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LA DX & TX II > Exam 2 - Corynebacterium > Flashcards

Exam 2 - Corynebacterium Flashcards

1
Q

what species can be infected by corynebacterium pseudotuberculosis?

A

disease of sheep/goats

any horse!!!!

cattle, camelids, swine, wild ruminants, fowl, & humans

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2
Q

is corynebacterium pseudotuberculosis zoonotic?

A

yup

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3
Q

how would you define the term ‘saprophytic’ as it relates to corynebacterium?

A

long term persistence in soil, > 55 days!

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4
Q

when are outbreaks of pigeon fever seen most commonly in texas? why?

A

summer & fall - peak incidence

because it is dry & there are insects everywhere (house fly, stable fly, & horn fly)

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5
Q

what are 2 major environmental risk factors associated with pigeon fever infection?

A

outbreaks seen after periods of:

  1. drought
  2. high environmental temperatures
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6
Q

what are the 3 clinical presentations/forms seen in horses with pigeon fever? of these 3 forms, which one has the best prognosis for survival?

A
  1. external
  2. internal
  3. ulcerative lymphangitis

external has the best prognosis

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7
Q

how did pigeon fever get its name?

A

swelling that occurs on the pectorals looks like a pigeon breast

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8
Q

what is the most common clinical sign appreciated with the internal form of pigeon fever?

A

internal abscesses!!!!! weight loss & colic are common clinical signs

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9
Q

which diagnostic test is most useful for diagnosing the internal form of pigeon fever? how does this test work & why is it less useful for the external forms?

A

SHI test - PLD & r. equi are synergistic, so it detects antibodies to phospholipase D exotoxins

better tests available for external forms such as culture

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10
Q

what are the similarities & differences of corynebacterium in regards to biovar between horses & goats/sheep?

A

horses: biovar equi

goats/sheep: biovar ovis

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11
Q

what are the similarities & differences of corynebacterium in regards to transmission between horses & goats/sheep?

A

horses: we don’t really know, but we think through abrasions/bug bites

goats/sheep: come into contact with draining purulent material in their environment & some sort of wound allows organism access across skin/mucus membranes

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12
Q

what are the similarities & differences of corynebacterium in regards to clinical signs between horses & goats/sheep?

A

horses: 3 forms, clinical signs dependent on form

goats/sheep: external & internal form, external most common, internal, think nasty lung abscesses

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13
Q

what are the similarities & differences of corynebacterium in regards to diagnosis between horses & goats/sheep?

A

horses: clinical signs, history, c/s, u/s, SHI test

goats/sheep: clinical signs & culture, past history

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14
Q

what are the similarities & differences of corynebacterium in regards to treatment between horses & goats/sheep?

A

horses: dependent on form, but lance/drain, abx, & supportive care

goats/sheep: get rid of them! or treat them if their people love them a lot and isolate them from the rest of their buddies

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15
Q

what are the similarities & differences of corynebacterium in regards to prognosis between horses & goats/sheep?

A

horses: better prognosis with external form, worst prognosis with ulcerative lymphangitis

goats/sheep: not curable, hard to eradicate within the herd, disease won’t necessarily kill them but the veterinarian will

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16
Q

what are the similarities & differences of corynebacterium in regards to prevention/control between horses & goats/sheep?

A

horses: environmental management is primary intervention

goats/sheep: prevent bringing in infected animals, cull positive animals, better environmental management, safer practices using needles/shears

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17
Q

what would be a reasonable control program within a herd of small ruminants experiencing cases of CL?

A

cull all positive animals!!!!

if wanting to treat, can try draining lesions as much as possible & using oxytet/tulathromycin

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18
Q

dryland distemper is another name for what?

A

pigeon fever

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19
Q

what is the cell morphology/characteristics of pigeon fever in horses?

A

gram positive intracellular facultate anaerobe

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20
Q

how is pigeon fever spread in horses?

A

unknown - we think through abrasions, insects, lymphatics, & hematogenous spread

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21
Q

T/F: pigeon fever in horses is more common in arid, western states such as texas

A

true

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22
Q

what is the incubation period of pigeon fever in horses?

A

3-4 weeks, long

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23
Q

when is the peak incidence of pigeon fever everywhere else outside of the southwest US?

A

fall & winter - dry times with insects

24
Q

what is the most common form of pigeon fever we see in horses? what is the prognosis?

A

external

best prognosis

25
Q

what clinical signs are seen in horses with the external form of pigeon fever?

A

external abscesses - pectorals, inguinal, vaginal & facial panniculitis

26
Q

in order from best prognosis to worst prognosis, rank the different forms of pigeon fever in horses

A

external > internal > ulcerative lymphangitis

27
Q

what clinical signs are seen in horses with the internal form of pigeon fever? what is the mortality rate?

A

internal abscesses - pulmonic, mediastinal, pericardial, hepatic, splenic, mesenteric, & renal

weight loss & colic are common

organ associated clinical signs

30-40% mortality

28
Q

what clinical signs are seen in the ulcerative lymphangitis form of pigeon fever?

