Brucella

1. GenusBrucella

2. Genus Brucella has 6 species namely:
B. abortus, B. canis, B. melitensis, B. ovis, B. suis
except B. neotome (important pathogens of domestic
animals and man)
Brucellosis = disease cause of this bacterial
pathogen
Infections = reproductive organs and
reticuloendothelial tissues
Abortion = in cattle, sheep, goat because of the
lesions of the female reproductive tract and of the
placenta and fetus.
Transmission = directly or indirectly from infected
animls to humans (there is a zoonotic importance
because of this)
Brucella melitensis = first member of the genus to be
isolated by David Bruce in 1887
Source = from the spleens of patients who died in
Mediterranean or Malta fever
Brucella abortus = the second member was isolated
by Fredrick Bang in 1897
Source = aborted bovine fetus

3. Brucella suis = isolated by Jacob Traum in 1914
Source = aborted piglet
B. Ovis and B. canis = more highly host adapted and
they were isolated in 1956 and 1969 respectively
Morphological and cultural features of the 6 members
= not sufficiently characteristic to differentiate. Nor
the host from which the organism is isolated . But
each species have a predilection site for certain
hosts.
*Isolation of a Gram-negative rod from a suspected
case of brucellosis requires reliance on the results of
the laboratory tests.

4.   B. suis  
  B. melitensis  
B. canis B. abortus humans
  B. neotome wood rats
B. suis    
B melitensis    
B. abortus B. canis dogs
B. abortus    
B. melitensis B. suis pigs
B. suis B. abortus horses
B. abortus B. melitensis goats
  B. ovis (epididymitis)  
B. abortus B. melitensis sheep
B. suis    
B. melitensis B. obortus cattle

O th e r p a th o g e n ic
Brucella sp.
Is o la te d

P rin c ip a l

p a th o g e n ic
Brucella
sp.
Is o la te d
H o s t
The species of Brucella and other
principal hosts

5. Brucella
abortus

6. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Affected animal = cattle population (absent in
countries where eradication programs have been
actively pursued)

Mo rpho lo g y a nd S ta ining re a c tio n

= short rod / a coccobacillus (0.5 to 0.7 µm by
0.6-1.5 µm.)
=rods are short that are mistaken to be a cocci
=arranged singly, although in cultures appear to be in
short chains
= a facultative intracellular bacterium
= found in clumps and smears made from exudates
=Gram negative and stains with ordinary stains
although with some difficulty
=not acid fast
=Can resist decolorization with some mild acids.

7. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Koster stain = which the organism stains deep red
Other characteristics = nonmotile, doesn’t form spore,
doesn’t have a well-developed capsule (poorly
developed capsules have been demonstrated on
freshly isolated strains using special stains)

Cultura l a nd bio lo g ic a l fe a ture s
=aerobic growth (many strains require increased
tension of CO
2
for growth especially on primary
isolations
= is catalase and oxidase positive and usually produce
H
2
S from protein or peptides rich in amino acids
containing sulfur
=produces urease
=8 biotypes are currently recognized by dye sensitivity
test, CO
2
requirement, H
2
S production, and presence
of A or M Antigen.
= not hemolytic, doesn’t liquefy gelatin, doesn’t
produce acid from glucose
= It has a characteristic substrate oxidation pattern

8. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Growth = enhanced by serum or blood
Tool for primary isolation = complex media (serum
dextrose agar or Albimi Brucella agar or broth)
Antibiotics = they are sometimes added to these
basal media to inhibit contaminants in specimens
such as milk and vaginal discharge.

Prima ry is o la tio n
= they are slow-growing and barely visible at 48
hours
= reach maximum size after 5- 7 days at the optimum
growth temperature (37
o
C)
= may be on a smooth type characterized by a round
convex colonies with an entire edge or they may be
associated by rough type colony in which they have
large flat colonies with a dull granular appearance.
=growth is sparse in fluid media and appear as a
faint clouding.

9. Brucella abortus
(Bacillus abortus, Bang’s bacillus)

Ba c te rio pha g e Typing
Bacteriophage = often used for identifying and typing
cultures of Brucella sp.
Tb, Wb, Fi, Bk2, and R strains = the phages currently
in routine
Rotuine Test Dilution (RTD) = dilution of the phage;
the minimum number of phages that will produce
confluent lysis on a lawn of the propagating strain
Phage typing = is rapid and very useful tool of
identifying B. abortus
Antig e n
cell wall of B. abortus = consists of an outer layer of
lipopolysaccharide protein on which polysaccharide
chains are exposed
Polysaccharide chains = carries the major antigen (A
and M) involved in the agglutination reaction

10. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
cell wall proteins have been grouped into three =
88,000-94,000. 95,000-40,000 (porins); and
25,000-30,000

Epizo o tio lo g y a nd Pa tho g e ne s is
B. abortus = an obligate facultative intracellular
parasite of cattle and some wild ruminants; they are
not very resistant to sunlight and drying and therefore
survives better in winter than summer; can survive
and grow in host macrophages and epithelial cells
Transmission = ingestion of contaminated discharges
or feed; venereal transmission is possible but
unusual; intramammary and congenital transmission
also occur
Other infected animals = horses, sheeps, chickens,
and dogs

11. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
survives = in milk
destroys = pasteurization
Large dairy herds = more likely to be infected with a
high prevalence of infection within the herd. the
greater level of intensivism and opportunity for
transmission within large herds together with the
greater likelihood of introduction of a latently infected
animals are some of the factors that contributes to
the higher risk of infection in large herds
factor of transmission = common pastures,
contaminations of streams, activities of carrion
feeders
Brucella infection in free-living animals = bison,
moose and elk (comingling with this animals in cattle
enhances the possibility of cross-infection)
Prepubescent animals = resistant to infection

12. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Heifer calves = can be infected early in life either in
utero from infected dams or by ingestion of
contaminated milk (susceptibility increases with sexual
development and pregnancy)
Latent infection = cannot be detected by serological
test in calves exposed in this way
Male cattle = resistant to infection but infection of the
epididymis and testicle has been recorded (Bulls can
transmit the infection in their semen)
Main portals of entry = oral mucosa (milk),
nasopharynx, and conjunctiva of cattle as well as the
genital tract in both bulls and cows
experimental conditions = organisms has been shown
to penetrate the unbroken skin of guniea pig and
cattle. after penetrationof the host, B. abortus initially
localizes in the regional lymph node and then enters to
the blood stream.

13. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
bacteremic phase = results in dissemination of the
organisms to the udder, uterus, and associated nodes.
B. abortus = has an unusal resistance to
intraleukocytic killing; proliferates massively in cells
with high levels of erythritol (found in genital tract in
male and pregnant female)
*it penetrates the epithelial cells of the chorion and
proliferates, producing placentitis.
*Endometritis is produced with ulceration of the
epithelial lining of the uterus.
*Lesions of the fetus include edema and congestion of
the lungs along with hemorrhages of the epicardium
and splenic capsule.
*fetal death occurs (it is unclear whether endotoxin of
the organism or to interference with placental function)

14. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
*inflammation of the membranes (this interference with
the circulation of the fetus may explain why abortion
occurs)
*organisms found in the stomach and lungs of aborted
fetuses
*abortion occur late in pregnancy
*organism is present in large numbers in uterine
discharges for a few days but is then gradually cleared
from the reproductive tract (after calving or abortion)
*infection is maintained in the reticuloendothelial tissue
and the udder
Milk = source of infection for calves and also humans
(shed in large numbers)

15. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
*abortion are usually seen only during the first
pregnancy after infection (placenta is infected during
each pregnancy)
*organisms are seen in the lymph nodes of the
digestive tract and in the spleen in the infected cattle.
*it has been isolated from the blood and from
hygromas of the knee (shows high correlation with
brucella abortion in African cattle)
B. abortus in horses = less frequency than in cattle;
frequently localizes in bursae, joints, or tendon sheath
and has been found in poll evil and fistulous withers,
supra-atlantal bursitis, and supraspinous bursitis as
well as in lesions of the fetlock and sternum.

16. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Immunity
*the organisms are so readily escapes the bactericidal
effects of antibody and complement in plasma
protective immunity = depends mainly on cell-
mediated responses in which the microbicidal activity
of macrophages is enhanced following activation by
lymphokines from sensitive T- lymphocytes.
*the organism has been shown to multiply more slowly
in the macrophages of vaccinated calves than in
control animals.
humoral antibodies = correlate poorly with protective
immunity
Strain 19 vaccines = cattle vaccinated by this have
been shown to be resistant to challenge after antibody
titers fall below detectable levels
IgM agglutinins = first antibodies to appear in the
plasma and their levels reach a peak at about 2
weeks; IgG antibodies appear later.

17. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
IgG1 subclass = infected cattle have high titers of
nonagglutinating antibody
pH 3.6 = treatment with acid at this level activates their
agglutinating ability.
strain 19 = IgM antibody levels increase rapidly in
calves vaccinated with this strain; IgG1 antibody levels
rise more slowly, do not attain high high levels and do
not persist. also, levels of nonagglutinating IgG1
antibodies are much lower than in naturally infected
animals.
protective immune responses = appear to be most
effective when infection occurs before puberty. the
majority of infections in sexually mature animals
persist for life although the immune response does
reduce the severity of disease in the uterus and
placenta so that such animals are more likely to carry
to term later in pregnancies.

18. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Va c c ine s
strain 19 and the McEwen killed 45/20 = two vaccines
that are important in the control of B. abortus infection
19
S tra in
= consists of viable culture of a strain that was
discovered to have very little virulence for guinea pigs
and cattle but to possess excellent immunizing
properties.
= it has a great stability
= it is a smooth strain that is mildly pathogenic for
guinea pigs
= pregnant cattle can be made to abort by inoculating
them with large doses of this

19. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
= vaccine organisms can usually be demonstrated
without difficulty in the fetal membranes and the fetus
itself
= susceptible cattle, associating with those have
aborted as a result of inoculation with the vaccine
strain, do not become infected
= it is unlikely transmitted from one animal to another;
if any damage is done by the use of this vaccine, it is
limited to the animal injected.
= it is rarely shed in milk of vaccinated animals
= it can cause infection to humans, although it is
usually mild with recovery in a much shorter time than
with virulent strains
= it is dangerous to humans and should be handled
with caution
= calves are vaccinated 2-10 months of age
(vaccination at this age is advocated to avoid
persistent agglutinins that could create diagnostic
problems later in the animal’s life)

20. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
= it protects about 65-70 percent of animals for 4 or 5
pregnancies and is most effective for protection of
young breeding animals when applied in a herd basis.
= animals vaccinated as adults are also protected but
develop persisting agglutinins.
= Latently infected animals or animals in the early
stages of infection do not benefit from vaccination.
Colostral antibodies may interfere with response to
strain 19 during the first 5 months of the calf's life.
= vaccination of cows in early pregnancy with large
doses produces probability of uterine infection. this risk
is greatly diminished when the dose is reduced.
= horses with fistulous withers sometimes treated by
this vaccination

21. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
4 5 /2 0
Mc Ew e n kille d va c c ine
= a rough strain that is inactivated and adjuvanated for
use as a vaccine or antigen in the anamnestic
diagnostic test
= it is administered in two doses (6- 12 weeks apart)
= it stimulates complement fixing antibodies and
agglutinins for rough B. abortus antigens of the IgG1
subclass
= it has been used widely for the control of bovine
brucellosis

22. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Dia g no s is
bacteriologically and serologically = B. abortus can be
diagnosed by these.

Ba c te rio lo g ic a l dia g no s is

= isolation and recognition of B. abortus are often
accomplished by direct culture on a basal medium
such as tryptose agar or Albimi agar to which serum
and selected antibiotics are added.
= cultures are incubated at 37
o
C in an atmosphere of
10 percent co2 tension and are examined 2-3 days
=serologic typing of Brucella strains and phage typing
with the Tbilis (Tb) strain of bacteriophage are useful
aids to definitive identification, but their use in
restricted to specifically equipped reference
laboratories

23. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Specimens should be examine by the following:
1. The aborted fetus = direct cultures of specimens of
the stomach contents, intestinal contents, or the lung
tissue
2. the placenta = direct stained smears from the outer
surface of the chorion, especially from the margins of
the characteristic thickenings, will usually suffice to
make positive diagnosis without the need for cultural
method (the organisms occur free or enclosed in the
epithelial cells). these are visualized using the
modified Koster stain by which appear red against a
blue background.

24. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
3. The uterine exudate = after abortion or calving,
when the placenta has been infected in the lochia and
can be recognized by guniea pig inoculation.
(organisms seems to disappear and cannot be found
at the uterus until the animal is again pregnant and
reinfection of the organ occurs)
4. milk = udder is infected and detected by the
intraperitoneal injection in milk into guinea pigs or by
direct culture
5. abscesses = direct culture of specimens from
abscesses of the testicle and epididymis usually
produced pure cultures, and isolations have been
made from hygromas in cattle and from infected
bursae in horses.

25. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Inoculation of guinea pigs = most reliable method of
detecting B. abortus in infected materials. their serums
are examined for the presence of antibodies and
specimens from the spleen, liver, regional lymph
nodes, testicles are cultured.
Direct examination of tissues and fluorescent antibody
= aid to diagnosis and practically useful for examining
contaminated materials (placental membranes,
cotyledons, fetal or vaginal discharges).

26. Brucella abortus
(Bacillus abortus, Bang’s bacillus)

s e ro lo g ic a l dia g no s is
=the test are applied to serum, whole blood, vaginal
mucus, seminal plasma, whey, or milk.
Serum tube agglutination test (SAT) = used in
eradication programs; The test is performed in small
test tubes on dilutions of serum. Complete
agglutination at a serum dilution of 1:100 and higher is
considered positive. In Great Britain, a titer at least 50
percent agglutination at 1:40 is considered positive
Flase-positive reaction = can be caused by reactions
of antibodies to Yersinia enterocolitica 09 and other
Gram-negative organisms. It occur in a significant
number of serum sampls from latently or chronically
infected animals. Animals in the early stage of
infection similarly may fail to react.

27. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Buffered antigen plate agglutination tests = replaced
standard SAT because the use of buffered antigen
reduces the frequency of false-positive reactions
Rose bengal plate tests = B. abortus cells stained with
rose bengal and suspended in acidic buffer to inhibit
nonspecific agglutinins. The test can be used as a
screen or definitive test. The frequency of false-
negative reactions is less than for the SAT
Card test = the antigen is a buffered, stained, whole
cell suspension of B. abortus strain. the antibody
source is plasma separated from blood following
clumping or erythrocytes by lectins. the test is useful
for the detection of early infection where IgM is the
dominant antibody.

28. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Plate agglutination = test is a heavy suspension of
strains of B. abortus stained with gentian violet and
brilliant green to make the test easier to read. Serum,
whole blood, or whey can may be used in this test.
(using glass slide or plate)
whole-blood method = used for testing range cattle
when it is desirable to hold the animals in chutes until
the results are known
Milk ring test = the antigen is a hematoxylin-stained
suspension of killed B. abortus. It is mixed with fresh
milk in a tube in the proportion of one drop per
milliliters of milk. the mixture is then incubated in a
water bath at 37oC for 1 hour.

29. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
clumps of agglutinated organisms= a positive test is
indicated by a bluish violet cream layer and a
decolorized milk column. The test is widely used for
the examination of bulk milk samples and so allows
herds in an area to be quickly and economically
screened. positive herds are then subjected to blood
tests on individual animals.
complement-fixation test = one of the most accurate
tests in widespread use for the diagnosis of B. abortus
infection. It detects IgM and IgG1 antibodies only. The
test does not differentiate infected animals from
animals recently vaccinated with strain 19 or 45/20.
This test designed to test antibody to the 45/20
vaccine is also available. And for that, the test has
been automated in many laboratories thus resulting in
greater precision.

30. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Antiglobulin (coombs) test = measures binding of
nonagglutinating antibodies to B. abortus antigen.
The ravinol and mercapteothenol tests = used to help
distinguish between agglutinin titers caused by chronic
infection and those caused by vaccination with strain
19. IgM antibodies are sensitive to mercaptoethenol.
Enzyme-linked immunosorbent assay (ELISA) = offer
promise of greater sensitivity and specificity than the
test described above.
Allergic skin test = based on purified antigens; is to be
a valuable addition to serology for detecting animals.

31. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
Co ntro l
1. affected animals are detected and eliminated from
the herd (detection using serological test - milk ring
test - agglutination test - slaughter)
2. resistance of the remaining animals or any
replacements is increased by vaccination
3. General principles of hygiene are imposed to
prevent spread or reintroduction of infection
systematic calf vaccination = a protective measure in
herds that are only lightly infected
systematic calfhood vaccination with strain 19 or 45/20
= is used in heavily infected herds

32. Brucella abortus
(Bacillus abortus, Bang’s bacillus)
calfhood vaccination = it is maintained in such a herd
as long as there is a real danger of the exposure to the
disease from any source
periodic milk-ring tests and random testing on serum=
surveillance of herd is maintained on bulk milk
samples when they are sent to slaughter
back-tagging = allows infection to be traced back to
the her of origin

33. Brucella abortus
(Bacillus abortus, Bang’s bacillus)

Antimic ro bia l s e ns itivity
Gentamicin, kanamycin, tetracycline, and rifampicin =
B. abortus is sensitive to these substances
tetracycline + streptomycin = treatment for human
brucellosis
*cattle are not usually given antimicrobials for
prophylaxis or therapy of B. abortus infection

34. Brucella
suis

35. Brucella suis
(porcine type of Brucella)
=caused by brucellosis in swine.
=has wider range of host specificity (humans, dogs,
rodents, horses, reindeer, musk, oxen, and wild
carnivores)
Five types are recognized = Biotype 1, 2, 3, 4, and 5
Biotype 1, 2 , 3 = have the pig as their natural host but
can be transmitted to other host
Biotype 2 = occurs naturally in horses and relatively
avirulent for humans
Biotype 4 and 5 = reindeer and rodents are the
primary natural hosts (but others can be infected).

36. Brucella suis
(porcine type of Brucella)

Mo rpho lo g y a nd S ta ining re a c tio n
B suis is closely resembles B. abortus

Cultura l a nd Bio c he mic a l Fe a ture s
=does not require increased levels of CO
2
for growth.
= large amounts of H
2
S are produced by Biotype 1 but
more produce by other biotypes
= Urea is highly hydrolyzed

37. Brucella suis
(porcine type of Brucella)
Antig e n
=surface antigen predominates a smooth cultures of
all biotype except biotypes 4 and 5
Biotype 4 = has both A and M antigens in equal
amounts
Biotype 5 = has mostly M antigens on its surface

Epizo o tio lo g y a nd Pa tho g e ne s is
= it occurs to most swine raising areas (not been
reported in Great Britain, Iceland, or Canada)
= Survival in the environment has not been well
studied (but similar to B. abortus)
Feces and urine = the organisms survives at least 6
weeks

38. Brucella suis
(porcine type of Brucella)
Feral swine= is most infected than domesticated
swine; can be also a source of infection for cattle
Biotype 1 = is isolated from tissues of wild swine
wild boars = important reservoirs of B. suis biotype 2
source of infection = contaminated pastures from
these hosts can infect domesticated swine
Reindeer (Rangifer tarandus) = brucellosis is an
important disease; B. suis biotype 4 has been isolated
from them; it cause bursitis, spondylitis, arthritis, and
orchitis
Larvae of reindeer warble fly = seen the B. suis
organism and there is a speculation that this insect
may act as a vector of this disease

39. Brucella suis
(porcine type of Brucella)
Wolves of Siberia and sled dogs in Alaska = seen B.
suis because they fed on infected reindeer meat
Soviet Union = brucellosis is of particular interest and
significance because of the large number of their free-
living reindeer
Domestic guard dog = seen to be a carrier of B. suis
biotype 2 (source of infection for a herd of domestic
swine)
*although feral animals can be a source of B. suis
infection for pigs, the organism is transmitted almost
exclusively from pig to pig (by coitus or by the
ingestion of feed contaminated by urine or genital
excretions from infected boars or sows)

