It is well established that ICUs tend to harbor a more resistant collection of infections than elsewhere in the hospital and the reasons for this are complex.5, 6 Many of the patients on the ICU have prior prolonged hospital stay, immunosuppression, and antibiotic exposure, all of which will predispose to carriage of multiresistant organisms on admission to the ICU.7 Once there they are often subjected to further intensive use of antibiotic and poor adherence to control of infection procedures. These will select for and spread further resistance, often in the form of multiresistant clones that colonize other patients, staff, and the environment of the ICU including items of equipment such as ventilators.8, 9 Such epidemic or indeed endemic organisms frequently include methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant ente-rococci (VRE), Acinetobacter spp, and extended spectrum p-lactamase-producing Enterobacteriaceae (ESBL).10-13 The epidemiology and control of such multire-sistant organisms has been the subject of many previous publications and is not within the scope of this review. Suffice to say, they continue to plague many ICUs causing major problems.
Another area that has not received much attention but that is crucial to the control of these multiresistant strains is the intensity of antibiotic use in ICUs. This can be severalfold higher than hospital use as a whole with 200-400 defined daily doses (DDD) per 100 occupied bed days not uncommon.14, 15 Not only is total antibiotic use intense, but the ICU is likely to be the highest user of the newest, broad-spectrum agents and double and triple antibiotic combinations are often the norm in such patients. A vicious circle of increasing resistance necessitating the prescription of ever more broad spectrum drugs perpetuates the problem until untreatable infections become a real prospect.
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