Culture of the Entire Mouse to Determine Whether Cultivable Borrelia Burgdorferi Persists in Infected Mice Treated with a Five-day Course of Ceftriaxone

Although controversial, it has been suggested that antibiotic treatment of laboratory animals infected with Borrelia burgdorferi often leads to the persistence of residual spirochetes that are claimed to be viable but noncultivable. If viable cells of B. burgdorferi do persist following antibiotic therapy, one possible explanation for the lack of cultivability is that too few organisms persist in any given tissue site that might be sampled and cultured. In this study, we treated SKH (hairless) mice, with B. burgdorferi infection of 3 months' duration, with either ceftriaxone or saline for 5 days and then cultured a suspension extract of nearly the entire mouse using a combined in vivo/in vitro culture method. All of the saline-treated (control) mice were culture positive, compared with none of the antibiotic-treated mice. Our findings further document the effectiveness of antibiotic therapy in eradicating cultivable cells of B. burgdorferi, irrespective of tissue or organ site.