1. Organism

Salmonella is a motile, non-sporeforming, Gram- negative, rod-shaped bacterium in the family Enterobacteriaceae and the tribe Salmonellae. Non-motile variants include S. Gallinarum and S. Pullorum. The genus Salmonella is divided into two species that can cause illness in humans:

• S. enterica

• S. bongori
Salmonella enterica, which is of the greatest public 
health concern, is comprised of six subspecies:

     o S. enterica subsp. enterica (I)

     o S. enterica subsp. salamae (II)

     o S. enterica subsp. arizonae (IIIa)

     o S. enterica subsp. diarizonae (IIIb)

     o S. enterica subsp. houtenae (IV)

     o S. enterica subsp. indica (VI)

Salmonella is further subdivided into serotypes,
based on the Kaufmann-White typing scheme first
published in 1934, which differentiates Salmonella
strains by their surface and flagellar antigenic
properties. Salmonella spp. are commonly referred
to by their serotype names. For example,
Salmonella enterica subsp. enterica is further
divided into numerous serotypes, including S.
Enteritidis and S. Typhimurium, which are
common in the U.S. (Note that species names are
italicized, but serotype names are not.)

When
Kaufmann first proposed the scheme, 44 serotypes had been discovered. As of 2007, the number of serotypes discovered was 2,579.

2. Disease

Salmonella can cause two types of illness, depending on the serotype:
(1) nontyphoidal salmonellosis and (2) typhoid fever, both of which are described below. The 
symptoms of nontyphoidal salmonellosis can be quite unpleasant, but this illness is generally self-limiting among healthy people with intact immune systems (although it can cause life- threatening illness even in healthy people). Typhoid fever is more serious and has a higher mortality rate than does nontyphoidal salmonellosis.

Nontyphoidal Salmonellosis

• Caused by serotypes other than S. Typhi and S. Paratyphi A.

• Mortality: Generally less than 1%; however, S. Enteritidis has a 3.6% mortality rate in outbreaks in nursing homes and hospitals, with the elderly being particularly affected.

• Onset: 6 to 72 hours after exposure.

• Infective dose: As low as one cell, depending on age and health of host and strain 
differences among members of the genus.

• Symptoms: Nausea, vomiting, abdominal cramps, diarrhea, fever, headache.

• Duration: Symptoms generally last 4 to 7 days, with acute symptoms usually lasting 1 to 2 days or longer, depending on host factors, the dose ingested, and strain characteristics.

• Complications: (1) Dehydration and electrolyte imbalance may occur as a result of diarrhea and vomiting. This can lead to death in the very young, the elderly, and the immunocompromised, if not treated promptly. (2) In 2% of culture-proven cases, reactive arthritis (i.e., arthritis from an immune reaction to the infection – an autoimmune response – rather than directly from the infection itself) may follow 3 to 4 weeks after the onset of acute symptoms. Indications of reactive arthritis may include, for example, joint inflammation, urethritis, uveitis, and/or conjunctivitis. (3) Nontyphoidal Salmonella can sometimes escape from the gastrointestinal tract into the body and cause blood poisoning (septicemia) or infect the blood, internal organs, and/or joints (bacteremia). S. Dublin is sometimes associated with this complication.

• Route of entry: oral (e.g., ingestion of contaminated food, fecal particles, or contaminated water).

• Pathway: Penetration and passage of Salmonella organisms from gut lumen into epithelium of small intestine, where inflammation occurs. There is evidence that enterotoxin may be produced, perhaps within enterocytes.

Typhoid Fever

• Caused by serotypes S. Typhi and S. Paratyphi A, both of which are found only in humans.

• Mortality: Untreated, as high as 10%.

• Onset: Generally 1 to 3 weeks, but may be as long as 2 months after exposure.

• Infective dose: Fewer than 1,000 cells.

• Symptoms: High fever, from 103° to 104°F; lethargy; gastrointestinal symptoms, including abdominal pains and diarrhea or constipation; headache; achiness; loss of appetite. A rash of flat, rose-colored spots sometimes occurs.

• Duration: Generally 2 to 4 weeks.

• Illness / Complications: Septicemia, with colonization of other tissues and organs; e.g., may lead to endocarditis. Septic arthritis may occur, in which the infection directly affects the joints and may be difficult to treat. Chronic infection of the gallbladder may occur, which may cause the infected person to become a carrier.

• Route of entry: Oral (e.g., ingestion of contaminated food, fecal particles, or contaminated water).

