Is bronchitis a bacteria infection or a viral infection?

Both: It can be due to either or. Most cases of infectious bronchitis are due to viruses though, and will not respond to antibiotics.

Depends: Bronchitis is an inflammatory condition of the bronchial tubes. It can be broken down to infectious or non-infectious. Infectious causes include bacterial, viral and rarely fungal. Most commonly in an otherwise health adult, most bronchitis is viral (i.e. Untreatable with antibiotics.) non-infectious causes include allergens (pollens, molds, etc.) and irritants (smoke, chemicals, etc.).

Either...: Acute bronchitis could be due to either a bacterial or viral infection whereas chronic bronchitis, a form of copd, is due to smoking.