Acute bronchitis, as the term implies, is a lower respiratory tract syndrome and another common source of acute cough. It manifests as a persistent cough, with or without sputum production, in patients with a normal chest radiograph. Although it is much less prevalent than the common cold, acute bronchitis is the most common diagnosis given to patients presenting to a physician with acute cough. It is caused by a respiratory virus more than 90% of the time. Viral cultures and serologic assays are not routinely ordered; hence, the organism responsible is rarely identified.
A 2009 review found that the evidence supporting the effectiveness of zinc is mixed with respect to cough,  and a 2011 Cochrane review concluded that zinc "administered within 24 hours of onset of symptoms reduces the duration and severity of the common cold in healthy people".  A 2003 review concluded: "Clinical trial data support the value of zinc in reducing the duration and severity of symptoms of the common cold when administered within 24 hours of the onset of common cold symptoms."  Zinc gel in the nose may lead to long-term or permanent loss of smell. The FDA therefore discourages its use. 
So now that we understand why we may give antibiotics, the question becomes who we should give them to? Many experts argue that most patients, regardless of symptoms and lab test results, don’t need antibiotics since most acute diarrheal illnesses are self-limited. Additionally, further prescription of antibiotics will lead to increased drug resistance and side-effects. Other guidelines, including those from the IDSA and AAG, provide a more conservative approach. They state patients should receive antibiotics if they are presenting with symptoms of traveler’s diarrhea, as immediate treatment can reduce symptom duration by 2-3 days ( Guerrant, 2001 ). They further recommend antibiotic therapy in those patients with high fever (>), history suspicious of a moderate-severe bacterial infection, guiac positive stools or positive fecal WBC ( Guerrant, 2001 ). Some criticize the IDSA guidelines for relying too heavily on stool testing to decide whether or not to give antibiotics.