ACKNOWLEDGEMENTS

All appreciation is for almighty God, the most merciful, who granted me the wisdom, strength and perseverance to finish this seemingly impossible work. I am indebted to my thesis supervisor Professor Jean-Louis Mège who, from conception of idea to the completion of thesis, generously guided me. I could not have imagined having a better advisor and mentor for my PhD. I have faced many tough times during my thesis project and successfully tackled all the problems mainly because of his guidance, encouragement and emotional support, without which I could not have come at this stage. The scientific and professional approach I learnt from him will be the guiding principle throughout my career. I am obliged to my laboratory leader Professor Didier Raoult, a renowned scientist in clinical microbiology, for the continuous financial and logistic support for the research. The working atmosphere at URMITE enriched my scientific ideas. The knowledge he has imparted, and the patience he has displayed was vital to the completion of this thesis. I would like to express my sincere gratitude to Dr. Christian Capo who has always been my side whenever I was in need, especially for writing papers, thesis and draftin