Figure 1.

The results screen of the prototype of the antibiotic guidance program. The scenario entered in this example is of a urinary tract infection in a woman presenting to the emergency department. The requested output is oral antibiotics only. In this figure, the data boxes are labeled with letters for clarity. The search parameters are repeated back to the user in the top box, labeled A. Next, the ranked list of pathogens from patients matching the query parameters are shown in the box labeled B. Escherichia coli is the most common isolate. Box C displays the projected effectiveness of single antibiotics, based on the tally of the measured and predicted antibiotic susceptibilities of the matching pathogens. These antimicrobials are ranked in descending order of projected effectiveness. Box D shows a similar tally for the 990 two-drug combinations of our formulary antibiotics. Box E displays the list of agents after patient allergies, site of infection, antibiotic restrictions, age-based toxicities, and requested formulation (intravenous versus oral) have been considered. The final recommendation, nitrofurantoin, is presented in box F. This suggestion is calculated by taking the most effective antibiotics on the left and then re-ranking based on drug cost, toxicities, and environmental impact scores. In this system, each drug is assigned a score from one to three in each of these categories. Nitrofurantoin is inexpensive (cost score = 1), relatively safe (toxicity score = 1), and has a low risk or impact on environmental resistance (resistance impact = 1). The final score is calculated by subtracting the predicted effectiveness, 89.7%, from 100%, dividing by 100, and adding the cost, toxicity, and resistance impact scores (((100% − 89.7%)/100) + 1+ 1 + 1 = 3.103 for nitrofurantoin). For the final score, lower is better. In the production version of this system, only the search parameters, the matching pathogens, and the final antimicrobial rankings will be shown to the users.