Anaerobe Introduction Flashcards
1
Q
A bacterium that is able to replicate w/o O2
A
Anaerobe
2
Q
Anaerobes often require a ____ redox potential
A
Low
3
Q
3 types of anaerobes
A
- Strict obligate anaerobes
- Moderate obligate anaerobes
- Aerotolerant anaerobes
4
Q
3 types of aerobes
A
- Facultative anaerobe
- Microaerophile
- Obligate aerobe
5
Q
Strict obligate anaerobes
- 2 facts about O2
- 2 examples
A
- Extremely sensitive; killed by O2
- Clostridium novyi, C. haemolyticum
6
Q
Tolerate moderate exposure to O2; requires an anaerobic environment for growth
A
Moderate obligate anaerobes
7
Q
Example of a moderate obligate anaerobe
A
Bacteroides fragilis
8
Q
Able to tolerate exposure to O2; able to grow more slowly in presence of O2, grows best in anaerobic environment
A
Aerotolerant anaerobes
9
Q
3 examples of aerotolerant anaerobes
A
- Clostridium tertium
- Clostridium carnis
- Clostridium histolyticum
10
Q
Grows under aerobic and anaerobic conditions; classified as an aerobe
A
Facultative anaerobes
11
Q
2 examples of facultative anaerobes
A
- E. coli
- Staphylococcus sp.
12
Q
Need reduced O2 (5%) and increased CO2 for growth
A
Microaerophiles
13
Q
Example of a microaerophile
A
Campylobacter sp
14
Q
Requires O2 and usually don’t grow under anaerobic conditions
A
Obligate aerobes
15
Q
2 examples of obligate aerobes
A
- Pseudomonas spp
- Micrococcus spp
16
Q
Where can anaerobes be found as normal flora?
A
- Nose
- Mouth
- Oropharynx
- Vagina
- Gastrointestinal tract
- Skin
- Colon
- Soil
- Freshwater/saltwater sediments
17
Q
In the colon, ____ outnumber facultative anaerobes 1000:1
A
Anaerobes
18
Q
Most anaerobic infections are ____ infections caused by trauma to kin or mucus membranes
A
Endogenous
19
Q
____ infections are usually by spore forming GPRs and often from soil or ingetsion of contaminated food
A
Exogenous
20
Q
Infections are most often ____; containing multiple anaerobes
A
Polymicrobial
21
Q
Factors that predispose a person to anaerobic infections
A
- Vascular stasis
- Human/animal bite wounds
- Aspiration of oral contents into lungs after vomiting
- Tooth extraction
- Oral surgery
- Puncture of oral cavity
- GI tract surgery or traumatic puncture of bowel
- Genital tract surgery or traumatic puncture of genital tract
- Introduction of soil into a wound
22
Q
List acceptable specimens for anaerobic cultures
A
- Needle aspirates at active site of infection, tissue, blood (anaerobic blood culture bottle)
- Lower respiratory specimens
- Normally sterile body fluids
- Stool (only for C. difficle)
23
Q
List unacceptable specimens for anaerobic culture
A
- Voided urine
- Upper respiratory specimens
- Stool (except for C. difficle)
- Vaginal or cervical
- Surface wounds
- Swabs are NOT appropriate (usually)
24
Q
Direct smear microscopic evaluation may present w/ what two signs?
A
Polymicrobial and pleomorphic
25
Characteristics of myonecrosis (gangrene)
- Absence of inflammatory cells (WBCs)
- Large GPRs
- Gas
- Possible spores
26
All primary plates should have these 3 requirements for anaerobes
- Vitamin K
- Hemin
- Yeast extract
27
Prior to inoculation what should be done to media?
- Stored at room temperature
| - Pre-reduced (ensures redox potential stays low)
28
After inoculation, media should be stored in a holding chamber for less than ____ _____ or placed in the anaerobic chamber immediately
1 hour
29
List 5 reducing agents that can be added to media to maintain an anaerobic environment
- Enriched thioglycollate (THIO)
- Chopped meat
- Serum
- Cysteine
- Rumen fluid
30
What does PRAS stand for?
