[When pneumonia does not respond to antibiotic therapy]

The favorable pneumonia outcome with antibiotics according to the recommendations is defined by improving clinical symptoms in 48-72 hours followed by their normalization within less than 10 days. This is different to stop progression of radiological abnormalities that can be delayed for 48-72 hours and moreover to radiological normalization which may require 4 to 8 weeks. The non favorable outcome, 48-72 hours after a first line of antibiotic therapy results in the vast majority of cases, from an infection: the pneumonia is not or poorly treated. The non favorable outcome 5-6 days after two successive lines of antibiotic therapy may also result from a non infectious cause: immunologic, toxic or tumoral pneumonitis. Practitioner dilemna is not to worry too early (slow-resolving pneumonia with clinical cure in normal time but slow radiological resolution) or too late (non-resolving pneumonia with no clinical cure and persistence or radiological extension).