We're swimming in a sea of antibiotics. Expenditures for anti-infectives in non-federal hospitals were the third highest among all classes of pharmaceutical agents in 2009 and overall, antibiotics are reported to be the second most frequently prescribed class of pharmaceuticals. Approximately 40% of hospitalized patients receive an antibiotic during their inpatient stay. In 2010 in the outpatient setting, an average of 0.8, that is almost one, antibiotic prescriptions were written for each person in the US. One would think that we are all constantly suffering from bacterial infections. If this were true, one may wonder how the human race failed to become extinct before the availability of antibiotics. In fact however, as much as one half of antibiotic use is inappropriately prescribed. There are a number of reasons that an antibacterial prescription may be considered inappropriate. These include the absence of a bacterial infection or indication for prophylaxis, or a violation of one of or more of the following ''Ds'' of optimal antimicrobial therapy, that is the right drug, the right dose, the best route of delivery, attention to de-escalation, and the appropriate duration of administration. Inappropriate use is associated with poor patient outcomes, including adverse drug reactions, organ toxicity, superinfection, for instance due to clostridium difficilly, selection of antibiotic resistance, and in critical care patients, increased mortality. It also results in excess costs, not only drug acquisition costs but costs accruing from the management of complications, prolonged hospital stays, and costs associated with the emergence of antibiotic resistance. The emergence of resistance is increasingly problematic since the development of novel effective antibiotics is almost ground to a halt, antibiotics are a precious resource. Antimicrobial stewardship represents an optimized approach to improve patient care and a sustainable antibiotic future. In a joint statement, the Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America and the Pediatric Infectious Diseases Society described antimicrobial stewardship in this way: ''Antimicrobial stewardship refers to coordinated interventions designed to improve and measure the appropriate use of antimicrobial agents by promoting the selection of the optimal antibiotic drug regimens including dosing, duration of therapy and route of administration. The major objectives of antimicrobial stewardship are to achieve best clinical outcomes related to antimicrobial use while minimizing toxicity and other adverse events, thereby limiting the selective pressure on bacterial populations that drives the emergence of antimicrobial resistant strains. Antimicrobial stewardship may also reduce excessive costs attributable to sub-optimal antimicrobial use.'' Empiric evidence indicates that antimicrobial stewardship programs are in fact associated with a significant optimization of antibiotic use, a reduction in the incidence of infection with antibiotic resistant pathogens, reduce hospital length of stay, and reduce drug acquisition costs. The tactics utilized by antimicrobial stewardship programs commonly include the following: clinician education, formulary optimization, antibiotic use restrictions, prospective audit with intervention and feedback, optimization of dosing and administration, streamlining that is for instance de-escalation and elimination of redundant combination therapy, early switch from intravenous to oral route of administration, appropriate duration of antibiotic therapy, and implementation of site-specific treatment pathways based on clinical guidelines. Effective implementation of these and other strategies necessarily involves a collaborative effort between colleagues with special knowledge of infectious diseases, pharmacy, infection control and prevention, clinical microbiology, information technology and healthcare administration. The strategies themselves must be based on the clinical science underlying the principles of appropriate antibiotic use. These principles are in turn based on knowledge of mechanisms of action and a resistance to antibiotics, the pharmacodynamics and pharmacokinetics, and potential for adverse effects including collateral damage, and inally, the available clinical trial evidence demonstrating therapeutic benefit.