BY:JULIA BURTON

MARIA CHIAFFARANO

Nothing Worse than Tainted Ham!

Background Information

Local Festival was held in Palm Beach County90 people became ill

Symptoms: nausea, vomiting, diarrhea

17 victims sought medical attention Most cured within 24 hours

It’s thought that the origin of the infection was from ham sold at the festival

The Affected System

Digestive System is made up of the Espohagus Liver Small intestine Large intestine Gallbladder Pancreas Rectum

Our Job

Given a culture from one of the 17 patients Identify the cause of the outbreak Identify antibiotics that may be used to treat the

infection if necessary

Possible Causes

Escherichia coliPseudomonas aeruginosaSalmonella entericaStaphylococcus aureus Streptococcus pyogenesHaemophilus influenzae

Possible Cures

Antibiotics Penicillin Tetracycline Chloramphenicol Streptomycin Vancomycin Gentamycin

Procedure

Gram Stain provided the cultureCulture organism on selective/ differential

mediaAntimicrobial susceptibility test

Gram Stain

Information: Gram positive stains (using MSA agar) and Gram

negative stains (using MacConkey agar)

What we chose: Gram positive plate (Mannitol salt agar or MSA plate)

Gram Stain

Why? Helps to differentiate the two distinct bacterial

species (negative and positive) Faster than bacterial culture approach Significant in identifying a working diagnosis of

certain disease conditions

Gram Negative

Doesn’t react to crystal violet Stains pinkish-redCan be decolorized in accepting safranin

(counter stain) Uses MacConkey Agar

Differential plating medium used in detection and isolate of all types of dysenter

Used (generally) to differentiate strains of salmanella Colonies of bacteria are brick red in color

Gram Positive

Reacts with crystal violet dye (stains dark purple)

Unique cell wall (composed of several peptidoglycan layers, multilayered, thick)

Presence of techoic acids Lacks lipopolysaccaride content, peryplasmic

space and outer membrane (makes it low in lipoprotein and lipid composition)

Release exotoxins Uses MSA agar

MSA Agar

Selective and differential mediumHigh concentration of salt selects for

members of the staph bacteria since they can tolerate high saline levels

Contains sugar mannitol and pH indicator phenol red

Acidic byproduct is formed which causes the phenol red to turn yellow

Selective Differential Media

We chose the MSA plate because it is used for gram positive bacteria

Throughout our testing, we discovered that our bacteria was gram positive and would only grow on the MSA plate

Results: The Staphylococcus aureus grew at a fast rate, the

E.coli did not grow at all (it is gram negative), and the patient’s bacteria did not grow either However, due to technical difficulties, the patient’s

bacteria was supposed to grow, therefore giving a positive result for Staph

Staphylococcus aureus

Gram positive spherical bacteria Occur in microscopic clusters

Cells divide successively in three perpendicular planes

Fermentation of glucose produces mainly lactic acid

Ferments mannitol Golden yellow colony on agar

Antimicrobial Susceptibility Test

Information: Gram positive bacteria are easier to treat (with

antibiotic) than gram negative bacteria This is because gram positive bacteria lacks a membrane

whereas gram negative bacteria contain two membranes which regulate what goes in and out of the cell

Procedure: For the lab, we put the patient’s bacteria on a plate

along with six different types of antibiotics to see which antibiotic would be most effective to cure the patient

Results

Antibiotics used: Penicillin 32 mm diameter - Sensitive

Tetracycline - 24 mm diameter- Sensitive

Chloramphenicol- 19 mm diameter- Sensitive

Streptomycin- 12 mm diameter- Resistant

Vancomycin- 13 mm diameter- Sensitive

Gentamycin- 23 mm diameter- Sensitive

Results (cont.)

These results told us that the bacteria was sensitive to most of the antibiotics (gram positive bacteria) Most sensitive to Penicillin Resistant to Streptomycin