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Vibrio, Aeromonas, Plesiomonas, Campylobacter, & Helicobacter
MLAB 2434 – Microbiology Keri Brophy-Martinez
Vibrio species
HabitatAquatic environments; fresh water,
brackish and marine or salt water• Except for V. cholerae and V. mimicus,
all are halophilic (salt-loving)Tolerates alkaline environments
• High pH toxic to other micro-organisms
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 Possess O and H antigens
• Allows serotyping
Vibrio species (cont’d)
Gram stain Curved design
Vibrio species:Other Notable Characteristics
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 desoxycholate
Vibrio species:Clinical Infections
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:Hints to Infection
Best indicators of Vibrio infection is presence of recognized factors Recent consumption of raw seafood
(especially oysters) Recent immigration or foreign travel 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 choleraAlso 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:Clinical Infections
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
• Loss of electrolytes & water Dehydration is usual cause of death Man is the only host
Vibrio cholerae:Identification Methods Routine media
SBA• Medium-large colonies; smooth, opaque,
irredescent with a greenish hue; might see α or β- hemolysis
MAC• NLF
Selective/Differential Media TCBS (Thiosulfate citrate bile salts sucrose) agar
• Yellow colonies indicate acid production• Positive result for V. cholerae
Vibrio parahaemolyticus
“Summer diarrhea” in Japan Gastroenteritis
• Most cases traced to recent consumption of raw, improperly cooked, seafood, especially oysters
• Gastrointestinal symptoms are generally self-limiting; watery diarrhea, moderate cramps or vomiting
Skin infections associated with salt water exposure
Vibrio parahaemolyticus:Laboratory Diagnosis
Halophilic Nonfermenters of lactose Oxidase + Indole + Colonies are green on TCBS agar
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 wound
Vibrio vulnificus: Wound Infections
Vibrio vulnificus:Laboratory Identification
MacConkey agarFerments lactose
TCBS agarNon-sucrose fermenterAppears as clear, blue-green
Oxidase +
Aeromonas
Ubiquitous, motile, curved gram-negative rods widely distributed in fresh and salt water environments
Isolated from produce and meat sources, contaminated food and water
Aeromonas:Infections 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 Resulting from traumatic water-related
wound Septicemia
Targets immunocompromised
Aeromonas:Skin Infections
Aeromonas:Colony morphology
SBA large, round, raised, opaque
colonies, often mucoid, can be translucent- white; Β-hemolytic
MACFerments lactose
CIN (cefulodin, irgasan, novobiocin) pink-centered colony
Aeromonas:Laboratory Diagnosis Β- hemolytic colonies
• Perform oxidase(+) and indole (+)• To distinguish between Vibrio use
O/129• Vibrio= “S”• Aeromonas =“R”
Plesiomonas
Habitat Found in soil and aquatic
environments; particularly fish and estuarine waters of tropical and subtropical climates
Warm and cold blooded animals are carriers
Occupational exposure is the source of some infections;(fish handlers, vets, zookeepers)
Plesiomonas:Infections 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 shrimp
Also causes bacteremia or meningitis in immunocompromised after animal exposure
Plesiomonas:Laboratory Identification
SBA: shiny, opaque, raised center with smooth edge; nonhemolytic
MAC: variable TCBS
No growth Laboratory Diagnosis
Oxidase positiveO/129 “S”
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 species
Curved, gram-negative rods appearing as long spirals, S shapes, or seagull-wing shapes
Stains poorly Microaerophilic and capnophilic
environment for growth Require selective media (CAMPY) Incubation at 42o for 2-3 days Exhibit “darting” motility
Campylobacter species
Colony Morphology CAMPY( Brucella agar + 1% sheep rbcs +
vancomycin, trimethoprim, polymyxin B, amphotericin B, cephalothin)
• Colonies are moist, runny-looking and spreading, nonhemolytic
Will not grow on MAC Laboratory Diagnosis
Darting motility in hanging drop Oxidase positive Catalase positive
Helicobacter pylori
Associated with gastric and duodenal ulcers, gastric malignancy, and gastritis
Transmission Fecal-oral Oral-oral Zoonotic
The organism does not invade the gastric epithelium, but the host immune antibody response causes inflammation
Helicobacter pylori
Tissue BiopsyDetects urease production
14C-labeled urea breath test
Traditional culture generally not used
Helicobacter pylori
References Engelkirk, P. G., & Duben-Engelkirk, J. (2008).
Laboratory Diagnosis of Infectious Diseases: Essentials of Diagnostic Microbiology . Baltimore, MD: Lippincott Williams & Willkins.
http://explow.com/Vibrio_parahaemolyticus http://www.pharmaceutical-technology.com/projects/
sbl_vaccin/sbl_vaccin4.html http://ridingrickshaw.wordpress.com/2011/08/21/cholera-cots-
beware-of-graphic-pictures/ http://safeoysters.org/medical/symptoms.html Kiser, K. M., Payne, W. C., & Taff, T. (2011). Clinical
Laboratory Microbiology: A Practical Approach . Upper Saddle River, NJ: Pearson Education, Inc.
Mahon, C. R., Lehman, D. C., & Manuselis, G. (2011). Textbook of Diagnostic Microbiology (4th ed.). Maryland Heights, MO: Saunders.