Anaerobe Lecture pt 1 Flashcards
How much oxygen is in each kind of air/system for the following?
- ambient air
- CO2 incubator
- microaerophilic system
- anaerobic system
- ambient air: 21%
- CO2 incubator: 15%
- microaerophilic system: 5%
- anaerobic system: 0%
what is a strict or obligate aerobe?
like oxygen and use O2 as a terminal electron acceptor during metabolism (metabolism during respiration)
how do facultative anaerobes grow in the presence and absence of oxygen?
presence: grow using aerobic respiration
absence: fermentation
what are aerotolerant anaerobes?
grow poorly in ambient air (21% oxygen) and better in anaerobic conditions
use fermentation for energy and growth
microaerophilic organisms are capable of growing in what percentage of oxygen? What are two examples of microaerophilic organisms?
5%
- H. pylori and Campy spp.
moderately obligate anaerobes tolerate oxygen at what percentages? What are two examples?
2-8%
- Bacteroides and many Clostridium spp.
strict obligate anaerobes cannot tolerate more than what percent of oxygen?
0.5%
normal human tissue has a high or low redox potential? What is meant by this?
high
it mean that they have a high amount of oxygen reactions happening, which don’t make for hospitable anaerobe environments
infected human tissue have what kind of redox potential that make them a good environment for anaerobes?
low redox potential
what are three common reducing agents in anaerobic media?
- thioglycolate
- cysteine
- dithiothreitol
in the colon, anaerobic bacteria outnumber enterobacterales in what ratio?
1000 to 1
what are four popular anaerobic habitats?
water, soil, some animals, and humans (URT, GI / intestinal tracts, and oral cavity)
what are manifestations of anaerobe infections?
- necrotic tissue
- foul-smelling discharge
- gaseous discharge
- black exudate
- sulfur granules
what are acceptable specimens for anaerobes?
tissue/biopsy material, aspirates, normally sterile body fluids
what color is the oxygen indicator Resazurin when anaerobic and aerobic conditions?
what about methylene blue when exposed to O2?
Resazurin:
anaerobic: colorless
aerobic: pink
Methylene blue: blue when exposed to oxygen
what kind of loops can you not use when processing specimens for anaerobic growth?
nichrome loops because they oxidize the inoculum and culture media
what does PRAS stand for?
pre-reduced anaerobically sterilized
what is the one type of nonselective anaerobic media and the types of this media?
anaerobic blood agar (anaBAP)
- CDC anaerobic blood
- brucella blood
- enriched BHI
- Schaedlers
what is an anaPEA and CCFA and their functions as anaerobic media?
anaerobic phenylethyl alcoholic blood agar:
- inhibits enterobacterales
- supports GPC and anaerobes
Cycloserine-cefoxitin fructose agar
- selective, differential, and inhibitory
- used for specifically C. diff
what is a BBE agar?
bacteroides bile esculin agar
- selective and differential
- isolates and presumptive ID of B. fragilis spp.
what three things does the BBE agar contain?
gentamicin (an antibiotic), bile, and esculin
KVLB agars are both ______ and ______. What two spp will grow on it?
Kanamycin-vancomycin laked blood agar
- selective and inhibitory
- growth for specifically Bacteroides and Prevotella spp.
what is the anaerobic broth used in the micro lab? What must be done to it prior to use?
Thioglycollate (thio) broth must be boiled (reduced) before usage
what are the kinds of gas used to incubate anaerobes?
nitrogen (inactive), hydrogen (active), and carbon dioxide (for capnophiles like Campy)
what is the catalyst in anaerobic jars?
palladium
what is the aerotolerance test?
to see if a colony is facultative or strict anaerobe:
- incubate colony on both chocolate (grow in aerobically) and anaBAP (grow anaerobically)
