Vibrio

• In which environments are Vibrio species typically found?

  Aquatic environments including fresh water, brackish or estuarine water, and marine or salt water
• What temperature sensitivity do Vibrio species exhibit?

  They are temperature sensitive and thrive at temperatures greater than 20° C
• From which sources can Vibrio be easily isolated?

  Water, suspended particulate matter, algae, plankton, fish, and shellfish
• Why are Vibrio species less commonly found in winter?

  They can only be found in sediments during winter
• What are the reasons for the increase in clinical isolation cases of Vibrio species?

  • Increase in ocean water temperature due to climate change
  • Increased travel to coastal or cholera-endemic areas
  • Increased consumption of seafood, especially raw or undercooked
  • Increased use of recreational water facilities
  • Larger populations of immunocompromised individuals
  • Increased awareness in clinical microbiology laboratories
• What are some clinical manifestations of Vibrio infections?

  Mild gastroenteritis, cholera, simple wound infections, fatal septicemia, and necrotizing fasciitis
• What factors indicate a possible Vibrio infection?

  • Recent consumption of raw seafood, especially oysters
  • Recent immigration or foreign travel
  • Gastroenteritis with cholera-like or rice-water stools
  • Accidental trauma from contact with fresh, estuarine, or marine water
• Which Vibrio species are commonly isolated in clinical laboratories?

  1. cholerae (serogroups O1 and non-O1), V. parahaemolyticus, V. vulnificus, and V. alginolyticus
• What is the microscopic morphology of Vibrio species?

  They are asporogenous, gram-negative rods, with polar and peritrichous flagella
• How do Vibrio species appear under different growth conditions?

  They appear curved in initial gram stain and small, straight, and highly pleomorphic under suboptimal growth conditions
• What is the oxygen requirement for Vibrio species?

  They are facultatively anaerobic
• Which Vibrio species is not catalase- and oxidase-positive?

  1. metschnikovii
• What is the significance of the vibriostatic compound O/129?

  Most species are generally susceptible to it, exhibiting a zone of inhibition
• What is the string test used for in Vibrio identification?

  It is a positive test indicating mucoid stringing reaction
• Which Vibrio species are halophilic?

  All except V. cholerae and V. mimicus
• What are the major subgroups of V. cholerae based on antigenic structure?

  • V. cholerae O1
  • V. cholerae O139
  • V. cholerae non-O1
• What is the causative agent of cholera?

  Vibrio cholerae
• Where is Vibrio cholerae prevalent?

  In the Bengal region of India and Bangladesh
• How is cholera primarily spread?

  Through contaminated water
• What are the characteristics of cholera stools?

  They are watery and contain numerous flecks of mucus, often described as rice-water stools
• What can cholera lead to if untreated?

  Rapid fluid and electrolyte loss, dehydration, hypovolemic shock, metabolic acidosis, and death
• What is the mild form of gastroenteritis caused by V. cholerae non-O1?

  It lacks the cholera toxic gene
• What is the Kanagawa phenomenon associated with V. parahaemolyticus?

  It is the production of a heat-stable hemolysin that lyses human erythrocytes
• What is the primary cause of primary septicemia in Vibrio vulnificus infections?

  Consumption of shellfish, especially raw oysters
• What is the mortality rate associated with primary septicemia from Vibrio vulnificus?

  40% to 60%
• What is the laboratory diagnosis procedure for Vibrio species regarding specimen collection?

  Body fluids, pus, or tissues should be submitted, and stool specimens should be collected immediately
• What culture media are recommended for isolating Vibrio species?

  • Salt concentration (0.5%), nutrient agar or sheep blood agar (SBA)
  • Thiosulfate citrate bile salt sucrose (TCBS) agar
  • Alkaline peptone water with 1% NaCl (pH 8.5)
• What is the significance of TCBS agar in Vibrio culture?

  It differentiates sucrose-fermenting species from nonsucrose-fermenting species
• What is the purpose of the oxidase activity test in Vibrio identification?

  To determine the oxidase activity of any suspicious Vibrio-like colony
• What is the role of serology in the definitive identification of Vibrio species?

  It is used to screen presumptive V. cholerae isolates with commercially available polyvalent O1 antiserum
• What is the significance of antimicrobial susceptibility testing for Vibrio species?

  It helps determine the appropriate treatment options
• What type of agar is used for antimicrobial susceptibility testing of Vibrio species?

  Mueller-Hinton agar and broth
• What test distinguishes Vibrio from Aeromonas?

  G test
• What is the significance of inositol fermentation in differentiating Vibrio from Plesiomonas?

  Inability to ferment inositol separates Vibrio from Plesiomonas
• How does a positive oxidase reaction help in identifying Vibrio?


  It separates Vibrio from the Enterobacteriaceae, excluding Plesiomonas shigelloides
• What role does carbohydrate fermentation metabolism play in identifying Vibrio?

  It separates Vibrio from the Pseudomonas
• What is often necessary for the identification of halophilic vibrios in biochemical media?

  Adding at least 1% NaCl
• What are the limitations of Rapid and Semiautomated Identification Systems for Vibrio?

  • Generally inadequate for accurate identification
  • Should be confirmed at a reference laboratory
• What is the purpose of serology in identifying Vibrio cholerae?

  To screen presumptive V. cholerae isolates with polyvalent O1 antiserum
• What should be done with presumptive V. cholerae isolates after serology testing?

  They should be forwarded to the health department or a reference laboratory for serotyping