Yersinia enterocolitica Food Poisoning (Yersiniosis)

Yersinia enterocolitica is a type of bacteria that causes yersiniosis, a foodborne disease that affects the intestines and can lead to diarrhea, fever, and abdominal pain. It belongs to the family Yersiniaceae, which also includes Yersinia pestis, the causative agent of plague.

Yersinia enterocolitica is a gram-negative, non-spore forming bacillus or coccobacillus that can grow on common culture media. It is motile at lower temperatures (22–29 °C), but becomes nonmotile at normal human body temperature (37 °C). It is also oxidase negative, catalase positive, and facultative anaerobic.

Yersinia enterocolitica has different strains that vary in their pathogenicity and serotype. The most common serotype associated with human infection is Y. enterocolitica bioserotype 4/O:3. Some strains of Y. enterocolitica can produce a heat-stable enterotoxin (Yst) that causes fluid secretion in the intestines. Other strains have a virulence plasmid (pYV) that encodes factors for attachment, invasion, and survival within host cells.

Yersinia enterocolitica is mainly transmitted by eating raw or undercooked pork contaminated with the bacterium, but other animals such as cattle, sheep, goats, rodents, and poultry can also carry it. Vegetables, milk and milk products, water, and sewage can also be sources of contamination. The infection is more common in children than adults, and more prevalent in winter than summer.

Yersinia enterocolitica is a bacterium that can cause food poisoning when people eat contaminated food. The main sources of contamination are animal foods such as meat, poultry, or unpasteurized milk, and seafood from polluted water. Yersinia bacteria are found in soil and water and can be transferred to food through cross-contamination during food handling, processing, or storage.

One of the most important reservoirs of Yersinia enterocolitica is pigs, which can carry the bacterium in their oral cavity, intestines, feces, and lymph nodes. Other animals such as birds, beavers, cats, and dogs can also harbor Yersinia enterocolitica and contaminate the environment. Therefore, foods that come into contact with animal wastes or contaminated soil or water are at risk of being infected with Yersinia enterocolitica.

Some of the foods that have been associated with Yersinia enterocolitica outbreaks include chitterlings (pig intestines), pork, tofu, lettuce, carrots, milk, and cheese. These foods may be contaminated at the farm, slaughterhouse, processing plant, retail store, or home. For example, chitterlings may be contaminated during slaughtering or cleaning, pork may be contaminated during cutting or grinding, and milk may be contaminated during milking or pasteurization.

Yersinia enterocolitica is a psychrotrophic bacterium, which means it can grow at refrigeration temperatures. Therefore, storing food at low temperatures may not prevent the growth of Yersinia enterocolitica. However, Yersinia enterocolitica is heat-sensitive and can be easily destroyed by cooking food to a safe internal temperature.

Yersinia enterocolitica food poisoning, also known as yersiniosis, can cause a variety of symptoms depending on the age and health status of the infected person. The symptoms usually appear within 24 to 30 hours after eating contaminated food, but they can also take up to 10 days to develop. The most common symptoms are:

• Diarrhea, which may be bloody or watery
• Abdominal pain and cramps, especially in the lower right side
• Fever and chills
• Nausea and vomiting
• Headache and malaise

Some people may experience more severe complications, such as:

• Reactive arthritis, which is a type of joint inflammation that can affect the knees, ankles, wrists, or fingers. It usually occurs within a month after the infection and may last for several months.
• Erythema nodosum, which is a type of skin rash that causes red, tender bumps on the legs or arms. It usually resolves within a few weeks.
• Enterocolitis, which is a severe inflammation of the colon and small intestine that can cause bloody diarrhea, dehydration, and weight loss.
• Mesenteric lymphadenitis, which is an inflammation of the lymph nodes in the abdomen that can mimic appendicitis. It can cause severe abdominal pain, fever, and vomiting.
• Terminal ileitis, which is an inflammation of the end of the small intestine that can cause chronic diarrhea, abdominal pain, and weight loss.

