with United States & Canada

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1 with United States & Canada COURSE DESCRIPTION In the United States, food poisoning is most often caused by the Salmonella bacterium. This type of food poisoning is also known as Salmonellosis. Most Salmonella infections result from people eating food or drink that is contaminated with Salmonella. This Continuing Education module will discuss an outbreak of food poisoning caused by handling contaminated pet treats as reported in the in the Morbidity and Mortality Weekly Report published by the Centers for Disease Control and Prevention. Prior to the presentation of the article, the module will discuss the use of the Gram stain to classify microorganisms and provide general information about Salmonella infections. Rev 2.0 April

2 COURSE TITLE: Human Salmonellosis Associated with Animal-Derived Pet Treats United States & Canada Author: Centers for Disease Control & Prevention and Lucia Johnson, MA, CLS(NCA), MT(ASCP)SBB Director of Continuing Education National Center for Competency Testing Number of Clock Hours Credit: 2.0 Course # P.A.C.E. Approved: Yes X No Upon completion of this continuing education module, the professional should be able to: 1. List the dyes included in the Gram stain. 2. Identify the appearance of Gram positive and Gram negative cocci and bacilli. 3. List commonly seen Gram positive and Gram negative cocci and bacilli. 4. Identify diseases caused by Salmonella bacteria. 5. List the antibiotics used to treat Salmonella infections. 6. State the disease most often caused by Salmonella infections in the United States. 7. List the symptoms of Salmonella infections. 8. Describe how Salmonella infections are transmitted. 9. Describe how Salmonellosis can be prevented. 10. Name the type (Serovar) of Salmonella identified in the pet treat cases as reported by MMWR. 11. State the type of specimen used to culture and identify the Salmonella in the three case studies discussed in the MMWR report. 12. Identify the locations of the two pet treat manufacturing plants identified as the source of the Salmonella contamination. 13. Identify the two types (i.e. animal sources) of pet treats found to be contaminated with Salmonella. 14. Describe techniques that could have been used by the pet treat manufacturers to assure the treats did not transmit bacteria. 15. List the populations of people that are at risk for serious illness caused by Salmonella. 16. Describe the recommendations made by CDC and the Public Health Agency of Canada to reduce the risk of Salmonella transmission to people from contaminated pet treats. Disclaimer The writers for NCCT continuing education courses attempt to provide factual information based on literature review and current professional practice. However, NCCT does not guarantee that the information contained in the continuing education courses is free from all errors and omissions. 2

3 INTRODUCTION TO MMWR ARTICLE IDENTIFICATION OF MICROORGANISMS USING THE GRAM STAIN The first step in identifying microorganisms, specifically bacteria and fungi, is to perform a Gram stain. The Gram stain, developed in 1882 by Hans Christian Gram is one of the most important staining techniques in microbiology. The stain consists of three dyescrystal violet, safranin, and iodine. Variations of the Gram stain technique exist where methylene blue is substituted for the crystal violet and basic fuchsin for the safranin. Microorganisms that appear purple in a microscopic examination are referred to as Gram positive. Microorganisms that appear pink-red are referred to as Gram negative. Some microorganisms do not specifically stain purple or pink-red and are referred to as Gram variable. The Gram stain also reveals the shape of the microorganism. Bacteria that are round are referred to as cocci, and those that are rectangular (rod-shaped) are referred to as bacilli. Although these two shapes are the most common, there are other shapes and many variations. The following chart classifies a few commonly seen microorganisms based upon their Gram stain results: Cocci (round) Bacilli (rod) Gram positive Staphylococcus, Streptococcus, Candida (yeast) Clostridium, Listeria, Lactobacillus Gram negative Neisseria Escherichia coli, Salmonella, Campylobacter Gram variable Mycobacterium tuberculosis, Bacillus, Nocardia NOTE: These photomicrographs are best viewed in color from the NCCT webpage or the Continuing Education CD-ROM. Photograph of Gram positive Staphylococcus aureus bacteria; the bacteria are the small round purple cells. The arrows point out some of the bacteria in clusters. Photograph courtesy of CDC/Dr. Richard Facklam 3