40. Brucella suis
(porcine type of Brucella)
* spread is rapid in a susceptible herd
* outbreak of disease followed by intermittent cases as
susceptible newcomers contact chronically infected
pigs.
initial infection = B. suis is localized in the regional
lymph nodes. It proliferates and may cause extended
bacteremia with generalized infection of the spleen,
lymph nodes, joints, udder, and genitalia
B. suis = a facultative intracellular parasite and owes a
great deal of its pathogenic properties to its ability to
survive in the host's phagocytic cells.
Erythritol = has a growth-stimulating effect upoin B.
suis and is found in placenta of sows and seminal
vesicles of boars

41. Brucella suis
(porcine type of Brucella)
stimulatory action of eythritol + its presence on tissues
= lesions in male and female genital tracts
clinical signs and lesions produce = depends on
animal's age, previous exposure, organ or organs
involved
Suckling and weanling piglets = they can be affected
adults = can have abortion, metritis, spondylitis
(vertebra in the lumbar and sacral region are not
uncommon), lameness, and paralysis
posterior paralysis = caused by pressure from the
necrotic tissue on the spinal cord
nodular splenitis = also been associated with
brucellosis

42. Brucella suis
(porcine type of Brucella)
Immunity
field and experimental evidence = indicates the swine
immunity to brucellosis is very slight and that after a
period of herd resistance, animals are again
susceptible to the disease
Abortion = don't occur after the first exposure but when
reexposed
cell-mediated immunity = important in protecting the
host
Dia g no s is
cultural methods and agglutination test = positively
diagnose brucellosis in swine

43. Brucella suis
(porcine type of Brucella)
Isolated B. suis = from blood, spleen, uterus, lymph
nodes, and mammary glands of sows and testes and
semen of boars
*methods are the same as B. abortus except that an
increase of the CO
2
tension of the culture jar
(unnecessary)
Agglutination test = used as an aid in diagnosis but not
as reliable in swine as it is in cattle; it is valuable in
determining whether the infection exists in a herd
Card test and rose bengal test = superior to most other
serological test for detection of antibody in swine
serum
ELISA = it replaced the tube agglutination test

44. Brucella suis
(porcine type of Brucella)
Co ntro l
sell all stock to slaughter = simplest way to eradicate
the disease
*the premises should be thoroughly cleaned and
disinfected
For breeding herd in which blood lines must be
preserved = pigs are raised from the infected unit.
They are weaned (8 weeks old) and tested individually
by agglutination test
If negative = they are removed from the infected herd,
placed on a clean ground and raised in isolation
*all pigs are tested periodically (reactors are
immediately removed)
when of Breeding age = serological negative gilts are
bred to noninfected boars. the original herd is
disposed of as soon as the replacement unit has
grown to sufficient size

45. Brucella suis
(porcine type of Brucella)

Antimic ro bia l S us c e ptibility
B. suis is sensitive to = vitro to aminoglycosides,
rifampicin, and tetracyclines
clinical efficacy of antimicrobials = very low

46. Brucella
melitensis

47. Brucella melitensis
(Bacterium melitensis, caprine type of Brucella, Micrococcus melitensis)
=first isolated by Bruce in 1887 from the spleen of a
resident of the Island of Malta who had died of a
disease known as Malta fever or Mediterranean fever
= it is a disease of goats and sheep

Mo rpho lo g y a nd S ta ining
Re a c tio ns
= forms small rods that are so short that they are
mistaken to be a cocci
stains = same as B. abortus

48. Brucella melitensis
(Bacterium melitensis, caprine type of Brucella, Micrococcus melitensis)

Cultura l a nd Bio c he mic a l Fe a ture s
= does not require supplementary CO
2
for growth and
either does not produce H
2
S (does in trace amounts)
solid and liquid media of B. abortus = suitable for B.
melitensis
3 biotype = Biotype 1, 2, 3
Biotype 1 = the most common
Antig e ns
smooth cultures = have the A and M antigens or both
antigens together.

49. Brucella melitensis
(Bacterium melitensis, caprine type of Brucella, Micrococcus melitensis)

Epizo o tio lo g y a nd Pa tho g e ne s is
natural hosts = goats and sheep
other infected animals = pigs, cattle, camels, and
humans, feral animals including hares and impala
Goats = more susceptible than sheep
Source = ingestion of feed or water contaminated by
uterne and vaginal discharges from infected does
Milk = contains large numbers of this organisms
Pathogenecity = same as B. abortus in cows
B. melitensis = facultative intracellular parasite that
survives and multiplies within the phagocytic cells of
the reticuloendothelial system

50. Brucella melitensis
(Bacterium melitensis, caprine type of Brucella, Micrococcus melitensis)
Erythritol = the growth is stimulated
Extended bacteremia with fever = 5 to 10 weeks or
longer is followed by abortion storm (highly susceptible
goat herd or sheep flock)
Infected does = shows lameness, hygromas, and
mastitis
Billy goats = develops orchitis
Kid goats = can remain latently infected until sexually
mature
Immunity
Goats and sheep = develop effective protective
immune responses to this organism that eventually
clear the infection
Humoral antibody = appears about 2-3 weeks after
infection

