Gastrointestinal Organisms Flashcards by Bryan Edwards

Physical characteristics of enterobacteriaceae?

Facultatively anaerobic

G- Rods

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Enterobacteriaceae use what type of secretion system?

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What antigens are used to type Enterobacteriaceae.

O, H, K/Vi

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Biochemical tests for Enterobacteriaceae?

IMViC
Carbohydrate fermentation
Packaged Test Kits

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What does IMViC stand for?

Indole methyl red Voges-Poskauer citrate

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How are carbohydrate fermentations occur?

Use MacConkey’s Agar (Lactose)

Lac+ are coliforms

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Name for packaged test kits for Enterobacteriaceae?

Enterotube

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Three most common causes of foodbourne outbreaks?

Salmonella
Campylobacter
Shigella

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Relationship of Enterobacteriaceae to endocrine system

Gut bacteria can respond to stress-induced neuroendocrine hormone levels

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How do bacteria avoid immune response?

Subvert response to avoid detection

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How can E. Coli be detected on agar?

Copious acid production detected by green metallic sheen on EMB agar

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Three general clinical syndromes that come from E. Coli

Enteric/Diarrheal Disease
Urinary Tract Infections
Sepsis/Meningitis

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Most common extraintestinal E. Coli infections?

UTI via UPEC

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Two ways that E. coli may lead to UTI

Acquire from proximity of anus to urethral meatus

From increased sexual activity (honeymoon cystitis)

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UPEC is associated with the __ Pilus

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What does EPEC stand for?

What does it do?

Enteropathogenic
Intimin attached protein, bundle formed pili
Efface small intestine microvilli and inhibit water uptake

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Medical effects of EPEC?

Who gets it?

Watery, self-limiting diarrhea

Esp. Young Children

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What does ETEC stand for? Nickname?

Medical side effects?

Enterotoxigenic. “Traveler’s Diarrhea”

Watery diarrhea, increased gut motility, ab cramps

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ETEC is associated with what pili?

CFA adhesion pili for brush-border membrane

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What toxins are produced by ETEC?

2 LT Toxins (LT1 like cholera, higher cAMP)

2 ST toxins (activates cGMP)

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What does EHEC stand for?

Medical side effects?

Enterohemorrhagic
Bloody diarrhea without fever
Hemolytic-Uremic Syndrome

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How does EHEC mediate medical effects?

Verotoxin (Shiga-like) – AB toxin protein synthesis inbititor

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What is Hemolytic-Uremic Syndrome?

Treatment?

Uremia and organ failure due to glomerular damage

NO anti-biotics – they induce stx gene

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What is EIEC?

Medical effects?

Enteroinvasive

Bloody fever with fever

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EIEC is Indistinguishable from...

Shigella dysenteriae type I

Factors produced by EIEC?

Invasive colonization factors

What is EAEC? | Medical Effects?

Enteroaggregative | Noninflamatory pediatric diarrhea caused by biofilm development

E. coli K1 is a major cause of...

neonatal meningitis

Why is E. coli K1 not a good antibody target?

Molecular mimic of host NCAM receptors

Who is E. coli K1 especially dangerous to?

low birthweight infants

Salmonella grows on what medium?

Selective media with bile salts (deoxycholate)

How is salmonella classified?

By serotype (O, H, Vi(K))

All salmonella belong to what species?

S. enterica

It is important to distinguish what two categories of salmonella enterica?

S. typhi and paratyphi vs. all others

Three types of disease caused by salmonella enterica?

Typhoid Fever Bacteremia/Septicemia Enterocolitis/Gastroenteritis

Typhoid Fever is cause by what forms of salmonella?

S. Typhi or Paratyphi

Medical effects of Typhoid Fever?

Invasive disease - reaches bloodstream through mucosa Disseminates via macrophage to spleen, liver, GB Death from intestinal hemorrhage

Who gets bacteremia/septicemia from Salmonella?

Immunocompromised Patients

Medical effects of salmonella enterocolitis/gastroenteritis?

Nausea, Vomiting, Diarrhea, Fever Common | May colonize GB and shed for weeks

In what food products is Salmonella enterocolitis/gastroenteritis spread?

Eggs and Poultry Products

Four ways in which salmonella enterocolitis/gastroenteritis is spread?

Fecally contaminated water Endemic in Eggs/Poultry Crops fertilized by excreta From Pets

Describe pathogenesis of salmonella.

Binds brush border to invade gut epithelil cells Invade deep tissues/bloodstream Produce cytotoxic enterotoxin

Type of toxin? Effect of components?

A2B5 A1 -- ADP-ribosylates G-protein A2 -- damages DNA and halts cell replication

Shigella can also grow in _____ by ______

Bile Efflux pumps and DNA repair Uses Phospholipids as a C-source

Shigella grows on ____ agar

S-S

Clinical presentation of shigella?

