Infectious diseases Flashcards
Describe the pathogenesis of Brucella canis
Infects phagocytes and suppresses TNF-alpha –> disrupts bactericidal activity of NK cells and macs–> replicates within cell –> bacteremia
How does Brucella canis infect canine hosts?
Penetration through mucous membranes (vaginal discharge and semen have highest concentration of organisms)
What are the most common signs of canine Brucellosis?
Reproductive failures, abortion
Describe the acid-fast staining pattern of Actinomyces
Non-acid-fast
Where is actinomyces normally found?
It is normal flora in the oral cavity, GIT, and genital tract
Describe typical lesions of actinomycosis in dogs
Cervicofacial or truncal/limb SQ nodules, pneumonia and pyothorax may be seen
Describe typical clinical signs of actinomycosis in cats
Pyothorax> SQ lesions
Describe the culture characteristics of actinomyces
Fastidious and can be difficult to grow on culture, should be grown anaerobically
(positive culture does not mean disease since it’s a commensal)
Describe cytologic findings for actinomyces
Suppurative to pyogranulomatous inflammation, dense mats of filamentous bacteria, sulfur granules
What is the treatment of choice for actinomyces?
High doses of penicillins for prolonged periods of time (other options: clinda, doxycycline, erythromycin, chloramphenicol are options), +/- surgery
What is the prognosis for actinomyces?
Low mortality, cure rate as high as 90%
Describe the acid-fast staining pattern of Nocardia
partially acid-fast
Is Nocardia an aerobe or anaerobe?
Aerobe
Where is Nocardia typically found?
Soil saprophyte, fresh and salt water, decaying plant matter
What is a predisposing factor to the development of Nocardiosis?
immunosuppression or other comorbidity (this is less common in cats)
Describe the culture characteristics of Nocardia
Usually cultured, aerobic, Sabouraud’s or blood agar
What is the treatment of choice for Nocardia?
Surgery and antibiotics (sulfas)
What is the prognosis for Nocardia?
Guarded, moderate to high mortality
What are the 4 clinical forms of Actinomyces infection?
Cervicofacial, thoracic, abdominal, SQ
How is Nocardia acquired?
Inhalation or inoculation
Where would Nocardia be expected to be more prevalent geographically?
SW US, Australia (dry, dusty, windy)
What are the clinical forms of Nocardia infection?
Pulmonary
Disseminated
Cutaneous/SQ
Are sulfur granules more common with Actinomyces or with Nocardia?
Actinomyces - sulfur granules on FNA should prompt suspicion of Actinomyces
How does Nocardia spread?
Direct or hematogenous
How does Actinomyces spread?
Direct via adjacent tissue
What antibiotic could be considered if you are struggling to differentiate between Nocardia and Actinomyces?
doxycycline
What do anaerobic bacteria fail to produce that prevents their growth in oxygen?
They don’t produce superoxide dismutase
What part of gram-negative anaerobic bacteria results in inflammation?
LPS with endotoxic activity (responsible for endotoxic shock in septicemia)
What part of gram-positive anaerobic bacteria results in inflammation?
Thick peptidoglycan layer
What are the cell wall components of fungi?
Manno-proteins, beta-glucan, chitin
Will Mycoplasma stain with gram stain?
No because it lacks a cell wall (this lack of cell wall also makes it resistant to cephalosporins and penicillins)
What organism has a “fried egg” appearance on culture media?
Mycoplasma
What is the defining characteristic of L form bacteria?
They lack a cell wall
What antibiotics would you consider using to treat L form bacteria?
Macrolides, tetracyclines, chloramphenicol, FQ (resistant to beta lactams due to lack of cell wall)
What strain of Streptococcus is likely to be more pathogenic?
beta-hemolytic (Groups A, B, C, E, G, L, M)
Where is a dog or cat likely to acquire group A Strep?
Humans (shedding via respiratory droplets; S. pyogenes, S. pneumoniae)
What species of Strep has been implicated in canine and feline necrotizing fasciitis?
Strep canis (Group G)
What are the virulence factors in Strep canis?
Streptolysin O gene, M-protein (inhibits phagocytosis by neutrophils and macs)
What antibiotic has been implicated in triggering Streptococcal toxic shock syndrome?
Enrofloxacin
Is Streptococcus gram positive or gram negative?
Gram positive
How does the cell wall of gram-negative bacteria differ from that of gram-positive?
Gram negative: thin peptidoglycan layer surrounded by an outer lipopolysaccharide layer (LPS)
Gram positive: thick peptidoglycan layer but no outer layer
What is the virulence factor of Rhodococcus equi in horses?
Plasmid that encodes virulence protein VapA, allowing it to persist within macrophages
Define the bacterial characteristics of Erysipelothrix rhusiopathiae
Gram-positive, facultative anaerobe, rod-shaped
Define the pathogenesis of Dermatophilus congolensis
Motile zoospore attracted to CO2 on skin surface –> germinates on skin to produce a filament which invades epidermis and proliferates
What culture media should be used for Dermatophilus?
