Exam B Flashcards
lysis centrifugation is used for…
Dealing with intracellular organisms or contaminated broths?
If a bacteria has mecA gene what would the antibiotic of choice be?
?
Antibiotics that are synergistic →
beta lactams + aminoglycosides
Recurrent fever →
Borrelia recurrentis
Which entero is pos for arginine?***
CIN bullseye colonies
Yersinia enterocolitica
OF results (if orgs use glucose etc.)
If both yellow →
fermentation
ex: Escherichia coli
OF result:
If open yellow and covered green →
oxidative
-Pseudomonas aeruginosa (nonfermenter)
Of result:
If both green →
non-saccharolytic
Which enterobacteria are positive for arginine?
-E. coli
-Entercoccus spp.
-Enterbacter spp.
-Mycobacterium hominis
-salmonella (triple pos)
CIN bullseye colonies is seen with…
Yersinia enterocolitica
What reagents are used for the nitrate test?
-reacts with sulfanilic acid (reagent A) and α-naphthylamine (reagent B)
and zinc dust (reagent C) if negative the first time.
-Reagent A + B = positive red color change
-Reagent A + B = negative no color change add Reagent C
-If no color change in Reagent C = positive
ONPG pos is what color?
Turns this color in the presence of?
Yellow
β-GALACTOSIDASE
how is chlamydia pneumoniae transmitted?
by coughing or sneezing, which creates small respiratory droplets that contain the bacteria.
Characteristics of stentotrophomonas maltophilia include:
a. Oxidase maltose, DNase positive, non-motile
b. Motile and oxidase negative (Possibly)
c. Motile; oxidase positive, oxidizes maltose (usually oxidase negative, but can be up to 20% positive)
d. Oxidase negative and no growth on macconkey
pseudomonas aeruginosa produces …
pyocyanin
resin bottles stop the effects of…
antibiotics/meds
Gram - rod isolated from wound infection that ferments lactose, produces acid slant and butt on TSI, oxidase +?
A. hydrophilia (Aeromonas hydrophilia) (Non-fermenter of lactose)
b. Campylobacter fetus (C. fetus)
C. V. cholera
(Considered a late lactose fermenter)
d. Campylobacter coli (C. coli)
C
Stenotrophomonas are oxidase ________ and motile _________
negative
positive
Stenotrophomonas oxidation?
glucose oxidizer (check this one)
Pseudomonas are positive for…
motility, glucose oxidizer, and oxidase.
Gram - rod, non glucose fermenter, that produces H2S found on wound?
?
What level of CO2 should CO2 incubators be at?
5-10%
Gram - bacilli, nitrate +, indole -, citrate +, MR +, urease -, H2S positive?
S. enteritidis
(distinguishing factor is H2S positive)
All species of Salmonella is citrate positive except __________
typhi
Salmonella paratyphi is H2S ________.
negative
E. coli is indole _________.
positive
E. sonneri is indole ___________.
positive
Aeromonas characteristics and lab results?
?
shewanella characteristics and lab results?
?
What does the MIC tell you?
determines the lowest concentration of an antimicrobial agent that can effectively inhibit the growth of a specific microorganism
MIC broth dilution
-
which bacteria has brick red fluorescence?
Prevotella and Porphyromonas
What organism is susceptible for SPS disc?
P. anaerobius
Differ between M.hominis and U.urelyticus?
M. hominis → small pinpoint colonies, (arginine positive)
U.urelyticus → urease +, large fried egg colonies,
If your RPR test is positive…
you will need more tests to confirm that you have syphilis → not specific enough
D-test is looking for…
inducible clindamycin resistance due to erythromycin being there
all the organisms that are H2S positive
Citrobacter (only lactose fermenter)
Salmonella (- urease)
Proteus (+ urease)
Urease positive organisms
Proteus
Klebsiella
Serratia
Moranella
‘Mnemonic – Uncle Pete Knitted Sweaters on Monday’
Citrobacter is urease…
variable
organisms that present as bipolar rods (safety pin)
Which shows bipolar staining
B. fragilis has safety pin appearance due to vacuoles
Yersinia (pestis) show bipolar staining
Yersinia enterocolitica has a _____________ appearance on CIN agar
bull’s eye
the full name of the lysine decarboxylase
LYSINE IRON AGAR
lysine decarboxylase test:
Full purple →
lysine decarboxylase***
lysine decarboxylase test:
Purple slant, yellow butt →
glucose fermentation
lysine decarboxylase test:
Yellow butt, red slant →
deamination of lysine
Proteus and Providencia
The Adv and Disadv to the broth dilution AST?
