Bacteriology Exam 6 (Pseudo, Vibrio, Burkholderia) Flashcards
What do Vibrio, Aeromonas, and Chromobacterium spp. all have in common?
Oxidase positive, glucose fermenters, GNR
Habitat/epidemiology for Vibrio spp.
Brackish/marine water (salty)
Habitat/epidemiology of Aeromonas spp.
Freshwater or brackish/marine water with low salt content
Habitat/epidemiology for C. violaceum
soil or water most commonly in tropical and subtropical climates
What is the best system to identify Vibrio spp.? Why?
API 20E because the inoculum is prepared in 0.85% saline and Vibrio are halophilic organisms and tolerate salt
Aeromonas motility?
Motile
Aeromonas indole?
Positive
What temperature can Aeromonas grow at?
Wide range of temperatures: 0-42 C
What is Aeromonas usually associated with?
Untreated well water or consumption of seafood
What organism is most commonly found in wound infections after exposure to aquatic environments, especially on extremities, causing cellulitis?
Aeromonas sp.
What does aeromonas hydrophila complex cause?
GI illnesses (if ingested), UTIs, skin and soft tissue infections
How to differentiate Aeromonas spp from Yersinia enterocolitica since they are indistinguishable on CIN agar?
Aeromonas is oxidase pos
Yersinia enterocolitica is oxidase neg
Aeromonas hemolysis on BAP
Beta
How to differentiate Aeromonas spp from Plesiomonas spp?
Both oxidase pos, so look at hemolysis
Aeromonas = beta
Plesiomonas = gamma
Why is it hard to do oxidase testing on Chromobacterium violaceum?
Because it produces a violet pigment similar to that of an oxidase positive result
What will chromobacterium violaceum look like on MAC?
NLF so clear
What temperature does Chromobacterium violaceum grow at?
42 C
Chromobacterium spp. motility
Motile
What does Chromobacterium spp. colonies look like?
Violet pigmented colonies called violacein
T/F: Chromobacterium violaceum is the only species of Chromobacterium.
True
What is the pathogenesis of Chromobacterium violaceum?
Not associated with GI infections; but through contamination of wounds can lead to life threatening systemic infections.
Can cause rare opportunistic infections in patients with low neutrophil counts.
Hemolysis of Chromobacterium violaceum
Beta-hemolytic
Unique feature of Chromobacterium violaceum smell
produce an almond-like odor
How would you differentiate Aeromonas from Chromobacterium violaceum?
First, look at pigment of colonies.
If there is no violet pigment (9% of strains) C. violaceum is negative for lysine and ornithine and does not ferment maltose or mannitol.
How to differentiate Chromobacterium from Pseudomonas, Burkholderia, Brevundimonas, and Ralstonia?
Chromobacterium ferments glucose and has a positive indole test
C. violaceum is often resistant to ________ and _______.
beta-lactams and colistin
T/F: Most vibrio spp. require sodium for growth.
True
Vibrio spp. motility, catalase, oxidase
Motile, catalase neg, oxidase pos
Vibrio are temperature ________ and are found in water if the temp exceeds _____C.
sensitive; 20
What can increase the risk of Vibrio infection?
- Increased travel
- Increased consumption of seafood
- Increased use of recreational water facilities
- Immunocompromised
What type of infections can vibrio cause?
- Mild gastroenteritis
- Cholera
- Wound infections
- Fatal septicemia
- Necrotizing fasciitis
What are the four most common species of Vibrio?
cholerae
parahaemolyticus
vulnificus
alginolyticus
What is the gram stain of vibrio?
Small, curved gram negative rods that may be pleomorphic
Vibrio nitrate reduction?
Positive
Vibrio motility
Motile that exhibit rapid darting or shooting star motility
What is a special agar that Vibrio species may grow on? What will Vibrio look like on this agar? What does this mean?
TBCS agar; yellow or green colonies (yellow means ferments sucrose, green means does not ferment sucrose)
What is in TCBS agar that allows Vibrio to be selected for?
1% sodium chloride, bile salts to inhibit GP organisms, sucrose to differentiate between vibrio species, and high pH
Which species of Vibrio are lactose fermenters?
Only V. vulnificus (the rest are NLF)
What will V. parahaemolyticus look like on CHROM vibrio agar?
Mauve
What will V. vulnificus and V. cholerae look like on CHROM vibrio agar?
Green/turquoise blue
What will V. alginolyticus look like on CHROM vibrio agar?
Creamy white
What will Vibrio cholerae look like on TCBS agar vs Vibro parahaemolyticus?
