Used against Gram-positive (. Streptococcus , Staphylococcus ), Gram-negative (. Brucella , Salmonella , Haemophilus ) and obligate anaerobic bacteria (. Clostridium , Bacteroides fragilis ). Other sensitive organisms include Chlamydophila , Mycoplasma (unreliable in treatment of ocular mycoplasmosis) and Rickettsia . Resistant organisms include Nocardia and Mycobacterium . Acquired resistance may occur in Enterobacteriaceae. 
Regrettably there is no equivalent product which can be bought without prescription. Your cat is probably allergic to flea bites and so the occasional bite is causing a dramatic itching effect. This will actually settle down if you treat for fleas thoroughly, diligently and for long enough. Getting rid of all the fleas is actually not an easy task and it takes some while for all the flea eggs lost in nooks and crannies around the home to hatch out and develop. If you have treated the house extremely well then this will be dramatically reduced, but you will not get every one. Almost certainly the occasional flea will make it onto your cat and manage to bite before being killed off by the flea treatment you should be regularly using on your cat. Eventually you will succeed in getting the flea population to such a low level that they are not a problem for your cat and then the skin will settle down. Then you will never see any fleas, though the occasional one may be present at times. This takes some time and so you must continue to treat your cat for fleas, while making sure you treat the house very well. It is possible, but not as easy as most people expect, which is why this sort of skin problem occurs and tends to persist.