Anaerobic Procedures :)

Question 1

Facultative anaerobes grow in what kind of environment?

Answer 1

aerobically and anaerobically

Question 2

obligate anaerobes can only grow in ______ environment. ________ is toxic to them. What does it mean if they’re a strict obligate anaerobe?

Answer 2

only anaerobic; oxygen is toxic

if strict obligate, they cannot tolerate more than 0.5% oxygen

Question 3

what are moderate obligate anaerobes and aerotolerant anaerobes?

Answer 3

moderate: can tolerate 2-8% oxygen

aerotolerant grow poorly in ambient air (21% oxygen)

Question 4

what does it mean that anaerobic bacteria require a low redox potential? Does human tissue have high or low redox potentials?

Answer 4

LRP means the environment is more anaerobic than aerobic; most human tissue have high redox potential (aerobic environment)

Question 5

what are three reducing agents frequently included in anaerobic media?

Answer 5

1. thioglycollate
2. cysteine
3. dithiothreitol

Question 6

what are the common body sites that anaerobic bacteria like to colonize, and how is this possible?

Answer 6

oral cavity, URT, intestinal tract, genitourinary tract, and skin due to facultative organisms use up the oxygen in the protected areas

Question 7

what are the two disease types for anaerobic bacteria, and which is more common to cause infections?

Answer 7

exogenous – from outside the body (eg due to spores)

endogenous – due to host normal flora that it cannot keep in their normal habitat
- more common infections than exogenous

Question 8

2/3 of human infections are caused by what 6 organisms?

Answer 8

B. fragilis, pigmented Prevotella spp., Porphyromonas spp, Fusibacterium nucleatum, C. perfringens, and anaerobic cocci

Question 9

what are some appropriate anaerobic specimens?

Answer 9

abcess aspirates, tissue/biopsy material, special aerobic swabs, protected bronchitis brushes, suprapubic urine aspirate, and blood/normally sterile body fluids

Question 10

what is a major inappropriate specimen for anaerobic cultures?

Answer 10

swabs due to only holding a little of material and their likelihood of exposure to oxygen

Question 11

what is a PRAS medium? what three things does it consist of?

Answer 11

prereduced, anaerobically sterilized

consists of:
1. agar transport media
2. rezasurin: oxygen indicator
3. reducing substances

Question 12

what kind of loops and needles are not appropriate to use for anaerobic bacteria?

Answer 12

nichrome

Question 13

what some examples of anaerobic blood agar plates (anaBAP)?

Answer 13

CDC anaBAP, Brucella BAP, enriched BHI, and Schaedler blood agar

Question 14

what does the BBE agar have in it that makes it selective and differential for B. fragilis?

Answer 14

Gentamicin: antimicrobial agent
Bile: most anaerobes are inhibited by bile
Esculin: hydrolysis of esculin
- B. fragilis
- Bilophila wadsworthia
- some Fusobacterium spp.

Question 15

what is the CCFA agar selective and differential for? What do pos and neg results look like

Answer 15

Clostridium difficile
- cycloserine and cefoxitin are antimicrobials that inhibit many organisms
- neg: still pink media
- pos: media turns yellow with ground glass colonies

Question 16

KVLB agar will grow what two organisms?

Answer 16

Bacteroides spp. and Prevotella spp.

Question 17

what is a catalyst that will remove oxygen to create an anaerobic environment? What are two indicators, and what colors are they when there is oxygen present

Answer 17

palladium (turns hydrogen and oxygen to make water)

indicators:
1. methylene blue: blue
2. rezasurin: pink

Question 18

what is the principle of anaerobic tolerance and how to perform?

Answer 18

streak for growth on BAP (or choc) and also on anaBAP (eg Brucella plate). Incubate both and compare if there is something growing on the anaerobic plate that isn’t on the aerobic one

Question 19

conventional biochemical tube tests what kind of tubes containing what kind of medium supplied with glucose/nitrate/urea?

Answer 19

Thio or peptone yeast medium

Question 20

what system uses substrate tests to detect enzymes in an organism? what uses panels of wells containing biochemical reactions for ID?

Answer 20

rapid enzymatic systems

micro biochemical test tube

Question 21

what are the most commonly disks for anaerobic tests? what id the diameter to consider a resistant or susceptible result?

Answer 21

vancomycin, colistin, and kanamycin

inhibition of 10 mm or more = susceptible

10 mm or less is considered resistant

Question 22

what test is used to ID gram positive cocci, and what do resistant and susceptible results look like?

Answer 22

sodium polyanethol sulfonate (SPS)

12 mm or more = susceptible
12 mm or less = resistant

Question 23

bile tolerance is used to see if an organism can grow in ____% bile

Answer 23

20

Question 24

what measures and measures metabolic end products and cellular fatty acids?

Answer 24

gas-liquid chromatography

Question 25

lecithinase degrades _______ to form insoluble _________ by inoculating the test organism onto an ___ ____ ____. What spp is this test used to ID?

Answer 25

degrades lecithin to form insoluble diglycerides onto an egg yolk agar
- pos result: white opaque zone on agar
- used to ID Clostridium spp.

Question 26

what test degrades glycerol into free fatty acids? What does a pos result look like?

Answer 26

lipase
- pos: pearly sheen on egg yolk agar

Question 27

a series of quadrant plates are known as ________?

Answer 27

presumpto plates

Question 28

what organism is identified by the reverse CAMP test, and how to do the test?

Answer 28

C. perfringens toxin works with the beta-hemolysis of GBS
- streak down a line of GBS and perpendicular but not touching it, streak a line of suspected C. perfingens, Arrow of hemolysis is pos result

Question 29

stool/rectal swabs are only acceptable specimens if you’re looking for what organism?

Answer 29

C. difficile