Week 11 - Anaerobes Flashcards
What do aerobic and faculatative anerobes have to protect them from superoxide anions and their toxic derivatives
superoxide dimutase and/or catalase where are anaerobes have neither
where are anerobes found
-environment soil and water
-NF - places where oxygen exposure is minimal most in like GI tract, genital tract or skin
-when other facultative orgs are in the same environment it helps to reduce O2 availability
What are the characteristics of a anerobic infection
-polymicrobic where both aerobes and anaerobes work together to cause disease
-smells bad
- necrotic tissue blocks blood flow and allows the anaerobes to grow
-caused by both endogenous and exogenous bacteria
Obligate and strict = dies upon O2 exposure
aerotolerant - what we use in the labs for testing **
Clostridium novei - control org for ana gas pak
What are endogenous infections
-grow from own flora = GI tract, gingival crevices around teeth , skin and glands
-the infection will occur close to where the bacteria is found = deep wound infection occurring after surgery or septicemia after dental work
-reduced blood flow = reduced oxygen tension perfect anerobe growing conditions
-ABotic treatment for aerobes can also allow anaerobe growth
What are exogenous infections
-from environment = soil
- caused by spore bearers Clostridia = contamination of trauma or puncture wound
tentanus , animal bites, septic abortion and gangrene
What are some predisposed conditions that can cause anaerobe associated infections
-bites
-vomit in lungs
-oral cavity puncture - dental
-GI tract puncture
how will we know an infection in close to the mucosal surface or area of NF
-odor
-large amount of gas (gas gangrene due to clostridium)
-black color or red fluorescence
-sulfur granules
-gram will show PMN leukocytes but if you dont see them that okay too because C perfringens produce enzymes that destroy neutrophils and macrophages
What is clostridium ?
found?
Anaerobic Gram Positive Bacilli
-large GPB
-pathogenic due to exotoxins
-produces spores -terminal (swelling in the end) and subterminal (swelling in middle)
found in
-soil, dust, water
-GI tract and genital tract
Clostridium tentani
ANA GPB
found :
-soil, manure
-spores can survive many years
-not invasive and must be inoculated aka puncture wound
-produces exotoxin at site which spreads through the body
-the exotoxin is the one that causes the symptoms its a neurotoxin not the bacteria
C . tetani – Clinical Significance
- convulsive muscle contractions
-head and legs back = risus sardonicus with lock jaw
-death from resp failure
C. tetani: Laboratory Diagnosis
- grows on BA anaerobic conditions as fine film over the agar and looks like its not inoculated
-spready and thin
-motile
-detect with biochem kits, molecular or GLC
box car GBP= round terminal spores = drumstick
Clostridium tetani
prevention and treatment
prevention
-tetanus TOXID vaccine containing inactivated tetanus toxin stimulating the body to make AB to toxin
-ARTIFICIAL ACTIVE LONG LASTING
Treatment
-antitoxin injection = pre formed AB to neutralized the toxin
ARTIFICAL PASSIVE SHORT
Clostridium botulinum
Clinical Significance:
-food intoxication
-poorly canned foods or stored food - toxin is produced - baby food, bar clams
-meat fish, beans
-acidic foods will not support growth
-infant instances after ingesting honey with spores = hypotonia no muscles
-in botox
-flaccid paralysis - relives muscle opposite to c tetani
most lethal bacterial poison known
-odorless, tasteless
-attacks CNS causing paralysis
-affects respiratory muscles like heart - cardiac arrest
-destroyed by heat - after boiling 15 mins
-possible bioterrorism
-three types of effects : food borne, wound and infant botulism
Laboratory Diagnosis and treatment
Clostridium botulinum
-oval subterminal spores
-motile
-GLC
-in Ba ANA large grey irregular, grainy and filamentous border
treat
Botulinum antitoxin neutralizes the toxin
Clostridium perfringens
Clinical Significance:
-found in soil
-readily contaminates wounds and food
