vibrio

• Vibrio parahaemolyticus


  • Primary cause of so-called summer diarrhea in Japan (acquired during summer in Japan)
  • Halophilic bacterium
  • Causes acute gastroenteritis after ingestion of contaminated seafood such as raw fish or shellfish
  • Incubation period: 12-24 hours
  • Serotype: O3:K6 – implicated in numerous food-borne outbreaks in various parts of the world
  • Halophilic requirement: 1% - 8% NaCl
  • Facultative anaerobe, gram (-) rod
  • Does not grow well on some of the routine differential media used to grow salmonellae and shigellae, but it does grow well on blood agar
  • Grows well on TCSB agar- green colonies does not ferment sucrose
• TCSB


  Thiosulfate Citrate Bile Salt Sucrose Agar; ind: Bromthymol blue
• Green colonies


  Without acid (V. cholerae)
• Vibrio parahaemolyticus


  • Kanagawa phenomenon – a heat-stable hemolysin that is able to lyse human erythrocytes in a special, high-salt mannitol medium (Wagatsuma agar)
  • Usually, the bacteria cannot lyse RBC at high salt concentration but Vibrio parahaemolyticus can lyse RBC even at high salt concentration environment
• Clinical manifestations


  Signs and symptoms occur after 24-48 hrs of ingestion
• Vibrio vulnificus


  • 2nd to V. cholerae in causing septicemia and wound infections
  • Can utilize lactose: common Vibrio spp. cannot utiize lactose, only sucrose (but not all), but V. vulnificus can ferment lactose (LF)
• Treatment of choice (TOC)

  Fluoroquinolones, third-generation cephalosporins (ceftriaxone), and doxycycline
• Vibrio alginolyticus


  • Least pathogenic for humans
  • Strict halophile: least 1% of NaCl
  • Able to tolerate up to 10% NaCl
  • Occupational hazard: people in constant contact with seawater, sch as fishermen or sailors
  • If associated with infection: wound infection, eye infection
• Specimen Collection


  1. Collect to area that are infected

  2. Diarrhea: stool; wound: aspirates

  3. Stool: inoculated within 2-4hrs of collection onto appropriate agar media

  4. For delayed processing: Alkaline Peptone Water (APW) – since stool is non sterile, it may contain a lot of normal flora gram (-) bacilli; we use APW as an enrichment medium because it has characteristics that can support vibrio; high NaCl and High PpH – support the growth of Vibrio spp. but not other gram (-)

  5. Cary-Blair transport medium and refrigerated

  6. Buffered Glycerol Saline – not recommended because glycerol is toxic for Vibrio spp.

  
• Direct Microscopic Examination


  • Use Dark field or phase-contrast microscopy to see motility (e.g tumbling, leaf-like motility)
  • Shooting star motility: Vibrio cholerae O1; gram (-) bacilli
• Culture Media


  • Nutrient Agar
  • Sheep Blood Agar – with 0.5% NaCl
  • MacConkey Agar – non fermenters
  • Thiosulfate Citrate Bile Salt Sucrose (TCSB) agar
  • Alkaline Peptone broth or water – with 1% NaCl and 8.5 pH
  • Taurocholate peptone broth with pH of 8.0 – 9.0
  • CHROMagar Vibrio – V. cholerae, V. parahaemolyticus, and V. vulnificus
• MacConkey Agar


  • Has lactose
  • NLF (colorless), except V. vulnificus (pink)
• TCSB agar


  • Selective: sodium thiosulfate, oxygall (bile salts) – inhibit gram (+) cocci, gram (-) bacilli that are not commonly see on stool
  • Differential: has sucrose
  • Ph: bromthymol blue
  • Yellow – acid
  • Green – without acid
  • High Ph: tolerated by Vibrio spp.
• Sucrose fermenting Vibrio species

  • Vibrio cholerae
  • Vibrio alginolyticus
  • Vibrio fluvialis
  • Vibrio furnissii
  • Vibrio cincinnatiensis
  • Vibrio metschnikovii
  • Some V. vulnificus
• Non-sucrose-fermenting (green) Vibrio species

  • Vibrio mimicus
  • Vibrio parahaemolyticus
  • Photobacterium damsela
  • Most of the V. vulnificus

  
• Not all Vibrio spp. grow on TCSB, especially Grimontia hollisae (Vibrio hollisae)
• Colony Appearance


  • Medium to large, smooth, opaque, iridescent with a greenish hue
  • Vibrio cholerae, Vibrio fluvialis, and Vibrio mimicus can be beta-hemolytic NLF, except: V. vulnificus with may be LF
  • If we suspect for gram (-) bacilli: we use MAC NLF
• Identification Tests