4 Gram positive Lactobacillus spp. bacilli; the bacteria are the purple rods appearing on top of and around a large vaginal squamous epithelial cell. Photograph courtesy of CDC/Dr. Mike Miller This Gram stained vaginal specimen reveals Gram negative Neisseria gonorrhoeae cocci inside a white blood cell, leading to a positive diagnosis of gonorrhea. (Note: The very small red dots are the bacteria.) Photograph courtesy of CDC/Brenda Novak Interpretation of Gram stains requires specific training and education. The federal government considers Gram stain interpretation to be a high complexity test and, as such, requires that only Clinical Laboratory Scientists interpret the test results. SALMONELLA BACTERIA The CDC report that follows on page 6 focuses on infections caused by Salmonella bacteria. Salmonella bacteria are Gram negative bacilli (rods). Over 2300 types or strains (known as Serovars) of Salmonella exist. One very important type of Salmonella is Salmonella Typhi, which causes typhoid fever. Typhoid fever is a life-threatening illness. In the United States, about 400 cases occur each year, and 75% of these are acquired while traveling internationally. Typhoid fever is still common in the developing world, where it affects about 21.5 million persons each year. Most Salmonella infections in the United States result in food poisoning. The following MMWR article discusses food poisoning caused by Salmonella Thompson. As a group, the food poisoning symptoms of Salmonella are diarrhea, fever, and abdominal cramps in humans. The disease is called Salmonellosis and the illness lasts from 4 to 7 days. Most persons recover from the illness but some infections may be so severe that the patient must be hospitalized. These serious infections result when the Salmonella 4 This photograph shows Gram negative Shigella bacilli in a stool sample from a patient with shigellosis, also known as dysentery. The arrow points out only a very few of the bacteria. The larger objects in the picture are red and white blood cells. Photograph courtesy of CDC

5 leaves the intestines, enters the blood stream, and then moves to other body sites. Individuals with serious infections may die unless they are treated promptly with antibiotics. Infants, the elderly, and those individuals with impaired immune systems are more likely to have severe forms of Salmonellosis. Salmonella live in the intestinal tract of humans and other animals, including birds. Salmonella is usually transmitted to humans by eating foods contaminated with animal feces. Contaminated foods look and smell normal and often include beef, poultry, milk, or eggs. However, all foods have the potential to be contaminated. Foods may also become contaminated by an infected food handler who neglected to wash his/her hands after using the bathroom. Thorough cooking destroys Salmonella. Salmonella infections are diagnosed in the laboratory by bacterial culture of the patient s feces and/or blood. To determine the best antibiotic to treat the disease, the laboratory performs antibiotic susceptibility testing. When Salmonella outbreaks occur, it is necessary to determine the actual strain that is causing the outbreak. This determination is made by a sophisticated laboratory analysis called Pulse Field Gel Electrophoresis (PFGE). This is a molecular biology technique separates the DNA of specimens to determine if the bacteria are identical in nature. The information provided by PFGE is used to evaluate outbreaks of Salmonella food poisoning. The specimen submitted for testing is the culture of the bacteria. Tips for preventing salmonellosis follow. Cook poultry, ground beef, and eggs thoroughly before eating. Do not eat or drink foods containing raw eggs, or raw unpasteurized milk. If you are served undercooked meat, poultry, or eggs in a restaurant, don t hesitate to send it back to the kitchen for further cooking. Wash hands, kitchen work surfaces, and utensils with soap and water immediately after they have been in contact with poultry. Be particularly careful with foods prepared for infants, the elderly, and the immunocompromised. Wash hands with soap and water after handling reptiles or birds, or after contact with pet feces. Avoid direct or even indirect contact between reptiles (turtles, iguanas, other lizards, snakes) and infants or immunocompromised persons. Don t work with raw poultry or meat, and an infant (e.g., feed, change diaper) at the same time. Salmonella infections often clear up within 5-7 days and do not require treatment. If the diarrhea is severe, an infected individual may need to be hospitalized and treated for dehydration. If the infection spreads outside of the intestines, antibiotics may be needed. Salmonella is treated with ampicillin, gentamicin, ciprofloxacin, or trimethoprim/sulfamethoxazole. Some strains of Salmonella have become resistant to routine antibiotics. NOTE: The following article was in the June 30, 2006/Vol.55/No.26 Morbidity and Mortality Report. The article was prepared by the Centers for Disease Control and Prevention (CDC) and was printed and distributed by the Massachusetts Medical Society, publishers of The New England Journal of Medicine. 5

