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Micro/Immuno Part 2 > Anaerobic Bacteria > Flashcards

Flashcards in Anaerobic Bacteria Deck (19):
1

Anaerobic Bacteria

-obligate anaerobes
-can be aerotolerant of facultative
-use other flashcards about fermentation pathways-inefficient, intermediate waste product,leave energy in final, waste is organic acid or alcohol, repertoires

2

common sources of pathogen 1

-normal flora escape normal compartment
-actinomyces, B corrodens, P melaninogenica in mouth
-B fragilis in colon and vagina
-abcess fills with bacteria and dead neutrophils, swells, becomes painful

3

common source of pathogens 2

-soil-spores enter through wounds, germinate, produce exotoxins
-C tetani
-C perfringens
-C botulinum

4

Route of entry 2 from soil

-spores germinate in vacuum packed foods
-C perfringens in food poisoning:bacteria briefly survive in gut and release enterotoxin
-C botulinum in infants-bacteria survive briefly in gut and release neurotoxin
-Botulism in foodborne-bacteria do not survive in gut but already filled food with neurotoxin

5

anaerobes in lab

1. sample must be handles anaerobically and labeled as such
2. standard clinical labs are anaerobic culture, gram stain, gas chromatography

6

liquid culture

-innoculate test tube of media
-add a reducing agent like thoglycolate to eliminate dissolved oxygen
-fill completely, stopper tightly and incubate WITHOUT SHAKING
-aerobe grows on top, anaerobe on bottom, both in middle

7

agar plates

-quickly streak onto agar media with usual benchtop sterile technique
-place plates in anaerobic culture jar
-add a chemical system to remove oxygen from jar's atmosphere and color indicate successful removal (Gas-Pak)
-airtight seal
-place whole jar in incubator for 48 hours
-note that colonies will die very shortly after removal from jar unless using a glovebox

8

glovebox

-box with oxygen free atm
-airlock for bringing plates and instruments in and out (flood with nitrogen)
-gloves attached to box for manipulations within

9

Identifying anaerobes

-gram stain
-chemical testing-ability to ferment, hydrolize various macromolecules
-gas chromatography

10

gas chromatography

-analyzes organic acids being produced by the anaerobes fermentation pathways
-extracts from culture or pus sample are run against control mixes

11

treatment of anaerobic infections

-surgical care for abscess
-antitoxin for toxigenic disease-tetanus/botulism
-antibiotics-penicillin G, cefotoxin, chloramphenicol, clindamycin
-metronidazole-specific for anaerobic bacteria-broken down to active form where the bacteria are

12

clostridium

-clostridium all gram pos and rods and in soil, except C dif
-spores to survive transfer
-all make exotoxins

13

GNAB

-gram neg anaerobic bacilli-normal flora gone bad
-bacteriodes and prevotella
-rods
-no spores

14

actinomyces

-gram pos
-long rod
-no spores

15

C. tetani

-spores are environmental: soil, dust, manure, some human skin and GI
-gram pos
-spore-forming
-transmitted to humans by soil contamination of wounds-splinters, thorns, punctures, IV septic surgery, septic handling of umbilical cord
-insertion beneath the skin surface limits air contact
-spores germinate- vegetative cells release exotoxin tetanospasmin
-large and small subunit, small unit delivered, retrograde axonal transport to CNS
-acts as protease, cleaves synaptobrevin in inhibitory motor nerves of CNS, no inhibitory motor neuron activity
-can't stop contracting

16

generalized tetanus

-bacteria from locus of infection
-exotoxin tetanospasmin enters bloodstream
-morbidity
->50% untreated mortality from resp failure
-21-31% treated mortality
-vaccination can save

17

C dif

-gram pos spore forming rod
-pseudomembranous colitis
-disrupts normal flora
-normal gut flora for 3% general pop, 30% hospitalized
-fecal oral, especially nosocomial from spores on hospital instruments or on hands of HCWs

18

c dif pathogenesis

-recent course of antibiotics or cancer chemotherapeutics supresses other normal flora
-germinating cells release exotoxin A, disrupts tight junctions, causing swelling and IF
-exotoxin B is major toxin, disrupts cytoskeleton by depolymerizing actin, kills surrounding cells
-more virulent and drug resistant in 2001-2002
-mortality increased from 6%

19

c dif diagnosis and treatment

-sigmoidoscopy
-patches of dead and dying cells appear as yellow white plaques
-withdraw initial antibiotic cures 20%
-oral metronidazole or vancomycin
-surgical resection or removal of the colon may be required
-toxic megacolon or colonic perforation may occur