Ok this post is really just an excuse to include the cutest picture of all time. But there is a serious reason why the photo came my way.
Brush-tail rock wallabies are endangered in NSW, and considered “near endangered” nationally, so there is a breeding program to save them. The program has succeeded partly by fostering out joeys to tamar wallabies so the mothers can get round to breeding more often, which is pretty cute in itself I’d say.
However, a study by Dr Michelle Power at Macquarie University found that 48% of faecal samples from the captive-bred wallabies contain antibiotic resistant bacteria. It’s zero percent for wild wallabies. We don’t quite know how the wallabies picked up these bugs, but clearly being too close to humans or livestock is not great for them.
In the direct sense this is not a serious problem. These wallabies will soon be hoping wild (indeed some already are). Perhaps if a wild wallaby gets injured in a bushfire and is lucky enough to be rescued a resistance to antibiotics could be an issue, but for most of them it is hardly going to matter. Indeed, it may well be that once the selection pressure of regular exposure to antibiotics is removed the resistance will prove a drag on the survival prospects of the gut bacteria and will slowly disappear.
Nevertheless, it is a testimony to the dangers of overuse of antibiotics that these animals, which have never been directly exposed to these drugs, have acquired resistant bacteria. This probably occurred through the regular swapping of genes that occurs between bacteria. There’s a danger this could continue in the wild, to the point where one day a human gets infected with a zoonotic species that has acquired resistance in the wild along with some particularly deadly characteristics, making it very hard to treat.
Power says there is probably nothing we can do to prevent this happening, other than use antibiotics more wisely – which we should be doing for lots of other reasons. However, she does think this is something worth monitoring. It’s not a reason to stop the captive breeding program since we don’t know if the bacteria will even transfer to the wild animals, and if they do the chances of harm appear to be minimal.