Antibiotic stewardship

Merriam-Webster's online dictionary defines stewardship as "the careful and responsible management of something entrusted to one's care." As evidence linking antibiotic misuse and resistance has accumulated, a primary focus of antibiotic stewardship has been to limit inappropriate antibiotic prescriptions in the inpatient setting. Several stewardship strategies, which intercede at various points in the prescription process, have been reviewed recently (Figure 9.14; MacDougall and Polk, 2005).

Figure 9.14 Antimicrobial prescribing process and antimicrobial stewardship strategies. From MacDougall and Polk (2005).

Formulary restrictions have been used successfully to reduce rates of antibiotic resistance. Spurred on by a desire to reduce hospital antimicrobial expenditures, as well as a need to halt a resistant Acinetobacter bloodstream infection outbreak, Ben Taub County Hospital in Houston initiated a formulary restriction program in 1994. They required infectious disease approval before prescribing amikacin, ceftazidime, ciprofloxacin, fluconazole, ofloxacin, ticarcillin/clavulanate, or piper-icillin/tazobactam. By encouraging selection of less expensive antibiotics, without reducing overall quantity of antibiotic prescribing, the restriction led to a $430,000 (32 percent) decrease in expenditures for parenteral antimicrobial agents during a six-month period. The restrictions also led to increased rates of antimicrobial susceptibility - for example, rates of susceptibility for E. colito ticarcillin/clavulanate increased from 77 to 97 percent for ICU patients. Although some have raised concerns that antibiotic restrictions may worsen clinical outcomes by hindering a clinician's ability to immediately prescribe broad-spectrum antibiotics, this study showed equivalent or better patient outcomes during the restriction period; survival rates for bacteremic patients did not change, nor did time to administration of appropriate antibiotic therapy (White et al., 1997).

Antibiotic restrictions limited to even a single unit can make a difference. In an attempt to decrease rates of quinolone-resistant Pseudomonas aeruginosa, ICU staff from a French hospital limited use of fluoroquinolones during a six-month period. Quinolone use decreased from 330 to 80 DDD per 1000 patient-days, and rates of quinolone resistance among Pseudomonas isolates decreased from 71 to 52 percent. Although unexpected, MRSA rates also fell from 30 percent to 18 percent (Aubert et al., 2005).

Physician computer order-entry systems can bring automation to antibiotic stewardship. Computer systems may prompt prescribing physicians with regard to national guidelines, local resistance patterns, drug interactions, and indications for use (Weinstein, 2001). A group from Utah described antibiotic prescribing outcomes during use of an advanced physician order-entry system that linked directly with patients' microbiology records to make prescribing recommendations. During a one-year intervention, ICU physicians used the anti-infectives order-entry system for all patients. The system led to fewer orders for drugs to which the patients had reported allergies, improved drug dosing, lessened antibiotic susceptibility - drug choice mismatches (from 206 before to 12 during intervention), and reduced anti-infective costs, total hospital costs, and length of hospital stay (Evans et al., 1998).

Health systems also have successfully instituted outpatient antibiotic stewardship programs to reduce inappropriate prescribing for URIs. Educational efforts directed at rural Utah physicians successfully reduced prescribing for URIs by 15 percent, with a 56 percent decrease in antibiotic prescriptions for acute bronchitis (Rubin et al., 2005). A randomized controlled trial of the effects of a multi-faceted educational intervention aimed at reducing antibiotic prescriptions for URIs provided educational materials to patients, and pharmaceutical industry-style academic detailing and feedback of practice prescribing profiles for clinicians. During the intervention period there was a substantial reduction in rate of antibiotic treatment of acute bronchitis, from 74 percent to 48 (Gonzales et al, 1999).

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