Zoonosis

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Zoonosis
Listeria monocytogenes
Bacillus
Erysipelothrix
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Listeria monocytogenes
http//textbookofbacteriology.net/Listeria.html
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Listeria

1. Overview
2. Bacteriological identification
3. Sources of Listeriosis
4. Pathogenic Mechanisms
5. Treatment

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Overview

• 3 categores of listeriosis
• Adult Disease
• Disease in pregnant women
• Fetal Disease
• 1 Human pathogenic species
• L. monocytogenes

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L. monocytogenes

• Gram positive coccobacilli in pairs or short
  chains
• Facultative anaerobe
• Facultative intracellular pathogen
• Motile (end-to-end tumbling) at 250 C not at 370
  C
• Weakly ß-hemolytic on sheep blood agar
• Can grow and replicate at 40 C and in high salt
  concentration.

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Sources of listeriosis

• Humans can be intestinal carriers (1-5)
• Found in a feces of mammalian, avian, fish and
  crustacean species
• Isolated from soil, silage, and other
  environmental sources
• Food sources raw vegetables, unpasteurized milk,
  fresh soft cheese, and meats
• Nosocomial transmission (neonatal nurses)

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Susceptible Populations

• Elderly and Immunocompromised
• Pregnant women
• Neonates

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Listeriosis in the Normal Adult
Soil
Food
Ingestion
Large Intestine
Small Intestine
Liver Spleen
Immune Response
Recovery
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Listeriosis in Normal Adult

• Acute febrile gastroenteritis
• Symptoms included body aches, fever, headache,
  diarrhea, and vomiting
• Illness 24 h after ingestion of bacteria and
  usually lasts 2 days. Common symptoms include
  fever, watery diarrhea, nausea, headache, and
  pains in joints and muscles.
• L. monocytogenes should be considered to be a
  possible etiology in outbreaks of febrile
  gastroenteritis when routine cultures fail to
  yield a pathogen.

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Listeriosis Elderly Immuncompromised
Death
Large Intestine (gastroenteritis)
Brain (meningitis)
Small Intestine
Blood
Liver Spleen
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Listeriosis in the fetus
Abortion
Sepsis at birth
Mother
Granulomatosis infantiseptica
Fetus
Ingestion
Placenta
Small Intestine
Liver Spleen
Blood
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Clinical Case
A 38-year-old woman was at her 31st week of
gestation. Fever and chills for 3 days. No
history of respiratory, urinary or
gastrointestinal tract infection. Chills and
general malaise 3 days prior to this admission.
Decreased fetal movement and fetal tachycardia
were noted. On admission, leukocytosis.
Rupture of membrane with meconium stain 12 h
after admission. 14 hours after admission, the
fetal heart rate suddenly decelerated. Decreased
fetal movement was also noted. A male infant in
fetal distress was delivered by caesarean section
15 h after admission. Infant was transferred to
the neonatal ICU for possible neonatal sepsis.
Seizure developed. Cerebrospinal fluid (CSF) was
yellow and turbid. Treatment of neonatal
meningitis. Blood cultures and CSF culture
yielded the same organism.
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Listeriosis in the Neonate
5 days 3 weeks post delivery Purulent
meningitis OR Meningo-encephalitis with sepsis
lt 5 days post delivery Sepsis Meningitis
Mother
early onset
late onset
Ingestion
Neonate
Small Intestine
Large Intestine
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Pathogenesis

• Internalins
• InlA is responsible for uptake into epithelial
  cells and is required for crossing the intestinal
  barrier
• InlB mediates entry into a variety of cell types
  but does not contribute to crossing of the
  intestinal cell barrier
• Both InlA and InlB are needed for traversal of
  the fetoplacental barrier

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InlA signaling pathway
Listeria
E-cadherin
Plasma Membrane
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InlB signaling pathway
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Pathogenesis

• Phagolysosome - low pH activates exotoxin
• ß-hemolysin (listeriolysin O- exotoxin)
• Cholesterol-dependent cytolysin
• Forms a pore in the phagolysosome
• Only present in virulent strain

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Pathogenesis

• Phospholipase C (2 types)
• Phosphatidylinositol-specific phospholipase C
• Phosphatidylcholine phospholipase C- broad-range
  phospholipase
• Both enzymes act in synergy with listeriolysin O
  to lyse the phagolysosome.

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Cell-cell transmission

• Entry
• Internalins

Bacteria
phagolysosome

• Fusion with another cell

• Escape
• 1. listeriolysin O
• 2. Phosphatidylinositol-specific phospholipase C

Extrusion via filopods
actin tail Movement through cell
replication
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Treatment

• Penicillin or ampicillin alone or in combination
  with gentamicin

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Overview

• Infection is occupationally related
• Fishermen
• Butcher
• Veterinarians
• Contact with animals, their products or wastes
• Three types of human infection
• Localized cutaneous
• Generalized cutaneous
• Septicemic which is associated with
  endocarditis

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Bacteriological identification

• Gram positive
• Microaerophillic bacillus
• Thin, pleomorphic
• Non-motile
• Non-encapsulated
• Non-sporulating

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Morphology/Physiology

• Grows well on most laboratory media.
• After 48 hours colonies are small to pinpoint.
• Colonies are non-pigmented and transparent.
• The a-hemolysis will develop after two days

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Sources of Erysipeloid

• Acquired through skin abrasions
• Inflammatory violaceous lesion at the infection
  site (usually fingers or hand)
• Lesion is pruritic and painful
• Lesion is non-supporative

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Pathogenic Mechanisms

• Hyaluronidase
• Neuraminidase

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Diagnosis and treatment

• Diagnosis
• History
• Culture
• Treatment
• Penicillin
• Resistant to vacomycin

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Bacillus anthracis Overview
CDC
A photomicrograph of Bacillus anthracis bacteria
using Gram stain technique.
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Anthrax Overview

• Gram-positive rods which form spores.
• Transmission by contact with infected animals or
  contaminated animal products.
• Primarily disease of cattle, sheep and goats.
• No person-to-person transmission of inhalation
  anthrax.

