It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Sunday, June 02, 2024
Brain damage reveals part of the brain necessary for helping others
UNIVERSITY OF BIRMINGHAM
Our willingness to help others is governed by a specific brain region pinpointed by researchers in a study of patients with brain damage to that region.
Learning about where in the brain ‘helping’ decisions are made is important for understanding how people might be motivated to tackle large global challenges, such as climate change, infectious disease and international conflict. It is also essential for finding new approaches to treating disorders of social interactions.
The study, published in Nature Human Behaviour, was carried out by researchers at the University of Birmingham and the University of Oxford, and shows for the first time how a region called the ventromedial prefrontal cortex (vmPFC) has a critical role in helping, or ‘prosocial’ behaviours.
Lead author Professor Patricia Lockwood said: “Prosocial behaviours are essential for addressing global challenges. Yet helping others is often effortful and humans are averse to effort. Understanding how effortful helping decisions are processed in the brain is extremely important.”
In the study, the researchers focused on the vmPFC, a region located right at the front of the brain, which is known to be important for decision-making and other executive functions. Previous studies using magnetic resonance imaging (MRI scanning) have linked the vmPFC to choices that involve a trade-off between the rewards available and the effort required to obtain rewards. However, these techniques cannot show whether a part of the brain is essential for these functions.
Three groups of participants were recruited for the study. 25 patients had vmPFC damage, 15 patients had damage elsewhere in the brain, and 40 people were healthy age and gender-matched control participants. These groups allowed the researchers to test the impact of damage to vmPFC specifically.
Each participant attended an experiment where they met another person anonymously. They then completed a decision-making task that measured how willing they were to exert physical effort (squeezing a grip force device) to earn rewards (bonus money) for themselves and for the other person.
By enabling participants to meet – but not see – the person they were ‘working’ for in advance, researchers were able to convey the sense that participants’ efforts would have real consequences, but hide any information about the other person that could affect decision-making.
Each choice the participants made varied in how much bonus money for them or the other person was available, and how much force they would have to exert to obtain the reward. This allowed the researchers to measure the impact of reward and effort separately, and to use advanced mathematical modelling to precisely quantify people’s motivation.
The results of the study clearly showed that the vmPFC was necessary for motivation to help others. Patients with vmPFC damage were less willing to choose to help others, exerted less force on even after they did decide to help, and earned less money to help others compared to the control groups.
In a further step, the researchers used a technique called lesion symptom mapping which enabled them to identify even more specific subregions of the vmPFC where damage made people particularly antisocial and unwilling to exert effort for the other person. Surprisingly, damage to a nearby but different subregion made people relatively more willing to help.
Co-lead author Dr Jo Cutler said: “As well as better understanding prosocial motivation, this study could also help us to develop new treatments for clinical disorders such as psychopathy, where understanding the underlying neural mechanisms can give us new insights into how to treat these conditions.”
“This region of the brain is particularly interesting because we know that it undergoes late development in teenagers, and also changes as we get older,” added Professor Lockwood. “It will be really interesting to see whether this area of the brain can also be influenced by education – can we learn to be better at helping others?”
Human ventromedial prefrontal cortex is necessary for prosocial motivation
ARTICLE PUBLICATION DATE
27-May-2024
AFRIKA
Cultural and linguistic networks of Central African hunter-gatherers have ancient origin
Evolutionary anthropology
UNIVERSITY OF ZURICH
IMAGE:
BAYAKA HUNTER-GATHERERS IN CONGO PLAYING MUSICAL INSTRUMENTS AND DANCING, WHICH HELPS THEM TO SPREAD CULTURAL TRAITS AND SPECIALIZED VOCABULARY BETWEEN DIFFERENT GROUPS.
Central Africa has been occupied by hunter-gatherer populations for hundreds of thousands of years, according to recent research based on genetic, archaeological and paleoenvironmental data. However, contemporary hunter-gatherers living in the Congo Basin speak languages that they have acquired from their agricultural neighbors, the Bantu, in recent times. This raises the question which elements of ancient cultural diversity in Central Africa stem from long-term evolution and regional cultural exchange predating agriculture, and which aspects are influenced by interactions with farming communities.
