[Street Pharmacist]

I figured I could start a discussion on health topics for everyone as it's my area of passion and there's obviously big things happening with regards to public/private finances, health promotion, vaccines, etc.

My biggest passion is antibiotic resistance, so I figured it’d be a good place to start. This is mainly because I feel as a pharmacist, it's one of the issues most in my control. Here are some basics.

There are many mechanisms that make antibiotics work. For example, they can interfere with cell wall formation rendering bacteria porous which leads to cell death (penicillin), it can also interfere with DNA copying, protein synthesis (Biaxin), and others. Antibiotic resistance develops when bacteria have been subjected to antibiotics either repeatedly, or at sub-therapeutic levels. They then evolve resistance mechanisms due to mutation and natural selection. These mutated genes that code for resistance mechanisms can then be shared between different species of bacteria through a variety of different ways (eg. Plasmids, bacteria having sex). This basically means that just because a type of bacteria has not shown resistance and maybe has not had experience with a type of antibiotic, resistance can still be found in a specimen. These bacteria that evolve to develop resistance mechanisms (eg, developing an enzyme that destroys penicillins, changing the binding site for the drug rendering it useless, etc) then propagate that ability. Resistance is simply evolution. Even in a perfect world where all antibiotics were used appropriately, resistance would develop, albeit slowly. We can, however, modify the course of resistance and buy time until technology can catch up.

There are now many bacteria that have multiple resistance mechanisms (MRSA – Methicillin Resistant Staph. Aureus). In fact, we now actually have drugs that are not sensitive to anything (eg. Some tuberculosis strains, VRSA). Obviously, this is a big concern as it means we may be headed back to an era without antibiotics to save us from simple infections. Already, people are dying in developed nations due to infections that we have no ability to treat properly. Though this is less of a problem here in Canada, it is likely going to get worse. The causes of the growing resistance are many – simple evolution, overuse of antibiotics, inappropriate use of antibiotics, widespread agricultural use, improper disposal of antibiotics, and overuse of "anti-bacterial" washes.

Currently there are many studies looking at better ways to prevent infection (methylene blue+ultraviolet light before surgeries, pre-surgical cleaning procedures, ozonated water,etc). Unfortunately, nothing widely used yet.

Virtually no new antibiotics have been developed in the last decade. Worse still, none are in the pipeline either. This means as more resistance is forming, we have no new weapons to fight them. Resistance to one drug usually means any drug using the same mechanism will likely also be ineffective. This leads to many drugs becoming ineffective as most of the antibiotics we have are in the same classes. For example cloxacillin, amoxicillin and penicillin all have the same mechanism, so if a bacteria it's resistant to one, it likely will be resistant to all.

Many antibiotics are used in feed for livestock to PREVENT infection as it increases overall weight in the herd due to less illness. I do not know the Canadian numbers, but I assume they would be the same as in the US where between 50-70% of all antibiotics consumed are for livestock, almost exclusively added to feed. In fact, the only oral antibiotic we have to treat a really nasty human bug called Pseudomonas aeruginosa is Ciprofloxacin, and 80% of all produced is used in feed. If we lose that drug for Pseudomonas, only IV antibiotics will work. Some sub-species (?) of bacteria found in chickens are now 100% resistant to Cipro (this means 100% of the samples found of this sub-species were found to be resistant). Obviously, this means they can transfer these mutations to human pathogens.

Antibacterial soaps are the devil. Studies have shown that traditional antibacterial soaps are no more effective at preventing infection, and increase resistance rates. Our society is becoming increasing germophobic and ironically, this extreme fear of bacteria may be leading to the development of more pathogens.

In areas where antibiotics are available for self selection, macrolide resistance in some respiratory pathogens is above 90%. Not only does this mean that these bugs can share and make things worse here, but these people can travel and bring these bugs here too.

Some antibiotics breed resistance due to their pharmacokinetics (they way the drug is absorbed, distributed and eliminated in the body). For example, azithromycin has such a long elimination half-life, that sub-therapeutic doses are seen in the body for days after the last dose is taken. Some studies have shown resistance found in almost 50% of S. pneumonia isolates taken 3 months after therapy.

By far though, the most modifiable part of this growing problem, is prescribing; especially in respiratory illness. For those not familiar with respiratory infections, they are mostly either viral or bacterial. Bacteria are treated with antibiotics. Viruses on the other hand, are not alive and cannot be treated by antibiotics.

Many studies have shown the scope of this issue. In my health region, IHA, 70% of patients who received a diagnosis of acute bronchitis received antibiotics. Acute bronchitis is virtually never bacterial, so antibiotics should never be prescribed. Pharyngitis (sore throat) is mostly viral; bacterial "strep throat" can only be diagnosed with a swab. Despite this, many patients received antibiotics and no swab. Acute sinusitis is not often bacterial either (depending on the study, bacterial sinusitis is between 0.5 and 15% of cases), and antibiotics are not recommended. Despite this, the majority of patients received antibiotics. The problem goes beyond simply over prescribing though, as proper selection, duration and dosing are also often improper.

Now, before we blame the doctors, we should look at the patients. In a survey, 80% of patients felt if their respiratory illness was "bad enough" they should get antibiotics. The kicker was that 80% of those who felt that way said they would see another doctor if they didn't get antibiotics. Another exasperating factor is time. With the current fee-for-service model, doctors really are limited in their ability to spend the time explaining this to the patient. Liability concerns are bound to influence prescribing habits as well. The fact that the problem is so large suggests that the pressure is an issue.

What can you do? Ask your doctor if you truly need antibiotics when they are prescribed. Obviously, your doctor will know better than you, so don't argue the point, but explain that you do not expect antibiotics. Understand that severity of illness does not increase the chance you need antibiotics.

Thoughts?