Before birth, the fetus is living and developing in the sterile environment of the womb. The fetus is protected against infection by mechanical barriers like placenta and membranes and it benefits from maternal immunity. At birth, the newborn is readily colonized with micro-organisms of the birth canal and is confronted with a range of micro-organisms in the outside world. From that time onward, the neonate has to rely on the function of the immune system with additional protection of the mucous membranes and skin as essential barriers against hostile micro-organisms. Common neonatal infections are listed in Table 9.1. Most of these topics are discussed extensively in other chapters as well. In the neonatal period, defined as the age from birth to 4 weeks, acquired infections usually present with systemic symptoms and can lead to serious sequelae. The skin is frequently involved and may show petechiae, purpura, vesicles, pustules or a maculopapular rash. Many different micro-organisms may be associated (Table 9.2) although staphylococcal infections are most prominent.