case study 1: peanut butter is tainted
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TRANSCRIPT
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Case Study 1: Peanut Butter is TaintedSuma and Kathryn
+Background Information
425 people from 44 states were ill Diarrhea, fever, abdominal cramps
Illness usually lasted 4-7 days, some cases of diarrhea were so severe patient needed to be hospitalized Out of 351, 71 (20%) were hospitalized No deaths
Onset dates ranged from August 1st to February 16th, and 67% of cases occurred after December 1st
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Affected System
Digestive system
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Parts that could be affected- Stomach
- Small intestine
- Large intestine
+Patient PB
Stomach cramping
Diarrhea
Moderately high temperature
16 hours prior to onset, peanut butter sandwich had been consumed
Escherichia coli
Pseudomonas aeuroginosa
Salmonella enetrica
Staphylococcus aureus
Streptococcus pyogenes
Haemophilus influenzae
Symptoms and History Possible Culprits
+Gram stain
Add bacteria sample, E.coli (negative control), and S. aureus (positive control) to individual drops of water Let dry Heat fix slide
Cover smears with crystal violet dye for one minute, then rinse with DI water
Repeat with Gram’s iodine, but rinse with decolorizer acetone alcohol
Repeat with safranin, rinse with DI water
Blot dry, view using oil immersion
Procedure
+Results (Gram stain)
Patient sample (1000x)
E. Coli (1000x)
Pink- Gram negative
Purple- Gram positive
Eliminate S. aureus and S. pyogenus
S. aureus (1000x)
Expected results What do these results mean?
+Selective/differential plate
Use MacConkey Agar because patient sample is gram negative
Spread E. coli (positive control), S. aureus (negative control), and patient sample in a V-formation on the plate
Incubate
Procedure
+Results (selective/differential)
Reddish pink- lac positve, gram negative
Whitish clear- lac negative, gram negative
No growth- gram positive
E. coli- pinkish red
S. aureus – no growth
Patient- whitish clear
Expected Results
What do these results mean?
■ eliminate E. coli
+Antimicrobial Susceptibility Test
Coat a plate with a thin film of bacteria, making sure not to miss any spots
Place six antibiotic discs around the edges of the plate, evenly spaced apart Tetracyclin Penicillin Streptomycin Vancomycin Gentamicin Chloramphenicol
Allow bacteria to incubate
Measure zone of no growth
Compare to known values to find sensitivity/resistance
Procedure
+Results (Antimicrobial Susceptibility)
Patient sample is: Resistant to penicillin,
vancomycin Intermediate to
streptomycin, gentamicin Sensitive to tetracyclin,
chloramphenicol
Tetracyclin = 20 mm (S)
Penicillin = 16 mm (R)
Streptomycin = 14 mm (I)
Vancomycin = NA (R)
Gentamicin = 14 mm (I)
Chloramphenicol = 22 (S)
Eliminate P. aeuroginosa Resistant to chloramphenicol
Eliminate H. influenzae Different symptoms
(meningitis)
What do these results mean?
+ Salmonella enterica
A rod shaped, flagellated, Gram negative bacteria
+Salmonella enterica
Arranged in a cluster- tetrad form
Anaerobic- can live with low oxygen conditions
Affects gastrointestinal region, through the fecal oral route
Injects a protein called SipA to enter cell
Disturbs the membrane, causes levels of free calcium to rise and disorganizes cytoplasm
+Epidemiology
Causes diarrhea, fever, vomiting, abdominal cramps
Can spread from intestine to blood stream, cause bacteremia
raw meat, eggs (can be found on any food surface)
Normal bacterial flora in reptiles and amphibians
contaminated water or soil
Single most common cause of food poisoning in the US Salmonellosis
Salmonellosis can be prevented by Cooking food
thoroughly Washing hands and
cooking surfaces refrigeration