Chapter 16 Enterobacteriaceae Chapter 21 –

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Chapter 16 Enterobacteriaceae Chapter 21 – Powered By Docstoc
					Chapter 21 – Vibrio,
Aeromonas, Plesiomonas, &

MLAB 2434 – Clinical Microbiology
Keri Brophy-Martinez
Chapter 21 – Vibrio species

   Habitat
       Aquatic environments; fresh water,
        brackish and marine or salt water
Chapter 21 – Vibrio species

   General characteristics
       Gram negative rods with polar, sheathed
        flagella in broth but peritrichous,
        unsheathed flagella on solid media
       Rods are “curved” in clinical specimens,
        but small, straight rods after culture
       Facultatively anaerobic
       Asporogenous ( no reproduction by spores)
Vibrio species (cont’d)

   Gram stain of V. cholerae showing
    slightly curved rods
    Vibrio species (cont’d)
   Most are oxidase positive and able to
    reduce nitrates to nitrites
   All are susceptible to vibriostatic
    compound O/129
   Ferments glucose
   Most exhibit a mucoid “stringing” reaction
    when colonies mixed with sodium
   Except for V. cholerae and V. mimicus, all
    are halophilic (salt-loving)
   Some strains can be serotyped
     Vibrio species (cont’d)

 Vibrio species can be isolated from
  a variety of clinical specimens,
  including feces, wound, and blood
 Major species are V. cholerae, V.
  parahaemolyticus, V. vulnificus, and
    V. alginolyticus
        Vibrio species (cont’d)
   Best indicators of Vibrio infection is
    presence of recognized factors
       Recent consumption of raw seafood
        (especially oysters)
       Recent immigration or foreign travel
       Gastroenteritis with cholera-like or rice-
        water stools
       Accidental trauma during contact with
        fresh or marine water
   Medical History important to consider
Vibrio species (cont’d)
          Vibrio cholerae

   V. cholerae O1 is causative agent of
     Also known as Asiatic cholera or
      epidemic cholera; particularly
      prevalent in India and Bangladesh
     Also seen along the Gulf coast of
      the U.S.
     Vibrio cholerae (cont’d)

   Clinical Infection
       Acute diarrheal disease
       Spread through contaminated water, but
        also improperly preserved foods, including
        fish and seafood, milk, ice cream, and
        unpreserved meat
       “Rice Water” stools
         • Caused by cholera toxin or choleragen
         • Dehydration is usual cause of death
         • Man is the only host
Vibrio cholerae (cont’d)

   Colony morphology
       SBA/CA
        • Medium-large colonies; smooth, opaque,
          irredescent with a greenish hue; might
          see α or β- hemolysis
       MAC
        • NLF
Vibrio cholerae (cont’d)

   V. cholerae on TCBS (thiosulfate
    citrate bile salts sucrose) agar
    Colonies are yellow
   TCBS is specific for V. cholerae and
Vibrio parahaemolyticus

 Second most common Vibrio species
  involved in gastroenteritis
 “Summer diarrhea” in Japan

 Most cases traced to recent
  consumption of raw, improperly
  cooked, or recontaminated seafood,
  especially oysters
Vibrio parahaemolyticus
   Gastrointestinal symptoms are
    generally self-limiting; watery
    diarrhea, moderate cramps or
Vibrio parahaemolyticus

   Laboratory Diagnosis
     Colonies are green on TCBS agar
     Halophilic
     Nonfermenters of lactose
     Oxidase +
     Indole +
Vibrio vulnificus
    Found in marine environments along all
     coasts in the U.S.
    Two categories of infections
      • Primary septicemia following consumption of
        contaminated shellfish, especially raw oysters;
        patients with liver dysfunction that results in
        increased levels of iron are predisposed
      • Wound infections following traumatic aquatic
Vibrio vulnificus