• Pathway: Penetration and passage of typhoid Salmonella organisms from gut lumen into epithelium of small intestine and into the bloodstream (i.e., septicemia), which may carry the organisms to other sites in the body, where inflammation occurs. There is evidence that enterotoxin may be produced, perhaps within enterocytes. 
3. Frequency of Disease 
Annually in the United States:

Nontyphoidal salmonellosis – A recent report from the Centers for Disease Control and Prevention (CDC) estimates that 1,027,561 cases of domestically acquired nontyphoidal salmonellosis occur annually in the U.S., when under-reporting and under-diagnosis are taken into account.

Typhoid fever – In terms of domestically acquired S. enterica serotype Typhi, the CDC recently estimated that a mean of 1,821 cases occur annually in the U.S. Additional cases in the U.S. are associated with foreign travel. The report estimates that 433 cases of typhoid fever in the U.S., overall (i.e., whether or not they are domestically acquired), are culture-confirmed. The last case of a foodborne, noncarrier-based typhoid outbreak in the U.S. was in 1999 and was associated with the tropical fruit mamey. 
4. Sources 
Salmonella is widely dispersed in nature. It can colonize the intestinal tracts of vertebrates, including livestock, wildlife, domestic pets, and humans, and may also live in environments such as pond-water sediment. It is spread through the fecal-oral route and through contact with contaminated water. (Certain protozoa may act as a reservoir for the organism). It may, for example, contaminate meat, farm-irrigation water (thus contaminating produce in the field), soil and insects, factory equipment, hands, and kitchen surfaces and utensils. 
Since S. Typhi and S. Paratyphi A are found only in human hosts, the usual sources of these organisms in the environment are drinking and/or irrigation water contaminated by untreated sewage. It is highly recommended that only potable water and cooked vegetables be consumed in areas where these organisms are endemic. 
Various Salmonella species have long been isolated from the outside of egg shells, but S. Enteritidis can be present inside the egg. This and other information strongly suggest vertical transmission; i.e., deposition of the organism on the albumen (egg white) side of the yolk-sack membrane (vitelline membrane) by an infected hen, prior to shell formation.

Outbreaks also have been linked to the handling of certain animals sometimes kept as pets, such as turtles, frogs, and chicks.

Food Sources

Although Salmonella traditionally was thought of as being associated with animal products in the past, fresh produce also has been the source of major outbreaks, particularly recently. The organism also survives well on low-moisture foods, such as spices, which have been the vehicles for large outbreaks.

A few examples of foods that have been linked to Salmonella illness include meats, poultry, eggs, milk and dairy products, fish, shrimp, spices, yeast, coconut, sauces, unpasteurized salad dressings, cake mixes, cream-filled desserts and toppings that contain raw egg, dried gelatin, peanut butter, cocoa, produce (fruits and vegetables, such as tomatoes, peppers, and cantaloupes), and chocolate.

Cross Contamination

Cross contamination occurs when Salmonella is spread from a contaminated source – a contaminated food, infected food handler or animal – to other foods or objects in the environment. An example of how this may occur is when potentially contaminated raw meats, poultry, seafood, produce, or eggs are not kept separate from each other during preparation or cooking, or when a food handler does not adequately clean utensils, surfaces, equipment, and hands after they have come into contact with these products.

The contamination can spread to factory and equipment surfaces, as well as kitchen surfaces and utensils. Cross contamination may occur at any point in the food process.

Cross contamination also may occur from handling pets or wildlife, such as turtles or frogs (or their water, soil, or food and water bowls), then handling food, food-preparation utensils, or other objects in the environment. (Even culinary frog legs have caused outbreaks of salmonellosis.)

5. Diagnosis

Serological identification of cultural isolates from stool. Genetic identification of approximately 100 Salmonella serotypes from pure culture is now possible, but the remaining 2,400-plus serotypes can be identified only through traditional serotyping.

6. Target Populations

Anyone, of any age, may become infected with Salmonella. Particularly vulnerable are people with weak immune systems, such as the very young and the elderly, people with HIV or chronic illnesses, and people on some medications; for example, chemotherapy for cancer or the immunosuppressive drugs used to treat some types of arthritis. People with HIV are estimated to have salmonellosis at least 20 times more than does the general population and tend to have recurrent episodes.

7. Foods Analysis

Isolation and detection methods have been developed for many foods having prior history of Salmonella contamination. Conventional culture and identification methods may require 4 to 6 days for presumptive results. To screen foods, several rapid methods are available, which require 1 to 2 days. These rapid methods include antibody and molecular (DNA or RNA) based assays, but in most cases, require a cultural means to confirm the presence of Salmonella, for regulatory purposes.

8. Examples of Outbreaks

For information on recent outbreaks, see the Morbidity and Mortality Weekly Reports from the Centers for Disease Control and Prevention (CDC).