In rare cases, Yersinia enterocolitica can spread to other parts of the body and cause life-threatening infections, such as:

• Septicemia, which is a blood infection that can cause shock and organ failure.
• Pneumonia, which is a lung infection that can cause breathing difficulties and chest pain.
• Meningitis, which is an infection of the membranes covering the brain and spinal cord that can cause headache, stiff neck, confusion, and seizures.
• Endocarditis, which is an infection of the heart valves that can cause heart murmurs, chest pain, and heart failure.

The symptoms of yersiniosis may vary depending on the strain of Yersinia enterocolitica involved. The most common strain associated with human infections is bioserotype 4/O:3. Other strains may cause different or milder symptoms.

The duration of yersiniosis may also vary depending on the severity of the infection and the treatment received. In most cases, the symptoms resolve within one to two weeks without any specific treatment. However, some people may have persistent or recurrent symptoms for several months or years.

Yersiniosis can be diagnosed by testing a stool sample for the presence of Yersinia enterocolitica bacteria or their toxins. Blood tests may also be done to check for antibodies or signs of infection. Imaging tests such as ultrasound or CT scan may be needed to rule out other causes of abdominal pain or complications.

Yersiniosis can be prevented by avoiding eating raw or undercooked pork products or other foods that may be contaminated with Yersinia enterocolitica. Proper cooking and handling of food can kill the bacteria and prevent cross-contamination. Good hygiene practices such as washing hands before and after handling food or animals can also reduce the risk of infection.

Yersiniosis is usually a self-limiting disease that does not require any specific treatment. However, in some cases, antibiotics may be prescribed to treat severe or complicated infections. Oral rehydration therapy may also be needed to replace fluids and electrolytes lost due to diarrhea. Pain relievers and anti-inflammatory drugs may help to ease the symptoms of arthritis or erythema nodosum.

Yersiniosis is not a common disease in most parts of the world, but it can cause significant morbidity and mortality in some regions. It is important to be aware of the symptoms and sources of Yersinia enterocolitica food poisoning and seek medical attention if needed. With proper prevention and treatment, most people can recover from yersiniosis without any long-term complications.

Yersinia enterocolitica is transmitted orally, and about 10⁷ to 10⁹ cells are required to cause an infection. After ingestion, the bacteria travel through the stomach and reach the small intestine, where they colonize in the terminal ileum and proximal colon. They also penetrate inside the mucosal layer of the intestine and infect the tissue as the strains of pathogenic Yersinia enterocolitica can resist non-specific immune responses.

Y. enterocolitica contains a 70-kb virulence plasmid (pYV) that helps organisms to replicate within lymphoid tissue. The pYV genes are influenced by the optimum temperature at 37°C and low calcium concentration. The attachment invasion locus (Ail) protein of the pathogen is involved in the attachment and invasion to host cells and protects bacteria against host immune responses. YadA (Yersinia adhesion A) promotes replication of bacteria in Payer’s patches and forms abscesses causing inflammation of joints.

Bacteria are then spread from Payer’s patches to the liver, spleen, lungs, and lymph nodes causing characteristic lymphadenitis. A heat-stable Yst enterotoxin promotes fluid secretion and the membrane-bound guanylate cyclase is stimulated by three components of Yst (Yst-A, Yst-B, and Yst-C). These components activate the intracellular cyclic guanosine monophosphate (cGMP) and cGMP-dependent protein kinase resulting in inhibition of Na+ absorption and stimulating Cl– secretion.

The infection caused by Yersinia enterocolitica can mimic appendicitis, as the bacteria can inflame the appendix and cause abdominal pain. The infection can also trigger reactive arthritis, a condition that causes joint pain, swelling, and stiffness. In rare cases, the infection can lead to complications such as septicemia, pneumonia, meningitis, and endocarditis.

Yersinia enterocolitica food poisoning, or yersiniosis, is a global public health problem that affects both developed and developing countries. The incidence and prevalence of yersiniosis vary widely depending on the geographic region, the surveillance system, the diagnostic methods, and the exposure to risk factors.