6 Human Salmonellosis Associated with Animal-Derived Pet Treats United States and Canada During , contact with Salmonella-contaminated pet treats of beef and seafood origin resulted in nine culture-confirmed Salmonella Thompson infection in western Canada and the state of Washington. This is the third published report (1,2) of an outbreak of human illness associated with pet treats in North America and the first to describe such an outbreak in the United States. This report highlights the investigation of the outbreak by U.S. and Canadian pubic health officials and provides recommendations for reducing the risk that Salmonella-contaminated pet treats pose to humans. Public health practitioners should consider pet treats a potential source for Salmonella transmission. Case Reports Case 1. In February 2005, a man aged 26 years in Alberta, Canada, sought medical care because of diarrheal illness. Stool cultures yielded Salmonella Thompson (S. Thompson). The patient reportedly had fed his dog beef pet treats a few days before the onset of his illness. The dog was asymptomatic. A package of the same brand of pet treats fed to the dog was purchased and submitted for testing. The treats yielded S. Thompson, S. Cerro, and S. Meleagridis. The S. Thompson isolates from the patient were indistinguishable (i.e., defined as the outbreak strain) by pulsed-field gel electrophoresis (PFGE) using Xba1. The treats were packaged and distributed by a British Columbia (BC) manufacturing plant, but plant records were inadequate to determine where the treats had been produced. Case 2. In February 2005, a woman aged 37 years in BC sought medical care because of diarrheal illness. Stool culture yielded S. Thompson. The patient reportedly had fed her dog salmon pet treats a few days before the onset of her illness. The dog also had a diarrheal illness, but specimens were not collected. The remaining pet treats were collected from the patient s house for testing. The treats yielded S. Thompson. Isolates of S. Thompson from the patient and treats were indistinguishable from each other and from the outbreak strain by PFGE. The salmon treats originated from a Washington manufacturing plant. The treats were imported into Canada, labeled, and distributed for sale in BC and Alberta by the same BC manufacturing plant identified in case 1. Case 3. In March 2005, a woman aged 81 years in Washington sought medical care because of diarrheal illness, fever, and vomiting. The patient was hospitalized. Stool culture yielded S. Thompson indistinguishable from the outbreak strain by PFGE. The patient had purchased and fed beef pet treats to her dog before the onset of her illness. The patient reported frequent with her dog by reported no recent illness in the dog. The remaining treats were collected from the patient s house for testing. The treats yielded S. Thompson indistinguishable from the outbreak strain by PFGE. The treats originated from and were packaged by the Washington manufacturing plant that was the source of the treats in case 2. 6

