Liz46 I think, if you're taking strong antibiotics, they will cancel out any potential benefits from drinking kefir or eating other 'live' fermented foods. The friendly gut bacteria in those foods are as susceptible to antibiotics as are the pathogenic ones. Every time we take a course of antibiotics, it does our gut flora a lot of harm. It's probably impossible to build up the good bacteria until you finish the course of antibiotics. Then you need to eat plenty of fibre in the form of leafy greens (some raw) and pulses e.g. chick peas, beans and lentils. The raw veg have naturally occurring lactobacilli (the good guys) so go easy on the washing! I don't wash the cabbage I use to make sauerkraut. I just remove any damaged outer leaves.
Anyone fancying giving kefir a try, make sure it's not been pasteurised. There's no benefit to your gut if the friendly bacteria are dead! It's easy to make your own and it'll be live. Lakeland are doing a milk kefir kit lately but you can buy the milk or water kefir grains on Amazon. Lakeland also sell this book:
Fermented Foods for Vitality and Health by Dunja Gulin