Actinobacillus is a genus of Gram-negative bacteria that are commensals in the oral cavities and intestinal tracts of animals. Some Actinobacillus species can cause disease in farm animals, including A. lignieresii which causes wooden tongue in cattle, A. pleuropneumoniae that causes pleuropneumonia in pigs, and A. equuli that causes sleepy foal disease in horses. Haemophilus are fastidious Gram-negative rods that are commensals in the respiratory tracts of animals. Some pathogenic Haemophilus include H. somnus (formerly H. somni) that can cause septicaemia and thrombotic meningoence

1. Actinobacillus
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2. General Characteristics
• Actinobacillus species
- non-motile,
- non-spore forming,
-Gram-negative rods
• Sometimes coccobacillary in
appearance.
• Facultative anaerobes
• Ferment carbohydrates producing
acid but not gas.
• Most species are urease- and
oxidase-positive.
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3. Usual habitat
• Actinobacilli are commensals on mucous membranes
- upper respiratory tract
- oral cavity
• cannot survive for long in the environment,
• carrier animals play a major role in transmission
• Actinobacilli exhibit some host specificity
• mainly pathogens of farm animals.
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4. Growth and reactions on MacConkey agar
• A. lignieresii, A. equuli and A. suis grow well on MacConkey agar.
• Colonies of A. lignieresii are initially pale turning pink after 48
hours.
• A. equuli and A. suis ferment lactose, producing pink colonies.
• A. pleuropneumoniae and A. seminis do not grow on MacConkey
agar
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5. Important pathogens
Species Disease
A. lignieressi Wooden tongue in cattle
A. pleuropneumoniae Pleuropneumonia in pig
A. equuli Sleepy foal disease
A. suis Septicaemia; Pneumonia in piglets
A. seminis Epididymitis in ram
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6. Actinobacillosis- Wooden tongue
• Actinobacillus lignieresii - is a commensal of the oral cavity and the
intestinal tract.
• Enter tissues through erosions or lacerations in the mucosa and
skin.
• A chronic pyogranulomatous inflammation of soft tissues
• Induration of the tongue, referred to as timber tongue.
• Also affects oesophageal groove and the retropharyngeal lymph
nodes
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7. Actinobacillosis- Wooden tongue
• Difficulty in eating and drool saliva
• Esophageal groove can lead to
intermittent tympany
• Enlargement of the retropharyngeal
lymph nodes can cause difficulty in
swallowing
• Lesions may be found on the head,
thorax, flanks and upper limbs.
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8. Treatment and Control
• Sodium iodide parenterally or
potassium iodide orally
• Potentiated sulphonamides or a
combination of penicillin and
streptomycin
• Oral isoniazid for 30 days for refractory
lesions.
• Rough feed or pasture should he
avoided.
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9. Sleepy foal disease
• Sleepy foal disease is an acute, potentially fatal septicaemia of
newborn foals
• Caused by Actinobacillus Equuli
• May cause abortion, septicaemia and peritonitis, in adult horses
• The organism is found in the reproductive and intestinal tracts of
mares.
• Foals can be infected in utero and after birth via the umbilicus.
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10. Sleepy foal disease
• Affected foals are febrile and recumbent. Death usually occurs in 1 to 2
days.
• Recovered Foals develop polyarthritis, nephritis, enteritis or pneumonia.
• Foals dying within 24 hours of birth have petechiation on serosal surfaces
and enteritis.
• Meningoencephalitis can be detectable histologically
• Foals which survive for 1 to 3 days have typical pin-point suppurative foci
in the kidneys.
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11. Treatment and Control
• Unless the disease is detected early, antimicrobial therapy is of little benefit.
• The organism is usually susceptible to streptomycin, tetracyclines and ampicillin
• Supportive treatment includes blood transfusion and bottle-feeding with
colostrum.
• Mares which have had affected foals should be monitored closely at subsequent
foalings.
• Prophylactic antibiotic therapy may be considered for newborn foals.
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12. Pleuropneumonia of pigs
• Caused by A. pleuropneumoniae,
• Affect susceptible pigs of all ages.
• Worldwide occurence
• highly contagious disease, primarily in
pigs under 6 months of age,
• Incidence more in intensive rearing
practices
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13. Pathogenesis and pathogenicity
• Capsules antiphagocytic and immunogenic,
• Fimbriae and other adhesins
• Cytotoxins producing pores in cell membranes.
• Neutrophils -damaged and release lytic enzymes
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14. Clinical signs and epidemiology
• Subclinical carrier pigs, -tonsillar tissues.
• Poor ventilation and sudden drops in ambient temperature
• Aerosol transmission occurs in confined groups.
• some pigs may be found dead and others show
• dyspnoea, pyrexia, anorexia and a disinclination to move.
