Norman Swan: Who would have thought that your local supermarket could be somewhere you'd pick up an antibiotic resistant bug? Given the global nature of our food supply and the use of antibiotics in farm animals to promote growth, transmission of resistance via food could be a major issue. And yet we're not good in Australia at testing the meats we buy.

A study in Melbourne supermarkets wanted to see how hard that could be. The research leader was Lindsay Grayson, Professor of Infectious Diseases at the University of Melbourne and Austin Health. Welcome to the Health Report, Lindsay.

So what evidence do we have internationally that this is an issue?

Lindsay Grayson: Oh, there's quite a lot of evidence. For instance, in Europe there's been some interesting studies showing that the rise of multi-resistant super bugs really in food is linked to patients acquiring this in your gut. Because after all, we are what we eat. And so there have been studies for instance in even Geneva, where 86% of the chicken meat delivered to the University of Geneva Hospital carries super bugs.

So this is a pretty major issue…

Norman Swan: But isn't it cooked out? When you cook it, it goes away?

Lindsay Grayson: That's absolutely true, and that's what that study showed, that if you handle properly…but that also involves for the consumer important public health messages about how to handle meat and other produce in their kitchen, and cleaning of utensils and washing their hands and not using the same chopping boards and so forth. At the moment we're not good at doing that.

Norman Swan: And were these Swiss chickens, or overseas chickens?

Lindsay Grayson: Well no-one's quite sure, but I think the Swiss say they were French chickens, actually.

Norman Swan: (Laughs) They would! Depends which part of Switzerland you're in. So what did you do in this study?

Lindsay Grayson: Well it's interesting that back in 2013 there was a senate inquiry about super bugs and antibiotic resistance. And it came up in that that although we have a testing program for drug residues for imported food, we don't actually test for super bugs—that is, the consequence of leftover antibiotics in meat production. And when we asked…well this seems a bit crazy…

Norman Swan: Well presumably it's not just leftover antibiotics. It's the fact that they've had antibiotics to start with.

Lindsay Grayson: Dead right. And you sort of think well that's kind of crazy, and they said, 'Oh no, we're not allowed to do that because of international trade rules, and you've got to have your own in-house testing program for local produce if you're going to test imports.'

Norman Swan: Ah, so you're being fair to the overseas ones, so that you're testing Australian meat.

Lindsay Grayson: Correct. Yeah, that's right. It's important because a lot of the activities, you know we have tight control and we're monitoring super bugs, but if we're not actually testing our imports, then all of this could become undone. And so to establish that sort of program we need to have testing of local produce.

So we thought, well it would be pretty interesting, and actually set up—this was a medical student project, a couple of very interested medical students, Jade and Josh—and we thought well why don't we…although there's been a lot of discussion, what's the best sample to take: do you sample cow faeces or chicken faeces or whatever…we thought well why don't we just be like a consumer and say well, let's just go who cares, if you're buying it from the supermarket you'd want it to be clean and healthy, why don't we go and test some Australian produce so we know that all the skin and bone-containing chicken and pork must be produced in Australia. You can't import meat that contains bone.

And so we went to 30 supermarkets and butchers shops around the Austin, around the catchment area where our patient population comes from, and bought pork spare ribs and chicken drumsticks and then with the aid of Mary Barton, who's a retired professor of veterinary medicine and knows about the correct culture procedures, went ahead and cultured these meats on two separate occasions—so 30 different sites and in total of 120 specimens, and looked in a very detailed way for whether or not Australian meat, chicken and pork, had super bugs on them.

Norman Swan: And?

Lindsay Grayson: Well, the answer is, in short, that although there are a lot of suspicious bugs there, when you actually look in great detail, as we did, that really Australian chicken and pork is very safe. That's the key take-home message, and we had terrific support in fact from John Bourke, the head of the Victorian Pork Association, and similarly for the chicken producers, because they were keen to prove that their produce was safe. Of course we didn't know whether it was their produce or whatever; we were just buying it from the supermarket.

So the first message was that Australian-produced chicken and pork does seem to be safe.

Norman Swan: So does that mean we're not using antibiotics?

Lindsay Grayson: No, well that was the second really interesting thing, that some people have argued well what's the proof that if we use antibiotics in meat production that that really leads to emergence of resistance. Well interestingly trimethoprim sulfa, which is a common antibiotic used in Australian chicken and pork production, the resistance to that antibiotic was the highest of any of them, so just on 70% of pork and chicken had resistance to this antibiotic. Now fortunately that's not one that we rely on terribly much.

Norman Swan: Unless you've got cystitis.

Lindsay Grayson: Well…yes, that's true. But on the other hand what it did show was there is a link between—or confirms that there's an association at least—between if you use a lot of antibiotics in food production that you're likely to see resistance. And similarly, Australia has very tight restrictions on the use of fluoroquinolones, a very important antibiotic class, and there was no resistance.

Norman Swan: So we're all good, don't need to worry?

Lindsay Grayson: No, I think what this shows is that actually this was a pretty simple procedure and it wouldn't be that hard for us to set up a program to really prove what we hope and think is true, and that is Australian produce is safe. But more important that we should really be starting to test our imports, because I think that that may not be necessarily the same.

Norman Swan: And if you found antibiotic resistant bugs in the imports, what would you do?

Lindsay Grayson: Well, I think you'd then want to say, well why are we importing them? And at the very least it would also perhaps get the consumer to say well wouldn't it be good that we know when we go to the supermarket where this produce came from, which country was it produced in, and we can make a decision as to whether to buy it or not.

Norman Swan: And before you go, Lindsay, just a quick tutorial on how you cook raw meat properly, particularly if it might be infected with salmonella and all that sort of stuff.

Lindsay Grayson: Well the first thing is that when you're handling raw meat you should wash your hands after handling it, and similarly with the utensils before then going and handling your salads, because if there were any bugs there you may transmit it to uncooked foods. The second is you probably should use a different chopping board for your raw meat than when you're using it for salads or other food that you're not going to cook. And finally then of course most standard cooking, whether it's pan fried or any of the usual cooking means, by the time the food is what we would call cooked you've killed those bugs. And that's been also shown to be very effective in overseas studies as well as locally.

Norman Swan: I'll leave you to go and have your dinner, Lindsay.

Lindsay Grayson: Thank you.

Norman Swan: Lindsay Grayson is Professor of Infectious Diseases at the University of Melbourne and Austin Health.