The British Thoracic Society has published guidelines for the

empirical treatment of severe CAP (Table 1). This is defined as the presence of signs and symptoms of pneumonia in a previously healthy patient due to an infection acquired outside the hospital environment, associated with a CURB-65 score of three or more.1-3 Treatment is directed against common, community-acquired pathogens – Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, Mycoplasma pneumoniae, Legionella species and, occasionally, gram-negative enteric bacilli.4,5 At the doses recommended, penicillins remain effective despite increasing resistance of S. pneumoniae.1 Antibiotics are given for a period of 10 days, or for 14-21 days in cases caused by Legionella, S. Aureus or gram-negative enteric bacilli. For young children, treatment with co-amoxiclav or a cephalosporin is sufficient. Addition of a macrolide is only necessary for those aged five years and above, in whom mycoplasma pneumonia is more common.2 Hospital-acquired and ventilator-associated pneumonia (HAP and VAP) Early-onset HAP/VAP, in patients who have not received antibiotics, is often caused by community-acquired organisms.6,7 Pneumonia developing after five or more days in hospital or following antibiotic administration is more likely to be caused by potentially antibiotic-resistant organisms, including Pseudomonas aeruginosa, Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus (MRSA). Guidelines for the empirical treatment of HAP/VAP have been produced by the Infectious Diseases Society of America, and draft guidance by a working party of the Britis