Objective: Determining the microbial cause of cellulitis is often difficult. In this study, a novel two-needle lavage technique was used to culture Borrelia burgdorferi from the skin of suspected erythema migrans lesions.
Design: The yield of lavage cultures for B burgdorferi was compared with that of a 2-mm skin biopsy sample.
Setting: A Lyme disease diagnostic center located in an area in which Lyme disease is epidemic.
Patients: Forty-five patients with suspected erythema migrans who had not been treated with antimicrobial agents.
Intervention: Cutaneous lavage of the advancing edge of a suspected primary erythema migrans lesion was done for all 45 participants, 33 of whom also had a skin biopsy of the same lesion at an identical (14) or an adjacent (19) site.
Main outcome measures: Growth of B burgdorferi in in vitro culture.
Results: Lavage fluid cultures grew B burgdorferi in 13 (29%) of the 45 cases (95% confidence interval [CI], 16% to 44%). Among the 33 cases in which both lavage and skin biopsy cultures were done, the yield of lavage culture was less than that of biopsy culture (P less than .09, 12/33 vs 20/33). If contaminated cultures are excluded, this difference is significant (P less than .05, 12/30 vs 20/27).
Conclusion: Cutaneous lavage is a new diagnostic technique for recovery of B burgdorferi from erythema migrans lesions that has potential applicability to other types of cutaneous infections.