
Specific diseases of borrelia burgdorferi in horses
Cases are often sub clinical
Low grade, sporadic fever, shifting lameness, myositis (immune response in muscles) depression, encephalitis, uveitis (secondary to inflammation caused by borrelia)
Specific diseases borrelia burgdorferi cause in humans
Rash around bite zone, fever, fatigue, arthritis, lymphadenopathy, peripheral nervous system
Or asymptomatic
Best method for diagnosing
Not really any
Best bet is serology - antibody detection
Changes in OSP can impact the tests by altering the immune mediated response / building the antibodies
Treating borrelia burgdorferi
Doxycycline or minocycline is preferred
Beta lactams or macrolides
Recheck in 30 days then 3-6m
How to control borrelia burgdorferi
Tick control! As they’re the vectors
Vaccinations against Lyme disease
Osteomyelitis
Inflammation of cortical bone, medullary cavity & periosteum
Can involved appendicular Skelton & Axial skeleton
Diskospondylitis
Concurrent infection of intervertebral disks & adjacent bony end plates
Common in dogs & cats
Infection usually from cystitis -> hematogenous
Routes of infection for osteomyelitis - hematogenous
Rare route of infection, occurs primarily in neonates & involves metaphyses - vascular part of bone where infection can spread
Can spread via bone to epiphyses, periosteum & joints
Routes of infection for osteomyelitis - post traumatic injury
Requires predisposing factors as bone is highly resistant to infection
Ischemia/necrosis/sequestrum formation
Bacterial contamination
Fracture instability
Foreign body implantation
Systemic/local change in immune response
Importance of biofilms in osteomyelitis
Matrix of bacteria called glycocalyx - community of slim/film
Protects bacteria from antibodies, phagocytes & antibacterial
Staph is predominant but can hide/mix with other films
Bacteria can co-exist & replicate = mixed infection
Implantation of foreign material can increase risk
Specific osteomyelitis in pigs
Strophic rhinitis
Combo of bordetella brochiseptica & pasturella multocida
Specific osteomyelitis in cows
Lumpy jaw, caused by actinmyces bovis
Diagnosing osteomyelitis
Physical exam
Lab finding - leukocytosis, increase Ca, P & ALP
Radiograph - not sensitive enough to be definitive
Cytology evaluation of exudates
Culture bone or bone marrow - aerobic & anaerobic
Treating osteomyelitis
Antibiotics - susceptibility testing, location of infection could make it difficult to reach
Antimicrobials will have little to no effect on chronic osteomyelitis- debridement, draining etc
