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89 Cards in this Set
- Front
- Back
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Strep is easily seen in chains if a ________ sample is grown in a __________ media as opposed to a tissue sample.
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Strep is easily seen in chains in a PUS sample grown in a BROTH media as opposed to a tissue sample.
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What is the morphology and gram stain pattern of Staph?
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Gram positive cocci: looks like a bunch of grapes.
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T/F: Staphylococcus is oxygen tolerant/facultative anaerobe.
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True. Staph is an oxygen tolerant/facultative anaerobe.
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T/F: Staph forms spores.
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False. Staph does not form spores.
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When are spores formed? aka what type of environment?
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Spores are in a non vegetative stage like when bacteria hibernate. When the environment is not condusive to rapid growth, they go through spore forming stages where there is less growth until a favorable
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When grown on BAP, what color is Staph? What color is S. aureus?
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Staph usually white. S.aureus is golden yellow.
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What is the hemolytic pattern of S.aureus on BAP?
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S. aureus is beta hemolytic.
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What's an oxygen tolerant organism?
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One that prefers an anaerobic environment but can use oxygen if it has to.
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what does beta hemolysis look like on a BAP?
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A clear zone around the organism due to RBCs lysing.
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What is special about Staph's tolerance to heat & salt?
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Staph is heat tolerant up to 45 degrees C and salt tolerant up to 15% NaCl.
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Which staph species is coagulase positive?
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S. aureus
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What's the mechanism of coagulase?
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Coagulase protects the bug from phagocytosis by forming a clot (causes fibrin to clot). it walls itself off and helps the host = that's why they form localized abcesses. it also helps the bug keep itself from the host's immune system.
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Coagulase helps staph resist what?
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phagocytosis.
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is staph catalase + or - ?
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catalase positive, unlike strep which is catalase neg
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is staph oxidase + or - ?
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oxidase negative
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A gram positive cell wall has an identifying acid feature. what is this acid?
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teichoic acid
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what 3 clinically significant species are part of staph?
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s. aureus
s. epidermidis s. saprophyticus |
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which staph species causes UTI's?
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s. saprophyticus
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which staph species is found on the skin & is an opportunistic bug?
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s. epidermidis
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which staph species is not implicated except in endocarditis?
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s. epidermidis
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where would i find s. aureus?
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anterior nares in about 30-40% of people. also in the skin and other mucous membranes.
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where would i find s. epidermidis?
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skin!
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list some virulence factors of staph.
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hyaluronidase, protein A, coagulase, enterotoxin, hemolysin, TSST-1, lipase, DNAse, beta lactamase, penicillin binding proteins, leukocidin, and capsule.
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which virulence factor is known as the spreading factor?
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hyaluronidase.
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which virulence factor works by breaking down connective tissue, helping staph to spread?
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hyaluronidase.
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i am a virulence factor. i bind to the Fc portion of IgG and resist opsinization.
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Protein A
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i am a virulence factor. i help form clots. who am i?
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coagulase.
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i am a virulence factor. i cause toxic shock syndrome. who am i?
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TSST-1
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i am a virulence factor that causes RBCs to lyse. who am i?
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hemolysin
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what makes staph penicillin resitant?
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beta lactamase. it destroys the beta lactam ring that are in penicillin and cephaosporin (which work on cell walls).
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what makes staph methicillin resistant?
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PBP-2a = penicillin binding protein.
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what kills WBCs and RBCs?
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leukocidin
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what helps protect staph from phagocytosis?
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a capsule
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list some diseases caused by staph
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abscess, furncles/carbuncles, impetigo, skin scalded syndrome, toxic shock syndrome, osteomyelitis, pneuomnia, cellulitis, UTI (s. saprophyticus), food poisoning
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how would you differentiate btw the staph species? list 3 different tests you would use & their reactions.
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coagulase test = + for only s. aureus.
novobiocin sensitivity = R for s. saprophyticus. mannitol fermentation = + for only s. aureus |
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what test differentiates btwn staph & strep?
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catalase!
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how does catalase work?
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it breaks down H2O2 into water and oxygen.
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what does coagulase do?
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clots plasma
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what does lipase do?
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helps staph to be resistant to bactericidal effects of lipids in the skin
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what does penicillinase do?
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breaks down the beta lactam rings helping staph to be resitant to penicillin and cephalosporins.
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what do enterotxins do?
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they are heat stable (resist boiling for 30 mins), responsible for food poisoning.
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what does exfoliative (epidermolytic) toxins do?
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cause scalded skin syndrome (SSS). they act at desmosomes.
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what do hemolysins do?
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they lyze RBCs and WBCs
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what does leukocidin do?
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kill WBCs
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what does toxic shock syndrome toxins do?