9. Other Resources

• The CDC provides information about Salmonella, including information about preventing Salmonella Enteritidis infection, on avoiding salmonellosis from animal-handling, and typhoid fever.

• Loci index for genome Salmonella Enteritidis is available from GenBank.

The CDC estimates that 50 million Americans each year get sick from foodborne illnesses, including about 3,000 who die.

The report released Tuesday is based on foodborne infections in only 10 states, or about 15 percent of the American population. But it has information that other databases lack and is believed to be a good indicator of food poisoning trends.

More than 19,000 cases of food poisoning were reported in those states last year. That was up from 17,500 cases in 2009, and about 18,500 in 2008.

Last year, there were 4,200 hospitalizations and 68 deaths in those states.

One of the largest U.S. outbreaks last year involved salmonella tainted eggs that may have sickened as many as 56,000, according to a CDC estimate. That probably contributed to the increase seen in Tuesday's report, said Dr. Christopher Braden, a CDC epidemiologist.

Salmonella infection occurs when the bacteria are ingested, typically from food derived from infected food-animals, but it can also occur by ingesting the feces of an infected animal or person. Food sources include raw or undercooked eggs/egg products, raw milk or raw milk products, contaminated water, meat and meat products, and poultry. Raw fruits and vegetables contaminated during slicing have been implicated in several foodborne outbreaks.

Symptoms of Salmonella infection

Reiter’s Syndrome, which includes and is sometimes referred to, as reactive arthritis is an uncommon, but debilitating, result of a Salmonella infection. The symptoms of Reiter’s Syndrome usually occur between one and three weeks after the infection. Reiter’s Syndrome is a disorder that causes at least two of three seemingly unrelated symptoms: reactive arthritis, conjunctivitis (eye irritation), and urinary tract infection. The arthritis associated with Reiter’s Syndrome typically affects the knees, ankles, and feet, causing pain and swelling. Wrists, fingers and other joints can be affected, though with less frequency. With Reiter’s Syndrome, the affected person commonly develops inflammation where the tendon attaches to the bone, a condition called enthesopathy. Some people also develop heel spurs, bony growths in the heel that cause chronic or long-lasting foot pain. Arthritis from Reiter’s Syndrome can also affect the joints of the back and cause spondylitis, inflammation of the vertebrae in the spinal column. The duration of reactive arthritis symptoms can vary greatly. Most of the literature suggests that the majority of affected persons recover within a year. The condition, can, however, be permanent.

Detection and treatment of Salmonella Infection

Salmonella bacteria are discovered in stool cultures. Although blood cultures are rarely positive, bacteremia (bacteria in the blood stream) does occur in 5% of adults with Salmonella gastroenteritis and can result in spread to the heart (endocarditis), spleen, bone (osteomyelitis), and joints (Reiter’s Syndrome or reactive arthritis). However, blood cultures are often not performed and in most cases the blood stream is not infected. In the stool, the laboratory is challenged to pick out Salmonella from many other similar bacteria that are normally present. In addition, many persons submit cultures after they have started antibiotics, which may make it even more difficult for a microbiology lab to grow Salmonella. So, the diagnosis of salmonellosis may be problematic and many mild cases are culture negative.

Salmonella infections usually resolve in five to seven days, and many times require no treatment, unless the affected person becomes severely dehydrated or the infection spreads from the intestines. Persons with severe diarrhea may require rehydration, often with intravenous fluids. Treatment with antibiotics is not usually necessary, unless the infection spreads from the intestines, or otherwise persists, in which case the infection can be treated with ampicillin, gentamicin, trimethoprim/sulfamethoxazole, or ciprofloxacin. Some Salmonella bacteria have become resistant to antibiotics, possibly as a result of the use of antibiotics to promote the growth of feed animals.

For those persons who develop Reiter’s Syndrome, symptomatic treatment with high doses of a nonsteroidal anti-inflammatory drug and steroid injections into affected joints can be helpful in reactive arthritis. For people with severe joint inflammation, injections of corticosteroids directly into the affected joint may reduce inflammation. A small percentage of patients with reactive arthritis have severe symptoms that cannot be controlled with these treatments, in which case medicine that suppresses the immune system, such as sulfasalazine or methotrexate, may be effective. Exercise, when introduced gradually, may help improve joint function. Topical corticosteroids can be applied directly on the skin lesions associated with reactive arthritis.

Preventing Salmonella Infection

To prevent salmonellosis, cook poultry, ground beef, and eggs thoroughly before eating. In order to insure that eggs do not contain viable Salmonella they must be cooked at least until the yoke is solid, and meat and poultry must reach 160∫F or greater throughout. Be particularly careful with foods prepared for infants, the elderly, and those with a compromised immune system.

