|Electron micrograph showing Salmonella typhimurium (red) invading cultured human cells|
|Symptoms||Diarrhea, fever, abdominal cramps, vomiting|
|Complications||Reactive arthritis, irritable bowel syndrome|
|Usual onset||0.5–3 days post exposure|
|Risk factors||Old, young, weak immune system, bottle feeding, proton pump inhibitors|
|Diagnostic method||Stool test, blood tests|
|Differential diagnosis||Other types of gastroenteritis|
|Prevention||Proper preparation and cooking of food|
|Treatment||Fluids by mouth, intravenous fluids, antibiotics|
|Frequency||1.2 million non–typhoidal cases per year (US)|
Salmonellosis is a symptomatic infection caused by bacteria of the Salmonella type.The most common symptoms are diarrhea, fever, abdominal cramps, and vomiting. Symptoms typically occur between 12 hours and 36 hours after exposure, and last from two to seven days. Occasionally more significant disease can result in dehydration. The old, young, and others with a weakened immune system are more likely to develop severe disease. Specific types of Salmonella can result in typhoid fever or paratyphoid fever.
Bacteria are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep portions of Earth's crust. Bacteria also live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, and only about half of the bacterial phyla have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology.
Salmonella is a genus of rod-shaped (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two species of Salmonella are Salmonella enterica and Salmonella bongori. S. enterica is the type species and is further divided into six subspecies that include over 2,600 serotypes.
Diarrhea is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin with loss of the normal stretchiness of the skin and irritable behaviour. This can progress to decreased urination, loss of skin color, a fast heart rate, and a decrease in responsiveness as it becomes more severe. Loose but non-watery stools in babies who are exclusively breastfed, however, are normal.
There are two species of Salmonella: Salmonella bongori and Salmonella enterica with many subspecies.Infection is usually spread by eating contaminated meat, eggs, or milk. Other foods may spread the disease if they have come into contact with manure. A number of pets including cats, dogs, and reptiles can also carry and spread the infection. Diagnosis is by a stool test or blood tests.
In biology, a species ( ) is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more closely they represent problematic species concepts. For example, the boundaries between closely related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, and in a ring species. Also, among organisms that reproduce only asexually, the concept of a reproductive species breaks down, and each clone is potentially a microspecies.
Salmonella bongori is a pathogenic bacterium belonging to the genus Salmonella, and was earlier known as Salmonella subspecies V or S. enterica subsp. bongori or S. choleraesuis subsp. bongori. It is a Gram-negative, rod-shaped bacterium (bacillus), which causes a gastrointestinal disease called salmonellosis, characterized by cramping and diarrhoea. It is typically considered a microbe of cold-blooded animals, unlike other members of the genus, and is most frequently associated with reptiles.
Salmonella enterica is a rod-shaped, flagellate, facultative aerobic, Gram-negative bacterium and a species of the genus Salmonella. A number of its serovars are serious human pathogens.
Efforts to prevent the disease include the proper washing, preparation, and cooking of food.Mild disease typically does not require specific treatment. More significant cases may require treatment of electrolyte problems and intravenous fluid replacement. In those at high risk or in whom the disease has spread outside the intestines, antibiotics are recommended.
Intravenous therapy (IV) is a therapy that delivers liquid substances directly into a vein. The intravenous route of administration can be used for injections or infusions. Intravenous infusions are commonly referred to as drips. The intravenous route is the fastest way to deliver medications and fluid replacement throughout the body, because the circulation carries them. Intravenous therapy may be used for fluid replacement, to correct electrolyte imbalances, to deliver medications, and for blood transfusions.
Salmonellosis is one of the most common causes of diarrhea globally.In 2015, 90,300 deaths occurred from nontyphoidal salmonellosis, and 178,000 deaths from typhoidal salmonellosis. In the United States, about 1.2 million cases and 450 deaths occur from nontyphoidal salmonellosis a year. In Europe, it is the second most common foodborne disease after campylobacteriosis.
Campylobacteriosis is an infection by the Campylobacter bacterium, most commonly C. jejuni. It is among the most common bacterial infections of humans, often a foodborne illness. It produces an inflammatory, sometimes bloody, diarrhea or dysentery syndrome, mostly including cramps, fever and pain.
