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Microbiology Lab - Midterm
Staphylococcus, Streptococcus, Neisseria, Corynebacterium, Listeria, Haemophilus
52
Microbiology
Undergraduate 4
02/02/2013

Additional Microbiology Flashcards

 


 

Cards

Term
[image]
Definition

Streptococcus pneumoniae

 

- alpha hemolysis

- Optochin susceptible

- aerotolerant anaerobes / obligate fermenters / some capnophiles (CO2)

- prefer BA plate

Term
[image]
Definition

Corynebacterium diphtheria

(w/ L. monocytogenes)

 

- can show BETA hemolysis (we didn't see any)

- on Tellurite, black growth

- facultative anaerobes

- slow growth (except on Loeffler's slant)

Term
[image]
Definition

Haemophilus influenzae

 

- requires X factor (heme) and V factor (NAD)

- therefore they must grow on CA or around Staph colonies

Term
[image]
Definition

H. parainfluenzae

 

- requires V factor only, so will grow around V strips all the way

- can look a lot like H. influenzae

- facultative anaerobes

Term
[image]
Definition

Listeria monocytogenes

 

- can show soft beta hemolysis (we didn't see)

- growth on tellurite is grey-black

- facultative anaerobe

Term
[image]
Definition

Staphylococcus aureus w/S. epidermis

 

- S. aureus: beta hemolysis, larger

- S. epidermis: no hemolysis, small

 

- facultative anaerobes

- hardy, salt-tolerant and drying-tolerant

Term
[image]
Definition

Staph. saprophyticus

 

- no hemolysis

- facultative anaerobe

Term
[image]
Definition

Strep pyogenes (Grp A)

 

- beta hemolysis 100% when anaerobic incubation

- aerotolerant anaerobe

- prefers BA plate

Term
[image]
Definition

Strep. agalactiae (Grp B)

 

- beta hemolysis

- aerotolerant anaerobe

Term
Acid-fast stain
Definition

- used to visualize mycobacteria, which have high MW lipid cell walls that repel gram staining, and are slow-growing

- mycobacteria show up as beaded, slender, pink rods, usually stuck together in clumps

Term
Novobiocin resistance
Definition

- used to differentiate S. saprophyticus from S. aureus and S. epidermis

- S. saprophyticus is the only one of these that is RESISTANT

Term
Coagulase test
Definition

- used to differentiate S. aureus from S. epidermis and

S. saprophyticus

- S. aureus is POSITIVE

Term
Catalase test
Definition

- used to differentiate between GPC

- Staph is catalase POS, and

Streps are all catalase NEG

Term
Beta Hemolysis
Definition

- complete lysing of RBCs

- exhibited by:

- Staph. aureus

- Strep pyogenes (A) - 100% when anaerobic incub.

- Strep agalactiae (B)

- Corynebacterium diphtheria (possible)

- Listeria monocytogenes (possible)

"Beta A DiffLisAur" (Strep B & A, Diph, List, S. aureus)

Term
Alpha hemolysis
- what tests could you use first to distinguish them?
Definition
- partial RBC lysis
- exhibited by:
Strep pneumoniae
viridans Streptococci

Tests you could do:
- catalase? if NEG, it's a strep...
- optochin test? if susceptible, it could be pneumo, and you should do bile solubility
to confirm. If it's resistant, it's viridans or other. You can stop here.

Term
NO hemolysis
Definition

exhibited by:

  • Staph. epidermidis, Staph. saprophyticus
  • Enterococcus
  • Neisserias & Moraxella (GC, MC, MX)
  • C. pseudodiphtheria
  • H. influenzae, H. parainfluenzae
Term
Normal microbiota
Definition
  • Staph aureus (nares)
  • Staph epidermidis (skin)
  • Strep pneumo (10-30% of throats)
  • viridans Strep
  • Enterococcus (fecal)
  • N. meningitidis (3-15% of URTs)
  • Moraxella catarrhalis
  • diphtheroids
  • L. monocytogenes (environmental & intestinal)
  • H. influenzae & parainfluenzae (URT)
Term
Facultative anaerobes
Definition
  • Staph spp.
  • C. diptheria & C. pseudo
  • L. monocytogenes
  • Haemophilus spp.
Term
Incubate in increased CO2
Definition
-Strep species (viridans, Pneumo, Enterococcus)
-Neisseria gonorrhea
-Neisseria meningitidis
(but not M. catarrhalis)
Term

