Nontyphoid salmonella infections:

Nontyphoid salmonella infections: 

Nontyphoidal Salmonella infections are common and remain a significant public health problem in the US. Many serotypes of Salmonella have been given names and are referred to informally as if they were separate species even though they are not. Most nontyphoidal Salmonella infections are caused by S. enterica subspecies enterica serotype Enteritidis, S. Typhimurium, S. Newport, S. Heidelberg, and S. Javiana.

Human disease occurs by direct and indirect contact with numerous species of infected animals, the foodstuffs derived from them, and their excreta. Contaminated meat, poultry, raw milk, eggs, egg products, and water are common sources of Salmonella. Other reported sources include infected pet turtles and reptiles, carmine red dye, and contaminated marijuana.

Cause and transmission 

• Salmonellosis is a disease caused by the bacteria Salmonella.
• Salmonella bacteria are widely distributed in domestic and wild animals. They are prevalent in food animals such as poultry, pigs, and cattle; and in pets, including cats, dogs, birds, and reptiles such as turtles.
• Salmonella can pass through the entire food chain from animal feed, primary production, and all the way to households or food-service establishments and institutions.
• Salmonellosis in humans is generally contracted through the consumption of contaminated food of animal origin (mainly eggs, meat, poultry, and milk), although other foods, including green vegetables contaminated by manure, have been implicated in its transmission.
• Person-to-person transmission can also occur through the faecal-oral route.
• Human cases also occur where individuals have contact with infected animals, including pets. These infected animals often do not show signs of disease.

Symptoms 

Salmonella infection may manifest as:

• Gastroenteritis
• Enteric fever
• Bacteremia
• Focal disease

Gastroenteritis usually starts 12 to 48 hours after ingestion of organisms, with nausea and cramping abdominal pain followed by diarrhea, fever, and sometimes vomiting. Usually, the stool is watery but may be a pastelike semisolid. Rarely, mucus or blood is present. The disease is usually mild, lasting 1 to 4 days. Occasionally, a more severe, protracted illness occurs. About 10 to 30% of adults develop reactive arthritis weeks to months after diarrhea stops. This disorder causes pain and swelling, usually in the hips, knees, and Achilles tendon.

Enteric fever is a term often used interchangeably with typhoid fever. Enteric fever typically refers to a form of typhoid caused by nontyphoidal Salmonella infections caused by S. enterica subspecies; it is characterized by fever, prostration, and septicemia.

Bacteremia is relatively uncommon in patients with gastroenteritis, except in infants and older people. However, S. Choleraesuis, S. Typhimurium, and S. Heidelberg, among others, can cause a sustained and frequently lethal bacteremic syndrome lasting ≥ 1 week, with prolonged fever, headache, malaise, and chills but rarely diarrhea. Sustained bacteremia suggests endovascular infection, such endocarditis or infection of an abdominal aortic aneurysm, which can occur as a complication of Salmonella bacteremia. Patients may have recurrent episodes of bacteremia or other invasive infections (eg, infectious arthritis) due to Salmonella. Bacteremia is more likely to occur in immunologically compromised patients (eg, those with HIV/AIDS) and in patients with a hemolytic condition (eg, sickle cell anemia, malaria, Oroya fever), who are also more likely to develop a focal infection, such as infectious arthritis, osteomyelitis, pneumonia, endarteritis (eg, infected aortic aneurysm), endocarditis, urinary tract infection, cholangitis, and meningitis. Recurrent or multiple episodes of Salmonella infection in a patient without other risk factors should prompt HIV testing.

Focal Salmonella infection can occur with or without sustained bacteremia, causing pain in or referred from the involved organ—the gastrointestinal tract (liver, gallbladder, appendix), endothelial surfaces (eg, atherosclerotic plaques, ileofemoral or aortic aneurysms, heart valves), pericardium, meninges, lungs, joints, bones, genitourinary tract, or soft tissues. Preexisting solid tumors are occasionally seeded and develop abscesses that may, in turn, become a source of Salmonella bacteremia. S. Choleraesuis and S. Typhimurium are the most common causes of focal infection.

Diagnosis

Culturing organisms continues to be the mainstay of clinical diagnostic testing for nontyphoidal Salmonella infection. Approximately 90% of isolates are obtained from routine stool culture, but isolates can also be obtained from other sites of infection if present, including blood, urine, abscesses, and cerebrospinal fluid. Although culture-independent diagnostic tests are used increasingly by clinical laboratories to diagnose Salmonella infection, isolates are necessary for serotyping and antimicrobial susceptibility testing. Serologic testing to detect infection with Salmonella is not advised.

Most states mandate that Salmonella isolates or clinical material be submitted to the local or state public health laboratory. To understand submission requirements in a particular state, clinical laboratories are advised to review the disease reporting and mandatory isolate submission regulations of that state and to contact their local public health department with any questions. Salmonellosis is a nationally notifiable disease.

Note: Rate under the appropriate body system any residual disability of infection, which includes, but is not limited to, reactive arthritis.