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Session 2 Microbio15

Microbio -15- GI #1 Infection Hartley

QuestionAnswer
What type of bacteria are the majority of GI pathogenic bacteria Gram Negative Bacteria
Why would you use MacConkey agar in a fecal culture it inhibits gram positive growth. And you get a color change based on lactose fermentation
Why would you use Hektoen Enteric Agar for a fecal culture it inhibits the growth of common colon flora and help selectively recover salmonella and shigella spp. if they are present and you have indicators to detect H2S production
Why would you use Campylobacter blood agar in a fecal culture agar enriched to recover campylobacter spp. from stool
Apart from a fecal culture what other tests can you run to differentiate what is causing the GI infection CBC with Diff. UA Stool Analysis (microscopic, fecal leukocytes, fecal lactoferrin(indicates neutrophils are present))
What antigen is found on the outer membrane of gram negative bacteria O-antigen
What Antigen is found on the flagella of gram negative bacteria H- antigen
When they have a capsule what type of antigen is found on gram negative bacteria K antigen
Why do we care what antigen is found on gram negative bacteria helps to characterize and identify the bacteria
What are the most common route of GI infection Fecal to oral route of contamination is most common also could be inadequately cleaned or cooked foods or water contaminated with fecal matter
What is the general progression of bacterial infections of the GI tract bacteria passes through the intestines -attaches to mucouse layer or intestinal epithelia -secret toxin -induce diarrhea and other symptoms -then hopefully cleared by host immune system
What are the general s/sx of GI infections Diarrhea, Cramps and Vomiting
What are some of the causes of acute diarrhea lasting less than 7-14 days drugs infectious agents feeding after a long fast fecal impaction
What is the tx for acute diarrhea monitor electroylytes and hydration and use fluid replacement therapy as needed also bismuth compound or anti-nausea meds can be offered as needed
Are there vaccines available for GI bacteria NO GALT(gut associated lymphoid tissue) will normally clear bacteria with innate immunity and IgA
Gram Negative Bacillus most strain rapidly ferment lactose and produce indole. Many strains are actually a normal GI flora so it can be hard to discriminate them from pathogenic strains E. Coli
What is significant of the following strains of E. Coli Enterotoxigenic E. coli (ETEC) Enteropathogenic E.coli (EPEC) Enterohemorrhagic E.coli (EHEC) Enteroinvasive E.coli (EIEC) Enteroaggregative E.coli (EAEC) They are pathogenic strains of E. Coli
What is the typical source of infection of Enterotoxigenic E. coli (ETEC) lack of good hygienic practices (ingesting contaminated food or water) Major Cause of Travelers Diarrhea
What is the major cause of traveler's diarrhea Enterotoxigenic E. coli (ETEC)
What is the progression of infection of Enterotoxigenic E. coli (ETEC) ETEC is ingested and attach to intestinal epithelia by pili in the small intestines -secretes one or both of two types of toxins causing symptoms -immune system clears infection after 3-4 days
what are the s/sx of infection with Enterotoxigenic E. coli (ETEC) WATERY Diarrhea, cramps, Vomiting, malaise, low grade fever More severe symptoms if ETEC secretes both types of toxins
in what age group are infections of Enterotoxigenic E. coli (ETEC) most common under 5 or over 15 yrs old
How do you differentiate ETEC from enterobacteria or plain E. Coli The toxins it secrets
What are the two toxins that Enterotoxigenic E. coli (ETEC) can secrete ST- small toxin LT- heat labile toxin (made of A and B subunits A pierces membrane B aids in membrane Binding)
what is the treatment with infection of Enterotoxigenic E. coli (ETEC) hydration as needed for symptoms only can give supportive care antibiotics will only shorten symptoms by 1 day. Although some physicians will take or prescribe antibiotics as prophylatic for traveling
How do you diagnose some one with an infection of Enterotoxigenic E. coli (ETEC) They will have Characteristic symptoms -watery diarrhea -abdominal cramping -low grade fever WITH ONLY lactose fermenting organisms on fecal cultures
what is the source of infection of Enteropathogenic E. coli, EPEC fecal oral contamination from poor hygienic practices. Adults are generally carriers and Infants get the disease
what is the progression of infection of Enteropathogenic E. coli, EPEC -EPEC is ingested and attaches to epithelial cells by pili in small intestines -Secretes factors that alter host cells -creates a pedestal for bacterial cell -induces diarrhea by loss of villi and lack of absorption -immune system clears the infectio
what are the s/sx of infection w/ Enteropathogenic E. coli, EPEC Fever vomiting WATERY diarrhea that may have large amounts of MUCUS Associated with clusters in the US