-
An incoulum on a Muller Hinton Kirby Bauer broth is equivalent to 2 MacFarland Standard. Which is true?
a. Zone is too large
b. Zone is too small
c. Zone is correct
d. Needs longer incubation
?
Bread crumb colonies…
Fusobacterium nucleatum (yellow)***
Black pigmented colony…
eptococcus niger → also Prevotella/Porphyromonas (have pigment)***
Pitted agar…
Eikenella corrodens
Brick red fluorescence…
Prevotella and Porphyromonas***
Ground glass colonies…
C. difficile (yellow ground glass colonial morphology)
“Molar tooth colony”
Actinomyces (older colonies)
“Sulfur granules”
Actinomyces
a man with dysuria and discharge coming out of his penis → discharge had WBCs but no bacteria
caused by…
Lymphogranuloma venereum
QC using Klebsiella oxytoca on an API strip test, shows all positive results except VP. What is the best course of action?
a. Return the api test b. reagent strips back to the manufacturer
Make new VP reagents and retest
c. Streak a new isolate of Klebsiella and retest
d. Report to supervisor about…
c. Streak a new isolate of Klebsiella and retest
How machines can tell if there is a pos blood culture or not?
-Turbidity
-color change, gas production, and colony formation
-Blood culture machines determine a positive by the change in CO2***
Anaerobic gram negative bacteria was detected from a neck abscess. The colonies looked like bread crumbs. What are the expected biochemical test results?
Susceptible to Kanamycin and colistin
What two organisms are resistant to all 3 antibiotic discs?
B. fragilis and Prevotella***
Prevotella is Bile Esculin ______.
negative
B. fragilis is bile esculin _______.
positive
Blood cultures:
only report bacteria that grow on BOTH bottles. If they only grow in one, they are most likely…
contaminants
Patient came in with a wound with dark pigment to it, what would the bacteria be?
?
Fusobacterium nucleatum?
?
Bacteria that has “pointed ends”
?
-In the GI tract
-Some members are indigenous microflora and can be opportunistic pathogens
-There are other bacilli in the GI tract that are NOT apart of this family
-Associated with various human diseases
(Abscesses,
GI tract infections,
Meningitis, Pneumonia,
Septicemia,
UTIs,
Wound infections)
Enterobacteriaceae
family
-Extra intestinal infections (occur outside the GI tract) – UTIs, respiratory infections, wound infections, bloodstream infections, and CNS infections
Is salmonella and Shigella indigenous microflora?
NO! ALWAYS PATHOGENIC
MOST COMMON causes of nosocomial infections
Enterobacteriaceae
MOST GI tract infections are caused by:
Escherichia
Salmonella
Shigella
Yersinia
Enterobacteriaceae:
NON MOTILE members include…
-Klebsiella
-Shigella
Enterobacteriaceae:
___________ fermenters.
glucose***
Enterobacteriaceae:
facultative _________.
anaerobes
True or false
Enterobacteriaceae are spore forming
false. Non-spore forming.
Enterobacteriaceae:
Catalase ___________.
positive – except Shigella dysenteriae
Enterobacteriaceae:
Oxidase __________.
negative – except Plesiomonas shigelloides.
True or false:
Enterobacteriaceae
capable of reducing nitrate to nitrite
true
Enterobacteriaceae:
capable of growing on ___________ agar.
MacConkey
Enterobacteriaceae:
Most members of the family are motile by _________ flagella.
peritrichous
Lactose Fermenters…
E. coli
Klebsiella
Pantoea
Enterobacter
Citrobacter
Serratia
Non-Lactose Fermenting…
Salmonella
Shigella
Proteus
Morganella morganii
Providencia
Yersinia
Non-lactose fermenters, motile, and produces H2S
Proteus
salmonella
Non-lactose fermenters, nonmotile, non-H2S producers
Shigella
yersina
Enterobacteriaceae Antigens.
O=
outer membrane
Enterobacteriaceae Antigens.:
H=
Flagella
Enterobacteriaceae Antigens.:
K=
capsule
Enterobacteriaceae Antigens.:
VI=
capsule of salmonella
What bacteria have swarming effect?
Proteus Swarming effect – P. mirabilis & P. vulgaris