After a short incubation period of a few hours to one day, the bacteria multiply in the small intestine, causing an intestinal inflammation (enteritis). Most people with salmonellosis develop diarrhea, fever, vomiting, and abdominal cramps 12 to 72 hours after infection.Diarrhea is often watery and non-bloody but may be mucoid and bloody. In most cases, the illness lasts four to seven days, and does not require treatment. In some cases, though, the diarrhea may be so severe that the patient becomes dangerously dehydrated and must be hospitalized. At the hospital, the patient may receive fluids intravenously to treat the dehydration, and may be given medications to provide symptomatic relief, such as fever reduction. In severe cases, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites, and can cause death, unless the person is treated promptly with antibiotics.
The small intestine or small bowel is the part of the gastrointestinal tract between the stomach and the large intestine, and is where most of the end absorption of food takes place. The small intestine has three distinct regions – the duodenum, jejunum, and ileum. The duodenum is the shortest part of the small intestine and is where preparation for absorption begins. It also receives bile and pancreatic juice through the pancreatic duct, controlled by the sphincter of Oddi. The primary function of the small intestine is the absorption of nutrients and minerals from food, using small finger-like protrusions called villi.
Enteritis is inflammation of the small intestine. It is most commonly caused by food or drink contaminated with pathogenic microbes, such as serratia, but may have other causes such as NSAIDs, cocaine, radiation therapy as well as autoimmune conditions like Crohn's disease and coeliac disease. Symptoms include abdominal pain, cramping, diarrhoea, dehydration, and fever.
In otherwise healthy adults, the symptoms can be mild. Normally, no sepsis occurs, but it can occur exceptionally as a complication in the immunocompromised. However, in people at risk such as infants, small children, and the elderly, Salmonella infections can become very serious, leading to complications. In infants, dehydration can cause a state of severe toxicity. Extraintestinal localizations are possible, especially Salmonella meningitis in children, osteitis, etc. Children with sickle-cell anemia who are infected with Salmonella may develop osteomyelitis. Treatment of osteomyelitis, in this case, will be to use fluoroquinolones (ciprofloxacin, levofloxacin, etc., and nalidixic acid).
Sepsis is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. Common signs and symptoms include fever, increased heart rate, increased breathing rate, and confusion. There may also be symptoms related to a specific infection, such as a cough with pneumonia, or painful urination with a kidney infection. In the very young, old, and people with a weakened immune system, there may be no symptoms of a specific infection and the body temperature may be low or normal, rather than high. Severe sepsis is sepsis causing poor organ function or insufficient blood flow. Insufficient blood flow may be evident by low blood pressure, high blood lactate, or low urine output. Septic shock is low blood pressure due to sepsis that does not improve after fluid replacement.
In physiology, dehydration is a deficit of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mild dehydration can also be caused by immersion diuresis, which may increase risk of decompression sickness in divers.
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell (cytotoxicity) or an organ such as the liver (hepatotoxicity). By extension, the word may be metaphorically used to describe toxic effects on larger and more complex groups, such as the family unit or society at large. Sometimes the word is more or less synonymous with poisoning in everyday usage.
Those whose only symptom is diarrhea usually completely recover, but their bowel habits may not return to normal for several months.
Typhoid fever occurs when Salmonella bacteria enter the lymphatic system and cause a systemic form of salmonellosis. Endotoxins first act on the vascular and nervous apparatus, resulting in increased permeability and decreased tone of the vessels, upset thermal regulation, vomiting, and diarrhea. In severe forms of the disease, enough liquid and electrolytes are lost to upset the fluid balance, cause an electrolyte imbalance, decrease the circulating blood volume and arterial pressure, and cause hypovolemic shock. Septic shock may also develop. Shock of mixed character (with signs of both hypovolemic and septic shock) are more common in severe salmonellosis. Oliguria and azotemia develop in severe cases as a result of renal involvement due to hypoxia and toxemia.
Salmonellosis is associated with later irritable bowel syndromeand inflammatory bowel disease. Evidence however does not support it being a direct cause of the latter.
