Anaerobic Bacteriology Introduction Flashcards
Objective 1: Define the following terms: anaerobe
Anaerobe: a bacterium that is able to replicate without oxygen
Objective 1: Define the following terms: polymicrobial
Polymicrobial: refers to multiple isolates of bacteria
Objective 1: Define the following terms: pleomorphic
Pleomorphic: an bacterium that displays many gram stain morphologies (shapes and forms)
Objective 2: **Differentiate between the following:
- Obligate aerobe
- Example
- Microorganism that requires oxygen for growth
- Pseudomonas spp., Micrococcus spp.
Objective 2: **Differentiate between the following:
- Microaerophile
- Example
- Microorganism that grows in conditions of reduced oxygen and increased carbon dioxide
- Campylobacter spp.
Objective 2: **Differentiate between the following:
- Facultative anaerobe
- Example
- Microorganism that does not require oxygen for growth, but will use oxygen and grow better if present
- E. coli, S. aureus
Objective 2: **Differentiate between the following:
- Aerotolerant anaerobe
- Example
- Microorganism that grows best in the absence of oxygen, but can tolerate low concentrations of oxygen
- Propionibacterium, C. tertium, C. carnis, C. histolyticum
**Differentiate between the following:
- Strict obligate anaerobe
- Example
- Microorganism that can only live and reproduce in a anaerobic environment
- C. novyi, C. haemolyticum
Objective 3: Recognize in which categories most aerobes and anaerobes fit
- Aerobes: Facultative anaerobes
- Anaerobes: Aerotolerant anaerobes
Objective 4: **Identify the sites where anaerobes are found as normal flora
- Nose
- Mouth
- Oropharynx
- Skin
- GI
- GU/Vaginal
Objective 5: Differentiate between endogenous and exogenous infections in relationship to
anaerobes
Endogenous: the result of anaerobes that are normal flora of the body
Exogenous: the result of anaerobes that are located outside of the body
Objective 6: **Recognize which source of anaerobes (exogenous or endogenous) is most common
in anaerobic infections
Endogenous
Objective 7: Discuss the reason(s) that most anaerobic infections are polymicrobial
Lowers the redox potential of the environment creating a suitable environment for anaerobic growth
Objective 8: Recognize the types of infections routinely caused by anaerobes
- Dental infections
- Intra-abdominal/Pelvic abscess
- Brain abscess
- Lung abscess
- Bacteremia
Objective 9: List factors that predispose a person to anaerobic infection and signs of an anaerobic infection
- Vascular stasis
- Tooth extraction/oral surgery
- GI tract surgery/traumatic puncture of bowel
- Infection close to site containing normal flora
- Necrotic tissue
- Foul odor
Objective 10: **Recognize the types of clinical specimens that are acceptable for anaerobic culture
and those not acceptable for culture
Acceptable:
- Needle aspirates
- Tissue or bone
- Sterile body fluids (except urine)
Not acceptable:
- Upper respiratory specimens
- Surface wounds
- Stool (except C. diff)
Objective 11: Describe why aspirated specimens are preferred over specimens submitted on swabs
Swabs collect less material and likely to possess contaminated flora
Objective 12: Discuss why the source (site) from which the specimen was collected affects its acceptability
Most anaerobic infections are endogenous – must differentiate if the organism is part of the infectious process and not normal flora
Objective 15: Discuss the 3 supplemental requirements for anaerobic media and the storage
conditions necessary for maintaining anaerobic media
- Vitamin K
- Hemin
- Yeast extract
Stored at room temperature
Pre-reduced (ensures redox potential stays low)
Objective 16: **List the factor that has the largest impact on the oxidation-reduction potential of
anaerobic media.
pH
Objective 17: List 5 reducing agents that can be added to media to maintain an anaerobic environment
- Enriched thioglycollate (THIO)
- Chopped meat
- Serum
- Cysteine
- Rumen Fluid
Objective 18: Define the term PRAS
Pre-Reduced Anaerobically Sterilized
Objective 19: **Discuss the purpose of the various plating media presented in lecture (ABAP, PEA,
KV/PV, LKV, BBE).
ABAP (Anaerobic Blood Plate Agar)
- non-selective (anything that will grow in an anaerobic
environment will grow on this plate)
PEA
- selective from a mixed culture
- selective for anaerobes
- inhibits facultative anaerobic GNRs
- inhibits Proteus swarming
KV/PV/LKV (antibiotics w/ laked blood)
- selective for Gram negative anaerobes
BBE (Bacteroides Bile Esculin)
- selective for Bacteroides spp. (bile)
- differential for esculin hydrolysis (media turns black)
Objective 20: Describe 3 anaerobic systems used in clinical laboratories
- Anaerobic chambers
- Anaerobic jars
- Anaerobic bags and pouches
Objective 21: **Differentiate between ambient air, CO2, microaerophilic and anaerobic incubation
conditions (% of O2 and % of CO2)
Ambient air: 21 O2, 0.03 CO2
CO2: 15-21 O2, 5-10 CO2
Microaerophilic: 5 O2, 10 CO2
Anaerobic: 0 O2, 5-10 CO2
Objective 22: List the 4 requirements of an anaerobe chamber
- Catalyst
- Desiccant
- Anaerobic gas (5 H2, 5-10 CO2, 85-90 N2)
- Redox indicator
Objective 23: Recognize the typical catalyst used in an anaerobe chamber
Palladium coated aluminum pellets
Objective 24: Identify a desiccant used in anaerobe chambers
Silica gel
Objective 25: Recognize the typical gas mixture in an anaerobe chamber
5 H2, 5-10 CO2, 85-90 N2
Objective 26: List 2 oxidation reduction indicators used in anaerobe chambers.
- Methylene blue
- Resazurin
Objective 28: List the major advantages and disadvantages of anaerobe chambers, anaerobe jars,
and anaerobe bags/pouches
Anaerobe chambers
Advantage:
- Specimens never exposed to oxygen during set up
- Plates can be screened as often as desired
- Large volume cultures
Disadvantage:
- Cumbersome
- Airlock
- Space
Anaerobe jars
Disadvantage:
- Plates must be removed to screen
Anaerobe bags/pouches
Advantage:
- Transport, esp. when delay is expected
Objective 30: Recognize the importance of incubating anaerobe plates and biochemicals for 48 hours
Anaerobes are susceptible in the first 48 hours of growth – may inhibit growth or kill some organisms
Objective 32: Recognize the form of Gas Liquid Chromatography most commonly used (volatile vs.
non-volatile).
Volatile
Objective 33: Identify 3 tests for proteolysis
- Gelatin hydrolysis
- Milk liquefaction
- Meat digestion
