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