Actinobacillus spp. Flashcards
Which species of Actinobacillus are of major veterinary importance?
A. lignieresii
A. pleuropneumoniae
A. equuli
A. suis
A. seminis
General characteristics of Actinobacillus spp.
gram neg
pleomorphic
facultative anaerobes
non-motile
oxidase pos, urease pos
BA and MAC lactose fermenting - some exceptions
Habitat of Actinobacillus spp.
host specific
mainly pathogens of farm animals
commensals on mucous membranes
cannot survive for a long time in the environment
What bacteria causes wooden tongue in cattle?
Actinobacillus lignieresii
What other species can wooden tongue occur in?
sheep, horses, pigs, dogs
note: rare in chickens
A. lignieresii is a ___ of the oral cavity and intestinal tract
commensal
How long can A. lignieresii survive for in the environment?
up to 5 days in hay and straw`
How does A. lignieresii enter the body to cause infection?
enters through erosions or lacerations in the mucosa or skin
Describe the pathogenesis of A. lignieresii
infect soft tissues and cause cellulitis
develop into abscesses with thick yellow-white pus
spread via lymphatics
Clinical signs of wooden tongue
firm, localized swellings (granulomas) - especially of the tongue
pain, difficulty eating, drooling, tongue protrusion
Diagnosis of wooden tongue
microscopy of pus or exudate: reveal granules, 10% KOH, crush granules - club shaped structures surround bacteria
confirm diagnosis: culture and biopsy of lesion
Differential diagnosis - wooden tongue caused by A. lignieresii
lumpy jaw caused by Actinomyces bovis
neoplasia
Treatment of wooden tongue
systemic antibiotics
sodium iodine (parenterally) - ruminants
potassium iodide (orally)
How to prevent wooden tongue
good quality feeds
avoid coarse feeds
proper pasture management
isolate animals with discharging lesions
What is the causative agent of porcine pleuropneumonia
Actinobacillus pleuropneumoniae
Is A. pleuropneumoniae host specific?
yes - for swine
Describe porcine pleuropneumonia
severe contagious respiratory disease seen worldwide
primarily in young pigs under 6 months old
sudden onset, short course, high morbidity and mortality
How many serotypes of A. pleuropneumoniae are there?
15 serotypes
vary in virulence and significance
How is A. pleuropneumoniae transmitted?
close contact with nasal secretions
opportunistic
gain entry via broken skin
can be spread via fomites
A. pleuropneumoniae virulence factors
capsule
adehesins and fimbriae
iron acquisition factors
cytotoxins and proteases
4 RTX toxins
Disease conditions associated with acute porcine pleuropneumoniae
sudden deaths, high morbitity and mortality
fever
respiratory distress
pneumonia, pleurisy, lungs congested and hemorrhage
blood stained frosth from nostrils or oral cavity
Disease conditions associated with chronic procine pleuropneumonia
chronic cough due to lung lesions
retarded growth
Diagnosis of porcine pleuropneumonia
serologic tests: complement fixation and ELISA
culture and isolation: requires factor V (NAD) for growth
PCR
Does A. pleuropneumoniae grow on MAC?
NO - requires factor V from lysed RBC to grow
What agar does A. pleuropneumoniae grow on?
blood agar pre streaked with S. aureus to provide factor V
chocolate agar
Is CAMP testing used to identify A. pleuropneumoniae?
yes - CAMP test positive
Treatment of porcine pleuropneumoniae
antibiotic treatment is difficult
need immediate parenteral antibiotic tx: ceftiofut, tilmicosin, tetracyclines, synthetic penicillins, tylosin, sulfonamides
followed by oral antibiotic treatment
Prevention of porcine pleuropneumoniae
good husbandry
improved ventilation
proper stocking density
polyvalent bacterins
subunit vaccines containing toxoids and capsular antigen
What diseases are caused by Actinobacillus equuli subsp. equuli
sleepy foal disease (septicemia)
joint ill in horses (purulent arthritis)
septicemia in pigs
What diseases are caused by Actinobacillus equuli subsp. haemolyticus
metritis, abortion, pneumonia, meningitis (in horses)
Describe sleepy foal disease
acute, potentially fatal septicemia in newborn foals
found in the reproductive and intestinal tracts of mares - infecting foals in utero or after birth
Predisposing factors of sleepy foal disease
failure of passive transfer of maternal antibodies
poor sanitation, co-infections
Pathogenesis of A. equuli
exotoxins lyse erythrocytes and lymphocytes
death in 1-2 days
Is it possible for foals to survive and recover from A. equuli infections?
yes - develop microabscesses, polyarthritis, nephritis, enteritis, pneumonia
What is observed postmortem on foals that died from sleepy foal disease?
petechiation on serosal surfaces
enteritis
Viruelnce factors of A. equuli subsp. haemolyticus
RTX toxin
Diagnosis of A. equuli
culture and isolation
sticky colonies on BA
lactose fermenting colonies on MAC
live foals: collect blood
dead foals: fresh biopsies or charcoal swabs from kindeys and lungs
adult horses: primary target organ of disease syndrome
PCR
Treament of A. equuli
gentamicin, chloramphenicol, 3rd gen cephalosporins
supportive care: blood tranfusions and bottle feeding w colostrum
Prevention and control of A. equuli
sanitation and hygeine during foaling
apply antiseptic to umbilicus
remove expelled placenta and soiled bedding soon after foaling
NO vaccines
What animals does Actinobacillus suis typically effect?
mainly piglets less than 3 months of age
can infect pigs of all ages
What disease is caused by A. suis
pleuropneumonia
How is disease caused by A. suis characterized?
septicemia
enteritis
meningitis
metritis
abortion
rapid death
Clinical signs of A. suis in piglets
fever, respiratory distress, prostration and paddling of the forelimbs
petechial and ecchymotic hemorrages in many organs
interstitial pneumonia, pleuritis, arthritis, meningioencephalitis, myocarditis
mortality rate may be up to 50%
Clinical signs of A. suis in older pigs
like those in poglets
lethargy, depression, anorexia
abortion
myocarditis
skin lesions
Differential diagnosis A. suis in older pigs
rule out S. suis, erysipelas, salmonella
Diagnosis of A. suis
postmortem specimen
cultured on BA and MAC for 24-72 hours
BA : sticky, hemolytic colonies
MAC : pink, lactose fermenting colonies
biochemical testine
definitive diagnosis: 16s rRNA sequencing
Treatment of A. suis
susceptibility testing: ampicillin, carbenicillin, potentiated sulphonamides and tetracyclines
Control and prevention of A. suis
disinfection
NO vaccines
Actinobacillus seminis causes what disease?
epididymitis in young rams
Where is A. seminis endemic
New Zealand, Australia, South Africa, USA, UK
Is A. seminis part of the normal flora?
yes - found in the prepuce
ewe may be an intermediate carrier
Disease conditions associated with A. seminis
spermatic granulomas
abscesses form in epididymidis
purulent discharge on the scrotal skin
At what age are rams most affected by A. seminis infections?
rams 4-8 months of age
Diagnosis of A. seminis
pus, biopsy material
culture on BA and MAC for 24-72 hours
BA : small, pin-point, non-hemolytic colonies
NO growth on MAC
catalase pos
unreactive on many biochemical tests
PCR
CFT
ELISA
Treatment and control of A. seminis
NO vaccine
recovered rams show reeduced fertilitiy
prophylactic antibiotics
