Respiratory infections caused by bacteria are often hard to distinquish from those caused by viruses. In particular, a bad case of the flu may be hard to distinquish from a bacterial infection. Bacteria will sometimes attack the weakened system of a person with a cold or the flu. (Bacterial infections sometimes follow viral infections.) The most common bacterial infections are ear infections and strep throat. Bronchitis, sinusitis, and pneumonia may be caused by bacteria Symptoms of a bacterial infection may include:

  • Fever of 104 or higher that does not reduce with two hours of home treatment.
  • Fever over 101 with shaking chills and productive cough.
  • Persistent fever. Many viral illnesses, especially the flu, cause fevers of 102 or higher for short periods of time (up to 12 to 24 hours). Call a doctor if the fever stays high:

102 or higher for two full days

101 or higher for three full days

100 or higher for four full days

  • Labored, shallow, rapid breathing with shortness of breath.
  • Sputum (mucus coughed up from lungs) is yellow, green, rust-colored, or bloody, and other symptoms (fever, productive cough, severe fatigue) are worsening. Sputum that is coughed up from the lungs is more significant than mucus that has drained down the back of the throat (postnasal drip).
  • Nasal discharge changes from clear to colored (yellow or green) after five to seven days of a cold, and other symptoms (such as sinus pain or fever) are worsening. If nasal discharge is colored from the start of a cold, call if it lasts longer than 7 to 10 days.
  • Cough that lingers more than 7 to 10 days after other symptoms have cleared, especially if it is productive (bringing up sputum). A dry, hacking cough may last several weeks after a viral illness such as a cold.
  • Ear pain that lasts more than 24 hours, or severe ear pain that lasts longer  than one hour. If the pain is severe at night, call the next morning even if the pain has stopped.
  • Localized sinus pain persists despite two to four days of home treatment, especially if nasal discharge is colored rather than clear.
  • Sore throat lasts longer than two to three days despite home treatment, and does not “act” like a cold

Antibiotics are effective against  bacterial infections only after they have developed, so most doctors will not prescribe them until a bacterial infection is confirmed. However, antibiotics are sometimes used to prevent recurrent sinus and ear infections. They cannot prevent complications of a viral infection.

Bacterial or Viral?

Bacterial Infections:

  • May follow a viral infection that does not improve.
  • Usually localized at a single point in the body: sinuses, ear, lungs.
  • Typical bacterial infections: strep throat, ear infection.
  • Antibiotics do help.

Viral Infections:

  • Usually involve different parts of the body: sore throat, runny nose, headaches, muscle aches. In the abdominal area, viruses cause nausea and/or diarrhea.
  • Typical viral infections: cold, flu, stomach flu.
  • Antibiotics do not help.