Exam #2 - Vibrio, Aeromonas, Plesiomonas, Campylobacter, Helicobacter

General characteristics of Facultative Gram-Negative Rods

• Ferment glucose

• Oxidase positive

• Grow on Blood Agar and MacConkey Agar

• When motile – polar flagella

Vibrio Organisms

V. cholerae

V. alginolyticus

V. parahemolyticus

V. vulnificus

Vibrio General

• Almost all are pathogenic to humans

• Commonly found in aquatic environments

• Clinical infections:  Gastroenteritis, Wound infections, Septicemia

• All (except V. cholerae) are halophilic = require addition of salt to grow

Vibrio abbreviated morphology and biochemical

• Motile

• Oxidase positive

• Nitrate positive

• Curved GNB

Vibrio

String Test

• Most species exhibit a positive “string test.”  after being emulsified in 0.5% sodium deoxycholate

• Helps distinguish Vibrio from Aeromonas and P. shigelloides

Vibrio – Culture Media

• Grows on BA and usual differential media for stool cultures

• May be hemolytic on BA

• NLF on MAC (except V. vulnificus)TCBS Agar

TCBS Agar

• Thiosulfate Citrate Bile salts Sucrose

• Selective media…gram pos and LF GNB inhibited

• Some Vibrio grow poorly on this media

• Those that grow:  Yellow or Green colonies

Vibrio media TCBS

Results

• V. cholerae and V. alginolyticus will be yellow (ferments sucrose

• V. parahemolyticus and V. vulnificus will produce green colonies (do not ferment sucrose)

Vibrio cholerae

Morphology and characteristics

• BAP – may be beta hemolytic

• MAC – NLF

• TCBS – yellow (sucrose fermenter)

• Identification

  • Sucrose fermenter

  • 0% NaCL = Growth

  • 6% NaCL = Variable growth

Vibrio cholerae – Disease

Cholera

• Rice water stools (10-30/day w/ mucous)

• Enterotoxin production – ‘cholera toxin’

  • Affects absorptive ability of GI tract

• Can lead to death if untreated

• Spread mainly from water, food contaminated with organism

• 7 major cholera pandemics since 1817

• Two major biotypes:  O1 classic and El Tor

Cholera Treatments

• Fluids …. A Lot of FLUID!

• Electrolytes

• Maybe antibiotics

Vibrio parahemolyticus

Morphology and characteristics

Morphology and characteristics

• BAP – May be beta hemolytic (not all)

• MAC – NLF

• TCBS – Green (sucrose -)

• Halophilic – requires at least 1% NaCl for growth….tolerates up to 8% NaCL

Vibrio parahaemolyticus

Identification

• Sucrose non-fermenter

• ODC and LDC = Positive

• 0% NaCL = no growth

• 6% NaCl = growth

Vibrio parahaemolyticus Disease states

Gastrointestinal disease – self limiting

• Raw or improperly cooked seafood

Wound infections

• Open wound exposed to contaminated water or seafood

Vibrio vulnificus

Morphology and Characteristics

• BAP = Non hemolytic

• MAC = LF (usually)

• Isolate on TCBS – colony color is usually green

Vibrio vulnificus

Identification

• Lactose = Fermenter (usually)

• Sucrose = variable (usually non-fermenter)

• ODC = variable

• LDC = positive

• 0% NaCL = no growth

• 6% NaCL = Growth

Vibrio vulnificus

Disease States

Disease States

• Highly invasive and virulent

• Intestinal….raw oysters

  • Invades intestinal mucosa and reaches blood stream

Wound infections

• Most often have a history of a traumatic aquatic wound

• Aggressive tissue infection

Vibrio alginolyticus

Morphology & Characteristics

Morphology and characteristics

• BAP – nonhemolytic

• MAC – NLF

• TCBS – yellow colony

Vibrio alginolyticus

Id

• Sucrose = Fermenter

• LDC = Positive

• ODC = Positive

• 0% NaCL = No growth

• 6.5% NaCL = Growth

Vibrio alginolyticus

Disease States

• Least pathogenic species

• Occupational exposures – fishing, sailing, etc.