Pre-Reduced Anaerobically Sterilized
| - Made w/ no O2 exposure and sealed in O2-free tubes
31
Purpose of ABAP
Anaerobe blood agar plate; non-selective
32
Purpose of PEA
Phenylethyl alcohol; anaerobe blood agar; selective; supports Gram positive
33
Purpose of PV, KV, and LKV
Paromomycin-Vancomycin; Kanamycin-Vancomycin; and Laked Blood Vancomycin; selective isolation of Gram negative anaerobes
34
Purpose of BBE
Bacteroides Bile Esculin; supports growth of bacteroides (selective); media turns black w/ esculin hydrolysis (differential)
35
Ambient air incubation conditions
| - % O2 and CO2
21% O2, 0.03% CO2
36
CO2 incubation conditions
| - % O2 and CO2
15-21% O2, 5-10% CO2
37
Microaerophilic incubation conditions
| - % O2 and CO2
5% O2, 10% CO2
38
Anaerobic incubation conditions
| - % O2 and CO2
0% O2, 5-10% CO2
39
List 3 anaerobic systems used in lab to maintain anaerobic conditions
- Anaerobic chamber (glove box)
- Anaerobic jars
- Anaerobic bags and pouches
40
5 advantages of using an anaerobe chamber
- Specimens are never exposed to O2 during set up
- Plate is observed as often as desired
- Incubator option
- Large volume cultures
- Gloves allow for O2 introduction
41
4 disadvantages of using an anaerobe chamber
- Cumbersome
- Airlock
- Space
- Contamination
42
4 anaerobe chamber requirements
- Catalyst
- Desiccant
- Oxidation reduction indicator
- Anaerobic gas (5% H2, 5-10% CO2, 85-95% N2)
43
Removes residual O2, often composed of palladium coated aluminum pellets
Catalyst
44
Used to absorb water; may be a silica gel
Desiccant
45
CO2 needed for the growth of many anaerobes and inert ____ is used as filler for remaining % of anaerobic atomosphere
N2
46
Used to verify daily that anaerobic conditions are maintained, can use indicator such as methylene blue or resazurin
Oxidation reduction indictator
47
Useful for small labs w/ SMALL anaerobe VOLUME
Anaerobic jars
48
Anaerobic jars must be incubated for ____ hours b/c especially susceptible
48 hours
49
Disadvantages of anaerobic jars
Cannot provide all advantages of a chamber, cost analysis over time shows chamber is better, plates must be removed from jar in order to examine and process
50
Advantages of anaerobic bags and pouches
Transport of organisms, plates can be examined w/o removal from bag
51
Gas liquid chromatography
| - 2 forms of extraction
1. Ether extraction (most common); short chain volatile acids
2. Chloroform extraction; organic acids non-volatile
52
Media used to grow anaerobes for gas liquid chromatography
PYG broth (peptone yeast extract glucose)
53
Aerotolerance test
- Growth on SBA plate incubated aerobically in ambient air
- Growth on CHOC plate incubated anaerobically in CO2
- No growth on CDC BPA incubated anaerobically
Obligate aerobe
54
Aerotolerance test
- No growth on SBA plate incubated aerobically in ambient air
- Growth on CHOC plate incubated anaerobically in CO2
- No growth on CDC BPA incubated anaerobically
Capnophilic aerobe
55
Aerotolerance test
- Growth on SBA plate incubated aerobically in ambient air
- Growth on CHOC plate incubated anaerobically in CO2
- Growth on CDC BPA incubated anaerobically
Facultative anaerobe
56
Aerotolerance test
- No growth on SBA plate incubated aerobically in ambient air
- No growth on CHOC plate incubated anaerobically in CO2
- Growth on CDC BPA incubated anaerobically
Obligate anaerobe
57
Which form of GLC is most commonly used, volatile vs. non-volatile
Volatile
58
3 tests for proteolysis
- Gelatin hydrolysis
- Milk liquefaction
- Meat digestion
59
Gelatin hydrolysis
- Positive appearance
- Negative appearance
- Pos: liquid
| - Neg: solid
60
Milk liquefaction
- Positive appearance
- Negative appearance
- Pos: curds or curdling/digestion
| - Neg: no change
61
Meat digestion
- Positive appearance
- Negative appearance
- Strong pos: no individual particles
- Weak pos: some individual particles
- Neg: undigested particles
62
What media is used to anaerobic identification of biochemicals?
Egg yolk agar (EYA)
63
What reactions take place on EYA?
- Lecithinase
- Lipase
- Proteolysis
64
Lipase
| - Positive test
- Pos: oil on water appearance
65
Lecithinase
| - Positive test
- Pos: opaque appearance around colonies
66
Catalase
- Positive test
- Negative test
- Pos: bubbles
| - Neg: no bubbles
67
Indole
- Positive test
- Negative test
- Pos: red
| - Neg: no color change
68
Spot indole
- Positive test
- Negative test
- Pos: color change (blue/purple)
| - Neg: no color change
69
Esculin
- Positive test
- Negative test
- Pos: black
| - Neg: no color change
70
Growth in presence of bile (20%)
- Positive test
- Negative test
- Growth: orange and turbid
- Stimulated growth: opaque yellow
- No growth: no change
71
Urease
- Positive test
- Negative test
- Pos: pink
| - Neg: yellow
72
2 newer technologies for identification of anaerobes
- 16S rRNA
| - MALDI-TOF
