Title: Zoonosis
1Zoonosis
Yersinia
Brucella
2ZOONOSIS
A disease, primarily of animals, which is
transmitted to humans as a result of direct or
indirect contact with the infected animal
population
3Brucellosis
- Overview
- Morphology Physiology
- Epidemiology
- Symptoms
- Pathogenesis
- Diagnosis
- Treatment
4Brucella Overview
- Primarily a disease of animals.
- Common where significant disease among domestic
animals. - Common names- Undulant fever, Malta fever,
Mediterranean remittent fever. - Brucella can go through intact skin.
- Facultative intracellular bacteria
5Morphology Physiology
- Small gram-negative coccobacillus
- Grows slowly (7 days), at 370 C.
- On subculture, a minimum of 48 h growth
- Aerobic growth on Chocolate agar and Sheep blood
agar - Will not grow on MacConkey or Eosin methylene
blue (EMB) agar
6Morphology Physiology
- Non-pigmented and non-hemolytic
- Non-motile
- Oxidase positive
- Catalase positive
- Urease strongly positive, less than 2 hours.
Some species within 5 minutes.
7Microscopic Characteristics
- Brucella spp.
- poorly staining
- small gram-negative coccobacilli
- seen mostly as single cells
- appearing like fine sand
8Brucella melitensis colonies
A. Grows slowly on most standard laboratory
media. Usually not visible at 24h.
B. Pinpoint, smooth, translucent, non-hemolytic
at 48h.
9Public Health AspectsBrucella Sources
- Brucellosis caused by 1 of 4 Brucella species
- B. abortus
- Some strains
- require 5 CO2
- on initial
- isolation.
102. B. melitenus
Sheep
Camels
Goats
113. B. suis
124. B. canis
132 patient populations
- Individuals who work with unvaccinated animals
- B. abortus and B. suis
- Infections result from
- direct contact
- inhalation
- Individuals who ingest unpasteurized dairy
products - B. melitensis is the most common agent
14Host Animal - Brucellosis
- Asymptomatic or mild disease.
- Predilection for organs rich in erythritol
(breast, uterus, placenta, epididymis). - Causes sterility, abortions or carrier state in
non-human animals.
15Human - Brucellosis
16Human - Brucellosis
17Pathogenesis
Brucella
mucosal epithelium
Transported to lymph nodes, spleen, liver and
bone marrow.
18Pathogenesis
Lysozome
X
Phagosome
19Pathogenesis
- No exotoxin
- LPS does not activate the alternative complement
pathway - Acute lymphadenitis
- Granulocyte production in lymphatic tissue,
spleen, liver, bone marrow, lymph nodes and
kidneys. - A potential bioterrorist agent
20Diagnosis
- Symptoms and history
- Serological agglutination tests
- Culture
- Blood and bone marrow cultures
- Spleen, liver, joint fluid or abscesses
21Treatment
- Tetracycline, doxycycline, or
trimethoprimsulfamethoxazole in combination and
rifampin or gentamicin for 6 weeks to prevent
reoccurring infection.
22Tularemia (Francisella tularensis)
Gram stain
23Tularemia Overview
- Primary reservoir in US
- Rabbits and muskrats
- Insect vectors
- Ticks
- Infection via
- Insect bites
- Handling contaminated animal tissues
- Inhalation of aerosols
- Ingestion of contaminated food or water
- Exposure in a laboratory setting
24Tularemia Overview
- Gram-negative coccobacilli.
- Low infectious dose
- Two subspecies of F. tularensis
- subspecies tularensis (type A)
- subspecies holarctica (type B)
25Morphology Physiology
- Tiny gram-negative coccobacillus
- Nonmotile, encapsulated
- Aerobic slow growing (48 hours) 35-370 C
- Fastidious organism requires sulfhydryl
(cysteine, IsoVitaleX) supplementation for growth - Grows wells on
- Chocolate agar
- Buffered charcoal yeast extract agar
26Colony Characteristics
- After 48 hours incubation
- Colonies
- Very small
- white to gray to bluish-gray
- Will not grow on MacConkey or EMB plates.
