Shared Flashcard Set

Details

anaerobic bacteria
cmbm exam IV
68
Chemistry
Graduate
01/21/2010

Additional Chemistry Flashcards

 


 

Cards

Term
what are obligate, (strict), anaerobes?
Definition
O2 is toxic
Term
what are aerotolerant anaerobes?
Definition
do not use O2, but can tolerate low levels of it
Term
what are facultative anaerobes?
Definition
grow in the presence or absence of O2
Term
what are microaerophilic organisms?
Definition
these utilize O2, but only grow in the presence of low O2
Term
what gram+ anaerobic cocci should we know?
Definition
peptostreptococcus
Term
what spore-forming gram+ anaerobic bacilli should we know?
Definition
clostridium
Term
what nonspore-forming gram+ anaerobic bacilli should we know?
Definition
actinomyces, lactobacillus, mobiluncus, and propionibacterium
Term
what are anerobic gram- bacilli we should know?
Definition
bacteroides, fusobacterium, porphyromonas, prevotella
Term
what are anerobic gram- cocci we should know?
Definition
veillonella
Term
of the anaerobes, what are the most common pathogens?
Definition
clostridium, bacteroides, fusobacterium, and peptostreptococcus
Term
of the anaerobes, which are potential pathogens?
Definition
prevotella, veillonella, porphyromomas, actinomyces
Term
of the anaerobes, which are opportunistic pathogens?
Definition
bifidobacterium, eubacterium, lactobacillus, mobiluncus, (can be associated with bacterial vaginosis), proprionibacterium, (can be associated with acne)
Term
what are sites colonized by aneaerobic bacteria?
Definition
mucosal surfaces (colon, urogenital tract, oral cavity: gingival crevices, tonsillar crypts, tooth surfaces) and hair follicles
Term
is anaerobic bacterial growth facilitated by other bacteria? what about aerotolerant bacteria?
Definition
anaerobic bacterial growth can be facilitated by facultative organisms. aerotolerant bacteria can also co-colonize with facultative organisms. in both instances the facultative organisms use up the O2, creating a microenvironment. in many places in the body such as the oral cavity and colon, anaerobes outnumber aerobes >1000:1
Term
what are the predominant anaerobic bacteria in the oral cavity, upper respiratory tract?
Definition
peptostreptococcus, actinomyces, porphyromonas, prevotella, fusobacterium, veillonella
Term
what are the predominant anaerobic bacteria in the gastrointestinal tract?
Definition
peptostreptococcus, bacteroides, fusobacterium
Term
what are the predominant anaerobic bacteria in the skin?
Definition
propionibacterium
Term
what are the predominant anaerobic bacteria in the genitourinary tract?
Definition
mobiluncus, prevotella, lactobacillus
Term
how are most anerobic infections acquired? are there any exceptions?
Definition
most infections are endogenously acquired from the normal flora, except for clostridium which is a spore that can be picked up from the environment
Term
are there more than one kind of anaerobic bacteria often involved in an infection?
Definition
yes, infections are often polymicrobial consisting of a mixture of several different kinds of anaerobes and facultative organisms
Term
can anaerobic organisms form abscesses?
Definition
yes infections with anaerobic bacteria often involve abscesses
Term
what are some tell-tale signs of anaerobic bacterial infection?
Definition
foul odor and gas
Term
how do anaerobic flora cause pathogenesis in the same body? what are some examples with the lungs or peritoneal cavity?
Definition
normal anaerobic flora can become pathogenic at a sterile site, such as with pneumonia, (caused by aspiration of oral flora), infection of the peritoneal cavity, (after abdominal sx), or tissue infections due to trauma or tissue damage, (impaired blood flow increases anaerobic infection risk)
Term
what is a common way to get an anaerobic bacterial infection intra-abdominally?
Definition
bowel perforations, (due to sx or injury), can cause abcesses, wound infections, or peritonitis via bacteroides, peptostreptococcus, fusobacterium, + facultative organisms
Term
how do pulmonary anaerobic infections occur?
Definition
peptostreptococcus, fusobacterium nucleatum, actinomyces and prevotella melaninogenica can be aspirated from the oropharynx causing abcesses, necrotizing pneumonia, and aspiration pneumonia
Term
how can anaerobic bacteria cause pelvic infections?
Definition
gynecologic sx or malignancies can lead to infection by prevotella bivia and prevotella disiens, fusobacterium, and bacteroides, leading to tubo-ovarian abscesses or salpingitis
Term
how can brain abcesses be caused by anaerobic bacteria?
Definition
peptostreptococcus, fusobacterium and prevotella from the oral cavity, (often associated with a hx of chronic sinusitis/otitis), can disseminate from the blood across the BBB
Term
