Presentation on theme: "Enterobacteriaceae Slackers Facts by Mike Ori. Disclaimer The information represents my understanding only so errors and omissions are probably rampant."— Presentation transcript:
Enterobacteriaceae Slackers Facts by Mike Ori
Disclaimer The information represents my understanding only so errors and omissions are probably rampant. It has not been vetted or reviewed by faculty. The source is our class notes. The document can mostly be used forward and backward. I tried to mark questionable stuff with (?). If you want it to look pretty, steal some crayons and go to town. Finally… If you’re a gunner, buck up and do your own work.
Rapidly growing large gram negative rods of various sizes that can grow on plain agar both aerobically or anaerobically.
Pili that mediates general attachment to a wide variety of epithelial cells via adhesins that interact with host D-mannose residues
E. Coli P pili characteristics
Pili that interact with digalactose (gal-gal) residues on uroepithelium thus allowing efficient colonization of the urinary tract.
E. coli colonizing factor antigen (CFA) or bundle forming pilin (BFP) characteristics
Pili that mediate attachment to enterocytes
E. Coli alpha hemolysin toxin
Pore forming exotoxin
Interferes with protein synthesis: An A-B toxin secreted by E. coli whose active unit interferes with protein synthesis by blocking the ribosomal amino acyl tRNA binding site. Causes hemolysis by unknown mechanisms. Interferes with kidney function: Circulating toxin binds renal tissues causing glomerular swelling and the deposition of fibrin and platelets into the microvasculature.
Cholera-like A-B toxin generated by some E. coli strains that increases cAMP production in host cells by ADP-ribosylation of Gas
Cholera-like (A-B?) toxin generated by some E. coli strains that increases cGMP production by host cells
Type 1 pili mediate binding in periurethral area. P pili mediate attachment to urogenital cells.
Watery diarrhea caused by labile/stable toxins with bacterial attachment facilitated by CFA (colony factor antigen) pili. All of the above are plasmid borne.
Significant cause of mortality in children 2 and younger in less developed countries. Common cause of traveler’s diarrhea. Human reservoir. Point to ponder: What kind of diarrhea would the time traveler’s wife’s husband have?
Bundle forming pili (BFP) bearing intimin protein mediate attachment of the cells to host enterocytes. Subsequent injection of E. coli secretion proteins (Esp) causes the formation of a pedestal by modifying the cytoskeleton.
Attachment and effacing lesion
Lesion caused by EPEC and EHEC E. coli strains by injection of E. coli secretory proteins (Esp) that results in the effacement of enterocyte microvilli and the attachment of E. coli at the top of pedestals formed from commandeered cytoskeletal components.
Whats the coolest thing about intimin
E. coli injects the receptor for intimin along with E. coli secretion proteins (Esp)
Common in less developed countries where it accounts for 20% of the diarrhea in bottle fed infants below 1 year of age.
Resembles EPEC in that it creates attaching and effacing lesions. Notably different however is its secretion of shiga toxin.
Bloody diarrhea and hemolytic uremic syndrome
More common in industrialized nations with industrialized meat packing practices. Outbreaks arise from undercooked meat and cross contamination of produce.
EHEC inoculating dose
EPEC EHEC differences
EHEC elaborates shiga toxin. EPEC prefers the small intestine EHEC prefers the colon
Virtually identical to shigella except that is has a lower incidence of person to person transmission. Likes silent brooding types, strong chins, and long walks on the beach.
Virtually restricted to children 5 or younger. Humans are the only known reservoir.
ETEC and EPEC disease course
Self limiting watery diarrhea that clears within a few days
Initial watery diarrhea lasting 1-2 days followed by intense abdominal pain and bloody diarrhea that resolves in 3-10 days.
Hemolytic uremic syndrome symptoms
Occurs in EHEC cases primarily in children < 10 years old. Oliguria, edema, and palor followed by hemolytic anemia, thrombocytopenia, and renal failure.
