Surveillance of intestinal colonization and of infection by vancomycin-resistant enterococci in hospitalized cancer patients

Objective: To study epidemiologic features of and risk factors for intestinal colonization and infection by vancomycin-resistant enterococci (VRE) in cancer patients.Methods: During a 41-month period, over 7600 fecal samples and all samples from sterile sites from hospitalized cancer patients were screened for VRE. Species were identified and isolates analyzed by pulsed-field gel electrophoresis (PFGE) of Smal DNA restriction fragments. Antibiotic resistance was characterized by MIC determinations, and polymerase chain reaction for vanA, vanB, and vanC1 genes. Plasmid contents were analyzed before and after Pstl and Hindlll restriction, and by Southern hybridization with a vanA probe. Two case-control studies were performed to identify risk factors for colonization or infection by VRE, respectively.Results: Eighty-two isolates were recovered from 81 patients. Most (72%) isolates were Enterococcus faecium VanA/vanA, with 37 different PFGE types, each of which was found in only one to four patients, except for type P1, which was found in 20 patients hospitalized over a 3-month period in the pediatric wards. Plasmid analysis suggested that only two types of plasmid were carrying gene vanA, as part of a transposon related to transposon Tn 1546 from reference strain E. faecium BM4147. Seventy-seven patients were colonized during the study period. Six of them became infected. Four patients were infected but not colonized. Only one patient died during the course of infection, but intestinal colonization persisted for months in the survivors. Case-control analysis revealed that cephalosporin treatment was a significant risk factor for colonization. No significant risk factor for infection was found in colonized patients.Conclusion: Colonization by VRE was mostly endemic and the colonized patients were not often infected. However, when clustered cases of colonization occurred, they were then associated with an increased rate of infection

La conquête de la montagne : des premières occupations humaines à l’anthropisation du milieu

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