Blood-stained froth
• may be present around the nose and mouth, and many pigs
show cyanosis.
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15. Clinical signs and epidemiology
• Pregnant sows may abort.
• Morbidity rates can range from 30-50% and case fatality rates may reach
50%.
• Pasteurella multocida and Mycoplasmas
• At post-mortem areas of consolidation and necrosis are found in the
lungs along with fibrinous pleurisy.
• Blood-stained froth may be found in the trachea and bronchi.
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16. Treatment & Control
• As antibiotic resistance is encountered in some strains, chemotherapy
should be based on the results of antibiotic susceptibility testing.
• Prophylactic administration of antibiotics to in-contact pigs may limit the
severity of clinical disease.
• Polyvalent bacterins may induce protective immunity but fail to prevent
transmission or the development of a carrier state.
• A subunit vaccine containing toxoids of the three A. pleuropneumoniae
toxins and capsular antigen has been developed (Valks et al., 1996).
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17. Actinobacillus suis infection of piglets
• Actinobacillus suis may be present in the upper respiratory tract of
sows
• Piglets become infected by aerosols or possibly through skin
abrasions.
• The infection occurs mainly in young pigs under 3 months of age.
• The disease is characterized by septicaemia and rapid death.
• Mortality may be up to 50% in some litters.
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18. Actinobacillus suis infection of piglets
• Clinical signs include:
- fever,
- respiratory distress,
-prostration and paddling of the forelimbs
• Petechial and ecchymotic haemorrhages occur in many organs,
interstitial pneumonia, pleuritis, meningo-encephalitis, myocarditis
and arthritis
• An unusual form of the infection in mature pigs - skin lesions
resembling those of swine erysipeIas
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19. Haemophilus
Dr. Pankaj Kumar
Assistant Professor
Veterinary Microbiology
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20. General characteristics:
• Haemophilus species are small, pleomorphic, Gram-
negative rods
• Often appear coccobacillary (occasionally in short
filaments)
• Motile; Facultative anaerobes
• variable reactions in catalase and oxidase tests
• do not grow on MacConkey agar
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21. General characteristics:
• They are fastidious bacteria
• requiring one or both of the growth factors:
- X (haemin) and
- V (nicotinamide adenine dinucleotide, NAD)
• Optimal growth -5-10% C02 on chocolate agar
• Small, transparent, dewdrop-like colonies after
incubation for 48 hours
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22. Usual habitat:
• Haemophilus species are commensals
• Mucous membranes of the upper respiratory tract
• They are susceptible to desiccation
• Do not survive for long periods away from their
hosts
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23. X and V factors:
• X factor is hemin; heat stable
• V factor is – NAD
• heat-labile is susceptible to NADases in plasma
• Satellitism -Staphylococcus aureus growing on blood agar
releases V factor into the medium
• Colonies of Haemophilus species which require V factor grow
close to the S.aureus colony
• Porphyrin test – To test the requirement of X factor
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25. Important species:
Formerly (Species) Host Species name
Haemophilus somnus Cattle, Sheep Histophilus somnus
Haemophilus parasuis Pig Haemophilus parasuis
Haemophilus paragallinarum Poultry Avibacterium
paragallinarum
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26. Histophilus somnus:
• formerly k/a Haemophilus somnus
• common inhabitant of the genital tracts of male and female
cattle
• Histophilus somni also infects sheep:
- strains differ between cattle and sheep so that cross-
infection between species does not occur
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27. Histophilus somni causes a number of syndromes in cattle
•Septicaemia
•Polyarthritis
•Pneumonia/pleurisy
•Thrombotic meningoencephalitis (TME)
•Reproductive disorders: - Endometritis,
Vulvovaginitis and Cervicitis
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28. Thrombotic Meningoencephalitis (TME)
• Attacks vascular endothelium
• causing a septic vasculitis with thrombosis
• The parenchymal lesions of ischemic and hemorrhagic
infarction in CNS
• Similar vascular lesions can occur in the lung, heart, skeletal
muscle, and joints
• Death may occur acutely without evidence of neurologic signs.
• Pyrexia is present in clinically ill patients.
