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Microbiology 484 > Anaerobes > Flashcards

Anaerobes Flashcards

1
Q

Purpose of aerotolerance test

A

Both BAP & CNA plate should be used to differentiate between true anaerobes & capnophiles. Used to determine whether microbes are strict anaerobes or only facultative

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2
Q

Procedure of aerotolerance test

A

The same organism is placed on two plates - one is incubated aerobically, the other anaerobically. If only the anaerobe plate org grows, then anaerobe. If the org grew on aerobic and anaerobe, then aerobe

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3
Q

BBE agar

A

Selective/differential for Bacteroides fragilis

Turns black due to the org’s ability to hydrolyze esculin

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4
Q

EYA agar

A

Differential; used to detect lecithinase, lipase, & protease activity (Source from egg)

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5
Q

Nagler test

A

On EYA agar, C. perfringens antitoxin type A is smeared on 1/2 of the plate, then org is inoculated across both sides of plate. Pos test result is the lack of lecithinase activity on the half plate with antitioxin

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6
Q

What test has replaced the Nagler test?

A

Reverse CAMP test

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7
Q

Bacteriostatic effects of O2 on anaerobes

A

If O2 is introduced, the org is busy trying to reduce the molecular oxygen & uses energy that is needed for metabolism, so can’t reproduce = static growth

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8
Q

Bactericidal effects of O2 on anaerobes

A

Superoxide anions, hydroxyl radicals & hydrogen peroxide all build up, causing a cidal effect because anaerobes have few enzymes to effectively protect themselves from these byproducts

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9
Q

Why anaerobes need an environment that has a low redox potential? (media)

A

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

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10
Q

Why anaerobes need an environment that has a low redox potential (in vivo)

A

These sulfhydryl groups are provided by other “NF” that are present

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11
Q

Where anaerobes are located in the body

A

Skin, upper resp, female genital tract, GI tract

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12
Q

Where anaerobes are located in the environment

A

Soil, fresh & salt water

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13
Q
  1. Bacteroides fragilis
  2. Porphyromonas/Prevotella
  3. Fusobacterium nucleatum
  4. Clostridium species
  5. Actinomyces israelii
A

5 most commonly found anaerobes in infections

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14
Q

SPS disk

A

sodium polyanethol sulfonate

gm +c Peptostreptococcus anaerobius is susceptible

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15
Q

Nitrate disk

A

Nitrate -> nitrite

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16
Q

Bile disk

A

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

gram neg rod that’s 20% bile resistant is Bacteroides fragilis

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17
Q

Catalase

A

Clostridium: catalase =
Bacillus: catalase +

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18
Q

Gas liquid chromatography

A

Match peaks & time of peaks with known organisms

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19
Q

Biochemical based mini-systems

A

IDs in 24-48 hours

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20
Q

Enzyme based mini-systems

A

ID in 4 hours

Ex. Vitek, Rapid Ana II, Microscan

21
Q

C. botulinum food poisoning

A

Toxin produced by org is ingested in contaminated food & absorbed in small intestine. Toxin attaches to neuromuscular junction of affected nerves, causing paralysis along with other symptoms.

22
Q

C. perfringens food poisoning

A

Mild, self-limited GI tract. Illness approximately 8-12 hours after ingestion of contaminated food. Type C is more severe

23
Q

What anaerobe is responsible for pseudomembranous colitis?

A

C. difficile - caused by antimicrobial therapy or from hospital workers not washing hands

24
Q 
EYA lecithinase +
Nagler test: C +
Reverse CAMP +
Brucella/Blood Agar: double zone beta hemolysis
Gelatin hydrolysis & DNase pos
A

Presumptive ID for C. perfringens

25
Definitive ID for C. perfringens
Enzyme based mini-system
26
Actinomyces Eubacterium Lactobacillus
Non-spore forming anaerobic gram pos bacilli
27
Bifidobacterium Mobiluncus Propionibacterium
Non-spore forming anaerobic gram pos bacilli
28
Propionibacterium pathogenicity
NF of skin & can cause subacute bacterial endocarditis & bacteremia
29
``` Catalase + Spot indole + Anaerobic gram pos diptheroid Pleomorphic gram pos rod Gelatin hydrolysis pos ```
Presumptive ID of Propionibacterium
30
Actinomyces israllei
Seldom obligate anaerobes, colonies are rough, spider-like or wooly
31
Actinomyces israllei ID
Catalase, spot indole, & gelatin neg
32
Actinomycosis
chronic granulomatous infection with lesions that erupt from infected sinus & drain pus containing sulfur granules
33
Anaerobic gram neg bacilli
Bacteroides Prevotella Prophyromonas Fusobacterium
34
``` Catalase +/= Indole = DNase = Penicillin R Rifampin S Kanamycin R Pigment = Bile Solubility R ```
Bacteroides fragilis
35
``` Catalase = Indole + DNase = Penicillin S/R Rifampin S Kanamycin S Pigment = Bile Solubility S ```
Fusobacterium
36
``` Catalase = Indole + DNase = Penicillin S/R Rifampin S Kanamycin R Vancomycin S Pigment + Bile Solubility S ```
Porphyromonas
37
``` Catalase = Indole + DNase + Penicillin S/R Rifampin S Kanamycin R Vancomycin R Pigment + Bile Solubility S ```
Prevotella
38
Gram Pos Anaerococcus sp
Finegoldia spp Peporiphilus spp Peptococcus niger Peptostreptococcus spp
39
Gram neg anaerococcus
Veillonella
40
Presumptive peptostreptococci ID
anaerobic gram pos cocci
41
Peptostreptococcus anaerobius ID
SPS sensitive
42
Peptostreptococcus asaccharolyticus
SPS resistant
43
What is the genus of the anaerobic gram neg cocci?
Veillonella
44
Veillonella chemical ID
Gram neg cocci | Nitrate pos
45
CLSI suggestions for susceptibility testing
Not required for most anaerobic cultures except: 1. Known resistant organism 2. Failure of treatment 3. Very serius outcome 4. No literature available on empiric 5. Particular sites that warrant susceptibility testing 6. Particular organisms that warrant susceptibility testing
46
1. Penicilllin G 2. Broad spectrum penicillins (carboxy penicillins such as ticarcillin 3. Combination agent (B lactam antibiotic & B-lactamase inhibitor) 4. Other B-lactam antibiotics (cefoxitin & impenem) 5. Other: chloramphenicol, clindamycin, metronidazole, tetracycline, trovafloxicin
Common antimicrobial agents used
47
Problems encountered with Anaerobe susceptibility testing
1. Not all of them will grow on same media so reproducibility is poor 2. Relatively high costs 3. Lack of comparability between methods
48
Epsilometer test (E test)
Inhibition ellipse allows for an MIC & also several drugs (strips) can be used on one plate

Microbiology 484 (15 decks)

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