Onset with Acute Watery Diarrhea 2 days later - blood and mucus into stool Subsides in about a week, but lethal dehydration

How is Shigella spread?

Infection via fecal-oral route

Shigella is most common in what population?

Children

How is Shigella spread?

4 Fs | Food, Fingers, Feces, Flies

Explain the pathogenesis of shigella.

- Phagocytosed and transmitted through M cells - Engulfed by macrophages in lamina propria - Lyse phagolysosome and replicate in cyto - Macro apop. -- release IL1 and cytos that make junctions permeable - Induces basal membrane phagocytosis

How does shigella spread?

Actin tails

How does shigella secrete invasion factors?

Type III secretions

How does Shiga enterotoxin kill?

Disruption of protein synthesis

Unique staining seen in yersinia?

Bipolar staining (Wright-Giemsa, Wayson's)

How does Yersnia bind?

YadA

Yersnia uses what secretion system? | What antigens allow intracellular growth?

Type III | V and W antigens

Yersnia pestis is most commonly known as...

plague

Three types of yersnia pestis?

Bubonic Septicemic Pneumonic

Symptoms of Bubonic yersnia pestis?

1-8 day incubation Malaise, headache, vomiting Painful Buboes in groin and other lymph nodes

What are buboes full of? | What diseases with buboes must yersnia be distinguished from?

Bacteria and Pus | Tularemia, Pasturella

Describe septicemic yersnia pestis

Primary or secondary to bubonic | Sepsis, Purpura, DIC, Necrosis

Describe pneumonic yersnia pestis?

Primary or Secondary Primary form inhalation, secondary from intravascular dissemination Hemoptysis, bilateral alveolar involvement

Outlook for pneumonic yersnia pestis

Virtually 100% fatal within 24 hours

How is yersnia pestis spread?

Zoonosis Typically spread by vector (rat flea) Reservoirs are Deermice and ground squirrels

How does yersnia pestis effect fleas?

Toxin blocks flea's gut, forms blood clot | When flea bites again, clot is regurgitated into host

Aside from natural transmission, yersnia pestis can be seen as...

A Warfare Agent

Pathogenesis of yersnia pestis?

- Type III Secretory System injects toxins - Inhibits MAP kinase signalling pathway (YopJ) - No cytokine production, no cell replication - Inhibits Phagocytosis (YopE) - Inhibits Platelet Aggregation (YopM)

How is yersnia pestis controlled?

Insectiside to kill fleas | Vaccine that must be boosted every 6-12 months

How do you treat a yersnia patient treated?

Oral tetracycline for exposed and asymptomatic I.M. Streptomycin once symptoms Pneumonic plague treatment is rarely successful

Symptoms with Y. enterocolitica

- - Enterocolitis with intestinal abscess -- bloody diarrhea, abdominal cramps, fever - - Mesenteric adenitis

Reservoirs for Y. enterocolitica?

Cattles, Hogs

How is Y. enterocolitica spread?

Feces, Contaminated drinking water/milk

How are Y. enterocolitica and Y. pseudotuberculosis treated?

Ampicillin | Ceph III, SxT

Describe klebsiella pneumonia medical effects.

Small Percent of Pneumonias | Extensively hemorrhagic and necrotizing (currant jelly sputum)

Treatment success of klebsiella pneumonia?

50-100% fatal

Describe the pathogenesis of klebsiella granulomatis

Granuloma inguinale | Mimics syphilis

Describe sores in klebsiella granulomatis.

Painless anal or genital sores | Gradually progressive lesions destroy large areas of tissue

How is proteus mirabilis seen on agar?

Swarming motility

Proteus mirabilis is associated with what condition?

UTI

Proteus miribilis causes what condition? How?

Bladder Stones | Urease production

How is Serratia marcescens usually acquired? | Common symptoms?

Opportunistic Infection | Pneumonia, Bacteremia, Endocarditis

How are enterobacteria usually treated, generally?

Isolate and clean sources | Ampicillin, Cephalosporins, Quinolines, Sulfa

For a uncomplicated UTI, Don't use_______. 1st choice -- 2nd choice --

Don't -- Flouroquinolone 1st -- Bactrim (SxT) 2nd -- Fosfomycin

Why don't you want to use f'quinolones for UTI?

It mimics a quorom sensing signal, can lead to film formation

Typically you would treat Traveller's Diarrhea with ____ | You would treat campylobacter with _____

Rifaximin | Azithromycin

There has recently been increased appreciation for the importance of restoring normal _______ in GI disorders

Mucus Production

Action of MUC2

Subdues dendritic cell inflammatory response via Treg activation

Gastrointestinal Organisms Flashcards

(87 cards)