   Wound infections with V. vulnificus
Vibrio vulnificus

   Minor wound infection with V.
Vibrio vulnificus

   Laboratory Diagnosis
     Isolate on TCBS agar
     Oxidase +

   Treatment
       Tetracycline
Chapter 21 - Aeromonas

 Ubiquitous oxidase-positive,
  glucose-fermenting, motile, curved
  gram-negative rods widely
  distributed in fresh and salt water
 Isolated from produce and meat
 Seasonal pattern of isolation; May-
Aeromonas (cont’d)

   Aeromonas gastroenteritis usually results
    from consumption of contaminated
    seafood, especially raw oysters or clams;
    illness usually self-limiting, except in very
    young and old populations
   Wound infections usually from A.
    hydrophilia resulting from traumatic
    water-related wound
   Septicemia; targets immunocompromised
Aeromonas (cont’d)

   Aeromonas hydrophilia wound
    infections, after exposure to
    contaminated salt water
Aeromonas (cont’d)

   Colony morphology
     SBA; large, round, raised, opaque
      colonies, often mucoid, can be
      translucent- white; Β-hemolytic
     MAC; LP
     CIN (cefulodin, irgasan, novobiocin);
Aeromonas (cont’d)

   Laboratory Diagnosis
       Β- hemolytic colonies
         • Perform oxidase(+) and indole (+)
         • To distinguish between Vibrio use O/129
            • Vibrio= “S”
            • Aeromonas =“R”

   Treatment
       Trimethoprim sufamethoxazole,
        aminoglycosides, quinolones
Chapter 21 - Plesiomonas

   Habitat
       Found in soil and aquatic environments;
        particularly fish and estuarine waters of
        tropical and subtropical climates
   Warm and cold blooded animals are
   Occupational exposure is the source of
    some infections;(fish handlers, vets,
Chapter 21 - Plesiomonas
   Single species is P. shigelloides
   Oxidase positive, glucose fermenting,
    facultatively anaerobic gram negative
    motile rods

   Primarily causes gastroenteritis resulting
    from consumption of uncooked oysters or
   Also causes bacteremia or meningitis in
    immunocompromised after animal
Chapter 21 - Plesiomonas

   Colony Morphology
     SBA: shiny, opaque, raised center
      with smooth edge; nonhemolytic
     MAC: LP

   Laboratory Diagnosis
     Oxidase positive
     O/129 “S”
Chapter 21 - Plesiomonas

   Treatment
     Self-limited
     If antibiotics needed: quinolones,
      cephalosporins, carbapenems
Chapter 21 – Campylobacter
and Campylobacter-like
   Campylobacter
       Curved, gram-negative rods appearing as
        long spirals, S shapes, or seagull-wing
        shapes; stains poorly, so safranin
        counterstaining should be extended to 2 to
        3 minutes
       Exhibit “darting” motility
       Require selective media (CAMPY)
       Microaerophilic and capnophilic
        environment for growth
       Incubation at 42o
Campylobacter species
   Most common cause of bacterial
    gastroenteritis worldwide is
    Campylobacter jejuni
   Campylobacter infections attributed to
    direct contact with animals and indirectly
    through consumption of contaminated
    water and dairy products and improperly
    cooked poultry
   Campylobacter may also be transmitted
Campylobacter species
   Colony Morphology
      CAMPY( Brucella agar + 1% sheep rbcs +
       vancomycin, trimethoprim, polymyxin B,
       amphotericin B, cephalothin)
        • Colonies are moist, runny-looking and spreading,
      Will not grow on MAC
   Laboratory Diagnosis
      Darting motility in hanging drop, oxidase positive,
       and catalase positive
Campylobacter species
   C. fetus on Campy plate; C. jejuni
    shown on gram stain
Chapter 21 - Helicobacter
   Strongly associated with gastric and duodenal
    ulcers; low grade inflammatory process
   The organism does not invade the gastric
    epithelium, but the host immune antibody response
    causes inflammation
   Can be cultured, but it is so strongly urease positive
    that presumptive identification often made from
    biopsy specimen by testing for urease production
   14C-labeled urea breath test
Chapter 21- Helicobacter
pylori (cont’d)