2. Debriefing
67 cases in NJ, NY, PA, DE, and SC
Bloody diarrhea and severe abdominal cramps
of 67, 51 hospitalized and 8 kidney failures (hemolytic-uremic
syndrome)
November 20 - December 5
Peak in the last week of November
Had all eaten at a Taco Bell
Chopped yellow onions tested positive for a pathogen; DNA
fingerprinting confirms onions were not source of the infection
14. First Elimination
Escherichia coli (Gram-) Rod Shaped
Pseudomonas aeruginosa (Gram-) Rod Shaped
Salmonella enterica (Gram-) Rod Shaped
Staphylococcus aureus (Gram+) Spherical
Streptococcus pyogenes (Gram+)Spherical
Haemophilus influenzae (Gram-) Rod Shaped
15. Selective/Differential
Media
MacConkey Agar
Salt bile is selective aspect
Lactic acid is differential aspect
Grows Gram- bacteria and stains for lactose fermentation
Lac+ CO2, acid, and alcohol
agar will become a bright pink/red color when lactose is
fermented because the acid lowers the pH
Lac- cannot ferment the lactose
colorless
Gram+ can’t ferment lactose because the bile salts do not
allow for them to grow, therefore not allowing them to ferment
the lactose
17. Second Elimination
Escherichia coli (Gram-) Rod Shaped (Lac +)
Pseudomonas aeruginosa (Gram-) Rod Shaped
(Lac-)
Salmonella enterica (Gram-) Rod Shaped (Lac-)
Haemophilus influenzae (Gram-) Rod Shaped
(Lac +)
18. Escherichia coli or
Haemophilus
Haemophilus
influenzae?
Escherichia coli influenzae
Can cause: Can cause:
Food poisoning Bacteremia
Diarrhea Pneumonia
Gastroenteritis Acute Bacterial
Meningitis
Urinary Tract
Infection
Usually in kids
19. It’s… E. coli!!
Gram –
Rod shaped
Generally aerobic
Most strains are opportunistic pathogens
Capsulated and Non-Capsulated
20. Cell Wall/Shape/
Arrangement
Outer membrane of cell wall is lipopolysaccharide that functions
as endotoxin
can lead to inflammation, high fever, hypotension, capillary damage,
intravascular coagulation, tissue degradation, and irreversible shock
Some pili let bacterium adhere to epithelial cells of the mucous
membranes
Some cell wall adhesions let bacterium make more intimate
contact with the mucous membranes
Some strains secrete enterotoxins that cause the loss of sodium
ions and water from the small intestines watery diarrhea
Some strains secrete a toxin that kills epithelial cells of the large
intestines bloody diarrhea
22. Location in Nature
Lower intestine of warm-blooded organisms
Can be found in:
Unpasteurized milk and apple cider
Ham, turkey, chicken, roast beef, sandwich meats
Raw vegetables, cheese
Contaminated water
27. Antimicrobial
Susceptibility Test
E. Coli (mm) Staph (mm)
Gentamycin 21 (S) 10 (R)
Penicillin 0 (R) 27 (R)
Vancomycin 0 (R) 12 (S)
Chloramphenicol 25 (S) 17 (I)
Streptomycin 13 (I) 12 (I)
Tetracycline 22 (S) 19 (S)
28. Tetracycline
Generally used in fighting infections of urinary tract
and intestines
Protein Synthesis Inhibitor
Kills bacterial cells by inhibiting their translation
Binds to 30S ribosomal subunit
Prevents tRNA from binding to ribosome
29. Conclusion
Patients ingested raw or undercooked meat with E.
coli from Taco Bell
Caused an infection
Tetracycline is the best antibiotic to give them
Will halt the protein synthesis in the E. coli