7 Additional cases. In 2004 and 2005, six additional human cases of S. Thompson (three in BC, two in Washington, and one in Alberta), with isolates indistinguishable by PFGE from the outbreak strain, were identified by PulseNet USA and PulseNet Canada (National molecular subtyping networks for foodborne disease surveillance). Five of the six additional patients were interviewed. Three (60%) of them had handled pet treats from the Washington or BC manufacturing plants. The other two patients had pet dogs. Stool cultures from an asymptomatic dog yielded S. Thompson indistinguishable from the outbreak strain by PFGE. Source Investigation The BC and Washington manufacturing plants were investigated by authorities. Both manufacturers processed frozen, raw beef and salmon into pet treats for cats and dogs by thawing the materials, cutting them into the desired shapes and sizes, dehydrating them, and then packaging the finished products for distribution. The manufacturers in BC and Washington received frozen, raw beef parts from slaughterhouses in Canada and the United States, respectively. The Washington manufacturer also received frozen, raw salmon from a Washington seafood company. Although the pet treats were dehydrated at the BC and Washington plants, the dehydration temperatures were not high enough to kill bacteria that might have been present. No processing step, such as irradiation, that would destroy Salmonella and other bacteria was used during the processing. Production code dates, lot numbers, and location of plants were not recorded on the finished product packaging. No labels instructing pet owners to wash their hands after handling the product were provided. The BC manufacturing plant received some of its processed beef treats and all of its processed salmon treats from the Washington manufacturing plant. Cultures of salmon and beef pet treats manufactured at the Washington plant and collected at the BC plant by Canadian authorities, and cultures of salmon treats collected at the Washington plant by U.S. authorities, yielded S. Thompson indistinguishable by PFGE from the outbreak strain. The salmon treats contained up to 80,000 colony-forming units of Salmonella per gram. Pet treats from the BC and Washington plants also contained other Salmonella serotypes, including S. Montevideo, S. Newport, S. Give, S. Melearidis, S. Cerro, S. Muenster, S. Agona, and S. Anatum. Both manufacturing companies issued voluntary recalls of the implicated products in June Reported by: L Crowe, Calgary Health Region, Calgary; L Chui, PhD, Alberta Provincial Laboratory for Public Health (Microbiology); D Everett, Alberta Ministry of Health and Wellness. S. Brisdon, L Gustafson, MD, Fraser Health Authority, Surrey; E Galanis, MD, L McIntyre, L MacDougall, Msc, L Wilcott, A paccagnella, British Columbia Centre for Disease Control. D MacDonald, MHSSc, A Ellis, DVM, Public Health Agency of Canada. A Drake, MPH, J Koepsell, MS, C BeBolt, MPH, S McKeirnan, MPH, J Duchin, MD, Public Health Seattle & King County, Seattle; R Baer, MPH, M Leslie, DVM, Washington State Dept of Health. ML Collins, JM Johnson, DE Farmer, CE Keys, H Ekperigin, DVM, PhD, Food and Drug Admin. F Angulo, DWM, PhD, Div of Foodborne, Bacterial and Mycotic diseases, National Center for Zoonotic, Vector-Borne, and Enteric Diseases (proposed); RE Colindres, MD, EIS Officer, CDC. Editorial Note: In 2004, a total of 5,085 laboratory-confirmed cases of human Salmonella infections were reported in Canada, and 35, 661 laboratory-confirmed cases were reported in the United States (3,4). Studies in the United States have 7

8 demonstrated that for each laboratory-confirmed case of Salmonella infection, 38 Salmonella infections occur in the community, indicating that more than 1 million persons in Canada and the United States might be infected with Salmonella each year (5). Although salmonellosis generally is a self-limiting infection, it can result in serious illness in more vulnerable populations, such as the very young, older adults, and immunocompromised persons. Most human Salmonella infections are acquired by handling or consuming contaminated food products, particularly foods of animal origins. Infections also are acquired by direct and indirect contact with farm animals, reptiles, chicks, and, occasionally, pets. Infected animals usually shed Salmonella organisms in their feces. Humans can become infected when they place contaminated food, hands, or other objects in their mouths; therefore, handwashing after contact with animals is an effective way to prevent Salmonella infection. This report describes an outbreak of nine culture-confirmed cases of human S. Thompson associated with handling animal-derived pet treats in Washington and western Canada. Because laboratory-confirmed cases of Salmonella represent only a small proportion of cases in the community (5), this outbreak might have involved hundreds of infections. In recent years, an increasing variety of animal by-products, such as pig ears, have become available for purchase as animal-derived pet treats. Animal-derived pet treats have been associated with previous outbreaks of human Salmonella infection in Canada. In 1999, contaminated pig ear pet treats were confirmed as the source of an outbreak of human S. Infantis in several provinces (1,6). In 2002, contaminated pet treats imported from Texas were associated with human S. Newport infection in Calgary, Alberta (2). The S. Infantis isolates from the patients in Canada and from the pet treats in the United States were indistinguishable by PFGE. Follow up investigations of those outbreaks indicated that pet treats are frequently contaminated with Salmonella organisms. In Canada, after the 199 outbreak, Salmonella organisms were isolated from 48 (51%) of 94 samples of pig ear pet treats purchased from retail stores in Alberta (2). In the United States, Salmonella organisms, including S. Infantis, were isolated from 65 (41%) of 158 samples of pig ear and other animal-derived pet treats purchased from retail stores during (7). Detecting and controlling the transmission of Salmonella organisms through pet treats poses several challenges (8). Animal-derived pet treats often are contaminated with Salmonella, and the dehydration procedure used to make pet treats might not be effective at eliminating the organism. Aside from direct contact with contaminated pet treats, transmission of Salmonella to humans might also occur indirectly through infection in pets. Pets consuming contaminated treats might become unrecognized sources of contamination in the household. Young children, older adults, or immunocompromised persons in such households might have a higher risk for severe illness from Salmonella infection. In Canada, pet treats are not regulated, but the Canadian Food Inspection Agency has used the Animal Health Act* to encourage product recalls. The Public Health Agency of Canada and the Pet Industry Joint Advisory Council are collaborating to improve the safety of these products. *Available at 8