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Anthrax Overview

• 3 distinct clinical presentations
• Cutaneous
• Gastrointestinal
• Pulmonary

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Bacterial identification of B. anthracis
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Culture Characteristics

• Incubated at 35-37o C
• Cultures examined within 18-24 hours of
  incubation
• Growth may be observed as early as 8 hours after
  inoculation.
• Grows well on Sheep Blood Agar, but does not grow
  on MacConkey agar.

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Colony Characteristics

• At 15-24 hours well isolated colonies are 2 - 5
  mm.
• Non-hemolytic, non-pigmented.

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Sheep blood agar plate culture of Bacillus
anthracis and Bacillus cereus.
CDC/Dr. James Feeley
In contrast to colonies of B. cereus and B.
thuringiensis, colonies of B. anthracis are not
ß-hemolytic.
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Microscopic Characteristics

• Vegetative cells are in short chains of 2-4 cells
  that are encapsulated.
• Large gram-positive rod
• The capsule can be visualized microscopically
  using India Ink.
• Spores are not generally present in clinical
  material CO2 levels within the body inhibit
  sporulation.
• Spores may be seen in material from wound
  eschars, but would not be seen in body fluids.

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India Ink Staining of Clinical Samples (Blood and
CSF) for Capsule

• India ink for visualization of encapsulated B.
  anthracis in clinical samples.
• The capsule will appear as a well-defined clear
  zone around the cells for the positive control.

CDC/Courtesy of Larry Stauffer, Oregon State
Public Health Laboratory
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Isolation From Clinical Specimens

• Blood specimens
• There may be enough organisms in the blood to see
  them on direct smears by gram stain.
• B. anthracis appears as short chains of 2-4 cells
  which maybe encapsulated.
• Swab specimens for cutaneous Anthrax.
• Sputum specimens
• CSF specimens.

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Pathogenic Mechanisms

• Exotoxins
• plasmid-encoded (pXO1)
• 3 components
• Protective Antigen
• Edema Factor
• Lethal Factor
• Capsule
• Plasmid encoded (pXO2)
• Poly D-glutamic acid

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Exotoxins

• Protective antigen
• Forms a pore in the endosome allowing EF and LF
  to enter the cytosol of the cell.
• Edema Factor
• calmodulin-dependent adenylate cyclase
• Lethal factor
• a zinc-dependent endopeptidase specific for
  mitogen-activated protein kinase kinase (MAPKK)

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Clinical Anthrax

• Cutaneous
• Gastrointestinal
• Inhalational

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Cutaneous

• Most common form (95)
• Inoculation of spores under skin
• Incubation hours to 7 days
• Small, itchy, raised area on the skin ? ulcer
  surrounded by blister like lesions (24-28h)
• Blister ruptures to form a painless ulcer
  (eschar) with a characteristic black necrotic
  center
• Profound edema around lesions
• Death 20 untreated rare if treated

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Cutaneous Anthrax
CDC27 year old white female with cutaneous
anthrax on right forearm
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Gastrointestinal

• Ingestion of contaminated meat
• Incubation hours or up to 7 days
• Fever, acute gastroenteritis, vomiting blood,
  bloody diarrhea
• Mortality rate 25 -60

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Gastrointestinal anthrax
CDC Intestinal lesion of GI anthrax
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Inhalational

• Inhalation of spores
• Most likely form of bioterrorist attack.
• Incubation 1 to 6 days, but can be as long as 43
  days.
• Gram stain of the blood and blood culture, but
  not until late in the course of the illness.
• Only vegetative encapsulated bacilli are present
  during infection, spores are not found in the
  blood.

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Inhalational

• Gradual onset (1-6 days)
• fever, non-productive cough, muscle pain, malaise
  
• Short period of improvement
• Abrupt development of severe respiratory distress
• dyspnea
• diaphoresis
• stridor
• cyanosis
• Shock and death usually occur within 24-36 h
  after the onset of respiratory distress
• Mortality rate 100 despite aggressive treatment

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Anthrax Treatment

• Most B. anthracis strains are sensitive to a
  broad range of antibiotics.
• Penicillin, ciprofloxacin, or doxycycline
• Treatment should be initiated early.
• Start oral antibiotics as soon as possible.
• Antibiotics for 60 days.

Post-Exposure Treatment
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Anthrax Vaccine

• Current U.S. vaccine (FDA Licensed)
• FDA approved for persons 18-65 year of age
• 93 protective against cutaneous and may also be
  protective against inhalation anthrax.
• FDA approved for 6 dose regimen over 18 months
  with yearly boosters
• 3 dose regimen (0, 2, and 4 weeks) may be
  effective for post-exposure treatment

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Anthrax Vaccine

• The vaccine is a cell-free filtrate that contains
  protective antigen and alum.
• Pregnant women should not be vaccinated.
• Limited availability