Do not eat or drink foods containing raw eggs, such as homemade eggnog and hollandaise sauce. Avoid drinking raw (unpasteurized) milk or products made from raw milk.

Wash hands, kitchen work surfaces, and utensils with soap and water immediately after they have been in contact with foods of animal origin. Also, wash hands with soap after handling reptiles, amphibians or birds, or after contact with pet feces. Infants and immunocompromised persons should have no direct or indirect contact with such pets.

Salmonella Infection Complications

The following infections result in very few people, but the few who are diagnosed will suffer for the rest of their lives.

Irritable Bowel Syndrome (IBS)

A recently published study surveyed the extant scientific literature and noted that post-infectious irritable bowel syndrome (PI-IBS) is a common clinical phenomenon first described over five decades ago. The Walkerton Health Study further notes that:

Between 5% and 30% of patients who suffer an acute episode of infectious gastroenteritis develop chronic gastrointestinal symptoms despite clearance of the inciting pathogens.

In terms of its own data, the “study confirm[ed] a strong and significant relationship between acute enteric infection and subsequent IBS symptoms.” The WHS also identified risk factors for subsequent IBS, including: younger age; female sex; and four features of the acute enteric illness—diarrhea for > 7days, presence of blood in stools, abdominal cramps, and weight loss of at least ten pounds.

Irritable bowel syndrome (IBS) is a chronic disorder characterized by alternating bouts of constipation and diarrhea, both of which are generally accompanied by abdominal cramping and pain. In one recent study, over one-third of IBS sufferers had had IBS for more than ten years, with their symptoms remaining fairly constant over time. IBS sufferers typically experienced symptoms for an average of 8.1 days per month.

As would be expected from a chronic disorder, IBS sufferers required more time off work, spent more days in bed, and more often cut down on usual activities, when compared with non-IBS sufferers. And even when able to work, a significant majority (67%), felt less productive at work because of their symptoms. IBS symptoms also have a significantly deleterious impact on social well-being and daily social activities, such as undertaking a long drive, going to a restaurant, or taking a vacation. Finally, while a patient’s psychological state may influence the way in which he or she copes with illness, and responds to treatment, there is no evidence that supports the theory that psychological disturbances in facts cause IBS or its symptoms.

Reiter’s Syndrome

Several bacteria, including Salmonella, induce septic arthritis. The resulting joint pain and inflammation can resolve completely over time or permanent joint damage can occur. In a small number of persons, the joint inflammation is accompanied by conjunctivitis and uveitis, (inflammation of the eyes), and cystitis (painful urination). This triad of symptoms is called Reiter's Syndrome. Reiter’s Syndrome is a special form of reactive arthritis, autoimmune disorder triggered by the Salmonella infection. It occurs in persons with a genetic predisposition and can last for a year or more. Antibiotic treatment does not make a difference in whether or not the person later develops arthritis.

The term reactive arthritis refers to an inflammation of one or more joints, following an infection localized at another site distant from the affected joints. The predominant site of the infection is the gastrointestinal tract. During outbreaks of Salmonella infections, reactive arthritis incidences from 1% to 15% have been reported.

References

Angulo FJ, Baker NL, Olsen SJ, Anderson A, Barrett TJ. (2004). Antimicrobal Use in Agriculture: Controlling the Transfer of Antimicrobal Resistance to Humans. Seminars in Pediatric Infectious Diseases. 15(2): 78-85.

Angulo FJ, Nargund VN, and Chiller TC. (2004). Evidence of an Association Between Use of Anti-microbial Agents in Food Animals and Anti-microbial Resistance Among Bacteria Isolated from Humans and the Human Health Consequences of Such Resistance J. Vet. Med. B Infect. Dis. Vet. Public Health. 51(8-9):374-9.

CDC. (2005, October 13). Salmonella: Technical Fact Sheet. Retrieved August 29, 2007 from Centers for Disease Control and prevention Web site, http://www.cdc.gov/ncidod/dbmd/diseaseinfo/salmonellosis_t.htm.

CDC. 2007. Salmonella Surveillance: Annual Summary, 2005. Atlanta, Georgia: US Department of Health and Human Services.

Glynn MK, Bopp C, Dewitt W, Dabney P, Mokhtar M, Angulo FJ. (1998). Emergence of multidrug-resistant Salmonella enterica serotype typhimurium DT104 infections in the United States. N Engl J Med 338:1333–1338.

Hill Gaston JS, Lillicrap MS. (2003). Arthritis associated with enteric infection. Best Practices & Research Clinical Rheumatology 17(2):219-239.

