Vibrio species

• Vibrio is a

  • Asporongenous
  • Gram (-) rods
  • 0.5 - 0.8 Mm in diameter by 1.4 - 2.6 Mm
  • Facultative anaerobic
  • Shape: Curve or comma rods
  • Positive in: Motile, Catalase and Oxidase
• Vibrio is

  • able to produce nitrate to nitrate except for: V. metschnikovii
  • found in marine and surface waters
  • growing within broad temp range (14 - 40 C)
  • halophilic except: V. cholerae and V. mimicus
  • Positive in string test - mucoid "stringing" rxn
  • susceptible to vibriostatic compound O/129
• Vibrio cholerae

  • cause of cholera
  • rice water stool
  • diarrheal fluid loss: more than 1 L/h
  • Cholera toxin or choleragen, a powerful enterotoxin virulence factor is heat labile
  • Once ingested, the bacteria will colonize our small intestine where they'll multiply and produces choleragen
  • Grows in brackish and marine waters
  • Not part of our normal flora
  • Motile polar flagellum
• The basis of our classification or categorization of Vibrio

  cholerae is the presence or differences of the O antigen
• ANTIGENIC STRUCTURE AND BIOLOGICAL CLASSIFICATION of Vibrio

  • O lipopolysaccharides - O1 and O139 cause epidemic and pandemic cholera

  A.) V. cholerae O1

  • Ogawa (A,B)
  • Inaba (A,C)
  • Hikojima (A,B,C)

  B.) V. cholerae O139

  C.) V. cholerae non-O1 – resemble V. cholerae but fail to agglutinate [does not agree] in O1 antisera
• ANTIGENIC STRUCTURE AND BIOLOGICAL CLASSIFICATION of Vibrio

  • Two biotypes of epidemic V. cholerae

  (1) CLASSIC - does not produce hemolysis [chicken RBC], negative in VPT, and susceptible in polymyxin B

  (2) EL TOR - produces hemolysin, positive in Vouges-Proskauer Test (VPT) and is resistant in polymyxin B
• VIRULENCE FACTORS of Vibrio

  • Cholera toxin (CT)
  • Zonula occludens (Zot) toxin (enterotoxin)
  • Accessory cholera enterotoxin (Ace) toxin
  • O1 and O139 somatic antigens
  • hemolysin/cytotoxins
  • Motility and chemotaxis
  • Mucinase production
  • toxin coregulated pili (TCP)
• Vibrio parahaemolyticus

  • Primary cause of so-called summer diarrhea in Japan
  • Haemophilic bacterium
  • Causes acute gastroenteritis after ingestion of contaminated seafood like raw fish or shellfish
  • Incubation period - 12-24 hours
  • Halophilic requirement - 1 to 8% NaCl
  • Facultative anaerobe
  • does not grow on BAP
  • Grow well in TCBS [Thiosulfate Citrate Bilesalt Sucrose]
  • pH indicator: Bromthymol blue
  • Acid: Yellow colonies
• V. parahaemolyticus

  > serotype O3:K6 which is implicated in numerous food-borne outbreaks in various parts of the world.
• Vibrio haemolyticus : Clinical Manifestations

  • Gastrointestinal disease - self-limited [gumagaling ang patient without any other medication; manifest signs and symptoms 24-48 hrs. after ingestion of contaminated seafood]
  • Kanagawa phenomenon - heat stable hemolysin produced by V. haemolyticus that is able to lyse human erythrocytes [RBC] in a special, high salt mannitol medium (wagatsuma agar)
• Vibrio vulnificus

  • can utilize/ferment lactose
  • most vibrios only ferment sucrose
  • Vibrio doesn’t only cause gastrointestinal infection, it can also cause septicemia and wound infections.
  • Secondary to Vibrio cholerae, this is the second most common organism that causes septicemia.
• Vibrio vulnificus

  Infections include:

  - primary septicema

  - wound infections (aquatic wound that often present as cellulitis)

  TOC

  • fluroquinolones
  • third-generation cephalosporins
  • doxycycline
• Vibrio alginolyticus

  • if associated with infections, they are associated in wound infections and eye infections
  • Least pathogenic for humans
  • Strict halophile: requiring at least 1% NaCl
  • able to tolerate up to 10% NaCl.
  • Occupational hazard: people in constant contact with seawater, such as fishermen or sailors
• LABORATORY DIAGNOSIS: SPECIMEN COLLECTION

  • Stool: inoculated within 2-4 hours of collection onto appropriate agar media [ASAP]
  • For delayed processing: mixed in a Cary-Blair transport medium and refrigerated
  • If suspecting the presence of vibrio in stool, we will be using APW [Alkaline Peptone Water].
  • Buffered glycerol saline – not recommended as a transport or holding medium since Glycerol is toxic for vibrios
• LABORATORY DIAGNOSIS : DIRECT MICROSCOPIC EXAMINATION

  • Gram negative bacilli
  • Dark-field or phase-contrast microscopy
  • “shooting star” motility: V. cholerae O1
• LABORATORY DIAGNOSIS : CULTURE

  • Nutrient Agar or SBA (0.5% NaCl)
  • MacConkey Agar – non-fermenters
  • Thiosulfate Citrate Bile Salt Sucrose (TCBS) agar
  • Alkaline peptone broth or water, containing 1% NaCl with a pH of 8.5
  • Taurocholate peptone broth (pH, 8.0-9.0)
  • CHROMagar Vibro – V. cholerae, V. parahemolyticus, and V. vulnificus
• SUCROSE-FERMENTING (YELLOW COLONIES) SPECIES

  • V. cholerae

  • V. alinolyticus

  • V. fluvialis

  • V. furnissil

  • V. cincinnatiensis

  • V. metschnikovii

  • Some V. vulnificus
• NONSUCROSE- FERMENTING (GREEN) SPECIES

  • V. mimicus

  • V. parahaemolyticus

  • P. damsela

  (Photobacterium)

  • Most V. vulnificus strains

  - Not all Vibrio spp. grow on TCBS, especially Grimontia hollisae

  (formerly Vibrio)
• COLONY APPEARANCE

  • Medium to large, smooth, opaque, iridescent with a greenish hue
• IDENTIFICATION

  • Oxidase test
  • Nutrient broth with 6% salt to differentiate V. cholerae, mimicus and aeromonas spp.
  • String test - to differentiate Vibrio spp. from Aeromonas
  • Vibrio statis test - 0/129