5-Anaerobes (2)

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

• p

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

○

Food: especially spores in home canned vegies

○

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