26
Selection of Antibiotics in Critical Care
Divya Ahuja
Department of Medicine, University of South Carolina School of Medicine, Columbia, South Carolina, U.S.A.Benjamin B. Britt and Charles S. Bryan
Providence Hospitals, Columbia, South Carolina, U.S.A.INTRODUCTION
In most hospitals the numbers of immune compromised and acutely ill patients requiring
admission to the intensive care unit (ICU) continue to increase. A portion of these patients
present with life-threatening community-acquired infections, but all of them are susceptible to
hospital-acquired infections on account of such necessary interventions as multiple vascular
access lines, hemodynamic monitoring devices, mechanical ventilation, urethral catheter-
ization, surgery, and trauma management. Most ICU patients exhibit at least some
manifestations of the systemic inflammatory response syndrome (SIRS), and a fraction of
these will have infection (sepsis). Aggressive empiric antimicrobial therapy necessarily
becomes an almost routine aspect of ICU care, and indeed has been shown to improve
survival. The familiar downsides include adverse drug reactions, colonization, and super-
infection by opportunistic pathogens, cost, and—of global importance—emergence of
increasingly difficult-to-treat drug-resistant strains. The purpose of this chapter is to review
some principles pertaining to antibiotic selection.
A MULTIDISCIPLINARY TEAM APPROACH
Two organizational trends impact favorably on the potential to make empiric antimicrobial
therapy in the ICU more “rational” than it has been in the past. The first of these, encouraged
by leaders of the patient safety movement including the Leapfrog Group (a consortium of
Fortune 500 companies representing health care purchasers and federal and state agencies), is
the trend for ICU patients to be managed by full-time intensivists—that is, physicians with
special training and experience in ICU care (1). The second trend, likewise encouraged by the
patient safety movement and endorsed by the Infectious Diseases Society of America (IDSA),
consists of the increasing role of multidisciplinary teams in various aspects of health care
delivery. Such teams enhance the likelihood that the major principles for setting guidelines for
antimicrobial use, which have been recognized for several decades, will indeed be honored in
practice (2).
The IDSA guidelines for such a multidisciplinary core team call for an infectious diseases
(ID) physician, an ID pharmacist, a clinical microbiologist, an information systems specialist,
an infection control practitioner, an epidemiologist, and an intensivist, where ICUs are
concerned (3). At some institutions, interested ID pharmacists will assume team leadership
and at others, it may be the ID physicians or the intensivists themselves (4). Independent of
institution setting, endorsement from hospital administration is essential to ensure sufficient
authority, define program outcomes, and obtain necessary infrastructure, but the overarching
desideratum is to achieve “buy-in” among all prescribing physicians. A multidisciplinary team
should focus especially on (i) the evolving medical literature on effective approaches to
antimicrobial therapy in the ICU, including new drug developments; (ii) local experience
pertaining to ICU pathogens and their antimicrobial susceptibility patterns; and (iii) methods
for improving and streamlining prescribing practices. Such methods include computer-based
surveillance, formulary restriction and preauthorization, prospective audit with intervention
and feedback, and continuing medical education (3,5).