Susceptibility of motile and cystic forms of Borrelia burgdorferi to ranitidine bismuth citrate Authors Øystein Brorson Department of Microbiology, Vestfold Sentralsykehus, Tønsberg, Norway Sverre-Henning Brorson Department of Pathology, Ullevål Hospital, Oslo, Norway Keywords: Borrelia burgdorferi, cystic forms, spirochetes, spheroplasts, bismuth compounds Abstract Gastrointestinal symptoms accompanying Lyme disease have not been considered in the treatment of Lyme patients yet. Here we examine the effect of ranitidine bismuthcitr ate (RBC) on motile and cystic forms of Borrelia burgdorferi in vitro, to determine whether it could cure this bacterial infection in the gastrointestinal tract. When motile forms of B. burgdorferi were exposed to RBC for 1 week at 37°C, the minimal bactericidal concentration (MBC) was >64 mg/ml. At 30°C, the MBC was >256 mg/ml. When the incubation lasted for 2 weeks at 37°C, the MBC dropped to >2 mg/ml. Bismuth aggregates were present on the surface of B. burgdorferi when RBC ≥ MBC, as shown by transmission electron microscopy (TEM). Cystic forms of B. burgdorferi, exposed to RBC for 2 weeks at 37°C, were examined by cultivation in BSK-H medium (Sigma B3528). They were stained with acridine orange (pH 6.4, pH 7.4) and studied by TEM. The MBC for RBC for young cystic forms (1 day old) and old cysts (8 months old) was estimated to be >0.125 mg/ml and >2 mg/ml, respectively. Bismuth aggregates were attached to the cysts and, in some, the pin-shaped aggregates penetrated the cyst wall. The bismuth aggregates also bound strongly to blebs and granules of B. burgdorferi when RBC ≥ MBC. When B. burgdorferi is responsible for gastrointestinal symptoms, bismuth compounds may be candidates for eradication of the bacterium from the gastrointestinal tract. Downloads PDF Published 2010-03-12 Issue Vol. 4 No. 4 (2001) Section Review Articles License Submission of a manuscript to International Microbiology implies: that the work described has not been published before, including publication in the World Wide Web (except in the form of an Abstract or as part of a published lecture, review, or thesis); that it is not under consideration for publication elsewhere; that all the coauthors have agreed to its publication. The corresponding author signs for and accepts responsability for releasing this material and will act on behalf of any and all coauthors regarding the editorial review and publication process.If an article is accepted for publication in International Microbiology, the authors (or other copyright holder) must transfer to the journal the right–not exclusive–to reproduce and distribute the article including reprints, translations, photographic reproductions, microform, electronic form (offline, online) or any other reproductions of similar nature. Nevertheless, all article in International Microbiology will be available on the Internet to any reader at no cost. The journal allows users to freely download, copy, print, distribute, search, and link to the full text of any article, provided the authorship and source of the published article is cited. The copyright owner's consent does not include copying for new works, or resale. In these cases, the specific written permission of International Microbiology must first be obtained.Authors are requested to create a link to the published article on the journal's website. The link must be accompanied by the following text: "The original publication is available on LINK at <http://www.im.microbios.org>. Please use the appropiate URL for the article in LINK. Articles disseminated via LINK are indexed, abstracted, and referenced by many abstracting and information services, bibliographic networks, subscription agencies, library networks, and consortia.