Blood agar (Not MacConkey or Sabouraud’s)
What category of Staph tends to have higher virulence and is therefore a good indicator of pathogenic potential?
Coagulase positive (Staph aureus, Staph pseud, Staph schleiferi subsp coagulans)
What specific type of coagulase negative Staph has a higher potential to be pathogenic compared to other CoNS?
Staph schleiferi subsp scheiferi
Name 5 characteristics of the skin that make dogs more susceptible to pyoderma than cats and humans.
1) Thin skin
2) Compact stratum corneum
3) lack of intercellular lipids
4) lack of lipid follicular plug
5) higher pH
How does Staph hyicus cause disease in pigs?
Exfoliative toxins (Exh, SHET) digest desmoglein-1 in the epidermis
(Greasy Pig Disease)
What species serves as a reservoir for MRSA in the US?
Horses (harbor MRSA strain USA 500)
In what cell type would you find Bartonella?
RBC
What is the best diagnostic test for Bartonella?
Blood culture, tissue culture
What is the primary species of Borrelia isolates in the US?
B. burgdorferi (Lyme disease)
What is the vector for Borrelia?
Ixodes scapularis/Deer tick/Black-legged tick
(and other Ixodes ticks)
Describe the pathomechanism of transmission of Borrelia from tick to host
Spirochetes multiply in tick while attached to reservoir host –> crosses tick gut into hemolymph –> disseminates to tick salivary glands –> inoculated into host dermis during bite –> spirochetes replicate and migrate through skin
What proteins allow for spirochetes to migrate from tick mid-gut to salivary gland before inoculating into the host skin?
Downregulation of OspA (outer surface protein) and increased expression of OspC (blocks clearance of spirochetes so they can disseminate)
What species are the reservoir for Borrelia?
Mammals (esp white footed mouse and other small mammals), birds
How long does a tick need to be attached in order to spread Lyme disease?
24-48 hours
What does a SNAP4Dx detect in Lyme disease?
presence of antibodies to the C6 peptide of Borrelia (encoded by the IR6 gene sequence in the variable surface lipoprotein component)
In what cell type would you find Ehrlichia?
leukocytes
What is the primary vector for Ehrlichia?
Rhipicephalus sanguineus (Brown dog tick)
What are the dermatologic signs of Ehrlichia?
Petechiation, ecchymoses
In what cell types would you find Anaplasma?
Leukocytes, RBCs, endothelial cells, platelets
What are possible dermatologic signs of RMSF?
Edema and hyperemia of lips, penile sheath, scrotum, pinnae, extremities; vesicles and macules on buccal mucosa, cutaneous necrosis
What are the clinical signs of impetigo?
Non-follicular superficial pustules (usually glabrous areas)
What organisms would you expect to find in necrotic skin with crepitus?
Bacteroides, Clostridium (gas-producing bacteria)
What is the most common bacteria found in bite wounds?
Pasteurella multocida
Is Staph gram positive or gram negative?
Positive
True or false: M. canis is part of the normal skin microbiome of dogs and cats
False
What cat breed is predisposed to dermatophytosis?
Persian
What dog breeds are predisposed to dermatophytosis?
Yorkie
Working dogs (GSP, fox terrier, Lab, etc)
True or false: FIV and FeLV affected cats are at increased risk for dermatophytosis
False
What is the infective form of dermatophytes?
Arthrospores/arthroconidia
What is the typical source of Trichophyton infection?
Rodents and rodent burrows
What is the typical source of Microsporum gypseum infection?
Contaminated soil
What is required in order for dermatophytes to cause infection?
Skin microtrauma
What endoproteases are secreted by dermatophytes?
Subtilisins
Fungalysins
What is the function of fungal exoproteases?
Digest keratin into peptides and AAs
What type of immune response is necessary to cure dermatophytosis?
Cell-mediated
What type of dermatophyte lesion is associated with tissue grains?
Pseudomycetomas
Mycetomas
What genus of dermatophyte fluoresces?
Microsporum (plus T. schoenleinii)
What causes fluorescence of M. canis?
Pteridine within hair cortex/medulla
True or false: Hair shafts can fluoresce even when dermatophyte infection is cured.
True
What is the recommended mounting medium when examining trichogram for dermatophyte spores?
Mineral oil
True or false: The combination of miconazole and chlorhexidine is more effective against dermatophytosis than either ingredient alone.
True
What are the currently recommended topical treatments for dermatophytosis and how often should they be applied?
Twice weekly
Lime sulfur
Enilconazole (not available in USA)
Miconazole + chlorhex
What is considered the “mycologic cure” in dermatophytosis?
Two negative consecutive cultures taken at least 2 weeks apart
What are the most effective and safe oral treatments for dermatophytosis?
Itraconazole (NON-compounded)
Terbinafine
How often should bleach solutions be made when treating dermatophytosis in the environment?
At least once weekly
What are 3 important steps in disinfecting nonporous surfaces of dermatophytosis?
1) Mechanical removal of debris
2) Detergent application
3) Application of disinfectant
What water temperature should be used when washing laundry to eliminate dermatophytosis?