Inman RD, Johnston MEA, Hodge M, Falk J, and Helewa A. (1988). Postdysenteric Reactive Arthritis, A Clinical and Immunogenic Study following an Outbreak of Salmonellosis. Arthritis and Rheumatism 31:1377-1383.

Mayo Clinic. (2007, April 12). Salmonella. Retrieved August 29, 2007 from Mayo Clinic Web site, http://www.mayoclinic.com/health/salmonella/DS00926.

Mead PM, Slutsker L, Dietz V, McCaig LF, Bresee JS, Shapiro C, Griffin PM, and Tauxe RV. (1999). Food-related Illness and Death in the United States. Emerg. Infect. Dis. 5:607-625.

MMWR Recomm Rep. (2001). Diagnosis and management of foodborne illnesses: a primer for physicians. January 26, 2001 / 50 (RR-2):1-69. Atlanta, GA: Centers for Disease Control and Prevention.

MMWR Surveillance Summaries, Appendix B. (1996). Guidelines for confirmation of foodborne-disease outbreaks. October 25, 1996 / 45:(SS-5) 59-66. Atlanta, GA: Centers for Disease Control and Prevention.

MMWR Weekly. (1996). Guidelines for confirmation of foodborne-disease outbreaks. October 25, 1996 / 45(S-5): 58-66. Atlanta, GA: Centers for Disease Control and Prevention.

MMWR Weekly. (2001). Summary of Notifiable Diseases, United States, 1999. April 06, 2001 / 48(53):1-104. Atlanta, GA: Centers for Disease Control and Prevention.

MMWR Weekly. (2006). Preliminary FoodNet Data on the Incidence of Infection with Pathogens Transmitted Commonly Through Food – 10 States, United States, 2005. April 14, 2006 / 55(14);392-395. Atlanta, GA: Centers for Disease Control and Prevention.

Stevenson JE, White DG, Torpey III DJ, Craig AS, Smith KE, Park MM, Pascucilla MA, Anderson AD, and the NARMS Working Group. (2002). Enhanced Surveillance for Antimicrobial Resistance Among Enteric Bacteria: NARMS Retail Food Study. International Conference on Emerging Infectious Diseases. Atlanta, GA, March 2002.

Wallinga, D. (2002, October). Antimicrobial Use in Animal Feed: an Ecological and Public Health Problem. Minnesota Medicine. 85. Retrieved January 16, 2008, from http://www.mmaonline.net/publications/MNMed2002/October/Wallinga.html.

Click on above.

The reported incidence of Salmonella illnesses is about 14 cases per each 100,000 persons (MMWR Weekly, 2006), amounting to approximately 30,000 confirmed cases of salmonellosis yearly in the U.S. (CDC, 2005, October 13). In 2005, just over 36,000 cases were reported from public health laboratories across the nation, representing a 12 percent decrease compared with the previous decade, but a 1.5 percent increase over 2004 (CDC, 2007).

As only about 3 percent of Salmonella cases are officially reported nationwide, and many milder cases are never diagnosed, the true incidence is undoubtedly much higher (Mead, 1999). The CDC estimates that 1.4 million cases occur annually (CDC, 2005, October 13). Approximately 600 deaths are caused by Salmonella infections in the U.S. every year, accounting for 31 percent of all food-related deaths (CDC, 2005, October 13; MMWR Weekly, 2001).

Theobald Smith, research-assistant to Daniel E. Salmon, discovered the first strain of Salmonella - Salmonella cholerae suis - in 1885. Since that time, the number of strains (technically termed serotypes or serovars) of Salmonella known to cause salmonellosis has increased to over 2,300. Salmonella typhi, the strain that causes typhoid fever, is uncommon in the U.S., while Salmonella enterica serotype Typhimurium and Salmonella enterica serotype Enteritidis have been the most frequently reported illnesses since 1993. Salmonella enterica serotypes Newport, Mississippi and Javiana have been increasingly identified as the source of illness (MMWR Weekly, 2006).

Symptoms of Salmonella Infection

An infectious dose of Salmonella is small, probably from 15 to 20 cells. Typically, non-typhoidal Salmonella produces a self-limiting febrile gastrointestinal illness that is indistinguishable from that caused by other bacterial enteric pathogens. Dehydration is the principal clinical concern. The incubation period - the time between ingestion of Salmonella bacteria and the onset of illness - varies from six to 72 hours (Mayo Clinic, 2007, April 12; MMWR Recomm Rep, 2001).

Salmonella can cause three different kinds of illness: gastroenteritis, typhoid fever, and bacteremia.

