Week 5

• Actinobacillus spp.

  gram negative coccobacilli

  facultative anaerobic

  fastidious, capnophilic

  non-motile, non-spore forming

  some grow in MacConkey
• Actinobacillus spp. ecological characteristics

  worldwide distribution

  limited host range

  transmission - aerosol or close contact

  commensals of mucosa of upper respiratory tract and oral cavity

  disease afre associated with endogenous sources (except foals)
• Actinobacillus virulence factors

  RTX toxins - hemolytic and leukocytic

  biofilm

  LPS

  transferrin-binding proteins - iron acquisition

  capsule

  urease - to acquire ammonia in blood and tissue fluids
• Actinobacillus predisposing factors

  viral infections, trauma, stress, low maternal immunity
• Actinobacillus pleuropneumoniae (porcine pleuropneumonia)


  asymptomatic carriers in tonsils

  considered primary respiratory pathogen

  highly contagious

  high morbidity, high mortality

  all ages are affected
• Actinobacillus pleuropneumoniae peracute and acute forms 


  necrotizing fibrino-hemorrhagic pneumonia with pleuritis

  hemorrhage and severe congestion in lungs

  serosanguinous exudate in pulmonary cavity
• Actinobacillus pleuropneumoniae chronic form 


  in animals that survive infection

  lung lesions - focal necrotic abscesses with layers of fibrous tissue, result in scarring of the lung)
• Apx toxins and immune complexes damage endothelial cells resulting in vasculitis and thrombosis, with edema, necrosis, infarction, and hemorrhage
• Actinobacillus pleuropneumoniae toxins

  ApxI is most potent - hemolytic and leukocytic

  ApxII less potent - hemolytic and leukocytic

  ApxIII is potent cytotoxin, but not hemolytic
• Actinobacillus pleuropneumoniae pathogensis

  transmission between piglets associated with decline of maternal antibodies ~6-12 weeks of age

  development of specific immunity - >16 weeks

  tonsil colonization - detection in piglets from ~day 10 of life
• Actinobacillus suis

  colonized upper respiratory tract and vagina of healthy pigs

  opportunistic pathogen

  causes septicemia and systemic sequelae

  characterized by hemorrhages and embolic lesions

  disease is sporadic - acute septicemia in piglets (neurological signs and arthritis)

  abortion, skin lesions (petechial hemorrhages, resembling erysipelas)
• Actinobacillus equuli subsp. equuli ("sleepy foal disease")

  rare, but worldwide

  bacterium of the oral cavity of mares

  infeciton ocurs via the upper respiratory tract or umbilicus

  diarrhea follow by pneumonia, meningitis, arthritis, septicemia

  chronic form characterized by purulent arthritis and suppurative multifocal nephritis

  rarely isolated from pigs - endocarditis, metritis - high mortality in piglets
• Actinobacillus equuli subsp. hemolytic

  only in horses

  opportunistic pathogen

  causes pneumonia, metritis, abortion, and meningitis
• Actinobacillus lignieresi (wooden tongue)

  commensals of the upper respiratory tract in ruminants (nasopharynx)

  sporadic, insidious, granulomatous infection

  disease development after inoculation into mucous membranes during abrasion by rough feed
• Actinobacillus seminis

  primarily affects the male and female reproductive tracts

  rams - posthitis, epididymitis, orchitis

  ewes - metritis, abortion

  common in virgin rams and ram-lamb producing flocks

  ascending infection
• Actinobacillus spp. diagnosis

  according to symptoms

  bacterial culture - require fresh samples

  slow growing bacteria

  CO2 enriched atmosphere requirement

  serology

  screening for carriers by culture or PCR
• Actinobacillus pleuropneumoniae treatment & therapy

  therapy - proper management practices (ventilation, appropriate temperature, all-in-all-out principle)

  infection case - direct injection of antibiotic, high levels of resistance; cephalosporins, macrolides, fluoroquinolones

  vaccination - inactivated bacterins, subunit vaccines
• Actinobacillus suis treatment & control

  wild strains susceptible to ampicillin, amoxycillin, oxytetracycline

  sick pigs treated parentally

  exposed pigs treated with medicated water

  vaccination - limitation due to multiple LPS
• Actinobacillus equuli treatment & control

