PetriKey

Bacterium

Brucella species

Undulant fever, unpasteurized dairy zoonosis

broo-SEL-uh

Gram negativegram-negativecoccobacilluszoonosisintracellularoccupationalfoodborne

High-yield clue

Undulant (relapsing) fever from unpasteurized dairy or livestock exposure is the classic brucellosis study clue.

Overview

Small Gram-negative coccobacilli that are facultative intracellular pathogens causing brucellosis (undulant fever), classically from unpasteurized dairy and occupational animal contact.

Classification

  • Gram-negative
  • Coccobacillus
  • Brucellaceae
  • Aerobe
  • Facultative intracellular

Lab & identification clues

  • Slow-growing, fastidious vocabulary
  • Facultative intracellular survival concept
  • Serology-based identification vocabulary
  • Select-agent handling framing (concept-level)

Associations

  • Unpasteurized dairy and animal-product transmission vocabulary
  • Farmers, veterinarians, abattoir occupational risk
  • Undulant fever and osteoarticular presentation vocabulary

Commonly confused with

  • Francisella tularensis
  • Coxiella burnetii

Your notes

Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.

OpenStax: Microbiology 2e organism classification foundationssourceNCBI Bookshelf: Medical Microbiology organism chapterssourceCDC: CDC disease and public-health topic pagessource