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Anaerobes
Bacteria that do not require oxygen for growth & reproduction Oxygen is detrimental to them
Obligate
strict) anaerobe = tolerates no more than 0.5% oxygen
Aerotolerant
(moderate) anaerobe = tolerates small amounts (2-5%) oxygen
Facultative anaerobes
Bacteria that can grow in the presence or absence of oxygen
What are the signs that a patient has an anaerobic infection
Foul-smelling
Gas bubbles
Black Blood
human/animal bite or abdominal surgery
Sulfur granules
What are acceptable specimen for anaerobes
Sterile body sites
blood, bone marrow, deep wounds, CSF, other body fluids/ deep tissue
Aspirates specimens= Suprapubic (urine), Culdocentesis ( uterus), Transtracheal ( lung)
What are unacceptable specimens for anaerobes
Contaminated body sites
Ex- Specimens for routine culture superficial wounds/sores/ulcers swabs mouth/throat/sputum specimens stool/rectal swab (unless for C. difficile) vaginal/cervical/urethral swabs clean catch/catheterized urine
What is the best specimen
needle aspirate
Anaerobic chambers
best; anaerobes never exposed to air; expensive
Anaerobic jars
Gas pak or evacuation/gas replacement---less expensive; anaerobes exposed to air
Anaerobic bags
least expensive; accommodates one or two plates, but anaerobes exposed to air
What are the components of the Gas Pak system
Plastic jar, lid with rubber seal, gas generating envelope, palladium catalysts
What are the signs that the gas pak is working
lid feel warm
moisture on the side of the jar
Methylene blue indicator loses its blue color and turns white
( Resazurin indicator may be used; it turns from white to pink in absence of oxygen
What are the signs that the gas pak is not working
Lid crack
Rubber seal is broken
Catalyst not working
Gas generating envelop defective
ANA- BAP ( CDC- ANA/ BRU- ANA)
Components = SBA + hemin/ Vit. K
Purpose = nonselective/ most anaerobes grow well on
Draw back = Facultative anaerobes also grow well on it
BBE= Bacteroides Bile Esculin
Components = 20% bile and Esculin
Purpose = Select and differentiate the B. fragilis group
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KVLB = Kanamycin Vancomycin, Laked Blood
Components = laked SBA and antibiotics
Purpose = enhance pigment of Prevotella / Recovers B. frag group
PEA = Phenylethyl-alcohol
Components = SBA + PEA
Purpose = Inhibit gram negative facultatives, select for gram positive anaerobes, inhibits swarming proteus
CNA = Colistin Naladixic Acid
Components = SBA + antibiotics
Purpose = same as PEA
Many labs use PEA for anaerobes and CNA for aerobic culture
Liquid Media = Enriched Thio
Components = broth / hemin and vitamin k
Purpose = holding broth
Look over slide 32
EYA = Egg Yolk Agar
Components = egg yolks, provide fatty acids
Purpose = detect lipase/ lecithinase production
Lipase positive =iridescent sheen 0r pearly layer
Lecithinase positive opaque precipitate under the colony
Used to ID Clostridium species
CCFA = Cycloserine Cefoxitin Fructose Agar
Components= Antibiotics, furctose, indicator
Purpose= select for Clostridiodes difficlile
horse stable odor yellow colonies (fructose-positive
What is a Catalase test
3% or 15% (best) H202
What is the reaction of a positives catalase
bubbles
What is a negative reaction of catalase
no bubbles
What is spot Indole test
reagent: para-dimethyl cinnamaldehyde
What is a positives reaction of indole
blue-green color
What is a negative reaction of indole
pink color
What are differentiation disks use for
Used to determine if the anaerobe is
sensitive or resistant to antibiotics, such as
Kanamycin (k), Vancomycin (Va), Colistin
(Cl)
Sensitive
zone of inhibition ( no growth)
Resistant
no zone of inhibition (growth)
Clostridium tetani
small gram positive bacilli with round, terminal spores , resemble a tennis racket or drum stick
Propionibacterium
pleomorphic gram positive bacilli; beaded, clubbed, palisades, diphtheroidal
Fusobacterium nucleatum
pale staining gnb with tapered ends
Fusobacterium necrophorum
pale staining gram negative bacilli with rounded ends, may be pleomorphic with coccoid bodies and chains
Peptostreptococcus
gram positive cocci, single, pairs &chains
Veillonella
Tiny, gram negative cocci, pairs and packets
Where are polymicrobic abscesses founded in
dental,thoracic or abdominal surgery, or in tissue abscesses
What are the body sites for Endogenous anaerobes
mouth ,GI tract ,genital ,skin
Endogenous
Human normal (indigenous) flora aka inside the body
What cause lumpy jar
Actinomyces israelii
What cause endogenous infections
Veillonella
Peptostreptococcus
Prevotella & Porphyromonas
Fusobacterium
Bacteroides species
Exogenous
live outside the body ( soil, animals, water and plants)
Exogenous infection are cause by what
The clostridium species
Clostridium botulinum
Wound: trauma to skin
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Food: especially spores in home canned vegies
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Infant: especially spores in honey
Bacteria grow and produce the most potent neurotoxin known that inhibits the release of acetylcholins, causing a flaccid paralysis
Clostridium tetani
causes lockjaw ( tetanus)
Bacteria in the wound produce a potent neurotoxin, tetanospasmin that causes continuous muscle spasms
Gram positive bacilli with round terminalspores (“tennis racket” appearance)
What anaerobes is endogenous and exogenous
Clostridium perfringens, Clostridiodes difficille
What are the three most commonly isolated anaerobes
Bacteroides fragilis group
Clostridium perfringens
Peptostreptococcus species
What anaerobes are Gram positives
Clostridium
Propionibacterium
Peptostreptococcus
What anaerobes are gram negative
Fusobacterium
Veillonella
Clostridium perfringens
wound infections - most common cause of gas gangrene (myonecrosis) in the US
Pathology caused by
enterotoxins (food poisoning)
exotoxins & enzymes (gas gangrene)
Large, gram positive bacilli
Box cars”: rectangle with square ends
What cause a clostridiodes difficille infection
Infections caused by toxins A and/or B
What are Clostridiodes difficile majors infection
(Colitis PMC) and (diarrhea AAD)
Clostridiodes difficile
gram positive bacilli
subterminal spores
Bacteroides fragilis are resistant to what
Kanamycin, Vancomycin, Colistin
What Prevotella melanogenicus/oralis look like on a gram stain
small gram negative bacilli/coccobacilli; some pleomorphism