Shigellosis
Shigellosis: Excerpt from Professional Guide to Diseases (Eighth Edition)
Shigellosis, also known as bacillary dysentery, is an acute intestinal infection caused by the bacteria Shigella, a short, nonmotile, gram-negative rod. Shigella can be classified into four groups, all of which may cause shigellosis: group A (S. dysenteriae), which is most common in Central America and causes particularly severe infection and septicemia; group B (S. flexneri); group C (S. boydii); and group D (S. sonnei). Typically, shigellosis causes a high fever (especially in children), acute self-limiting diarrhea with tenesmus (ineffectual straining at stool) and, possibly, electrolyte imbalance and dehydration. It's most common in children ages 1 to 4; however, many adults acquire the illness from children.
The prognosis is good. Mild infections usually subside within 10 days; severe infections may persist for 2 to 6 weeks. With prompt treatment, shigellosis is fatal in only 1% of cases, although in severe S. dysenteriae epidemic mortality may reach 8%.
Causes and incidence
Transmission occurs through the fecal-oral route; by direct contact with contaminated objects; or through ingestion of contaminated food or water. Occasionally, the housefly is a vector.
Shigellosis is endemic in North America, Europe, and the tropics. In the United States, about 18,000 cases appear annually, usually in children or in elderly, debilitated, or malnourished people. Shigellosis commonly occurs among confined populations, such as those in mental institutions or day-care centers.
Signs and symptoms
After an incubation period of 1 to 7 days (3 days is the average), Shigella organisms invade the intestinal mucosa and cause inflammation. In children, shigellosis usually produces high fever, diarrhea with tenesmus, nausea, vomiting, irritability, drowsiness, and abdominal pain and distention. Within a few days, the child's stool may contain pus, mucus, and — from the superficial intestinal ulceration typical of this infection — blood. Without treatment, dehydration and weight loss are rapid and overwhelming.
In adults, shigellosis produces sporadic, intense abdominal pain, which may be relieved at first by passing formed stools. Eventually, however, it causes rectal irritability, tenesmus and, in severe infection, headache and prostration. Stools may contain pus, mucus, and blood. Fever may be present.
Complications of shigellosis, such as electrolyte imbalance (especially hypokalemia), metabolic acidosis, and shock, aren't common but may be fatal in children and patients who are debilitated. Less common complications include conjunctivitis, iritis, arthritis, rectal prolapse, secondary bacterial infection, acute blood loss from mucosal ulcers, and toxic neuritis.
Diagnosis
CONFIRMING DIAGNOSIS Fever (in children) and diarrhea with stools containing blood, pus, and mucus point to this diagnosis; microscopic bacteriologic studies and culture help confirm it.
Microscopic examination of a fresh stool may reveal mucus, red blood cells, and polymorphonuclear leukocytes; direct immunofluorescence with specific antisera will demonstrate Shigella. Severe infection increases hemagglutinating antibodies. Sigmoidoscopy or proctoscopy may reveal typical superficial ulcerations.
Diagnosis must rule out other causes of diarrhea, such as enteropathogenic Escherichia coli infection, malabsorption diseases, and amebic or viral diseases.
Treatment
Treatment of shigellosis includes enteric precautions, low-residue diet and, most important, replacement of fluids and electrolytes with I.V. infusions of normal saline solution (with electrolytes) in sufficient quantities to maintain a urine output of 40 to 50 ml/hour. Antibiotics are of questionable value but may be used in an attempt to eliminate the pathogen and thereby prevent further spread. Ampicillin, tetracycline, or co-trimoxazole may be useful in severe cases, especially in children with overwhelming fluid and electrolyte loss. Sulfamethoxazole-trimethoprim and ciprofloxacin are also used.
Antidiarrheals that slow intestinal motility are contraindicated in shigellosis because they delay fecal excretion of Shigella and prolong fever and diarrhea. An investigational vaccine containing attenuated strains of Shigella appears promising in preventing shigellosis.
Special considerations
Supportive care can minimize complications and increase patient comfort.
❑To prevent dehydration, administer I.V. fluids as ordered. Measure intake and output (including stools) carefully.
❑Correct identification of Shigella requires examination and culture of fresh stool specimens. Therefore, hand carry specimens directly to the laboratory. Because shigellosis is suspected, include this information on the laboratory slip.
❑Use a disposable hot-water bottle to relieve abdominal discomfort, and schedule care to conserve patient strength.
❑To help prevent spread of this disease, maintain enteric precautions until microscopic bacteriologic studies confirm that the stool specimen is negative. If a risk of exposure to the patient's stool exists, put on a gown and gloves before entering the room. Keep the patient's (and your own) nails short to avoid harboring organisms. Change soiled linen promptly and store in an isolation container.
❑During shigellosis outbreaks, obtain stool specimens from all potentially infected staff, and instruct those infected to remain away from work until two stool specimens are negative.
❑Report cases to the local health department.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
More About Shigellosis
More Medical Textbooks Online about Shigellosis
Review other book chapters online related to Shigellosis:
Medical Books Excerpts
- DIARRHEA
- "Differential Diagnosis in Primary Care" (2007)
- [ read ]
- Diarrhea
- "Handbook of Signs & Symptoms (Third Edition)" (2006)
- [ read ]
- Diarrhea
- "A Pocket Manual of Differential Diagnosis" (1999)
- [ read ]
- Shigellosis
- "Professional Guide to Diseases (Eighth Edition)" (2005)
- [ read ]
- Poisoning
- "Professional Guide to Diseases (Eighth Edition)" (2005)
- [ read ]
- Diarrhea
- "Professional Guide to Signs & Symptoms (Fifth Edition)" (2006)
- [ read ]
- Diarrhea
- "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
- [ read ]
- Diarrhea
- "Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series" (2007)
- [ read ]
- Diarrhea
- "Signs & Symptoms: A 2-in-1 Reference for Nurses" (2007)
- [ read ]
- Diarrhea
- "The Diagnostic Approach to Symptoms and Signs in Pediatrics" (2006)
- [ read ]
- Diarrhea
- "Nursing: Interpreting Signs and Symptoms" (2007)
- [ read ]
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
» Next page: Poisonous snakebite (Professional Guide to Diseases (Eighth Edition))
Rate This Website
What do you think about the features of this website?
Take our user survey and have your say:
Website User Survey
Medical Tools & Articles:
Next articles:
Tools & Services:
Medical Articles:
Forums & Message Boards
- Ask or answer a question at the Boards:
