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11 February, 2020 11:36:24 AM


Use of antibiotics

Antibiotic-resistant superbugs are on the rise and we’re being urged to forgo antibiotics wherever possible to limit their spread
Mohammed Abul Kalam, PhD
Use of antibiotics

Antibiotics aren't a one-size-fits-all treatment – the one we had last time might not work on the infection we have at the moment. So how do doctors determine which one is likely to work?In the days before antibiotics, deaths from bacterial infections were common.

Seemingly minor illnesses could escalate in severity, becoming deadly in a matter of hours or days. These days, antibiotics can be life-savers. In the community, they’re commonly used to treat bacterial infections of the lung, urinary tract, eye, throat, skin, and gut.
But they’re not needed for all bacterial infections – many infections will resolve on their own without treatment. And of course, antibiotics don’t treat viral infections such as colds and flu, or fungal infections such as tinea or thrush.
Antibiotic-resistant superbugs are on the rise and we’re being urged to forgo antibiotics wherever possible to limit their spread. But serious bacterial infections can only be dealt with effectively using these drugs.So when should we take antibiotics? The easy answer, of course, is when our doctor tells us to. But there’s more to it.
We know that rates of bacterial resistance track antibiotic usage rates. So, as a community, the more we take these drugs, the more likely we are to have superbugs down the line. In general, a patient will be given antibiotics if symptoms are severe (a high fever or skin rash, for instance, or inflammation spreading around an infection site); we have a higher risk of complications (such as an elderly patient with suspected pneumonia); or if the infection is persistent.

Getting it right: To prescribe, the doctor makes an educated guess as to what may be causing the infection. This is based on knowledge of what type of bacteria are normally found in these cases and, if available, the patient’s history. But she doesn’t know exactly what type of bug is causing the infection. In the absence of an accurate diagnosis, as well as to minimize potential risk to the patient, a broad-spectrum antibiotic is used to “cover as many bases” as possible.

Until we can develop point-of-care technology that can identify a bug on demand, such broad-spectrum drugs (the grenade approach to bacteria) are a better option for doctors than targeted specific drugs (a sniper against superbugs). But the latter is the better long-term option for the patient and the community, although it may not always work.

One key problem with broad-spectrum “grenade” antibiotics is that they can cause collateral damage by killing a lot of good bacteria. We now know that we have about a kilogram and a half of good bacteria in our guts that help us digest food. They also “crowd out” potential nasty infections caused by bad bacteria.

There are cases where patients on antibiotics end up with diarrhea, thrush (a vaginal infection caused by Candida that goes wild when protective bacteria are wiped out), or nasty infections, such as Clostridium difficile, that can lead to severe colitis.

And it gets worse: a recent Danish study that followed more than a million patients found an association between frequency of antibiotic use and Type II diabetes, generating considerable media interest. It found people who received more than four courses of the drugs over 15 years were 53% more likely to develop diabetes.Of course, there’s the cause-effect corollary. People who were already heading towards the disease may simply have been less healthy, more prone to infection, and hence had more visits to the doctor to get antibiotics. The study showed an association between antibiotics and diabetes, not causality.

So where do we stand now? Remember bacterial infections can kill, and antibiotics save lives, so if you’re really feeling crook, go to your doctor and take her advice. But also think twice. If we have a bad cold or think we have the flu, remember this may be due to a viral infection. And using antibiotics could do you more harm than good in the longer term.

The real game-changer in all of this will be a “tricorder” diagnostic that can identify a bug on site. With such a technology, a doctor could prescribe the right drug, the first time, in time. So be sensible about using antibiotics and let’s keep our eyes on this prize.

Even when antibiotics are necessary, they’re not a one-size-fits-all treatment: not all antibiotics kill all types of bacteria.

What type of bacteria is causing the infection?If our doctor suspects we have a serious bacterial infection, they will often take urine or blood test, or a swab to send to the pathologist. At the lab, these tests aim to detect and identify the bacteria causing the infection. Some methods only need to detect bacterial DNA. These DNA-based approaches are called “genotypic methods” and are quick and highly sensitive. Other methods involve attempting to culture and isolate bacteria from the sample. This can take one to four days.

What antibiotic can fight the infection?If antibiotic treatment is necessary, the isolated bacteria can be used in the second series of tests to help determine the right antibiotic for your infection. These are called antimicrobial susceptibility tests.

Like the tests that first detected the bacterium causing your infection, they can be done using DNA-based (genotypic) methods or by culturing the bacterium in the presence of various antibiotics and assessing what happens (phenotypic methods).

Genotypic tests tend to identify which antibiotics won’t work so they can be ruled out as treatment options; ruling out the ones that won’t work leaves the ones that should work.For phenotypic tests, the bacterium is regrown in the presence of a range of antibiotics to see which one stops its growth. A range of concentrations of each antibiotic is often used in these tests.

