To serve its primary function of gas exchange, the lung is the organ with the largest epithelial surface area in continuous contact with the external environment. The upper and lower airways of humans are repeatedly exposed to airborne particles and microorganisms. Infectious respiratory disorders are therefore an important part of our daily activities as practising physicians. Furthermore, the management of these infectious diseases continues to evolve. Physicians are continuously confronted with new challenges in the cost-effective management of these infectious diseases. Antibiotic treatment is a key factor in the treatment schedules of these diseases. Optimal treatment would be an antibiotic regimen specifically suited for a specific patient, the type of infection and the infecting pathogen to assure an optimal therapeutic outcome. The present issue of the Monograph not only covers basic knowledge about treatment with antibiotics but also provides state of the art information about a variety of different classes of antibiotics.