Other Fermenting GNRs Flashcards
Genera that are considered unusal fermenters
- Vibrio
- Aeromonas
- Plesiomonas
- Campylobacter
Inflammation of the stomach and intestines, resulting from bacterial toxins or viral infection and causing vomiting and diarrhea
Gastroenteritis
Infection of the intestines rsulting in severe diarrhea w/ the presence of blood and mucous in the feces
Dysentery
Stool specimen collection requirements
Stool or rectal swab has a 2 hour window if placed in a sterile cup
Stool specimen preservatives
- Cary Blair
- Buffered glycerol saline
- Alkaline peptone water
- Modified Stuart’s
Oxidase positive, fermenters of glucose, isolated in coastal areas (fresh, brackish, and salt water), associated w/ seafood consumption
Vibrio sp. characteristics
Describe vibrio morphology
- Curved, comma shaped GNRs,
- Polar flagella,
- Halophilic (requires Na)
Caused by Vibrio, spread by fecal-oral route, severity variable but usually severe diarrhea, death results from massive fluid loss/shock/acidosis
Cholera
Notorious pathogen, no tissue invasion, enterotoxin production (adheres to small intestine), “rice water” stools
Vibrio cholera
Treatment of cholera
- Fluid/electrolyte replacement
- Tetracycline in severe cases
Collection/transport requirements for stool/wounds (cholera)
Stool
- Susceptible to desiccation, w/in first 24 hours of infection
- Cary Blair at room temp (no buffered glycerol saline transport)
Wounds
- Sterile swabs
What do we use to isolate cholera?
- Thiosulfate Citrate Bile Salts Sucrose Agar (TCBS agar)
- SBA
- MAC
Describe TCBS agar
- Green plate
- Selective and differential
- Sucrose fermenters (yellow colonies) vs. non-sucrose fermenters (green colonies)
Hemolysis present on SBA from cholera
Beta
MAC results in cholera
Most lactose negative
Incubation requirements for cholera
Ambient air at 35C
What methods can we use to identify cholera?
- String test
- Vibriostatic test
- KIA and Phase II
- Automation
- MALDI-TOF
- O1 ro O139 antisera
List 3 non-cholera vibrios
- V. parahaemolyticus
- V. vulnificus
- V. alginolyticus
Endemic to Japan, mild gastroenteritis (ingestion of raw fish), wound infections (contaminated water), Kanagawa Phenomenon, does NOT ferment glucose
V. parahaemolyticus
More wound infections than diarrhea (contaminated seawater), septicemia, invasive, liver disease, non-sucrose fermenting
V. vulnificus
Wound infections, infections of ears and eyes, infrequently isolated in clinical laboratory, ferments sucrose
V. alginolyticus
Straight, coccobacillary GNR, polar flagellum, inhabitants of aquatic ecosystems (fresh and brackish); obtained from fresh produce, meat, and dairy products or exposure to aquatic source
Aeromonas sp
Causes gastroenteritis (mild watery, self-limiting diarrhea, spring to fall seasons) and extraintestinal infections
Aeromonas sp
Specimen collection and transport for Aeromonas sp
Stool: Cary-Blair or buffered glycerol saline as transport; process w/in 2 hours
Wounds: sterile swabs
Media to isolate Aeromonas
SBA, MAC, CIN, KIA and Phase II, automation, MALDI-TOF
Oxidase positive, fermenter, vibriostatic agent of O129 test, inability to grow in 6% NaCl
Aeromonas sp
CIN media characteristics
Cefsulodin-irgasan-novobiocin (CIN)
- inhibits normal flora in stool
Straight GNR, single species (one organism), polar flagellum, ubiquitous natural habitat in soil and fresh water, oxidase positive, glucose fermenter, lysine/ornithin/arginine positive
Plesimonas shigelloides
Causes gastroenteritis (mild, chronic, or invasive), extraintestinal infections
P. shigelloides
Isolation of P. shigelloides
SBA or MAC (enteric media)
Curved or S-shaped, seagull wing GNRs, polar flagellum, microaerophilic and capnophilic (37-42C), normal habitats in GI tracts of poultry, dogs, cats, sheep, cattle,a nd humans; zoonotic (animal to human)
Campylobacter sp
Causes gastroenteritis (C. jejuni), transmitted by contaminated food, self-limiting (similar to acute appendicitis), late summer/early fall occurrence, most common enteric pathogen
Campylobacter sp
Cuases febrile systemic disease (Guillain-Barre’s syndrome) and periodontal disease
Campylobacter sp
Methods to isolate and identify Campylobacter
Selective blood-based media (Campy-CVA) or charcoal-based (CSM); incubate at 42C, 5% O2, 10% CO2, 85% N for 48 hours
Hippurate hydrolysis positive, oxidase positive, catalase positive, curved GNR
Campylobacter sp
Spiral shaped GNR, natural habitat is human gastric mucosa (Dr. Barry Marshall’s experiment)
Helicobacter pylori
Causes gastric and duodenal ulcers, peptic ulcer disease, and gastric cancer, rarely found in stool specimens
Helicobacter pylori
Diagnosed by Ag detection, biopsy, urease testing, brucella agar w/ 5% horse blood, and ELISA tests for IgG
Helicobacteri pylori
