Anaerobic bacteriology Flashcards
Concepts in Anaerobic Bacteriology
Normal Air = about ___% O2 and ____% CO2
CO2 Incubator = about _____% O2 and ___%- ___% CO2
Microaerophilic System = ___% CO2
Anaerobic System – __% O2
21; 0.03
15; 5-10
5
0
Obligate anaerobes
-they undergo no ___________
-they can do _____
-are killed by ____
lack certain enzymes such as :
____
_____
____
oxidative phosphorylation
fermentation; oxygen
superoxide dismutase
catalase
peroxidase
Obligate anaerobes grow ONLY in the absence of _______ but vary in their _______ and can be classified as _____ anaerobes or ______ anaerobes
molecular oxygen
sensitivity to oxygen
moderate; strict
Moderate anaerobes can ________ exposure to air for _______ but cannot _______
Tolerate ; several hours; multiply
multiply
Strict anaerobes are _____ by only a _______’ exposure to air
killed; few minutes
Fortunately ____ anaerobes are seldom associated with human infections
strict
Anaerobes
Bacteria that require anaerobic conditions to _____ and ______
initiate and sustain growth
Strict (obligate) anaerobe
Unable to grow if there is > than ____% oxygen
0.5
Moderate anaerobes
Capable of growing between ____% oxygen
2-8
Microaerophillic bacteria doesn’t grow in air
T/F
F
It just Grows poorly in air, but better in anaerobic conditions
Facultative bacteria (facultative anaerobes)
Grows only in the presence of air
T/F
F
both in presence and absence
Anaerobes do not have enzymes for __________________________________, so oxygen can have a _________ or even ________ effect on them
protection against the toxic effects of molecular oxygen
bacteriostatic; bactericidal
Anaerobes require environments with (low or high?) oxidation- reduction potential (redox), so they must live in areas where the redox potential is ( low or high?)
Low
Low
Anaerobes are thought to be the second earliest forms of life
T/F
F
Earliest
All life on earth was (aerobic or anaerobic?) for hundreds of millions of years
Anaerobic
Today anaerobes are found in soil, fresh and salt water, and in ______ of humans and animals
normal flora
Problems in identification of anaerobic infections
1)______ during sampling or transportation leads to no growth
2)identification takes _______ or longer therefore limiting usefulness
3) often derived from ______ , therefor sample contamination can confuse
air in sample
several days
normal flora
Anaerobes that live outside the body are called “ _________ anaerobes” (Example: ________ species)
Anaerobes that live inside the body are called “ _________ anaerobes”
exogenous ; Clostridium
endogenous
Most anaerobic infections are from ( endogenous or exogenous ?) sources
endogenous
Classification of Medically Important Anaerobes
Gram positive cocci
-___________________
Gram negative cocci
–______________
Peptostreptococcus
Veilonella
Classification of Medically Important Anaerobes
Gram positive bacilli
•__________________________________
•______________
•_____________
•___________
•__________
Clostridium perfringens, tetani, botulinum, difficile
Propionibacterium
Actinomyces; Lactobacillus; Mobiluncus
Classification of Medically Important Anaerobes
Gram negative bacilli
————-
—————
—————
——————
Bacteroides fragilis, thetaiotaomicron
Fusobacterium
Prevotella
Porphyromonas
Epidemiology
–Endogenous infections
•Indigenous microflora
Skin: _________, _________
Upper respiratory: __________
Mouth:_____,________
Intestines:_____,_____,________
Vagina: _________
Propionibacterium; Peptostreptococcus
Propionibacterium
Fusobacterium, Actinomyces
Clostridium, Bacteroides, Fusobacterium
Lactobacillus
Epidemiology
–Endogenous infections
•Profound modification of flora in pathophysiologic states such as:
______________(PPI, antacids)
__________(____)
_________
Antimicrobials and other medications
Surgery (blind loops)
Cancers
Epidemiology of anaerobes
–Endogenous infections
Exogenous infections
T
Indigenous microflora of the skin:
Prevalence in areas exposed to air explained by (1) ____________ (2) ______________ of the microhabitats
oxygen consumption by aerobes
low oxidation-reduction potential
Role of Anaerobes
Role in normal host physiology
– Prevent _________ and ______ by ____
– Contributes to _________
colonization & infection by pathogens
host physiology
Role of Anaerobes
Role in normal host physiology
•– Prevent colonization & infection by pathogens
Bacterial interference through _____,_____,_______
Also by Interference with _______
•– Contributes to host physiology