51. Brucella melitensis
(Bacterium melitensis, caprine type of Brucella, Micrococcus melitensis)
Infected sheep = develop delayed hypersensitivity to
antigens of B. melitensis
live avirulent Rev 1 and strain 53H38 = vaccines used
to prevent and control B. melitensis
Rev 1 = more effective than 53H38; prevents abortion
and shedding of the organism; animals immunized by
this become serologically negative 6 months later.
disadvantage of this is that it may localize in the
placenta of pregnant does and cause abortion.
Localization in the mammary gland and shedding in
the milk also occur
53H38 = stimulates more persistent antibody response
then Rev 1

52. Brucella melitensis
(Bacterium melitensis, caprine type of Brucella, Micrococcus melitensis)
Dia g no s is
bacteriological methods = the same as those used to
detect brucellosis
phage sensitivity, agglutination with monospecific
antiserum, guniea pig inoculation = isolations may be
identified
complement fixation, agar-gel immunodiffusion, and
rose bengal plate test = serological tests that are
available and give comparable results with the classic
agglutination test
Whey test = can be performed also
Milk-ring test = not reliable on sheep milk
Intrapalpebral allergic test = more sensitive but slightly
less specific than serological assays for detection of
infection in sheep flocks

53. Brucella melitensis
(Bacterium melitensis, caprine type of Brucella, Micrococcus melitensis)

Antimic ro bia l S us c e ptibility
Aminoglycosides, rifampicin, and tetracyclines =
sesitive to B. melitensis
Efficacy of antimicrobials in therapy = has not been
reported

54. Brucella
neotomae

55. Brucella neotomae
= first isolated by Stroenner and Lockman from a
dessert wood rat (Neotoma lepida) trapped alive in the
Great Salt Dessert of Utah
= it has not been recovered from any other naturally
infected host
wood rat = well tolerated and upon experimental
infection it persist for at least a year without producing
significant lesions

56. Brucella
ovis

57. Brucella ovis
=causes epididymitis in rams
= early isolation in New Zealand and Australia
= produces late abortions in females and lowers flock
fertility

Mo rpho lo g y a nd S ta ining
Cha ra c te ris tic s
=acid fast under certain conditions of staining
korster staining method = it stains blue, not red

c ultura l a nd bio c he mic a l fe a ture s
=requires supplementary CO
2
for growth
= does not produce H
2S
=most strains are urease negative
= does not metabolized erythritol or other
carbohydrates

58. Brucella ovis
colonies = appear to be smooth, they are always in the
rough phase on primary isolation
= there are no biotypes
= the only species to show less than 100 percent DNA
homology with other species in the genus
Antig e ns
= it has an R surface antigen that cross reacts with
rough strains
= does not react with A or M antigens
= shares a large number of protein antigen with other
Brucella sp.

59. Brucella ovis

Epizo o tio lo g y a nd Pa tho g e ne s is
sheep = only natural hosts of B. ovis
British breeds = more susceptible than Merinos
rams = clinically affected much more frequently than
ewes
Transmission = venereal, and rams become infected
by mating with ewes previously covered by other
infected rams
ewes = developed placental infections with
subsequent abortion
Pasture = B. ovis can survive for a month or two
Route of natural infection = ingestion; rams can be
experimentally infected by the oral route as can ewes
in the early stages of pregnancy; rams as young as 4
months old can be come infected

60. Brucella ovis
clinical signs = transient, inapparent bacteremia with
subsequent localization of the organism in the
epididymis of the male. (tail of the epididymis is
affected often unilaterally). the ram may show no
clinical signs at this time but shed the organism in its
semen for a prolonged period .
epididymis = a permatocele forms and ruptures, and
finally spermatic granulomas form with later testicular
atrophy
Rams= have lowered fertility
Type 3 hypersensitivity responses = plays a role in the
pathogenesis of the epididymis because lesions in
experimentally challenged rams are more severe in
animals previously vaccinates than in non-vaccinated
controls.

61. Brucella ovis
Ewes = less susceptible to infection by B. ovis but
lesions occur. They vary from a superficial purulent
exudates on an intact chorioallantoic membrane to
advanced fibrosis and necrosis of this membrane
Lambs = organism is pathogenic to this in the utero,
but the fetus may survive in the presence of infection
Placentitis = interferes with fetal nutrition
Immunity
cell-mediated = immunological basis of the protective
immune response
*many rams that become infected do not develop
epididymitis
humoral antibodies = detectable in about 3-4 weeks
after infection, and delayed cutaneous hypersensitivity
to B. ovis antigens develops later
Vaccination of ewes = does not influence spread of
infection in a flock

62. Brucella ovis
vaccines = consists of saline oil adjuvant bacterins of
formalinized B. ovis or live B. melitensis Rev 1
B. ovis 7-26 = a live vaccine was shown to be effective
in 6-10 weeks old lambs (it was not transmitted to
unvaccinated sheep)
Vaccination of ewes = does not influence spread of
infection in a flock
Dia g no s is
=palpation of the testicles, culture of the semen, and
demonstration of antibodies in the serum
Palpation = is of limited value since many advanced
cases show no palpable lesions of the testes (enlarged
epididymis with testicular atrophy is valuable in
diagnosis)

63. Brucella ovis
culture of the semen = important adjunct to diagnosis
and has been facilitated by the use of selective media
modified for the growth of the organism
flourescent antibody test = use to detect the organism
in a semen smear
complement-fixation, ELISA, immunodiffusion, and
hemagglutination test = used for the detection of the
antibody in the serum
ELISA = less accurate and sensitive as the
complement-fixation test nad is easier to perform
complement-fixation test = rams are five times more
likely than ewes to be positive

64. Brucella ovis
Co ntro l
= depends on preventing spread of infection between
rams
Infected older rams = must kept separate from young
rams and the latter are used only on ewes known to
be free of infection
eradication of the disease = reacts in the complement-
fixation and ELISA

65. Brucella
canis

66. Brucella canis
(canine type of Brucella)
first isolation = in 1966 from outbreaks of abortion and
whelping failures among dogs in the US and Great
Britain
1968 = it was characterized and named Brucella canis
= highly adopted to domestic dogs
=not readily transmitted to other animals, although it
will infect humans.

