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38 Cards in this Set
- Front
- Back
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Two Examples of NON inflammatory enteric infections
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V. cholerae
Enterotoxigenic E. coli |
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Two examples of inflammatory enteric infections
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Shigella
Samonella |
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Example of penettating enteric infections
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Salmonella typhi
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Is vibrio cholera suspetible to gastic acid?
Does it require high inoculum ? Is is seen in areas of poor sanitation? |
YES YES YES
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Do vibrio produce
A-B toxin? B-C toxin? C-D toxin? |
AB Toxin
Leads to hypersecretion |
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Do V cholera use pili
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YEs Vibs use pili
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Organism causes a spectrum of illness from asymptomatic colonization → mild diarrhea → severe diarrhea
Onset of illness is abrupt Stools described as “rice-water” Mortality rate 60% in untreated severe disease |
Cholera
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Dehydration
Loss of bicarbonate and metabolic acidosis Hypokalemia Hypotension Heart arrythmias Renal failure |
Cholera
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Cause of diarreha in young children living in or traveling to developing coutries
Containminates food water |
ETEC
Enterotoxigenic E. coli |
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What produce 2 classes of toxins
Heat-labile toxin (LT) Heat stabile toxin (ST) Ability to adhere to GI tract also important in infection |
ETEC
Enterotoxigenic E. coli |
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Cramps and watery diarrhea predominant symptoms
Illness milder than cholera |
ETEC
Enterotoxigenic E. coli |
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Heat Labile Toxin of ETEC
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Similar to cholera toxin
LT Increases cAMP levels Increased secretion of fluid and electrolytes Prostaglandin and cytokines are increased resulting in further fluid loss |
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Heat-Stabile Toxin of ETEC
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Binds to guanylate cyclase
Results in increased cGMP Causes increased fluid secretion |
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Name the bug
Small, comma-shaped Gram-negative bacilli Grow best in microaerophilic environment with increased CO2 C. jejuni grows best at 42 degrees C Most common cause of bacterial diarrhea identified in US case: A 75 year old female presents to the ED with a two day history of diarrhea, crampy abdominal pain, vomiting and a fever to 102. She has no recent travel history. She ate at a picnic about 4 days earlier. |
Campylobacter
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The antibodies against which bug is associated with Guillain Barre
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Campylobacter
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What's a major souce of Campylobacter
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poultry, milk
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how to treat camp infection
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replace flids and electrolytes
antibiotics |
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Name the BUG
Gram-negative facultative organism Over 2500 serotypes based on O antigen rhymes with -nella |
Salmonella
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Organism invades and replicates in Peyer’s patches and enterocytes
Organism surrounded by membrane where it replicates Inflammation results to limit spread of infection Organism may be released into blood or lymphatic system |
Salmonella
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_______ and ________-
are strict human pathogens Passed person to person Asymptomatic carriage occurs |
S. typhi and S. paratyphi
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Gastroenteritis
Nausea, vomiting, nonbloody diarrhea Fever, abdominal cramping, myalgias, headache Bacteremia may result Children, elderly, AIDS patients at most risk |
Salmonella
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Initially nonbloody diarrhea, abdominal pain
Can progress to bloody diarrhea Resolves spontaneously HUS may result as complication Renal failure, thrombocytopenia, microangiopathic hemolytic anemia Can result in death |
Enterohemorrhagic E. coli
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Makes Shiga Toxin
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Enterohemorrhagic E. coli
It binds to Gi and Kidney cells Disrupts Protein synthesis Stimulates production of inflammatory cytokines |
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EHEC Sources
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Meat (beef), unpasteurized milk or juices
Person to person Petting zoos Country fairs Swimming |
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Gram-negative facultative anaerobe
Four species S. sonnei (developed countries) S. flexneri (developing countries) S. dysenteriae (most severe) S. boydii (least common) |
Shigella
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Illness seen in
Children (daycare) Male homosexuals Household contacts Residents of custodial institutions Fecal-oral route predominates Fewer than 200 bacilli cause disease Antibiotics may limit spread |
Shigella
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Adherence
Proteins secreted into epithelial cells Engulfment of bacteria Intracellular replication Cell to cell spread |
Shigella
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Induce apoptosis
Polymorphonuclear leukocytes attracted to tissue and breakdown GI tract integrity Shiga toxin produced by S. dysenteriae |
Shigella
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Abdominal cramps
Diarrhea Fever Bloody stools Pus in stools HUS may result (hemolytic uremic syndrome) |
Clinical Manifestations
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A 6 year old child returns from visiting India with her parents. She presents to her pediatrician with fever, chills, abdominal pain, headache, and myalgias of 3 days duration. Her parents remember that she had a few loose stools several days before her fevers were noticed but now she is constipated.
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Typhoid Fever
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S. typhi and some other Salmonella strains pass through cells lining the intestines and are engulfed by macrophages
Organisms replicate in liver, spleen, bone marrow Severe systemic illness results Followed by GI symptoms corresponding to colonization of gall bladder and reinfection of intestinal tract |
Typhoid Pathogenesis
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Complications such as intestinal perforation can occur
Secondary to hyperplasia, ulceration, necrosis lymphoid tissue |
Typhoid Fever
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A 42 year old female with a history of asthma and diabetes was hospitalized for pneumonia. She responded rapidly to her antibiotic therapy. She returned one week following her discharge with profuse diarrhea, fever to 101 and an elevated white blood cell count of 14,000.
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Clostridium difficile
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Produces 2 toxins
Enterotoxin (toxin A) Cytotoxin (toxin B) Cytotoxin B appears to be most important in pathogenesis More virulent strain isolated recently Increased toxin production |
Clostridium difficile
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Culture
Cytotoxin detection in tissue culture Immunoassays to detect toxin Rapid PCR methods have been developed |
Diagnosis
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Stop offending antibiotic if possible
Metronidazole or vancomycin Relapse can occur because spores not killed by antibiotic treatment |
Clostridium difficile
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Enteric illness caused by bacteria can be categorized as noninflammatory, inflammatory and penetrating although clinically there may be considerable overlap in the way patients present with their illness.
The epidemiologic history is very important when a clinician sees a patient with suspected bacterial diarrhea |
Summary
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What can cause C Dif
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Use of ABs that wipe out normal flora
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