Infectious Diseases - Sykes & Ettinger

Question 1

Answer 1

Morula in a mononuclear cell –> Ehrlichia canis or chaffeensis, Neorickettsia risticii

Question 2

Organism? Size? Type? Magnification?

Answer 2

Blastomyces dermatitidis

5-20 microns (big)

Extracellular budding yeast

20-50x

Question 3

Organism? Size? Form in the body? Magnification?

Answer 3

Cryptococcus neoformans-gatii complex

3.5-7 microns (small)

Extracellular yeast

100x

Question 4

Organism? Size? Form in the body? Magnification?

Answer 4

Coccidiodes immitis or posadacii

20-200 microns (big)

Extracellular spherules containing numerous endospores

40x

Question 5

Organism? Size? Form in the body? Magnification?

Answer 5

Histoplasma capsulatum

2-4 microns

Intracellular yeast in mononuclear phagocytes

100x

Question 6

Organism? Size? Form in the body? Magnification?

Answer 6

Sporothrix schenckii

2-3 x 3-6 microns (ovoid)

Intracellular yeast in mononuclear phagocytes

100x

Question 7

Possible organisms?

Answer 7

Morula in a neutrophil –> Ehrlichia ewingii, Anaplasma phagocytophilum

Question 8

Organism?

Answer 8

Canine distemper virus

Inclusions in lymphocytes, neutrophils, RBCs

Question 9

What vaccines are considered core vaccines in puppies?

What is the recommended vaccination schedule?

Answer 9

Parvo, distemper, adenovirus, rabies

every 3-4 weeks starting at 8-9 weeks of age

last dose given at > 16 weeks

Question 10

What vaccines are considered core vaccines in kittens?

Recommended vaccination schedule?

Answer 10

Panleukopenia, feline herpesvirus-1, feline calicivirus

Every 3-4 weeks starting at 8-9 weeks of age, last given at > 16 weeks

Question 11

What three enteric zoonoses are immediately infectious after shedding in animal feces?

Answer 11

Campylobacter, Cryptosporidium, Giardia

Question 12

What zoonotic infections are associated with visceral larva migrans in humans?

Answer 12

Toxocara cati, Toxocara canis (roundworms), Baylisascaris procyonis

Question 13

Class and mechanism of action of fenbendazole?

Susceptible organisms?

Answer 13

Benzimidazole class

Bind beta tubulin –> inhibition of microtubule formation & cell division

Inhibition of glucose uptake by protozoa, helminths

Organisms: Giardia, Taenia tapeworms

Roundworms (Toxocara canis & cati, Toxascaris leonina)

Hookworms (Ancylostoma caninum, tubaeforme, braziliense, Uncinaria stenocephala)

Whipworms (Trichuris vulpis)

Question 14

Mechanism of anti-protozoal effect of nitroimidazoles?

Drugs in the nitroimidazole class?

Susceptible parasites?

Answer 14

Mechanism: metabolized by protozoal nitroreductase to reactive oxygen species

Drugs: metronidazole, ronidazole, benznidazole

Metro –> Giardia protozoa

Ronidazole –> Tritrichomonas blagburni (prev foetus)

Benznidazole –> T. cruzi

Question 15

What bacterial genus is inherently resistant to TMS?

Answer 15

Enterococcus spp

Question 16

Mechanism of action of pyrimethamine?

What other antimicrobial works similarly?

Susceptible organisms?

Answer 16

Dihydrofolate reductase inhibition –> lack of folate synthesis

Sulfa drugs also inhibit dihydrofolate reductase, but are more specific to bacterial forms

Organisms: Toxo, Neospora, Isospora (intestinal coccidiosis)

Hepatozoon americanum (in combo with TMS and clinda)

Question 17

Mechanism of action of atovaquone?

Susceptible organisms?

Answer 17

Inhibition of cytochrome bc1 complex –> inhibition of mitochondrial electron transport

Babesia gibsoni and condradae, cytauxzoon felis (in combination with azithromycin)

Question 18

Mechanism of action of imidocarb diproprionate?

Susceptible organisms?

Answer 18

Inhibition of protozoal DNA synthesis

Babesia canis, Hepatozoon canis (not described in the US)

Question 19

Mechanism of action of amphotericin B?

Azole drugs?

Terbinafine?

Which drugs have good CNS penetration? Concentration in the urine?

Answer 19

Amphotericin B: irreversible binding of sterols in fungal cell membranes, forming pores/channels with leakage of ions; also activates macrophages & enhances macrophage killing mechanisms

Azoles: Inhibition of sterol 14-alpha demethylase –> inhibit ergosterol synthesis, cause buildup of 14alpha methylsterols which disrupt fungal cell membrane

Terbinafine: inhibits squalene epoxidase -> decreased lanosterol & ergosterol synthesis & buildup of toxic squalene

Itraconazole. fluconazole have good CNS penetration; flu has good concentration in urine

Question 20

Recommended treatment for canine Leishmaniasis?

What drug is NOT recommended?

Answer 20

Antimony: converted from pentavalent to toxic trivalent form & interferes with DNA synthesis in the parasite

Allopurinol: purine analog; metabolites incorporated into RNA –> impaired protein synthesis USE IN COMBO W/ ANTIMONIAL COMPOUND

Amphotericin B has activity, but not recommended due to increasing resistance

Question 21

Sensitivity and specificity of the SNAP 4Dx ELISA for ehrlichiosis, and anaplasmosis?

Answer 21

Ehrlichia: 97% sensitive, 100% specific (doesn’t do species) (Ettinger says high 90s for both species for sens & spec)

Anaplasma: 92% sensitive, 100% specific (doesn’t do species)

Question 22

Most common viral pathogen associated with CIRD? 2nd most? Characteristics?

Answer 22

Canine parainfluenza virus: enveloped ssRNA Paramyxoviridae

-often co-infected w/ Bordetella (G- aerobic coccobacillus)

Canine respiratory coronavirus: enveloped ssRNA Coronaviridae