-produces exotoxin that causes the death of local tissue producing alpha and beta toxin = double zone
-food intoxication and mild necrosis (gas gangrene)
-production of gangrene - bubble because muscle sugars start fermenting under the skin
-if there is food poisoning its mild and self resolving
-not invasive its the toxin and necrosis . once the bacteria in the area and system is cleared the infection leaves too
-infection cant jump from one area to the next
Clostridial myonecrosis caused by
Clostridium perfringens
especially in those with restricted blood flow to limbs like diabetics
-needs debridement in the area if not cleaned then you need to amputate
-better prognosis if the infection is away from organs aka lower extremities
-toxins dont get far unless its gotten into the blood stream
Actinomyces
significance
-actis = ray beam and mykes = mucus
-relationship with long term IUD users
-causing draining sinuses with ppt yellow colonies = sulphur granules surrounded by PMNs which you crush and gram
-occurs from tooth abscess or extraction where the endogenous infection causes a suppurative infection - actinomycosis
-lumpy jaw - secondary to trauma or dental procedure
-abcesses are not kept at the jaw they can spread to the abdomen and thoracic area
-treatment with penicillin after lesions are drained
-can travel to areas nearby causing neck abcess
Actinomyces
lab diagnosis
-short branching GPB- rod
-NF in mouth and intestinal tract
-lab must be told specifically to culture
-like a starburst
-colonies look like molar tooth and are slow growing
-culture for 7 days
Laboratory Diagnosis
Clostridium difficile
-isolated from stool
-large flat colonies
-barnyard odor
-chartreuse fluorescence
-Toxin in stool is most important
-ELISA - similar to pregnancy test look for the AG on the org and the tox (need two tests to detect pathogenic clostridium because it can be NF)
-if pos for AG and neg for TOX = org is not the problem
- if pos for both AG and TOX then it the issue
-PCR also done
-Gram = thin large GPB spore forming
-anaerobe
-no hemolysis
Treatment
-Vanc or Metronidazole (treat anaerobes)
Lab Diagnosis
Clostridium perfringens
-target
-lots of spore
-anaerobe
-double zone inner due to 0 (theta) toxin and outer due to alpha toxin
-non motile
-reverse CAMP positive - this is the differentiating test from other Clostridium
-GLC
-BOX CAR LOOK
- semi opaque , shiny
-lecithinase pos on egg yolk agar
Clostridium difficile
-can occur after using broad spectrum AB as it kills all NF in the bowel allowing pseudomembranous colitis to grow
-cytotoxin overgrowth produces the strain C diff
-causes severe diarrhea and tissue
necrosis
-nocosomial
-infection in large intestine
-high mortality
Propionibacterium
found
gram?
-called cutibacterium
NF on skin
-most common ANA now called Cutibacterium acnes
-contaminant in cultures or spinal fluids
-causes acne
-causes brain abscess
Gram: Pleomorphic GPB - curved; coryneform bacilli
-on direct sample there will a variation - cocci or bacilli
On anaerobic BA: small opaque, white, circular
Cat + (we dont do catalase on anaerobes because they need air but if you do you need to leave it for 10-15 mins before you do the test need to expose to air and has the catalase enzyme),
-indole POSITIVE (P.acnes)
Bacteroides fragilis group
significance
anaerobe
-NF in oral cavity, GI tract , found in poop
-most common genus that causes human infection
-can be mixed with other infections
-intra-abdominal and pelvic abscess, liver abscess, brain abscess
Laboratory Diagnosis
Bacteroides fragilis group
-Small GNB or GNCB with rounded ends; look vacuolated - not spores the bubble at the end is a vacule
-Anaerobic
-pleomorphic
-grows in presence of 20% bile any inhibition is sensitive**
-hydrolyses esculin **
-catalase positive
-grows on kanamycin-Vancomycin-laked blood selective agar
-turns BBE medium brown to black - diff from enterococci
resistant to Kanamycin and Vancomycin
shiny or dull, brown black entire edge only young colonies will fluoresce under woods