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29. Infection in Sheep:
• Normal commensal
• Present in prepuce or vagina
• Young ram- Epididymitis
• Vulvitis, reproductive disorders, Mastitis
• Other: Septicaemia, arthritis, meningitis, Pneumonia in
lambs
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30. Glassers disease:
• Caused by Haemophilus parasuis
• Organism often can be isolated from the nasal
cavity or tonsil of normal pigs
• H. parasuis is widely distributed in the swine
population and not associated with disease
• Disease occurs sporadically
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31. Glassers disease:
• Usually observed in 3 wks to 4 month-old pigs
• Predisposing factors: Weaning, transportation
changes in environment, commingling, or as co-
infection
• Colostral antibodies usually protect pigs from
disease
• They gradually develop an active immunity by the
time they are 7-8 weeks old
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32. Glassers disease:
• H. parasuis has predilection for growth on serosal surfaces:
- peritoneum
- pleura,
- pericardium
- joints,
- meninges
• Anorexia, pyrexia, lameness, recumbancy, convulsion are
observed
• Manifested as polyserositis, lepto-meningitis
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33. Clinical Sign and symptoms:
• Onset is usually sudden
• They may be found dead or die after a disease course of less than
two days
• In most cases there is an initial, marked rise in temperature, along
with anorexia and depression
• Sudden deaths may occur in any age group
• Sometimes signs suggestive of septicemia or myositis
• Morbidity usually is low but mortality is high
• Signs depend upon where the organisms localize
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34. Clinical Sign and symptoms:
• Signs of central nervous system (CNS) disturbance often predominate
• As a consequence of localization of H. parasuis in the brain, meninges
and spinal cord
• Signs may then include tremors, incoordination, posterior paresis or
lateral recumbency
• Often there are swollen leg joints - in some outbreaks arthritis
predominates and the animal will favor an affected leg while walking
• H. parasuis is also commonly isolated from pneumonic lungs.
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35. Infectious Coryza:
• Caused by Avibacterium paragallinarum
• A serious bacterial disease of chickens which affects respiratory
system
• Affects the upper respiratory tract and paranasal sinuses of chickens
• Economically importance - reduced egg production in laying birds
• Chronically ill birds act as reservoirs
• Transmission occurs by direct contact, by aerosols or from
contaminated drinking water.
• Chickens become susceptible at about 4 of age and susceptibility
increases with age
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36. Clinical signs:
• The mild form of disease manifests as depression, serous
nasal discharge and slight facial swelling
• Severe cases ch/by swelling of one or both infraorbital
sinuses
• Marked oedema of the surrounding tissues may extend to
the wattles
• A copious, tenacious exudate may be evident at PM in the
infraorbital sinuses
• Tracheitis, bronchitis and airsacculitis may be present
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37. Diagnosis:
• Haemophilus species are highly fragile
• Specimens should be frozen in dry ice
• Chocolate agar or blood agar with S. aureus stream may be inoculated
• Identification criteria for isolates :
-Small, dewdrop-like colonies after 1 to 2 days
-Enhancement of growth by CO2
-Requirement for X and V growth factors
-Biochemical profile
• Serological tests are of little diagnostic value
• PCR may be used
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38. Brucella
Dr. Pankaj Kumar
Assistant Professor
Veterinary Microbiology
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39. General characteristics
• Brucella species are small, nonmotile,, Gram-
negative coccobacilli.
• They are MZN-positive.
• In MZN-stained smears they characteristically
appear as clusters of red coccobacilli
• They are intracellular parasites.
• Grow poorly on ordinary media.
• They are non-hemolytic on blood agar.
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40. Important species
• Brucella abortus- affects cattle
• Brucella melitensis- affects sheep and goats
• Brucella suis- affects pigs
• Brucella ovis- affects sheep
• Brucella canis- affect dogs
• Brucella neotomae- affect desert wood rat
• B. abortus is most prevalent Brucella spp
• B. melitensis is most virulent Brucella spp.
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41. • Aerobic, capnophilic and catalase-positive.
• Except B. ovis and B. neotomae, others are oxidase-positive.
• All Brucella species are urease-positive except B. ovis.
• Growth of other Brucella species is enhanced in an atmosphere of C02.
• B. abortus, B. melitensis and B. suis occur in smooth forms
• B. ovis and B. canis always occur in rough forms.
General characteristics
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42. Differentiation of Brucella species
• Two important surface antigens are abortus antigen A and melitensis antigen M.
• The proportion of A : M antigen
Brucella abortus- 20:1
Brucella melitensis:1:20
Brucella suis- 11:9
• B. abortus are lysed by a specific bacteriophage (Tbilisi phage) at routine test
dilution.
• B. abortus grows in presence of basic fuchsin but not in presence of thionin.
• B. suis grows in presence of thionin but not in presence of basic fuchsin.
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43. Cultural requirement
• Do not grow on ordinary media.
• Addition of blood or serum supports growth
• Trypstose agar or Liver infusion agar gives satisfactory
growth.
• B. abortus and B. ovis requires 10% CO2.
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44. Usual habitat
• Brucellae have a predilection for both female and male reproductive organs in
sexually mature animals.
• Each Brucella species tends to infect a particular animal species.
• Infected animals serve as reservoirs of infection which often persists
indefinitely.
• Organisms, shed by infected animals, can remain viable in a moist
environment for many months.
