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Introduction
1. Anatomy
2. Microbiology
2.1 General bacteriology
2.2 Introduction to systemic bacteriology
2.3 Gram positive cocci
2.4 Gram negative cocci
2.5 Gram positive bacilli
2.6 Gram negative bacilli
2.7 Other important bacteria
2.7.1 Overview
2.7.2 Helicobacter pylori
2.7.3 Campylobacter jejuni
2.7.4 Haemophilus influenzae
2.7.5 Bordetella pertussis
2.7.6 Legionella pneumophila
2.7.7 Brucella
2.7.8 Mycobacteria
2.7.9 Actinomycetes
2.7.10 Nocardia
2.7.11 Mycoplasma pneumoniae
2.7.12 Treponema pallidum
2.7.13 Borrelia burgdorferi
2.7.14 Chlamydia / Chlamydophila
2.7.15 Rickettsia
2.7.16 Coxiella burnetii
2.7.17 Additional information
2.8 Virology
2.9 Parasitology
2.10 Mycology
3. Physiology
4. Pathology
5. Pharmacology
6. Immunology
7. Biochemistry
8. Cell and molecular biology
9. Biostatistics and epidemiology
10. Genetics
11. Behavioral science
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2.7.7 Brucella
Achievable USMLE/1
2. Microbiology
2.7. Other important bacteria

Brucella

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It causes brucellosis, a zoonosis (an infection acquired from animals). Brucella are Gram-negative coccobacilli, non-motile, and non-capsulated. The important species are B. abortus, B. melitensis, and B. suis. Brucellosis is also called Malta fever, undulant fever, or Mediterranean fever.

People who have close contact with animals, such as farmers and veterinarians, are at higher risk. Contaminated food, especially unpasteurized dairy products, is a common source of infection.

It typically presents as PUO (pyrexia of unknown origin) with:

  • Undulating fever (the temperature rises, then falls, and the cycle repeats)
  • Joint pain
  • Osteomyelitis
  • Lymphadenopathy
  • Sometimes hepatosplenomegaly

For diagnosis, samples can be collected from blood, bone marrow, urine, or lymph node biopsy. The organism is isolated faster on special media such as trypticase soy agar, serum dextrose agar, Castaneda’s medium, and BACTEC blood culture, incubated under 10% CO2.

To detect antibodies, you can use:

  • ELISA
  • Complement fixation tests
  • Agglutination tests

The milk ring test is used to detect animal brucellosis.

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