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.

6. The TSA plate contained two types of white colored colonies. No growth was found on the MacConkey, Bismuth Sulfite, or Chapman Agar plates. ResultsDoor handle Sample 1 on TSA

7. Two types of colonies were found on the TSA Plates. No growth was found on the MacConkey, Bismuth Sulfite, or Chapman Agar plates. ResultsFork Sample 1 on TSA

8. 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. ResultsTable TSA Sample 1

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

10. ResultsKeyboard TSA Plate Control Sample Set 1 TSA Plate Sample 2 Sample Set 2

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

12. ResultsToilet • No growth was found on any of the plates for the toilet samples. Sample 1 on TSA

13. 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

14. 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 140°F) and cold foods cold (40°F 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

16. 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/sulfamethoxazole, 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

17. 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 O157:H7- 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

18. E. coli O157:H7: 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.

19. 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.

20. References • “Center for Food Safety and Applied Nutrition”, FDA. http://www.cfsan.fda.gov/list.html • “Foodborne Illness”, CDC. http://www.cdc.gov/ncidod/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.