Bacterial Pathogens Causing Microscopic Hematochezia

Diagnostic Approach

The American College of Physicians recommends stool testing for Salmonella, Shigella, Campylobacter, Yersinia, C. difficile, and STEC in patients presenting with diarrhea accompanied by fever, bloody or mucoid stools, severe abdominal cramping or tenderness, or signs of sepsis 1
The Infectious Diseases Society of America suggests that all stools from patients with acute community-acquired diarrhea should be cultured for E. coli O157:H7 on selective and differential agar and simultaneously tested for non-O157 STEC using assays that detect Shiga toxin or the genes encoding these toxins 3
Standard bacterial culture should include testing for Salmonella, Shigella, and Campylobacter species, with a diagnostic yield ranging from 0.6% for Shigella to 1.4% for Campylobacter 1, 2

Campylobacter jejuni is the most commonly isolated bacterial pathogen in many studies, with fever present in 47-91% of cases, blood typically appearing 2-4 days after initial watery diarrhea, and severe abdominal pain or cramping in >90% of older children 2, 4
Shigella species present with classic dysentery syndrome, are more likely to produce Shiga toxin, and can cause hemolytic uremic syndrome (HUS) 1
STEC infections often present with bloody diarrhea but minimal or no fever, and it is critical to identify them due to the risk of HUS 1, 2, 3

The Centers for Disease Control and Prevention recommend that antibiotics should not be given when STEC infection is suspected or confirmed, as they may increase the risk of HUS, and instead suggest early parenteral volume expansion to reduce the risk of renal damage 1, 3

The Infectious Diseases Society of America suggests that blood cultures should be obtained from immunocompromised patients, those with signs of septicemia, and infants <3 months of age 1
Infants under 6 months are at higher risk for severe disease and complications, warranting prompt treatment with azithromycin 6

The American Academy of Pediatrics recommends monitoring for postinfectious complications including reactive arthritis, Guillain-Barré syndrome, and HUS 1