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they are prototypical super antigens, men & women can get it. basically, it has non specific activation of T cells causing an overexuberant T cell response.
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what does protein A do?
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it's a single polypeptide chain found in the cell wall, unique to S. areus. it binds to Fc portion of IgG and causes a problem for opsinization. the macrophage that hs the Fc receptor can't bind to the antibody that is trying to get rid of these bugs. can spread if it breaks down hyluorinc acid.
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acute bacterial endocarditis is often found in which people?
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IV drug users
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what is a disease in young athletes that is known as infection of the bone?
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osteomyelitis
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S. aureus can cause acute endocarditis. T/F?
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true
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strep causes subacute endocarditis. t/f?
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true.
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staph infections are more of an intoxication than an infection. why?
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1. most common form of food poisoning
2 due to preformed enterotoxins 3 enterotoxins are produced when s. aureus grows in carbohydrate and protein foods----pasteries, custards, potato salad. . . |
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food poisoning by staph occurs how?
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damage is done by toxins and not by the bacteria. bacteria forms the toxin and when you ingest it you will get sickk. we treat for intoxication, not infection.
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what's the treatment for food poisoning by staph?
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give electrolytes and fluid. tylenol to lower the fever. antibiotic treatment is NOT indicated bc staph is a self limiting bug. it is an intoxication and not an infection!
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what is the incubation period of staph and when do symptoms occur?
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short incubation period = 2-4 hrs. symptoms come in about 4-6 hrs = very rapid
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what are the symptoms of food poisoning by staph?
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severe abdominal distress, diarrhea, and NO FEVER
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will fever be part of the food poisoning caused by staph?
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no, no fever
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is staph found in the stool of those who are food poisoned by staph?
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no, bc it is an intoxication and not an infection.
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is the stool positive for staph after an enterocolitis infection?
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yes
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why does staphylococcal enterocolitis occur?
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results of microbial imbalance, following use of antibiotics
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what are the symptoms of TSS?
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fever, rash, hypotension, desquamative skin rash, acute multisystem illness.
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can TSS be found in men?
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yes.
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TSS can be caused by which 2 organisms?
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staph and strep!
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what is the incubation period of staph and when do symptoms occur?
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short incubation period = 2-4 hrs. symptoms come in about 4-6 hrs = very rapid
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what are the symptoms of food poisoning by staph?
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severe abdominal distress, diarrhea, and NO FEVER
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will fever be part of the food poisoning caused by staph?
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no, no fever
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is staph found in the stool of those who are food poisoned by staph?
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no, bc it is an intoxication and not an infection.
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is the stool positive for staph after an enterocolitis infection?
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yes
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why does staphylococcal enterocolitis occur?
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results of microbial imbalance, following use of antibiotics
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what are the symptoms of TSS?
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fever, rash, hypotension, desquamative skin rash, acute multisystem illness.
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can TSS be found in men?
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yes.
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TSS can be caused by which 2 organisms?
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staph and strep!
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what is the incubation period of staph and when do symptoms occur?
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short incubation period = 2-4 hrs. symptoms come in about 4-6 hrs = very rapid
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what are the symptoms of food poisoning by staph?
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severe abdominal distress, diarrhea, and NO FEVER
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will fever be part of the food poisoning caused by staph?
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no, no fever
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is staph found in the stool of those who are food poisoned by staph?
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no, bc it is an intoxication and not an infection.
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is the stool positive for staph after an enterocolitis infection?
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yes
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why does staphylococcal enterocolitis occur?
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results of microbial imbalance, following use of antibiotics
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what are the symptoms of TSS?
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fever, rash, hypotension, desquamative skin rash, acute multisystem illness.
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can TSS be found in men?
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yes.
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TSS can be caused by which 2 organisms?
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staph and strep!
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list some tests used to diagnose staph.
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gram stain, culture on BAP, coagulase, catalase, antibiotic sensitivity testing.
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if you are still waiting for confirmation of staph aureus, what type of treatment is indicated?
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board spectrum antibiotics
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penecillins and cephalosporins are no effective on ______________________.
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beta lactamase producing staph species
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what is the principle way by which S.aureus becomes resistance to antibiotics?
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chromosomes
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T/F: antibiotic resistance for s. aureus is ONLY mediated by chromosomal mediated process.
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false
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the larger the zone of inhibition, the more susceptible the bacteria. T/F.
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true
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bacteriophage transduction is responsible for spread of antibiotic resistance.T/f
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true
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drug resistance genes are under plasmid control. t/f
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true
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prevention of staph diseases includ: good hygeine, judicious use of antibiotics, sterile techniques for procedures, steriolization. . . t/f/
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true
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