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Shigellosis: Treatment & Medication
Updated: Aug 22, 2008
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Treatment
Medical Care
- General supportive care of patients with shigellosis includes the following:
- High fever in children should be treated.
- Narcotic-related antidiarrheals should be avoided.
- Antibiotic treatment is indicated in most patients.
- Antimotility agents should be avoided. They have the potential to worsen symptoms and may predispose to toxic dilation of the colon.
- For fluid and electrolyte supplementation, oral rehydration solutions are preferable.
Consultations
Consult a gastroenterologist or an infectious diseases expert if the Shigella infection is prolonged or if the patient experiences a severe course of shigellosis that is unresponsive to antibiotics.
Diet
Clear liquids followed by a low residue, lactose-free diet are recommended until symptoms of shigellosis resolve.
Medication
Shigella infection produces a self-limited diarrheal illness that lasts 5-7 days and may not require antibiotics in individuals who are otherwise healthy. Antibiotic treatment is recommended for infirm or older patients, malnourished children, patients infected with HIV, food handlers, health care workers, and children in day care centers.
For public health reasons, most experts recommend treating any person whose stool culture is positive for Shigella species. Moreover, antibiotics have been shown to decrease the duration of fever and diarrhea by about 2 days. The shorter duration of shedding with antibiotic therapy can reduce the risk of person-to-person spread.
Ampicillin was widely used in the past but is no longer an effective empiric treatment in the United States because of antibiotic resistance. In fact, antibiotic resistance to Shigella species is widespread and increasing worldwide. Thus, antibiotic susceptibility testing is essential for the management of patients with suspected Shigella infection.
Given the widespread resistance to ciprofloxacin as well as trimethoprim-sulfamethoxazole and azithromycin, a third-generation cephalosporin is appropriate empiric therapy in the setting of acute illness. The treatment of choice for HIV-infected patients is a quinolone for 5 days.
Antibiotics
Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.
Ceftriaxone (Rocephin)
Third-generation cephalosporin with broad-spectrum, gram-negative activity; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms. Bactericidal activity results from inhibiting cell wall synthesis by binding to one or more penicillin binding proteins. Exerts antimicrobial effect by interfering with synthesis of peptidoglycan, a major structural component of bacterial cell wall. Bacteria eventually lyse due to the ongoing activity of cell wall autolytic enzymes while cell wall assembly is arrested.
Highly stable in presence of beta-lactamases, both penicillinase and cephalosporinase, of gram-negative and gram-positive bacteria. Approximately 33-67% of dose excreted unchanged in urine, and remainder secreted in bile and ultimately in feces as microbiologically inactive compounds. Reversibly binds to human plasma proteins, and binding have been reported to decrease from 95% bound at plasma concentrations <25 mcg/mL to 85% bound at 300 mcg/mL.
Adult
Uncomplicated infections: 250 mg IM once; not to exceed 4 g
Severe infections: 1-2 g IV qd, or divided bid; not to exceed 4 g/d
Pediatric
Infants and children: 50 mg/kg/d IV/IM qd; not to exceed 1.5 g/d for 5 d
Probenecid may increase ceftriaxone levels; coadministration with ethacrynic acid, furosemide, and aminoglycosides may increase nephrotoxicity
Documented hypersensitivity; hyperbilirubinemic neonates, particularly those who are premature
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Adjust dose in severe renal insufficiency (high doses may cause CNS toxicity); superinfections, and promotion of non-susceptible organisms may occur with prolonged use or repeated therapy; caution in breast-feeding women; may displace bilirubin from albumin binding sites increasing the risk of kernicterus; caution with gallbladder, biliary tract, liver or pancreatic disease; or in patients with history of colitis or penicillin hypersensitivity
Ciprofloxacin (Cipro)
Fluoroquinolone that inhibits bacterial DNA synthesis and, consequently, growth.
Adult
500 mg PO bid for 5 d
Pediatric
Not recommended
Antacids, iron salts, and zinc salts may reduce serum levels; administer antacids 2-4 h before or after taking fluoroquinolones; cimetidine may interfere with metabolism of fluoroquinolones; ciprofloxacin reduces therapeutic effects of phenytoin; probenecid may increase ciprofloxacin serum concentrations; may increase toxicity of theophylline, caffeine, cyclosporine, and digoxin (monitor digoxin levels); may increase effects of anticoagulants (monitor PT)
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
In prolonged therapy, perform periodic evaluations of organ system functions (eg, renal, hepatic, hematopoietic); adjust dose in renal function impairment; superinfections may occur with prolonged or repeated antibiotic therapy
Trimethoprim-sulfamethoxazole (Bactrim, Septra, Bactrim DS, Cotrim)
Inhibits bacterial growth by inhibiting synthesis of dihydrofolic acid. Reasonable DOC in the United States due to few resistant strains.
