Gastrointestinal Organisms Flashcards
Physical characteristics of enterobacteriaceae?
Facultatively anaerobic
G- Rods
Enterobacteriaceae use what type of secretion system?
3
What antigens are used to type Enterobacteriaceae.
O, H, K/Vi
Biochemical tests for Enterobacteriaceae?
IMViC
Carbohydrate fermentation
Packaged Test Kits
What does IMViC stand for?
Indole methyl red Voges-Poskauer citrate
How are carbohydrate fermentations occur?
Use MacConkey’s Agar (Lactose)
Lac+ are coliforms
Name for packaged test kits for Enterobacteriaceae?
Enterotube
Three most common causes of foodbourne outbreaks?
Salmonella
Campylobacter
Shigella
Relationship of Enterobacteriaceae to endocrine system
Gut bacteria can respond to stress-induced neuroendocrine hormone levels
How do bacteria avoid immune response?
Subvert response to avoid detection
How can E. Coli be detected on agar?
Copious acid production detected by green metallic sheen on EMB agar
Three general clinical syndromes that come from E. Coli
Enteric/Diarrheal Disease
Urinary Tract Infections
Sepsis/Meningitis
Most common extraintestinal E. Coli infections?
UTI via UPEC
Two ways that E. coli may lead to UTI
Acquire from proximity of anus to urethral meatus
From increased sexual activity (honeymoon cystitis)
UPEC is associated with the __ Pilus
P
What does EPEC stand for?
What does it do?
Enteropathogenic
Intimin attached protein, bundle formed pili
Efface small intestine microvilli and inhibit water uptake
Medical effects of EPEC?
Who gets it?
Watery, self-limiting diarrhea
Esp. Young Children
What does ETEC stand for? Nickname?
Medical side effects?
Enterotoxigenic. “Traveler’s Diarrhea”
Watery diarrhea, increased gut motility, ab cramps
ETEC is associated with what pili?
CFA adhesion pili for brush-border membrane
What toxins are produced by ETEC?
2 LT Toxins (LT1 like cholera, higher cAMP)
2 ST toxins (activates cGMP)
What does EHEC stand for?
Medical side effects?
Enterohemorrhagic
Bloody diarrhea without fever
Hemolytic-Uremic Syndrome
How does EHEC mediate medical effects?
Verotoxin (Shiga-like) – AB toxin protein synthesis inbititor
What is Hemolytic-Uremic Syndrome?
Treatment?
Uremia and organ failure due to glomerular damage
NO anti-biotics – they induce stx gene
What is EIEC?
Medical effects?
Enteroinvasive
Bloody fever with fever
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