Vibrio cholerae: yellow (ferments sucrose)
Vibrio parahaemolyticus: clear/green color of agar (does not ferment sucrose)
What are the only two Vibrio sp. that do not REQUIRE salt for growth, but will grow in 6% NaCl broth?
V. cholerae and V. mimicus
What test can be used to differentiate Vibrio from Aeromonas sp? How does it work? Which are pos and neg?
The string test - organisms are emulsified in 0.5% sodium deoxycholate which lyses Vibrio cells but not Aeromonas. Cell lysis releases DNA which is polymerized and pulled up into a string with an inoculating loop.
Aeromonas = neg
Vibrio = pos
How is vibro cholerae mainly spread?
contaminated water
What does vibrio cholerae cause?
Rapid fluid and electrolyte loss producing “rice water stool” frequently leading to death
What is the drug of choice for vibrio cholerae?
Tetracycline
What are the 2 subgroups of Vibrio cholerae capable of causing epidemic due to having the CT toxin?
V. cholerae O1 and V. cholerae O139
Which Vibrio sp is known to cause fatal septicemia, especially in patients suffering from an underlying liver disease?
Vibro vulnificus
How can V. cholerae toxin be detected in stool?
ELISA
What is Vibro vulnificus associated with?
associated with fisherman, fishing hook trauma
Which Vibrio can be found in people with liver disease?
V. vulnificus
What can Vibrio vulnificus cause?
Can cause septicemia and wound infections leading to cellulitis, necrotizing fasciitis, and can cause multiple organ failure
What does Vibrio parahaemolyticus cause and what can it be from?
Watery diarrhea; can be caused from eating raw and undercooked seafood, usually self-limiting
Can also be found in wounds, ear, and eye infections
What is the least pathogenic of the Vibrio spp?
Vibro alginolyticus
Vibrio alginolyticus salt requirements
Strict halophile; can tolerate up to 10% salt
What can Vibro alginolyticus cause or be a hazard for?
Can be a hazard for fisherman or sailors (but not as bad as vulnificans).
Nearly all originate from extraintestinal sources such as eye and ear infections, wound and burn infections
What are the only colorless colonies on TCBS agar? Why?
V. parahaemolyticus and V. vulnificus (they do not ferment sucrose)
V. vulnificus lactose fermentation
lactose fermenter
Which is the only Vibrio that does not require salt to grow?
V. cholerae and V. mimicus
What are common characteristics of Pseudomonas and Burkholderia sp?
GNR, Non-fermenters, Oxidase pos, Nitrate neg
Pseudomonas is a glucose ______.
oxidizer
For the O/F glucose test, if both closed and open tubes are green, what does that mean?
No use of glucose at all.
For the O/F glucose test, if both closed and open tubes are yellow, what does that mean?
Fermenter and oxidizer of glucose
For the O/F glucose test, if the open tube is yellow and the closed tube is green, what does that mean?
Oxidation of glucose, no fermentation of glucose
Pseudomonas and Burkholderia are all motile except for?
Burkholderia mallei
What temperature may Pseudomonas grow at?
42 C
Pseudomonas and Burkholderia oxygen requirements
aerobic
Pseudomonas catalase
Positive
Pseudomonas and Burkholderia glucose?
Oxidizers; not fermenters
Epidemiology of Pseudomonas and Burkholderia spp.
Environmental bacteria that survive well in aqueous environments
TSI slants; what does A stand for and what color will it be? what does K stand for and what color will it be?
A = acid (yellow color)
K = alkaline (red color)
What color is always underneath black (H2S) on a TSI slant?
Yellow (because gas was fermented)
What can Burkholderia cepacia cause?
pulmonary infection in CF patients; endocarditis, UTI, osteomyelitis in drug addicts
Where can Burkholderia cepacia be found?
in spas or contaminating eye drops
What is the special agar to detect B. cepacia in CF patients?
BCSA
What can grow on onions?
B. cepacia
What will B. cepacia look like on BCSA agar?
yellow, translucent, smooth to rough and slightly raised
B. cepacia oxidase
WEAKLY, slowly, oxidase positive
Burkholderia cepacia colony morphology
yellow/green pigments, rough nonwrinkled serrated edged colonies
Burkholderia notable biochemicals
Lysine +, Ornithine +, ONPG +, motile, oxidation of sugars
Where can you find B. pseudomallei?
soil, streams, ponds, and rice paddies
What medium is used to isolate B. pseudomallei? What will it look like?
Ashdown medium; it will appear violet
What does B. pseudomallei cause?
Melioidosis
What will B. pseudomallei’s gram stain look like?
Bipolar staining like safety pins
What will B. pseudomallei colonies look like?
