Max 500 mg/day · Duration: 5 days · Only when antibiotic therapy is indicated — day 1: 10 mg/kg (max 500 mg); days 2–5: 5 mg/kg/day (max 250 mg/day) per AAP macrolide guidance for Yersinia · uncomplicated viral mesenteric adenitis does not require antibiotics
• Antibiotics are not recommended for uncomplicated viral mesenteric adenitis after surgical emergencies are excluded (StatPearls, NICE, Mayo Clinic).
• Treat when confirmed or strongly suspected Yersinia enterocolitica (stool culture/PCR, bloody diarrhea, terminal ileitis on imaging) with severe or prolonged symptoms.
• Treat when bacteremia, immunocompromise, hemodynamic instability, or failure of supportive care after 48–72 h with bacterial cause suspected (CDC Yersinia, AAP).
• Do not use penicillins or first-generation cephalosporins for Yersinia — intrinsically resistant (CDC).
• If acute appendicitis cannot be excluded, manage as appendicitis with pediatric surgery — do not label as mesenteric adenitis without imaging/surgical assessment (NICE NG122 principles, WSES).
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Ceftriaxone • i.v. • 50–75 mg/kg/day • 1×/day
Max 2000 mg/day · Duration: 5–7 days · Severe disease, hospitalization, or Yersinia bacteremia — third-generation cephalosporins effective for invasive Yersinia (CDC, AAP)
• Ceftriaxone: hospitalized child unable to take oral antibiotics, severe systemic illness, or documented Yersinia bacteremia (CDC — third-generation cephalosporins for invasive disease).
• Trimethoprim/sulfamethoxazole: susceptible Yersinia when azithromycin unavailable, intolerant, or resistance concern — confirm susceptibility when possible.
• Supportive care only: afebrile or low-grade fever, tolerating oral intake, imaging consistent with viral mesenteric adenitis and normal appendix — hydration, analgesia (ibuprofen/acetaminophen), observation (StatPearls, NICE).
• Mycobacterial or atypical infection: prolonged fever, weight loss, exposure — obtain purified protein derivative/IGRA and specialist referral; not covered by empiric regimens above.
• Surgical consultation before antibiotics when appendicitis, intussusception, or ovarian/testicular pathology cannot be excluded — RLQ pain with high PAS, peritoneal signs, or toxic appearance (NICE, WSES, pediatric surgery pathways).
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Clinical notes
• Diagnostic criteria: acute abdominal pain (often RLQ or periumbilical) with fever ± vomiting/diarrhea, often after URI or gastroenteritis; ultrasound showing enlarged mesenteric lymph nodes (commonly >5 mm short axis) with non-compressible normal appendix and no surgical emergency (StatPearls, pediatric imaging literature).
• Differentiate from acute appendicitis: mesenteric adenitis more common in children <10 years, often less focal RLQ tenderness, follows viral prodrome; appendicitis shows non-compressible appendix >6 mm, appendicolith, higher PAS/Alvarado — when uncertain, repeat exam, imaging, or surgical consult (NICE NG122, WSES).
• Uncomplicated viral mesenteric adenitis is self-limiting — antibiotics do not shorten illness and are not recommended (StatPearls, Mayo Clinic, NICE supportive-care principles); bacterial antibiotics only for documented/severe Yersinia or other invasive bacterial disease (CDC, ESPGHAN enteric principles).
• Observation and supportive treatment: oral hydration, analgesia, antiemetics if needed, short-stay unit or outpatient management when diagnosis secure, pain improving, and oral intake tolerated — most recover within 1–4 weeks (Mayo Clinic, StatPearls).
• Hospital admission if unable to hydrate orally, severe pain requiring IV analgesia, diagnostic uncertainty (cannot exclude appendicitis), toxic appearance, or worsening at 24–48 h; follow-up in 24–48 h if discharged — return immediately for worsening pain, persistent fever >48 h, bilious vomiting, or peritoneal signs (NICE, pediatric emergency pathways).
• StatPearls — Mesenteric adenitis evaluation and management (2024)
