A 40-year-old, moderately obese man presents with a persistent productive cough. The cough has been present for several weeks, but recently the man noted that his sputum has assumed a greenish color. Fuher questioning elicits a history of productive cough, usually in the winter months, over the past several years. He has smoked two packs of cigarettes per day since he was 16 years old. On examination, the man is febrile (100deg F), and coarse rhonchi and wheezes can be appreciated bilaterally. Which of the following is the MOST likely diagnosis?