9 In the United States, pet treats are regulated by the Food and Drug Administration (FDA). Salmonella-contaminated pet treats are considered adulterated under the Federal Food, Drug, and Cosmetic (FDC) Act.** After the 1999 Canadian outbreak, FDA encouraged manufacturers to take voluntary steps to ensure the absence of Salmonella in pet treats. In addition, the American Pet Products Manufacturers Association published Guidelines for the Manufacturing of Natural Part Treats for Pets to educate its members about contamination risks (9). In 2004, FDA initiated annual nationwide testing of pet treats for Salmonella. Because results of this testing have shown that the prevalence of Salmonella organism in pet treats in the United States has not decreased, FDA plans to broaden its use of enforcement actions to ensure compliance with the FDC Act. Pet treat manufacturers, retailers, healthcare providers, public health authorities, veterinarians, and consumers should be aware of the potential for animal-derived illness in humans. Public health authorities should routinely consider this possibility during their investigations of cases or outbreaks of human Salmonellosis. In response to the public health hazard described in this and other reports, CDC and the Public Health Agency of Canada have issued recommendations (Box) to reduce the risk for transmission of Salmonella to humans from contaminated animal-derived pet treats. Box: Recommendations to reduce the risk for transmission of Salmonella organisms to humans from contaminated animal-derived pet treats. Persons should always wash their hands thoroughly with soap and water after handling animal-derived pet treats. Persons at increased risk for infection or serious complications of salmonellosis (e.g., children aged < 5 years, older adults, and immunocompromised persons) should avoid contact with animal-derived pet treats. Pet store owners, healthcare providers, veterinarians, and pet treat manufacturers should provide information to pet owners about the potential health risks of animal-derived pet treats and salmonellosis prevention. Pet treat manufacturers should implement a step (e.g., heat treatment or irradiation) that destroys Salmonella and other bacteria during the processing of pet treats and should provide labels containing production information. Sources: CDC and the Public Health Agency of Canada *Available at 9

10 References Laboratory Centre for Disease Control, Public Health Agency of Canada. Human health risk from exposure to natural dog treats. Can Commun Dis Rep 2000; 26:41-2. Pitout JDD, Reisbig MD, Mulvey M, et al. Association between handling of pet treats and infection with Salmonella enterica serotype Newport expressing the AmpC β-lactamase, CMY-2. J Clin Microbiol 2003; 39: Centre for Infectious Disease Prevention and Control. Notifiable Diseases Reporting System. Ottawa, Canada: Public Health Agency of Canada, Centre for Infectious Disease Prevention and Control; Available at CDC. Salmonella surveillance: annual summary, Atlanta, GA: US Department of Health and Human Services, CDC; Voetsch AC, Van Gilder TJ, Angulo FJ, et al. FoodNet estimate of the burden of illness caused by nontyphoidal Salmonella infections in the United States. Clin Infect Dis 2004; 38: S Clark C, Cunningham J, Ahmed R, et al. Chacterization of Salmonella associated with pig ear dog treats in Canada. J Clin Microbiol 2001; 39: White DG, Datta A, McDermott P, et al. Antimicrobial susceptibility and genetic relatedness of Salmonella serovars isolated from animal-derived dog treats in the USA. J Antimicro Chem 2003; 52:s Finlay R, Reid-Smith R, Weese JS. Human health implications of Salmonellacontaminated natural pet treats and raw pet food. Clin Infec Disease 2006; 42: American Pet Products Manufacturers Association, Inc. Guidelines for the manufacturing of natural part treats for pets. Greenwich, CT: American Pet Products Manufacturers Association, Inc; Available at 10