A small number of people afflicted with salmonellosis experience reactive arthritis, which can last months or years and can lead to chronic arthritis.In sickle-cell anemia, osteomyelitis due to Salmonella infection is much more common than in the general population. Though Salmonella infection is frequently the cause of osteomyelitis in people with sickle-cell, it is not the most common cause, which is Staphylococcus infection.
Those infected may become asymptomatic carriers, but this is relatively uncommon, with shedding observed in only 0.2 to 0.6% of cases after a year.
Salmonella bacteria can survive for some time without a host; they are frequently found in polluted water, with contamination from the excrement of carrier animals being particularly important.
The European Food Safety Authority highly recommends that when handling raw turkey meat, consumers and people involved in the food supply chain should pay attention to personal and food hygiene.
An estimated 142,000 Americans are infected each year with Salmonella Enteritidis from chicken eggs,and about 30 die. The shell of the egg may be contaminated with Salmonella by feces or environment, or its interior (yolk) may be contaminated by penetration of the bacteria through the porous shell or from a hen whose infected ovaries contaminate the egg during egg formation.
Nevertheless, such interior egg yolk contamination is theoretically unlikely.Even under natural conditions, the rate of infection was very small (0.6% in a study of naturally contaminated eggs and 3.0% among artificially and heavily infected hens ).
The US Food and Drug Administration (FDA) has published guidelines to help reduce the chance of food-borne salmonellosis. 145–165 °F (63–74 °C), and liquids such as soups or gravies should be boiled when reheating. Freezing kills some Salmonella, but it is not sufficient to reliably reduce them below infectious levels. While Salmonella is usually heat-sensitive, it acquires heat-resistance in high-fat environments such as peanut butter.Food must be cooked to
Antibodies against nontyphoidal Salmonella were first found in Malawi children in research published in 2008. The Malawian researchers identified an antibody that protects children against bacterial infections of the blood caused by nontyphoidal Salmonella. A study at Queen Elizabeth Hospital in Blantyre found that children up to two years old develop antibodies that aid in killing the bacteria. This could lead to a possible Salmonella vaccine for humans.
A 2014 study tested a vaccine on chickens which offered efficient protection against salmonellosis.
Vaccination of chickens against Salmonella essentially wiped out the disease in the United Kingdom. A similar approach was considered in the United States, but the Food and Drug Administration decided not to mandate vaccination of hens.
Since 2011, Denmark has had zero cases of human salmonella poisoning.The country eradicated salmonella without vaccines and antibiotics by focusing on eliminating the infection from "breeder stocks", implementing various measures to prevent infection, and taking a zero-tolerance policy towards salmonella in chickens.
Electrolytes may be replenished with oral rehydration supplements (typically containing salts sodium chloride and potassium chloride).
Appropriate antibiotics, such as ceftriaxone, may be given to kill the bacteria, but are not necessary in most cases.Azithromycin has been suggested to be better at treating typhoid in resistant populations than both fluoroquinolone drugs and ceftriaxone. There are recommendations on choice of antibiotic to avoid promoting antibiotic resistance.
About 142,000 people in the United States are infected each year with Salmonella Enteritidis from chicken eggs, and about 30 die.
In 2010, an analysis of death certificates in the United States identified a total of 1,316 Salmonella-related deaths from 1990 to 2006. These were predominantly among older adults and those who were immunocompromised.The U.S. government reported as many as 20% of all chickens were contaminated with Salmonella in the late 1990s, and 16.3% were contaminated in 2005.
The United States has struggled to control salmonella infections, with the rate of infection rising from 2001 to 2011. In 1998, the USDA moved to close plants if salmonella was found in excess of 20 percent, which was the industry’s average at the time, for three consecutive tests.Texas-based Supreme Beef Processors, Inc. sued on the argument that Salmonella is naturally occurring and ultimately prevailed when a federal appeals court affirmed a lower court. These issues were highlighted in a proposed Kevin's Law (formally proposed as the Meat and Poultry Pathogen Reduction and Enforcement Act of 2003), of which components were included the Food Safety Modernization Act passed in 2011, but that law applies only to the FDA and not the USDA. The USDA proposed a regulatory initiative in 2011 to Office of Management and Budget.
