The chest x-ray shows extensive airspace opacity with air bronchogram in the right mid to lower zones.

In the context of recent travel, fever with respiratory and gastrointestinal symptoms, this patient is likely to have Legionella Pneumonia and subsequent investigations confirmed Legionella etiology.

The preferred antibiotic to treat Legionella pneumonia in this unwell patient is IV Azithromycin (as per Therapeutic Guidelines). This patient should also have broad spectrum IV antibiotic until Legionella is confirmed as the causative organism.