HSC 308 Exam 5- Vibrio, Aeromonas, Plesiomonas, Campylobacter ch 20

Vibrio: Vibrio cholerae

causative agent of Cholera, often in epidemics, 01 strains, Classic and El Tor strains associated with epidemics; found in fresh, brackish, salt water

Cholera symptoms

Acute diarrhea with “rice water stools” large loss of fluids and electrolytes causes life-threatening dehydration, hypovolemic shock, metabolic acidosis.

Treatment: Fluid and electrolyte replacement; antibiotics.

Risk factors

(all increasing) Travel to coastal or endemic areas; Water recreation and exposure; Immunocomp population increasing; consuming raw or undercooked seafood, and improper handling, esp. shellfish.

Temperature effects

Vibrio more active in warm water & summer months, found in fish and shellfish; in winter found in seabed sediments – (in months with “R”)

Enterotoxin = “choleragen”

causes accumulation of cAMP along cell membranes, stimulates hypersecretion of water & electrolytes out of cells into intestinal lumen.

Vibrio parahaemolyticus

“summer diarrhea” in Japan, but found worldwide including coastal US; food-bourne outbreaks caused by contaminated seafood, esp. raw oysters

Symptoms: watery diarrhea, abdominal cramps, vomiting, also aquatic wound infections

Vibrio vulnificus

Coastal US, “Lactose positive Vibrio,” acquired from contaminated seafood, esp. Oysters, also found in aquatic wounds; Pts. can develop septicemia w/in hrs, with mortality rate of 40-60%, esp. with increased serum Fe, as in liver dysfunctions; recently made a public health reportable disease

Vibrio alginolyticus

most infrequent – least pathogenic, mostly external aquatic wounds, commercial and hobby fisherman, sailors, fish tank enthusiasts 

Vibrio gram stain

curved gnb; culture to SBA, MAC, TCBS agar, Lac neg - except V.vulnificus,

Motile; Reduce nitrate to nitrite, facultative anaerobes, grows in 6.5% salt broth

Oxidase pos – differentiate from Enterobacteriaceae

Able to ferment sugars – differentiate from Pseudomonas

Vibrios = susc to vibriostatic disk O/129; Pos string test - separates from Aero & Plesio

Aeromonas

 GNB; Motile, Oxidase +, ferment glucose, most species ferment lactose.

Don’t’ grow in salt broth; Indole pos

Found in water environments, contaminated drinking water and seafood, increased infections in summer, also found in animals: reptiles, mammals; also linked to contact lens soln. infections

Symptoms: gastroenteritis – acute dysentery, chronic diarrhea, cholera-like disease, wound infections common, septicemia, outbreaks after Hurricane Katrina, and Thailand tsunami of 2004,

Plesiomonas: Only Oxidase pos member of Enterobacteriaceae

Only Oxidase pos member of Enterobacteriaceae; GNB; glucose fermenter, Motile, can’t grow in salt broth; found in contaminated water, soil, also animal sources, seafood; causes water diarrhea; also wound infections from water sports, Vets and zookeepers infected by handling animals, esp. reptiles,

Oxidase pos – differentiate from Enterobacteriaceae, (but often mistaken as Shigella)

Sensitive to Vibriostatic disk – differentiate from Aeromonas

Can’t grow in salt broth – differentiate from Vibrios

Inositol fermentation = Plesiomonas

Grows on SBA, CHOC, not on MAC; can grow on special media (IBB)

Campylobacter jejuni

microaerophilic, capnophilic, GNB with “Seagull Wing,” culture looks “runny,” incubates at 42C, requires campy plate, Oxidase+, Catalase +, nonfermenter; most common diarrheal disease worldwide, causes bloody diarrhea with abdominal cramps, fever, chills; self-limiting;  from exposure to animal carriers, contaminated water; linked to undercooked poultry, esp. chicken, possible cause of Guillain-Barre.

Helicobacter pylori

causes gastritis, a leading cause of ulcers, lives in stomach & survives Stomach acid by making urease to breakdown urea to ammonia – neutralizes pH.  Linked to stomach cancer; Not cultured for: Detect with stomach biopsy, CLOtest with Christensen’s agar turns color if pos, also breath test available.