IDMM Week 1 PBL Flashcards
List the viruses that cause enteric infections
Rotavirus
Enteric adenovirus
Norwalk virus
What type of enteric infection do viruses cause
self limited infectious diarrhea
Transmission of rotavirus
children under 6
contaminated water
fecal oral
Pathogenic features of rotavirus
destroy mature epithelial cells in the middle and upper villi–watery diarrhea is due to MALABSORPTION
transmission of enteric adenovirus
young children and infants
sporadic
Pathogenic features of enteric adenovirus
self limited infectious diarrhea
Norwalk virus transmission
young and old
fecal oral
Pathogenic features of norwalk virus
epidemic gastroenteritus with diarrhea, nausea, vomiting
List bacteria that cause enteric infections
enterotoxigenic E. Coli Campylobacter jejuni Yersinia enterocolita Shigella Enteropathogenic E. coli Salmonella C. Difficile Vibrio cholerae
Transmission of ETEC
travellers diarrhea
food and water borne
pathogenic features of ETEC
watery diarrhea
heat labile toxin activates AC–>increases concentration of cAMP
heat stable toxin increases [cGMP]–>resultsin reduced Na+ absorption in villus cells and increased CL- secretion in crypt cells
Transmission of campylobacter jejuni
mainly kids
contaminated food and water
zoonotic
Pathogenic features from campylobacter jejuni
gastritis, enterocolitis, septicemia
causes BLOODY diarrhea and FEVER
cholera-like toxins, invasion (leading to inflammation), translocation into lamina propria and mesenteric lymph nodes
Guillain-barre syndrome
Yersinia enterocolita transmission
mainly kids
contaminated food and water
Yersinia enterocolita pathogenic features
- RUQ pain
- BLOODY, mucoid diarrhea
- pseudoappendicities, mesenteric adenitis syndrome (Peyer’s patches)
- arthritis, ERYTHEMA NODOSUM
HA enterotixin–like E. Coli: invasion into intestinal wall, regional lymph nodes and blood
16-72 hour incubation
Shigella transmission
fecal oral
contaminated food and water
Shigella pathogenic featuers
- DYSENTERY
- invasion, SHIGA TOXIN (causes hemorrhage, inhibits protein synthesis), actin rockets for cell-cell invasion
Enteropathogenic E. Coli transmission
children–nursery school outbreaks
Enteropathogenic E. Coli pathogenic features
- watery diarrhea
- initial binding is by bundle-forming pilus
- binding activates phospholipase C trhough Hp-90–>increase IP3 and Ca2+ which causes actin polymerization immediately beneath the organism–>effacement of microvilli
- intimate contact is mediated by a number of proteins )intimin)
- organism sits on the flat pedestal created by the altered cytoskeleton
- change in cell architecture causes direct damage, excess water, leading to diarrhea
- attaching and effacing lesions
salmonella transmission
food and water borne
human and animal reservoirs
salmonella pathogenic features
S. typhi - typhoid fever (including intestinal bleeding)
Gastroenteritis
sepsis
C. difficile transmission
hospital acquired
antibiotic associated
C. difficile pathogenic features
pseudomembrane
enterotoxin–disrupts membrane integrity
cytotoxin–cells lose filaments and lyse
NON INVASIVE
Vibrio cholerae transmission
pandemic
epidemic
vibrio cholerae pathogenic features
severe watery diarrhea due to cholera toxin
parasites associated with enteric infections
giardia lamblia
entamoeba histolytica
transmission of giardia
travellers diarrhea
contaminated drinking water
pathogenic features of giardia
NO enterotoxins
NO invasion
IgA proteases, sucker disc to adhere
cause diarrhea due to MALABSORPTION
FROTHY, FATTY stool
transmission of entamoeba histolytica
large reservoir of asymptomatic carriers
fecal oral
sexual transmission (anal)
contaminated food and water
entamoeba histolytica pathogenic features
- BLOODY diarrhea
- FEVER
- intestinal pain
attach to colonic epithelium, lyse colonic epithelial cells, invade bowel wall
contain cysteine proteases, channel forming protein for BORING HOLES into plasma membranes
Methods for parasite detection
special formalin preparation
O&P
what tests do you need special requests for?
O&P
viruses
non-routine bacteria (i.e C. diff and shiga toxin)
Do you use gram staining in most GI infection diagnosis?
No because already a large amount of bacteria in GI under normal circumstances
Why might antibiotics be contraindicated in some enteric infections?
they may lyse the bacteria and release large amounts of endotoxin or exotoxin which exacerbates the symptoms ie with EHEC
Which enteric infections are indicated for antibiotics?
Shigellosis
Typhoid fever
Cholera
List infection control measures to prevent the spread of enteric pathogens to others
- adequate hand washing
- proper disposal of fecal matter
- maintain a clean water supply
- stay at home if sick
- dont share foodstuffs
- dont share dishware and eating utensils
- wash and cook foodstuffs thoroughly
- proper transport and storage of food
Public health measures taken against food-borne illness
- food safe education program
- ongoing surveillance programs
- mandatory reporting programs (shigella, e. coli, listeria, clostridium botulinum, salmonella)
What is the public health investigation that follows the outbreak of a food-borne illess
- initial assessment–ID causative agent, investigate its source
- risk assessment–determine resources required
- public notices–recall product if necessary–prevent future outbreak
- post-outbreak education and establishment of new guidelines if required
