What is the best course of action for a 12-year-old boy with abdominal pain and retrosternal burning chest pain, with stool test positive for mucus and blood?

Immediate Diagnostic Workup and Empirical Treatment

This 12-year-old boy with abdominal pain, retrosternal burning, and stool positive for mucus and blood requires immediate stool culture for bacterial pathogens (Salmonella, Shigella, Campylobacter, Yersinia, STEC) and empirical treatment with azithromycin 500 mg on day 1, then 250 mg daily for 4 days while awaiting culture results. 1, 2

Clinical Reasoning

The presence of blood and mucus in stool represents an alarm feature that mandates investigation for organic disease, ruling out functional disorders like IBS or abdominal migraine. 3 This clinical picture indicates inflammatory colitis, most likely infectious in a pediatric patient without prior history. 1, 4

Key Diagnostic Steps

Stool testing must be performed immediately for:

• Salmonella, Shigella, Campylobacter, Yersinia, and STEC when diarrhea is accompanied by mucus or blood in stool 1
• The presence of mucus is a key indicator of infectious colitis 4
• Fecal leukocytes and inflammatory markers (calprotectin or lactoferrin) should be obtained if available, as they are highly sensitive for detecting intestinal inflammation 3, 2

Blood cultures should be obtained given the patient's age (<18 years) and signs suggesting systemic infection. 1

Complete blood count and electrolytes are essential to assess for anemia, leukocytosis, and electrolyte disturbances (particularly hypokalemia from diarrheal losses). 3, 2

Why Azithromycin Over Other Options

Azithromycin is the preferred empirical antibiotic for several critical reasons:

• Age-appropriate: Tetracycline (Option B) is contraindicated in children under 8 years due to permanent tooth discoloration and should be avoided in this 12-year-old when safer alternatives exist 2
• Broad coverage: Azithromycin covers the most likely bacterial pathogens including Campylobacter (increasingly quinolone-resistant), Shigella, and Salmonella 2
• Safety profile: Superior to fluoroquinolones in pediatric populations 2
• Dosing: 500 mg on day 1, then 250 mg daily for 4 days is the standard regimen 2

Important Caveats

Do not delay antibiotic therapy while awaiting culture results when a patient presents with bloody/mucoid stools and systemic symptoms. 4, 2 However, if STEC O157:H7 is confirmed, immediately discontinue antibiotics as they can precipitate hemolytic uremic syndrome. 2

Why Not Food Allergy Testing (Option D)

Food allergy testing is inappropriate in this acute presentation because:

• Blood in stool is not a manifestation of food allergy; it indicates mucosal inflammation or infection 3
• While food allergies can cause abdominal pain and mucus, they do not cause bloody stools with positive fecal occult blood 3
• The acute presentation with blood and mucus demands immediate infectious workup, not delayed allergy evaluation 1

Family History Consideration

The mother's chronic abdominal pain raises consideration for inflammatory bowel disease (IBD) if infectious workup is negative. 3 If symptoms persist beyond 14 days despite appropriate antibiotic therapy, evaluate for:

• IBD with colonoscopy and biopsy 3
• Parasitic infections (Giardia, Cryptosporidium) 4
• Postinfectious complications 1

Supportive Management

Initiate oral rehydration immediately with low-osmolarity solutions containing sodium, potassium, chloride, bicarbonate, and glucose without waiting for culture results. 4, 2

Monitor closely for:

• Frequency of bowel movements and stool characteristics 2
• Hydration status (skin turgor, mucous membranes, vital signs) 2
• Signs of hemodynamic instability or sepsis requiring hospitalization 1