[Lung infections with atypical features].

The clinical difference between a lobar pneumonia caused by pneumococci or other bacterial agents and lower respiratory tract infections presenting with atypical symptoms is important. Mycoplasma pneumoniae, chlamydia species, Coxiella burnetii and several viruses amongst others are micro-organisms which cause atypical symptoms. All the time new types of micro-organisms like Ureaplasma urealyticum are found as a cause of pneumonia with atypical symptoms. Special diagnostic tools like cultures, serological or antigen detection are often needed to determine the exact causative agent. Clinical data are important to suspect a specific micro-organism.