Coliphages given orally to children with bacterial diarrhea appeared in the stool, but did not improve clinical outcome.
In microbiologically diagnosed E. coli diarrhea, pathogen titers were close to the replication threshold of coliphages.
Acute bacterial diarrhea displayed a marked dysbiosis with fecal streptococci that stabilized with recovery from diarrhea.
Antibiotic resistance of bacterial infections reached alarming levels. Phage therapy is a potential alternative antimicrobial. We demonstrated that two different oral phage preparations did not improve acute bacterial diarrhea in children from Bangladesh. We observed fecal excretion of the oral phage, but no major phage amplification in the gut. E. coli pathogen levels were low and the fecal microbiota showed a transient overgrowth with streptococci. Future phage trials should first verify the titer and association of the targeted pathogen with the disease.