The identification of genetically related bacterial isolates using pulsed field gel electrophoresis on nursing home units: a clinical experience.

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 dollars/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.