Pulsed-field gel electrophoresis for the analysis of Listeria monocytogenes infection clusters after kidney transplantation

Listeria monocytogenes causes a rare, life-threatening infection in recipients of transplanted organs. We used cultures of blood and cerebrospinal fluid to characterize isolates and to distinguish cases in dusters from what might have been sporadic cases. From December 1994 to November 1995, six systemic L.monocytogens infections occurred at our transportation unit. We confirmed the clinical diagnosis with blood and cerebrospinal fluid cultures and characterized the isolates retrospectively with pulsed-field gel electrophoresis (PFGE), phage-typing, and serotyping. We also performed an environmental investigation (food, drug, and stool). We took samples after the first two L. monocytogenes infections and then after cases three and four occurred. All patients recovered completely, and no graft was lost. Four patients had identical or genetically related L. monocytogenes isolates in PFGE (type A) and serotyping (type 1/2b). The other two had PFGE type B and G. L. monocytogens was not detected in food or drug samples from patients on the renal- transplantation ward or in stool samples from the ward staff. It was concluded that PFGE allows sporadic cases and cluster cases of L. monocytogenes infection to be distinguished.