Outreach
The One Earth Series. Chapter IV. The Need for a Symbiotic Relationship. Photograph by A. Bravo and M. Espinosa
22 May 2024
The One Earth Series. Chapter IV. The Need for a Symbiotic Relationship
The One Earth Series
Alicia Bravo and Manuel Espinosa. Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC). Ramiro de Maeztu, 9. 28040 Madrid, Spain.
This series comprises four Chapters devoted to describing the One Earth concept. We shall discuss the relationships between two separate, albeit intimate, beings sharing the same niches in many cases: Humans and Bacteria. Why are we afraid of Bacteria? Will Bacteria kill us all? How can we defend ourselves from their deadly attacks? Must we share the same niches? These and many other questions will be raised and discussed here. But we can anticipate the answer: We must share and co-exist. Else, Humans will be doomed.
Introduction
We finished our previous Chapter with a question about the increase in deadly bacterial infections: Is there any turning back to previous situations? We offered a tentative answer: perhaps yes. The immediate next questions would be: Why maybe only? Are we not ready to fight the superbugs? The answer to this latter question is no, we are not prepared. Recent numbers estimate that nosocomial infections (hospital-acquired infections) in Spain have a toll of 18 deaths per day, fourfold more than deaths by accidents on the roads. There is still a need for public awareness of the misuse of antibiotics. As usual in our everyday life, we are all too busy with immediate things to solve and pay little attention to health matters… until they affect us directly. Today we may seem gloomy, but we must face the truth. Let us ask you some questions related to your health: Did you learn anything from the COVID-19 pandemic? Have you changed any of your habits? If your answer is yes, then we might have some hope.
What Can We Do?
We have to stop for a while and to think. Then, we can ask ourselves and our politicians: are we doing something? Infections by superbugs are a problem that we all must be aware of and we have to request a proactive attitude against the selection of superbugs. Indeed, we cannot continue with the same ignorance and indifference towards Public Health. Consideration of antibiotics as war-like objects to fight bacterial infections has not benefitted our health nor our understanding of the bacterial world. Under the One Earth umbrella, we could reinterpret the selection of superbugs as the direct result of the overuse of antibiotics. Thus, the selection of superbugs has been due to human intervention derived from biomedical, veterinary, and crop concerns and economic reasons. The lack of interest from the social and political points of view has led to the image of bacterial communities as places where there is a continuous battle to win scarce resources and, eventually, to infect us, humans.
The Bacterial Points of View
As explained in previous Chapters, bacteria live in very different niches and usually do so by forming biofilms. Biofilms can be viewed as communities in which bacteria defend themselves from other competitors or predators, like bacteriophages, other bacteria, and even fungi. Bacteria forming the biofilms secrete various slimy polymers that constitute a scaffold to which they adhere. In the biofilms, bacteria are densely packed and normally share many of the secreted substances that facilitate the obtention of environmental nutrients. Nevertheless, this sharing permits the appearance of ‘cheaters’, bacteria that benefit from the resources of others without contributing to the community's nutrition. Bacteria within the biofilm communicate with each other by synthesizing and secreting chemical signals termed “quorum sensors” to which they have proper receptors. Quorum sensors can be used to ‘count’ how many individuals of the same species are around. When many unrelated species mix in biofilms (polybacterial biofilms), conflicts between bacterial species instead of collaboration can occur. Nonetheless, it has been found that some bacterial species have receptors for quorum sensors secreted by other species, thus being used to ‘spy’ on these other species and, eventually, cooperate with them in the use of nutrients. It seems that our idea of the bacterial world as being in a continuous struggle might not be completely correct and that the behaviors of bacterial communities are far more complex than previously envisaged.
The Point of View of Science
From the above discussion, we are induced to modify our “fighting” views towards bacteria and to ask our representatives to invest more in research and development on infectious diseases and to focus not only on new antibiotics but also on discovering new targets and strategies. To this aim, Artificial Intelligence (AI) approaches are providing new hope to Science. Then, we need an ambitious re-design of the present policies because many countries are being left behind due to economic interests, wars, draughts, and global climatic changes. Infectious diseases are responsible for approximately 25% of deaths globally and these numbers seem to be increasing at least in countries with poor incomes. We must demand to our scientists and policymakers the implementation of strategies to tackle the problem of dealing with superbugs. Then, the scientific point of view should consider global solutions concerning the microbiome as a whole and these solutions must consider, at least, the following steps: i) conservation; ii) restoration, and iii) biofilm (polybacterial communities) management.
