Prior treatment with antibiotics is common in nearly all patients colonized or infected with MDR enterococci. Clindamycin, cephalosporin,aztreonam, ciprofloxacin, aminoglycoside, and metronidazole use is equally or more often associated with colonization or infection with MDR enterococci than vancomycin use. Other risk factors include prolonged hospitalization, high severity of illness score, intraabdominal surgery, renal insufficiency, enteral tube feedings, and exposure to specific hospital units, nurses, or contaminated objects and surfaces within patient-care areas.

The following persons are at an increased risk becoming infected with VRE:

• Persons who have been previously treated with vancomycin and combinations of other antibiotics such as penicillin and gentamicin.
• Persons who are hospitalized, particularly when they receive antibiotic treatment for long periods of time.
• Persons with weakened immune systems such as patients in Intensive Care Units, or in cancer or transplant wards.
• Persons who have undergone surgical procedures such as abdominal or chest surgery.
• Persons with medical devices that stay in for some time such as urinary catheters or central intravenous catheters.