An outbreak of salmonellosis started in Northern Europe in July 2012, caused by Salmonella thompson. The infections were linked to smoked salmon from the manufacturer Foppen, where the contamination had occurred. Most infections were reported in the Netherlands; over 1060 infections with this subspecies and four fatalities were confirmed.
A case of widespread infection was detected mid-2012 in seven EU countries. Over 400 people had been infected with Salmonella enterica serovar Stanley (S. Stanley) that usually appears in the regions of Southeast Asia. After several DNA analyses seemed to point to a specific Belgian strain, the "Joint ECDC/E FSA Rapid Risk Assessment" report detected turkey production as the source of infection.
In Germany, food poisoning infections must be reported.Between 1990 and 2005, the number of officially recorded cases decreased from about 200,000 to about 50,000.
In March 2007, around 150 people were diagnosed with salmonellosis after eating tainted food at a governor's reception in Krasnoyarsk, Russia. Over 1,500 people attended the ball on March 1 and fell ill as a consequence of ingesting Salmonella-tainted sandwiches.
About 150 people were sickened by Salmonella-tainted chocolate cake produced by a major bakery chain in Singapore in December 2007.
Both salmonellosis and the microorganism genus Salmonella derive their names from a modern Latin coining after Daniel E. Salmon (1850–1914), an American veterinary surgeon. He had help from Theobald Smith, and together they found the bacterium in pigs.
Salmonella enterica was possibly the cause of the 1576 cocliztli epidemic in New Spain.
The "Four-inch regulation" or "Four-inch law" is a colloquial name for a regulation issued by the U.S. FDA in 1975, restricting the sale of turtles with a carapace length less than four inches (10 cm).
The regulation was introduced, according to the FDA, "because of the public health impact of turtle-associated salmonellosis". Cases had been reported of young children placing small turtles in their mouths, which led to the size-based restriction.
Zoonoses are infectious diseases caused by bacteria, viruses and parasites that spread between animals and humans.
Shigellosis is an infection of the intestines caused by Shigella bacteria. Symptoms generally start one to two days after exposure and include diarrhea, fever, abdominal pain, and feeling the need to pass stools even when the bowels are empty. The diarrhea may be bloody. Symptoms typically last five to seven days. Complications can include reactive arthritis, sepsis, seizures, and hemolytic uremic syndrome.
In cooking, coddled eggs are eggs that are gently or lightly cooked in water just below boiling temperature in or out of the shell or other container. They can be partially cooked, mostly cooked, or hardly cooked at all. Poached eggs are a type of coddled egg cooked in water.
Egg white is the clear liquid contained within an egg. In chickens it is formed from the layers of secretions of the anterior section of the hen's oviduct during the passage of the egg. It forms around fertilized or unfertilized egg yolks. The primary natural purpose of egg white is to protect the yolk and provide additional nutrition for the growth of the embryo . Egg white consists primarily of about 90% water into which about 10% proteins are dissolved. Unlike the yolk, which is high in lipids (fats), egg white contains almost no fat, and carbohydrate content is less than 1%. Egg whites contain about 56% of the protein in the egg. Egg white has many uses in food and also many other uses.
Foodborne illness is any illness resulting from the food spoilage of contaminated food, pathogenic bacteria, viruses, or parasites that contaminate food, as well as toxins such as poisonous mushrooms and various species of beans that have not been boiled for at least 10 minutes.
Campylobacter jejuni is one of the most common causes of food poisoning in Europe and in the United States. The vast majority of cases occur as isolated events, not as part of recognized outbreaks. Active surveillance through the Foodborne Diseases Active Surveillance Network (FoodNet) indicates that about 14 cases are diagnosed each year for each 100,000 persons in the population. The European Food Safety Authority estimated in 2011 that there are approximately nine million cases of human campylobacteriosis per year in the European Union.
Gastroenteritis, also known as infectious diarrhea, is inflammation of the gastrointestinal tract—the stomach and small intestine. Symptoms may include diarrhea, vomiting and abdominal pain. Fever, lack of energy and dehydration may also occur. This typically lasts less than two weeks. It is not related to influenza, though it has been called the "stomach flu".