Wrinkled, dry and green looking, metallic appearance with an earthy odor. Varying degrees of hemolysis
What temp does B. pseudomallei grow at?
42 C
B. pseudomallei notable biochemicals
Arginine +, oxidizes lactose, cetrimide negative
How can you distinguish B. pseudomallei from Pseudomonas since they are very similar in characteristics?
B. pseudomallei has no pyoverdin pigment
What is melioidosis and what organism causes this?
Aggressive granulomatous pulmonary diseased caused by inhalation ingestion or inoculation (pneumonia-like illness). Caused by P. pseudomallei
What disease and what organism is associated with returning Vietnam vets and S.E. Asian immigrants?
Melioidosis; B. pseudomallei
Notable features of B. mallei
Non-motile
Does not grow at 42 C
Causes severe infections in horses
What organism is likely if you were in close contact with a horse and are experiencing pulmonary-like infection?
B. mallei
What organism causes Glanders? What is it associated with?
B. mallei; infectious disease associated with horses, donkeys, and goats
What can Glanders cause in humans?
Transmitted from horses/goats by contact or inhalation and may cause septicemia, local infection with lymphadenopathy, acute pneumonia, or chronic disease
Common characteristics of Pseudomonas sp.
Motile, Catalase +, NLF, Strictly aerobic
What is the most encountered GNR outside of enterobacterales?
Pseudomonas aeruginosa
What are the three organisms associated with CF patients? How can you differentiate them?
B. cepacia, P. aeruginosa, and Stenotrophonomas maltophilia. S. maltophilia is oxidase negative, while the other two are positive.
P. aeruginosa exotoxin A function
kills host cells by inhibiting protein synthesis
P. aeruginosa Exoenzymes S and T function
disrupt cytoskeleton organization
P. aeruginosa elastases/phospholipase C function
destroying cells and tissues
Pseudomonas aeruginosa Pyocyanin function
damages cells by producing reactive oxygen species
Pseudomonas aeruginosa Alginate function
polysaccharide polymer that inhibits phagocytosis
What is quorum sensing in Pseudomonas aeruginosa?
When neighboring bacterial growth reaches a critical mass, quorum sensing allows P. aeruginosa to produce a biofilm due to alginate overproduction and can allow it to survive harsh environmental conditions
Where does P. aeruginosa typically infect?
The outer ear, the skin of swimmers or divers
What can P. aeruginosa cause?
Folliculitis, swimmer’s ear, hot tub rash, nail bed infections
How can P. aeruginosa be distinguished from other Pseudomonas?
Ability to grow at 42 C and production of pyocyanin and pyoverdin
What are the colors that Pseudomonas can show on BAP and MAC?
Pyocyanin - blue
Pyoverdin - Green
Pyorubrin - Red
Pyomelanin - Brown
Colony morphology of P. aeruginosa
Flat, feathered edge with metallic sheen
Beta hemolytic
Odor of grapes
Which organism has a polar flagella?
P. aeruginosa
Notable biochemicals of P. aeruginosa
Cetrimide +, Citrate +, Motile, Arginine +, Nitrate +, Oxidase and catalase +, Gelatinase production
What two pigments does P. aeruginosa produce? Which other organisms produce these pigments?
Pyocyanin - P. aeruginosa is the only one
Pyoverdin - also produced by P. fluorescens, P. putida
How can P. monteilii be distinguished from P. putida? How can both of these be distinguished from P. fluorescens?
P. monteilii does not oxidize xylose, P. putida does
P. fluorescens liquifies gelatin while both of those organisms do not
P. monteilii gelatin and xylose results
Gelatin negative
Xylose negative
P. putida xylose oxidation and gelatin liquification results
Gelatin negative
Xylose positive
P. mosselii gelatin and xylose results
Gelatin positive
Xylose negative
P. fluorescens gelatin and xylose
Gelatin positive
Xylose positive
Where can P. fluorescens and P. putida be isolated from?
Respiratory cultures, contaminated blood products, urine, cosmetics, hospital equipment, and fluids
P. fluorescens and P. putida identification
No growth at 42 C
Xylose oxidizers
Produce pyoverdin only
Oxidase positive
How to differentiate P. putida and P. fluorescens?
Gelatin hydrolysis
P. fluorescens is 100% gel positive
P. putida is 100% gel negative
Where is pseudomonas stutzeri isolated from?
Wounds, urogenital sources, septicemia, pneumonia
Colony morphology of Pseudomonas stutzeri
Wrinkled, leathery, adherent colonies that produce a light yellow or brown pigment
Pseudomonas stutzeri ADH test
Negative
What organism may be responsible for “sticky eye”? (aka conjunctivitis)
P. oryzihabitans
