Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbiology > Anaerobes > Flashcards

Anaerobes Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Explain the purpose and procedure for the aerotolerence test:

A

Both a BAP and CHOC plate should be used to determine whether microbes are strict anaerobes or only facultative. The same org. is placed on two plates and incubated aerobically and anaerobically.

Only anaerobe plate grows - anaerobe
Both plates grow - facultative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the purpose and principle of BBE agar and EYA agar and the important anaerobe involved?

BBE:

EYA:

Describe reaction if org has: Lecithinase C-

 Lipase C-

 Protease C -
A

BBE: Bacteroides Bile - Esculin Agar, selective/differential - Bacteroides fragilis, Turns black due to the orgs ability to hydrolyze esculin

EYA: Egg Yolk Agar - CDC Formation, differential C used to detect lecithinase, lipase, and protease activity

If org has:

Lecithinase - makes media opaque around the growth streak
Lipase - Sheen on or around the colonies
Protease - Clearing of the agar around the streak

Commonly for Clostridium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Explain the historical significance of the Nagler test and the test that has replaced this test:

A

On the EYA agar, C. perfringens antitoxin type A is smeared on 2 of the plate and the org. is inoculated across both sides of the plate. A pos test result is the lack of lecithinase activity on the half plate with the antitoxin.

A reverse CAMP test is performed by some labs. Arrow points the opposite direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the bacteriostatic and bactericidal effects of O2 on anaerobes?

Bacteriostatic:

Bactericidal:

A

Bacteriostatic: If O₂ is introduced the org is busy trying to reduce the O₂ and uses energy that is needed for metabolism, so can’t reproduce = static growth rate

Bactericidal: Superoxide anions, hydroxyl radicals and H₂O₂ all build up causing a tidal effect because anaerobe orgs have few enzymes to protect themselves from these byproducts of O₂

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why do anaerobes need an environment that has a low redox potential?

Media-

In vivo (body)-

A

Media- there are certain anaerobic growth enzymes that require fully reduced sulfhydryl groups to be present to sustain life

In vivo (body)- sulfhydryl groups are provided by other normal flora that are present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where are anaerobes located in/on the body in their environment?

Body

Environment

A

Body - all NF colonizes sites: skin, upper resp., female genital tract, GI tract

Environment - Soil, fresh and salt water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

List the 5 most commonly found anaerobes in infections, along with their gram stain and morphology:

A
  1. Bacteroides fragilis (gram neg rod)
  2. Porphyromonas/Prevotella (pigmented, gram neg rod)
  3. Fusobacterium nucleate (gram neg rod)
  4. Clostridium species (gram pos rod)
  5. Actinomyces israelii (gram pos rod)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Discuss the following methods for the presumptive ID of anaerobes. Be specific about the differences between aerobic and anaerobic methodologies:

2) SPS Disk

A

Sodium polyanethol sulfonate

-Peptostreptococcus anaerobius is suscepetible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Discuss the following methods for the presumptive ID of anaerobes. Be specific about the differences between aerobic and anaerobic methodologies:

3) Nitrate disk

A

Nitrate to nitrite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Discuss the following methods for the presumptive ID of anaerobes. Be specific about the differences between aerobic and anaerobic methodologies:

4) Bile disk

A

to test if org can grow in 20% conc. of bile

-Gram neg rod (20%) bile resistant is B. fragilis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Discuss the following methods for the presumptive ID of anaerobes. Be specific about the differences between aerobic and anaerobic methodologies:

5) Catalase

Clostridium-

Bacillus-

A

Clostridium- Cat neg

Bacillus- Cat pos

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Discuss acceptable automated or biochemical procedures for definitive identification of anaerobes:

A
  1. Gas liquid chromatography match peaks and time of peaks with known organisms
  2. Biochemical based mini-systems 24-48 hrs
  3. Enzyme base mini-systems can read in 4 hrs. Ex: vital, rapid ana II, MICROSCAN rapid anaerobe
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe clostridial food poisoning caused by C. botulinum and C. perfringens:

C. botulinum

C. perfringens

A

C. botulinum - botulinum toxin produced by the org is ingested in contaminated food and absorbed in SI. It attached to neuromuscular junction of affected nerves causing paralysis which can appear from 2 hrs to 8 days. Antitoxin is used for treatment. Spores most often found in honey can cause infant botulism

C. perfringens - Mild, self limited GI tract illness approximately 8-12 hrs after ingestion of contaminated food. Type C is by far more severe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What anaerobe is responsible for pseudomembranous colitis? What is the most likely reason for this occurring?

A

C. difficile

Following antimicrobial therapy or from hospital workers not washing hands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe both colony morphology and gram stain morphology of Clostridium perfringens:

A

Large gram pos rods (gram variable)

Double zone of beta hemolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How would you identify C. perfringens?

