Hello It is very difficult to answer your question , which antibiotics is stronger ? Flucloxacillin is effective against staphylococcal infections resistant to benzylepenicillin . While clarithromycin is a macrolide type antibiotics and effective against susceptible infection, respiratory infections , skin & soft tissue infections , mycobacterium aviumcomples infections etc . But you mentioned that there are patches in the lungs on X RAY . So , what type of patches , either upload the X ray or write down about the kind of patches . But in my opinion for respiratory infection clarithromycin is better than flucloxacillin. However , still I advise consult a physician and thereafter take treatment. Hope this will help you. Good luck.