The salmonella bacteria

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Bacteria are ubiquitous; they may be good or bad for the host, affecting them in a positive manner or in negative disease causing ways. Infections that are caused by the bacteria Salmonella are zoonotic, meaning they can be spread from humans to animals or animals to humans (Wikipedia, 2010). Salmonella can also be easily transferred through the foods we eat and is one of the major causes of food-borne illness. Salmonella does not necessarily infect a host to kill them but to survive and multiply. The uncomfortable and/or painful symptoms of Salmonella, diarrhea, stomach cramps, and high fever, can usually last anywhere from a couple days to a full week (Lite, 2009). Approximately 1.4 million people are infected with Salmonella in the United States alone each year (Swanson, 2007). It is easy to hypothesize that since Salmonella is spread from animals to humans and vice versa, pets are a probable carrier for this bacterial disease and can, without difficulty, increase the likelihood of it being spread to humans (Swanson, 2007).

In August 2004, isolates of Salmonella were acquired from eight different hamsters at an unidentified pet supplier in Minnesota. Professionals were put to work to determine if the recently detected human cases of infections with Salmonella were in any way linked to the same strain found in these rodent carriers. The eight hamsters were brought to the University of Minnesota Veterinary Diagnostic Laboratory where tissue samples from the ill hamsters were cultured. Using electrophoresis the diagnostic laboratory was able to confirm the isolates as S. enterica serotype Typhimurium (Swanson, 2007). A serotype is a group of closely related microorganisms distinguished by a common set of antigens (, 2010). There are over 2,300 serotypes for the family Salmonella (, 2006). The pulsed-field gel electrophoresis (PFGE) pattern of the isolates of the hamsters represents only 23 of 17,737 S. enterica serotype Typhimurium isolates collected since 1998, therefore proved relatively uncommon (Swanson, 2007). By using electrophoresis to separate the proteins and analyze them, the laboratory could figure out the specific strain of Salmonella these rodents had. Knowing the specific strain can prove very useful in finding out if these ill, infected rodents were the cause of recently infected humans.

During June 2004, a young boy with symptoms of Salmonella infection was admitted to a hospital for five days. The boy's stool culture proved he had the same S. enterica serotype Thyphimurium infection as the eight hamsters from the Minnesota distributor. His family had purchased a hamster from a pet supplier approximately a week before the boy started having symptoms of this infection. The hamster died as soon as the boy started having serious symptoms (Swanson, 2007).

In August 2004, a stool sample was taken from another young boy who had intense symptoms of Salmonella infection for almost fourteen days. After being cultured the sample proved the boy was infected with the same uncommon strain as the hamsters from the pet distributor. After culturing the mouse's lungs and other body parts, it was proven the pet mouse the boy and his family had purchased was infected with S. enterica serotype Typhimurium. The mouse had died only a week after being bought by the family (Swanson, 2007). For the numerous amounts of pet stores that exist and amount of pets bought from them, it seems infections of Salmonella and other bacterial diseases would occur even more often than here or elsewhere reported. As stated previously, bacteria are ubiquitous and found everywhere imaginable. Having that said, it is probable that most infections caused by pets are not as serious as Salmonella infections and go unreported or are less relevant to the public's knowledge.

 ““““As a result of the Salmonella outbreak from the Minnesota pet distributor, the Center for Disease Control and Prevention (CDC) and the U.S. Department of Agriculture investigated the trail. They used interviews with the infected patients or the patient's parents to trace back and find the origination of pet distributors and breeders who sold the infected pets (Swanson, 2007). Tracing back the outbreak, with the help of patient interviews, was the main method used to configure a chart of results. It was found that twenty-eight isolates from the humans infected were identified as S. enterica serotype Typhimurium. Of twenty-two patients who made themselves available for an interview, thirteen of them had contact with a rodent that was bought from a pet store. Two of the patients were infected with Salmonella by secondary transmission and seven patients had no recollection of being exposed to rodents. With the help of one urine specimen and twenty-seven stool samples they were able to configure these numbers (Swanson, 2007).

Traceback Results for Pet Rodents Associated with an Outbreak of Multidrug-Resistant S. enterica Serotype Typhimurium

Swanson et al. 356 (1): 21, Figure 1; January 4, 2007

The chart above shows the trail of different distributors and breeders who carried rodents with Salmonella infections and the locations of the humans who became ill and the specific date. The breeders, distributors, and patient's location are all abbreviated by state. For example, IL - 1 and IL - 2 were interviewed and it was discovered they both purchased an ill hamster from an Illinois pet store. By tracing back from one person to the next, they found out who the Illinois pet store received the hamster from which happened to be an Arkansas distributor, who purchased it from an Arkansas breeder, which they received from an Iowa Distributor. For this type of study, tracing from the patients who were infected by rodents back to where the rodents originated seems like the most logical and organized way to find the source of the outbreak, how many people it affected, and put the scattered pieces together.

“““““Since not all cases are always reported, detected, or easily traced in a large national outbreak, it is likely that there were more infections than were claimed or discovered. In conclusion, medical professionals should consider more widely pet rodents as a potential cause of Salmonella infections (Swanson, 2007). Not only should medical professionals consider rodents as a potential cause of Salmonella infections, but everyone should. Not only the public but the pet distributors as well, after all, this entire outbreak began with them. Pet distributors and breeders should take better care of the pets they receive by making sure they are healthy and not be making a profit off of selling infectious pets to the public.

