Enterics

Filename: Enterics.ppt

Gram Negative Rods

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

C.hominis cont’d:

• 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

Comparison of Gm Neg rods

• oxidase catalase indole ferment. NO3reduc.

• C.hominis + - + + -

• H.aphrophilus ? - - + +

• Actinobacillus ? + - + +

• Pasteurella + + most + + +

• Capnocytophaga - - - + most +

• Eikenella + - - - + corrodens

Actinomyces comitans

• Should be differentiated from Kingella

• Prevented by good oral hygiene

• Prophylaxis before dental manipulations

Eikenella

• facultative anaerobic gram negative rod

• E.corrodens -- pits agar (less that 50%)

• normal flora: opportunistic pathogen

• immunocompromised

• slow growing

Eikenella corrodens

• Source
  • Human bites
  • fist fights.

• Usually untreated

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

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.

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.

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.

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, can’t be cultured

• Found worldwide, primarily Asia

Enterics

Enterobacteriaceae

• Edwardsiella

• Ewingella

• Hafnia

• Serratia

• Salmonella

• Shigella

• Yersinia

• Escherichia

• Enterobacter

• Klebsiella

• Citrobacter

• Kluyvera

• Proteus

• Providencia

• Morganella

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

Endotoxin

• fever

• leucopenia: leucocytosis

• activation of complement

• thrombocytopenia

• can lead to shock and death

Endotoxins: Pyrogenic Effects

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

Enteric Antigenic Phase Variation:

• Antigens: K-capsular & H-flagellar

• Exhibit phase variation expressed under certain conditions.

Enterotoxins

Heat stabile

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

Heat labile

• Shiga Type

• Cholera Type

Shiga Type Enterotoxins

• Verotoxin
  E. coli
  

• Shigatoxin
  Shigella
  

Cholera Type Enterotoxins

• cholerae type
  • V.cholerae is not in Enterobacteriaceae

• E. coli, Salmonella, Klebsiella

• A & B Toxins

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

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

Nosocomial InfectionsSites of primary infection

• urinary tract

• lower respiratory tract

• surgical wounds

• blood stream

• skin

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

Escherichia coli

E. coli: Diseases

• Gastorenteritis

• Septicemia

• Urinary Tract Infection

• Neonatal menigitis

E. coli: Septicemia

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

E. coli: Urinary Tract Infection

• serotypes O4, O6, O75

E. coli: Virulence

• resist killing in serum

• produce hemolysins

• adhere to epithelial cells

E. coli: Antigens

• Antigens O, H, and K.

• certain serotypes are associated with specific diseases

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

Exotoxins

• Proteins, most potent by unit weight, heat-labile generally.

• Gram positive and Gram negative organisms

• Specific immune effects - antitoxins

• Specific cellular effects

E coli: Neonatal meningitis

• rare in North America

• acquired in birth canal

• virulence associated with K antigen (capsular)

E.coli: Gastroenteritis

• Small Intestine
  • enterotoxigenic
  • enteropathogenic
  • enteroaggregative

• Large Intestine
  • enteroinvasive
  • enterohemorrhagic

E coli: Small intestine

• Enterotoxigenic
  • Traveler’s Diarrhea
  • Infant Diarrhea

• Enteropathogenic
  • Infant: non-bloody stools

• Enteroaggregative
  • Infant: persistant and may have blood in stool

E.coli: Large Intestine

• Enteroinvasive
  • watery, then dysentery-like

• Enterohemorrhagic
  • hemorrhagic colitis

Escherichia coli

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

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

E. Coli: Pathogenicity

• Enteropathogenic

• Enterohemorrhagic

Enteropathogenic E.coli

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

Enterohemorrhagic E coli

• hemorrhagic Gastroenteritis

• hemolytic Uuremic Syndrome

Hemorrhagic gastroenteritis

• Shiga-like toxin : half of the E. coli that cause the diseases are serotype 0157:H7.

• Hemorrhagic gastroenteritis: mild to severe, mostly in children < 5, undercooked ground beef and unpasteurized milk.

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.

The End

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.