Hello everyone- just finished my morning clinic, and I'm here and happy to answer questions about antimicrobial resistance. I am part of a national group (infectious diseases and medical microbiology specialists and pharmacy colleagues) that are interested in helping to control the spread of resistance through prudent antibiotic use (AMMI Canada Antimicrobial Stewardship and Resistance Committee.) I told my group I may call on them as "lifelines" if we get really in depth questions!
Let's start with a broad question, which I think most of us can relate to:
What are the ways we commonly misuse or overuse antibiotics?
The most common by far is when antibiotics are used for viral infections - the issue is that the diagnosis can be hard to be certain of, and "it MIGHT be bacterial" - both the doc and patient want the patient to feel better. The issue of antibiotics as "societal" drugs- with overuse/inappropriate use causing resistance- is a lot more distant when you have a miserable, achy, stuffed up patient looking to their doctor to help them feel better. Another issue is using broad spectrum drugs when simpler ones ought to work as well. Outside the scope of this, concerns in agricultural-veterinary antibiotic use impact our resistance ecology as well.
We have a question from a reader on that last point:
I believe long term-low dose antibiotic use for growth promotion is more frequent in poultry and swine production- I am not personallly aware that the numbers are tracked, as it doesnt require vet prescription and may be imported without being tracked.
There is evidence - whether it is "strong" is somewhat subjective! The type of studies I have seen range from case studies looking at carriage of resistant pathogens in a farm family and the farm employees, and their livestock-to impact of restriction of antibiotics for growth promotion in swine on a country wide basis and downstream effects. I am NOT a agr-vet resistance expert, though- I see people! Thus, I would be more up to date on human literature. I can look for a review I have somewhere on my hard drive, and post more info on that point as we move through questions however.
Let's turn to humans, then. We have a couple of questions related to use of antibiotics in humans.
That does cause concern for people- if they have chronic lung infections, or bone infection or other conditions that require frequent or prolonged antibiotics, they worry that they will become "resistant", or that it will be damaging to their healthy bacterial flora. However, if you need antibiotic therapy for a significant bacterial infection, there is no "too much" defined, as the risk of taking them is theoretical compared to the risk of a true progressive bacterial illness. We do know, for example, that a common used class of antibiotic- quinolones- can impact an individual's carriage of resistant bacteria for 3-6 months after taking it. The majority of people who receive antibiotics for good reason do not have any identified complications related to them. Rash (maybe 1/1000), C.difficile colitis (up to 25% but likely lower) are individual risks.
Therein lies the challenge! Even as an Infectious Diseases specialist, I commonly have difficulty deciding on whether an infection like sinusitis or a sore throat is bacterial or viral: fact is, however, that MOST of both are viral. Lab testing (throat swabs, white blood cell count differentials) can help but may not be available right away.
Because people generally wait 2-4 days to see their doc, they may be at peak misery when seen, and if it's viral, DUE to get better anyway.
- to finish up my last question.....
Therefore, it may be a good idea to get tests and wait it out longer, with red flags identified to know to start a prescription - increased fever, worsening sinus pain and tooth tenderness in spite of decongestants and sinus rinses, ot call to fill when throat swab is available. The "Watch and Wait" is likely the most practical approach.
It is a theoretic risk- a precutionary stance would be that as laboratory based data have shown possible resistance developing in bacteria like E.coli and Salmonella- it may co-select for resistance, or it might also just encourage resistant strains to predominate. Having said that, this lab bench based work hasnt been SHOWN to be impacting human health much at the moment. I would say, though, that infection prevention using plain soap and water is highly effective so triclosan doesnt add much but this theoretic concern, and may be more of a marketing hook than anything else. Antibacterial soaps don't really have a practical role.
Interesting question. Tackling from a few different angles: Fascinatingly, bacteria carried antibacterial resistance genes before we were around. We didn’t invent antibiotics, we discovered them … genetic analysis suggests that microbes invented beta lactam antibiotics and beta lactamase enzymes to resist those antibiotics > 2 billion years ago. In many cases, though, it takes cell resources to express resistance so the bacteria don't SHOW resistance unless exposed to the antibiotic.
SO....Before penicillin became available, a common bad bug, Staphylococcus aureus, was 100% sensitive to it. Resistance rose over the first 10 years of penicillin use very quickly- now Staph aureus is basically close to 100% resistant over about 50 years. In other examples, E.coli used to be close to 100% sensitive to ciprofloxacin, now shows about 20-40% resistance in about 20 years.
So what happens to people who get those infections you mentioned? How do doctors treat resistant diseases?
Please note: that's PENICILLIN resistance in Staph aureus, now we use cloxacillin, drugs called cephalosporins, or Vancomycin for the highly resistant MRSA, which is unfortunately on the rise as an infection causing organism. So, the plan usually is to change to an antibiotic that works by a different mechanism, to which the bacteria tests susceptible. Complicated patients who have a lot of antibiotic exposures and hospital admissions can harbour highly resistant bacteria that can be VERY hard to treat with the current menu of antibiotics, and the rate of new antibiotic development has dropped a lot, so that remains a concern. The usual worst case scenario is having to use a whatever we have to - possibly a more complicated or toxic antibiotic regimen- in cases where there is resistance.
Thanks, everyone, for reading and submitting great questions. Sorry we couldn't get to all of them.
Dr. Saxinger, any last thoughts before we end?
Thanks for the invitation, again, and nice corresponding with you all!