Dosing may be based on TMP component.
Adult
SMX 800 mg/160 mg TMP PO bid for 5 d
Pediatric
<2 months: Do not administer
>2 months: SMX 25 mg/kg PO bid for 5 d and 5 mg TMP/kg PO bid
May increase PT when used with warfarin (perform coagulation tests and adjust dose accordingly); coadministration with dapsone may increase blood levels of both drugs; coadministration of diuretics increases incidence of thrombocytopenic purpura in the older population; phenytoin levels may increase with coadministration; may potentiate effects of methotrexate in bone marrow depression; hypoglycemic response to sulfonylureas may increase with coadministration; may increase levels of zidovudine; coadministration with MAOIs may increase toxicity of both agents
Documented hypersensitivity; megaloblastic anemia due to folate deficiency
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Discontinue at first appearance of skin rash or sign of adverse reaction; obtain CBCs frequently; discontinue therapy if significant hematologic changes occur; goiter, diuresis, and hypoglycemia may occur with sulfonamides; prolonged IV infusions or high doses may cause bone marrow depression (if signs occur, administer 5-15 mg/d leucovorin); caution in folate deficiency (eg, chronic alcoholism, older population, patients receiving anticonvulsant therapy, patients with malabsorption syndrome); hemolysis may occur in G-6-PD deficient individuals; patients with AIDS may not tolerate or respond to TMP-SMZ; caution in renal or hepatic impairment (perform urinalyses and renal function tests during therapy); administer fluids to prevent crystalluria and stone formation
Azithromycin (Zithromax)
Acts by binding to 50S ribosomal subunit of susceptible microorganisms and blocks dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. Nucleic acid synthesis is not affected.
Concentrates in phagocytes and fibroblasts as demonstrated by in vitro incubation techniques. In vivo studies suggest that concentration in phagocytes may contribute to drug distribution to inflamed tissues.
Treats mild-to-moderate microbial infections.
Plasma concentrations are very low, but tissue concentrations are much higher, giving it value in treating intracellular organisms. Has a long tissue half-life.
Adult
Day 1: 500 mg PO
Days 2-5: 250 mg PO qd
Pediatric
<6 months: Not established
>6 months:
Day 1: 12 mg/kg PO once; not to exceed 500 mg/d
Days 2-5: 6 mg/kg PO qd; not to exceed 250 mg/d
May increase toxicity of theophylline, warfarin, and digoxin; effects are reduced with coadministration of aluminum and/or magnesium antacids; nephrotoxicity and neurotoxicity may occur when coadministered with cyclosporine
Documented hypersensitivity; hepatic impairment; do not administer with pimozide
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Site reactions can occur with IV route; bacterial or fungal overgrowth may result from prolonged antibiotic use; may increase hepatic enzymes and cholestatic jaundice; caution in patients with impaired hepatic function or prolonged QT intervals
More on Shigellosis |
| Overview: Shigellosis |
| Differential Diagnoses & Workup: Shigellosis |
 Treatment & Medication: Shigellosis |
| Follow-up: Shigellosis |
| References |
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References
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Policar M. Shigellosis. In: Ferri's Clinical Advisor: Instant Diagnosis and Treatment. 2005:752-754.
Sivapalasingam S, Nelson JM, Joyce K, et al. High prevalence of antimicrobial resistance among Shigella isolates in the United States tested by the National Antimicrobial Resistance Monitoring System from 1999 to 2002. Antimicrob Agents Chemother. Jan 2006;50(1):49-54. [Medline].
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Wolf DC, Gianella RA. Invasive pathogens. Consultations in Gastroenterology. 1996;381-384.
Further Reading
Keywords
shigellosis, dysentery, bacillary dysentery, diarrhea, bacterial infection, intestinal infection, Shigella organisms, Shigella boydii, Shigella dysenteriae, Shigella sonnei, Shigella flexneri, S dysenteriae, S flexneri, S sonnei, S boydii
