BRUCELLA

Sharq Elneil College

School of Medical Laboratory Sciences Department of Microbiology

Medical Bacteriology course

Mr.Mahadi Hassan Mahmoud Bsc, Msc, MIBMS Microbiology

Historical Background

1897 A.E. Wright ; pathologist in British

army - developed agglutination test.

What is the source?

“Mediterranean Fever Commission” 1904

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.

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

Historical Background

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

Important species

B. melitensis >> goats & sheep

B. abortus >> cattle

B. suis >> pigs

Important: All 3 species can infect man and domestic animals

Brucella species gram-negative bacilli

Brucella abortus

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.

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.

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

Brucella melitensis colonies

2. Serological Tests

Standard agglutination test

Mercaptoethanol test

Complement fixation test

Coobs’ test

3. Brucellin Skin Test

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

Biochemical tests

Gram stain: Gram negative cocco bacilli

Biochemicals:

Catalase

Oxidase

Dye inhibition test

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

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

Prognosis

Preantibiotic era

Mortality 2% mainly endocarditis

Morbidity

High with B. melitensis

Nerve deafness

Spinal cord damage

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.

THANK YOU FOR ATTENTION