UTS 3.Zonosis 1

8/14/2019 UTS 3.Zonosis 1

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Zoonosis

Francisella

Brucella

Yersinia


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ZOONOSIS

A disease, primarily of animals, which

is transmitted to humans as a result ofdirect or indirect contact with the

infected animal population


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Brucellosis

1. Overview

2. Morphology &

Physiology

3. Epidemiology

4. Symptoms

5. Pathogenesis

6. Diagnosis

7. Treatment


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Brucella: Overview

Primarily a disease of animals.

Common where significant disease among

domestic animals.

Common names- Undulant fever, Maltafever, Mediterranean remittent fever.

Brucella can go through intact skin.

Facultative intracellular bacteria


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Morphology & Physiology

Small gram-negativecoccobacillus

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 methyleneblue (EMB) agar


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Non-pigmented and non-hemolytic

Non-motile

Oxidase: positive

Catalase: positive

Urease: strongly positive, less than 2 hours. Some

species within 5 minutes.


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Microscopic Characteristics

Brucellaspp.

poorly staining

small gram-negativecoccobacilli

seen mostly as single cells

appearing like fine sand


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Brucella melitensiscolonies

A. Grows slowly on

most standard

laboratory media.

Usually not visible

at 24h.

B. Pinpoint,

smooth,

translucent, non-

hemolytic at 48h.


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Public Health Aspects

Brucella: Sources

Brucellosis caused by 1 of 4Brucellaspecies:

1. B. abortus

Some strainsrequire 5% CO2on initial

isolation.


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2. B. melitenus

Goats

Sheep

Camels


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3. B. su is


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4. B. canis


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2 patient populations

1. Individuals who work

with unvaccinated

animals

B. abortus and B. suis

Infections result from:

direct contact inhalation

2. Individuals who ingest

unpasteurized dairy

products

B. melitensis is the most

common agent


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Host 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.


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Human - Brucellosis

Symptoms

AcutePhase AdvancedDisease

ChronicForm


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Organism Animal

reservoir

Human disease Complications

B. abortus Cattle mild suppurative febrile

infection

Rare

B. canis Dogs mild suppurative febrileinfection Rare

B. suis Swine Prolonged disease with

destructive lesions of the

lymphoreticular organs and

kidney

B. melitensis goats/sheep Severe and recurring disease High incidence of

serious

complications

Human - Brucellosis


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Pathogenesis

mucosal epithelium

Transported to lymph nodes,spleen, liver and bone marrow.

Brucella


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Pathogenesis

Phagosome

Lysozome

X


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Pathogenesis

No exotoxin

LPS does not activate the alternativecomplement pathway

Acute lymphadenitis

Granulocyte production in lymphatic tissue,

spleen, liver, bone marrow, lymph nodes andkidneys.

A potential bioterrorist agent


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Treatment

Tetracycline, doxycycline, or

trimethoprimsulfamethoxazole in combination

and rifampin or gentamicin for 6 weeks to preventreoccurring infection.


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Tularemia:

(Franc isel la tularens is)

Gram stain


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Tularemia: 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


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Tularemia: Overview

Gram-negative coccobacilli.

Low infectious dose

Two subspecies of F . tularensis:

subspecies tularensis (type A)

subspecies holarctica (type B)


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Tiny gram-negative coccobacillus

Nonmotile, encapsulated

Aerobic slow growing (48 hours) 35-370C

Fastidious organism requires sulfhydryl (cysteine,IsoVitaleX) supplementation for growth

Grows wells on

Chocolate agar Buffered charcoal yeast extract agar


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Colony 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.


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Tiny, faintly staining, pleomorphic gram-negative rods

(0.2-0.5 mcm X 0.7-1.0 mcm) are noted; cells are smallerthan those of Haemophiluss ecies.


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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)

Phenotypic Characteristics


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Tularemia: Public Health

Modes of humans infection

Bite of infected flies, or ticks

Handling contaminated animal tissues or fluids

Direct contact with or ingestion of contaminatedwater, food, or soil

Inhalation of infective aerosols (most likely BT

route)
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Endemic in US

Majority of cases occur MaySeptember (tick

exposure) or winter (hunters).

Most in rural areas.

Arkansas, Missouri and Oklahoma

Tularemia: Public Health


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Symptoms

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


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Tularemia Clinical Types

Clinical presentation based on theroute of infection


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Ulceroglandular & Glandular tularemia

Ulceroglandular accounts for 75-85% of naturally occurring cases.


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Typhoidal tularemia

Bacteremia- Sepsis

Fever, chills, headache, myalgias, malaise,

sore throat, and anorexia.

Likely bioterrorism presentation.


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Pneumonic tularemia

Entry into lungs via

Aerosols

hematogenous

Severe atypical pneumonia

Likely BT presentation


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Oropharyngeal tularemia Primary disease is confined to the

throat.

