Today, we often see advertisements for soaps, cleaning products, bandages, and other such things like brooms and wipes that claim to be antimicrobial or contain an antimicrobial. It immediately reminds me of what a germaphobic society we have become. Like all phobias, this is a fear that has gone too far with not enough information to guide it. But not all germs are bad, and not all antimicrobial products may be doing what you intend them to do.
First of all, what one needs to know is what is “antimicrobial”? It may mean a substance that stops the growth of germs (-static) or one that kills germs (-cidal). Second, antimicrobials may hinder germs by means of chemicals that are often not good for many living beings, including us (bleach, ammonia, alcohol, hydrogen peroxide, etc.). Germs may also be hindered by detergents, which are in most soap, or by more specialized compounds made by nature or humans to specifically target certain germs. Antimicrobials, most often though, refer to these compounds that target specific microbes such as antibiotics, antifungals, antiparasitics and antivirals.
The second thing we ought to know is what is a germ? As a microbiologist, I prefer the term microbe and will substitute it for germ from here on. Microbes are tiny life forms. Usually they are microscopic and cannot be seen by the naked eye unless they aggregate into large colonies. Microbes come in a plethora of forms as varied as the colours of the rainbow that can do many things, good and bad. There is the protist, which includes the algae in your pond. These microbes are responsible for putting just as much oxygen in the atmosphere as all the trees in the world. There are the fungi, which include the yeast that help us make our breads and beers. There are viruses, which include the pesky common cold and other viruses that may yet prove useful in making vaccines. Lastly are the bacteria, which include E. coli, which is necessary in our digestive tract and helps us produce vitamin K but on the flip side can cause enterohemorrhagic (bloody) diarrhoea.
Figure 1: Microbes such as the amoeba (protist), E. coli (bacteria), influenza (virus) and yeast (fungi). The sizes are indicated as micrometers (um), which is 0.0001 of a centimetre. The largest microbe shown being the amoeba and the smallest here is the influenza virus.
So some microbes are extremely beneficial to us while others will annoy or kill us. When should we act against a microbe? It is a difficult question to answer but one logical answer would be only when a microbe may make us sick. This answer, surprisingly, is not universally accepted because some microbes are resistant to some antimicrobials such as antibiotics. So what? Treating them may not always work, and since bacteria and all microbes are everywhere and in mixed populations (no man or microbe is an island, more on this later), one may actually affect a population of microbes that was not intended to be affected or treated. When one employs an inefficacious antibiotic, it has been shown many times that a population treated will select for bacteria resistant to the antibiotic. This is called natural selection and was introduced with much controversy by Charles Darwin. Also, it is very possible for the remaining resistant bacteria to have the capacity to transfer their resistance genes or traits to other types of bacteria! This ability is unique to the microbe world but, if you were to imagine this in people, imagine that there was a gene that allowed you to become stronger and build more muscle. If you had sex with another person, rather than reproducing, this person would become larger and stronger like you. You may have heard about this with the “superbugs” in hospitals, which over time have collected so many resistance genes that they are virtually untreatable with antibiotics. This is scary because this may revert us to a time like that when we as humankind did not have antibiotics available to treat disease.
Figure 2: Bacterial conjugation or the ability of bacteria to transfer traits of resistance to antibiotics, as represented as the small red circle, from one bacterium to another. The bacterium on the left originally has the resistance trait and then transfers the resistance trait of the red circle to the second bacterium on the right allowing for both bacteria to be resistant.
How does one control or stop the impending takeover from the “superbug”? This returns us to the question of when we should act against a microbe. Even this is difficult to answer in the medical community where lives are at stake. In relation to this, this is why you may have heard that if you are prescribed antibiotics you should take them at the prescribed time and until the last pill is gone, even if the symptoms were gone much earlier (I implore you!). This is to maximize the chance of killing all the bacteria and allowing no resistant bacteria to survive. With regards to cleaning and ponds, I think the answer is much easier because it is not a life or death scenario. When household cleaning is involved, one only need remove dirt and grime. Microbes are everywhere and it is impossible for household cleaners to kill all germs and, even if they did, I guarantee you that the microbes will return in a few minutes. In that case, why even worry about whether one should use an antimicrobial? It will not make your house any cleaner and it may only serve to allow resistance to spread amongst the populations of microbes. We will then all be sorry when this resistance finally makes its way into a microbe that will cause us disease.
The same principals apply to ponds, which are part of our environment and contain many sorts of microbes. Actually, most microbes in your pond, when given time, will try to establish an ecosystem which will maintain itself. However, because of the scale of most garden ponds they need help. When you have a small volume of water, even as much as 7500 litres the variables tend to act and react very quickly unlike a large natural pond or lake. For example, a rapid increase or decrease in water temperature that is common in small ponds can cause the ecosystem to become unbalanced. Although this is generally not a real problem in a natural pond as it will right itself over time, in a decorative garden pond it tends to make the pond look unsightly. A spike in the water temperature can cause a bloom of algae that makes your pond look like pea soup. In a small pond it is possible that clear water may not ever be achieved without some help. I am personally in favour of probiotics, which instead of trying to kill a specific microbe will selectively promote the growth of beneficial microbes to control the overall microbe population. Our maintenance programs, designed specifically to each pond we work with, often employ a probiotic program to keep your pond clean and healthy without the use of damaging antimicrobials or chemicals.
In the next instalment → No Microbe is an Island, or the Biofilm.
- Not all germs are bad! Some microbes make as much oxygen as all the trees in the world, some help make bread and beer, while others are essential to our own digestion of food.
- Antimicrobials are specialized to stop the growth or reproduction of microbes, or to kill them. These include the antibiotics, antifungals, antiparasitics and antivirals.
- Germs are small living things called microbes, which exist in many varied forms (protists, mycoses, viruses, bacteria).
- Microbes like bacteria can develop resistance to antibiotics and can spread this resistance to other types of bacteria.
- In household cleaning and with ponds, products advertised to be antimicrobial should not be used. It is just recommended to use probiotics.
- Village Pond and Garden will design an environmentally responsible maintenance program and schedule specifically for you pond.
Amoeba photo: Wikimedia Commons
E. coli photo: Eric Erbe, digital colorization by Christopher Pooley, both of USDA, ARS, EMU. Wikimedia Commons
Influenza photo: Wikimedia Commons
Yeast photo: Frankie Robertson, Wikimedia Commons
Bacterial Conjugation sketch: Magnus Manske, Wikimedia Commons