F. tularensis on chocolate agar 48 hours growth.
27Microscopic Characteristics
Tiny, faintly staining, pleomorphic gram-negative
rods (0.2-0.5 mcm X 0.7-1.0 mcm) are noted cells
are smaller than those of Haemophilus species.
28Phenotypic Characteristics
- Grows slowly at 35-370 C
- Oxidase-negative
- Weakly catalase-positive (may be negative)
- Urea-negative
- Nitrate-negative
- Non-motile
- Beta-lactamase-positive
- Satellite or XV test-negative (unlike
Haemophilus)
29Tularemia Public Health
- Modes of humans infection
- Bite of infected flies, or ticks
- Handling contaminated animal tissues or fluids
- Direct contact with or ingestion of contaminated
water, food, or soil - Inhalation of infective aerosols (most likely BT
route)
30Tularemia Public Health
- Endemic in US
- Majority of cases occur May September (tick
exposure) or winter (hunters). - Most in rural areas.
- Arkansas, Missouri and Oklahoma
31Symptoms
- Incubation period 3-5 days (range 1-21 days)
- Clinical presentation can be divided into groups
- Ulceroglandular (45-85) /glandular (10 to 25)
- Typhoidal
- Pneumonic
- Oculoglandular
- Oropharyngeal/Gastrointestinal
- Prominent lymphadenopathy
- Recovery followed by permanent immunity
32Tularemia Clinical Types
- Clinical presentation based on the route of
infection
33Ulceroglandular Glandular tularemia
- Ulceroglandular accounts for 75-85 of naturally
occurring cases.
34Typhoidal tularemia
- Bacteremia- Sepsis
- Fever, chills, headache, myalgias, malaise, sore
throat, and anorexia. - Likely bioterrorism presentation.
35Pneumonic tularemia
- Entry into lungs via
- Aerosols
- hematogenous
- Severe atypical pneumonia
- Likely BT presentation
36Oropharyngeal tularemia
Oculoglandular tularemia
- Inoculation of the conjunctivae
- Unilateral, purulent conjunctivitis
- preauricular, submandibular or cervical
lymphadenopathy
- Primary disease is confined to the throat.
- Ingestion of infected meat or water can result in
orpharyngeal or gastrointestinal tularemia
37Pathogenesis
38Macrophages engulf F. tularensis within a
pseudopod loop
Daniel L. Clemens, Bai-Yu Lee, and Marcus A.
Horwitz. INFECTION AND IMMUNITY, Sept. 2005, p.
58925902
39- Facultative intracellular pathogen
- Capsule protects against complement killing
- Macrophage uptake
- bacterial surface polysaccharides
- serum complement
- complement C3 receptors
- LPS - O antigen
- prevents maturation of the phagosome
- multiply to high levels in cytosol
- Bacterial release via apoptosis
40Diagnosis
- Symptoms History
- Direct staining of clinical specimens with a
fluorescein-labeled antibodies. - Serum antibody titers of 1160 or greater
- Culture on cysteine-rich media
- Notify Laboratory personnel if you suspect
Francisella since it is HIGLY INFECTIOUS
41Treatment of Tularemia
- Prompt removal of ticks and insect repellent can
prevent disease. - Antibiotics
- Streptomycin is the drug of choice
42Yersinia
43Overview 3 species cause human disease
- Yersinia pestis
- Yersinia enterocolytica
- Yersinia pseudotuberculosis
44Overview Plague
- Yersinia pestis a gram-negative bacterium.
- Three forms of clinical illness
- Bubonic
- Septicemic
- Pneumonic
- Pneumonic is the only one transmitted through
aerosals.
45Plague Overview
- Natural disease of rodents
- Fleas that live on rodents transmit the bacteria
to humans, in the bubonic form. - This disease occurs in many areas of the world,
including the United States.
46Plague Overview
- U.S. averages 13 cases/yr (17 in 2006)
- Plague is endemic in the desert southwest.
- Most cases occur in summer.
47Microscopic Characteristics
- Y. pestis appear as single cells or short chains
of plump, gram-negative rods.
48Microscopic Characteristics
- Gram stain
- In direct smears, bacterial cells may be inside
or outside of leukocytes. - The Gram smear morphology is suggestive but not
specific for Y. pestis.