what kinds of anaerobic bacteria cause skin+soft tissue infections, what are they characterized by? what kinds of infections affect the skin and tissue?
Definition
clostridium perfringens alone or in a mixed infection with peptostreptococcus, bacteroides, S. aureus, Str. pyogenes or gram - aerobic/facultative organisms can cause necrotic tissue, foul smell and gas. gas gangrene, myonecrosis, necrotizing fascitis, crepitant cellulitis and bite wounds are all examples of these infections
Term
what kinds of anaerobic bacteria can cause oral and dental infections? what kinds of infections can they cause? what is an associated risk with these infections?
Definition
porphyromonas are associated with periodontal infections as well as actinomyces, prevotella, fusobacterium, peptostreptococcus, and veillonella. these can cause dental abscesses, gingivitis, chronic sinusitis, and chronic otitis. these can disseminate into the blood or CNS from this area, causing even worse problems
Term
what anaerobic bacteria can cause bacteremia and endocarditis?
Definition
bacteroides fragilis is the most common anaerobe associated with bacteremia
Term
how do actinomyces react to O2? what is their gram stain? what is their shape? where are they found? what kinds of infections are they associated with?
Definition
actinomyces are gram + aerotolerant anaerobes. they are filamentous bacteria and are endogenously found in the mouth. they can cause cervivofacial infections, (face, neck, jaw), following injury or dental work, and aspiration of actinomyces can cause thoractic infection
Term
where can actinomyces cause abcesses? what do the lesions resemble?
Definition
actinomyces can cause abcesses in the lung, chest wall, abdominal cavitiy, pelvic area and brain. these lesions resemble subcutaneous mycoses and are chronic and slow developing with pus and draining sinuses. the pus contains colonies of the organism, called sulfur granules.
Term
what genus of bacteria is responsible for the most common cause of serious anaerobic infection? where does the most common form infect? what is its virulence factor? how does its LPS affect hosts? where is it found?
Definition
bacteroides, the most important pathogen of which is B. fragilis. bacteroides fragilis is the most important pathogen of the genus, a common cause of abdominal infection due to it's polysaccharide capsule, however its LPS has little endotoxin activity due to an atypical lipid A. bacteroides is very prevalent in the colon, called the "E. coli" of anaerobic bacteria
Term
what is the relationship between bacteroides, polyphyromonas, and prevotella?
Definition
many bacteroides species have been re-classified as porphyromonas or prevotella
Term
what does prevotella melaninogenica usualy infect? does it have a capsule?
Definition
prevotella melaninogenica typically infects above the diaphragm and it does make a capsule
Term
what are both prevotella bivia and disiens both associated with?
Definition
gynecologic infections
Term
what kind of infection is porphyromonas associated with?
Definition
dental abcesses and gingivitis
Term
what shape are fusobacterium? gram stain? where do they normally inhabit? what infections are they associated with? which is the most common species?
Definition
fusobacterium are gram - rods w/pointed ends. they are normal flora of the mouth, colon and female genital tract. they can cause oral, brain, pulmonary, intra-abdominal, or pelvic abscesss, (usually mixed infections, but this or bacteriodes are usually dominant). fusobacterium nucleatum is the most common species
Term
what kind of metabolism do lactobacillus have? where are they found and what useful function to they perform? what kind of pathogen are they? can they cause UTIs?
Definition
lactobacillus can be facultative or obligate anaerobes. they colonize the female genital tract, fermenting and keeping the pH low via lactic acid, which protects against bacterial vaginosis. they are opportunistic pathogens, but cannot grow in urine, so rarely does lactobacillus cause UTIs. (if lactobacillus is found in a urine cx, the conclusion will be that it was contaminated)
Term
how is mobiluncus considered in terms of gram staining? what kinds of infection is it associated with? what kind of pathogen is it?
Definition
mobiluncus appears gram -/+ variable, but is classifies gram + b/c of its cell wall composition. it is associated with bacterial vaginosis along with the facultative organism, gardnerella vaginalis. mobiluncus is an opportunisitc pathogen
Term
what is peptostreptococcus an anaerobic version of? where is it found? what kinds of infection can it cause? what does it often participate in mixed infections with?
Definition
peptostreptococcus is an anaerobic version of streptococci. it is a part of normal flora in the mouth & colon. it can cause periodontal disease, peritontis, intra-abdominal abscesses, pulmonary, skin & genital infections. it is also a part of mixed infections with bacteriodes or facultative organisms
