Weekly Dose: penicillin, the mould that saves millions of lives

Weekly Dose: penicillin, the mould that saves millions of lives

In developed countries, infectious diseases accounted for most deaths until very recently. And in developing countries, infectious diseases remain the cause of death for a large percentage of the population.

It is in this setting that the discovery of penicillin in 1928 by Alexander Fleming was so instrumental in shaping modern health care. For the first time we had a reliable weapon against common infections; this was the start of the antibiotic era.


By 1942, strains of Staphylococcus aureus were already resistant to penicillin. Today, around the world, many of the bacteria originally sensitive to the effects of penicillin are resistant.

On the other hand, many common bacteria still retain sensitivity to penicillin. Penicillin remains the antibiotic of choice for pneumonia in the community, as common bacteria such as pneumococcus are still overwhelmingly sensitive to penicillin.


And, like all antibiotics, penicillins can lead to infection with Clostridium difficile, an organism that causes severe diarrhoea, due to alteration of the normal gut bacteria.

Penicillins are generally safe to use with other medications. Occasionally, though, they can modify levels of certain medications such as methotrexate, which is used to treat cancer and autoimmune disorders.

Sergio Diez Alvarez, Director Of Medicine, The Maitland and Kurri Kurri Hospital, University of Newcastle, Australia, briefly outlines the discovery of penicillin, how it works, its chemical structure, bacterial resistance development, use and cost and side effects: theconversation.com/weekly-...


9 Replies

  • Penicillin is, in my opinion, VERY over prescribed…

    I write as someone who is still experiencing the after effects of penicillin after over ten years.

    Penicillin totally wiped out all the good bacteria in my gut, destroying the microbiome.

    My digestion system has suffered greatly and no probiotics or other treatment has resolved the problems.

    I would urge anyone who was prescribed penicillin to ask their doctor for a gentler antibiotic treatment to try FIRST before going the penicillin route.


  • I've been on daily penicillin for the last two years since splenectomy. So far it hasn't been too bad with only mild gut issues that weren't there before.

  • Sorry to hear about the problems you had with Penicillin, Dick. Like Mijoed, I have been on daily penicillin since I had a splenectomy a year ago. As far as I can see, it isn't causing any problems- at least not yet. If anything, my gut has been more settled than it used to be. (I take one 250mg capsule twice a day).

    I hope you find some answers for your digestive problems...


  • Hi Paula, thanks for your reply.

    I think this all depends upon the dose. A prophylactic dose may be manageable for many, but I was issued with a large dose to overcome a significant and painful infection. This certainly killed all the infecting bacteria until I could get to London and see a specialist, but at the same time it destroyed my gut bacteria or biome.

    My fault perhaps for living at that time in a place with a primitive healthcare facility, but we cannot always live next to a major hospital.!


  • I agree Kwenda - the dose will make a lot of difference. And different people have different reactions to these things. Has any doctor suggested some sort of "poo capsules" to restore your gut bacteria? I'm not sure how much these are actually being used though...


  • The ‘poo capsules’ are used I understand for Clostridium difficile and after all my penicillin I am only left with what the doctors all call IBS, Irritable Bowel Syndrome. IBS appearing to be a ‘catch-all’ description for anything that the doctors cannot fully analyse.

    By being careful with what I eat I can keep the situation under control, and it does seem that in the last year that the situation is getting better.

    The doctors at first suggested probiotics and have tested some, but without any significant improvement, so I asked about eating blue mould cheeses and was told that as long as my neutrophils were a good number to try this, as well as unpasteurised Real Ale beers.

    Presently I am working on the Real Ale beers, and funnily enough when first attempted they were a disaster but now I am seeing a big improvement. Seriously..!!

    I thus conclude that the penicillin destroyed all my gut biome, and that I have to very slowly rebuild the complete gut biome by eating and drinking a variety of items. The gut biome must presumably be an accumulation of bacteria built up over many decades, so it will take some time to be rebuilt.

    An example of this would be that I lived for many years in a tropical climate and thus was used to the bacteria found in the water and the restaurant foods. But when friends flew in for a vacation they could have a stomach upset or ‘ Montezuma’s Revenge ‘. Clearly they were not used to the local water or foods; their gut biome was different and their gut rebelled.

    Similarly the local mosquitoes were no problem, they would bite but not leave a mark, but on the tourists the mosquitoes could produce large welts. We were used to the mosquitoes and had the necessary resistance now built in..


  • Yes, I too have only heard of "poo capsules" being used for C.Difficile infections.

    But I believe they work by introducing "normal, balanced" gut bacteria from a healthy donor to rebalance people's "out of balance" gut bacterial systems. So I wondered whether they could also be used with other gut problems - especially where the "normal" balance of bacteria in the gut has been upset - which might be the case for some folk with Irritable Bowel syndrome. (Although I realise that IBS can just be a "catch-all" for bowel problems that the doctors cannot fully define)

    It was just a thought, that maybe more research has been done on the "poo capsules" to expand their usefulness in that way.

    But it's good to hear that you're finding some improvement, Dick, with eating blue mould cheeses and Real Ale beers... A much more tasty way of dealing with the problem.. :-)


  • Beer and cheese as a medicine. Yes! Do you think they'd be available on prescription ? 😀 Do you think wine and chocolate may also work Dick?😀

  • If a small wine and some chocolate make you feel better then I would say go for it...

    In moderation of course..!!