Any temp (two washes on longest cycle)
How often should environmental decontamination be done to help eliminate Ringworm?
Twice weekly
What is the primary dermatophyte pathogen in humans?
Trichophyton rubrum
A modified Fite-Faraco stain is applied to a tissue sample and is positive. You are trying to differentiate Nocardia from Actinomyces - which is most likely?
Nocardia
(Fite-Faraco is a modified acid fast stain)
Is Actinobacillus gram-negative or gram-positive?
Gram-negative (different from Actinomyces and Nocardia)
Is Actinobacillus aerobic or anaerobic?
Aerobic
What is another name for bacterial pseudomycetoma?
Botryomycosis
What bacteria are usually associated with pseudomycetoma formation??
Coagulase-positive Staph
Is Dermatophilus congolensis an aerobe or anaerobe?
Aerobe (or facultative anaerobe)
What is the most common aerobic bacteria isolated from cat bite wounds?
Pasteurella multocida
What bacterial infection has a “bundle of grapes” appearance clinically?
Botryomycosis
Is Mycobacteria an aerobe or anaerobe?
Aerobe
What virulence factors are responsible for causing the host granulomatous response in Mycobacterial infections?
Cord factor
Wax D
What subspecies of Mycobacteria are tuberculous?
M. tuberculosis
M. bovis
M. microti
How is M. bovis typically transmitted?
Through the GI tract
What are the most common body sites for localization and shedding of M. bovis?
Ileocecal LN
What body system is most likely to be affected by M. tuberculosis?
Lungs
What addition to culture media can improve the growth of M. tuberculosis and inhibit the growth of M. bovis?
Glycerol
Is Mycobacteria acid-fast?
Yes
What is the recommended treatment for animals diagnosed with M. tuberculosis?
Euthanasia (due to zoonotic risk)
Where are bacteria of the M. avium complex usually found?
Bird feces
Ubiquitous in soil/water
How is Mycobacterium avium complex usually transmitted?
Ingestion of organism
What are the typical cytology findings of Mycobacteria?
Organisms within macrophages
What are the 4 primary causative agents of feline leprosy?
Mycobacterium lepraemurium
Mycobacterium visible
Mycobacterium lepraefelis
Mycobacterium tarwinense
What breed is predisposed to canine leproid granuloma?
Boxers (short-coated breeds overrepresented)
You find negative-staining bacilli within macrophages on cytology of nodules from a Boxer’s head. What is the most likely diagnosis?
leproid granuloma caused by Mycobacteria
What is the treatment recommendation for canine leproid granuloma?
Benign neglect- many will spontaneously regress in 1-3 months
Surgery
Rifampin/doxy/clarithromycin
Is there a public health risk in canine leproid granuloma?
No
What is the most common clinical presentation of rapidly-growing Mycobacteria?
Panniculitis
What is the gold standard culture medium for identification of rapidly growing Mycobacteria?
Broth microdilution
Describe the acid-fast staining characteristics of Mycobacteria.
Positive on acid-fast
What is the geographical distribution of Mycobacterium tarwinense?
Australia
What body region(s) is typically affected by Mycobacterium tarwinense?
Head and ocular tissue
What body region(s) is typically affected by Mycobacterium lepraemurium?
Head (without significant ocular involvement)
Forelimbs
What is the proposed transmission of Mycobacterium lepraemurium?
Rodent bites
What subspecies of Mycobacterium typically affects older cats (>9 years) with feline leprosy?
M. lepraefelis
What species of Mycobacterium typically affects younger cats (<3 years) with feline leprosy?
M. lepraemurium
What type of feline leprosy is associated with an unfavorable prognosis?
Mycobacterium lepraefelis
What species of feline leprosy is suspected to be associated with immunosuppression/comorbidities?
M. lepraefelis
What species of Mycobacterium is associated with systemic involvement in cases of feline leprosy?
M. lepraefelis (liver)
Where does the disease process occur for rapidly-growing Mycobacteria species?
SQ fat (panniculitis)
Where does the disease process occur for slow-growing Mycobacteria species?
Dermis (nodules)
What is the most common Staph isolate in horses?
Staph aureus
What toxin produced by Staph influences bacterial binding?
Protein A
What gene confers beta-lactam resistance to Staph?
mecA
What are the 3 members of the Staph intermedius group?
Staph intermedius
Staph pseudintermedius
Staph delphini
Which gene is targeted using PCR to help differentiate coagulase-positive Staph species?
thermonuclease (nuc)
What sites are swabbed to determine Staph pseud carriage on dogs?
Oral mucosa
Perineum
What is the most commonly found Staph species colonizing cats?
Staph felis/Staph simulans
What is the most common Staph intermedius group member found on horses?
S. delphini
What cytotoxins are produced by Staph pseudintermedius?
Luk-1 (leukotoxic to PMNs)
alpha-hemolysin (hemolysis)
beta-hemolysin (hemolysis)
What exfoliative toxins does Staph pseud produce?
