Salmonella Infection

Salmonella is one of the most common infections in the United States. It's caused by gram-negative bacilli of the genus Salmonella, a member of the Enterobacteriaceae family. It occurs as enterocolitis, bacteremia, localized infection, typhoid fever, or paratyphoid fever. Nontyphoidal forms of salmonella infection usually produce mild to moderate illness, with low mortality. Enterocolitis and bacteremia are especially common (and more virulent) among infants, elderly people, and people already weakened by other infections, especially human immunodeficiency virus infection. Paratyphoid fever is rare in the United States.

The elderly, infants, and those with impaired immune systems may have a more severe illness. In these patients, the 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.

Causes

The most common species of Salmonella include S. typhi, which Causes typhoid fever; S. enteritidis, which usually causes enterocolitis; and S. choleresis, which commonly causes bacteremia. Of an estimated 1 ,700 serotypes of Salmonella, 10 cause the diseases most common in the United States. All 10 can survive for weeks in water, ice, sewage, and food.

Nontyphoidal salmonella infection usually follows the ingestion of contaminated or inadequately processed foods, especially eggs, chicken, turkey, and duck. Proper cooking reduces the risk of contracting salmonella infection but doesn't eliminate it. Other causes include contact with infected people or animals and ingestion of contaminated dry milk, chocolate bars, or pharmaceuticals of animal origin. Salmonella infection may occur in children under age 5 from fecaloral spread.

Typhoid fever usually results from drinking water contaminated by excretions of a carrier.

Signs and symptoms

The following are the most common symptoms of Salmonella infections. However, each individual may experience symptoms differently. Symptoms may include diarrhea, fever, and abdominal cramps 12 to 72 hours after infection.

The symptoms of Salmonella infections may resemble other conditions or medical problems. Always consult your physician for a diagnosis.

Diagnostic tests

The diagnosis of salmonellosis is confirmed by cultures of stool or blood. 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.

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.

Treatment

The type of anti-microbial agent chosen to treat typhoid fever, paratyphoid fever, or bacteremia depends on organism sensitivity. Choices include ampicillin, amoxicillin, chloramphenicol, ciprofloxacin, ceftriaxone, cefotaxime and, for the severely toxemic patient, cotrimoxazole. Localized abscesses may require surgical drainage. Enterocolitis requires a short course of antibiotics only if it causes septicemia or prolonged fever.

Symptomatic treatment includes bed rest and fluid and electrolyte replacement. Camphorated opium tincture, kaolin and pectin mixtures, diphenoxylate, codeine, or small doses of morphine can relieve diarrhea and control cramps for patients who remain active.

Prevention

• Wash your hands with soap and warm water after you have touched animal droppings, after touching a reptile or after you have touched a surface that a reptile has also touched.
• Do not consume raw or unpasteurized milk or other dairy products.
• If you have a weakened immune system, avoid contact with reptiles, baby chickens and baby ducks.
• All utensils, including cutting boards, knives, counters, etc., should be thoroughly washed after handling uncooked foods.
• Thoroughly wash hands before handling foods and between handling different food items.