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53 Cards in this Set
- Front
- Back
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Every member of the family Enterobacteriaceae is:
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-Gram neg bacillus
-Oxidase negative -Ferments glucose w or w/out gas -Reduces nitrate to nitrite -If it's motile, it's peritrichous -Facultative anaerobe -Has endotoxin |
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enterobacteriaceae are normal flora in
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the intestinal tract; they help us to digest our food
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What is endotoxin composed of?
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LPS
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what is the #1 cause of gram negative shock/sepsis
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escherichia coli
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symptoms of gnshock
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high fever, shaking chills, lowered blood pressure, peripheral circulatory failure, confusion, rapid death without treatment
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what antibiotics would we not even test enterobacteriaceae for, and why?
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penicillin
erythromycin clindamycin oxacillin/methicillin Enterobacter. always restist these! They're really for gram positives. |
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Nonpathogenic enterobacs group 1:ABC
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keschpemp
kleb, ecoli, serratia, citrobacter hafnia providencia, enterobacter, morganella, proteus |
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If the non-pathogenic bacteria DO cause an infection, what five could it be one of?
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UTI: most common it would be
Pneumonia: mostly from klebsiella Wound Infections: from self/others Sepsis: spread from 1' site to blood Neonatal Meningitis: from e.coli in the birth canal |
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the most effective group of antibiotics for the enterobacteriaceae are:
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pangcccskit
piperacillin, ampicillin, nitrofurantoin, gentamicin/tobramycin, carbenicillin cephalosporins chloramphenicol |
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5 genuses of enteric pathogens:
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-Shigella
-Edwardsiella tarda -Salmonella -Yersinia enterocolitica -Escherichia coli |
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how many species of shigella
what are they |
4
A: dysenteriae B: flexneri C: boydii D: sonnei |
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most encountered species of shigella:
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sonnei
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least encountered shigella
2/3 |
dysenteriae
flexneri, boydii |
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Shigellosis is aka
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bacillary dysentery
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difference between diahrrea and dysentery:
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water vs diahrrea with blood and mucous
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Shigellosis:
-transmission -mechanism of disease -incubation time before symptoms |
Anal to oral; through bad hygiene/food.
Necrosis; bugs invade cells of colon. 3 days (36-72 hrs) Staph only takes 2-6! |
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How is shigellosis treated?
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It's selflimiting after 3-7 days, otherwise use trimethoprim sulfamethoxazole (SXT) if necessary
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Most common symptom of Edwardsiella tarda; in whom?
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Diahhrea in fishtank cleaners
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what are the natural resorvoirs of edwardsiella tarda?
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fish and reptiles
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what is the most frequently encountered pathogen?
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salmonella
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2 diseases of salmonella
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Enterocolitis
Typhoid fever |
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what two bugs cause enterocolitis?
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Salmonella enteritidis (most often)
Salmonella typhimurium (2nd often) |
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what is antoher name for enterocolitis?
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salmonellosis
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incubation time for salmonellosis
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8-24 hrs
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Compare the disease mechanisms of Salmonella and Shigella
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Shigella causes necrosis of colon cells
Salmonella doesn't; it does invade them though. |
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symptoms of salmonellosis
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-Severe abdominal pain
-Fever no dysentary. |
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what organism causes typhoid fever?
how is it transmitted? |
Salmonella typhi
Bad hygiene, contaminated food/h2o from a carrier |
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symptoms of typhoid fever
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febrile disease: fever, headache, lethargy, cough, splenomegaly, hepatomegaly, rash, slight diarrhea.
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how is typhoid fever treated
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sulfamethoxazole trimethoprim SXT
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What does Yersinia enterocolitica cause
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enterocolitis
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what 3 organisms (not one genus) cause enterocolitis?
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Salmonella typhimurium,
Salmonella enterididis, Yersinia enterocolitica |
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How is Y. enterocolitica carried and transmitted?
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Carried in Intest. tracts of wild/domestic animals.
transmitted by ingestion of contaminated food/water |
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Symptoms of enterocolitis from y. enterocolitica:
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abdominal pain and diarrhea
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Growth requirements of Y. enterocolitica
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-does not grow well on enteric media;
-requires CIN media contains Cefsulodin, irgasan, and novobiocin. |
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two types of E.coli variations based on the diseases they cause
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Enteropathogenic - causes dysentery
Uncommon in U.S. Enterotoxigenic - causes Mexican diarrh. More common |
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What is the most typical e. coli strain we see as cause of disease?
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E. coli 0157:H7
grows on SMAC - sorbital MAC agar; Causes Hemolytic Uremic syndrome |
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What organism caused bubonic plague
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yersinia pestis
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What organism causes mesenteric lymphadenopathy?
Symptoms like? common or rare |
Yersinia pseudotuberculosis; symptoms are similar to appendicitis.
Rare |
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Pathogenic characteristics of Y. pestis
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Zoonotic disease transmitted by rodent bites;
Oxidase neg (where Pasteurella is +) Most common form is BUBONIC because of VERY LARGE inguinal or axillar lymphadenopathy. Uncontagious as bubonic, but pneumonic IS contagious |
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factor that makes S. typhi especially pathogenic
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can be transmitted from carriers - the organism is lodged in the gallbladder but it's asymptomatic
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another name for Hemorrhagic E. coli:
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0157-H7
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how is hemorrhagic e. coli transmitted?
what is the general resorvoir |
-undercooked beef
-apple cider -petting farms Resorvoir: Cows |
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Symptoms of hemorrhagic e. coli infection:
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severe cramps
-severe dysentery very bloody |
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culture media requirements of E.coli 0157:h7:
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SMAC - sorbital MAC --> allows differentiation of Hemorrhagic ecoli from others.
CT-SMAC: cefixine/tellurite + SMAC -> inhibits growth of other ecoli bugs |
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What is the difference btwn SMAC and MAC?
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SMAC has sorbitol;
pH indic: phenol red normal e.coli ferment sorbitol and turn pink; hemorrhagic does not, so remains clear. |
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what population is Hemolytic Uremic syndrome usually seen in?
what is the mechanism of the disease? |
elderly/young chidren
causes blood clots in kidneys, RBC lysis, renal failure. |
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Why is hemolytic uremic syndrome (HUS) difficult to treat?
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Treating with antibiotics inhibits normal flora and enables the pathogenic 0157-H7 to grow even better!
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how are enteric pathogens differentiated?
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1. screening specimens for enteric bugs
2. biochemical id 3. serological typing |
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3 antigen types on enterobacteria:
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O -> Somatic
H -> Flagella K -> envelope (capsular) |
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process of Otyping for salmonella:
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1. Apply PolyO antibody (against all 50 types of O)
If no agglutination: either not salmonella, or the H/K ag are masking O 2. Boil to destroy H/K antigens (heat labile) 3. Retest with PolyO; if agglutination: 4. Test with individual anti-sera ->most common is Anti-D, Anti-A,C 5. Subtype -> then do H serotype |
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what is PFGE essentially?
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pulsed field gel electrophoresis;
fingerprint-typing to match enteric bacterial strains that are same in various patients. |
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What bacteria are not serotyped?
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edwardsiella
enterocolitica |
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what do we know from positive fermentors on enteric agar?
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fermentation indicates normal flora
nonfermentors are POSSIBLE pathogens |