• Wound, ear, eye, burn

Aeromonas hydrophila

Morphology & Characteristics

Morphology and characteristics

• Beta-hemolysis on BA

• MAC = NLF or LF

• Large, round, raised opaque colonies, smooth mucoid surface

• CIN agar = growth of pink colonies

Aeromonas hydrophila

Biochemicals

• Gram stain = Straight gram negative rod

• Identification

  • Lactose = variable

  • Sucrose Fermenter

  • Inositol = non-fermenter

  • LDC and ADH = Positive

  • ODC = Negative

  • Indole = Positive

  • Dnase = Positive

  • 0% NaCL = Growth

  • 6% NaCL = No Growth

Aeromonas hydrophila

• Disease States

  • Gastroenteritis

  • Wound infections

  • Septicemia…hepatic, biliary, pancreatic malignancy

  • UTI

  • Osteomyelitis

FOUND IN WATER AND SEWAGE

Plesiomonas shigelloides

Morphology & Characteristics

Morphology and Characteristics

• BAP = Non-hemolytic

• MAC = Both LF and NLF

• Gram Stain = pleomorphic gram-negative rod

• NOTE:  Considered a member of the Family Enterobacteriaceae even though Oxidase positive

Plesiomonas shigelloides

Identification

Identification

• Lactose = variable, delayed fermenter

• Sucrose= non-fermenter

• Inositol = Fermenter

• LDC, ADH, and ODC = Positive

• Indole = Positive

• Dnase = Negative

• 0% NaCL = Growth

• 6% NaCL = No Growth

Plesiomonas shigelloides

Habitat & Disease States

Habitat

• Fresh or brakish water in tropical areas

Disease States

• Gastroenteritis

  • Ingestion of contaminated water or food

  • Shares antigenic structures with Shigella but less virulent

Microaerophilic GNB

Species and Id

Species

Campylobacter

Helicobacter

• Gram Negative Rods

• Oxidase Positive

• Glucose = Asaccharolytic

• Microaerophilic

• Curved Bacilli

Campylobacter species

Infections

Infections

• Found in intestinal tract of animals (poultry, cattle, etc.)

• Associated with diarrhea and systemic infections

• Humans infected when consuming contaminated food, milk, water

• Has been associated with Guillain-Barre syndrome

  • Auto immune disorder characterized by acute paralysis due to damage to the peripheral nerve system possibly due to Campylobacter antibodies cross-reacting with nerve cells

We’ll hear about these from public health. Beware of contaminated meats (mostly chicken) & Raw milk.

Campylobacter species

• Most are microaerophilic and capnophilic

• Most are slow growing

Gram Stain

• Small, curved GNB….S shapes or ‘sea gull wings’

• Carbolfuschin counter stain improves GS

Urease Negative

Darting motility in fresh stool, Allegedly

Campylobacter jejuni ssp jejuni

Morphology

• BAP:  Gray to pink-tan flat colonies, moist, runny, spreading

Selective media – used to prevent overgrowth by faster growing enteric organisms

• Campy-BAP:  Brucella agar base, 10% sheep blood, antibiotics

• Skirrows media:  Columbia agar base, 7% horse blood, antibiotics

Grows best at 42C

Microaerophilic and capnophilic

Don’t like too much Oxygen, But not anaerobic

Campylobacter jejuni

ID

Identification

• Characteristic gram stain and motility

• Oxidase positive

• Catalase positive

• Hippurate hydrolysis positive

• Growth at 42C

• Nalidixic acid:  Susceptible

• Cephalothin:  Resistant

• MAC = no growth

Campylobacter jejuni

Disease States

Disease States

• Leading cause of diarrhea world-wide (self-limiting)

• As few as 500 organisms can cause enteric disease

• Penetrates the intestinal epithelium, multiplies and destroys cells causing diarrhea that contains RBCs and WBCs

Food contaminants are the major route of transmission. Dairy, unknown, and then poultry

Other Campylobacter sp.

C. Coli

• Grows at 42C

• Hippurate hydrolysis:  Negative

• Cephalothin:  Resistant

• Nalidixic Acid:  Susceptible

C. Fetus

• Animal pathogen

• Variable growth at 42C

• Hippurate hydrolysis:  Negative

• Cephalothin:  Susceptible

• Nalidixic acid:  Resistant

• Grows on MAC

These are uncommon and more commonly seen in vet clinics

Helicobacter pylori

General

• Associated with gastric, peptic, and duodenal ulcers

• Colonizes 20%-40% of adults in the United states

Possibility that groundwater is the source of infections

Person to person??

• Survives the highly acidic environment of the human stomach

• Produces urease which breaks down urea to ammonia and neutralizes stomach pH

Helicobacter pylori

Disease States

• Produces a low-grade inflammatory response

• Damaged tissue resulting in ulcers

• Continued damage has been associated with the development of gastric carcinoma

Difficult to treat

Helicobacter pylori

characteristics and identification

• Organism is strongly urease positive

• Usually detected using non-culture methods

• Presumptively identified from gastric biopsy specimen by testing for the presence of urea

Proteus miribilis is also urease pos

Helicobacter pylori

Id

• •Serologic testing also available—serum antibody test

• •Stool Antigen detection kits

• Also have Breath test that are available.

  • Given a pill with radioactive urea. If H. Pylori present, they are able to break it down into ammonium and blow into a balloon→ look for Co2