“““““As shown from the previous examples, we now know how easily Salmonella can be transmitted from animals to humans; but how easily is it transmitted through the food we consume and who is likely at risk of infection? The Food and Agricultural Organization of the United Nations and the World Health Organization (WHO) decided that S. enterica was one of the biggest concerns when considering powdered infant formula (PIF). There have been somewhat recent, large outbreaks of PIF tainted with S. enterica, even when the PIF that was being consumed met all of its specifics on the set of international standards (Cahill, 2007). It's hard to even comprehend that after meeting highly specific standards set on an international level there are still large outbreaks of different types of bacterial infections, like Salmonella, that occur rather frequently. Strictly considering only infants, 121.6 laboratory confirmed infections of Salmonella occurred per every 100,000 infants, which were stated to be eight times greater than among any other age group that had been infected (Cahill, 2007). This is a scary fact to consider especially for mothers who do not or can not breast feed either by choice or possible health concerns.

“““““PIF is not a sterile product. Where you store PIF, how you prepare it, and how you feed it to your child, can give extensive opportunity for bacterial growth causing it to be unsafe for consumption. Giving bacteria this opportunity can increase the PIF from possible low levels of bacterial contamination to a higher level of risk (Cahill, 2007). The public should be more aware of the possibility of PIF contamination and learn the importance of proper storage and how to prepare PIF in a sanitary manner. The levels of Salmonella in PIF are often extremely low so it frequently goes undetected in the formula. As an example, an outbreak of Salmonella infection in infants led to investigation and bacteriological sampling by thirty-three laboratories and found zero pathogens in 4,554 samples on 658 batches of PIF. After this sampling that showed there were no signs of contamination of PIF with Salmonella, a laboratory found Salmonella in an open packet of PIF from the home of an infant who had been recently infected. They decided to do more investigation on packets of PIF that had the same manufacturing identification number as the open contaminated packet found in the infants home and discovered traces of Salmonella in 4 of the 267 packets (Cahill, 2007).

A great amount of cases of Salmonella from PIF are likely to go unreported. These outbreaks of Salmonella from PIF make us, an international community, recognize that something needs to be done and proper precautions need to be taken (Cahill, 2007). Not everyone that has a child, especially new, young mothers, realize some of the important or necessary precautions that need to be taken when caring for a child. There needs to be more direct information on PIF preparation and storage given to parents who decide to formula feed their children, especially for new parents. The people manufacturing PIF products need to have more stringent regulations on what is considered feasible for children and what could be potentially harmful and cause bacterial infection.

In 2008, 1,407 people in forty-three states, Canada, and the District of Columbia, were diagnosed with Salmonella serotype Saintpaul enteritis. Two-hundred and eighty-two of the infected humans were sent to the hospital and two of the older patients that were admitted later died. The Centers for Disease Control and Prevention (CDC) believed it was tomatoes from the southwest that were the cause of the Salmonella outbreak but there was not any evidence to prove this. Months later, they found that jalapeno and serrano peppers from one individual Mexican farm were accountable for the entire outbreak of Salmonella (Maki, 2009). It is interesting to think all it takes is one bad batch of crops from one lone farm to cause such a large number of Salmonella infections and in such widespread geographical locations.

U.S. farmers have been making gradual progress in taking precautionary measures to reduce contamination of their crops but no matter what, there is still a possibility that they become contaminated because bacteria are everywhere. There needs to be more effective ways for monitoring the manufacturing of food that ensures food is safe for consumers (Maki, 2009).

When Salmonella infections occur they are most likely not to be fatal. Just like any bacteria, Salmonella could be anywhere. It is important to always take proper precaution when preparing food, infant formula, or even buying a new pet. Of course there is not much you as an individual can do to prevent these sporadic nation-wide outbreaks of Salmonella but you can try to help prevent yourself from becoming infected. Do not eat undercooked meats, poultry, eggs, or any other food item and always wash your hands thoroughly after handling them, as for these are all possible places Salmonella could be hiding.

Works Cited

Swanson, Stephen J., Cynthia Snider, Christopher R. Braden, David Boxrud, Arno Wunschmann, Jo Ann Rudroff, Jana Lockett, and Kirk E. Smith. “Multidrug-Resistant Salmonella Enterica Serotype Typhimurium Associated with Pet Rodents.” Multidrug-Resistant Salmonella Enterica Serotype Typhimurium Associated with Pet Rodents 356 (2007): 21-28. The New England Journal of Medicine. 4 Jan. 2007. Web. 30 Mar. 2010. <>.

Cahill, Sarah M., Kaye Wachsmuth, Maria De Lourdes Costarrica, Peter Karim, and Ben Embarek. “Powdered Infant Formula as a Source of Salmonella Infection in Infants.” Powdered Infant Formula as a Source of Salmonella Infection in Infants 46.2 (2008): 268-73. Chicago Journals. 1 Jan. 2009. Web. 30 Mar. 2010. <>.

Maki, Dennis G. “Coming to Grips with Foodborne Infection - Peanut Butter, Peppers, and Nationwide Salmonella Outbreaks.” Coming to Grips with Foodborne Infection - Peanut Butter, Peppers, and Nationwide Salmonella Outbreaks 360.10 (2009): 949-53. The New England Journal of Medicine. 11 Feb. 2009. Web. 30 Mar. 2010. <>.

Lite, Jordan. “More Salmonella: U.S. Searching for Origin of Latest, Widespread Outbreak.” Scientific American (2009). Scientific American. 8 Jan. 2009. Web. 30 Mar. 2010. <>.

Wikipedia contributors. “Salmonella.” Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 30 Mar. 2010. Web. 30 Mar. 2010.

“Foodborne Illness and Disease.” United States Department of Agriculture. 20 Sept. 2006. Web. 30 Mar. 2010. <>.

“serotype.” The American Heritage├é┬« Dictionary of the English Language, Fourth Edition. Houghton Mifflin Company, 2004. 31 Mar. 2010. <>.