Empiric therapy or empirical therapy is therapy based on experience and, more specifically, therapy begun on the basis of a clinical educated guess in the absence of complete or perfect information. Thus it is applied before the confirmation of a definitive diagnosis or in the absence of complete understanding of mechanism, whether the biological mechanism of pathogenesis or the therapeutic mechanism of action. The name shares the same stem with empirical evidence, involving an idea of practical experience. Empiric therapy is most often used when antibiotics are given to a person before the specific bacterium causing an infection is known. Fighting an infection sooner rather than later is important to minimize morbidity, risk, and complications, so there is value in getting started with good information rather than waiting around for better information. Examples of this include antibiotics given for pneumonia, urinary tract infections, and suspected bacterial meningitis in newborns aged 0 to 6 months. Empiric antibiotic therapy thus may be thought of as taking the initiative against an anticipated and likely cause of infectious disease.
Empiric antibiotic therapy
Empiric antibiotics are typically broad-spectrum, in that they treat both Gram-positive and Gram-negative bacteria. When more information is known (as from a blood culture), treatment may be changed to a narrow-spectrum antibiotic which more specifically targets the bacterium known to be causing disease.
The advantage of indicating antibiotics empirically exists where a causative pathogen is likely albeit unknown and where diagnostic tests will not be influential to treatment. In this case, there may be little if any perceived benefit of using what may be costly and inconclusive tests that will only delay treatment of the same antibiotics. The empirical use of broad-spectrum antibiotics increases, by selection, the prevalence of bacteria resistant to several antibiotics. However, the delay and expense that would be required to perform definitive species identification in every single clinical case are not affordable, so some degree of trade-off is accepted on the principle of the benefits outweighing the risk.