Or...Search this site Home Symptoms Live Discussion Diagnosis Treatment Area Support Library Research Lymelinks Contact Pets & Lyme DONATIONS Drug Info Medical Dictionary Board of Directors      Click on the graphic to vote for this site as a Starting Point Hot Site. -- No Warranties or Representations The data and information presented in this web site are presented in good faith and believed to be accurate. Any and all liability for the content or any omissions including any inaccuracies, errors, or misstatements in such data or information is expressly disclaimed. The web site is compiled for the sole purpose of informing community members of resources and information pertaining to Lyme Borreliosis Disease and its coinfections. The Canadian Lyme Disease Foundation, Directors and members are not liable for any direct or indirect damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action arising out of or in connection with the use or performance of information available from this website. Consult a qualified Lyme ( Borreliosis ) Disease literate doctor for medical advice if Lyme Disease is suspect. en français For Physicians Ticks Coinfections Prevention Our Stories Click Here to order our free Lyme Disease Flyer,    Here for our free Lyme Disease Poster ..documents may be copied (to distribute) but edit only for alignment. Dipartimento di Scienze Biomediche, sez. Microbiologia, Universita degli Studi di Trieste, Trieste, Italy. rmurgia@dsbmail.units.it It has been demonstrated recently that cells of Borrelia burgdorferi sensu lato, the etiological agent of Lyme disease, transform from mobile spirochetes into nonmotile cystic forms in the presence of certain unfavourable conditions, and that cystic forms are able to reconvert to vegetative spirochetes in vitro and in vivo. The purpose of this study was to investigate the kinetics of conversion of borreliae to cysts in different stress conditions such as starvation media or the presence of different antibiotics. Using the same experimental conditions we also investigated the possible role in cyst formation of RpoS, an alternative sigma factor that controls a regulon in response to starvation and transition to stationary phase. We observed that beta-lactams penicillin G and ceftriaxone, the antibiotics of choice in Lyme borreliosis treatment, favoured the production of cysts when used with serum-depleted BSK medium. In contrast, we observed a low level of cyst formation in the presence of macrolides and tetracyclines. In order to elucidate the role of the rpoS gene in cyst formation we analyzed the reaction of the rpoS mutant strain in comparison with its wild-type in different conditions. Under the same stimuli, both the wild-type borrelia and the rpoS knock-out isogenic strain produced cystic forms with similar kinetics, thus excluding the participation of the gene in this phenomenon. Our findings suggest that cyst formation is mainly due to a physical-chemical rearrangement of the outer membrane of Borrelia burgdorferi sensu lato leading to membrane fusion and controlled by different regulation mechanisms.