“How can one distinguish between a viral and a bacterial infection?”
My son keeps getting a mild cold with every changing season. While the doctor keeps saying it is a viral he also prescribes antibiotics. I always thought antibiotics are for bacterial infections only. How can one distinguish between a viral and bacterial infection? Should I see a different doctor?
3 Answers
Viruses vs bacteria. Not only can they cause similar symptoms but many illnesses—like pneumonia, meningitis and diarrhea—can be caused by either
Your doctor a medical history and physical exam. The doctor may order blood or urine tests to decide.
Most doctors consider four things when faced with a virus vs. bacteria question:
Have a fever?
Been sick long?
What color is it? While green or yellow mucus can be a sign of a bacterial infection
What’s your throat look like? White spots can be a sign of bacteria. A sore throat without other cold symptoms can be strep throat, which absolutely requires antibiotics.
Your doctor a medical history and physical exam. The doctor may order blood or urine tests to decide.
Most doctors consider four things when faced with a virus vs. bacteria question:
Have a fever?
Been sick long?
What color is it? While green or yellow mucus can be a sign of a bacterial infection
What’s your throat look like? White spots can be a sign of bacteria. A sore throat without other cold symptoms can be strep throat, which absolutely requires antibiotics.
If your son acquires a "cold" with nearly every change of season, it may be due to neither a bacteria or virus, but rather a seasonal allergy. I would suggest application of an allergy panel to see if your son is reacting to certain pollens and grasses that bloom during change of seasons.
Most colds are due to viruses (>95%) and do not respond at all to antibiotics. Your physician is most likely correct that these are colds are viral in origin, but incorrect to prescribe antibiotics - that treat bacterial infections only. Bacterial infections often have accompanying signs and symptoms that are somewhat more severe than common cold viruses. The only true way to differentiate bacterial infections from viral infections is by culture. It is common for doctors to prescribe antibiotics to their patients presenting with cold symptoms, but it is also incorrect to do so.
Most colds are due to viruses (>95%) and do not respond at all to antibiotics. Your physician is most likely correct that these are colds are viral in origin, but incorrect to prescribe antibiotics - that treat bacterial infections only. Bacterial infections often have accompanying signs and symptoms that are somewhat more severe than common cold viruses. The only true way to differentiate bacterial infections from viral infections is by culture. It is common for doctors to prescribe antibiotics to their patients presenting with cold symptoms, but it is also incorrect to do so.
Maira Jessica Medellin-Peña
Infectious Disease Specialist
I am glad you are seeking more information regarding viral and bacterial upper respiratory infections. For a doctor it should be easy to distinguish between a viral and a bacterial infection and often although they diagnose you with a viral infection they prescribe antibiotics due to the possibility of you acquiring a secondary "bacterial" infection - this happens when your immune system is low as it is fighting the viral infection- I avoid prescribing antibiotics unless I am sure it is a bacterial infection and try to educate people telling them to avoid using medications that lower the low grade fever (between 37.5 and 38 degrees Celsius) during the first 2-3 days (unless you need to use them for pain purpose, we don't want you suffering pain). This helps kill the virus attacking your body as it is our natural defense mechanism. I tell them to go to the doctor if the fever persists longer than 3 days or there is evidence of bacterial infection (yellow-greenish nasal discharge, productive cough with yellow-greenish sputum, etc). We are trying to avoid misuse of antibiotics in order to prevent antibiotic resistance in the future, we want the antibiotics to be able to do their job when we really need them!
