At present, ABC Calc only deals with “Antibacterials for systemic use“ also known as group J01 of the ATC classification system, as well as antibacterials in the following ATC groups: A02BD (Combinations for eradication of Helicobacter pylori), A07AA (Intestinal antiinfectives, incl. for selective decontamination of the digestive tract), J04A (Drugs fro treatment of tuberculosis) and P01A (Agents against amoebiasis and other protozoal diseases). Antibacterials for topical use, which are found in other ATC groups, are excluded. Additionally, ABC Calc cannot deal with several antibiotic combinations, mainly because DDDs have not been defined for these combinations. Before a solution is found to this problem, we nevertheless encourage users to record information on special antibiotic combinations to help identify the ones that are used in hospitals.