Are There Alternatives?
We must implement alternative strategies to deal with bacterial infections. We must design novel antibiotics, there is no doubt, and a new antibiotic to tackle some infections by superbugs has been recently launched. But we must change our attitudes and behaviors surrounding their use, thus avoiding following the same road as before: antibiotic treatment leads to the selection of resistant bacteria, etc. Moreover, alternative strategies can be used alone or combined with novel drugs to treat bacterial infections. Below we mention some alternatives (there might be others, of course):
1) To develop rapid and accurate methods for detecting superbugs, which could be immediately transferred to primary health attention. Of course, fast antibiotic resistance testing is of the essence. That is to say, early detection of superbug-caused infections is the most important step.
2) To develop novel drugs. Combining deep learning techniques with AI has permitted an immense step forward in the computer-aided prediction of structures of proteins. These tools have flourished enormously in the last two years, and now it is possible to design novel antibacterials targeting the essential functions of pathogenic bacteria.
3) To find compounds able to inhibit the transfer of genes among bacteria (horizontal gene transfer). Through this transfer, many bacteria acquire genes that confer resistance to antibiotics. Different natural products have been tested and they are, at present, being used in different laboratories, but at a small scale.
4) To employ bacteriophages (viruses that infect bacteria) able to infect and kill only particular pathogenic bacteria. This approach may be fruitful in the case of some more specific infections.
5) Faecal transplantation from healthy to sick people, which is a method that has been used successfully in the treatment of particular gut bacterial infections.
6) Last but not least, our preferred strategy to cope with bacterial infections is to design drugs that specifically reduce the virulence of pathogenic bacteria. This is a targeted approach that would not affect the rest of the harmless bacterial populations. The antivirulence therapies do not inhibit bacterial growth but diminish the synthesis and/or activity of particular virulence factors.
Final Thoughts
We are confronting the irreversible change in the climate of our Planet Earth. And it will be from our attitude toward this problem that we may or may not succeed. The two photographs below illustrate our concerns and we are not exaggerating. The beauty of the Garajonay National Park (La Gomera) contrasts sharply with the panorama left by the drought in Barcelona in the winter of 2024, one more consequence of human activity. January 2024 (when the lower picture was taken) was the hottest January on record ever, according to the Copernicus Climate Change Service.
Thus, our final thoughts are devoted to:
- Comprehend the bacterial world and its interactions with other living beings.
- Understand how bacterial populations behave and communicate in the different complex niches they inhabit.
- Understand the relationships between the human species and its microbiomes, so that we can globally influence our environment (Lennon et al., 2023).
- Remember that climate change is altering microbial communities in ways that threaten the natural resources of our Planet Earth. Even more, microorganisms are sensitive to the effects of climate change and this may favour the emergence of new infectious diseases. These are some of the considerations that have led to requiring the presence of Microbiologists at international conferences and meetings on climate change (Gewin, 2023).
Further Readings:
In Spanish:
In English:
https://www.dw.com/en/spain-catalonia-declares-drought-emergency-for-barcelona/a-68143732
Lennon, J.T., Frost, S.D.W., Nguyen, N.K., Peralta, A.L., Place, A.R. and Treseder, K.K. (2023) Microbiology and Climate Change: a Transdisciplinary Imperative. mBio 14: e03335-03322.
Gewin, V. (2023) Microbiology must be represented at climate change talks. Nat. Microbiol. 8: 2238-2241.
Acknowledgments
This series attempts to communicate our research at the Centro de Investigaciones Biológicas Margarita Salas, CSIC, and is part of the Grant I+D+i PID2019-104553RB-C21, funded by MICIU/AEI/10.13039/501100011033. Thanks are due to María del Carmen Fernández and Mónica Fontenla for their help during the elaboration of this series.
Other chapters:
Chapter I: link.
Chapter II: link.
Chapter III: link.