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45. Pathogenesis
• Rough colonies and are less virulent than smooth colonies.
• Organism can gain entry in the host even through the mucous membrane,
abraded skin and conjunctiva.
• Inhibition of phagosome-lysosome function intracellular survival
• Superoxide dismutase and Catalase - resistance to oxidative killing
• Brucellae persist within macrophages but not within neutrophils
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46. Pathogenesis
• Bacteraemia - spread and localization in the reproductive organs
• Associated glands in sexually mature animals
• Erythritol is 4 carbon sugar alcohol that stimulates growth of Brucella organism
• High concentrations - placentae of cattle, sheep, goats and pigs
• Also found in other organs -mammary gland and epididymis
• In chronic brucellosis, organisms may localize in joints or inter-vertebral discs.
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47. Brucellosis in cattle
• Brucellosis in cattle due to B. abortus is called Bangs disease.
• Brucella organism are obligate parasite and have predilection for
genital tract and joints.
• Cows may be infected by:
- Ingestion
- Inhalation
- AI or natural service
• Infected cows secrete brucella organism in:
- vaginal discharge
- placenta
- aborted foetus
- milk
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48. Brucellosis in cattle
• Usually abortion is seen in third trimester.
• “Abortion storm” is observed in herd with large number of
susceptible pregnant animals.
• Cows abort only once.
Symptoms in cattle are:
• Abortion;
• Stillborn.
• Weak calf born.
• Retention of fetal membranes;
• Signs of infection in the membranes;
• In bull- Epididymitis is observed
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49. Diagnostic procedures
• Specimens should be processed in a biohazard cabinet.
• The diagnosis of brucellosis depends on serological
testing.
- MRT
- RBPT
- STAT
• Isolation and identification of the Brucella species.
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50. Serological test
• Milk ring test (MRT) or Abortus Bang’s ring (ABR) test:
- This test is performed to identify brucella in herds.
- It is based on detection of antibodies in milk against stained antigen
• Rose Bengal Plate test (RBPT): Qualitative test for screening.
• Standard Tube Agglutination Test (STAT): Quantitative test- Confirmatory
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51. Sl No Name of the test Antigen Sample to be
tested
Nature Purpose
1. Milk ring test
Or
Abortus bang ring
test.
Killed brucella
organism stained with
_______
Milk Qualitative This test is carried out to
detect brucellosis in herd.
2. Rose Bengal Plate
test
(RBPT)
Killed brucella
organism stained with
“Rose Bengal” dye
Serum Qualitative This test is carried out in field
condition to detect affected
animals from MRT positive
herd.
3. Standard Tube
agglutination test
(STAT / SAT)
Killed Brucella
organism unstained
Serum Quantitative A titre of 1:40 is considered
positive whereas 1:20 is
doubtful.
Serological tests:
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52. Diagnostic procedures
• Specimen: cotyledons, foetal abomasal contents and uterine discharges
• MZN-stained smears often reveal MZN-positive coccobacilli.
• In specimens containing cells, the organisms appear in clusters.
• The polymerase chain reaction can be used to detect brucellae in tissues.
• Strauss reaction: Development of orchitis in G. pig after intraperitoneal
injection of infective material.
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53. Treatment and control
• Treatment of cattle with brucellosis is not
practical.
• Immunity in brucellosis is predominantly cell
mediated.
• Three vaccines are in use
- strain 19 (S19) (Cotton strain 19)
- adjuvanted 45/20 vaccine ,and
- RB51 vaccine
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54. Brucella -Vaccine
• S19 vaccine is administered to female calves up to 5 months of age (Calf
hood vaccination).
(Vaccination of mature animals leads to persistent antibody titres)
• 45/20 bacterin - Even when administered to adult animals, this vaccine does
not induce persistent antibody titres.
• RB51 strain is a stable, rough mutant which induces good protection against
abortion and does not result in serological responses detectable in tests.
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55. Brucellosis in humans
• Humans are susceptible to B. abortus, B. suis, B. melitensis and, rarely, with B.
canis.
• Severe infections occur with B. melitensis (Malta fever) and B. suis biotypes 1 and
2. Human infections due to B. abortus are moderately severe whereas those
caused by B. canis are usually mild.
• Transmission to humans occurs through contact with secretions or excretions of
infected animals.
• Routes of entry include skin abrasions, inhalation and ingestion.
• Raw milk and dairy produce made with unpasteurized milk are important sources
of infection.
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56. Brucellosis in humans
• Brucellosis in humans, known as undulant fever, presents as:
- Chill
- fluctuating pyrexia,
- perspiration
- malaise,
- fatigue and
- muscle and joint pains
• Abortion is not a feature of human infection.
• Osteomyelitis is the most common complication.
• Antimicrobial therapy should be administered early in an infection.
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57. THANKS
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