Cystic Lyme

[LymeEnigma]

Induction of cystic forms by different stress conditions in Borrelia burgdorferi

* R. MURGIA and
* M. CINCO

*Spirochete Laboratory, Dipartimento di Scienze Biomediche, Universita' degli Studi di Trieste, Via Fleming 22, 34127 Trieste, Italy

Abstract:

Cystic forms of Borrelia burgdorferi might represent a low metabolic activity state or phase of B. burgdorferi cells that allows the spirochete to survive in a hostile environment until conditions are favourable to multiply again. In this study we evaluated the rate of cyst formation induced by oxidative stress, pH variations, and heating, reconversion of cysts to vegetative forms, and some aspects of their metabolic activity. We observed cyst formation in the presence of extreme pH values, and at high temperature, but the best production of cystic forms was observed in the presence of H2O2. When transferred to BSK II medium, the cystic forms reconverted to spirochetes in relation to their age and type of induction treatment. Furthermore, we demonstrated a low metabolic activity of cystic forms by measuring amino acid incorporation. Overall, these data suggest that the phenomenon of conversion to cysts by B. burgdorferi provides a limited survival potential. This short-term survival, however, gives borreliae an additional chance to overcome unfavourable environmental conditions.

www.blackwell-synergy.com/doi/abs/10.1111/j.1600-0463.2004.apm1120110.x

[LymeEnigma]

Wien Klin Wochenschr. 2002 Jul 31;114(13-14):574-9.Links
Cystic forms of Borrelia burgdorferi sensu lato: induction, development, and the role of RpoS.
Murgia R, Piazzetta C, Cinco M.

Dipartimento di Scienze Biomediche, sez. Microbiologia, Università degli Studi di Trieste, Trieste, Italy. [e-mail]

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.

PMID: 12422604 [PubMed - indexed for MEDLINE]
www.ncbi.nlm.nih.gov/pubmed/12422604?ordinalpos=12&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum