Microbiology Flashcards
(27 cards)
(T/F) Corynebacterium pseudotuberculosis is the only bacteria that causes caseous abscesses.
(F)
(T/F) You need an anaerobic culture to diagnose Corynebacterium pseudotuberculosis.
(F, aerobic since it is a gram positive aerobe, also don’t need susceptibility testing bc do not tx with systemic abx)
What is the optimal way to collect a caseous lymphadenitis sample for culture?
(FNA with sterile prep with a large gauge, long needle; lance and draining = environmental contamination)
What are the routes of infection for C. pseudotuberculosis?
(Through broken skin, inhalation, or ingestion; maybe flies as mechanical vector)
If a small ruminant had internal C. pseudotuberculosis abscesses, what are the possible outward signs?
(Wasting/weight loss)
(T/F) Animals vaccinated against C. pseudotuberculosis will always be serologically positive.
(T)
Why is C. pseudotuberculosis treatment difficult?
(Abscesses have a fibrous capsule and the bacteria are intracellular)
What are the pros and cons of a Salmonella PCR?
(Pros → rapid results; Cons → cost, may be less sensitive, no susceptibility info)
What are the pros and cons of a Salmonella culture?
(Pros → less expensive, may be more sensitive, can perform susceptibility testing; Cons → can take more time)
(T/F) Antimicrobial treatment of Salmonella colitis does not decrease Salmonella shedding nor change the course of colitis.
(T, and abx treatment in humans with salmonella has been shown to prolong fecal shedding; but antimicrobial treatment may decrease the risk of septicemia)
What is the primary route of transmission for Salmonella?
(Fecal-oral)
How do patients become carriers of Salmonella?
(Salmonella is facultative intracellular → can infect and persist in macrophages)
(T/F) Colic is a risk factor for Salmonella shedding.
(T, so should isolate horses after a significant colic episode)
What are the three testing options for Johne’s disease?
(ELISA, culture, and PCR)
What are the pros and cons of Johne’s PCR?
(Pros → rapid results, high sensitivity; cons → cost (only costs a bit more than culture), slightly lower sensitivity (?))
What are the pros and cons of Johne’s culture?
(Pros → less expensive (not by much), high sensitivity; Cons → Takes months and normal flora overgrowth can lead to false negatives)
Is the sensitivity or the specificity low for the Johne’s ELISA test?
(Sensitivity i.e. there are lots of false negatives; has really good specificity tho)
When are animals typically infected with Johne’s?
(At or shortly after birth via milk or feces but adult infections can occur as well, clinical signs do not develop for years)
What test is performed on renal biopsy tissue when attempting to confirm an FIP diagnosis?
(IHC)
What are the cons of the Rivalta POC test for FIP?
(Not all FIP + cats will be positive and other causes of effusion can lead to a false positive)
What are the cons of serological testing for FIP?
(Many cats are seropositive, you cannot differentiate b/w response to coronavirus and FIP nutant, and false negatives are possible)
(T/F) PCR testing of abdominal fluid cannot distinguish between feline coronavirus and feline infectious peritonitis mutant.
(T)
What is the issue with PCR testing fecal material for FIP?
(Lots of healthy cats shed feline coronavirus in their feces, doesn’t mean they have FIP)
What determines if a cat gets FIP?
(They have an enteric infection with feline coronavirus, that feline coronavirus mutations to have a macrophage tropism, and they have a lack of a strong cell mediated immune response to the mutated virus; only then will they develop FIP)
