title: High rate of false-negative results of the rectal swab culture method in detection of gastrointestinal colonization with vancomycin-resistant enterococci.
abstract: The diagnostic accuracy of the rectal swab (RS) culture method in identifying gastrointestinal colonization with vancomycin-resistant enterococci (VRE) is not known. Serial quantitative stool cultures, skin cultures, and RS cultures were performed for patients with VRE infections to assess the false-negative rate of the RS and the prevalence of skin colonization, a prerequisite for cross-transmission, at varying VRE stool densities. A total of 35 stool samples were obtained from 13 patients. The sensitivity of the RS culture was 58%; it ranged from 100%, at VRE densities of > or =7.5 log10 colony forming units (cfu) per gram of stool, to 0%, at densities of < or =4.5 log10 cfu per gram of stool. Skin colonization was detected at these low VRE stool densities, but it was more common at higher VRE densities (P<.001). Antibiotic exposure was significantly associated with higher VRE stool densities (P<.001). The high false-negative rate of the RS may be contributing to the continued increase in the prevalence of VRE.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Vanderbilt University School of Medicine, Nashville, TN, USA. edagata@caregroup.harvard.edu
authors.forename: Erika M C
authors.initials: EM
authors.lastname: D'Agata
authors.forename: Shiva
authors.initials: S
authors.lastname: Gautam
authors.forename: William K
authors.initials: WK
authors.lastname: Green
authors.forename: Yi-Wei
authors.initials: YW
authors.lastname: Tang
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods / Q000592:standards; D004334:Drug Administration Schedule; D016983:Enterococcus / Q000302:isolation & purification* / Q000378:metabolism*; D013293:Enterococcus faecalis / Q000302:isolation & purification / Q000378:metabolism; D016984:Enterococcus faecium / Q000302:isolation & purification / Q000378:metabolism; D005188:False Negative Reactions; D005243:Feces / Q000737:chemistry / Q000382:microbiology; D005767:Gastrointestinal Diseases / Q000382:microbiology*; D016908:Gram-Positive Bacterial Infections / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012007:Rectum / Q000382:microbiology*; D012680:Sensitivity and Specificity; D012867:Skin / Q000382:microbiology; D014640:Vancomycin / Q000008:administration & dosage / Q000378:metabolism / Q000627:therapeutic use*; D020713:Vancomycin Resistance
chemical_list: D014640:Vancomycin