Fastidious

(most to least)

Definition
  • N. gonorrhea (CA, CO2)
  • H. influenzae (X/V factor so CA), H. para (V only, still CA)
  • N. meningitidis (BA, CO2)
  • Strep Grp A, B, pneumo, viridans (BA preferred)
  • Enterococcus (aerotolerant, but hardier)
  • C. diphtheria (slow)
  • Staph. aureus / epidermidis, Listeria monocytogenes
Term
UTI
Definition
  • Staph. saprophyticus
  • Enterococcus
Term
Meningitis can be caused by...
Definition
  • Grp B Strep (neonatal)
  • Strep pneumoniae
  • N. meningitidis (hematogenous)
  • L. monocytogenes (rare, foodborne)
  • H. influenzae

Brains Have No Problem Listening!

Term
CSF sample
Definition

- taken from lumbar puncture / spinal tap

potential pathogens:

  • Grp B strep (neonates)
  • H. influenzae (young children)
  • N. meningitidis (children, young adults)
  • Strep pneumoniae* (older adults)
  • Listeria monocytogenes (rare)
Term
Wound specimen
Definition
- Staph aureus (abscesses, impetigo)
- Staph epidermis (occasional, often a contaminant but can be acq. nosocomial)
- Grp A Strep (necrotizing fasciitis; can be w/ or w/o S. aureus in erysipelas)
- Enterococcus
- diphtheroids (usually contaminants)
Term
Sputum specimen

- what types of cells to look for?
- what types of bacteria to look for?
- what type of contaminants to watch out for?

Definition
- should have PMNs in bacterial pneumonia infx

LOOK FOR:
- Strep. pneumoniae
- Staph aureus (tho could be normal microbiota)
- H. influenzae(tho could be normal microbiota)

Contaminants from mouth if improper collection:
- Neisseria
- viridans Strep
- or confusion w S. aureus / H. influenzae normal microbiota

Term

Bacitracin resistance

Definition
- used to differentiate Group A & B Strep
- Group B Strep is RESISTANT
Term

Optochin resistance

Definition
- used to differentiate between Streps

- viridans Streptococci are RESISTANT
while pneumococcus is Susceptible

Term

Bile esculin

Definition
[image]
Term
Enterococcus
- where found?
- nutrition r/t other Strep?
- infx where?
- tests?
Definition

- typical fecal microbiota

- they're aerotolerant anaerobes, but hardier

- can cause wound infx, sometimes UTI

- no hemolysis

- Catalase NEG (maybe pseudo)

- Bile Esculin POS (black on slant)

- NaCl 6.5% POS (color chg)

 can confirm

Term
viridans Streptococci
- what type of specimen?
- tests? colony morphology?
Definition
- often found in throat/mouth, so contaminates sputum specimens
- Catalase NEG
- alpha hemolytic, very tiny colonies
- Optochin resistant
- Bile Solubility - NEG
confirms it
Term
Strep. pneumoniae
- where?
- infx?
- distinctions?
Definition
- Throat microbiota of 10-30% healthy ppl
- Pneumonia* also Meningitis
 
- colonies have mucoid appearance, small, white, alpha hemolytic
- Catalase NEG
- Optochin susceptible
- to confirm do:
- Bile Solubility - POS (soluble)
Term

Bile Solubility

Definition

- used to differentiate Strep pneumo from other alpha-hemolytic Strep


- put a drop of sodium deoxycholate onto isolated colonies on a plate, and incubate 15 mins.

- Strep pneumo is Bile Soluble - these colonies should lyse and disappear
Term

Sodium hippurate test

Definition

- differentiates Grp B Strep from other Strep spp.

- positive test indicated by deep purple color after incubation and addition of ninhydrin reagent

 

- Grp B Strep is Sodium Hippurate POS

Term

Group B Streptococcus

- colony morphology

- tests

- where would you look for this

Definition
- incubate anaerobically for reliable beta hemolysis
- beta-hemolytic, colonies have slight orange pigmentation, small, creamy
- Catalase NEG
- Bacitracin RESISTANT
- Sodium Hippurate Hydrolysis - POS (purple)
(B is more HIP than A)

- look for in suspected neonatal meningitis

Term
Group A Streptococcus
Definition
- Strep throat, wounds, also think of post-Strep disease
- toxins!!!

