Salmonellosis
Salmonellosis: Excerpt from Handbook of Diseases
A common infection in the United States, salmonellosis is caused by gram-negative bacilli of the genus Salmonella, a member of the Enterobacteriaceae family. It occurs as enterocolitis, bacteremia, localized infection, typhoid, or paratyphoid fever. (See Clinical variants of salmonellosis, page 752.)
Nontyphoidal forms usually produce mild to moderate illness with low mortality.
Typhoid, the most severe form of salmonellosis, usually lasts from 1 to 4 weeks. Mortality is about 3% in persons who are treated and 10% in those untreated, usually as a result of intestinal perforation or hemorrhage, cerebral thrombosis, toxemia, pneumonia, or acute circulatory failure.
An attack of typhoid confers lifelong immunity, although the patient may become a carrier. Most typhoid patients are younger than age 30; most carriers are women older than age 50. Incidence of typhoid in the United States is increasing as more travelers return from endemic areas.
Enterocolitis and bacteremia are common (and more virulent) among infants, elderly people, and people already weakened by other infections; paratyphoid fever is rare in the United States.
Salmonellosis is 20 times more common in patients with acquired immunodeficiency syndrome. Features are increased incidence of bacteremia, inability to identify the infection source, and tendency of the infection to recur after therapy is stopped.
Causes
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, or food. Nontyphoidal salmonellosis generally follows the ingestion of contaminated or inadequately processed foods, especially eggs, chicken, turkey, and duck. Proper cooking reduces the risk of contracting salmonellosis.
Owning a pet turtle, lizard, iguana, or snake increases the risk factor because reptiles are carriers of salmonella. Salmonellosis may occur in children younger than age 5 from fecal-oral spread.
Typhoid results most commonly from drinking water contaminated by excretions of a carrier.
Signs and symptoms
Signs and symptoms of salmonellosis vary depending on the patient but usually include fever, abdominal pain, and severe diarrhea with enterocolitis. Headache, increasing fever, and constipation are more common with typhoidal infection.
Diagnosis
Generally, diagnosis depends on isolation of the organism in a culture, particularly blood (in typhoid, paratyphoid, and bacteremia) or feces (in enterocolitis, paratyphoid, and typhoid). Other appropriate culture specimens include urine, bone marrow, pus, and vomitus.
In endemic areas, signs and symptoms of enterocolitis allow a working diagnosis before cultures are positive. Presence of S. typhi in stools 1 or more years after treatment indicates that the patient is a carrier, which is true of 3% of patients.
Widal’s test, an agglutination reaction against somatic and flagellar antigens, may suggest typhoid with a fourfold rise in titer. However, drug use or hepatic disease can also increase these titers and invalidate test results.
Other supportive laboratory values may include transient leukocytosis during the 1st week of typhoidal salmonellosis, leukopenia during the 3rd week, and leukocytosis in local infection.
Treatment
Antimicrobial therapy for typhoid, paratyphoid, and bacteremia depends on the organism’s sensitivity. It may include amoxicillin, chloramphenicol and, if the patient is severely toxemic, cotrimoxazole, ciprofloxacin, or ceftriaxone. Localized abscesses may also need surgical drainage.
Enterocolitis requires a short course of antibiotic treatment only if it causes septicemia or prolonged fever. Other treatments include bed rest and replacement of fluids and electrolytes. Camphorated opium tincture, kaolin with pectin, diphenoxylate hydrochloride, codeine, or small doses of morphine may be necessary to relieve diarrhea and control cramps in patients who must remain active.
CLINICAL TIP: Dietary modifications may be helpful to replace electrolytes that are lost because of diarrhea. Dairy products should be restricted; instead, patients should follow the BRAT diet (bananas, rice, apples, and toast). Infants should continue to breast-feed and receive electrolyte replacement solutions.
CLINICAL TIP: A small number of persons infected with salmonellosis will develop Reiter’s syndrome, which manifests itself through joint pain, eye irritation, and painful urination and can lead to chronic arthritis. Antibiotic therapy has proven ineffective in this complication.
Special considerations
❑ Follow standard precautions. Always wash your hands thoroughly before and after any contact with the patient, and advise other hospital personnel to do the same. Teach the patient to use proper hand-washing technique, especially after defecating and before eating or handling food. Wear gloves and a gown when disposing of feces or fecally contaminated objects.
❑ Continue standard precautions until three consecutive stool cultures are negative — the first one 48 hours after antibiotic treatment ends, followed by two more at 24-hour intervals.
❑ Observe the patient closely for signs and symptoms of bowel perforation: sudden pain in the right lower abdominal quadrant, possibly after one or more rectal bleeding episodes; sudden fall in temperature or blood pressure; and rising pulse rate.
❑ During acute infection, allow the patient as much rest as possible. Raise the side rails and use other safety measures because the patient may become delirious.
❑ Accurately record intake and output. Maintain adequate I.V. hydration. When the patient can tolerate oral feedings, encourage high-calorie fluids such as milk shakes. Watch for constipation.
❑ Provide good skin and mouth care. Turn the patient frequently, and perform mild passive exercises as indicated. Apply mild heat to the abdomen to relieve cramps.
CLINICAL TIP: Don’t administer an antipyretic because it can mask fever and lead to hypothermia. Instead, to promote heat loss through the skin without causing shivering (which keeps fever high by vasoconstriction), apply tepid, wet towels (don’t use alcohol or ice) to the patient’s groin and axillae. To promote heat loss by vasodilation of peripheral blood vessels, use additional wet towels on the arms and legs, wiping with long, vigorous strokes.
❑ After draining the abscesses of a joint, provide heat, elevation, and passive range-of-motion exercises to decrease swelling and maintain mobility.
❑ If the patient has positive stool cultures on discharge, tell him to use a different bathroom than other family members if possible (while he’s taking an antibiotic), to wash his hands afterward, and to avoid preparing uncooked foods, such as salads, for family members.
❑ To prevent salmonellosis, advise prompt refrigeration of meat and cooked foods (avoid keeping them at room temperature for any prolonged period), and teach the importance of proper hand washing. Tell the patient to avoid eating raw or uncooked eggs, and to wash kitchen work surfaces immediately after they have had contact with raw meat. Advise those at high risk for contracting typhoid (laboratory workers, travelers) to seek vaccination.
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Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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