Term
where is proprionibacterim found, what species is associated with acne?
Definition
proprionibacterium is found on the skin and GI tract, and proprionibacterium acnes is an opportunistic contributor to acne
Term
where is veillonella found? shape/gram stain? what kinds of infections is it associated with?
Definition
veillonella is gram - cocci (only one), part of normal flora in the mouth, it is an opportunistic pathogen associated with mixed infections. it is found in abscesses of the sinuses, tonsils, and brain, and may be associated with human bites
Term
what is different about clostridium? gram stain? where is it found? what toxins can it produce?
Definition
clostridium is a gram + spore former, (only anaerobe that does this). they are usually obligate anaerobes, though some are aerotolerant. they are ubiquitous in the soil, water, and sewage - thus are usually exogenous infectors, but sometimes are seen in human/animal GI tracts. they produce neurotoxins, enterotoxins, hemolysins, and a variety of tissue-damaging enzymes
Term
what are the 4 clostridium pathogens we should know?
Definition
clostridium botulinum (botulism), difficile (antibiotic-associated diarrhea, pseudomembranous colitis), perfringes (food poisoning, nectrotizng enteritis, cellulitis, gas gangrene, septicemia), and tetani, (tetanus)
Term
what do you often not see in tissue or cx's of clostridium perfringens? how do they hemolyse?
Definition
spores are not usually seen. clostridium perfringes create double zones of hemolysis when cultured, (immediate beta, and surrounding alpha zones)
Term
what clinical diseases are associated with clostridium perfringes?
Definition
cellulitis, (only connective tissue, no muscle), suppurative myositis, (fascitis, pus, but no muscle necrosis), myonecrosis, (gas gangrene, necrosis of muscle), food poisoning, (enterotoxin), enteritis necroticans, (toxin-dependent, severe food poisoning w/tissue damage in colon)
Term
what is the most common type of clostridium perfringens? how are the types classified? where are B-E found?
Definition
type of clostridium perfringens is dependent on combination of 4 lethal toxins, w/type A being the most common, (present in the environment). types B-E colonize the GI tract of animals, sometimes humans
Term
what is the alpha toxin produced by clostridium perfringens? how does it act? what cells can it affect?
Definition
the alpha toxin is a lethal phospholipase C, (lecthinase), that degrades lecithin in cell membranes, lysing endothelial cells, erythrocytes, leukocytes and platelets
Term
what is the beta toxin produced by clostridium perfringens? how does it act? what disease can it cause?
Definition
the beta toxin can cause necrotizing activity in the intestinal mucosa, it is responsible for enteritis necroticans via type C clostridium perfringens, (lethal toxin)
Term
how does the epson toxin of clostridium perfringens affect the GI wall?
Definition
it can increase the vascular permeability, contributing to a type of diarrhea. (lethal toxin)
Term
what are the 2 toxins produced by clostridium perfringens? what kinds of infections does it cause? is enterotoxin a lethal toxin? what does it cause? how does it act?
Definition
group A clostridium perfringens is responsible for most human infections, producing both alpha toxin and enterotoxin. enterotoxin causes food poisonin, but is not lethal like the alpha toxin. it is a heat labile protein that binds to epithelial cells in the small intestine and disrupts ion transport, leading to fluid loss and watery diarrhea.
Term
how does clostrium perfringens cause gas gangrene/myonecrosis?
Definition
spores enter the tissue from soil and toxins damage/kill the cells. enzymes, (collagenase, hyalurnidase), facilitate spread and metabolic activity of the organisms leads to creptitation, (gas formation). copious and foul smelling exudates are seen and dissemination of the toxins can lead to shock, renal failure and death.
Term
how does clostridium perfringens from a wound, (as opposed to a cx), respond to gram staining?
Definition
a gram stain of clostridium perfringens will show some positive, some not, (doesn't maintain stain well). the exudate will also not show many neutrophils, b/c the alpha toxin lyses them
Term
what is the appearance of clostridium tetani? where does it infect? what toxin does it produce? can it be vaccinated against?
Definition
clostridium tetani appear as terminal spores, (drumsticks). this organism remains localized in wounds, but produces a neurotoxin called tetanospasm. tetanospasm is a heat-labile neurotoxin, but a toxiod is made in the US that can vaccinate pts
Term
what kind of toxin is tetanospasm? where does it travel to? what do the AB subunits do? how does it affect the CNS?