Presumptive:

Definitive:

A

Presumptive: Egg yolk agar shows lecithinase pos
Nagler test is pos, Reverse CAMP test pos, Brucella/Blood agar - double zone beta hemolysis, Gelatin hydrolysis and DNase pos

Definitive: enzyme base mini-system

17
Q

List the non-spore forming anaerobic gram positive bacilli:

A 
Actinomyces
Eubacterium
Lactobacillus
Bifidobacterium
Mobiluncus
Propionibacterium
18
Q

Identify Propionibacterium and Actinomyces israllei by their chemical reactions, morphology and clinical pathogenicity. Which one is considered anaerobic diptheroids?

Propionibacterium

Actinomyces israllei

A

Propionibacterium: Normal skin flora and can cause subacute bacterial endocarditis and bacteremia and some species of actinomycosis. Presumptive ID: Cat pos, Spot indole pos, anaerobic gram pos diphtheroid, pleomorphic gram pos rod, gelatin hydrolysis pos.

Actinomyces israllei: seldom obligate anaerobes, colonies are rough spider like or wooly, Cat/spot indole/gelatin neg

19
Q

Compare and contrast actinomycosis and myonecrosis and the organisms responsible for each:

A

Chronic granulomatous infection with lesions that erupt from infected sinus and drain pus containing sulfur granules and is caused by Actinomyces

Myonecrosis is a condition of necrotic damage, specific to muscle tissue. It is often seen in infections with C. perfringens

20
Q

List the anaerobic gram negative bacilli by genus:

A

Bactericides
Prevotella
Porphyromonas
Fusobacterium

21
Q

Bacteroides fragilis

Catalase:
Indole:
DNase:
Penicillin:
Rifampin:
Kanamycin:
Vancomycin:
Pigment:
Bile Solubility:
A 
Catalase: +/=
Indole: =
DNase: =
Penicillin: R
Rifampin: S
Kanamycin: R
Vancomycin: none
Pigment: =
Bile Solubility: R
22
Q

Fusobacterium

Catalase:
Indole:
DNase:
Penicillin:
Rifampin:
Kanamycin:
Vancomycin:
Pigment:
Bile Solubility:
A 
Catalase: =
Indole: +
DNase: =
Penicillin: S/R
Rifampin: S
Kanamycin: S
Vancomycin: none
Pigment: =
Bile Solubility: S
23
Q

Porphyromonas

Catalase:
Indole:
DNase:
Penicillin:
Rifampin:
Kanamycin:
Vancomycin:
Pigment:
Bile Solubility:
A 
Catalase: =
Indole: +
DNase: =
Penicillin: S/R
Rifampin: S
Kanamycin: R
Vancomycin: S
Pigment: +
Bile Solubility: S
24
Q

Prevotella

Catalase:
Indole:
DNase:
Penicillin:
Rifampin:
Kanamycin:
Vancomycin:
Pigment:
Bile Solubility:
A 
Catalase: =
Indole: +
DNase: +
Penicillin: S/R
Rifampin: S
Kanamycin: R
Vancomycin: R
Pigment:+
Bile Solubility: S
25
Q

List the anaerobic cocci:

Gram positive-

Gram negative-

A

Gram positive-

Anaerococcus sp.
Finegoldia sp.
Peporiphilus sp.
Peptococcus niger
Peptostreptococcus spp.

Gram negative-

Veillonella

26
Q

Identify Peptostreptococci by clinical reaction, morphology and chemical pathogenicity: (P. Anaerobius vs. P asaccharolyticus)

A

Presumptive:
Anaerobic gram pos cocci, SPS sensitive (Peptostreptococcus anaerobius),

SPS resistant, indole pos is P. asaccharolyticus

27
Q

What is the genus of the anaerobic gram negative cocci?

A

Veillonella

28
Q

Identify Veillonella by chemical reactions, morphology and clinical pathogenicity:

A

Presumptive: Anaerobic gram neg cocci, nitrate pos

29
Q

What are the CLSI (Clinical Laboratory Standards Institute) suggestions for susceptibility testing?

A

Not required for most anaerobic cultures except:

  1. known resistant orgs
  2. failure of treatment
  3. very serious outcome
  4. no literature available on empiric
  5. particular sites that warrant susceptibility testing
  6. particular orgs that warrant susceptibility testing
30
Q

List the common antimicrobial agents used and example of each:

A
  1. penicillin G
  2. Broad - spectrum penicillins (carboxyl penicillins such as ticarcillin)
  3. Combination agent
    - B lactam antibiotics and a B-lactamase inhibitor Ex: amoxicillin/clavulanate
  4. Other b-lactam antibiotics Ex: ceroxitin and imipenem
  5. Other: Chloramphenicol, clindamycin, metronidazole, tetracycline, trovafloxicin
31
Q

List some problems encountered with anaerobe susceptibility testing and discuss the epsilometer test (E test):

A

Problems:

  1. Not all of them will grow on same media so reproducibility is poor
  2. Relatively high costs
  3. Lack of comparability between methods

Epsilometer Test:
E test - inhibition ellipse allows for an MIC and also several drugs (strips) can be used on one plate

CLSI describes two methods:

  • Reference agar dilution procedure
  • Macro dilution procedure for B. fragilis
32
Q

Obligate anaerobes vs facultative organisms

A

Obligate - organism which can only live in environments which lack oxygen

Facultative - Can live with or without oxygen

Microbiology (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions