Just as a point of interest, I was at one time prescribed prolonged, repeated courses of the antibiotic Trimethoprim for recurrent UTI's by my GP (in fact, it turned out I had interstitial cystitis)! The GP in question just kept lobbing course after course at me without sending samples for lab testing, going on symptoms alone.
After 1 tablet from yet another repeat prescription, I had a biphasic episode of anaphylaxis which very nearly cost me my life. I had NEVER had an allergy to anything before in my life. This then caused a 'cascade' effect in my body and I ended up being treated at a specialist Anaphylaxis Clinic for nearly 2 years, and now react to multiple unrelated medications.
As you may realise, antibiotics are the number 1 cause of medication induced anaphylaxis, and in all cases the individual has to have been exposed to the drug previously for this to happen. I now have to walk a tightrope if ever I need antibiotics again from any class due to my diverse reactions following my initial anaphylaxis, as we just don't know what may trigger another episode. My list of drugs I must avoid is getting increasingly longer - for instance, I can now no longer have morphine and my last surgery was difficult to manage as I had to have pain relief in the form of bolus injections of Fentanyl instead. This was all caused by my GP's gung ho attitude to antibiotics, and it's been nothing short of devastating!