Brucella spp.

Question 1

Characteristics

Answer 1

Gram-negative, small rods and coccobacili, non-motile
Facultative intracellular bact
Zoonosis

Question 2

Biochemical test

Answer 2

Produce oxidase, catalase, nitrate reductase and urease (except B. ovis), utilize glucose as an energy sources=

Question 3

Epidemiology
Agent & Usual Host

Answer 3

B. abortus - cattle
B. melitensis - goat/sheep
B. suis - pigs
B. canis - dog

Agent resides in side cells of reticuloendothelial system spleen, liver, suprammamary lymph nodes or bone marrow) and reproductive tract

Cause abortion and sterility in domestic animals

Question 4

Epidemiology
Environment

Answer 4

At 0 Celsius, remain viable in carcasses and tissue for up to 6 months
Susceptible to many disinfectant - 70% ethanol and formaldehyde etc

Killed by moist heat (121 celcius , 15 mins) and by dry heat (160-170%, 1 hour)

High numbers of bacteria are shed in urine, milk, vaginal discharge, semen, and the products of birth.

Question 5

Virulence factor

Answer 5

Lipopolysaccharides
Virulence regulator proteins
Invasion of host cell
Avoid elimination by the host
Survive and proliferate within its replicative vacuole
Enable to escape from detection by the host immune system

Question 6

Brucella abortus

Host and affect what organ

Answer 6

Bovine, primarily cow
Bull - localizes in the testicle, resulting in unilateral orchitis, epididymitis, and inflammation of the accessory reproductive organ with decrease libido and impaired fertility (basically affect semen)

Cow -localized in udder, endometrium, and associated lymph nodes.

Question 7

Brucella abortus

Transmission

Answer 7

Healthy calves may become carriers - threat to herd and human (ingested contaminated milk in neonatal period)

Shed in large numbers in the afterbirth, placental fluids, aborted fetus and vaginal discharge

Lick aborted fetus or aborted fetus

Question 8

-Brucella abortus

CS

Answer 8

Abortion (during or after 5th month of gestation)

Birth of weak calves

Retained placenta

Question 9

Brucella melitensis

Host

Answer 9

Sheep and goats
Most virulent species in cases of human

Question 10

Brucella melitensis

Transmission

Answer 10

Sexual, contact with contaminated genital discharges and ingestion of raw milk

Question 11

Brucella melitensis

Clinical signs

Answer 11

Abortion, mastitis, lameness and orchitis

Remain as carrier after recovers from infection

Question 12

Brucella suis

Host

Answer 12

Swine and human

Question 13

Brucella suis

clinical signs + organs affected

Answer 13

bacteremia localized in bones, joints, reproductive tract and reticuloendothelial system

abortion between 4th to 12th week of gestation. Aborted placenta are usually edematous, hemorrhagic and covered with yellowish brown exudates

Preceding pregnancies may result in birth of weak , stillborn or mummified piglets

Question 14

Brucella canis

Host

Answer 14

Dogs

Question 15

Brucella canis

TRANSMISSION

Answer 15

ingestion or inhalation of organism aerosolized from aborted fetuses, vaginal discharge, milk, semen or urine

Question 16

Brucella canis

cs/EFFECTS

Answer 16

Female - early embryonic death or abortion (colonized in uterine epithelial cells of pregnant bitch), in non-pregnant, no cs but still shed bacteria in salivary, nasal or vaginal secretion

Male - infertility, epidymitis, orchitis, brucellae shed in urine

Anterior uveitis, osteomyelitis, discospondylitis, meningitis, pyogranulomatous, dermatitis and glomerulonephritis

Question 17

Clinical signs in humans

Answer 17

Undulant fever, muscular pain, sweating, headache & weakness, orchitis

Question 18

Lab diagnosis (1)

Answer 18

Direct examination with acid fast stain (resist decolorization with mild acids)

Question 19

Lab diagnosis
Bacetrial culture

Answer 19

Take specimens from fetal tissues, placenta, lymph nodes, vaginal discharge, semen, urine, bone marrow, blood

Need specific growth requirements (amino acids, nicotinamide, thiamine & magnesium)

8-10% Co2 , at 37 Celsius for 14 days

Question 20

Lab diagnosis

MILK SAMPLES

Answer 20

Brucella milk ring test (BRT)

Question 21

Lab diagnosis

serum samples

Answer 21

Rose-bengal plate test (BRT) - agglutinization
CFT
TAT - clear solution

Question 22

Colony morphology

Answer 22

small and nonhemolytic

Question 23

Treatment

Answer 23

antibiotics: tetracyline, streptomycin, rifampin

suspected usually euthanized or slaughtered

Question 24

Prevention and control

Answer 24

Testing and elimination of infected
Milk is screened periodically by MRT for antibodies to brucellae
Vaccines - Strain-19 vaccine and RB-51 for cattle, RV-1 for sheep