1. Brucella Six species of Brucella
B.melitensis, B.abortus, B.suis, B.canis
Sir David Bruce [brucellosis], Bernhard Bang [Bang's disease]
Undulant fever, Malta fever, Mediterranean remittent fever

2. Brucella
small (0.5 × 0.6 to 1.5 μm), nonmotile, nonencapsulated, gram-negative coccobacilli
grows slowly
strictly aerobic
does not ferment carbohydrates

3. Brucella endotoxin is less toxic intracellular parasite
the organisms are phagocytosed by macrophages and monocytes
phagocytosed bacteria are carried to the spleen, liver, bone marrow, lymph nodes
the bacteria secrete proteins that induce granuloma formation

4. Brucella
Intracellular pathogen that is resistant to killing in serum and by phagocytes
Smooth colonies associated with virulence
goats and sheep (Brucella melitensis)
cattle (Brucella abortus)
swine (Brucella suis)
dogs, foxes (Brucella canis)

6. Brucella
Latin America, Africa, the Mediterranean basin, the Middle East, and Western Asia
More than 500,000 documented cases
Vaccination of animals
Direct contact with the organism (e.g., a laboratory exposure), ingestion (e.g., consumption of contaminated food products), or inhalation

7. Brucella
Brucella causes mild or asymptomatic disease in the natural host
Erythritol (breast, uterus, placenta)
Brucellae are shed in high numbers in milk, urine, and birth products
B.melitensis is the most common spp

8. Brucella-Clinical diseases
Brucellosis: Initial nonspecific symptoms of malaise, chills, sweats, fatigue, myalgias, weight loss, arthralgias, and fever; can be intermittent (undulant fever)
can progress to systemic involvement (gastrointestinal tract, bones or joints, respiratory tract, other organs)

9. Brucella-Clinical diseases
Incubation period 1-6 weeks
Fever rises in the afternoon
Falling at night by drenching sweat
Lymph nodes enlarge, SM
Hepatitis, steomyelitis
Generalized infection subsides usually
A chronic state may occur

10. Brucella-Diagnosis grow slowly most enriched blood agars
microscopic and colonial morphology
positive oxidase and urease reactions
B. abortus and B. melitensis, B. abortus, and B. suis will react with antisera prepared against B. abortus or B. melitensis

11. Brucella-Serology IgM, IgG, IgA
Four fold increase or 1/80 indicate active infection
If agglutination negative “blocking antibodies” add antihumanglobulin

12. Brucella-Treatment Doxycycline+rifampin
Trimethoprim-sulfamethoxazole for pregnant women and for children younger than 8 years
6 weeks or longer
Fluoroquinolones, macrolides, penicillins, and cephalosporins either ineffective or have unpredictable activity.

13. Francisella
Two species, Francisella tularensis and Francisella philomiragia
the causative agent of tularemia (also called glandular fever, rabbit fever, tick fever, and deer fly fever) in animals and humans

14. very small (0.2 × 0.2 to 0.7 μm), faintly staining, gram-negative coccobacillus
nonmotile
thin lipid capsule
fastidious requirements (most strains require cysteine for growth)
strictly aerobic and requires 3 or more days

15. Gram stain of Francisella tularensis isolated in culture; note the extremely small coccobacilli

16. Antiphagocytic capsule
Intracellular pathogen resistant to killing in serum and by phagocytes
Wild mammals, domestic animals, birds, fish, and blood-sucking arthropods are reservoirs; rabbits and hard ticks are most common hosts; humans are accidental hosts
Worldwide distribution
The infectious dose is very small

17. Human tularemia is acquired most often from the bite of an infected "hard-shell" tick (e.g., Ixodes, Dermacentor, Ambylomma spp.)
or from contact with an infected animal or domestic pet
F. tularensis requires as few as 10 organisms when exposure is by an arthropod bite

18. Ulceroglandular tularemia: Painful papule develops at the site of inoculation that progresses to ulceration; localized lymphadenopathy
Oculoglandular tularemia: Following inoculation into the eye (e.g., rubbing eye with a contaminated finger), painful conjunctivitis develops with regional lymphadenopathy
Pneumonic tularemia: Pneumonitis with signs of sepsis develops rapidly after exposure to contaminated aerosols; high mortality unless promptly diagnosed and treated

19. Ulceroglandular tularemia is the most common manifestation

20. Francisella-Diagnosis
F. tularensis are hazardous for both the physician and the laboratory worker
Microscopy is insensitive due yo small size and faintly staining
Fluorescein-labeled antibodies
PCR
F. tularensis can grow on chocolate agar or buffered charcoal yeast extract (BCYE) agar, media supplemented with cysteine
a fourfold or greater increase in the titer of antibodies during the illness or a single titer of 1:160 or greater