What E. Coli infection is associated with CLUSTERS in the US e.g. nursery and hospital outbreaks Enteropathogenic E. coli, EPEC
Enteropathogenic E. coli, EPEC are groupd with what type of pathogens Attachement and Effacement pathogens- all have a type III secretion system that is highly conserved
What are the stages of infection w/ Enteropathogenic E. coli, EPEC A- initial adherence B- Injection- type III secretion system C- Tight Adherence- Pedestal formation D- Diarrhea
What is the Type III secretion system like it is like a hypodermic needle at the cellular level and is the most complex bacterial secretion system
Since adults are carriers of Enteropathogenic E. coli, EPEC that means they don't develop a lasting immunity but since they don't have sympotms how are they dealing with the Enteropathogenic E. coli, EPEC likely have developed a resistance or tolerance to the bacteria
What is the tx for Enteropathogenic E. coli, EPEC infections hydration as needed antibiotics are generally not needed you can give bismuth compounds for symptomatic relief
What are the likely source of infection of Enterohemorrhagic E. coli, EHEC ingestion of insufficiently cleaned or cooked foods. Resevoir is usually adult cattle wich are asymptomatic
What is the progression of infection w/ Enterohemorrhagic E. coli, EHEC -EHEC are ingested and attach to epithelial cells via pili in the large intestines -Secrete factors that alter host cell -for a pedestal for the bacterial cell -secrete toxins that damage or kill host cells -immune system clears the infection
What are the s/sx of Enterohemorrhagic E. coli, EHEC infection !!! water diarrhea that progresses to BLOODY diarrhea -abdominal cramps -+/- fever -may also have hemolytic uremic syndrome
What is hemolytic uremic syndrome HUS toxin release into bloodstream lysis erythorcytes, thrombocytes and destroys glomerular capillary endothelial cells. can be fatal if kidney failure is not prevented
what is Enterohemorrhagic E. coli, EHEC O157:H7 most commonly associated with HUS hemolytic uremic syndrome
how is Enterohemorrhagic E. coli, EHEC similar to EPEC they both are A/E pathogens and carry a type III secretion system to induce pedestal formation
What is the mortality rate of patients w/ infection of Enterohemorrhagic E. coli, EHEC that develop HUS 3-17% 30% will have permanent disabilities (chronic renal insufficiency, hypertension, and neurological defects)
What are Enterohemorrhagic E. coli, EHEC toxins functionally similar to Shiga Toxin they have AB type toxins
what is the tx for Enterohemorrhagic E. coli, EHEC infection MONITOR for RENAL FAILURE hydration as needed antibiotics are usually not required
How can you tell your patient is infected w/ Enterohemorrhagic E. coli, EHEC cultures FAIL to ferment sorbitol (macConkey agar using sorbitol) Culture of O157 are sero positive -MUG assay EHEC typically don't produce Beta-Glucoronidase while 92% of other strains do
What are Enteroinvasive E. coli, EIEC biochemically, genetically and pathogenically related to Shigella Spp.
What are S. flexneri S. boydii S. sonnei S. dysenteriae Strains of Shigella Spp.
what are the sources of infection w/ Enteroinvasive E. coli, EIEC Fecal oral contamination contaminated food or water outbreaks reservoirs involve human sources
What is the progression of infection of Enteroinvasive E. coli, EIEC -EIEC is ingested and attach to large inetsine epith cells w/ pili -secret factor that induce uptake and transmission by M cells -Entry into the inf. or lat. sides of intest. epithelial cells -replication in epithelial cells -immune system clears inf
what are the s/sx of infection w/ Enteroinvasive E. coli, EIEC many are asymptomatic w/ transient fever early symptoms- fever, severe cramps, WATERY diarrhea late symptoms- reduced fever increased diarrhea with BLOOD, urgency, tenesmus
How are Shigella Dysenteriae type 1 different from Shigella Spp and EIEC IT secrets shiga toxin whil Shigella spp. and EIEC do not
What is the tx for Enteroinvasive E. coli, EIEC infection antibiotics in severe cases to decresae length of symptoms -hydration as needed (severe dehydration is possible)
How do you dx infection w/ Enteroinvasive E. coli, EIEC culture on differential and selective media (Hektoen enteric agar, MacConkey) DNA probes for EIEC are commercially available
What is the source of infection w/ Enteroaggregative E. coli, EAEC little is known. fecal to oral is likely also linked with foodborne outbreaks
what is the progression of infection w/ Enteroaggregative E. coli, EAEC =EAEC are ingested and attach to large intestin epithelia -Bacteria replicate and aggregate in a unique Stacked Brick fashion -secrete several toxins leading to inflammation and intestinal damage -immune system clears the infection
what are the s/sx of infection w/ Enteroaggregative E. coli, EAEC WATERY diarrhea (some cases may include blood or mucus in the feces) abdominal cramps EAEC may cause diarrhea for greater than 14 days especially in HIV patients and travelers.
