Exam 2 - Corynebacterium Flashcards
what species can be infected by corynebacterium pseudotuberculosis?
disease of sheep/goats
any horse!!!!
cattle, camelids, swine, wild ruminants, fowl, & humans
is corynebacterium pseudotuberculosis zoonotic?
yup
how would you define the term ‘saprophytic’ as it relates to corynebacterium?
long term persistence in soil, > 55 days!
when are outbreaks of pigeon fever seen most commonly in texas? why?
summer & fall - peak incidence
because it is dry & there are insects everywhere (house fly, stable fly, & horn fly)
what are 2 major environmental risk factors associated with pigeon fever infection?
outbreaks seen after periods of:
- drought
- high environmental temperatures
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?
- external
- internal
- ulcerative lymphangitis
external has the best prognosis
how did pigeon fever get its name?
swelling that occurs on the pectorals looks like a pigeon breast
what is the most common clinical sign appreciated with the internal form of pigeon fever?
internal abscesses!!!!! weight loss & colic are common clinical signs
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?
SHI test - PLD & r. equi are synergistic, so it detects antibodies to phospholipase D exotoxins
better tests available for external forms such as culture
what are the similarities & differences of corynebacterium in regards to biovar between horses & goats/sheep?
horses: biovar equi
goats/sheep: biovar ovis
what are the similarities & differences of corynebacterium in regards to transmission between horses & goats/sheep?
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
what are the similarities & differences of corynebacterium in regards to clinical signs between horses & goats/sheep?
horses: 3 forms, clinical signs dependent on form
goats/sheep: external & internal form, external most common, internal, think nasty lung abscesses
what are the similarities & differences of corynebacterium in regards to diagnosis between horses & goats/sheep?
horses: clinical signs, history, c/s, u/s, SHI test
goats/sheep: clinical signs & culture, past history
what are the similarities & differences of corynebacterium in regards to treatment between horses & goats/sheep?
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
what are the similarities & differences of corynebacterium in regards to prognosis between horses & goats/sheep?
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
what are the similarities & differences of corynebacterium in regards to prevention/control between horses & goats/sheep?
horses: environmental management is primary intervention
goats/sheep: prevent bringing in infected animals, cull positive animals, better environmental management, safer practices using needles/shears
what would be a reasonable control program within a herd of small ruminants experiencing cases of CL?
cull all positive animals!!!!
if wanting to treat, can try draining lesions as much as possible & using oxytet/tulathromycin
dryland distemper is another name for what?
pigeon fever
what is the cell morphology/characteristics of pigeon fever in horses?
gram positive intracellular facultate anaerobe
how is pigeon fever spread in horses?
unknown - we think through abrasions, insects, lymphatics, & hematogenous spread
T/F: pigeon fever in horses is more common in arid, western states such as texas
true
what is the incubation period of pigeon fever in horses?
3-4 weeks, long
when is the peak incidence of pigeon fever everywhere else outside of the southwest US?
fall & winter - dry times with insects
what is the most common form of pigeon fever we see in horses? what is the prognosis?
external
best prognosis
what clinical signs are seen in horses with the external form of pigeon fever?
external abscesses - pectorals, inguinal, vaginal & facial panniculitis
in order from best prognosis to worst prognosis, rank the different forms of pigeon fever in horses
external > internal > ulcerative lymphangitis
what clinical signs are seen in horses with the internal form of pigeon fever? what is the mortality rate?
internal abscesses - pulmonic, mediastinal, pericardial, hepatic, splenic, mesenteric, & renal
weight loss & colic are common
organ associated clinical signs
30-40% mortality
what clinical signs are seen in the ulcerative lymphangitis form of pigeon fever?
small abscesses & ulcers that develop along lymphatic vessels
extremely painful - cellulitis, lameness, sloughing, lethargy, fever, & anorexia
why does ulcerative lymphangitis have a poor to guarded prognosis?
you must be super aggressive with your treatment - worries about laminitis
how is pigeon fever diagnosed in horses?
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
what treatment is done for horses with the external form of pigeon fever?
lance & drain abscesses
what treatment is done for horses with the internal form of pigeon fever?
aggressive abx - enro, chloramphenicol, & tetracyclines
hydrotherapy, anti-inflammatories, support bandages, & supportive care
why do we care about pigeon fever in horses?
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
how is environmental management utilized for preventing pigeon fever in horses?
climate change, fly control, insect prevention, & biosecurity
can’t clean the soil
T/F: horses develop some level of immunity after natural infection & recovery
true
is there a vaccine for pigeon fever? is it used?
there was an autogenous bacterin-toxoid that induced a host immune response, but it is not recommended anymore & only existed briefly
what are the virulence factors of corynebacterium pseudotuberculosis?
lipid coated - protects it from enzymes within host phagocytes
phospholipase d - exotoxin
what is the pathogenesis of caseous lymphadenitis in small ruminants?
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
why do we not like to drain abscesses of CL in sheep/goats?
hazardous - very hardy organism in the environment that can last 2 to 8 months with the right protection
what clinical signs are seen in the external form of CL in sheep/goats?
abscessation in region of lymph nodes - parotid, submandibular, prefemoral, inguinal, & occasionally ectopic
what clinical signs are seen in the internal form of CL in sheep/goats?
weight loss despite a good appetite - ‘thin ewe syndrome’
depends on organ involvement
cough & purulent nasal discharge
how is CL diagnosed in sheep/goats?
culture is definitive
maybe SHI test?
T/F: there are no consistently efficacious treatments for CL in sheep/goats
true
what is the goal of treatment of CL in sheep/goats?
want to get the lesions to resolve & have no recurrence
what do we currently use today to treat CL in sheep/goats?
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
what is important to consider in treating sheep/goats with CL and using oxytetracycline & tulathromycin?
extralabel use of both drugs - withdrawal time is 38 days after their last dose of tulathromycin
is there a vaccine used for preventing CL in sheep/goats? is it recommended?
yes - approved vaccine available for sheep/goats
not recommended
how is CL prevented in sheep/goats?
remove these animals from your herd!!!!!
screen any new arrivals
T/F: for CL in sheep/goats, the organism isn’t always cleared completely even if the lesions appear to resolve
true
T/F: in positive CL sheep/goats, CULL THEM
true
what is the hallmark clinical finding of external CL in sheep/goats?
development of abscesses in the region of external lymph nodes - submandibular, parotid, prescapular, & prefemoral
what is the difference in abscess material between sheep & goats with external CL?
goats - soft pasty material
sheep - thick & caseous
what is wrong with this goat?
caseous lymphadenitis - cull it
what is the only way to definitively diagnose CL in sheep/goats?
culture of purulent material from an intact abscess
use ultrasound for internal abscesses
how does a SHI test work?
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
