Acute Infectious Gastroenteritis Supportive Care and Targeted Antibiotic Therapy
Acute infectious diarrhea is managed first with assessment for dehydration and rehydration therapy using oral rehydration solution (ORS). Antibiotic therapy is reserved for suspected or confirmed invasive bacterial etiologies or specific bacterial syndromes, with avoidance of antibiotics in Shiga toxin–producing E. coli (STEC) due to risk of harm. [1]
Supportive Care and Rehydration Therapy
Reduced-osmolarity ORS is recommended as first-line therapy for acute diarrheal illness. [1] Isotonic intravenous fluids such as lactated Ringer’s solution or normal saline should be administered when there is severe dehydration, shock, altered mental status, or failure of ORS therapy. [1] An antinausea and antiemetic (eg, ondansetron) can be given to facilitate tolerance of oral rehydration in children >4 years of age and in adolescents with acute gastroenteritis associated with vomiting. [1]
Ancillary Symptom-Directed Therapy
Antimotility and antisecretory agents can be used to shorten duration of diarrhea in adults. [1] Loperamide has demonstrated reduction in diarrhea prevalence at 24 and 48 hours and reduction in total duration of diarrhea in studies that excluded moderate to severe dehydration. [1] Routine antiemetic therapy for acute gastroenteritis is not supported in children <4 years of age or in adults. [1]
Indications for Stool Testing to Guide Bacterial Treatment
Stool testing should be performed for Salmonella, Shigella, Campylobacter, C. difficile, and STEC in patients with diarrhea accompanied by fever, bloody or mucoid stools, severe abdominal cramping or tenderness, or signs of sepsis. [1] STEC O157 should be assessed by culture with Shiga toxin testing or Shiga toxin gene detection, with non-O157 STEC detected by Shiga toxin or genomic assays. [1] Blood cultures should be obtained from infants <3 months of age, people with septicemia, and when enteric fever is suspected. [1]
Empiric Antibiotic Use Decisions
Empiric antimicrobial therapy for bloody diarrhea is not recommended in immunocompetent children and adults while awaiting investigation results except for specific exceptions. [1] Exceptions for empiric therapy in immunocompetent patients with bloody diarrhea include infants <3 months of age with suspicion of bacterial etiology and ill immunocompetent people with documented fever in a medical setting plus abdominal pain and bacillary dysentery presumptively due to Shigella. [1] Empiric antimicrobial therapy should be considered in immunocompromised people with severe illness and bloody diarrhea. [1] In most people with acute watery diarrhea without recent international travel, empiric antimicrobial therapy is not recommended. [1] Empiric treatment should be avoided in persistent watery diarrhea lasting 14 days or more. [1] In trials of empiric treatment for acute watery diarrhea, the benefit was reported as about 1 day shorter illness on average, which was insufficient to recommend routine empiric therapy in most patients. [1]
Antibiotic Selection Algorithm by Common Bacterial Pathogen
Recommended antimicrobial agents for commonly identified bacterial causes are summarized below. [1]
- Campylobacter (first choice): Azithromycin. [1]
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Campylobacter (alternative): Ciprofloxacin. [1]
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Salmonella enterica serovar Typhi or Paratyphi: Ceftriaxone or ciprofloxacin. [1]
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Salmonella enterica serovar Typhi or Paratyphi (alternatives): Ampicillin, TMP-SMX, or azithromycin. [1]
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Shigella (empiric or targeted treatment when indicated): Azithromycin or ciprofloxacin or ceftriaxone. [1]
- Shigella (alternatives): TMP-SMX or ampicillin if susceptible. [1]
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Fluoroquinolone avoidance: Clinicians treating shigellosis for whom antibiotic treatment is indicated should avoid prescribing fluoroquinolones if the ciprofloxacin MIC is 0.12 μg/mL or higher even when the isolate is reported as susceptible. [1]
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Vibrio cholerae (noninvasive disease when treatment is indicated): Doxycycline. [1]
- Vibrio cholerae (alternative options): Ciprofloxacin, azithromycin, or ceftriaxone. [1]
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Vibrio cholerae (invasive disease): Ceftriaxone plus doxycycline. [1]
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Non–Vibrio cholerae bacterial causes: Antimicrobial therapy is usually not indicated for noninvasive disease. [1]
- Yersinia enterocolitica: TMP-SMX (first choice). [1]
- Yersinia enterocolitica (alternatives): Cefotaxime or ciprofloxacin. [1]
Monotherapy Versus Combination Therapy
Single-agent therapy is recommended for noninvasive Vibrio cholerae disease when treatment is given. [1] Combination therapy is recommended for invasive Vibrio cholerae disease as ceftriaxone plus doxycycline. [1] Some invasive nontyphoidal bacterial syndromes listed in the guideline require combination therapy, including invasive disease treated with TMP-SMX plus an aminoglycoside as specified in the antimicrobial table. [1]
Key Contraindications and High-Risk Pathogen Nuances
Antibiotic avoidance is recommended for STEC infections because no clear benefit exists for treating less virulent STEC with antibiotics and there is potential harm, especially for STEC that produce Shiga toxin 2. [1] STEC identification is important to reduce complications and reduce person-to-person transmission risk, including use of appropriate testing for Shiga toxin and O157 versus non-O157 STEC. [1]
Treatment Targets and Goals of Therapy
Rehydration targets include restoration of intravascular volume and correction of dehydration, with escalation to isotonic intravenous fluids when ORS is not tolerated or ineffective. [1] Antibiotic therapy targets the identified bacterial pathogen when stool or clinical features strongly support bacterial invasive disease, with avoidance of antibiotics in STEC to prevent adverse outcomes. [1]
Common Pitfalls to Avoid
Avoid routine empiric antibiotics for acute watery diarrhea in most patients without features suggesting invasive bacterial infection. [1] Avoid empiric antibiotic therapy for bloody diarrhea in immunocompetent patients unless guideline exceptions are present. [1] Avoid fluoroquinolones in indicated Shigella treatment when ciprofloxacin MIC is 0.12 μg/mL or higher despite susceptibility reporting. [1] Avoid antibiotic treatment in STEC syndromes when Shiga toxin–producing E. coli is suspected or confirmed. [1] End with the avoidance of antibiotic overuse as a central safety strategy across acute infectious diarrhea syndromes. [1]