icu

Antibiotic Rotation in the ICU

　　Restricting antibiotics is one approach to minimizing the incidence of antibiotic resistance, but decreasing the duration of antibiotic courses deserves emphasis as well. Cycling and rotation of antibiotics represent attempts to minimize resistance against one particular drug. This strategy can restore susceptibility of organisms to that one particular drug. Rahal and colleagues[2] published a before-and-after study in 1998 looking at the incidence of cephalosporin-resistant extended-spectrum beta-lactamase-producing Klebsiella during a period of time when cephalosporins were widely used. They showed that restricting the use of cephalosporins in favor of carbapenems reduced the incidence of cephalosporin-resistant Klebsiella dramatically. However, the incidence of imipenem-resistant Pseudomonas increased substantially. Rahal's approach really exchanged one type of resistance for another type of resistance. This strategy exchanges one homogeneous strategy of antibiotic use for another homogeneous strategy, rather than using a heterogeneous strategy that might not lead to so much resistance against one class of drugs.
　　Scheduled changes of drug use might be one approach to produce such heterogeneity; changes in drug use could also be made in response to changes in susceptibility patterns. Dr. Kollef[3,4] has done such a study, and found a decrease in incidence of bacteremias and nosocomial pneumonias over the first 6 months after an antibiotic policy change. However, he did not have data demonstrating that this advantage persisted for more than 6 months. Landman and colleagues[5] did a similar study between 1993 and 1996 that restricted the use of cephalosporins, vancomycin, and clindamycin in favor of ampicillin-sulbactam and piperacillin-tazobactam. The incidence of certain pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) declined, but the incidence of Acinetobacter resistant to cephalosporins increased. Thus, the restriction strategies do not always have long-term efficacy in terms of reducing total antibiotic resistance.
　　A preferable approach might be to monitor antibiotic resistance patterns in real time and to change antibiotic use based on these data. Didier Gruson and colleagues[6] have shown that this strategy can improve patient outcomes, probably by allowing clinicians to use empiric regimens that were more likely to be active against the offending pathogen (ie, allowing quicker institution of active therapy). A study reviewing 5 years of experience with this approach will be published shortly.
　　Dr. Kollef summarized by emphasizing that cycling or rotating antibiotics can be beneficial, but only if such cycling is part of a strategy of monitoring antibiotic resistance and responding wisely to changing patterns of causative organisms and antibiotic susceptibility.
Dr. Kollef was asked during the question-and-answer period whether these cycling strategies,focusing primarily on Gram-negative bacilli, could also be useful for Gram-positive organisms. Dr. Kollef replied that in the past, there were limited options for treating Gram-positive cocci, so that cycling was not really feasible. However, with the emergence of linezolid, quinupristin-dalfopristin, and perhaps daptomycin, such strategies are reasonable considerations.