Listeriosis is a bacterial infection most commonly caused by Listeria monocytogenes, although L. ivanovii and L. grayi have been reported in certain cases. Listeriosis can cause severe illness, including severe sepsis, meningitis, or encephalitis, sometimes resulting in lifelong harm and even death. Those at risk of severe illness are the elderly, unborn babies, newborns and those who are immunocompromised. In pregnant women it may cause stillbirth or spontaneous abortion, and preterm birth is common. Listeriosis may cause mild, self-limiting gastroenteritis and fever in anyone.
Forced molting, sometimes known as induced molting, is the practice by some poultry industries of artificially provoking a flock to molt simultaneously, typically by withdrawing food for 7–14 days and sometimes also withdrawing water for an extended period. Forced molting is usually implemented when egg-production is naturally decreasing toward the end of the first egg-laying phase. During the forced molt, the birds cease producing eggs for at least two weeks, which allows the bird's reproductive tracts to regress and rejuvenate. After the molt, the hen's egg production rate usually peaks slightly lower than the previous peak, but egg quality is improved. The purpose of forced molting is therefore to increase egg production, egg quality, and profitability of flocks in their second or subsequent laying phases, by not allowing the hen's body the necessary time to rejuvenate during the natural cycle of feather replenishment.
Paratyphoid fever, also known simply as paratyphoid, is a bacterial infection caused by one of the three types of Salmonella enterica. Symptoms usually begin 6–30 days after exposure and are the same as those of typhoid fever. Often, a gradual onset of a high fever occurs over several days. Weakness, loss of appetite, and headaches also commonly occur. Some people develop a skin rash with rose-colored spots. Without treatment, symptoms may last weeks or months. Other people may carry the bacteria without being affected; however, they are still able to spread the disease to others. Both typhoid and paratyphoid are of similar severity. Paratyphoid and typhoid fever are types of enteric fever.
Exogenous bacteria are microorganisms introduced to closed biological systems from the external world. They exist in aquatic and terrestrial environments, as well as the atmosphere. Microorganisms in the external environment have existed on Earth for 3.5 billion years. Exogenous bacteria can be either benign or pathogenic. Pathogenic exogenous bacteria can enter a closed biological system and cause disease such as Cholera, which is induced by a waterborne microbe that infects the human intestine. Exogenous bacteria can be introduced into a closed ecosystem as well, and have mutualistic benefits for both the microbe and the host. A prominent example of this concept is bacterial flora, which consists of exogenous bacteria ingested and endogenously colonized during the early stages of life. Bacteria that are part of normal internal ecosystems, also known as bacterial flora, are called Endogenous Bacteria. A significant amount of prominent diseases are induced by exogenous bacteria such as gonorrhea, meningitis, tetanus, and syphilis. Pathogenic exogenous bacteria can enter a host via cutaneous transmission, inhalation, and consumption.
Some eggs are laid by female animals of many different species, including birds, reptiles, amphibians, mammals, and fish, and have been eaten by humans for thousands of years. Bird and reptile eggs consist of a protective eggshell, albumen, and vitellus, contained within various thin membranes. The most commonly consumed eggs are chicken eggs. Other poultry eggs including those of duck and quail also are eaten. Fish eggs are called roe and caviar.
Pasteurized eggs are eggs that have been pasteurized in order to reduce the risk of food-borne illness in dishes that are not cooked or are only lightly cooked. They may be sold as liquid egg products or pasteurized in the shell.
Histomoniasis is a commercially important disease of poultry, particularly of chickens and turkeys, due to parasitic infection of a protozoan, Histomonas meleagridis. The protozoan is transmitted to the bird by the nematode parasite Heterakis gallinarum. H. meleagridis resides within the eggs of H. gallinarum, so birds ingest the parasites along with contaminated soil or food. Earthworms can also act as a paratenic host.
