Over the last several years, a number of investigators5–7 have documented that the pathogens infecting patients coming from the health-care associated (HCA) environment may be different from the pathogens seen in patients from other populations who have been admitted to the hospital from the community. In fact, because of their contact with the health-care environment, these patients may already be colonized with drug-resistant pathogens, importing these organisms at the time of admission to the hospital. For example, in one study of 383 patients with methicillin-resistant Staphylococcus aureus (MRSA) infections, 123 organisms were isolated from patients who had been in the hospital < 48 h, and only 1 of these was a true community-acquired isolate.,5The remainder of patients were from long-term care facilities (21 patients) or had been recently hospitalized or treated in an outpatient facility (94 patients), while the rest had received dialysis or visiting nurse care, or had undergone day surgery. In another study of 1,100 MRSA infections, 85% were health-care–related.6In this study, the definition of HCA infection was a history of hospitalization, surgery, dialysis, or residence in a long-term care facility within a year of contracting the infection, or the presence of a permanent indwelling catheter or percutaneous medical device (eg, gastrostomy, tracheostomy, or Foley catheter). This pattern of patients with HCA infection bringing multidrug-resistant (MDR) pathogens with them to the hospital, also applies to enteric Gram-negative organisms. In a 6-year study7 of patients who harbored MDR Gram-negative organisms in clinical cultures collected within the first 48 h of hospital admission, the prevalence of isolates rose for Escherichia coli, Klebsiella species, and Enterobacter cloacae, but not for Pseudomonas aeruginosa, which remained a common pathogen during the entire period. Fifty-three percent of these isolates were resistant to three antimicrobial groups, and 12% were resistant to five antibiotic classes. The risk factors associated with infection with these pathogens were as follows: prior exposure to antibiotics; prior residence in a long-term care facility; and age ≥ 65 years.