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.