ABSTRACT
The right choice of antibiotic is one of the the most important factors, though not the only one, in determining the success or failure of an antimicrobial therapy. The drug chosen should combine the highest in vivo efficacy, Le., the best chance of success, with the least likelihood of side effects. The principal objective in giving an antibiotic is to achieve a concentration at the site of infection that is sufficient to kill or inhibit the growth of the bacteria present. At the same time, the antibiotic(s) and the dosage regimen chosen have to be as safe as possible for the patient with regard to the possible occurrence of adverse effects. Thus, to achieve clinical efficacy associated with safety, the prescriber has to deal with several important variables, depending on the patient (age, severity of illness, renal and/or hepatic function, immune status, hypersensitivity to antibiotics), on the infection (site and severity), on the causative organism (level of sensitivity or resistance) and on the antibiotic (pharmacokinetics, pharmacodynamics, or resistance). Unexpected treatment failure and/or severe adverse effects can occur if these factors are not considered. Toxicity avoidance and enhancement of clinical efficacy are the best approach to optimize the benefit/risk ratio of therapy with antibacterial drugs.