- white colonies, remain intact when pushed w/loop
- Catalase NEG
- beta hemolysis
- Bacitracin susceptible
confirm serologically

Term
Oxidase Test
Definition
- few orgs are Oxidase pos (purple)
-The Neisserias

- M. catarrhalis

- tests for activity of cytochrome c oxidase (part of ETC of some bacteria)
- moisten filter paper with oxidase reagent, transfer test colony to paper and POS result is purple color change

Term
VCN media
Definition

- SELECTIVE media containing Abx that inhibit growth of organisms that might outcompete N. gonorrhea (it's a slow grower)

 

- V = vancomycin (for G+)
- C = colistimethate (for G-)
- N = nystatin (for yeasts)
Term
What organisms grow only on Chocolate agar?
Definition

- N. gonorrhoeae

- H. influenzae
(H. flu will also grow in satellite colonies around Staph)

Term
[image]
Definition

CTA slants (Cystine Trypticase soy agar)

- used to differentiate between N. gonorrhoeae,

N. meningitidis, and M. catarrhalis

- you'd use it if you had Oxidase POS organisms & you want to narrow it down

- color change from pink to yellow if positive

- Glu - GC & MC, but not MX

- Mal - MC only

- Lac - neither

- Suc - neither

Term

Moraxella catarrhalis

- growth and differentiation

Definition

- growth on NA, without CO2 incr

- sugar degradation test - NEG for all

 

- GC, MC and MX are all oxidase POS

Term

Strep pneumo

- hemolysis?

- Bile Solubility?

- Abx resistant / susceptible

Definition

- ALPHA hemolysis

- bile SOLUBLE

- optochin SUSCEPTIBLE

Term
[image]
Definition

Urease Test

- L to R: POS, NEG, NEG or not inoc

- tests for organisms ability to produce urease; urease hydrolyzes urea and releases NH3, raising pH of medium

- pH raised = more alkaline = pink result (POS)

- we use to differentiate between GPRs:

- C. pseudodiphtheria is Urease POS

- C. diphtheria & L. monocytogenes are Urease NEG

Term
Enterococcus vs. Group D Strep
- tests?
Definition
Enterococcus is bile-esculin POS + grows in 6.5% NaCl.

Group D Strep is bile-esculin POS, but does NOT grow in NaCl.

Term
[image]
Definition

Not inoculated

NG

A - C diph and L mono

AG

NC

- C. diphtheria  is (A) for Glu and Mal

- C. pseudo is (NC) for all

- L. mono is (A) for Glu and Mal

Term
Nitrate reduction test
Definition

- tests an orgs ability to reduce nitrate to nitrite, NO, N2O, N2

- nitrate A/B detect nitrite

- red color change after adding reagents A/B indicates (+) result.

- If no (+) result, add zinc, which tests for remaining nitrate

- if red color change results after adding zinc, we can conclude a (-) test

- Orgs that are (+) C. diph and C. pseudo (L. mono is negative)

Term
Metachromatic Granules
Definition
- can be visualized using methylene blue

- spirillum volutans

- C. diphtheria

Term
India Ink Stain
Definition
- used to see the capsule on bacteria

- Cryptococcus (yeast)

- Klebsiella

Term
Staph aureus infections?

Toxins?

Definition
- abscesses, wound infx, septicemia/bacteremia, pneumonia (rare)

- often nosocomial

Toxin-producing strains:

- food poisoning, TSS, SSSS

Term
Latex agglutination serogroups spp.
Definition
- Strep A/B
- N. meningitidis
Term
C. diphtheria
- where found? (is it normal)
- tests?
Definition
- throat in lesions (few carriers, and some strains are non-toxigenic)
- diptheroids themselves are very common, so lab should be looking specifically for diphtheria.
- beta-hemolytic (though can't always see it)
- GPR? Check for Listeria or Corynebacterium
Use four different tests:
- sugar ferments (Glu and Mal only w/acid)
- motility (-)
- urease (-)
- nitrate (+)
Term
Listeria monocytogenes
- where found?
- tests?
Definition
- blood or possibly CSF - if seen, lab must R/O Listeria
- GPR seen, colonies CAN be beta-hemolytic
- Use 4 tests to distinguish between other GPR:
- sugar fermentation (+)
- motility (+)
- urease (-)
- nitrate (-)
(LISTERine at NITe is NEGATIVE because you have no one to spend it on)
Term
Obligate fermenters
Definition
Enterococcus
Strep spp.
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