Symptoms of Salmonella gastroenteritis include diarrhea, abdominal cramps, fever, nausea, and/or vomiting. In mild cases diarrhea may be non-bloody, occur several times per day, and not be very voluminous; in severe cases it may be frequent, bloody and/or mucoid, and of high volume.

Fever generally occurs in the 100°F to 102°F (38°C to 39°C) range. Vomiting is less common than diarrhea. Headaches, myalgias (muscle pain), and arthralgias (joint pain) are often reported as well. Whereas the diarrhea typically lasts 24 to 72 hours, patients often report fatigue and other nonspecific symptoms lasting 7 days or longer.

Complications of Salmonella Infection

Typhoid fever, also known as enteric fever, is caused by Salmonella serotype typhi. The onset of symptoms usually occurs between 5 and 21 days after ingestion of Salmonela typhi bacteria. Symptoms may include constipation, cough, sore throat, headache, and a rash on the infected individual's chest, as well as the slowing of the heartbeat and enlargement of the liver and spleen (Mayo Clinic, 2007, April 12).

Bacteremia is characterized by infection of tissues surrounding the brain and spinal cord (meningitis) and infection within the bloodstream (sepsis). This condition occurs when Salmonella enter and circulate within an infected individual's bloodstream, and is accompanied by few symptoms (Mayo Clinic, 2007, April 12).

The three most common symptoms of Reiter’s syndrome are arthritis, eye irritation, and urinary tract symptoms. The arthritis associated with Reiter’s syndrome typically affects the knees, ankles, and feet, causing pain and swelling. Wrists, fingers and other joints can be affected, though with less frequency. Patients with Reiter’s syndrome commonly develop inflammation where the tendon attaches to the bone, a condition called enthesopathy. Some patients with Reiter’s syndrome also develop heel spurs, bony growths in the heel that cause chronic or long-lasting foot pain. Arthritis from Reiter’s syndrome can also affect the joints of the back and cause spondylitis, inflammation of the vertebrae in the spinal column. The duration of reactive arthritis symptoms can vary greatly. Most of the literature suggests that the majority of patients recover within a year. The condition, can, however, be permanent. One study found nearly 50 percent of patients with post dysenteric reactive arthritis continued to have symptoms roughly one year after onset (Inman, et al., 1998).

The involvement of the eye in Reiter’s syndrome is most commonly manifested as conjunctivitis, inflammation of the mucous membrane that covers the eyeball, or uveitis, an inflammation of the inner eye. Conjunctivitis and uveitis can cause redness of the eyes, eye pain and irritation, and blurred vision.

The third site for Reiter’s syndrome symptoms is the urogenital tract. This includes the prostate, urethra, and penis in men and the fallopian tubes, uterus, and vagina in women. Men may notice an increased need to urinate, a burning sensation when urinating, and a discharge from the penis. Some men also develop prostatitis. Symptoms of prostatitis include fever, chills, increased need to urinate, and a burning sensation when urinating.

How is Salmonella Infection Diagnosed?

Salmonella bacteria can be detected in stool or blood cultures, and a diagnosis of salmonellosis is confirmed by culture.  Specimens of blood or feces are placed in nutrient broth or on agar and incubated for 2-3 days.  After that time, a trained microbiologist can recognize Salmonella bacteria, if present, by its unique characteristics.

In the stool, the laboratory is challenged to pick out Salmonella from many other similar bacteria that are normally present.  Many persons submit specimens for testing after they have started antibiotics, which may make it even more difficult for a lab to grow Salmonella.  So, the diagnosis of salmonellosis may be problematic and many mild cases are culture-negative.

Blood cultures are often not performed and in most cases the blood stream is not infected.  Bacteremia does occur in 5 percent of adults with Salmonella gastroenteritis and can result in hematogenous spread to the heart (endocarditis), spleen, bone (osteomyelitis), and joints (reactive arthritis), although blood cultures are rarely positive.

Treatment for Salmonella Infection

Salmonella infections usually resolve in five to seven days, and many times require no treatment unless the patient becomes severely dehydrated or the infection spreads from the intestines. Persons with severe diarrhea may require re-hydration, often with intravenous fluids.

Treatment with antibiotics is not usually necessary; however, if the infection spreads from the intestines, or otherwise persists, the infection can be treated with ampicillin, gentamicin, trimethoprim/sulfamethoxazole, ceftriaxone, amoxicillin, or ciprofloxacin.  The length of treatment varies depending on the extent of a patient’s illness, and can range from 14 days for enteric fever to six weeks for bactremia (Mayo Clinic, 2007, April 12).  Some Salmonella bacteria have become antibiotic-resistant.

Consult your healthcare provider if you believe you have become ill with salmonellosis.

