From the Guidelines
Culturing bloody stool in pediatric patients is crucial to identify specific bacterial pathogens, guide treatment decisions, and prevent complications, as recommended by the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1.
Importance of Stool Culture
When a child presents with bloody stool, obtaining a stool culture can determine if organisms such as Salmonella, Shigella, Campylobacter, or E. coli O157:H7 are present, which require different management approaches. For example, antibiotics like azithromycin (10 mg/kg/day for 3 days) may be appropriate for Shigella, while they should be avoided in suspected E. coli O157:H7 as they might increase the risk of hemolytic uremic syndrome 1.
Public Health Implications
Stool cultures also help distinguish infectious causes from non-infectious conditions like inflammatory bowel disease, allergic colitis, or intussusception, which require entirely different treatments. Additionally, identifying specific pathogens has public health implications, as certain infections require notification of health authorities and contact tracing to prevent outbreaks 1.
Treatment Decisions
The culture results directly impact treatment decisions, including whether to use antibiotics, which specific antibiotic to choose based on susceptibility testing, and how to manage the patient's hydration and supportive care. Early identification of particularly virulent STEC infection (eg, STEC O157 and other Shiga toxin 2–producing strains) facilitates rapid implementation of measures in the home that prevent cross-contamination 1.
Key Considerations
- The 2017 IDSA guidelines recommend empiric antimicrobial therapy for bloody diarrhea in certain situations, such as infants <3 months of age with suspicion of a bacterial etiology, or ill immunocompetent people with fever, abdominal pain, and bacillary dysentery presumptively due to Shigella 1.
- Antimicrobial therapy for people with infections attributed to STEC O157 and other STEC that produce Shiga toxin 2 should be avoided, as it may increase the risk of hemolytic uremic syndrome 1.
- Regular and consistent follow-up of patients recovering from diarrhea-associated HUS is recommended until laboratory and clinical parameters have returned to normal values 1.
From the Research
Importance of Culturing Bloody Stool in Pediatric Patients
- Culturing bloody stool in pediatric patients is crucial for identifying the underlying cause of the infection, which can be bacterial, viral, or parasitic 2, 3, 4.
- The most common bacterial causes of bloody diarrhea in children include Salmonella, Shigella, and Shiga toxin-producing Escherichia coli (STEC) 5, 2, 6.
- Culturing the stool can help determine the susceptibility of the bacteria to various antibiotics, including azithromycin, which is an alternative treatment option for bacterial diarrhea 5, 6.
- In pediatric patients, it is essential to identify the cause of bloody diarrhea to provide appropriate treatment and prevent complications, such as hemolytic uremic syndrome (HUS) 3.
Benefits of Stool Culture in Pediatric Patients
- Stool culture can help identify the specific bacterial cause of the infection, allowing for targeted antibiotic therapy 2, 6.
- Culturing the stool can also help detect antibiotic resistance, which is becoming increasingly common in bacterial pathogens 5, 6.
- In neonates, bloody stools can be caused by various conditions, including cow's milk protein allergy, swallowed blood syndrome, and necrotizing enterocolitis (NEC) 4.
- Stool culture can help differentiate between these conditions and guide appropriate management.
Laboratory Tests for Diagnosing Bloody Diarrhea
- Various laboratory tests, including stool PCR, culture, and enzyme immunoassay (EIA), can be used to diagnose bloody diarrhea in pediatric patients 2, 3.
- The choice of test depends on the suspected cause of the infection and the availability of resources.
- Stool culture remains the gold standard for diagnosing bacterial causes of bloody diarrhea, but molecular tests like PCR are becoming increasingly popular due to their rapid turnaround time and high sensitivity 2, 3.