SIET (Staph pseud exfoliative toxin)
EXI (ExpA)
ExpB
What Staph toxins cause degradation of Dsg-1?
EXI, ExpB
What enterotoxins are produced by Staph pseud?
SEC (Staph enterotoxin C)
se-int
What is the function of MSCRAMMs in relation to Staph?
These are Staph proteins which play a role in bacterial attachment to the host ECM
What Staph pseud surface proteins (Sps) mediate Staph adherence to canine corneocytes?
SpsD
SpsO
What Staph pseud surface proteins (Sps) mediate Staph adherence to the ECM?
SpsD
SpsL
What Staph pseud gene encodes tetracycline resistance?
tet(M)
What Staph pseud gene encodes macrolide resistance?
erm(B)
What genera of fungus are typically found on the skin of dogs and cats?
Alternaria
Cladosporium
Epicoccum
Which breed of cat has higher carriage rates of Malassezia?
Devon Rex
Sphynx
Which special fungal stain will stain both living and nonviable fungi?
GMS
What can be stained by GMS that would not stain with PAS?
Oomycetes
What is the typical size of Malassezia?
3-8 um
What is the typical morphology of Candida?
3-4 um
ovoid shape
What is the typical morphology of dermatophytes?
2-3 um wavy parallel-walled hyphae
2 um arthrospores
What is the typical morphology of white-grain eumycotic mycetomas?
2-7 um septate, non-pigmented hyphae
What is the morphology of black-grain eumycotic mycetomas?
2-7 um pigmented hyphae
Septate
What is the morphology of hyalohyphomycosis?
2-6 um hyphae
Septate
parallel walls
Occasional acute-angle branching
What is the morphology of Aspergillus spp?
2-6 um hyphae
Septate
Parallel walls
Frequent acute angle branching
What is the morphology of mucorales?
8-20 um hyphae
Sparse septae
Nonparallel walls
Irregular branching
What is the morphology of entomophthoromycosis?
6-20 um hyphae (Basidiobolus)
5-12 um hyphae (Conidiobolus, shown in image)
Sparsely septate
Nonparallel walls
Rare irregular branching
Eosinophilic sleeve around hyphae
What is the morphology of phaeohyphomycosis?
2-10 um pigmented hyphae with beaded appearance
4-15 um yeast-like form
+/- branching
What is the morphology of chromoblastomycosis?
10-20 um pigmented Medlar bodies
Transverse and longitudinal septae
What is the morphology of Lagenidium?
8-25 um
Nonparallel walls
Irregular branching
Rare septae
Does not stain with PAS
What is the morphology of Pythium?
2-7 um
Nonparallel walls
Irregular branching
Rare septae
Does not stain with PAS
What is the causative agent in “thrush”?
Candida
What is unique about Candida growth compared to other opportunistic fungi?
It grows as yeast, hyphae, and pseudohyphae simultaneously
What is the morphology of Blastomyces?
5-20 um yeast
Double contoured wall
Broad-based budding
What is the morphology of Histoplasma?
2-4 um round yeast
Clear halo
Thin cell wall
What type of fungal stain is best to highlight Histoplasma?
GMS
What is the morphology of Cryptococcus?
2.5-20 um oval yeast
Thick capsule (“soap bubble”)
What stain is best to highlight Cryptococcus?
Mucicarmine
What is the morphology of Coccidiodes?
20-80 um spherules containing endospores
Double contoured wall
What is the morphology of Sporothrix?
3-10 um long cigar-shaped yeasts
Yeasts often in macrophages
What is the most common dermatophyte in pigs?
M. nanum
What is the most common dermatophyte in cattle?
Trichophyton verrucosum
Define hyalohyphomycosis.
Fungal infection caused by opportunistic, non-dermatophytic saprophytes that grow as NON-PIGMENTED hyphae in tissue
What are the features of eumycotic mycetomas?
1) tumefaction
2) tissue grains within exudate
3) draining tracts
What are the typical causative agents of black grain eumycotic mycetomas?
Curvularia lunata
Curvularia geniculata
Cladophialophora bantiana
Phialophora oxyspora
What are the typical causative agents of white-grain eumycotic mycetomas?
Pseudallescheria boydii (Scedosporium)
Penicillium dupontii
What is usually surrounding eumycotic mycetomas on histopathology?
Splendore-Hoeppli
Is Aspergillus pigmented or non-pigmented?
Non-pigmented (looks like hyalohyphomycosis)
Are Mucorales pigmented or non-pigmented?
Non-pigmented
Are entomophthorales pigmented or non-pigmented?
Non-pigmented
What are the primary causes of entomophthoromycosis?
Conidiobolus
Basidiobolus
What are the typical clinical signs of Coniodiobolus coronatus in horses?
Rhinitis and sinusitis
How could you differentiate an oomycete infection from entomophthoromycosis on histopath?
Entomophthoromycosis would stain with PAS, oomycetes do not
Define phaeohyphomycosis
Cutaneous/SQ infection caused by PIGMENTED opportunistic fungal hyphae that do not result in tissue grain formation
What stain could be used to highlight melanin within fungal cell walls when they don’t stain routinely on H+E, aiding in the dx of phaeohyphomycosis?