What toxins does Enteroaggregative E. coli, EAEC secrete ShET1(shigella enterotoxin 1) similar to toxin in most shigella flexneri strains -- causes diarrhea w/ mechanism other than cAMP, cGMP or Ca2+ EAST1- similar to ETEC toxin ST PET- serine protease that alters enterocyte cytoskeleton
Why is there no vaccine against E. Coli many strains are non pathogenic and actually resident members of the normal GI flora
What is the TX for Enteroaggregative E. coli, EAEC antibiotics may be helpful for prolonged disease and give hydration as needed
What is the key in differential diagnosis between different strains of E coli. key differential is whether diarrhea contains blood or mucus
If the Diarrhea is WATERY what strains would you suspect EPEC, ETEC, most viral, (EAEC)
If the diarrhea is Bloody what strains would you suspect EHEC, Shigella spp./EIEC, (EAEC)
If the diarrhea is water + mucus what strain would you suspect EPEC
If your patient has recently traveled what cause of dirrhea would you suspect ETEC, EAEC, Rotavirus, EIEC
If your patient recently ate a meal of beef and now has Diarrhea what would be your suspected cause EHEC
If you patient has had diarrhea for the past 7 days what would you suspect EAEC, Shigella/EIEC, ETEC
Gram Positive Bacillus, Obligate Anaerobe readily forms spores Clostridium dificle
Where do you typically get an infection from clostridium dificle typically no socomial infection but can be community acquired as 3% of humans are normal carriers
What acounts for 30% of all antibiotic associated diarrheas Clostridium dificle
What is the progression of infection from clostridium dificle 1. Ingest contaminated food ( prior to or after antibiotic clearance of normal GI flora) 2. Colonization of gut and secretion of toxins 3. Extent of Ab production to toxin A determine outcome of infection
What are the s/sx of infectino with clostridium dififcle diarrhea may be mild and watery or be bloody -cramps -fever -leukocytosis -pseudomembranous colitis
What are the 3 toxins that clost. Dif. can secrete toxin A- Glucosyl Transferase targeting small GTPasees (Ras and Rho) Toxin B- similar to A but not enterotoxigenic Binary Toxin- ADP ribosylating enzyme targeting actin similar to C2 toxin and Iota Toxin
What are the antibiotics used to treat infection with C. Dificle Vanco, or Metronidazole
how do you dx infection w/ C. DIF Culture Gram Staining- is a gram pos bacillus Detection of Endospores
Gram Neg Bacillus that is not halophilic V. Cholera and V. Mimicus
Where do you typically get V. Cholera from lack of good hygenic practices ingesting contaminated water or food
What products have been associated with outbreaks of V. cholera Fish, Seafoods, milk, ice cream, and unpreserved meats
Why are infections with cholera associated with a high dose of the organism to cause infection V. Cholera is killed by acid so you need a lot to get past the stomach acid and cause infeciton
What is the progression of infection with V. Cholera 1. Cholera are ingested and attach to intestinal epithelia 2. Secretion of Toxin and assumption of sx 3. Immune system clears the infection
Does Cholera damage the enterocytes no
What are the associated s/sx of V. Cholera infection Severe Water Diarrhea Vomiting at onset Muscle Cramps due to dehydration
Are there any vaccines available for V. Cholera Yes oral vaccines available outside of US -live attenuated strain -killed vaccine + B subunit Vaccine
If you give immediate hydration therapy to a patient infected w/ V. Cholera what do you reduce to mortality risk to Reduces mortality risk to less than 1%
Gram Neg Bacillus that is curved, motile microaerophilic fastidious Campylobacter jejuni
What are the typical sources of infection from Campylobacter jejuni Direct contact with infected animals such as dogs, cats, birds indirect through eating contaminated water or milk or undercooked poultry associated w/ large outbreaks
What is the leading cause of bacterial gastroenteritis Campylobacter jejuni
What is the progression of infection w/ Campylobacter jejuni 1- C. Jejuni attaches to GI epithelium 2- Invades enetrocytes directly or passes through to lamina propria 3- Induces diarrhea uk method 4- immune system clears infection in 2-5 days
What are the s/sx of infection w/ Campylobacter jejuni abdominal Pain within 2-10 of infection cramps diarrhea- bloody fever chills Rarely any nausea or vomiting
What happens in .1% of infections w/ Campylobacter jejuni get Guillain-Barre syndrome esepcially HLA-B27 positive patients
what plays a role in providing immunity from Campylobacter jejuni Immunoglobulins give protective immunity
what is the tx for infection w/ Campylobacter jejuni fluid and electrolyte replacement
How do you dx infection w/ Campylobacter jejuni oxidase positive motile gram neg bacillus Culture on CAMPY-BAP Growth at 42C (inhibits growth of other enetrics) Microaerophilic
Gram Neg. Spirilum microaerophilic multiple sheathed flagella produces urease to create ammonia to neutralize stomach acids Helicobacter pylori
What is the progression of infection w/ H. Pylori 1- Ingest Bacteria which migrates through gastric mucus layer 2- Inflammation of epithelium and halt mucus production 3- thining of mucus layer leads to damage of epithelium by gastric secretions (ulcers) 4- infection may persist for years or life
What are the s/sx of infection w/ Helicobacter pylori Belching to vomiting epigastric pain/burning/gnawing (2-3 hours after meals) Relieved by eating, atacids, antisecretion agents Small% of infections lead to gastric cancer
How can you prevent infection w/ Helicobacter pylori no effective or proven method to prevent infection
What is the tx for H. Pylori combine antibiotics with antisecretory agents
How do you dx infection w/ h. pylori serology/ELISA it is difficult to culture
What is key in differnetiating which organism is causing infection with GI symptoms Get a Good H&P
Created by: Max Smith Max Smith on 2010-01-06



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