A

small abscesses & ulcers that develop along lymphatic vessels

extremely painful - cellulitis, lameness, sloughing, lethargy, fever, & anorexia

29
Q

why does ulcerative lymphangitis have a poor to guarded prognosis?

A

you must be super aggressive with your treatment - worries about laminitis

30
Q

how is pigeon fever diagnosed in horses?

A

SHI test

exotoxins - phospholipase D, degrades sphingomyelin causing pain & inflammation

phospholipase D & r. equi are synergistic, so they will lyse RBC in agar & detect IgG, most useful for internal abscesses without concurrent external abscesses

culture & PCR

ultrasound

31
Q

what treatment is done for horses with the external form of pigeon fever?

A

lance & drain abscesses

32
Q

what treatment is done for horses with the internal form of pigeon fever?

A

aggressive abx - enro, chloramphenicol, & tetracyclines

hydrotherapy, anti-inflammatories, support bandages, & supportive care

33
Q

why do we care about pigeon fever in horses?

A

it can affect any horse, concerns about changes in the environment (ubiquitous in the environment & insect populations)

outbreaks have a high morbidity & carry a variable prognosis, big economic impact

34
Q

how is environmental management utilized for preventing pigeon fever in horses?

A

climate change, fly control, insect prevention, & biosecurity

can’t clean the soil

35
Q

T/F: horses develop some level of immunity after natural infection & recovery

A

true

36
Q

is there a vaccine for pigeon fever? is it used?

A

there was an autogenous bacterin-toxoid that induced a host immune response, but it is not recommended anymore & only existed briefly

37
Q

what are the virulence factors of corynebacterium pseudotuberculosis?

A

lipid coated - protects it from enzymes within host phagocytes

phospholipase d - exotoxin

38
Q

what is the pathogenesis of caseous lymphadenitis in small ruminants?

A

draining lesions or aerosol spread through the rupture of lung abscesses - most common is contact with purulent draining material

needs access across the skin/mucus membranes - shearing of sheep, needles, or skin trauma

carried to regional lymph nodes where it establishes an infection (external form in both goats & sheep) or goes to internal organs (internal form, sheep > goats)

bacteria replicates inside of host phagocytes, ruptures, releases, & repeats which leads to the characteristic layering of purulent material & caseous consistency

39
Q

why do we not like to drain abscesses of CL in sheep/goats?

A

hazardous - very hardy organism in the environment that can last 2 to 8 months with the right protection

40
Q

what clinical signs are seen in the external form of CL in sheep/goats?

A

abscessation in region of lymph nodes - parotid, submandibular, prefemoral, inguinal, & occasionally ectopic

41
Q

what clinical signs are seen in the internal form of CL in sheep/goats?

A

weight loss despite a good appetite - ‘thin ewe syndrome’

depends on organ involvement

cough & purulent nasal discharge

42
Q

how is CL diagnosed in sheep/goats?

A

culture is definitive

maybe SHI test?

43
Q

T/F: there are no consistently efficacious treatments for CL in sheep/goats

A

true

44
Q

what is the goal of treatment of CL in sheep/goats?

A

want to get the lesions to resolve & have no recurrence

45
Q

what do we currently use today to treat CL in sheep/goats?

A

attempt to remove as much purulent material from the lesion as possible - aspirate & flushing

instill 20mg/kg dose of oxytet into the lesion & 2.5mg/kg tulathromycin SQ & repeat if necessary in 1-2 weeks

46
Q

what is important to consider in treating sheep/goats with CL and using oxytetracycline & tulathromycin?

A

extralabel use of both drugs - withdrawal time is 38 days after their last dose of tulathromycin

47
Q

is there a vaccine used for preventing CL in sheep/goats? is it recommended?

A

yes - approved vaccine available for sheep/goats

not recommended

48
Q

how is CL prevented in sheep/goats?

A

remove these animals from your herd!!!!!

screen any new arrivals

49
Q

T/F: for CL in sheep/goats, the organism isn’t always cleared completely even if the lesions appear to resolve

A

true

50
Q

T/F: in positive CL sheep/goats, CULL THEM

A

true

51
Q

what is the hallmark clinical finding of external CL in sheep/goats?

A

development of abscesses in the region of external lymph nodes - submandibular, parotid, prescapular, & prefemoral

52
Q

what is the difference in abscess material between sheep & goats with external CL?

A

goats - soft pasty material

sheep - thick & caseous

53
Q

what is wrong with this goat?

A

caseous lymphadenitis - cull it

54
Q

what is the only way to definitively diagnose CL in sheep/goats?

A

culture of purulent material from an intact abscess

use ultrasound for internal abscesses

55
Q

how does a SHI test work?

A

synergistic hemolysin inhibition test - detects antibodies to phospholipase D exotoxin

positive titers are indicative of: past resolved infections, recent exposure, recent vaccination, active lesions, or lesion development

LA DX & TX II (44 decks)

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