Determination of the frequency of inadequate antibiotic therapy using calculation of indication failure (IF), cumulative indication failure (CIF), and balanced indication failure (BIF).

Because results of pathogen identification are often lacking when antibiotic therapy is initiated, treatment must frequently be instituted on an empirical basis. The type of empirical therapy will depend on the anticipated pathogen spectrum and naturally also on the prevailing resistance patterns. Inadequate antibiotic therapy may not only be associated with increased overall treatment costs, but will also have adverse effects on mortality. The clinician is frequently faced with an overabundant variety of microbiological data and may fail to interpret them correctly. Therefore, the present study has attempted to "translate" the available microbiological resistance data, frequently presented in the form of percentage rates, into concrete patient numbers and thus illustrate the frequency of inadequate antibiotic therapy. For this purpose, "Indication Failure" (IF), "Cumulative Indication Failure" (CIF) and "Balanced Indication Failure" (BIF) have been calculated based on available microbiological data. For the indication "nosocomial pneumonia", calculations of the BIF show that only one out of 67 or one out of 63 patients is inadequately treated with a therapy with cefepime or imipenem, while one out of 25 patients is inadequately treated when using ceftazidime. However, it must be pointed out that these calculations only represent an interpretation of microbiological data and the success of antibiotic therapy will ultimately also depend on parameters such as the pharmacodynamic properties of an antibiotic or on the immunocompetence of the patient treated.