Bipolar staining of a plague smear prepared from
lymph aspirated from a bubo of plague patient.
49Microscopic Characteristics
- Bipolar staining occurs when using Wayson, or
Giemsa stain.
CDC
50Colony Characteristics
- Grows well on most standard laboratory media.
- Sheep Blood Agar
- Gray-white translucent colonies
- Pinpoint, gray-white, non-hemolytic at 24 hours
Blood agar plate of Yersinia pestis at 48 hours.
CDC/Dr. Brodsky
51Y. pestis Physiology
- Non-motile
- Pleomorphic gram-negative bacillus
- Urease, and oxidase negative
- Facultative anaerobe
- Optimal growth at 28o C
- Facultative intracellular parasite
52Public Health Aspects of Plague
- Fleas carry Y. pestis in their intestinal tract.
- When feeding the fleas regurgitate uncapsulated
organisms. - Bacteria re-encapsulate and grow.
- Progeny are resistant to intracellular killing
53Yersinia pestis life-cycle
54Plague - Clinical types
- Bubonic
- infected lymph nodes.
- Pneumonic (most likely BT presentation)
- transmissible by aerosol deadliest.
- Septicemic
- blood-borne organisms.
55Bubonic Plague
- Regional lymphadenitis (Buboes)
- Inguinal, axillary, or cervical lymph nodes most
common - 80 can become septic
- 60 mortality if untreated
- Cutaneous findings
- Possible papule, vesicle, or pustule at
inoculation site - Purpuric lesions - late
56Bubo
- swollen inguinal lymph node or bubo.
- After the incubation period of 2-7 days, symptoms
of the plague appear.
57Pneumonic Plague
- Pneumonic
- From aerosol or septicemic spread to lungs.
- Person-to-person transmission by respiratory
droplet. - 100 mortality untreated.
- Pneumonia progresses rapidly to dyspnea,
cyanosis. - Death from respiratory collapse/sepsis.
58Septicemic Plague
- Primary or secondary
- Secondary from bubonic or pneumonic forms
- 100 mortality if untreated
- Severe endotoxemia
- Systemic inflammatory response syndrome
- Shock, Disseminated intravascular coagulopathy
(DIC) - Adult Respiratory Distress Syndrome (ARDS)
59This patient presented with symptoms of plague
that included gangrene of the right hand causing
necrosis of the fingers. In this case, the
presence of systemically disseminated plague
bacteria Y. pestis, i.e. septicemia, predisposed
this patient to abnormal coagulation within the
blood vessels of his fingers.
60Y. pestis Virulence Determinants
- 3 virulence encoded Plasmids
- Virulence is up-regulated at 37C
- Capsule (F1 antigen)
61Yersinia Outer Proteins (Yops)
- 11 different proteins
- Antiphagocytic
- Inhibit production
- proinflammatory cytokines
- tumor necrosis factor
- Cytotoxin
62Yops
- Targets
- dendritic cells
- macrophages
- Neutrophils
- does not target B and T lymphocytes
63F-1 Antigen
- Glycoprotein capsule expressed at 370 C
- Not expressed in flea host
- Antiphagocytic
- Antibodies to F-1 are protective
64Plasminogen activator (fibrinolysin) and Coagulase
- Plasmid encoded proteins
- Promote dissemination of organisms from the clot
at the bite site - Coagulase is produced at 280 C but not at 320 C.
65Diagnosis
- Examination of Bubo aspirate, blood, sputum
- stained for bipolar staining
- Fluorescent-antibody
- Culture (hazardous)
66Plague Treatment
- Y. pestis is susceptible to a variety of
antibiotics. - streptomycin, tetracycline, and doxycycline
- Peumonic plague is contageous and isolation is
recommended.
67Clinical Case
- 30 year old man from Colorado, went to a hospital
emergency department with a 3-day history of
fever, nausea, vomiting, and right inguinal
lymphadenopathy. - Patient was not a hunter nor had he been in the
woods recently but he did have dogs. - He was discharged home without treatment.
68- Three days later, the man returned and was
hospitalized with sepsis and bilateral pulmonary
infiltrates. - One of the patient's dogs had serologic evidence
of past Y. pestis infection. - Cultures of blood and a lymph node aspirate.