11 TEST QUESTIONS Human Salmonellosis Associated with Animal-Derived Pet Treats # Directions: Before taking this test, read the instructions on how to complete the answer sheets correctly. If taking the test online, log in to your User Account on the NCCT website Select the response that best completes each sentence or answers each question from the information presented in the module. If you are having difficulty answering a question, go to and select Forms/Documents. Then select CE Updates and Revisions to see if course content and/or a test questions have been revised. If you do not have access to the internet, call Customer Service at Which of these dyes can be substituted for safranin in one of the variations of the Gram stain? a. crystal violet b. iodine c. methylene blue d. basic fuchsin 2. Gram negative bacilli appear under the microscope as. a. pink-red rod-shaped cells b. round, pink-red cells c. purple rod-shaped cells d. round, purple cells 3. Which of these common bacteria stains as Gram negative cocci? a. Listeria b. Neisseria c. Campylobacter d. Streptococcus 4. Salmonella typhi can cause. a. typhoid fever b. food poisoning c. toxic shock syndrome d. botulism 5. If a Salmonella infection spreads outside the intestinal tract, which of these antibiotics could be used as treatment? a. ampicillin b. gentamicin c. ciprofloxacin d. all answers are correct 11

12 6. The disease most often caused by Salmonella in the United States is. a. typhoid fever b. food poisoning c. toxic shock syndrome d. botulism 7. Salmonella Thompson infections are characterized by which of these symptoms? a. diarrhea b. fever c. abdominal cramps d. all answers are correct 8. Salmonella is usually transmitted to humans by eating foods that. a. are contaminated with animal feces b. look normal c. smell normal d. all answers are correct 9. Which of these is not a tip for preventing salmonellosis? a. Cook poultry, ground beef, and eggs thoroughly before eating. b. Eat foods containing raw eggs or unpasteurized milk. c. Wash hands well after handling reptiles or birds. d. Keep reptiles away from people with compromised immune systems. 10. Which of these is the type (Serovar) of Salmonella identified in the pet treat cases reported in the MMWR article? a. typhi b. Cerro c. Thompson d. Meleagridis 11. What type of specimen was used to culture and identify the Salmonella found in the three cases discussed in the MMWR report? a. skin scraping b. stool sample c. blood d. throat swab 12

13 12. The two pet treat manufacturing plants that were identified as the sources of the Salmonella contamination in the MMWR article were located in. a. Washington and British Columbia b. Alberta and British Columbia c. Oregon and Washington d. Vancouver and British Columbia 13. The pet treats contaminated with Salmonella were made of. a. beef and pork b. beef and salmon c. shark and salmon d. turkey and beef 14. If the two pet treat manufacturing plants had processed their products, they could have destroyed the Salmonella. a. using antibacterial soap b. using code dates and lot numbers c. with irradiation d. with instructions about hand washing 15. Which of these people might be at risk for serious illness caused by Salmonella? a. People with HIV or AIDS b. Infants or the elderly c. People with impaired immunity d. All answers are correct 16. Which of these is not one of the recommendations to reduce the risk for transmission of Salmonella organisms from contaminated animal-derived pet treats, as provided by the Public Health Agency of Canada and the CDC? a. After giving pets animal derived treats, wash your hands. b. Refrain from giving your pets treats of any kind, as you cannot be sure. c. Children (<5) should avoid contact with animal derived treats. d. Pet treat manufacturers should use treatments to destroy the bacteria during processing. *End of Test* 13