Fontana-Masson
What type of infection is associated with sclerotic bodies/Medlar bodies?
Chromoblastomycosis (a subset of pigmented fungi)
What type of fungi do oomycetes most closely resemble?
Entomophthorales (Conidiobolus spp, Basidiobolus spp)
What oomyctes cause oomycosis?
Lagenidium
Pythium
What organism are oomycetes most closely related to?
Algae
What is the primary component of an oomycete cell WALL?
Cellulose
What is the primary component of the oomycete cell MEMBRANE?
B-glucan
What is the primary component of the fungal cell WALL?
Chitin
What is the primary component of the fungal cell MEMBRANE?
Ergosterol
True are false: most animals with oomycete infections are immunocompromised.
False
What clinical feature helps differentiate Lagenidium from Pythium?
Lagenidium infrequently involves GIT and more frequently involves lymphadenopathy
What oomycete is associated with slowly progressive disease and a better prognosis?
Paralagenidium (karlingii)
What stain is best to highlight infection caused by oomycetes on histopath?
GMS
Why is PAS stain a poor choice for highlighting oomycetes?
They have no chitin in the cell wall
Define dimorphic fungi
Fungi that exist as hyphae in culture and as yeasts/spherules in tissue
Are dimorphic fungi opportunistic or primary pathogens?
Primary pathogens
Name 5 dimorphic fungi of pathogenic significance in animals
Histoplasma
Coccidiodes
Cryptococcus
Blastomyces
Sporothrix
Where is Histoplasma usually found in the environment?
Organic matter in bat feces
What species of Histoplasma typically infects equids?
H. farciminosum
Where in the environment is Blastomyces typically found?
Moist, acidic soil near woods or decaying vegetation
Where in the environment is Coccidiodes usually found?
Arid soil in SW USA (Valley Fever)
Where in the environment is Cryptococcus usually found?
Nitrogen-rich alkaline debris contaminated with pigeon feces
Where in the environment is Sporothrix usually found?
Tropical/subtropical soil and decaying plant matter (central/south America)
Do dimorphic fungi usually cause cutaneous or systemic disease?
Systemic (cutaneous is uncommon)
How are dimorphic fungi usually acquired?
Via inhalation (exception: Sporothrix)
What dimorphic fungi preferentially affects bone?
Coccidiodes
What fungal organism is associated with endosporulation?
Coccidiodes
What is the likely organism demonstrated in this image?
Coccidiodes (endosporulation within spherules)
What is the likely organism demonstrated in this image?
Cryptococcus (thick clear capsule)
What is the organism highlighted in this image and what is the stain demonstrated?
Cryptococcus, mucicarmine
What type of organism is Leishmania?
Protozoa
How is Leishmania transmitted?
Bite from Phlebotomus and Lutzomyia sandflies
What are the 3 forms of leishmaniasis in humans?
Cutaneous
Mucocutaneous
Visceral
Describe the life cycle of Leishmania
1) Lives in host macrophages as amastigotes –>
2) amastigotes multiply and rupture out of macs –>
3) sandfly ingests amastigote after sucking blood from host –>
4) transform into flagellated promastigote form in sandfly gut –>
5) promastigotes multiply and detach from gut epithelia to travel to mouthparts –>
6) promastigotes injected into host skin when sandfly bites and become amastigotes again
What cytokines have induced antileishmanial activity of macrophages?
IFN-gamma
IL-2
TNF-a
What claw manifestation may be seen with canine Leishmania?
Onychogryphosis (hypertrophy and abnormal curvature of claws)
True or false: Dogs with cutaneous signs of Leishmania often have concurrent visceral disease
True
What are the most common cutaneous presentations for canine leishmaniasis?
1) Exfoliative dermatitis with silver scaling and alopecia
2) Ulcerative dermatitis over bony prominences, paws, MCJ, pinnae
What are the most common signs of visceral involvement in canine leishmaniasis?
Weight loss
Muscle atrophy
What is the most common cause of death in canine leishmaniasis?
Renal failure due to immune complex deposition
True or false: Leishmania parasites are usually not found on blood smear
True
What tissue is most likely to yield positive PCR for Leishmania?
Bone marrow/LN (>skin>conjunctiva>buffy coat>whole blood)
What stain allows for best detection of Leishmania amastigotes on cytology?
Giemsa
What are the nine inflammatory patterns that have been associated with cutaneous leishmaniosis?
1) Superficial perivascular dermatitis
2) Deep perivascular dermatitis
3) Granulomatous perifolliculitis
4) Interstitial dermatitis
5) Suppurative folliculitis
6) Lichenoid interface dermatitis
7) Lobal panniculitis
8) Nodular dermatitis
9) Intraepidermal pustular dermatitis
What prevention measures are recommended for Leishmania?
Permethrin, imidacloprid
Keep dogs inside at dusk and dawn
Vaccination
True or false: Most dogs treated for Leishmaniasis are cured.
