History
Populations that are at high-risk for shigellosis include the following:
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Children in daycare centers (< 5 y) and their caregivers
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Persons in custodial institutions
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International travelers
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Homosexual men
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People living in crowded conditions with poor sanitary facilities and inadequate clean water supply (eg, refugee camps, shelters for displaced people)
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People with human immunodeficiency virus (HIV) infection [18]
Symptoms include the following:
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Sudden onset of severe abdominal cramping, high-grade fever, emesis, anorexia, and large-volume watery diarrhea. Seizures may be an early manifestation.
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Abdominal pain, tenesmus, urgency, fecal incontinence, and small-volume mucoid diarrhea with frank blood (fractional stools) may subsequently occur.
Signs include the following:
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Elevated temperatures (as high as 106 º F) are documented in approximately one third of cases, and a generally toxic appearance is noticed.
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Tachycardia and tachypnea may occur secondary to fever and dehydration. Depending on the degree of dehydration, dry mucous membranes, hypotension, prolonged capillary refill time, and poor skin turgor may be present.
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Abdominal tenderness is usually central and lower, although it may be generalized.
Extra intestinal manifestations are as follows:
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CNS symptoms include severe headache, lethargy, meningismus, delirium, and convulsions lasting less than 15 minutes, especially with S dysenteriae. [19] Severe toxic encephalopathy is rare, but lethal complications occur when initial symptoms are followed by sensory obtundation, seizures, coma, and death in 6-48 hours. The pathogenesis of neurologic manifestations during shigellosis is unclear. However, data now clearly demonstrate that Stx is not responsible.
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Regarding HUS, microangiopathic hemolytic anemia, thrombocytopenia, and renal failure have been reported with S dysenteriae because of vasculopathy mediated by Stx. The principal organ affected in Stx1-mediated HUS is the kidney. This is presumed to be the consequence of the high renal blood flow and abundant baseline expression and high inducibility of the Stx glycolipid receptor Gbe in the glomerular microcirculation. Manifestations of the disease arise due to 2 primary pathogenetic mechanisms: (1) direct Stx-mediated injury to vascular endothelial cells that leads to tissue ischemia and dysfunction and (2) a systemic inflammatory response triggered by Stx-mediated release of a wide range of cytokines and chemokines, including IL-6, IL-8, and tumor necrosis factor-alpha.
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Septicemia is rare, except in malnourished children with S dysenteriae infection. Septicemia is sometimes caused by other gram-negative organisms and is related to loss of mucosal integrity by Shigella infection.
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Profound dehydration and hypoglycemia is more common with S dysenteriae infection.
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Shigellasepsis may be complicated with disseminated intravascular coagulation (DIC), bronchopneumonia, and multiple organ failure in lethal cases.
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Arthritis, urethritis, conjunctivitis syndrome is commonly observed in adults carrying human leukocyte antigen (HLA)-B27 histocompatibility antigen.
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Cholestatic hepatitis, if present, is usually mild.
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Myocarditis is identified with cardiogenic shock, arrhythmias, and heart block.
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Rectal prolapse, toxic megacolon, and intestinal obstruction may be present.
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Shigellosis in the first 6 months of life is rare probably due to presence of antibodies to both virulence plasmid-coded antigens and lipopolysaccharides in the breast milk. Shigellosis in the neonatal period results from mother-to-infant fecal-oral transmission during labor and delivery, usually from asymptomatic mothers.
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Symptoms usually begin on the third day of life.
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Septicemia and chronic diarrhea are common.
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Fever may be absent.
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Diarrhea is not usually bloody.
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Intestinal perforation and mortality are more common in this group than in older children.
Shigellosis in patients with HIV infection is often a protracted, chronic, relapsing disease (even when treated with antibiotics). Bacteremia is rare, although it can occur in immunocompromised or malnourished patients. [18]
Physical Examination
Physical examination during acute illness reveals a febrile ill-appearing child. Fever with a temperature as high as 39-40 º C may be noted.
The patient's hydration status should be carefully assessed. Especially note dryness of the oral mucosa, lack of tears, decreased urine output, and loss of skin turgor.
Abdominal examination may reveal generalized mild-to-moderate tenderness with no guarding or rigidity.
In a child who presents with febrile seizures, careful neurologic examination is mandatory to exclude meningitis.
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This illustration depicts a three-dimensional (3D), computer-generated image of a number of rod-shaped, drug-resistant, Shigella sp. bacteria. The artistic recreation was based upon scanning electron microscopic (SEM) imagery. Note that the exterior of the Shigella bacteria is fimbriated, covered by numerous thin, hair-like projections, imparting a furry appearance. Courtesy of the Centers for Disease Control (CDC)/James Archer.