In general, the United States alone experiences 1 million cases of salmonellosis per year. In Europe, although there are around 100,000 incidents of salmonellosis reported annually, there has been a steady decrease in cases over the past four years. The exact number of those infected is impossible to know as not all cases are reported. Of these reported cases, some can be classified as foodborne disease outbreaks by the Center for Disease Control and Prevention (CDC) if "two or more people get the same illness from the same contaminated food or drink" or zoonotic outbreaks if "two or more people get the same illness from the same pet or other animal". In 2012, the various strains or serotypes of the Salmonella bacteria, related to the outbreaks in the United States, infected over 1800 people and killed seven. In Europe, the European Centre for Disease Prevention and Control (ECDC) reported 91,034 cases of Salmonella infection with 65,317 cases related to the 2012 outbreaks. Of those 65,317 cases, there were 61 deaths.
Salmonellosis annually causes, per CDC estimation, about 1.2 million illnesses, 23,000 hospitalizations, and 450 deaths in the United States every year.
The U.S. Food and Drug Administration (FDA) estimates that 142,000 illnesses each year are caused by consuming eggs contaminated with Salmonella.
Among them is a final rule, issued by the FDA, to reduce the contamination in eggs. About 142,000 Americans are infected each year with Salmonella enteritidis from eggs, the result of an infected hen passing along the bacterium. About 30 die.
Eggs can be contaminated on the outer shell surface and internally. Internal contamination can be the result of penetration through the eggshell or by direct contamination of egg contents before oviposition, originating from infection of the reproductive organs. Once inside the egg, the bacteria need to cope with antimicrobial factors in the albumen and vitelline membrane before migration to the yolk can occur
Salmonella enteritidis can contaminate the contents of clean, intact shell eggs as a result of infections of the reproductive tissue of laying hens. The principal site of infection appears to be the upper oviduct. In egg contents, the most important contamination sites are the outside of the vitelline membrane or the albumen surrounding it. In fresh eggs, only a few salmonellae are present. As albumen is an iron-restricted environment, growth only occurs with storage-related changes to vitelline membrane permeability, which allows salmonellae to invade yolk contents.
Normally, the oviduct of the hen is sterile and therefore the shell and internal contents of the egg are also free of microorganisms (10,16). In some instances, however, the ovaries and oviduct may be infected with Salmonella and these may be deposited inside the egg (12). More frequently, however, the egg becomes contaminated after it is laid.
when hens were artificially infected to test for transmission rate to yolks: "Mature laying hens were inoculated intravenously with 106 colony-forming units of Salmonella enteritidis, Salmonella typhimurium, Salmonella infantis, Salmonella hadar, Salmonella heidelberg, or Salmonella montevideo to cause the systemic infection. Salmonella Enteritidis was recovered from three yolks of the laid eggs (7.0%), suggesting egg contamination from the transovarian transmission of S. enteritidis."
In this study, egg yolks were infected at the surface of the yolk (vitelline membrane) to determine the percentage of yolk contamination (a measure used to determine egg contamination resistance, with numbers lower than 95% indicating increasing resistance): Overall, the frequency of penetration of Salmonella Enteritidis into the yolk contents of eggs from individual lines of hens ranged from 30 to 58% and the mean concentration of Salmonella Enteritidis in yolk contents after incubation ranged from 0.8 to 2.0 log10 cfu/mL.
The migration of the bacterium into the nutritionally rich yolk is constrained by the lysozyme loaded vitelline membrane, and would need warm enough storage conditions within days and weeks. The high concentration on of antibodies of the yolk does not inhibit the Salmonella multiplication. Only seldom does transovarian contamination of the developing eggs with S. enteritidis make this bacterium occur in laid eggs, because of the bactericidal efficacy of the antimicrobial peptides
Over 5700 hens eggs from 15 flocks naturally infected with Salmonella enteritidis were examined individually for the presence of the organism in either egg contents or on shells. Thirty-two eggs (0·6%) were positive in the contents. In the majority, levels of contamination were low.
when hens are artificially infected with unrealistically large doses (according to the author): In the present study, groups of laying hens were experimentally infected with large oral doses of Salmonella Heidelberg, Salmonella Enteritidis phage type 13a, or Salmonella Enteritidis phage type 14b. For all of these isolates, the overall frequency of ovarian colonization (34.0%) was significantly higher than the frequency of recovery from either the upper (22.9%) or lower (18.1%) regions of the oviduct. No significant differences were observed between the frequencies of Salmonella isolation from egg yolk and albumen (4.0% and 3.3%, respectively).
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