Brucella spp. Flashcards
Characteristics
Gram-negative, small rods and coccobacili, non-motile
Facultative intracellular bact
Zoonosis
Biochemical test
Produce oxidase, catalase, nitrate reductase and urease (except B. ovis), utilize glucose as an energy sources=
Epidemiology
Agent & Usual Host
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
Epidemiology
Environment
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.
Virulence factor
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
Brucella abortus
Host and affect what organ
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.
Brucella abortus
Transmission
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
-Brucella abortus
CS
Abortion (during or after 5th month of gestation)
Birth of weak calves
Retained placenta
Brucella melitensis
Host
Sheep and goats
Most virulent species in cases of human
Brucella melitensis
Transmission
Sexual, contact with contaminated genital discharges and ingestion of raw milk
Brucella melitensis
Clinical signs
Abortion, mastitis, lameness and orchitis
Remain as carrier after recovers from infection
Brucella suis
Host
Swine and human
Brucella suis
clinical signs + organs affected
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
Brucella canis
Host
Dogs
Brucella canis
TRANSMISSION
ingestion or inhalation of organism aerosolized from aborted fetuses, vaginal discharge, milk, semen or urine
Brucella canis
cs/EFFECTS
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
Clinical signs in humans
Undulant fever, muscular pain, sweating, headache & weakness, orchitis
Lab diagnosis (1)
Direct examination with acid fast stain (resist decolorization with mild acids)
Lab diagnosis
Bacetrial culture
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
Lab diagnosis
MILK SAMPLES
Brucella milk ring test (BRT)
Lab diagnosis
serum samples
Rose-bengal plate test (BRT) - agglutinization
CFT
TAT - clear solution
Colony morphology
small and nonhemolytic
Treatment
antibiotics: tetracyline, streptomycin, rifampin
suspected usually euthanized or slaughtered
Prevention and control
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
