Anaerobes and Biofilm Flashcards
What two characteristics make an organism an anaerobe?
1-Do not require oxygen for life and reproduction
2-Oxygen’sdirect toxic effect may prohibit their growth
What are 3 toxic or free radical oxygen products?
1-O2- (Superoxide)
2-H2O2 (Hydrogen Peroxide)
3-OH. (Hydroxyl Radical)
Why are anaerobes referred to as “Party Animals”?
Sites colonized with mixtures of organisms frequently provide conditions favorable to the growth of anaerobes.
*Volatile/foul smelling metabolic byproducts of anaerobes contribute as well
What are the 2 main natural habitats for anaerobes?
1-Enivornmental/exogenous (ie. Clostridium due to spores)
2-Endogenous (mouth, vagina, bowel, skin)
Fusobacterium, Veilonella, actinomyces, pigmented porphyromonas and prevotella sp. are typical of what site?
Oral
Propionibacterium are typical of what site?
Skin
Lactobacillus and prevotella bivia are typical of what site?
Vagina
Bacteroides fragilis and other bacteroides species are typical of what site?
Colon
What are 4 main pre-disposing factors for anaerobic infection?
1-Trauma to mucous membranes or skin (trauma may also allow access to deeper tissues)
2-Vascular stasis (poor oxygenation)
3-Tissue necrosis
4-Decrease of redox potential of tissues
Spore-forming gram-positive rods are which family of anaerobes?
Clostridium species
What are the 4 most common clostridium species?
1-C. tetani (tetanus)
2-C. perfringenes (gas gangrene)
3-C. botulinum (botulism)
4-C. difficile (pseudomembranous colitis)
Which two main families of anaerobes are Non-spore forming gram positive rods?
1-Actinomyces
2-Propionibacterium
Chronic granulomatous, infectious disease with sinus tracts and fistulae, which erupt to the surface and drain pus containing sulfur granules is typical of which anaerobe?
Actinomyces
Which anaerobe is normal skin and respiratory flora, and causes similar infection to coagulate negative staph?
Propionibacterium
*P. acnes often found in acne pustules
What two anaerobic species are the gram-possitve cocci?
1-Peptostreptococcus (can go to brain or deep lung)
2-Anaerobic and microaerophillic streptococcus (do not respond to metronidazole)
Which anaerobic species is gram-negative cocci?
Veillonella species
*only gram-neg cocci anaerobes implicated as pathogenic. Found in mixed infections of oral origin
What are the 3 main gram-negative rod anaerobes?
1-Bacteroides (70% of clinically significant bacteremia)
2-Prevotella and porphyromonas (mouth flora and dental abscesses)
3-Fusobacterium (mouth sometimes with actinomyces)
What are 3 main ways to treat anaerobic infection?
1-Create an environment in which anaerobes cannot proliferate (drainage, debridement etc)
2-Arrest the spread of anaerobes into healthy tissue (antimicrobials)
3-Neutralize toxin
What are the 3 main steps to biofilm formation?
1-attachment of cells to substrate
2-growth and aggregation of cells
3-maturation and maintenance of architecture
What are the 5 stages of biofilm formation?
1-Attachment (seconds)
2-Irreversible binding (minutes, cells are sessile)
3-Layering/maturation (greater than 10 um thick)
4-Ultimate thickness/maturation (days, greater than 100 um thick)
5-Dispersion (several days, cells become planktonic)
What are 3 construction characteristics of biofilms?
1-Stalks and mushroom-shaped microcolonies
2-Matrix of EPS, proteins and DNA
3-Fluid-filled channels
What are the 3 layers of a mature biofilm?
1-Outer (most exposed to nutrients, most active, some become planktonic)
2-Intermediate (metabolism down-regulated, still using nutrients and exchanging genes)
3-Innermost (attached, earliest, least active, includes persister cells)
What are the 3 cell types in biofilms?
1-Planktonic (free living)
2-Sessile (attached/participating in biofilm)
3-Persister (inert, in all biofilms)
After the acquired pellicle made up of protein and glycopeptides, what two organisms typically colonize first in dental plaque?
1-Streptococcus mutans
2-Actinomyces
*Glucan polymer glycocalyx
Which bacteria is an example of a bridge bacteria that cannot bind the pellicle but can bind to primary colonizers?
Fusobacterium
What are 5 examples of late colonizers?
1-Streptococcus salivarius 2-Propionibacterium 3-Prevotella 4-Veillonella 5-Selenomonas
*generally considered non-pathogenic
What are 4 pathogens that require late colonizers in order to attach?
1-Porphyromonas gingivalis
2-Bacteroides forsythia
3-Aggregatibacter actinomycetemcomitans
4-Treponema denticola
