Direct multiplex PCR assay using vanA and vanB primers, which provides rapid results, was more sensitive than culture on selective media for samples collected by rectal swab (20 of 46 versus 8 of 46; P < 0.001) or perianal swab (17 of 58 versus 12 of 58; P ؍ 0.059) for the detection of gastrointestinal colonization by vancomycin-resistant enterococci.Since the first report of human infection with vancomycinresistant enterococci (VRE) in the late 1980s (A. H. Uttley, C. H. Collins, J. Naidoo, and R. C. George, Letter, Lancet 1:57-58, 1988), VRE have become common in many hospitals in the United States (6). One likely reason why infection control measures in hospitals have not effectively controlled VRE transmission is the unrecognized reservoir of VRE-colonized patients that contributes to transmission (1, 15). Identification and isolation of VRE-colonized patients have reduced the prevalence of VRE colonization both within a facility (7) and for an entire geographic region (10).Screening patients for gastrointestinal VRE colonization using culture requires 48 to 72 h of incubation and testing (12). Since the median length of stay for hospitalized patients in the United States in 1999 was 5 days (11), culture may not yield results during a patient's hospital stay. However, the results of PCR assays to detect vancomycin resistance genes vanA and vanB can be obtained within 8 h (12). Thus, the use of PCR to screen patients should enable early implementation of contact isolation precautions, which can improve VRE infection control efforts.(This work was presented in part at the 11th Annual Scien- Swab specimens were suspended in 350 l of sterile water, and 50-l aliquots were used for DNA extraction or plated onto Enterococcosel (BBL) medium containing 6 g of vancomycin (Sigma, St. Louis, Mo.) per ml. Isolates were identified as Enterococcus faecium or Enterococcus faecalis by standard biochemical methods (5), and their agar dilution susceptibility was tested following National Committee for Clinical Laboratory Standards guidelines (9). DNA was extracted using the MasterPure DNA purification kit (Epicentre Technologies, Madison, Wis.) with the following modifications: 50 l of lysozyme (100 mg/ml; Sigma) was added to the 50-l aliquot and incubated at 37°C for 30 min, and 100 g of proteinase K was used. The final DNA pellet was suspended in 50 l of sterile water, and 5 l was used in a 50-l hot-start PCR mixture containing 0.4 M (each) primer for the vanA and vanB genes (4) and 1ϫ Platinum PCR Supermix (Invitrogen, Carlsbad, Calif.) for the samples collected in 2000 or 1ϫ AmpliTaq Gold PCR Mastermix (Applied Biosystems, Foster City, Calif.) for the samples collected in 2001. DNA extraction controls, i.e., water for the negative control and a vanB-containing E. faecium for the positive control, and PCR controls, i.e., vancomycin-susceptible E. faecium for the negative control and vanA-containing E. faecium for the positive control, were processed during each run. The amplification program consisted of the following: (i...