  effective intake of collustrum to confer passive immunity

  wild strains usually susceptible to most antibiotics

  resistance has been detected after prolonged therapy

  commercial vaccines anti-OMPs and recombinant AqxA
• Gallibacterium anatis

  gram negative with pleomorphic cell morphology

  worldwide reported

  infected range of avian hosts species

  normal microbiota of nasal and trachea, rectum and lower genitals

  septicemia in poultry

  high mordibity, high mortality

  primary organism associated with lower egg production

  zoonotic potential; reported in cattle, horses, pigs, sheep, rabbits
• Gallibacterium anatis virulence factors

  F17-like fimbriae

  GtxA toxin
• Gallibacterium anatis targets

  upper respiratory tracts - in healthy carriers

  ovary - target organ during disease

  lower reproductive tracts - in healthy carriers
• Gallibacterium anatis transmission

  horizontal - respiratory

  venereal - affects semen quality, causes epididymitis

  trans eggshell (experimentally)
• Gallibacterium anatis in egg-laying chickens

  causing reproductive tract disorders
• Gallibacterium anatis in chickens 


  oophoritis, calpingitis, peritonitis, perihepatitis, liver necrosis, pericarditis, air sacculitis, tracheitis, enteritis, septicemia
• Gallibacterium anatis in cockerels

  colonize testicle and epididymis

  cause inflammation and lower semen quality
• Gallibacterium anatis diagnosis

  culture - 24 hours at 37C on nutrient-rich plates containing blood

  
• Gallibacterium anatis treatment & control

  antimicrobial treatment

  multi-drug resistant strains frequently reported

  control stress

  trans-eggshell transmission due to fecal contamination of hatching egges must be prevented
• Streptobacillus moniliformis (rat-bit fever)

  gram negative rod, extremely pleomorphic

  fastidious

  ferments range of carbohydrates

  culture - requires brain-heart infusion base meduim, enriched with 10-30% blood or serum, or 5% ascitic fluid

  reservoir - nasopharynx of rats and small carnivores
• Streptobacillus moniliformis in wild mice

  severe clinical disease

  welling of joints and lymph nodes to bronchopneumonia, abscess formation in liver, septicemia
• Streptobacillus moniliformis in turkeys and mice

  septicemic infections lead to polyarthritis or synovitis and often death
• Streptobacillus moniliformis in dogs (rare)

  vomiting, diarrhea, arthritis in hind legs

  bites lesions are inflammatory and often purulent or necrotic
• Streptobacillus moniliformis - cats, dogs, and pigs can be infected without symptoms
• Streptobacillus moniliformis in calves

  pneumonic lesions
• Streptobacillus moniliformis in humans

  rat-bite fever

  Haverhill fever by ingestion of contaminated food or water

  fever, headache, vomiting, rash on hands and feet, polyarthralgia (later)
• Spirillum minus

  anothe cause of rat-bite fever in humans

  does not affect other animals

  cannot be culture in artificial media

  guinea pigs or mouse inoculation for diagnosis
• Chromobacterium violaceum

  gram negative rods, slightly curved

  saprophyte of soil and water in subtropical and tropical regions

  suppurative pneumonia - pigs, cattle, dogs

  barred or bipolar staining in gram-stained smear

  lateral and polar flagella

  causes human disease
• Chromobacterium violaceum in calf

  suppurative omphalophlebitis, suppurative fibrinous polyarthritis, anterior uveitis with bilateral fibrin deposition, fibrinous peritonitis, lymph node abscess, multifocal lymphacytic and neutrophilic encephalitis with multifocal hemorrhages
• Riemerella anatipestifer

  infects ducks and turkeys

  causes septicemia in ducklings under 6 weeks age

  mortality may be up to 70%

  transmission - respiratory tract and skin wounds
• "New duck disease"/"Duck septicemia" (Riemerella anatipestifer)


  weak, tired, hardly move legs, incoordination, neurological disorder, dyspnea

  postmortem lesions - fibrinous exudate in serosal cavities, air sacs, and meninges

  chronic localized skin lesions