Antimicrobial Resistance in Salmonella Bacteria

Antimicrobial resistance in bacteria is an emerging and increasing threat to human health. Physicians should be aware that antimicrobial resistance is increasing in foodborne pathogens and that patients who are prescribed antibiotics are at increased risk for acquiring antimicrobial-resistant foodborne infections. In addition, “…increased frequency of treatment failures for acute illness and increased severity of infection may be manifested by prolonged duration of illness, increased frequency of bloodstream infections, increased hospitalization or increased mortality,” (Angulo, Nargund, & Chiller, 2004).

The use of antimicrobial agents in the feed of food animals is estimated by the FDA to be over 100 million pounds per year. Estimates range from 36 to 70 percent of all antibiotics produced in the United States are used in a food animal feed or in prophylactic treatment to prevent animal disease.  In 2002, the Minnesota Medical Association published an article by David Wallinga, M.D., M.P.H. who wrote:

According to the [Union of Concerned Scientists], 70 percent of all the antimicrobials used in the United States for all purposes—or about 24.6 million pounds annually—are fed to poultry, swine, and beef cattle for nontherapeutic purposes, in the absence of disease. Over half are “medically important” antimicrobials, identical or so closely related to human medicines that resistance to the animal drug can confer resistance to the similar human drug. Penicillins, tetracyclines, macrolides, streptogramins, and sulfonamides are prominent examples. (Wallinga, 2002).

The National Antimicrobial Resistance Monitoring System (NARMS) reported that Campylobacter has been recovered from 47 percent of chicken breasts tested in recent studies. In the same NARMS studies, five multi-drug resistant strains of Salmonella Newport were recovered from ground beef, ground turkey, and pork chops.

According to the report, “…antimicrobial resistance among these foodborne bacteria is not uncommon and often associated with the use of antimicrobial agents in food animals,” (Stevenson, et al., 2002).  Ceftriaxone-resistant Salmonella has also been reported (Fey et al., 2000). The emergence of multidrug-resistant Salmonella typhimurium in the United States is another example of a drug-resistant bacteria spreading from animals to humans (Glynn et al., 1998).

A large proportion of serotype Typhimurium isolates were resistant to multiple antimicrobial drugs; in a 2003 national survey, 45% were resistant to one or more drugs and 26% had a five-drug resistance pattern characteristic of a single phage type, DT104 (2). Similarly, serotype Newport has emerged as a major multidrug-resistant pathogen (CDC, 2007).

The use of antibiotics in feed for food animals, on animals prophylactically to prevent disease, and the use of antibiotics in humans unnecessarily must be reduced. European countries have reduced the use of antibiotics in animal feed and have seen a corresponding reduction in antibiotic-resistant illnesses in humans (Angulo, Baker, et al., 2004).

How to Prevent a Salmonella Infection

Persons most at-risk for contracting Salmonellosis include:

• Individuals sharing households with infected persons
• Owners of pet reptiles, such as an iguanas, lizards or turtles
• Individuals with compromised immune systems, such as people with AIDS, cancer patients, and transplant recipients
• Individuals with inflammatory bowel disease
• Individuals with sickle cell disease
• Individuals who have illnesses such as malaria or sickle cell anemia
• Individuals using corticosteroids
• Individuals who use antacids (Mayo Clinic, 2007, April 12)

To prevent Salmonella bacterial infection:

• Cook poultry, ground beef, and eggs thoroughly before eating. In order to insure that eggs do not contain viable Salmonella they must be cooked at least until the yoke is solid and meat and poultry must reach 160ºF or greater throughout. Pasteurized eggs are also available in some areas and for foodservice organizations (MMWR Weekly, 1996).
• Do not eat or drink foods containing raw eggs. Examples include homemade eggnog, hollandaise sauce, and undercooked French toast.
• Never drink raw (unpasteurized) milk.
• If you are served undercooked meat, poultry, or eggs in a restaurant don't hesitate to send your food 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 foods of animal origin.
• Be particularly careful with foods prepared for infants, the elderly, and those with a compromised immune system.
• Wash hands with soap after handling reptiles, amphibians or birds, or after contact with pet feces. Infants and persons with compromised immune systems should have no direct or indirect contact with such pets.