EHEC culture diagnosis
Does not ferment sorbitol. Grow out on MacConkey agar and then subject to O157 antisera.
Supportive care including hemodialysis and hemapheresis if HUS is present (hooray for h). Do not use abx or antimotility agents.
ExEC general guidelines
Supportive care is mainstay Replace fluids with oral rehydration therapy or IV if necessary. Abx for ETEC, EIEC, EPEC but NOT for EHEC Antimotility agents if you have to for EPEC and ETEC but NOT for EIEC of EHEC
Acid resistant (not acid fast) gram negative rod transmitted by person to person contact under conditions of poor sanitation which causes disease that begins with watery diarrhea and evolves into dysentery type diarrhea.
Shigella species and types
Four species (A-D). Group D has 38 antigenic types of O antigen
Spread by direct person to person contact under conditions of poor personal or community sanitation. Small infecting dose of less than 200 organisms insures efficient transmission. The reservoir is human
S dysenteriae epidemiology
Largely limited to underdeveloped nations with type 1 producing the most severe disease.
Shigella invasion target cells
Adherence to and transcytosis through M cells to reach underlying phagocytic cells.
Invasin protein antigen (Ipa) function
Proteins injected into host cells by shigella using a contact initiated injection system. These proteins have a wide range of function including cytoskeletal rearrangement, actin polymerization, and apoptosis
Shigella intracellular movement mechanism
Moves via actin polymerization of host actin filaments. Creates a characteristic actin “comet” tail.
What other bacteria invades in a manner similar to shigella
Listeria Why is shigella so popular at parties? Because its lysterical.
Shigella mucosal damage characteristic
Focal ulcers in the mucosa
Shigella diarrhea characteristics
Small volume stools containing WBC’s, RBC’s, and bacteria.
Shigella toxin elaboration characteristics
Not all strains elaborate shigella toxin but doing so correlates with disease severity. S dysenteriae type 1 elaborates Stx. If Stx is elaborated systemic effects of Stx can occur as can HUS.
Labs routinely screen for shigella. No other details were provided.
Generally self limiting however abx decrease duration of disease and the contagious period.
Shigella clinical triad
Cramps Tenesmus Frequent small volume, bloody, mucoid discharge
Gram negative facultative anaerobe with a wide range of serovars based on O,H,K typing. Disease for any given serovar may be restricted to humans, animals, or both.
Salmonella food poisoning characteristics
Picnics, warm summer days, drunken co- workers, contaminated food, logarithmic growth, You didn’t eat the potato salad did you? You did? Damn! 2 day incubation, 3-4 days of suffering. See you next year.
Salmonella inoculating dose
10000 or more
Salmonella outbreak epidemiology
Cross contamination from poultry, exotic pets, or humans particularly in the context of modern industrial food plants.
Salmonella infection path
Cellular transcytosis to invade lamina propria
Salmonella cytoskeletal rearrangement pattern
Ruffling occurs within minutes of contact. This results in pinocytosis of the bacterium.
Human only serovar of Salmonella
What is a common carrier organ for typhi?
Classic Victorian novel disease caused by typhi
Died of fever
Typhi disease cycle
Invasion of mucosa Ingestion by macrophages but escape of killing by interfering with oxidative burst/lysosome fusion (??) Travel to secondary lymphoid tissues Rupture of macrophages Dissemination of bacteria Dissemination of LPS endotoxin resulting in fever
Typhoid fever course
Resolution within about 3 weeks Or Death
Enteric fever cause
Disseminated Salmonella sites
Osteomyelitis of long bones Sepsis Biliary tree (typhoid Mary?)
Similar to shigella. Culture from blood early in enteric fever.
Salmonella gastroenteritis treatment
Supportive care Anti nausea and anti vomiting drugs Do not use abx as these prolong carrier state
Enteric fever treatment
TMP-SMX or other abx to which the strain is susceptible
Polysaccharide encapsulated enterobacteriaceae species that causes a classic lobar pneumonia.