For a study, it was determined that antibiotics were an effective treatment for bacterial pathogen-caused illnesses. On the other hand, antibiotics were often broad-spectrum and can kill beneficial microorganisms in body habitats such as the gut, thus impacting the commensal gut microbiota. Furthermore, the evolvement and development of bacteria for eloping antibiotic resistance has complicated the therapy and posed considerable therapeutic problems. As a result, there was a pressing medical need to find new antibiotic treatments that will target specific problem-causing bacteria while leaving the gut microbiota alone, which was often helpful. The use of lytic bacteriophages for controlling bacterial infections, especially those caused by multidrug-resistant organisms, was one such prospective alternate method. The researchers used an in vitro model of the small intestine to compare the efficacy of a bacteriophage cocktail targeting Escherichia coli with that of a broad-spectrum antibiotic (ciprofloxacin). The parameters studied were (i) the effect on a pre-selected targeted E. coli strain and (ii) the effect on a non-targeted bacterial population chosen to represent a defined microbial consortium found in a healthy small intestine. Throughout these investigations, the researchers also tested the stability of bacteriophages against various pH and bile concentrations usually observed in the human digestive tract. Comparable to the simulated ileum, the bacteriophage cocktail was marginally more stable in the simulated duodenum (0.12 vs 0.58 log decrease in phage titers, respectively). It was just as effective as ciprofloxacin at reducing E. coli in unreal gut circumstances (2–3 log reduction) but had significantly less impact (none) on commensal, non-targeted bacteria.