Infectious Disease Flashcards
Most common Aspergillus spp. causing SNA in dogs?
A. fumigatus
Most common Aspergillus spp. causing disseminated aspergillosis in dogs?
A. terreus or A. deflectus
% of dogs in which SNA requires trephination/sinus assessmen to allow for diagnosis?
17%
Methods of detecting fngal hyphae in SNA and success rate of these methods?
Nasal dishcarge/swabs: 13 - 20% cases
Brushing/Squash preparations of plaques: 93 - 100%
Sites for fungal culture and sensitivity for diagnosis of SNA
Fungal plaques: 88%
Mucosa: 75%
Nasal swabs: 19%
Best serological test for aspergilluis and its sensitivity and specificty
ELISA (rather than AGID)
Sensitivity 88.2% and specificity 96.8%
What property of topical antifnugals should be considerd wen treating SNA?
Use a PEG based solution as these have less severe local ide effects
What advantage does enilconazole have over clotrimazole for the treatment of SNA?
It is less toxic and is active in a vapour phase up to 1cm distances
What is the reccomended mode of treatment in canine SNA?
Endoscopic debridement of the nasal cavities, follwed by 1hinfusion of 1% clotrimazole cream through blindly placed catheters into the nasalcavities/sinus.
Although this is just the ettinger discussion as other methods have similar results
What is the best way of determining therapeutic efficacy following SNA treatment?
a) CT re-evaluation
b) Monitoring of ELISA
c) Repeat culture
d) Repeat endoscopic re-evaluation
Technicaly d perfomed within 1 month of treatment
Overally first treatment success, number of treatments and overall success rate for SNA
60%, 2 treatments, 92%
What option may be considered for very difficult to treat SNA cases?
Oral antifungals
Surgical debridement
What percentage of dogs wwith SNA may have persistet URT signs after treatment?
≥52%
Which beed is predispsed to diseminated aspergillosis?
GSD
What Csx are reported for canine systemic aspergillosis
Spinal pain +/- paraparesis, bone pain, anorexia, weight loss, lethargy, muscle wasting and fever. Pulmonary and ocular involvemet are possible.
What is the diagnostic standard for disseminated canine aspergillosis?
Culture of organism and visualisation of hyphae
Treatment options for pneuocystosis (4 in order of efficacy/preference)
TMPS
Pentamidine isethionate
Atovaqoune
Clindamycin combined with primaquine
Consider anti-inflammatory doses of corticosteroids in severely affected dogs
What are the characteristics of mycobacterial infections:
a) aerobic vs. anaerobic
b) Gram staining
c) Acid fastness
Aerobic gram positive acid-fast organsism.
What are the main organisms in the canine and feline mycobacterium complexes?
What are the main reservoirs of the following mycobacteria:
a) M. tuberculosis
b) M. bovis
c) M. microti
a) humans
b) cattle
c) Field voles
What are the main routes of infection of mycobacteria?
Skin gastrointestinal and respiratory tracts
Methods of diagnosis of mycobacterial infections
Histopathology with demonstration of acid-fast organisms
Culture (takes 4 - 6 weeks)
PCR possible
Treatment of mycobacteria
- Excision and debridement of cutaneous lesions
- 2 months with rifampicin AND a fluroquinolone or macrolide (ideally pradofloxacin or moxifloxacin) AND clarithromycin/erythromycin
- Addtional 4 - 6 months of rifampicin and either fluroquinolone or macrolide
What is the epidemiologic difference between saprophytic and tuberculoid mycobacterium?
Saprophytic organisms live in the soil and are categorised as slow growing (e.g. M avium) and fast growing.
What is the difference in presentation between slow growing and fast growing saprophystic mycobacterium?
Slow growing cause a more classical tuberculoid disease
Fast growing cause more of a diffuse disease which has a predilection for adipose tissue –> panniculitis.
What is the treatment for granulomatous panniculitis in cats?
Gentamycin
What stain can be used for leperiod mycobacterial species?
Kinyuon-modified Ziehl-Neelson
How can actinomyces and nocardia be distinguished cytologically?
Both are gram positive filamentous rods.
Actinomyces is non-acid fast
Nocardia is variably acid fast
Where is actinomyces normally found?
In the oral cavity
What disease presentation is expected with actinomyces and nocardia?
Pyogranulomatous (dogs) or pyothorax (cats)
How is actinomyces diagnosed?
Kinyuon-modified Ziehl-Neelson staining (non-acid fast organisms)
Culture
16sRNA PCR
Treatment options for actinomyces
- Penicillins
- Clindamycin/erythromycin
- Chloramphenicol
Where is nocardia normally found?
Soil
Diagnosis of nocardia
Cytology
Culture
16sRNA PCR
Treatment of nocarida
- TMPS
- Amikacin
- Imipenem-cilastin
- Cefotaxime
What type of bacterium is brucella canis?
Gram negative coccobacillus
What is the pathogenesis (i.e. transmission routes, dissemination and predilection) for Brucella?
Main clinical signs of Brucellosis
Abortion and Infertility
Lymphadenopathy
Epididymitis and orchitis
Discospondyltitis
Granulomatous disease
What stages following suspected exposure to Brucella canis can serologic testing be performed?
4 weeks after infection and can be repeated if you are testing within 12 weeks of cliincal signs.
Diagnostic test procedure for Brucella canis
- Perform RSAT (which is sensitive but not specific)
- Positive RSAT should promt repeat RSAT wiht 2-mercaptoethanol added
- AGID is performed to confirm a positive ME-RSAT
- Tube agglutination test can also be performed folowing ME-RSAT
PCR is useful for aborted material
What is the treatment for Brucella canis
Enrofloxacin
What type of bacteria is Bartonella?
