The Identification of Genetically Related Bacterial Isolates Using Pulsed Field Gel Electrophoresis on Nursing Home Units: A Clinical Experience: BACTERIAL TRANSMISSION IN THE NURSING HOME

OBJECTIVES: To describe a laboratory-based technique to track nursing home infections. DESIGN: Retrospective data analysis. SETTING: A 721-bed skilled care facility with 14 nursing units. PARTICIPANTS: Residents in a nursing home, average age 76 +/- 10, 78% male. MEASUREMENTS: Bacterial isolates were listed for each nursing unit. Clusters of identical species and antibiotic susceptibility were identified followed by pulsed-field gel electrophoresis (PFGE). If the genetic analysis yielded related strains, the director of nursing performed a clinical investigation. PFGE is available through reference laboratories at a cost of approximately $75/isolate. RESULTS: Twenty-four clinical clusters of phenotypically identical bacteria (species, antibiotic susceptibility) were identified. Fourteen included genetically related isolates. CONCLUSION: Approximately half of the phenotypically identical clusters contained genetically related isolates. The identification of genetically related bacterial isolates on nursing units by PFGE provides staff with a specific circumstance to review secretion precautions. Genetic analysis may also demonstrate that apparent clusters are unrelated.