Culture, language and genes co-evolve
An international team of researchers led by Andrea Migliano from the Department of Evolutionary Anthropology at the University of Zurich (UZH) has discovered previously unknown links between culture, language and genes among different hunter-gatherer populations in Central Africa. “We found that the distribution of musical instruments among hunter-gatherers correlates very strongly with those genetic segments that are of ancient origin. So, these populations were exchanging musical instruments long before there were any agricultural populations in the region,” says Migliano.
The project was developed by Cecilia Padilla-Iglesias, PhD student and first author. The timing of genetic exchanges between populations can be inferred by tracing the origins of specific genome segments. To this end, the researchers assembled genetic data from eleven Central African hunter-gatherer groups and divided their DNA into segments based on the timing of the exchanges: those introduced through introgression or exchange with Bantu populations, those from recent exchanges between hunter-gatherer populations, and those of ancient origin.
Additionally, the team compiled an extensive dataset of musical instruments and foraging tools, along with their names from historical documents and ethnographies. They then compared how the structure of cultural diversity – the similarity between groups in musical instrument and subsistence tool repertoires, based on the presence or absence of similar musical instruments – correlated with genetic diversity at different points in time.
Extensive social networks spanning thousands of kilometers
“It was surprising that, although the different Central African hunter-gatherer groups speak languages from very different families, they share a disproportionate number of words related to music. Therefore, these words can be traced back to a time before the hunter-gatherer populations adopted the languages of their Bantu neighbors,” says anthropologist Andrea Migliano.
The results suggest that extensive interactions among hunter-gatherer groups in the Congo Basin, even those separated by thousands of kilometers, influenced not only their genetic makeup but also their linguistic and cultural traits. These extensive social networks helped maintain a cultural diversity that evolved thousands of years before the arrival of the agriculture in the region. Migliano adds: “The large-scale cultural networking of modern humans has deep roots in the past, at least in Central Africa.”
Deep history of cultural and linguistic evolution among Central African hunter-gatherers
ARTICLE PUBLICATION DATE
27-May-2024
Biobased building materials less sustainable than concrete in South Africa, experts find
UNIVERSITY OF BRISTOL
Scientists at the University of Bristol have discovered that mycelium composites, biobased materials made from fungi and agricultural residues, can have a greater environmental impact than conventional fossil-fuel-based materials due to the high amount of electricity involved in their production.
In the findings, published today in Scientific Reports, the team show that this is further exacerbated in countries like South Africa where fossil fuel is the main source of electricity. This isn’t helped by mycelium composites’ shorter lifespan and the need for multiple replacements over the duration of long-term applications, thereby increasing their overall environmental impact.
Despite this discovery, they also concluded that the overall potential damage on the environment caused by this technology can be mitigated by incorporating alternative energy sources like firewood.
Lead author Stefania Akromah explained: “Mycelium composites are considered a sustainable alternative to traditional fossil fuel derived materials.
“However, the sustainability of these materials depends on various location-specific factors like resource availability, economic structures, cultural practices, and regulations.
“Our main focus was to determine if producing mycelium composites is sustainable in Africa and to identify which manufacturing processes have the most potential to damage the environment.”
Now team plans to evaluate the environmental impact of mycelium composite technology under various scenarios aimed at reducing the overall footprint, to conduct uncertainty analysis to verify the accuracy of the current results, and to compare the footprint of mycelium composites with other emerging green materials that are or could be used in Africa. Additionally, they are also looking to investigate the economic feasibility and social implications of the technology to provide a comprehensive evaluation of its sustainability.
Stefania continued: “Africa faces heightened vulnerability to climate change impacts owing to its limited financial resources, making it crucial to mitigate these impacts as much as possible.
“This study offers valuable insights that can be used to proactively address the potential impact of this technology on the environment and human health.
“It was interesting to find that even a technology that is generally perceived as sustainable can sometimes have a greater environmental impact than conventional fossil-fuel-based materials. This highlights the importance of life cycle assessment studies and the need to carefully consider all factors, including energy sources and lifespan, when evaluating new materials.”
“Stefania’s work just demonstrates that it’s important, when conducting LCAs, that geographical considerations, and cultural practices, are taken into account, to calculate sustainability. The right decisions can then be made to ensure that manufacturing has as low an impact as possible, while also contributing to local economies and African livelihoods.”, said Professor Steve Eichhorn, Director of the Centre for Doctoral Training in Composites, Science and Manufacturing (CoSEM) – from which this study was funded.
