Tetracyclines may increase sensitivity to the sun, so avoid prolonged exposure and wear sunscreen when taking such compounds. Tetracycline Resistant Bacteria Bacteria become resistant to tetracyclines by the transfer of DNA from a resistant cell to another. The inclusion of tetracyclines in animal feed has resulted in increased growth in farm animals. This, plus widespread use to treat human infection, has lead to the spread of tetracycline resistant bacteria and the decreased usefulness of tetracycline. Macrolides Macrolides are a class of drugs that are entirely different from penicillins, but are often used to treat many of the same diseases.
Penicillins work by damaging the cell wall of the bacteria.
In contrast, macrolides inhibit protein synthesis but by a different mechanism than tetracycline. The structural differences in macrolides also make them ideal alternatives to penicillin in patients who have penicillin allergies. Macrolides are often used to treat pneumonia, whooping cough, diphtheria, upper respiratory infections, bronchitis, sinus infections, and many other diseases. To help reduce the side effects, try to take these medications 1 hour before or 2 hours after taking an antacid or drinking milk. This class of antibiotics is only available as IV infusions because they are not well absorbed orally.