Outbreaks

* 2008 Cantaloupe Salmonella Outbreak

* 2008 Malt-O-Meal Salmonella Agona

* Alamosa, Colorado Municipal Water System Salmonella Outbreak

* Banquet (ConAgra) Pot Pie Salmonella Outbreak

* Black Forest Bakery Salmonella Outbreak

* Brook-Lea Salmonella Outbreak

* Cafe Santa Fe Salmonella Outbreak

* Chili’s Salmonella Outbreak

* Corky & Lenny’s Deli Salmonella Outbreak

* Golden Corral Salmonella Outbreak

* Harmony Farms Salmonella Outbreak

* KFC Salmonella Outbreak

* Kunick Cantaloupe Salmonella Outbreak

* Linh’s Bakery Salmonella Outbreak

* Malt-O-Meal Salmonella Outbreak

* Old South Restaurant Salmonella Outbreak

* Orchid Island Orange Juice Salmonella Outbreak

* Paramount Farms Salmonella Outbreak

* Peter Pan and Great Value Peanut Butter Salmonella Outbreak

* Quality Inn and Bogey’s Restaurant Salmonella Outbreak

* San Antonio Taco Salmonella Outbreak

* Seasons on the Pond Salmonella Outbreak

* Sheetz and Coronet Foods Salmonella Outbreak

* Shipley Sales Cantaloupe Salmonella Outbreak

* Sun Orchard Orange Juice Salmonella Outbreak

* Sunset House Salmonella Outbreak

* Sushi King Salmonella Outbreak

* Taste of Chicago Salmonella Outbreak

* Veggie Booty Salmonella Outbreak

* Wal-Mart Salmonella Outbreak

* Western Sizzlin’ Salmonella Outbreak

References

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* Angulo FJ, Nargund VN, and Chiller TC. (2004). Evidence of an Association Between Use of Anti-microbial Agents in Food Animals and Anti-microbial Resistance Among Bacteria Isolated from Humans and the Human Health Consequences of Such Resistance J. Vet. Med. B Infect. Dis. Vet. Public Health. 51(8-9):374-9.

* CDC. (2005, October 13). Salmonella: Technical Fact Sheet. Retrieved August 29, 2007 from Centers for Disease Control and prevention Web site, http://www.cdc.gov/ncidod/dbmd/diseaseinfo/salmonellosis_t.htm.

* CDC. 2007. Salmonella Surveillance: Annual Summary, 2005. Atlanta, Georgia: US Department of Health and Human Services.

* Glynn MK, Bopp C, Dewitt W, Dabney P, Mokhtar M, Angulo FJ. (1998). Emergence of multidrug-resistant Salmonella enterica serotype typhimurium DT104 infections in the United States. N Engl J Med 338:1333–1338.

* Hill Gaston JS, Lillicrap MS. (2003). Arthritis associated with enteric infection. Best Practices & Research Clinical Rheumatology 17(2):219-239.

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* Mayo Clinic. (2007, April 12). Salmonella. Retrieved August 29, 2007 from Mayo Clinic Web site, http://www.mayoclinic.com/health/salmonella/DS00926.

* Mead PM, Slutsker L, Dietz V, McCaig LF, Bresee JS, Shapiro C, Griffin PM, and Tauxe RV. (1999). Food-related Illness and Death in the United States. Emerg. Infect. Dis. 5:607-625.

* MMWR Recomm Rep. (2001). Diagnosis and management of foodborne illnesses: a primer for physicians. January 26, 2001 / 50 (RR-2):1-69. Atlanta, GA: Centers for Disease Control and Prevention.

* MMWR Surveillance Summaries, Appendix B. (1996). Guidelines for confirmation of foodborne-disease outbreaks. October 25, 1996 / 45:(SS-5) 59-66. Atlanta, GA: Centers for Disease Control and Prevention.

* MMWR Weekly. (1996). Guidelines for confirmation of foodborne-disease outbreaks. October 25, 1996 / 45(S-5): 58-66. Atlanta, GA: Centers for Disease Control and Prevention.

* MMWR Weekly. (2001). Summary of Notifiable Diseases, United States, 1999. April 06, 2001 / 48(53):1-104. Atlanta, GA: Centers for Disease Control and Prevention.

* MMWR Weekly. (2006). Preliminary FoodNet Data on the Incidence of Infection with Pathogens Transmitted Commonly Through Food – 10 States, United States, 2005. April 14, 2006 / 55(14);392-395. Atlanta, GA: Centers for Disease Control and Prevention.

* Stevenson JE, White DG, Torpey III DJ, Craig AS, Smith KE, Park MM, Pascucilla MA, Anderson AD, and the NARMS Working Group. (2002). Enhanced Surveillance for Antimicrobial Resistance Among Enteric Bacteria: NARMS Retail Food Study. International Conference on Emerging Infectious Diseases. Atlanta, GA, March 2002.

* Wallinga, D. (2002, October). Antimicrobial Use in Animal Feed: an Ecological and Public Health Problem. Minnesota Medicine. 85. Retrieved January 16, 2008, from http://www.mmaonline.net/publications/MNMed2002/October/Wallinga.html.