According to the CDC, Y. enterocolitica causes almost 117,000 illnesses, 640 hospitalizations, and 35 deaths in the United States every year. Children are infected more often than adults, and the infection is more common in the winter. The disease is not reportable in some states, which may underestimate its true burden.

In Europe, yersiniosis is the fourth most common zoonotic disease after campylobacteriosis, salmonellosis, and shigellosis. In 2019, more than 7,000 cases were reported in the European Union, with a notification rate of 1.7 cases per 100,000 population. The highest rates were observed in Finland (10.6), Lithuania (10.4), and Estonia (5.6). The most common serotype of Y. enterocolitica associated with human infection is bioserotype 4/O:3.

In Asia, yersiniosis is less frequently reported, but some outbreaks have been documented in Japan, China, and Malaysia. The sources and serotypes of Y. enterocolitica vary depending on the local food habits and environmental conditions.

The main mode of transmission of Y. enterocolitica is through the consumption of contaminated food or water. Pigs are reported to be the primary reservoir of Y. enterocolitica, and other sources include food animals, wild animals, sewage, and soil. The organism can survive and grow at low temperatures, which poses a challenge for food safety.

The most common foods implicated in yersiniosis outbreaks are raw or undercooked pork products, such as chitterlings (pig intestines), sausages, ham, and bacon. Other foods that have been linked to yersiniosis include raw milk and dairy products, tofu, vegetables, and salads. Cross-contamination between raw and cooked foods can also occur during food preparation or storage.

Person-to-person transmission of Y. enterocolitica is possible but rare. It can occur through fecal-oral contact or through contact with infected animals or their feces. People who are at higher risk of developing severe complications from yersiniosis include infants, elderly people, pregnant women, and immunocompromised individuals.

Detecting Yersinia enterocolitica in food samples is challenging due to its low concentration, heterogeneous distribution, and similarity to other bacteria. Therefore, various methods have been developed and applied to identify and quantify this pathogen.

• Culture methods involve the enrichment of food samples in selective broth media, followed by isolation and identification of Y. enterocolitica on selective agar media. The most commonly used selective media are cefsulodin-irgasan-novobiocin (CIN) agar and MacConkey agar. However, these methods are time-consuming, labor-intensive, and may not differentiate pathogenic from non-pathogenic strains.
• Serological methods use specific antibodies to detect the antigens of Y. enterocolitica in food samples. These methods include agglutination tests, indirect immunofluorescence assays, and enzyme-linked immunosorbent assays (ELISAs). However, these methods may have low sensitivity and specificity, and may cross-react with other bacteria.
• Molecular methods use nucleic acid amplification techniques to detect the genes of Y. enterocolitica in food samples. These methods include polymerase chain reaction (PCR), real-time PCR, multiplex PCR, loop-mediated isothermal amplification (LAMP), and DNA microarrays. These methods are rapid, sensitive, specific, and can differentiate pathogenic from non-pathogenic strains. However, these methods may require expensive equipment and skilled personnel, and may be affected by inhibitors present in food samples.

Among these methods, molecular methods are considered the most promising for the detection of Y. enterocolitica in food samples due to their advantages over culture and serological methods. However, further research and validation are needed to optimize these methods and make them more accessible and reliable for routine use.

Yersiniosis is usually a mild and self-limiting infection that does not require any specific treatment. However, some cases may be more severe and need medical attention. The following are some of the treatment options for yersiniosis:

