1. Solvent/diluent for antibiotics: the CLSI (Clinical & Laboratory Standards Institute) standard have a list of antibiotics with a list of solvent and diluent. You can use the recommended solvent given by the CLSI, however, for the diluent you can use water.
2. Note that some solvents can kill bacteria thus leading to conflicting results, so keep those solvents <1%. Examples include: DMSO, ethanol, etc. Research carefully what type of solvent/diluent you are using and keep them as diluted as possible
3. Since the plate has 10-fold phages and 2-fold antibiotics, you will need 2 dilution plates (one for each treatment) and then pipette the diluted antibiotic/phage into the final Master plate. So in total you will need three plates.
4. The OD ~ 1x109 CFU/mL only works for E. coli here. If the organism has different growth curve, new OD for 1x109 CFU/mL needs to be determined.
5. There is inoculum effect in terms of antibiotic treatment, thus one consistent inoculum is required across various synograms for comparison purposes. High inoculum was purposefully chosen in our study to detect phage-antibiotic interactions that happen at the sublethal interface.
6. NOTE that synogram works best for species that do not form heavy biofilms such as Bacillus that would mess with the OD readings