  • Oxidase test
  • Nutrient broth with 6% salt – to differentiate Vibrio cholerae, Vibrio mimicus and Aeromonas spp.
  • String test: to differentiate Vibrio spp. (+). from Aeromonas spp. (-)
  • Vibrio static test: 0/129 (2,4-diamino-6,7-diisopropylpteridine) – to differentiate vibrios (susceptible) from other oxidase positive glucose fermenters (resistant) and to differentiate V. cholerae O1 and non-O1 (susceptible) from other Vibrio spp. (resistant)
  • Oxidase (-): Vibrio metschnikovii
  • Indole (-): Photobacterium damsela
  • Gas from glucose (+): Vibrio furnissii
  • Lactose (+): Vibrio vulnificus
  • Lysine decarboxylase (-): Grimontia hollisae, Vibrio fluvialis, Vibrio furnissii
  • Arginine decarboxylase (+): Photobacterium damsela, Vibrio fluvialis, Vibrio furnissii
  • Ornithine decarboxylase (+): Vibrio cholerae, Vibrio parahaemolyticus, Vibrio mimicus, Vibrio vulnificus
• Non-enteric bacteria


  • Vibrio spp., Aeromonas spp., Pleisiomonas spp.
  • Not normal flora
  • Found in water
  • Oxidase (+)
  • Pleisiomonas spp. are part of Enterobacteriaceae but they are oxidase (-)
• Enterobacteriaceae


  • Enteric
  • Cause GIT infection
  • Oxidase (-)
• Aeromonas


  • Oxidase – positive
  • Glucose fermentation; gram negative rods
  • May resemble morphologically members of the family of Enterobacteriaceae
  • Grows well on blood agar: B-hemolytic (BAP)
• Aeromonas caviae


  Cause gastroenteritis, ranging from watery diarrhea (most common) to dysentery-like illness – presence of blood, mucus & pus in stool
• Aeromonas hydrophila


  Cause of wound infections; traumatic soft tissue injuries, described in patients with hematologic malignancies and/or liver disease – anemia, leukemia
• Treatment of choice (TOC) for Aeromonas

  Third-generation cephalosporins, aztreonam, and carbapenems as well as aminoglycosides
• Intestinal Infections


  • Acute secretory diarrhea often accompanied by vomiting
  • Acute dysenteric form of diarrhea similar to shigellosis, with blood and mucus – dysentery associated by shigella -shigellosis
  • Chronic diarrhea usually lasting more than 10 days
  • Cholera-like disease including rice water stools – V. cholerae
  • Nebulous syndrome common referred to as traveler's diarrhea (similar to enterotoxigenic E. coli) – ICP patients: pediatric, geriatric
• Extraintestinal Infections


  • Septicemia
  • Wound infections
  • Meningitis, osteomyelitis, pelvic abscesses, otitis, cystitis, endocarditis, peritonitis, cholecystitis, keratitis associated with contact lens wear, and endophthalmitis
• Aeromonas caviae


  • Gastrointestinal infections, especially in neonate and pediatric populations
  • Inflammatory bowel disease
• Aeromonas hydrophila


  Wound infections
• Aeromonas veronii


  • Biovars sobria and veronii
  • Hemolytic – uremic syndrome (HUS) or kidney disease that might require kidney transplantation
• Aeromonas veronii biovar sobria


  Linked to cholera-like disease characterized by abdominal pain, fever, and nausea
• Culture Media for Aeromonas

  • Sheep's Blood Agar – strong B-hemolysis
  • McConkey Agar (MAC) – ferments lactose
  • Modified cefsulodin Irgasin-novobiocin (CIN) II plate – has 4𝜇𝜇𝜇𝜇 of cefsulodin
  • CIN Medium - 15𝜇𝜇𝜇𝜇 of cefsulodin
• Modified cefsulodin Irgasin-novobiocin (CIN) II plate

  Has high yield of Aeromonas because of low cefsulodin; also has ampicillin
• CIN Medium


  • No ampicillin
  • Pink – centered colines from the fermentation of mannitol, with an uneven, clear apron resembling Yersinia enterocolitica
• Presumptive Identification Tests for Aeromonas


  • Oxidase test: Aeromonas (+)
  • Spot indole test
  • Ability to grow in the presence of NaCl – not high (4.5%)
  • String test (-)
• Campylobacter


  • Strict anaerobe, microaerophilic environment – reduced amount of O2
  • Curved, comma or S-shaped, gram negative, non-spore forming rods: seagull wings shapes
  • Primarily zoonotic organisms – cause abortion to domestic anima
• Aeromonas


  Bacteria characterized by abdominal pain, fever, and nausea
• Sheep's Blood Agar


  • Strong B-hemolysis
  • Aeromonas hydrophila, Aeromonas veronii biovar sobria and Aeromonas jandaei grow on it
• McConkey Agar (MAC)


  • Aeromonas ferments lactose
• Modified cefsulodin Irgasin-novobiocin (CIN) II plate


  • Has 4μg of cefsulodin
  • Has high yield of Aeromonas because of low cefsulodin
  • Also has ampicillin
• CIN Medium


  • Has 15μg of cefsulodin
  • No ampicillin