The Presence of Foodborne Pathogens on Public Surfaces

1
The Presence of Foodborne Pathogens on Public
Surfaces

• Jennifer L. Stanley
• Gabrielle F. Clodomir

2
Background

• Pathogenic microorganisms found normally in
  healthy animals used for food can contaminate
  these products and be passed on to humans.
• Many bacteria have been found to survive from
  hours to weeks on non-porous surfaces and
  inanimate objects have been found to play a role
  in the transmission of human pathogens (Reynolds
  et al. 2005). Extremely pathogenic strains of E.
  coli have been found to survive on stainless
  steel, a common surface material, for up to 28
  days (Wilks et al., 2005).
• The potential for contamination of public
  surfaces at the University of Maryland is great.
  Hundreds if not thousands of people may come in
  contact with a single door handle in a single
  day. Foodborne pathogens have the potential to
  spread in dining halls and other areas where food
  is prepared and/or eaten.

3
Background

• The presence of S. aureus, Salmonella, and E.
  coli on several public surfaces was tested.
• door handle, table top, and fork from a
  University of Maryland dining hall
• keyboard and toilet lever found in the
  Microbiology building, and a personal cell phone.
  
• It was projected that the common food-borne
  pathogens Escherichia coli, Salmonella, and
  Staphylococcus aureus will be found on these
  surfaces, indicating that stricter precautions
  must be followed to prevent contamination of
  these surfaces and to prevent transmission of
  these organisms to humans.

4
Protocol

• A door handle, table, and fork from the South
  Campus Dining Hall, a keyboard and toilet lever
  in the Microbiology building, and a personal cell
  phone were tested for the presence of three
  bacterial organisms.
• Two samples were taken from the same location on
  each surface. A third sample was taken after the
  use of a disinfectant (Clorox Disinfecting Wipes)
  on the location.
• Selective media was used to determine the
  presence of S. aureus, Salmonella, and E.coli
  each sample. The spread plate technique was used.
  Samples were plated on TSA as well.
• MacConkey media E. coli
• Bismuth Sulfite Salmonella
• Chapman Agar S. aureus

5
Protocol

• A sterile cotton swab was dipped in saline
  solution and used to collect each sample.
• The surface was swiped once with the cotton swab
  and placed in a sterile container.
• A second sample was taken with a new sterile
  cotton swab at the exact same location as the
  first sample.
• A third sample was taken using Clorox
  Disinfecting Wipes to clean the surface prior to
  collection of the sample.
• Each swabs was dipped in a tube containing 1 mL
  of saline and vortexed. .1 ML of each sample was
  plated onto one TSA, MacConkey, Bismuth Sulfite,
  and Chapman media plate.
• All plates were incubated for 48 hours at 37
  degrees Celsius (MacConkey, Bismuth Sulfite, TSA)
  and 30 degrees Celsius (Chapman)
• After 48 hours, results were observed.

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ResultsDoor handle

• The TSA plate contained two types of white
  colored colonies.
• No growth was found on the MacConkey, Bismuth
  Sulfite, or Chapman Agar plates.

Sample 1 on TSA
7
ResultsFork

• Two types of colonies were found on the TSA
  Plates.
• No growth was found on the MacConkey, Bismuth
  Sulfite, or Chapman Agar plates.

Sample 1 on TSA
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ResultsTable

• Sample 1 of the TSA plate contained yellow
  colonies. Sample 3 contained several different
  types of colonies.
• No growth was found on the MacConkey, Chapman,
  and Bismuth Sulfite Agar plates.

TSA Sample 1
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ResultsKeyboard
This section of the experiment was repeated after
observing excessive growth on sample 3 plates.

• First Set of Samples
• The TSA plate for sample one yield several yellow
  and white colonies. Sample 2 and the control
  contained a potential mold contaminant.
• The Chapman plate for sample 2 contained several
  colonies. The sample 3 plate contained many
  yellow and white colonies.
• The first set of samples taken produced no colony
  growth on MacConkey or Bismuth Sulfite plates.

• Second Set of Samples
• The TSA plates for samples 1 and 2 contained
  several small colonies
• The sample 1 Chapman agar plate contained several
  yellow colonies.
• No colonies were found on any of the sample 3
  plates.
• The second set of samples also produced no growth
  on the MacConkey and Bismuth Sulfite plates, with
  the exception of a very small white colony on the
  Sample 1 MacConkey plate.

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ResultsKeyboard
TSA Plate Control Sample Set 1
TSA Plate Sample 2 Sample Set 2
11
ResultsCell Phone

• The TSA plate for Sample 2 contained large yellow
  colonies.
• No growth was found on the MacConkey, Bismuth
  Sulfite, or Chapman Agar plates

Sample 2 on TSA
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ResultsToilet

• No growth was found on any of the plates for the
  toilet samples.

