[Frontiers in Bioscience 11, 2028-2034, September 1, 2006]

Mycoplasma hominis and Trichomonas vaginalis: a unique case of symbiotic relationship between two obligate human parasites

Daniele Dessì, Paola Rappelli, Nicia Diaz, Piero Cappuccinelli, and Pier Luigi Fiori

Department of Biomedical Sciences, Division of Microbiology, University of Sassari. Viale S.Pietro 43/B 07100 Sassari, Italy

TABLE OF CONTENTS

1. Abstract
2. Introduction
2.1. The relationships between protozoa and bacteria
2.2. Mycoplasma hominis and Trichomonas vaginalis: two sexually transmitted human pathogens
3. The biological association between Mycoplasma hominis and Trichomonas vaginalis
4. Conclusions and perspective
5. Acknowledgements
6. References

1. ABSTRACT

Mollicutes are the smallest and simplest self-replicating microorganisms. Despite the minimal genome and apparent lack of complexity, mycoplasmas show a high degree of adaptation to the most diverse environments. Mycoplasma hominis is a human sexually transmitted mycoplasma which is able to establish a biological association with Trichomonas vaginalis, a pathogenic flagellated protist. M.hominis and T.vaginalis share the same specific natural niche, the human genitourinary tract. Symbiotic relationships between unicellular eukaryotes and bacteria are well known and have been extensively studied, providing interesting insights into the biology of one or both the symbionts. The relationship between T.vaginalis and M.hominis is unique in that it was the first described association of two obligated human parasites. Several aspects of this relationship have been investigated, showing how the trichomonad may be viewed not only as a new niche for M.hominis, but also as a "Trojan horse" for the transmission of the bacterial infection to the human host.