I am very happy to accept the translators' invitation to write a few lines of introduction to this book. Of course, there is little need to explain the author. Pauli's first famous work, his article on the theory of relativity in the Encyklopadie der Mathematischen Wissenschaften was written at the age of twenty. He afterwards took part in the development of atomic physics from the still essentially classical picture of Bohr's early work to the true quantum mechanics. Thereafter, some of his work concerned the treatment of problems in the framework of the new theory, especially his paper on the hydrogen atom following the matrix method without recourse to Schrodinger's analytic form of the theory. His greatest achievement, the exclusion principle, generally known today under his own name as the Pauli principle, that governs the quantum theory of all problems including more than one electron, preceded the basic work of Heisenberg and Schrodinger, and brought him the Nobel prize. It includes the mathematical treatment of the spin by means of the now so well known Pauli matrices. In 1929, in a paper with Heisenberg, he laid the foundation of quantum electrodynamics and, in doing so, to the whole theory of quantized wave fields which was to become the via regia of access to elementary particle physics, since here for the first time processes of generation and annihilation of particles could be described for the case of the photons.

Tuberculosis (TB) is the major cause of death worldwide. The enormity of the problem has been further worsened by the emergence of multi-drug resistant (MDR) strains and the dual infection with HIV. A newly identified TB threat which leaves patients virtually untreatable using currently available anti-TB drugs is XDR-TB. Fluoroquinoloes are increasingly being used in the treatment of mycobacterial infections especially, tuberculosis and leprosy. Ciprofloxacin is an antibiotic that is used to treat bacterial infections. Ciprofloxacin stops the multiplication of bacteria by inhibiting the reproduction and repair of their genetic material (DNA). Ciprofloxacin is used to treat infections of the skin, lungs, airways, bones, and joints caused by susceptible bacteria. Although the primary mechanism of their action is by inhibiting gyrase, other possible mechanisms can not be ruled out. The mechanism of quinolone resistance involves primarily mutations in the A and B subunits of the DNA gyrase. Another mechanism of resistance to quinolones is the efflux of the drug out of the cell. It is possible that fluoroquinolones may have some other mechanisms of action also.