What is the appropriate management for a 30-year-old female presenting with fever, diarrhea, and vomiting for 24 hours?

Differential Diagnosis: Acute Gastroenteritis

This 30-year-old female most likely has acute infectious gastroenteritis, with viral etiology (particularly norovirus or rotavirus) being the most common cause, though bacterial pathogens (Salmonella, Campylobacter, E. coli) and less commonly parasitic infections should be considered based on exposure history and clinical features. 1, 2

Primary Diagnostic Considerations

Acute Infectious Gastroenteritis (Most Likely)

• Viral gastroenteritis is the predominant cause of acute diarrhea with fever and vomiting in immunocompetent adults, accounting for the majority of cases 3, 2
• Common viral pathogens include norovirus, rotavirus, and adenovirus 2
• Bacterial gastroenteritis should be considered if symptoms include bloody diarrhea, high fever (>38.5°C), or severe abdominal cramping 1
  • Common bacterial causes: Salmonella, Campylobacter jejuni, Shigella, enterotoxigenic E. coli, and Vibrio cholerae 2
• Parasitic infections (Giardia, Entamoeba histolytica) are less common but should be considered with prolonged symptoms or specific travel history 2

Clinical Features Distinguishing Etiologies

• Watery diarrhea with vomiting and fever without blood suggests viral or enterotoxigenic bacterial etiology 1, 3
• Bloody diarrhea (dysentery) suggests invasive bacterial pathogens like Shigella, Campylobacter, or enterohemorrhagic E. coli 1
• Severe abdominal cramping may be an early warning sign of more severe gastrointestinal syndrome 1
• Duration of 24 hours is consistent with acute infectious gastroenteritis rather than chronic causes 1

Secondary Differential Considerations

Food Poisoning

• Preformed toxin-mediated illness (Staphylococcus aureus, Bacillus cereus) typically presents with rapid onset (1-6 hours) of vomiting and may have shorter duration 4
• History of recent food consumption, particularly high-risk foods (dairy, eggs, undercooked meat), supports this diagnosis 4

Other Considerations to Exclude

• Medication-induced diarrhea: Recent antibiotic use raises concern for Clostridioides difficile infection 3
• Appendicitis or other surgical abdomen: Severe, localized abdominal pain with peritoneal signs would suggest surgical pathology 2
• Inflammatory bowel disease flare: Less likely with acute 24-hour presentation without prior history 1
• Pregnancy-related conditions: Morning sickness or hyperemesis gravidarum should be considered in reproductive-age females 3

Key Historical and Examination Features to Determine Etiology

Critical History Elements

• Exposure history: Recent travel, contaminated water exposure, contact with ill individuals, daycare exposure 1, 3
• Food history: Recent meals, particularly high-risk foods consumed in past 72 hours 4
• Medication history: Recent antibiotic use (raises concern for C. difficile), immunosuppressive medications 1, 3
• Stool characteristics: Presence of blood, mucus, or purely watery consistency 1
• Associated symptoms: Severe abdominal cramping, tenesmus, or neurological symptoms 1

Physical Examination Priorities

• Hydration status assessment: Skin turgor, mucous membrane moisture, capillary refill time, mental status, orthostatic vital signs 3, 4
• Severity categorization: Mild (3-5% deficit), moderate (6-9%), or severe (≥10%) dehydration 3, 4
• Abdominal examination: Assess for peritoneal signs, severe localized tenderness, or distention that would suggest surgical pathology 2
• Vital signs: Fever pattern, tachycardia, and hypotension indicating severity 3, 4

Diagnostic Testing Considerations

When Testing is NOT Routinely Indicated

• Antimicrobial agents have limited usefulness since viral agents are the predominant cause in acute gastroenteritis 3
• Stool cultures and diagnostic testing are not routinely needed for immunocompetent adults with acute watery diarrhea lasting <24 hours 1

When Testing IS Indicated

• Bloody diarrhea or dysentery warrants stool culture and consideration of Shigella, Campylobacter, or enterohemorrhagic E. coli 1
• Recent antibiotic use requires C. difficile testing 3
• Recent foreign travel to endemic areas may warrant stool ova and parasite examination 3
• Immunocompromised status requires more aggressive diagnostic evaluation 1
• Symptoms persisting >5 days warrant stool studies 1
• Severe dehydration or toxic appearance may require electrolyte panel and complete blood count 4, 5

Common Pitfalls to Avoid

• Do not delay rehydration while awaiting diagnostic test results; initiate oral rehydration solution immediately 3, 4
• Do not prescribe empiric antibiotics for acute watery diarrhea without specific indications (bloody diarrhea, high fever, immunocompromise, or prolonged symptoms >5 days) 1, 3
• Do not use antimotility agents (loperamide) if bloody diarrhea, high fever, or suspected inflammatory/invasive diarrhea is present, as this may precipitate toxic megacolon 1, 6
• Do not overlook pregnancy testing in reproductive-age females, as this may alter management 3
• Do not assume viral etiology if patient appears toxic, has severe abdominal pain with peritoneal signs, or has bloody diarrhea 1, 2