Mo rpho lo g y a nd S ta ining re a c tio ns
=a small rod-shaped coccobacillus similar to other
Brucella sp.
Stains = similar to other Brucella sp.

67. Brucella canis
(canine type of Brucella)

Cultura l a nd Bio c he mic a l Fe a ture s
=produces only rough or mucoid colonies
= smooth phase has not been observed
= it is inhibited by 10 percent CO
2
Broth =growth becomes quite mucoid and a ropy,
viscous sediment is formed
=does not utilize erythritol as a preferred nutrient
=produces large amounts of urease
= does not form H
2
S.

68. Brucella canis
(canine type of Brucella)
Antig e ns
= it carries R but not A or M surface antigens
=species-specific antigen is associated with the
mucoid antigen shed by the organism
= cross-reactivity with Actinobacillus equuli,
Pseudomonas aeruginosa, and P. multicoda also
occur
= it has been found in breeding kennels, pet and stray
dogs, and in lkaboratory colonies of beagles
= infection appears to be more prevalent in stray dogs
than in pets
= 2-3 years age group had a higher prevalence of
seropositivity than did older dogs

69. Brucella canis
(canine type of Brucella)
Transmission = occurs principally at the time of
abortion, when may bacteria are shed in the persistent
vaginal discharge. it continues 4- 6 weeks after an
abortion
Male dogs = harbor the organism in their genital tracts,
from it shed intermittently (transmitted by coitus to the
female)
=after initial infection, bacteremia follows for 2 years.
= infected dogs do not show no clinical signs but some
do exhibit clinical signs have generalized
lymphadenitis, splenitis, and embryonic deaths and
abortions at approximately 50 days of gestation.
Infected males = have epididymitis, scrotal dermatitis,
and testicular atrophy.

70. Brucella canis
(canine type of Brucella)
Sperm agglutination in the semen, phagocytosis of
spermatozoa, delayed skin hypersensitivity to
testicular antigens = isoimmune responses to sperm
antigens plays a role in the pathogenesis of B. canis
infections and male fertility
*there is evidence that damage to epithelial cells of the
testes, epididymis, and prostate caused by B. canis
(triggers production of sperm antibody)

71. Brucella canis
(canine type of Brucella)
Immunity
cell-mediated = protective immune response of B.
canis
Humoral antibodies = appear at between 2-7 weeks
nad are present in highest concentration in bacteremic
animals
Titers = diminish with resolution of the bacteremia
*there is no successful vaccines against B. Canis
infection in dogs
B. ovis vaccines = can stimulate some resistance to B.
Canis, but this resistance is much inferior to that
observed dogs following recovery from B. canis
infection

72. Brucella canis
(canine type of Brucella)
Dia g no s is
*diagnosis is easy in animals that show clinical signs
of abortion and infertility (females) or epididymis
(males)
Clinical signs, direct culture of blood, lymph nodes, or
bone marrow; and serological test = are used in
diagnosis
mercaptoethanol, tube agglutination, complement-
fixation, counter immunoelectrophoresis, agar-gel
immunodiffusion, and a rapid
slide agglutination test = are not completely
standardized and are subject to occasional but
important "false-positives" and hard to interpret "low
titers" and to broad heterotypic reactivity shown by B.
canis antigens

73. Brucella canis
(canine type of Brucella)
Agar-gel immunodiffusion test = based on internal
antigens of B. canis is the most sensitive and accurate
serologic means of detecting infection.
Isolation of B. Canis in infected dogs = most certain
diagnostic method

Antimic ro bia l S us c e ptibility
Vitro to aminoglycosides, rifampicin, and tetracycline =
B. canis is sensitive *B. canis infection is unlikely to be
successful
aminocycline (25mg/lb twice daily) + streptomycin (25
mg/lb) = given by intramuscular injection for 7 days is
effective in curing only 3 out of 11 experimentally
infected dogs.