Definition
tetanospasm is an A-B toxin that travels to inhibitory neurons via blood or retrograde neuronal transport. the B chain binds to neurons and the A chain blocks the release of inhibitory neurotransmitters, (GABA), leading to unregulated excitation and spastic paralysis, (constant contraction)
Term
what is the incubation period for tetanus? what muscles are affected? what happens if these muscles are affected?
Definition
the incubation period for tetanus is 4 days->several weeks. spastic paralysis can affect the jaw muscles, causing trismus/lockjaw or risus sardonicus, a "smile" resulting from contraction of facial muscles. if the back muscles are affected, opisthotonos (severe arching) occurs. if chest muscles are affected, respiratory failure leading to death can occur.
Term
what is the shape of clostridium botulinum?
Definition
with a drumstick shape, clostridium botulinum can be foodborne, (consuming home-canned goods, ingestion of the toxins, not the organism is sufficient), infant, (ingestion of spores in honey), or wound, (rare contaimination of wound with spores)
Term
is the neurotoxin produced by clostridium botulinum heat-labile? what is it similar to? is it complexed with anything? what nerves its it specific for? where does the B subunit bind? what is its main action?
Definition
the toxin of clostridium botulinum is a heat-labile neurotoxin, similar in structure/function to the tetanus toxin. it is complexed with non-toxic proteins which protect it in the GI tract. the B subunit binds to the receptors on motor neurons, remaining at the neuromuscular junction. it is very specific for cholinergic nerves and prevents release of ACh at these neuromuscular junctions. it prevents contractions, causing a flaccid paralysis.
Term
what is the main difference between the tetanus and botulism toxins?
Definition
tetanus produces spastic contraction, where botulism prevents contraction
Term
what are symptoms of botulism? is there fever/sepsis?
Definition
symptoms of foodborne botulism include blurrd vision, dry mouth, constipation, abdominal pain 1-3 days after ingestin contaminated food beginning with bilateral descending weakness of peripheral muscles, progressing to respiratory paralysis. there is no fever or sepsis associated.
Term
why is recovery from foodborne botulism prolonged? what is diagnosis based on? what is the mortality rate in the US?
Definition
the neurotoxin is irreversibly found the neurons, so recovery consists of regrowth of nerve endings. diagnosis is based on demonstrating toxin activity, rather than organism presence. mortality in the US is low due to supportive care
Term
what is floppy baby syndrome? how is botulism poisoning different in infants? what are symptoms? how is it detected?
Definition
infant botulism, due to consumption of food contaminated with botulism toxin, (honey, formula). clostridium botulism colonizes the GI tract of infants, (normal flora in adults prevents this), leading to constipation, feeding problems, lethargy, and poor muscle tone. toxin or organism can be detected in stool
Term
where are the spores located in clostridium difficle?
Definition
in the center of the organism. clostridium difficle is a minor component of normal intestinal flora, but it can infect pts on antibiotic therapy, (such as clindamycin, cephalosporins, fluroquinolones). it is responsible for antibiotic-dependent GI disease which ranges from mild diarrhea to severe pseudomembranous colitis
Term
how is c. difficle different from other clostridium?
Definition
it can be endogenous
Term
when do clostridium difficle infections start to appear? how are they transmitted in the hospital? what is treatment for it? how is it diagnosed?
Definition
c. difficle infections typically occur 5-10 days after starting antibiotic tx, (though can take up to 10 wks). the spores are present in hospital settings, leading to nosocomial outbreaks of c. difficile GI disease. tx includes discontinuing the implicated antibiotic, metroconidazole or vancomycin, which kills vegetative forms, but not spores. it is diganosed by detecting toxins in stool, (ELISA)
Term
what are the toxins produced by c. difficle?
Definition
enterotoxin, (toxin A), which is chemotactic for neutrophils, inducing cytokine production and increasing permeability of the intestinal wall with hypersecretion of fluid. cytotoxin, (toxin B), induces depolymerization of actin with loss of cellular cytoskeleton
Term
where are c. difficle cx's best performed? can swabs be used?
Definition
absecesses via needle/syringe, CSF, pleural, or synovial fluid, or material from sx or deep wound, none of which can be exposed to O2. swabs are not acceptable due to possibility of contamination with normal anaerobic flora
Supporting users have an ad free experience!