Infection with multiple strains of Borrelia burgdorferi sensu stricto in patients with Lyme disease.

Objective: To assess human skin biopsy specimens from erythema migrans lesions for the presence of infection with multiple strains of the Lyme disease spirochete, Borrelia burgdorferi.
Design: Skin biopsy specimens were obtained prospectively from patients with erythema migrans. To determine allelic differences and strain identification of B burgdorferi, the biopsy specimens were analyzed by cold single-strand conformation polymorphism of an amplified fragment of the outer surface protein C (ospC) gene. Further single-strand conformation polymorphism patterns of amplified ospC genes from culture isolates were compared with polymerase chain reaction products obtained directly from erythema migrans biopsy specimens.
Setting: A private dermatology office and a university medical center outpatient department.
Patients: Sixteen patients presenting with erythema migrans.
Results: Two of the 16 patients in this cohort were infected with 2 B burgdorferi sensu stricto strains, as evidenced by 2 ospC alleles in their skin biopsy results.
Conclusion: This is the first documented description of the existence of more than a single strain of B burgdorferi sensu stricto in a human specimen.