Sample 1 on TSA
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DiscussionStaphylococcus aureus

• Gram-positive, nonmotile, nonspore-forming
  facultative anaerobe
• in pairs, short chains, or bunched, grape-like
  clusters
• Common bacterium found on skin and in the nose of
  25 of healthy people
• Produces seven different toxins that are
  responsible for food poisoning
• Most commonly food contaminated by food workers
  who carry the bacteria or through contaminated
  milk
• Staphylococci exist in air, dust, sewage, water,
  milk, and food or on food equipment,
  environmental surfaces, humans, and animals
• Presence indicates poor sanitation
• Staphylococcal toxins could be used as a
  biological agent either by contamination of
  food/water or by aerosolization and inhalation.
  Breathing in low doses of staphylococcal
  enterotoxin B may cause fever, cough, difficulty
  breathing, headache, and some vomiting and
  nausea. High doses of the toxin have a much more
  serious effect

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Staphylococcal food poisoning

• true incidence of staphylococcal food poisoning
  is unknown because of poor responses from victims
  during interviews with health officials
  misdiagnosis, inadequate collection of samples
  for laboratory analyses improper laboratory
  examination not contagious
• Disease Process Gastrointestinal illness-via
  preformed enterotoxins
• Symptoms fast acting, sometimes causing illness
  in as little as 30 minutes, symptoms usually
  develop within one to six hours. Patients
  typically experience several of the following
  nausea, vomiting, stomach cramps, and diarrhea.
• Treatment rest, plenty of fluids, and medicines
  to calm their stomachs antibiotics not effective
  against enterotoxins Recovery after 1-3 days
• Prevention wash hands and under fingernails
  vigorously with soap and water before handling
  and preparing food, keep kitchens and
  food-serving areas clean and sanitized, food is
  to be stored longer than two hours, keep hot
  foods hot (over 140F) and cold foods cold (40F
  or under)

15
Salmonella

• Salmonella serotype Typhimurium and Salmonella
  serotype Enteritidis are the most common in the
  United States
• gram negative
• rod-shaped, motile bacterium -- nonmotile
  exceptions S. gallinarum and S. pullorum,
  nonsporeforming
• Onset time -- 6-48 hours.
• Infective dose -- As few as 15-20 cells depends
  upon age and health of host, and strain
  differences among the members of the genus.
• estimated that from 2 to 4 million cases of
  salmonellosis occur in the U.S. annually 40,000
  cases of salmonellosis are reported in the United
  States

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Salmonellosis

• Disease Process Infection of the intestines
• Symptoms Acute symptoms -- Nausea, vomiting,
  abdominal cramps, minal diarrhea, fever, and
  headache. Chronic consequences -- arthritic
  symptoms may follow 3-4 weeks after onset of
  acute symptoms
• Treatment usually resolve in 5-7 days and often
  do not require treatment unless the patient
  becomes severely dehydrated or the infection
  spreads from the intestines. Antibiotics are not
  usually necessary unless the infection spreads
  from the intestines, then it can be treated with
  ampicillin, gentamicin, trimethoprim/sulfamethoxaz
  ole, or ciprofloxacin.
• Prevention Poultry and meat, including
  hamburgers, should be well-cooked. Avoid
  consumption raw or unpasteurized milk or other
  dairy products. Produce should be thoroughly
  washed before consuming People should wash their
  hands after contact with animal feces

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E. coli

• Facultative gram negative rod
• An estimated 73,000 cases of infection and 61
  deaths occur in the United States each year
• E. coli is a normal inhabitant of the intestines
  of all animals and humans. When aerobic culture
  methods are used, E. coli is the dominant species
  found in feces.
• Normally E. coli serves a useful function in the
  body by suppressing the growth of harmful
  bacterial species and by synthesizing appreciable
  amounts of vitamins. A minority of E. coli
  strains are capable of causing human illness by
  several different mechanisms.
• E. coli serotype O157H7- rare variety of E. coli
  that produces large quantities of one or more
  related, potent toxins that cause severe damage
  to the lining of the intestine emerging cause of
  foodborne illness

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E. coli O157H7 Hemorrhagic colitis

• Most illness has been associated with eating
  undercooked, contaminated ground beef.
  Person-to-person contact is also an important
  mode of transmission
• Disease process organism can be found on a small
  number of cattle farms and can live in the
  intestines of healthy cattle Bacteria in
  diarrheal stools of infected persons can be
  passed from one person to another if hygiene or
  handwashing habits are inadequate.
• Symptoms severe bloody diarrhea and abdominal
  cramps sometimes the infection causes no
  symptoms. Usually little or no fever is present.
• Treatment Most persons recover without
  antibiotics or other specific treatment in 5-10
  days. There is no evidence that antibiotics
  improve the course of disease, treatment with
  some antibiotics may precipitate kidney
  complications
• Prevention Cook all ground beef and hamburger
  thoroughly. Wash hands, counters, and utensils
  with hot soapy water after they touch raw meat.
  Persons with diarrhea should wash their hands
  carefully with soap, and that persons wash hands
  after changing soiled diapers. Anyone with a
  diarrheal illness should avoid swimming in public
  pools or lakes, sharing baths with others, and
  preparing food for others.

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DiscussionComments

• More research and adjustment of sample 3
  procedures.
• The results indicate that, while some potential
  pathogens may be present on public surfaces, the
  danger perceived by the public is often
  exaggerated.
• This project reinforces the importance of basic
  hygiene and cleaning methods in dining areas and
  home surfaces.

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References

• Center for Food Safety and Applied Nutrition,
  FDA. http//www.cfsan.fda.gov/list.html
• Foodborne Illness, CDC. http//www.cdc.gov/ncido
  d/dbmd/diseaseinfo/foodborneinfections_g.htm
• Reynolds, Kelly A et al. Occurrence of bacteria
  and biochemical markers on public surfaces.
  International Journal of Environmental Health
  Research. Jun 2005.
• Wilks, S. A. et al. The survival of Escherichia
  coli O157 on a range of metal surfaces.
  International Journal of Food Microbiology. Dec
  2005.