False - most remain carriers despite symptoms resolving
What breed is a reservoir for visceral leishmaniasis in North America?
Foxhounds
Is Actinomyces gram-positive or gram-negative?
Gram-positive
What is the length of treatment for Actinomycosis?
Weeks-months past clinical resolution
What species of Nocardia usually affects humans, dogs, and cats in the SW US?
Nocardia brasiliensis
What species of Nocardia usually affects dogs and cats from the western US and Australia?
Nocardia nova
What form of nocardiosis is most common in humans?
Pulmonary
What form of nocardiosis is most common in cats?
Cutaneous/SQ
What atypical bacterial infection is usually associated with a mixed bacterial population?
Actinomycosis
Define rapidly-growing mycobacteria
Mycobacteria that form colonies on solid media within 7 days
What are the three syndromes of rapidly-growing Mycobacteria in dogs and cats?
1) Panniculitis (most common)
2) Pyogranulomatous pneumonia
3) Disseminated systemic disease
Would a rapidly growing Mycobacterial infection prefer a fat cat or a skinny cat?
Fat cat – prefers higher adiposity
What species of Leishmania is usually associated with cutaneous/MC disease?
L. braziliensis
What type of T-cells are protective against Leishmania infection and can lyse infected macrophages?
CD8+ (Cytotoxic)
What determines whether a dog infected with Leishmania will develop disease?
Immune response at time of inoculation
Describe the structure of canine distemper virus
enveloped ssRNA virus
What virus is associated with hard pad disease?
Canine distemper virus
What is another name for porcine herpesvirus-1?
Pseudorabies
What is the structure of porcine herpesvirus-1?
enveloped dsDNA alpha-herpesvirus
What species is the main reservoir for Pseudorabies?
Pigs
What are the main clinical signs of Pseudorabies in dogs?
Intense upper body pruritus
Ptyalism
What is the prognosis for Pseudorabies in dogs?
Grave - death within 48 hours of CS
What is the structure of feline herpesvirus-1?
ds DNA virus with glycoprotein-lipid envelope
What is the structure of feline calicivirus?
small non-enveloped ssRNA virus
What virus is associated with URI, oral ulcers, and acute lameness in cats?
Calicivirus
What is the structure of papillomavirus?
small, non-enveloped, dsDNA virus
What type of immunity is necessary for regression of papillomas?
Cellular
What genes encode for viral capsid proteins in papillomavirus?
L1, L2
What gene regulates viral DNA replication in papillomavirus?
E1
What gene activates transcription in papillomavirus?
E2
What gene modulates the immune response of infected cells in papillomavirus?
E3
What gene disrupts cytokeratins and facilitates viral release in papillomavirus?
E4
What genes are oncogenes responsible for cell immortalization in papillomavirus?
E6, E7
How does papillomavirus gene E7 cause cell immortalization?
binds and inhibits retinoblastoma (Rb), a tumor suppressor protein
Describe the pathogenesis of canine papillomavirus
Virus infects basal KC –> genome replication in S. spinosum and S. granulosum –> release of new infectious virus in keratinized squames
What are the cytopathic effects of papillomavirus?
1) Acanthosis and hyperkeratosis due to increased mitosis
2) Formation of koilocytes in upper S. spinosum
3) Giant keratohyalin granules in SG
4) Intranuclear inclusion bodies
5) Expanded blue-gray cytoplasm with enlarged nuclei and marginated chromatin
What dog breeds are predisposed to exophytic cutaneous papillomas?
Kerry blue terriers
Cocker spaniels
What breeds are predisposed to pigmented viral plaques?
Pugs
Miniature Schnauzers
What is the typical age of onset for feline cutaneous papillomas?
Middle-aged and older (unlike dogs)
What test would be recommended to confirm a lesion is viral?
IHC
What papilloma syndrome in dogs usually regresses on its own?
oral papillomatosis (takes ~3 months)
Which cell receptors recognize dsRNA viruses?
TLR3
Rig-like receptors
Which TLRs recognize ssRNA viruses?
TLR7
TLR8
Which receptors detect DNA viruses?
TLR9
Which cytokine is produced within hours of virus invasion, prior to adaptive immunity?
type I interferons (IFN-a, IFN-beta)
What is the primary virus-neutralizing antibody?
IgG
What protein allows distemper virus to penetrate host cells?
H protein
What protein allows distemper virus to fuse infected and noninfected cells?
F protein
Where are inclusion bodies typically found in distemper virus?
Intracytoplasmic > intranuclear
What papillomavirus is associated with canine oral papillomas?
CPV-1
How is FeLV transmitted?
Saliva (food bowls, grooming)
Describe the structure of FeLV
enveloped ssRNA
What viral family is FeLV a member of?
Retrovirus
What IHC stain can be done to diagnose FeLV?
gp70
How is FIV transmitted?
Cat bites
What virus is associated with cutaneous horns in cats?
FeLV
What virus family is distemper a member of?
Paramyxovirus
What is the reservoir for feline poxvirus?
Rodents
Is feline poxvirus zoonotic?
