Evaluation of Fecal Occult Blood Testing Kits for Rapid Point-of-Care Diagnosis of Invasive Diarrhea in Young Children

Abstract BackgroundAntimicrobials are only indicated in acute childhood diarrhea when the infection is invasive (and therefore often bloody), or persistent. Rapid and cost-effective screening for invasive diarrhea at the point of care can therefore inform treatment decisions. Multiple rapid fecal occult blood testing (FOBT) kit brands are widely available in Nigeria. This study aimed to compare the diagnostic utility of locally procurable FOBT kits in invasive infantile diarrhea to the innovators product, using fecal microscopy as the gold standard. Materials and MethodsFecal specimens from 46 children under 5 years old with diarrhea, being collected as part of ongoing case-control studies, were tested according to manufacturers’ instructions for each of five FOBT kits. Fecal microscopy for occult blood, and culture for bacterial pathogens were also performed concomitantly using standard procedures. ResultsStool microscopy confirmed almost ubiquitous presence of white blood cells in stool from children with diarrhea, whereas red blood cells were less commonly detected. A positive FOBT reaction was only seen when red blood cells were present at more than trace levels and was partially correlated with the presence of a potentially invasive pathogen. Each of the five FOBT kits tested showed 54-61% sensitivity, 87-90% specificity, and acceptable positive- and negative-predictive values for invasive diarrhea. ConclusionsFour inexpensive, locally available kits identified invasive pediatric diarrheas showed reasonable performance for detecting likely invasive diarrhea and performed similarly to the more difficult-to-procure innovator’s product. FOBT kits are a rapid option for presumptive diagnosis of invasive diarrhea, are a viable alternative to stool microscopy for paediatric specimens at the point-of-care, and could serve as early warning indicators for dysentery outbreaks.