Ingestion of infected meat or water

can result in orpharyngeal or

gastrointestinal tularemia

Oculoglandular tularemia

Inoculation of the conjunctivae

Unilateral, purulent conjunctivitis

preauricular, submandibular or cervical lymphadenopathy
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Pathogenesis


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Daniel L. Clemens,* Bai-Yu Lee, and Marcus A. Horwitz.

INFECTION AND IMMUNITY, Sept. 2005, p. 58925902

Macrophages engulf F. tularensis within

a pseudopod loop


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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


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Diagnosis

Symptoms & History

Direct staining of clinical specimens with a

fluorescein-labeled antibodies. Serum antibody titers of 1:160 or greater

Culture on cysteine-rich media

Notify Laboratory personnel if you suspectFrancisellasince it is HIGLY INFECTIOUS


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Treatment of Tularemia

Prompt removal of ticks and insect repellent can

prevent disease.

Antibiotics

Streptomycin is the drug of choice


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Yersinia


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Overview: 3species cause

human disease

Yersinia pestis

Yersinia enterocolytica

Yersinia pseudotuberculosis


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Overview: Plague

Yersinia pestis; a gram-negative bacterium.

Three forms of clinical illness;

Bubonic

Septicemic

Pneumonic

Pneumonic is the only one transmittedthrough aerosals.


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Plague: 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.


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Y. pestisappear as

single cells or short

chains of plump,gram-negative rods.


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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.


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Bipolar staining

occurs when usingWayson, or

Giemsa stain.

CDC

C l Ch i i


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Colony Characteristics

Grows well on most

standard laboratory

media.

Sheep Blood Agar

Gray-white

translucent colonies

Pinpoint, gray-

white, non-hemolytic

at 24 hoursBlood agar plate of Yersinia pestisat 48 hours.

CDC/Dr. Brodsky


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Non-motile

Pleomorphic gram-negative bacillus

Urease, and oxidase negative

Facultative anaerobe

Optimal growth at 28o C

Facultative intracellular parasite

Y. pestis: Physiology


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Public Health Aspects of Plague

Fleas carry Y. pestisin their intestinal tract.

When feeding the fleas regurgitate uncapsulated

organisms.

Bacteria re-encapsulate and grow.

Progeny are resistant to intracellular killing


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Yersinia pestis life-cycle
http://www.kcom.edu/faculty/chamberlain/Website/lectures/lecture/image/plague4.jpg


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Plague - Clinical types

Bubonic

infected lymph nodes.

Pneumonic (most likely BT presentation)

transmissible by aerosol; deadliest.

Septicemic blood-borne organisms.


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Bubonic Plague

Regional lymphadenitis (Buboes)

Inguinal, axillary, or cervical lymph nodes mostcommon

80% can become septic

60% mortality if untreated

Cutaneous findings

Possible papule, vesicle, or pustule at inoculation site

Purpuric lesions - late


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Bubo swollen inguinal lymph node or bubo.

After the incubation period of 2-7 days, symptoms

of the plague appear.


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Pneumonic Plague

Pneumonic

From aerosol or septicemic spread to lungs.

Person-to-person transmission by respiratorydroplet.

100% mortality untreated.

Pneumonia progresses rapidly to dyspnea,cyanosis.

Death from respiratory collapse/sepsis.


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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)

Septicemic Plague


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This 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.


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Y. pestis:Virulence Determinants

3 virulence encoded Plasmids

Virulence is up-regulated at 37C

Capsule (F1 antigen)

Yersinia Outer Proteins


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Yersinia Outer Proteins

(Yops)

11 different proteins

Antiphagocytic

Inhibit production

proinflammatory cytokines tumor necrosis factor

Cytotoxin

Y


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Yops Targets

dendritic cells

macrophages

Neutrophils

does not target B and T lymphocytes


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F-1 Antigen

Glycoprotein capsule expressed at 370C

Not expressed in flea host

Antiphagocytic

Antibodies to F-1 are protective


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Plasminogen activator

(fibrinolysin) and Coagulase

Plasmid encoded proteins

Promote dissemination of organisms from the clotat the bite site

Coagulase is produced at 280C but not at 320C.


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Diagnosis

Examination of Bubo

aspirate, blood, sputum

stained for bipolar staining

Fluorescent-antibody

Culture (hazardous)


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Plague Treatment

Y. pestisis susceptible to a variety of

antibiotics.

streptomycin, tetracycline, and doxycycline

Peumonic plague is contageous and

isolation is recommended.


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Clinical Case

30 year old man from Colorado, went to ahospital 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.


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Three days later, the man returned and

was hospitalized with sepsisand bilateral

pulmonary infiltrates.

One of the patient's dogs had serologicevidence of past Y. pestis infection.

Cultures of blood and a lymph nodeaspirate.

UTS 3.Zonosis 1

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