• Oral rehydration therapy: This is the most important and effective treatment for yersiniosis, especially for children and elderly people who are at risk of dehydration due to diarrhea and vomiting. Oral rehydration therapy involves drinking fluids that contain water, salt, and sugar to replace the lost fluids and electrolytes. Oral rehydration solutions (ORS) are available in pharmacies or can be prepared at home by mixing 6 teaspoons of sugar and half a teaspoon of salt in one liter of clean water. ORS should be given frequently and in small amounts until the symptoms subside.
• Antibiotics: Antibiotics are not usually recommended for yersiniosis, as they may not shorten the duration of the illness and may increase the risk of developing antibiotic resistance. However, antibiotics may be prescribed in some situations, such as when the infection is severe, complicated, or involves extraintestinal organs (such as the liver, spleen, lungs, or joints). The choice of antibiotics depends on the type and severity of the infection, the age and health status of the patient, and the susceptibility of the bacteria. Some of the antibiotics that may be used for yersiniosis include aminoglycosides (such as gentamicin or amikacin), trimethoprim-sulfamethoxazole (TMP-SMZ), ciprofloxacin, doxycycline, or third-generation cephalosporins (such as ceftriaxone or cefotaxime). Antibiotics should be taken as prescribed by the doctor and for the full course of treatment to prevent relapse or resistance.
• Symptomatic treatment: This involves taking medications or other measures to relieve the symptoms of yersiniosis, such as pain, fever, or inflammation. Some of the symptomatic treatments that may be used for yersiniosis include:
  • Analgesics: These are drugs that reduce pain and inflammation. They include nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen, or acetaminophen (paracetamol). Analgesics should be taken with caution and as directed by the doctor or pharmacist, as they may have side effects such as stomach irritation, bleeding, or liver damage.
  • Antidiarrheals: These are drugs that slow down the movement of the intestines and reduce the frequency and volume of stools. They include loperamide or bismuth subsalicylate. Antidiarrheals should be used sparingly and only when necessary, as they may worsen the infection by delaying the elimination of the bacteria from the body. They should also be avoided in children under 12 years old or in patients with bloody diarrhea, fever, or signs of dehydration.
  • Probiotics: These are live microorganisms that can help restore the balance of the intestinal flora and enhance the immune system. They include yogurt, kefir, or supplements containing lactobacilli or bifidobacteria. Probiotics may help reduce the duration and severity of diarrhea and prevent secondary infections by other pathogens. However, more research is needed to confirm their effectiveness and safety for yersiniosis.

In addition to these treatments, patients with yersiniosis should rest and avoid foods that may irritate their stomach or intestines, such as spicy, fatty, or dairy products. They should also seek medical attention if their symptoms worsen or do not improve within a week, or if they develop signs of complications such as severe abdominal pain, bloody stools, high fever, jaundice, difficulty breathing, or joint swelling.

Yersiniosis is a foodborne illness caused by the bacteria Yersinia enterocolitica, which can contaminate various foods, especially raw or undercooked pork products. To prevent and control yersiniosis, the following tips can help you and your family stay healthy:

• Avoid eating raw or undercooked pork. Cook pork to a safe minimum internal temperature of 145°F (63°C) as measured by a food thermometer. Check the color and texture of the meat before eating it.
• Drink only pasteurized milk and milk products. Pasteurization kills harmful bacteria, including Yersinia enterocolitica. Avoid consuming raw milk or products made from raw milk, such as soft cheese, ice cream, and yogurt.
• Wash hands with soap and water. Wash your hands thoroughly before eating and preparing food, after contact with animals, and after handling raw meat. This can prevent the spread of bacteria from your hands to your mouth or other surfaces.
• Use separate cutting boards and utensils for meat and other foods. Clean all cutting boards, countertops, and utensils with soap and hot water after preparing raw meat. This can prevent cross-contamination of bacteria from meat to other foods that are eaten raw or cooked lightly.
• Clean up after animals. Pick up and dispose of animal poop, especially in areas where children might play. Wash your hands with soap and water after contact with pets and other animals, their poop, or their belongings. Some animals, such as pigs, can carry Yersinia enterocolitica in their intestines without showing any signs of illness.
• Treat water if needed. If you are traveling to a place where the water supply may be unsafe, treat your water before drinking it or using it for cooking or brushing your teeth. You can boil, filter, or disinfect water to kill bacteria, including Yersinia enterocolitica.

If you suspect that you have yersiniosis, see your doctor for diagnosis and treatment. Most cases are mild and resolve on their own without antibiotics. However, some people may develop severe complications, such as reactive arthritis, skin rash, or blood infection. In these cases, antibiotics may be needed to treat the infection and prevent further complications.

By following these simple steps, you can reduce your risk of getting yersiniosis and enjoy your food safely.

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