Addressing Antimicrobial Resistance in the Intensive Care Unit*

Two of the more common strategies for optimizing antimicrobial therapy in the intensive care unit (ICU) are antibiotic cycling and de-escalation. Antibiotic cycling involves scheduled replacement of 1 or more antibiotics with another for a period of time, in order to avoid the development or control the rate of bacterial resistance. The data to support antibiotic cycling are sparse; its practice is supported more by theory, mostly among physicians in ICUs and pharmacists. Many of the positive results of published studies of cycling can be explained by differences in antibiotic usage or resistance levels at baseline. Also, recent data show an important and unintended consequence of cycling—reducing resistance to 1 drug while developing resistance to its replacement. De-escalation involves an aggressive empiric therapy to cover the potential high minimum inhibitory concentration pathogens (eg, frequently Pseudomonas or Acinetobacter in the ICU). At 48 hours, reassessment helps to narrow down the therapeutic options to provide more specific antibiotic coverage, using a less toxic—and often less expensive—drug with a narrower spectrum. The data to support de-escalation are not widely available. Antibiotic cycling and de-escalation are both widely practiced in ICUs on an ad hoc basis. More careful clinical studies to assess these algorithms are under way. (Adv Stud Med. 2004;4(4A):S256-S261) S epsis is the most common cause of death in the intensive care unit (ICU). Infectious disease specialists are looking for novel strategies to control sepsis while practicing antimicrobial stewardship in light of the ever-increasing numbers of multiresistant bacteria. Two of the more common strategies for optimizing antimicrobial therapy in this setting are cycling and de-escalation. In order to understand the rationale for these strategies, it is important to understand the mechanisms of resistance.