Enterics

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Enterics

• Filename Enterics.ppt

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Gram Negative Rods
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Cardiobacterium hominis

• long filaments, pleomorphic / tear drop
• Gentian violet may be retained in ends, sometimes
  in the middle
• Facultatively anaerobic -- CO2 required
• Strong fermentative reactions (no gas)
• oxidase catalase
• No growth on MacConkey, not hemolytic

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C.hominis contd

• Found in nasal flora
• Associated with dental disease
• -enter the blood stream and adhere to damaged
  heart tissue
• causes endocarditis
• -thick polar caps of tufted material

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Comparison of Gm Neg rods

• oxidase catalase indole
  ferment. NO3reduc.
• C.hominis -
  -
• H.aphrophilus ? - -
  
• Actinobacillus ? -
  
• Pasteurella most
  
• Capnocytophaga - - -
  most
• Eikenella - -
  - corrodens

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Actinomyces comitans

• Should be differentiated from Kingella
• Prevented by good oral hygiene
• Prophylaxis before dental manipulations

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Eikenella

• facultative anaerobic gram negative rod
• E.corrodens -- pits agar (less that 50)
• normal flora opportunistic pathogen
• immunocompromised
• slow growing

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Eikenella corrodens

• Source
• Human bites
• fist fights.
• Usually untreated

• Complications
• septic arthritis
• osteomyelitis
• meningitis
• brain abscesses
• pneumonia
• lung abscesses
• endocarditis

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Calymmatobacterium granulomatis

• Pleomorphic rods, rounded ends, singles or in
  clusters.
• Single or bipolar condensation of chromatin.
• Exudate from infected tissues -- use Wrights or
  Giemsa
• stain - characteristic.
• Intracellular organisms in the cytoplasm of large
• mononuclear phagocytes.
• Capsule prominent.

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C. granulomatis

• C. (Donovania) granulomatis
• Disease granuloma inguinale
• Bug resides in the gut flora. Enters genitals
  by
• autoinoculation or sexual intercourse.
• Penetrate skin and induce an inflammatory
  reaction.
• Tissue destroyed
• Antibodies produced. Cell mediated defense
• mechanisms -- important in recovery. This is
• the granulomatous reaction.

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Flavobacterium

• Aerobic gram negative rod
• most important
• Flavobacterium meningosepticum
• found in water, soil, moist reservoirs in the
  hospital
• Not normal flora of humans
• -opportunists
• Diseases
• 1/ meningitis
• 2/ septicemia
• Resistant to many antibiotics.
• Most have a yellow pigment.
• Grow on ordinary medium.

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S. moniliformis

• Streptobacillus moniliformis
• Causes rat bite fever.
• Found in rats worldwide.
• Transmission rat bite, consumption of
  contaminated
• liquid or food.
• Acute onset high fever, chills, headache,
  myalgias,
• arthritis. Can reoccur.
• 10 mortality if untreated -- penicillin.
• Culture serology
• Kits available -- antisera and specific antigen
• Spirillum minor - spiral shaped, cant be
  cultured
• Found worldwide, primarily Asia

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Enterics
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Enterobacteriaceae

• Edwardsiella
• Ewingella
• Hafnia
• Serratia
• Salmonella
• Shigella
• Yersinia

• Escherichia
• Enterobacter
• Klebsiella
• Citrobacter
• Kluyvera
• Proteus
• Providencia
• Morganella

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Enterobacteriaceae

• Virulence Factors
• cell wall is an important virulence factor
• Endotoxin or lipopolysaccharide composed of
• O polysaccharide
• polysaccharide core
• lipid A - which form repeating structural units

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Endotoxin

• fever
• leucopenia leucocytosis
• activation of complement
• thrombocytopenia
• can lead to shock and death

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Endotoxins Pyrogenic Effects

• Pyrogenic - fever producing
• present in virtually every biologic assay system
  ever examined
• organism present in water systems
• Heat stabile

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Enteric Antigenic Phase Variation

• Antigens K-capsular H-flagellar
• Exhibit phase variation expressed under
  certain conditions.

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Enterotoxins

• Heat stabile
• E.coli,
• Yersinia
• Enterocolitica
• Citrobacter freundii

• Heat labile
• Shiga Type
• Cholera Type

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Shiga Type Enterotoxins

• Verotoxin
• E. coli
• Shigatoxin
• Shigella

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Cholera Type Enterotoxins

• cholerae type
• V.cholerae is not in Enterobacteriaceae
• E. coli, Salmonella, Klebsiella
• A B Toxins

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Community acquired infections

• E. coli is major cause of urinary tract
  infections
• also Proteus, Klebsiella, Enterobacter sp.
• Proteus mirabilis is the major cause of infection
  related kidney stones
• Klebsiella pneumoniae severe pneumonia

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Nosocomial Infections

• 45 of nosocomial Infections in the USA are
  caused by the Enterobacteriaceae
• Escherichia, Klebsiella, Enterobacter, Serratia,
  Citrobacter Proteus, Providencia
• Gram negative rods all found in the indigenous
  flora most frequently in the intestine

E. coli is numero uno
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Nosocomial InfectionsSites of primary infection

• urinary tract
• lower respiratory tract
• surgical wounds
• blood stream
• skin

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Endotoxins Structure

• Toxic liposaccharide of outer membrane of Gram
  negative bacteria. Released on destruction of the
  cell
• O side chains --- Core --- Lipid A
• oligosaccharides polysaccharide

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Escherichia coli
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E. coli Diseases

• Gastorenteritis
• Septicemia
• Urinary Tract Infection
• Neonatal menigitis

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E. coli Septicemia

• Intestinal perforation and disseminated urinary
  tract infections are the major cause of
  septicemia.

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E. coli Urinary Tract Infection

• serotypes O4, O6, O75

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E. coli Virulence

• resist killing in serum
• produce hemolysins
• adhere to epithelial cells

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E. coli Antigens

• Antigens O, H, and K.
• certain serotypes are associated with specific
  diseases

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Adhesion

• Most Enterobacteriaceae have Fimbriae
• P fimbriae E. coli - agglutinate human RBC with
  P group antigen
• uropathogenic E. coli
• S fimbriae bind to sialyl galactosides on human
  erythrocytes
• E. coli that cause neonatal sepsis and meningitis

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Exotoxins

• Proteins, most potent by unit weight, heat-labile
  generally.
• Gram positive and Gram negative organisms
• Specific immune effects - antitoxins
• Specific cellular effects

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E coli Neonatal meningitis

• rare in North America
• acquired in birth canal
• virulence associated with K antigen (capsular)

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E.coli Gastroenteritis

• Small Intestine
• enterotoxigenic
• enteropathogenic
• enteroaggregative
• Large Intestine
• enteroinvasive
• enterohemorrhagic

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E coli Small intestine

• Enterotoxigenic
• Travelers Diarrhea
• Infant Diarrhea
• Enteropathogenic
• Infant non-bloody stools
• Enteroaggregative
• Infant persistant and may have blood in stool

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E.coli Large Intestine

• Enteroinvasive
• watery, then dysentery-like
• Enterohemorrhagic
• hemorrhagic colitis

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Escherichia coli

• common in large numbers in intestine of mammals
  and many other warm blooded animals

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E.coli Epidemiology

• North America Western Europe
• most commonly associated with endogenous
  infections (urinary tract infections most
  frequent)
• Gastroenteritis not as common as endogenous
  diseases

• Countries with poor hygiene
• bacterial sepsis
• neonatal meningitis
• gastroenteritis

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E. Coli Pathogenicity

• Enteropathogenic
• Enterohemorrhagic

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Enteropathogenic E.coli

• Adhere to cells of small intestine. Also called
  enteroadherent. One of the adherence factors is
  plasmid mediated.

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Enterohemorrhagic E coli

• hemorrhagic Gastroenteritis
• hemolytic Uuremic Syndrome

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Hemorrhagic gastroenteritis

• Shiga-like toxin half of the E. coli that cause
  the diseases are serotype 0157H7.
• Hemorrhagic gastroenteritis mild to severe,
  mostly in children lt 5, undercooked ground beef
  and unpasteurized milk.

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Hemolytic uremic syndrome

• acute renal failure, thrombocytopenia,
  microangiopathic (small blood vessels), hemolytic
  anemia. Drop in blood cells due to hemolysis of
  red cells in small blood vessels.

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The End
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Short Answers

• Construct a table of the virulence factors
  associated with ??? and the biological activity
  of each
• Use a series of no more than four diagrams to
  describe the mechanism of ??? activity
• Describe the clinical manifestions ???
• Construct a table listing the common ??? species
  and the associated human diseases.