Term
| What are the characteristics of Enterobacteriaceae? |
|
Definition
Gram (-), facultative anaerobic rod
Ferments glucose
Oxidase negative
Reduce nitrates to nitrites
Motile by pertrichous flagella |
|
|
Term
| What characteristics of enterobacteriaceae are used to distinguish from Pseudomonas? |
|
Definition
Ferments glucose
Oxidase negative |
|
|
Term
| What characteristic of Enterobacteriaceae can be used as a diagnostic in a urine dip stick test? |
|
Definition
| Reduce Nitrates to Nitrites |
|
|
Term
| What Enterobacteriaceae are non-motile? |
|
Definition
|
|
Term
| What type of media is used to isolate Enterobacteriaceae? Why? |
|
Definition
MacConkey agar
contains:
bile salts and crystal violet that inhibit gram +
pH indicator and lactose - E. coli ferment lactose, Shigella and Salmonella do not |
|
|
Term
| What color does E.Coli change the MacConkey agar? |
|
Definition
yellow -> Red Because E.Coli ferments lactose to acid decreasing pH
(lactose negative bacteria like Shigella and Salmonella grow white colonies) |
|
|
Term
| What antigens are used in classification/typing of Enterobacteriaceae? |
|
Definition
K antigens (capsular polysaccharide)
H antigens (flagellar proteins)
O antigens (somatic - on LPS) |
|
|
Term
| What color do Lac- organisms appear on MacConkey agar? |
|
Definition
|
|
Term
| What are the characteristics of Non-inflammatory diarrhea? |
|
Definition
(ETEC, Vibrio cholera)
Watery, high volume usually due to enterotoxin Low Grade Fever or No Fever Non-invasive No Fecal Leukocytes |
|
|
Term
| What are the Characteristics of Inflammatory Diarrhea? |
|
Definition
(
Less Volume Invasion of epithelium, Cytotoxins Fecal Leukocytes - methylene blue positive Fever Dysentery Blood and mucus in feces Tenesmus Lower quadrant cramping |
|
|
Term
| If diarrhea persist for >2 wks what should be considered? |
|
Definition
Parasites
Cryptosporidium and Giardia |
|
|
Term
| What should be considered in a patient with Chronic Diarrhea? |
|
Definition
|
|
Term
| What should be done for patients with non-inflammatory diarreah suffering from dehydration? |
|
Definition
Oral Replacement Therapy of water/glucose/salts
Anti-motility drugs
Antibiotics in some cases |
|
|
Term
| What should be done for patients suffering from inflammatory diarrhea? |
|
Definition
Rehydration
Antibiotics
Anti-motility drugs CONTRAINDICATED |
|
|
Term
| What organism are antibiotics contraindicated for? |
|
Definition
EHEC
enterohemorrhagic E. coli |
|
|
Term
| What is Clostridium difficile enterocolitis treated with? |
|
Definition
|
|
Term
| What are 4 complications seen in inflammatory bacterial diarrheas? |
|
Definition
Hemolytic Uremic Syndrome - EHEC
Disseminated infection - Susceptible populations
Guillain-Barre syndrome - campylobacter
Postinfectious arthritis - Shigella, Camphlobacter, Yersinia, Salmonella |
|
|
Term
| E. Coli Culture characteristics |
|
Definition
| Lac + Ferments glucose with gas (H2) Does not produce H2S Motile KIA Slant - All Yellow, raised in tube |
|
|
Term
| Salmonella cultural characteristics |
|
Definition
H2S+
Gas +
(except S. typhi)
KIA Slant - Yellow Butt, Raised in tube |
|
|
Term
| Shigella cultrue characteristics |
|
Definition
H2S (-)
No Gas
KIA Slant - Yellow Butt, not raised(no gas) |
|
|
Term
|
Definition
|
|
Term
| What are the symptoms of EHEC? |
|
Definition
Mild watery diarrhea -> hemorrhagic colitis
Severe cramping
Bloody diarrhea
Low or No Fever
No fecal Leukocytes |
|
|
Term
