What causes pneumonia with the flu Tue, Apr 13, 10 04:50PM by roman Pneumonia is a lung infection which is caused by bacteria, viruses and fungi. Pneumonia caused by viruses and bacteria are contagious. This type of pneumonia spreads quickly. TAGS: 1. causes cold flu 2. causes avian flu 3. causes death flu 4. causes h1n1 flu 5. flu vaccine causes flu