Every year, tens of thousands of people die of infections from antibiotic-resistant bacteria. Phage therapy has been suggested as an alternative because bacteria resistant to antibiotics may still be susceptible to phages. Furthermore, phages have the advantage of being more specific and thus less likely to harm beneficial bacteria. However, phages may have limited effectiveness in combating bacteria since bacteria possess several antiviral defense mechanisms and can quickly develop resistance to phages. The purpose of this study was to compare the effectiveness and specificity of antibiotics and phages in combating bacteria. To this end, we exposed strains of the bacteria Escherichia coli to T4 bacteriophages and antibiotics and assessed effectiveness and specificity of bacterial killing. Fission yeast, a unicellular eukaryotic organism, was used as a control. Cell growth, phage plaque formation, or cell concentrations were observed or measured. It was found that T4 phages are more specific and effective in fighting or inhibiting both antibiotic-resistant and sensitive bacteria than antibiotics. One phage can kill at least 4000 actively growing bacterial cells within two hours. Therefore, the data suggest that phage therapy can be developed as an efficient tool to combat antibiotic-resistant bacteria.