Gram negative facultatively intracellular
What is the main vector for Bartonella and what other species have been implicated?
Ctenocephalides felis
Pulex fleas
Ixodes
Rhipicephalus sanguineus
What are the most common Bartonella spp. in the dog and cat
Dog = B. henselae and B. vinsonii subspp. berkoffi
Cat = B. henselae and B. clarridgae
What are the reservoirs for the following Bartonella spp.
a) B. henselae
b) B. vinsonii subspp. berkoffi
c) B. clarridgae
a) Cats
b) Dogs, Coyotes
c) humans and dogs
Where is seroprevalence highest for canine Bartonellosis?
Northeast, Midatlantic and southern states
What is the most common consequence of canine Bartonellosis?
Endocarditis
Which Bartonella spp. is most commonly associated with canine endocarditis. How does Bartonella differ to the presentation of other forms of IE?
B. vinsonii
In contrast to most caues of IE, Bartonela typically affects the aortic valve, they are also more likely to have CHF and more likely to die with IE compared to other causes
What are the most common laboratory abnormalities identified in Bartonella infection?
Proteinuria
Anaemia
Leukocytosis
Thrombocytosis
When, in Bartonella infection, are PCR and serology potentially appropriate?
With endocarditis PCR on blood is more likely to be positive but is otherwise insentitive due to intermittent bacteraemia. Serology titres > 1:512 can be useful in cases of endocarditis. Otherwise diagnosis with BAPGM + PCR is good.
How should canine Bartonella be treated?
Start an antibiotic and then a second 5 - 7 days later to avoid the chance of a jarisch herxheimer reaction.
Treatment:
- Doxcycline + enrofloxacin, rifampicin or amikacin
- Azithromycin and rifampicin
What are the possible manifestations of felinbe Bartonellosis?
Localised skin abscessation
Lymphadenopathy
Pyrexia
Neurologic or reproductive signs
In feline Bartonellosis, when is oral disease more likely?
If the cat is concurrently infected with FIV
What are the main treatment choices for feline Bartonellosis?
Doxycylcine, pradofloxacin, enrofloxacin
How is leptospirosis differentiated from other spirochete organisms?
Hooked tail
How do animals become infected with leptospirosis?
Through contact with contaminated soil, urine or water. The bacteria can enter the body either through mucous membranes or broken skin.
When is leptospirosis most likely to occur?
In warmer months following flooding or heavy rainfall
What are the main three clinical consequences of leptospirosis
Renal disease (acute interstitial nephritis due to dysfunction of Na/KATPase)
Hepatic disease
Leptospiral pulmonary haemorrhage syndrome
How should MAT for leptospirosis be performed?
Paired samples should be taken 1 - 2 weeks apart
How should leptospirosis be treated?
With penicillins during the acute phase and doxycycline for 14 days to clear renal shedding.
How should dogs in a household that have had exposure to a dog with leptospirosis be managed?
Ideally should be treated with 14 days of doxyxycline and monitored with MAT
What type of bacteria are the rickettsial species? (e..g E. canis, anaplsam, RMSF etc.)
Gram negative intracellular bacteria
What is the vector for E. canis?
Rhipicephalus sanguineus
What would Ehrlichia canis look like on cytology of a blood smear?
One would see a morulae within monocytes
What are the potential clinical consequences of E. canis infection?
Infection can be acute, subclinical or chronic.
Acute disease is characterised by non-specific signs of fever, lethargy and lymphadenopathy although neurologic signs are also possible. Thrombocytopenia can also occur.
In the chronic phase a pancytopenia, bleeding tendancies, monoclonal gammopathy and PLN due to IGCN can occur
Where is E. canis sequestered in the subclinical phase of infection
Spleen
At what stage of infection can E. canis antibodies be detected by ELISA?
7 - 28 days post-infection
What is the diagnostic utility of PCR in E. canis infection?
Low sensitivity
Treatment options for E. canis
- Doxycycline for 28 days
- Chrloramphenicol
- Imidocarb
Fluroquinolones are not reccomended due to the potential for intrinsic resistance
What is the reservoir for E. canis?
Wild dogs
What is the vector and reservoir for Ehrlichia ewingii/ E. chaffiensis?
Vector = amblyoma americanum
Reservoir = white tailed deer
How does the cytologic diagnosis of E. canis vs. E. ewingii/chaffiensis differ?
In E. canis the morular are within monocytes, in the others they are within granulocytes
How is E. chaffiensis/ewingii treated?
Same as E canis
- Doxycycline for 28 days
- Chrloramphenicol
- Imidocarb
What is the vector and reservoir for anaplasma phagocytophilum?
Ixodes spp.
Reservoir = small mammals
What co-infection should be considered in dogs with anaplasma phagocytophilum?
Borrelia
What is the cytologic appearance of anaplasma phagocytophilum in a blood smear?
Morulae will be present within neutrophils and eosinophils (so similar to E chaffiensis/ewingii)
How does the clinical course of disease with anaplasma phagocytophilum differ in dogs compared to Ehrlichial disease?
They do not have a chronic phase of infection so all the signs are acute.
How is the serologic diagnosis of anaplasma phagocytophilum different to Ehrlicial disease?
There is a longer incubation period for A. phagocytophilum (1 - 2 weeks) so could get a false negative. Therefore, demonstration of convalescent titres may be required.
What is the vector for anaplasma platys?
Rhipicephalus sanguineus