PSEUDOMONADS, ACITENOBACTERS, UNCOMMON GRAM-NEGATIVE BACTERIA Flashcards
- The green-to-yellow color change on Burkholderia colonies on
the OFPBL agar is primarily because ~ *
a) alkaline pH caused by the breakdown of pyruvate
b) acidic pH caused by the utilization of lactose
c) alkaline pH caused by the utilization of lactose
d) acidic pH caused by the breakdown of pyruvate
Answer: b. acidic pH caused by the utilization of lactose
Burkholderia cepacia complex colonies on (left) OFPBL agar,
which color change green to yellow because of the acidic pH
caused by utilization of lactose, and on (right) Pseudomonas
cepacia (PC) agar, which color change yellow to pink because of
the alkaline pH caused by the breakdown of pyruvate.
- This medium is used to isolate B. pseudomallei when
melioidosis is suspected
a) Ashdown medium
b) OFPBL agar
c) Burkholderia cepacia agar
d) Pseudomonas cepacia agar
Answer: a. Ashdown medium
Ashdown medium is used to isolate B. pseudomallei when
melioidosis is suspected and may take up to 96 hours for growth to
appear
- Identification scheme for Pseudomonas aeruginosa involves the following, EXCEPT:
a) Oxidase-positive
b) Triple sugar iron slant with an alkaline/no change
reaction
c) Production of pyocyanin, pyoverdin, pyrorubin or
pyomelanin pigments
d) Oxidase-negative
Answer: d. Oxidase-negative
Pseudomonas aeruginosa
-a convenient and reliable identification scheme for P. aeruginosa
involves the following:
Oxidase-positive
Triple sugar iron slant with an alkaline/no change (K/NC)
reaction
Production of bright bluish (pyocyanin), green
(pyoverdin), red (pyrorubrin), or brown (pyomelanin)
diffusible pigment on Mueller-Hinton agar or trypticase
soy agar
- A non-fermentative organism is isolated from a 48-hour culture plate. You suspect this to be ~ *
a) Burkholderia mallei
b) Burkholderia cepacia
c) Pseudomonas aeruginosa
d) Pseudomonas putida
Answer: b. Burkholderia cepacia
B. cepacia should be suspected whenever a non-fermentative
organism that decarboxylates lysine is encountered.
- detectable growth on 5% sheep blood agar and chocolate agars,
incubated at 35 ° C in carbon dioxide or ambient air, generally
occurs 24 to 48 hours after inoculation
- growth on MacConkey agar incubated in ambient air at 35 ° C
occurs 24 to 48 hours after inoculation
- Pseudomonas putida can be distinguished from P. flourescens by ~ *
a) their ability to liquefy gelatin
b) their ability to oxidize xylose
c) their inability to liquefy gelatin
d) their inability to oxidize xylose
Answer: c. their inability to liquefy gelatin
P. putida - can be distinguished from P. flourescens by their
inability to liquefy gelatin
- These microorganisms appear as gram-positive because they
resist alcohol decolorization.
a) Acinetobacter
b) Burkholderia
c) Stenotrophomonas
d) Pseudomonas
Answer: a. Acinetobacter
In gram staining, Acinetobacter species – plump coccobacilli that tend to resist alcohol decolorization, thus appearing as gram-positive
- The following correctly describe the Acinetobacter spp. *
a) Lactose fermenter on blood agar
b) Non-lactose fermenter on MacConkey agar
c) Produces lavender to light purple pigment
d) Some genospecies are beta-hemolytic
e) growth on 5% sheep blood agar when incubated at 5
degC
Answer: b. Non-lactose fermenter on MacConkey agar
Acinetobacter species are non-lactose fermenter on blood agar;
non-lactose fermenter on Mac but colonies exhibit a purplish hue
that may cause the organism to be mistaken for Lactose
Fermenter; some genospecies are beta-hemolytic
- This species can produce biochemical profiles similar to those of
Burkholderia cepacia *
a) Steotrophomonas maltophilia
b) Psedomonas aeruginosa
c) Acenitobacter
d) E. coli1:25,999
Answer: a. Steotrophomonas maltophilia
Steotrophomonas maltophilia - oxidase-negative, non-fermentative
gram-negative bacillus that can produce biochemical profiles
similar to those of Burkholderia cepacia
Pseudomonas and Nonfermenting and Misc. Gram-negative bacilli
may or may not grow on MacConkey
don’t ferment sugars
some oxidize saccharolytic sugars
oxidase positive
TSI slants K/K (nonfermenters)
use O/F media
Nonfermenting means it doesn’t ferment _______
glucose
Pseudomonas and Nonfermenting (source)
found in environment (soil, water, plants)
lots of nosocomial infections
prefer moist environments (nebulizers, catheters, etc.)
rarely part of normal flora
Pseudomonas and Nonfermenting (treatments)
can withstand chlorohexidine and ammonium cleaning products
resistant to multiple antibiotics
Pseudomonas and Nonfermenting (clinical infections)
usually in hospitalized patients
septicemia
meningitis
osteomyelitis
wound infections
Three clinically important bacteria of group
Pseudomonas aeruginosa
Acinetobacter species
Stenotrophomonas maltophilia
fluorescent group
grape-like odor, blue-green hue, beta-hemolytic
oxidase + and catalase +
oxidizes carbohydrates
Pseudomonas aeruginosa
