I have only ever been required to take antibiotics for diverticulosis on one particularly bad episode & that was Amoxicillin. I got complacent with aggravating foods, nuts & small seeds are a big no no for me & I paid for it with raging temp, intense stomach pain, diahorrea and non stop vomiting. I was close to being hospitalised but thankfully after a liquid diet and antibiotics I was on the mend. I have had other flare ups but have managed to avert the need for antibiotics....but thats me. i avoid doctors like the plague unless its absolutley necessary which is not always a good thing.
My only worry I have for post bypass is avoiding constipation which can also aggravate things. I have had no flares since I have changed my eating habits though. Drinking loads and weetabix or all bran keeps me moving. Fybrogel is another but I don't use this as a rule.
Hope this helps
France's x