Yes - fatal to immunocompromised humans
Is feline poxvirus reportable?
Yes
What is the causative agent of feline poxvirus?
Cowpox
Where are inclusion bodies of poxvirus found?
Intracytoplasmic in KC (eosinophilic inclusions)
Describe the structure of feline poxvirus
enveloped dsDNA
What is another name for “orf?”
Contagious ecthyma
Contagious viral pustular dermatitis
Is Orf zoonotic?
Yes - painful umbilicated papules/nodules
Is Orf reportable?
No
What is the seasonal distribution for feline poxvirus?
summer and fall
What is the primary causative agent of feline herpesviral dermatitis?
FHV-1
True or false: Oral lysine has been demonstrated to be of major benefit in treatment of feline herpesvirus
False
What papillomaviruses are associated with cutaneous papillomatosis in dogs?
CPV-1
CPV-2
CPV-6
CPV-7
Are dogs who have recovered from oral papillomatosis usually reinfected?
No- they are immune to reinfection
What breeds are predisposed to cutaneous inverted papillomas?
Beagles
Bernese Mt Dogs
Cocker Spaniels
Kerry Blue Terriers
Great Danes
Irish Setters
Whippets
What CPV are associated with pigmented viral plaques?
CPV 3-5, 8-12, 15, 16, 18
What is the causative agent of feline sarcoids?
Bovine papillomavirus-14
What virus has been associated with feline bowenoid in situ carcinoma?
Feline papillomavirus-2
Describe the structure of FIV
enveloped ssRNA
What is the structure of Orf virus?
enveloped dsDNA
Where are inclusions found in feline herpesvirus?
Intranuclear (basophilic)
What virus has been associated with exfoliative erythema multiforme following URI?
FHV-1
Where does calicivirus remain latent in cats?
Oropharynx
Tonsils
Which virus has a hemorrhagic virulent form in cats?
Calicivirus
Which T-cell subset is essential in the cell-mediated immunity to fight papillomavirus?
CD4+ (T-helper)
What is a typical history in a cat with cutaneous fibropapillomas/feline sarcoids?
Exposure to cattle
Are Rickettsia gram-positive or gram-negative?
Gram-negative
What organism typically transmits Rickettsia ricketsii?
Dermacentor andersoni (Rocky Mt wood tick)
Dermacentor variabilis (American Dog tick)
What organism typically transmits Ehrlichia canis?
Rhipicephalus sanguineous (Brown dog tick)
What species is the definitive host of Toxoplasma?
Cats
In what cells would you find toxoplasma organisms?
Macrophages
What species is the definitive host of Neospora?
Dogs and coyotes
A dog is presented with multisystemic disease and pyogranulomatous dermatitis. What 2 organisms should be evaluated via serology?
Neospora
Toxoplasma
What breed has the highest incidence of Babesia canis?
Greyhounds
What breed has the highest incidence of Babesia gibsoni?
Pitbulls
What is the typical distribution of skin lesions in Leishmania?
Head
Pinnae
Extremities
What is typically the earliest cutaneous sign of RMSF in dogs?
Edema and hyperemia of extremities
In what cells does Rickettsia replicate?
Endothelial cells
What serves as the greatest human health risk in a dog with RMSF?
Exposure to tick feces and hemolymph (use forceps when removing!)
In what cell type would you find Ehrlichia organisms?
Macrophages
What antibiotic class would you want to avoid when treating Mycoplasma or L-form infections?
Beta-lactams (they generally lack a cell wall)
What is the primary clinical sign of borreliosis?
Polyarthropathy
What is the most common species of Staph in food animals?
S. aureus
What Staph organisms are part of the normal skin flora in food animals?
S. aureus
S. hyicus
What is the major MRSA strain associated with swine?
ST398
What exfoliative toxins from S. hyicus are associated with the pathogenesis of greasy pig disease?
Exh A, B, C, D
SHETA
SHETB
Describe the pathogenesis of greasy pig disease
Staph hyicus toxins digest desmoglein-1 –> scale/crust
Is Erysipelothrix rhusiopathiae zoonotic?
Yes
Is Erysipelothrix fast-growing or slow-growing on culture?
Slow-growing
What is the infectious stage of Dermatophilosis congolensis?
Zoospore
Is Dermatophilosis congolensis zoonotic?
Yes (Pruritic/painful pustules or nodules)
What is the causative agent of lumpy jaw in cattle?
Actinomyces bovis
What is the causative agent of “wooden tongue” in cattle?
Actinobacillus lignieresii
At what part of the hair follicle does a dermatophyte stop growing?
Adamson’s fringe
What are the growth requirements for T. verrucosum?
Thiamine
Inositol
What is the cause of “swamp cancer”?
Pythium insidiosum
How are cats infected with cowpox?
Hunting rodents
What papillomaviruses have been associated with equine sarcoids?
BPV-1>BPV-2
What is the causative agent of teat fibropapillomas?
BPV-1
What is the causative agent of head/neck/shoulder fibropapillomas in cattle?
BPV-2
What does Staph protein A bind to?