| What complications can occur in children <5 or elderly with EHEC? |
|
Definition
| Hemolytic uremic Syndrome |
|
|
Term
| Symptoms of Hemolytic uremic syndrome? |
|
Definition
Anemia
Low Platelet count
acute kidney failure
Can develop seizures or strokes |
|
|
Term
| What is the major reservoir of EHEC? |
|
Definition
|
|
Term
| What is the infectious dose of EHEC for humans? |
|
Definition
|
|
Term
| What type of cytotoxins does EHEC produce? |
|
Definition
Shiga-like toxins, inhibits protein synthesis
dissemination to kidney causes HUS |
|
|
Term
| What is responsible for the diarrhea caused by EHEC? |
|
Definition
| LEE - Locus of enterocyte effacement |
|
|
Term
| How does LEE allow adhesion of the bacterium to the host cell? |
|
Definition
| secreted protein that incorpartes into enterocyte membrane to for a pedestal where bacterium can bind |
|
|
Term
| Why is EHEC not treated with antibiotics? |
|
Definition
| Does not alter the severity of colitis and encourages development or HUS |
|
|
Term
|
Definition
Sorbitol MacConkey agar
O157:H7 is sorbitol negative so will show up white on agar |
|
|
Term
| WHat is the most common cause of Traveler's Diarrhea? |
|
Definition
| ETEC - Enterotoxigenic E. Coli |
|
|
Term
| What kind of virulence factors does ETEC produce? |
|
Definition
Heat-labile toxin
Heat-Stable toxin
Fimbriae adhesion species specific |
|
|
Term
| What E. coli has a toxin that's mechanism of action is identical to cholera toxin? |
|
Definition
|
|
Term
| What is the mechanism of action of ETECs heat labile toxin? |
|
Definition
| Activates adenylate cyclase-> increase cAMP-> activates Protein Kinase A-> Phosphorylates CFTR-> Cl flows out, NA and water follow |
|
|
Term
| What is the mechanism of the Heat Stable toxin of ETEC? |
|
Definition
| Activates guanylyl cyclase-> increases cGMP-> activates protein kinase A-> phosphorylates CFTR |
|
|
Term
| What E. coli closely resembles Shigella? |
|
Definition
| EIEC - Enteroinvasive E. Coli |
|
|
Term
| How is EIEC unlike other E. coli? |
|
Definition
non-motile
Do not decarboxylate lysine
Do not fement lactose |
|
|
Term
| What E. coli is responsible for 90% of UTIs? |
|
Definition
| Uropathogenic E. Coli (UPEC) |
|
|
Term
| What are the symptoms of a UTI? |
|
Definition
frequency
dysuria
pyuria
suprapubic pain
cloudy urine
Cramping
Low Grade Fever or Afebrile |
|
|
Term
| What are the virulence factors of UPEC? |
|
Definition
P fimbriae (PAP pili)
hemolysin
sideropore
capsule (K-antigen) |
|
|
Term
| What is the major determinant of virulence amoung strains of E. coli that cuase neonatal meningitis? |
|
Definition
|
|
Term
| What is the agent of typhoid fever? |
|
Definition
|
|
Term
| What are the characteristics of Salmonella? |
|
Definition
| Lac- ferment glucose with gas (except typhi) Produce H2S |
|
|
Term
| What is of major importance in identificaiton of Salmonella? |
|
Definition
|
|
Term
| What salmonellae is incapsulated? |
|
Definition
|
|
Term
| What species of Salmonella is medically important? |
|
Definition
|
|
Term
| What are the 2 most frequent serotypes of Salmonella that cause disease in the US? |
|
Definition
S. enteritidis
S. Typhimurium |
|
|
Term
| What are the sources of Salmonella? |
|
Definition
| contaminated meat, dairy products, poultry, eggs, pet reptiles, turtles |
|
|
Term
| What are the symptoms of Salmonella gastroenteritis? |
|
Definition
Appears 20-72 hrs after infection
Inflammatory Diarrhea
Nausea, vomiting, followed by or concomitant with abdominal cramps and diarrhea.