E.g _________ synthesizes ________ and __________________
elaboration of toxic metabolites, low pH, depletion of nutrients
adhesion
B. fragilis; vitamin K ; deconjugates bile acids
Anaerobic Anatomical Sites for Endogenous Anaerobes
anaerobes often cause infection in the urinary tract
T/F
F
Rarely
Anaerobic Anatomical Sites for Endogenous Anaerobes
–GU Tract – cervical and vaginal areas have ____% anaerobes
–GI Tract – Approximately 2/3’s of all bacteria are in the ____; only cultured anaerobically if ___________ is suspected
50
stool
Clostridium difficle
Indications of Anaerobic Infections
Usually _______ ( ____ -producing)
Close proximity to a _____ surface
Infection persists despite _________
purulent; pus
mucosal
antibiotic therapy
Indications of Anaerobic Infections
Presence of ____ odor
Presence of large quantities of _____ (______ or ______ sound when tissue is pushed)
Presence of ____ color or ____ fluorescence
foul
gas; bubbling or cracking
black; brick-red
Indications of Anaerobic Infections
Presence of “ ______ granules”
Distinct morphologic characteristics in ________ preparation
sulfur
gram-stained
Virulence factors
•Lipopolysaccharide - promotes _______, enhanced _________
•Polysaccharide capsule - correlated with _______ production
•Enzymes a. ______ b. ________ which can lead to development of _______ and _____ emboli
abscess formation; coagulation
abscess
Collagenase; Heparinase
thrombophlebitis & septic emboli.
Virulence factors
____ chained fatty acids a. Butyrate- seen in ________ b. succinic acid – reduces _____
Short
dental plaque
phagocytic killing
Virulence factors
•Attachment and adhesion
______ and _______
•Invasion
________ in host tissue (trauma, disease)
________ of the organism
Polysaccharide capsules and pili
Alteration; Aerotolerance
Virulence factors
•Establishment of infection
_________ (B. fragilis)
_________ (Clostridium)
Maintenance of ________ environment
•Tissue damage
___________
Polysaccharide capsule
Spore formation
reduced oxygen
Elaboration of toxins
Clinical features of anaerobic infections
The source of infecting micro-organism is the ____________ of host
________ of host’s tissues provide suitable conditions for development of __________ infections
_______ formation
________ formation
endogenous flora
Alterations; opportunist anaerobic
Abscess; Exotoxin
Anaerobic infections are generally polymicrobial
T/F
T
Specimens for Anaerobic Culture
Tissue – must be placed in _______ transport bag or vial
Blood – ________________________ bottles are collected for most blood culture requests
an oxygen-free
aerobic AND anaerobic
Typical Anaerobic Media
_______________ agar (BRU/BA)
__________________ agar (BBE)
________________________ agar (KVLB)
_____________ agar (PEA)
Anaerobic broth, such as ______,________, or ________ agar
Anaerobic blood
Bacteroides bile esculin
Kanamycin-vancomycin-laked blood
Phenylethyl alcohol
thioglycollate (THIO) , brain heart infusion or chopped meat
Anaerobic Incubation
•Anaerobic ________ (p. 581)
•Anaerobic jars
________________ generate _____ and ____ , which combines with ____
•Anaerobic ______ or _____
chambers
Gas-Pak envelopes
CO2 and H2; O2
bags or pouches
Warning!:
_____ is explosive; _____ catalyst MUST be used with the anaerobic jars
H2; palladium
All anaerobic incubation systems must have ____________ system in place
an oxygen indicator
Definitive Identification of Anaerobes
_______ and ________ biochemical test media
Biochemical-based and preexisting enzyme-based minisystems
______ chromatographic analysis of metabolic end products
_________ analysis by GLC
PRAS (Pre-reduced Anaerobic System) and non-PRAS
Gas-liquid
Cellular fatty acid
Frequently Encountered Anaerobes
Gram-positive spore-forming anaerobic bacilli
– _________
Clostridium
Frequently Encountered Anaerobes
Gram-positive spore-forming anaerobic bacilli
– Clostridium
Most from (endo or exo?) genous sources
Examples:_____,______,_______,______,________
Exo
tetanus, gas gangrene, botulism, food poisoning, pseudomembranous colitis (C. difficle)
Clostridium difficle is most often detected via _______________ detection
direct stool antigen
Frequently Encountered Anaerobes (cont’d)
Gram-positive non-spore-forming anaerobic bacilli
–PALMEB(________________________________)
– Most are from (Endo or Exo?) genous sources and are therefore ______
Actinomyces, Bifidobacterium, Eubacterium, Mobiluncus, Lactobacillus, and Propionibacterium
Endo
opportunists