Fc portion of IgG
Which Lancefield groups of Strep are beta-hemolytic?
A, B, C, G, E, L, M
What is the only Lancefield Group A Strep?
Strep pyogenes
What organism is primarily responsible for fading puppy syndrome?
Strep canis
What Lancefield group is Strep canis part of?
Group G
What are the most commonly zoonotic poxviruses of large animals?
Pseudocowpox (parapoxvirus)
Contagious Viral Pustular Dermatitis (orf)
Bovine papular stomatitis (parapoxvirus)
What organism can mechanically transmit poxvirus?
Stomoxys calcitrans (stable fly)
What is a vector in the spread of swinepox?
Haematopinus suis (swine louse)
What condition is a “horseshoe scab” pathognomonic for in cattle?
Pseudocowpox
What poxvirus has a vaccine that should be given annually?
Orf
What are the typical lesions of Orf?
Proliferative lesions with thick crusts (lips, muzzle, nostrils, eyelids, teats, udders)
Does poxvirus in ruminants require treatment?
No - low mortality and is self-limiting (careful for zoonosis)
What is the causative agent of Valley Fever?
Coccidiodes
What antigen is detected on enzyme immunoassay for Blasto, Coccidioides, and Histoplasma?
galactomannan
What are the virulence factors of Malassezia?
1) Thick cell wall
2) Biofilm
3) Phospholipase A2
4) Production of enzymes (sphingomyelinase, chitin deacetylase)
What receptor expressed by phagocytes selectively recognizes Malassezia but not other fungi?
Mincle – binds glucosyl and mannosyl glycolipids
What receptor expressed by Langerhans cells is a PRR for commensal and pathogenic fungi?
Langerin – recognizes mannose and B-glucan
What cat breeds are predisposed to Malassezia?
Sphynx
Devon Rex
What are fungal cell walls made of?
Chitin
Chitosan
Mannan
Glucan
What should be added to a culture plate for growth of Trichophyton equinum?
Niacin
What antigens are virulence factors for Blastomyces, causing adherence of yeast to host cells?
BAD1
WI-1
What organism causes ringworm in hedgehogs?
Trichophyton erinacei
Which dog breeds have an increased risk of disseminated Coccidiomycosis infection?
Boxers
Dobermans
What occurs in inflamed skin that stimulates Malassezia to produce more phospholipase?
Endogenous opioids (i.e. beta-endorphin)
What antibiotic is recommended for treatment of toxic shock syndrome?
Clindamycin
What causes Mycobacteria to be positive on acid-fast?
High mycolic acid lipid content in their walls
What organisms are most likely to cause black grain mycetomas?
Curvularia geniculata
Madurella
What organism is likely to cause white grain mycetoma?
Pseudallescheria
Acremonium
What is the major strain type for MRSP in the US?
ST68
What is the major strain type for MRSP in Japan and Europe?
ST71
What is essential for antibiotic treatment of Brucella canis?
combine multiple antibiotics (tetracycline + FQ or aminoglycoside + sulfonamide)
How long should dogs in an infected Brucella kennel be tested for after seronegative status is reached?
3 months
Which Brucella species cause disease in people?
B. canis
B. abortus
B. suis
B. melitensis
Why is B. canis less virulent than other Brucella species?
It lacks LPS in cell wall
What cutaneous lesions can be seen with Burkholderia?
Ulcers
Chronic abscesses and SQ granulomas
What is the definition of extensively drug resistant (XDR)?
Susceptibility to <=2 antimicrobial classes
What is the definition of multidrug resistant?
Resistance to >= 2 antimicrobial classes
Where is the most consistent site of Staph carriage in dogs and cats?
Oral cavity
What is the best predictor of pathogenic potential of a Staph strain?
Ability to coagulate plasma
What Staph species are carried most frequently by cats?
S. aureus
S. pseudintermedius
What is the most frequently isolated MRSA strain from pets in the US?
CC22
What genes expressed by Staph pseud confer resistance to tetracyclines?
tet(M)
tet(K)
What tetracycline will Staph be susceptible to if it possesses tet(K) but not tet(M)?
Minocycline
In equine sarcoid, what early genes of the virus possess transforming capability?
E5, 6, 7
In equine sarcoids, what early genes of the virus regulate replication and transcription?
E 1, 2, 4
Which viral genes encode structural proteins in BPV?
late genes (L1, 2)
Which BPV viral genes have been positively correlated with disease severity in equine sarcoids?
E 2, 5, 6, 7
L 1, 2
Which BPV viral genes function as the major oncoproteins that stimulate sarcoid development in horses?
E 2, 5, 6, 7
True or false: BPV DNA has been found in non-sarcoid lesions in horses and in normal equine skin
True
What controls the invasiveness of equine sarcoids?
MMP 1, 2, 3
What horse breeds are predisposed to develop sarcoids?
QH + Franches-Montagnes > TB> SB
What stain could be applied to a slide to highlight Leishmania kinetoplasts?
Giemsa
What is the gold standard for diagnosis of Leishmania?
PCR on bone marrow or LN