Fever in 1/2
May be blood in stools |
|
|
Term
| How does salmonella infect the gut? |
|
Definition
enters through M cells in distal small intestine, proximal large bowel.
establishment a localized infection within the lamina propria |
|
|
Term
| Who is bacteremia and disseminated infection of Salmonella a problem for? |
|
Definition
Anyone with T cell deficiencies:
AIDS, Hodgkins, skeletal prosthesis, atherosclerotic plaque, elderly and the very young, sickle cell children |
|
|
Term
| What does S. Typhi infect? |
|
Definition
| exclusively a parasite of humans |
|
|
Term
| What are the symptoms of Typhoid Fever? |
|
Definition
High Fever, Slow Pulse, headache, mental confusion
Maybe a skin rash
May be constipated
Disseminated to RES organs |
|
|
Term
| what are the virulence mechanisms of S. Typhi? |
|
Definition
Type III secretion systmes:
-injects proteins into M cells to induce entry
-injects proteins in macrophages, allowing survival and disseminated disease. |
|
|
Term
| How is Typohid fever diagnosed? |
|
Definition
Culture of blood and feces
Serotyping for Vi capsule antigen
(feces may not be positive until late in infection) |
|
|
Term
| What species of Shigella produces ~1000x more shiga toxin than other shigellae? |
|
Definition
|
|
Term
| Where are S. dysenteriae epidemics found? |
|
Definition
| South and Central America |
|
|
Term
| What species of Shigella is associated with disease in the Indian Subcontinient? |
|
Definition
|
|
Term
| What is the cause of 70% of all shigellosis in the US? |
|
Definition
|
|
Term
| What is the Second most common Shigella found in the US, most common in gay men? |
|
Definition
|
|
Term
| What is the sole source of Shigella infection and what is the route of infection? |
|
Definition
Humans are sole source
fecal-oral route |
|
|
Term
| Who and where is Shigella most common? |
|
Definition
Children
Day care centers
mental instiutions and jails |
|
|
Term
| What is the pathogenesis of Shigella? |
|
Definition
1. Entry into microfold cells in gut
2. Escape from phagocytic vesicle
3. Extension to neighboring enterocytes |
|
|
Term
| What are the symptoms of Shigellosis? |
|
Definition
Watery diarrhea with abdominal pain-> 1-2 days colon is involved-> Scant, bloody diarrhea with pus/mucus-> severe cramps, tenesmus, high fever
(Like EIEC) |
|
|
Term
| What is prominent in the feces from Shigellosis? |
|
Definition
| Fecal leukocytes, often in sheets |
|
|
Term
| What can Shigella dysenteriae cause? |
|
Definition
|
|
Term
| What are the characteristics of Shigellae? |
|
Definition
Lac(-)
No gas from glucose
Nonmotile
H2S(-) |
|
|
Term
| What Shigellae produces high amounts of cytotoxins? |
|
Definition
|
|
Term
| What is the reservoir of Yersinia enterocolitica? |
|
Definition
|
|
Term
| What are large outbreaks of Yersinia enterocolitica associated with? |
|
Definition
|
|
Term
| What is the main source of Yersinia enterocolitica in the US? |
|
Definition
|
|
Term
| What are the symptoms of Yersinia enterocolitica, what can it mimic? |
|
Definition
fever, diarrhea, abdominal pain
Mimic appendicitis |
|
|
Term
| What is a complication of Yersinia enterocolitica? |
|
Definition
|
|
Term
| What Enterobacteriaceae is associated with "Current jelly" pneumonia, Alcoholics, and Nosocomial infections? |
|
Definition
|
|
Term
| What oppertunistic organism contaminates wounds and cause bacteremia and UTI in hospital patients? |
|
Definition
|
|
Term
| What Enterobacteriaceae have Brick-rd colonies? |
|
Definition
|
|
Term
| How does Urease produced by Proteus and Morganella promote UTIs? |
|
Definition
| raising pH of urine and potentiating formation of stones within which the organism may remain viable after apparently effective antibiotic therapy |
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