74. Brucellosis in
humans

75. Brucellosis (Undulant Fever) of Humans
= can be caused by B. abortus, B. canis, B. melitensis,
and B. suis (all biotypes)
=species involved is in great part determined by
opportunity for exposure
B. suis infection = common in swine belt (north central
of US)
B. abortus = southeastern US is found
B. melitensis = common in Mexico and in localized
areas of the southwestern part of US
=this species is also found with some frequency in the
midwestern states (where it is contracted from swine)
Caribou (North American reindeer Rangifer tarandus)
= brucellosis in humans have been derived in Alaska
infected with B. suis biotype 4

76. Brucellosis (Undulant Fever) of Humans
B. canis = many people were found to be infected with
this species ten years after it was isolated. Half were
laboratory personnel who were working with the
organism, and most of the owners of infected dogs
were infected
Cases of B. abortus and B. suis = usually seen in
veterinarians, farmers, slaughterhouse personnel, and
others connected to cattle and swine
*men are more susceptible than woman (2/3 of the
cases were men that was infected partly B. abortus
and partly B. suis infection)
direct contact = is more hazardous than drinking
infected milk (infections in men are more common
even in areas where the predominant type is B.
abortus)

77. Brucellosis (Undulant Fever) of Humans
20 and 45 years = age group that can have brucellosis
infants = who drinks milk is seldom become infected
although the disease has been diagnosed in children
as young as 4 years old
B. suis = more virulent for humans then B. abortus;
most often contracted by exposure to blood or tissue
fluids from infected swine in the slaughterhouse

78. Brucellosis (Undulant Fever) of Humans

Bruc e llo s is a s a n Oc c upa tio na l

Ha za rd fo r Ve te rina ria ns
brucellosis = poses a hazard to veterinarians in rural
practice because they often come in contact with
infected secretions
Blood test surveys = indicates that a comparatively
large percentage of veterinarians reacted positively,
although may had no clinical history of the disease
infection in veterinary colleges = was not uncommon
*the veterinarians who showed no evidence of
antibodies to brucella infection were either recent
graduates or involved in commerce, laboratory work,
or teaching.

79. Brucellosis (Undulant Fever) of Humans
practicing veterinarian = is exposed to more viable
Brucella organisms than other people in rural
communities. during the common procedure of
removing a retained placenta from a cow, the vet.
comes in intimate contact with the uterine discharges
rich in organisms that can enter his or her body
through the conjunctiva or the intact skin, or by
inhalation.
wounds on the hands = make ideal sites of entry
Accidental inoculation with B. abortus strain 1 9 =
major source of infection in vet in vaccinating cattle.
Veterinarians may jab the needle into his thigh or
scratch thumb.
strain19 = it usually does not cause chronic infections
in humans but can cause severe effects in those
previously infected with B. abortus

80. Brucellosis (Undulant Fever) of Humans
Dia g no s is
*the acute disease is frequently overlooked or
misdiagnosed.
*patients frequently decide they have influenza or
chills and then recover
acute stage = the disease may be misdiagnosed
because of its sporadic in nature and its vague signs
diagnosis = based on the patient's history, clinical
signs, isolation of the organism, and serological tests.
severe phase of the disease = individual is acutely ill,
suffers from prostration and weakness, develops daily
fever (afternoon and evening), suffers chills and night
sweats during which fever disappears only to have the
cycle recur on following days.

81. Brucellosis (Undulant Fever) of Humans
the acute symptoms usually lessen after a few days,
but , following an interval of varying length during
which the patient feels better, another period of acute
symptoms may appear. There may be several
remissions
intermittent fever = responsible for the name undulant
fever
Infections with B. melitensis and B. suis = are usually
more severe than those with B. abortus, but this is not
always the case.
*the mortality is low, but recovery from infections often
is very slow.
*many persons never fully recover from the effects of
this disease.

82. Brucellosis (Undulant Fever) of Humans
chronic cases = this form is more difficult to diagnose.
usually the patients suffers from great debility,
weakness, a low-grade remittent fever, and joint pains;
there may be sweating, lassitude and malaise,
gastritis, abdominal pain, skin rashes, headache,
irritability, depression, insomnia, arthritis, and
backache.
*patients may be labeled neurotic (complains are hard
to substantiate by laboratory test)

83. Brucellosis (Undulant Fever) of Humans
Melitococcic spondylitis = an adteoarticular
complication of brucellosis of humans in Italy
septic arthritis of the hip= came from B. suis
Brucella organisms = implicated cases of osteomyelitis
and diseases in the nervous system
blood culture = when positive, are diagnostic
isolation of the organism = from the blood is usually
difficult and often possible, particularly when the
offending organism is B. abortus
*Greater success is achieved in acute rather than in
chronic cases

84. Brucellosis (Undulant Fever) of Humans
Standard agglutination test, antiglobulin test, and the
complement-fixation test = three serological test used
in aid to diagnosis
Agglutination test = it has been used for years, but it
must be interpreted with great caution because it may
produce aberrant results, such as occasional
prozones, and "nonagglutination" antibodies may be
present, giving a negative test even in persons who
have had the disease for a long time; useful
particularly in recently acquired acute cases of
brucellosis
Antiglobulin test (Coomb's test) and complement
fixation test = are supplementary and are value in the
diagnosis of long-stranding brucellosis

85. Brucellosis (Undulant Fever) of Humans

Tre a tme nt
Tetracyclines = are recommended by FAO/WHO
Expert Committee on Brucellosis be given for 21 days
Tetracycline + streptomycin = must be given to severe
infection and for all B. suis infections
Chloramphenicol = is of value but urged caution in its
prolonged use.
*although these antibiotics often produce a good initial
clinical response, a large percentage of patients suffer
recurrence of the disease.

86. GenusBrucella