Selecting the right antibiotic (if we need one at all): Antibiotics are only useful for treating infections caused by bacteria, not viruses or fungi. Hopefully, the doctor has correctly assessed our illness as likely due to infection caused by bacteria, and that the type of bacterial infection we have is one that benefits from treatment with antibiotics. Some don’t. Its unlikely antibiotics will be of benefit for infections such as uncomplicated, acute otitis media, (a middle ear infection) in people older than two, or acute bacterial rhinosinusitis. And also, not every antibiotic works for every infection. There arebroad-spectrum antibiotics that work against a wide range of bacterial types. Narrow spectrum antibiotics are only effective against some bacteria. For instance, the older penicillins are used to treat infections caused by the gram-positive bacterium Streptococcus pneumonia and have much less effect on other bacteria.

Even if an antibiotic was once effective against a specific bacterium, it may no longer be, as the bacteria may have become resistant to that antibiotic. For example, gonorrhea used to be reliably treated with a single type of antibiotic. Now, because of antimicrobial resistance, the recommendation is for therapy with two types of antibiotics. Bacterial resistance to antibiotics, or antimicrobial resistance, is a significant and growing problem.

So how does the doctor select the “right” antibiotic for you? In a perfect world, antibiotic treatment choices are carefully constructed from a combination of information about the patient, the nature of the infection, the species of bacteria causing the infection and the confirmed activity of the selected antibiotic against that bacterial species.

So, in the event I do have a bacterial infection, were prescribed the “right” antibiotics and have started taking them – when will wefeel better?

The goal of antibiotic treatment is to get rid of the illness-causing bacteria. Antibiotics either kill bacteria (bactericidal) or stop them from multiplying, without necessarily killing them (bacteriostatic). Either way, antibiotics begin to act from the moment you start taking them, stopping or slowing the bacteria from dividing.

Some bacteria may be less affected than others and may take longer to be adversely affected by the antibiotic. Bacteria such as Pseudomonas aeruginosa cause infections that are notoriously difficult to treat and these infections may be slow to respond to antibiotic treatment even if the most appropriate antibiotic is used. Each of the bacteria causing our illness contributes to our feeling unwell. The fewer remaining, the better you are going to start to feel.But feeling unwell is not just down to the bacteria. Our body responds to infection by mounting an immune response. This may be directed at the infecting bacteria, to any of our own tissue that has been damaged by the infection, or both, all of which leave we feeling generally unwell. So, while antibiotics attack the underlying cause of the infection, there are other things going on too.

Even once the antibiotics have started work on the bacteria, our body has to tidy up the aftermath of the infection. Our immune system mops up the damage and debris that occurred during the infection. That includes the broken bits of damaged or dead bacteria and similarly, any fragments of our own damaged tissue.

While our immune system is starting to take over responsibility for clearing up, our body also needs to repair the damage done during the infection by the bacteria or our immune system. The overall effect is that we may feel tired and generally unwell for some time even though the antibiotics have begun to work and the infection is resolving.

Feeling worse?More important, perhaps, than when we’ll start feeling better, is what to do if we begin to feel worse. Depending on the severity of our infection, if we are feeling worse after one to two days of taking antibiotics, or less time if we have to worryabout new symptoms, we should go back to our doctor. Preferably it should be the one we saw the first time.

The information available to the doctor from our two visits, combined with any lab test results that may have come through, will assist in deciding whether the first diagnosis was correct if we’re on the right antibiotic or need a different one or any antibiotic at all.

Why it’s important to get the right antibiotic: Naturally, we want to receive an antibiotic that will effectively treat our infection. But what’s wrong with taking an antibiotic that does the job too well or, conversely, is ineffective?

Antibiotics that are too strong will not only clear our infection but will also kill other good bacteria, disrupting our microbiome and possibly causing other knock-on effects. On the other hand, an ineffective antibiotic will not only fail to treat the infection adequately, but it can also still cause side effects and disrupt our microbiome.

A broader consideration for the judicious use of antibiotics is that overuse, or ineffective use, contributes unnecessarily to the development of antibiotic resistance. All antibiotic use promotes resistance in other bacteria they come in contact with, so minimizing and optimizing their targeted use is important. The right antibiotic choice for our infection is a complex decision that must often be made before key additional evidence to support the decision is available. As test results become available, the treatment antibiotics may be refined, changed or even stopped.

The writer is Former Head, Department of Medical Sociology, Institute of Epidemiology, Disease Control & Research (IEDCR),  Dhaka, Bangladesh


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Editor : M. Shamsur Rahman
Published by the Editor on behalf of Independent Publications Limited at Media Printers, 446/H, Tejgaon I/A, Dhaka-1215.
Editorial, News & Commercial Offices : Beximco Media Complex, 149-150 Tejgaon I/A, Dhaka-1208, Bangladesh. GPO Box No. 934, Dhaka-1000.

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