1. Sharq Elneil College
School of Medical Laboratory Sciences
Department of Microbiology
Medical Bacteriology course
BRUCELLA
Mr.Mahadi Hassan Mahmoud
Bsc, Msc, MIBMS Microbiology

2. Historical Background
 1897 A.E. Wright ; pathologist in British
army - developed agglutination test.
What is the source?
“Mediterranean Fever
Commission” 1904

3. Historical Background
 1905 Zammit; Maltese physician
- Goats were the source of infection.
 1897 E. Bang; Danish veterinarian
-described intracelular pathogen causing
abortion in cattle named “Bacillus
abortus”.
 1918 A. Evans; American microbiologist
-made the connection between Bacillus
abortus and micrococcus melitensis &
named it Bacteriaceae.

4. Historical Background
 1920 Meyer and Shaw suggested
BRUCELLA
 1914 Mohler isolated organism from
liver & spleen of Pigs--B.suis.
 1957 B. neotome, 1963 B. ovis, 1966
B. canis

5.  Aerobic, Gram-negative bacilli
 Appear as cocci, coccobacilli and short
bacilli
 Non-motile, non-capsulate
 Optimum temp. >> 37oC
 Facultative intracellular parasites
 Essentially pathogens of goats, Cattle,
sheep and pigs
 Causative agents of Brucellosis
(typical zoonosis) worldwide
 Also known as Malta, Mediterranean or
undulant fever

6.  Important species
 B. melitensis >> goats & sheep
 B. abortus >> cattle
 B. suis >> pigs
 Important: All 3 species can infect
man and domestic animals

7. Brucella species
gram-negative bacilli

8. Brucella abortus

9. Transmission
 Zoonosis affecting domestic animals.
 Concentrated in milk, urine, genital organs.
ROUTES OF TRANSMISSION
 Oral : unpasteurised milk & products
raw milk or meet.
 Respiratory: lab workers.
 Skin: accidental penetration or abrasion
 - at risk farmers & veterinarians.
 Other routes:
Conjunctival, Blood transfusion,
Transplacental, ? person to person.

10. PATHOGENESIS
 Incubation period: 10-30 days
 Symptoms may be delayed for months
 Enter the body through:
 Skin abrasions, mucous membranes of the
alimentary or respiratory tracts and
sometimes the conjunctivae>> reach the
blood through regional lymphatics.
 Symptoms may vary without the fluctuating
temperature to act as guide.
 Bacteria localize in various parts of the
reticulo-endothelial system resulting in
complications in any part of the body.
 Symptoms include: malaise, low-grade fever,
lassitude, insomnia, irritability and swelling
around the joints.

11. LABORATORY DIAGNOSIS
1. Blood Culture
 Specimen
 Blood (10 ml volumes)
 Inoculate
 Blood culture tubes or bottles
(glucose-serum broth)
 Incubate in 10% CO2
 Cultures should be retained for at least
6-8 weeks before being discarded as
negative

12. Brucella melitensis colonies

13. 2. Serological Tests
 Standard agglutination test
 Mercaptoethanol test
 Complement fixation test
 Coobs’ test
3. Brucellin Skin Test

14.  Laboratory
 WBC (N) or . monocytosis
 ESR of little help
 Blood cultures
 slow growth = 4 weeks
 new automated system BATEC
identifies he organism 4-8 days
 more recent (BACT/ALERT) - 2.8 days
 PCR

15. Biochemical tests
 Gram stain: Gram negative
cocco bacilli
 Biochemicals:
 Catalase
 Oxidase
 Dye inhibition test

16. Laboratory Diagnosis
 Serology
 Main laboratory method of
diagnosis
 Serum agglutination test -
most widely used
measures agglutination for
IgG, IgM, IgA
2ME - break sulf-hydrile bonds
in IgM polymer - no
agglutination

17. which level is diagnostic ??
1 : 160 - non endemic area
1 : 320 - endemic area
SAT - false negative
 Prozone
 Blocking antibodies
 Other tests: coombs, ELISA,
CFT, FTA

18. Prognosis
 Preantibiotic era
 Mortality 2% mainly
endocarditis
 Morbidity
 High with B. melitensis
 Nerve deafness
 Spinal cord damage

19. Antimiocrobial S.T
 Combination of streptomycin and
tetracycline or rifampicin and
doxycycline
 Vaccination of young cattle (6-8
months)
 Pasteurization of milk or milk
products
 Eradication by compulsory testing
animals and slaughtering positive
reactors.

20. THANK YOU FOR ATTENTION