The research was conducted using a life cycle assessment (LCA) methodology following the ISO 14040 and 14044 standards for evaluating the environmental impact of materials or processes.
‘Potential Environmental Impact of Mycelium Composites on African Communities’ by Stefania Akromah, Neha Chandarana, Jemma L. Rowlandson and Stephen J. Eichhorn in Scientific Reports.
JOURNAL
Scientific Reports
METHOD OF RESEARCH
Data/statistical analysis
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Potential Environmental Impact of Mycelium Composites on African Communities
Rapid urbanization in Africa transforms local food systems and threatens biodiversity
INTERNATIONAL INSTITUTE FOR APPLIED SYSTEMS ANALYSIS
Since the early 2000s, Africa’s urban population has more than doubled, reaching over 600 million in 2020. If current growth continues, the urban population is expected to double again by 2050. In Africa, the annual rate of urban area expansion has surpassed the rate of urban population growth. Globally, future urban area expansion is expected to cause significant food production losses, reduce biodiversity, and increase land-use change emissions, jeopardizing human livelihoods and the natural environment.
Typically, recent research on the environmental impact of urban expansion treats it as the conversion of various land covers to urban land, focusing only on the direct effects. In a new study, published in Nature Sustainability, IIASA researchers and their colleagues demonstrate the complexity of expected urbanization and its multiple environmental impacts.
“As Africa is urbanizing the fastest, its food system is also transforming rapidly. This puts a lot of pressure on food security in what is already the most food-insecure region in the world,” notes Koen De Vos, study author and a guest research assistant in the Integrated Biospheres Futures Research Group of the IIASA Biodiversity and Natural Resources Program. “In our study, we consider both direct land-use changes and indirect effects, such as agricultural displacement and dietary shifts associated with urbanization, particularly concerning rice consumption.”
The researchers developed a method to integrate all of this information using the GLOBIOM model, creating an elaborate, complex, and multidimensional study that is unprecedented in its scope. Results show that, contrary to common belief, urban area expansion has a limited impact on food production losses, as agricultural land simply expands elsewhere. At the same time, the impact on natural lands is more significant, as it encompasses not only the direct effects of urban area expansion but also the subsequent displacement of agricultural land.
The most important environmental spillover effects arise from dietary changes, particularly rice consumption. As people eat more rice in African cities, more rice needs to be produced, resulting in greater reliance on imports and local production. Consequently, this leads to an increase in methane emissions, additional loss of natural lands, changes in water usage, and biodiversity loss.
“This result adds to the growing evidence that our diets will be one of the major drivers of planetary health,” explains Marta Kozicka, a study coauthor and IIASA researcher in the Integrated Biospheres Futures Research Group.
In their study, the research team highlights that policymakers should adopt holistic approaches in the decision-making process. Integrating indirect land-use effects and dietary shifts into land-use planning and policymaking is essential to tackle future sustainability challenges.
Reference De Vos, K., Janssens, C., Jacobs, L., Campforts, B., Boere, E., Kozicka, M., Leclère, D., Havlík, P., Hemerijckx, L.M., Van Rompaey, A., Maertens, M., Govers, G. (2024) African food systems and biodiversity affected by urbanization via dietary shifts rather than area expansion. Nature Sustainability DOI: 10.1038/s41893-024-01362-2
About IIASA:
The International Institute for Applied Systems Analysis (IIASA) is an international scientific institute that conducts research into the critical issues of global environmental, economic, technological, and social change that we face in the twenty-first century. Our findings provide valuable options to policymakers to shape the future of our changing world. IIASA is independent and funded by prestigious research funding agencies in Africa, the Americas, Asia, and Europe.
African food systems and biodiversity affected by urbanization via dietary shifts rather than area expansion
ARTICLE PUBLICATION DATE
30-May-2024
Three years after its launch, AFROSCREEN meets all its objectives, developing effective genomic surveillance to tackle epidemics in sub-Saharan Africa
INSTITUT PASTEUR
The AFROSCREEN project, financed to the tune of €10 million by Agence Française de Développement (AFD), has been working since 2021 to set up or strengthen sequencing platforms and build an operational network for monitoring emerging pathogens in West and Central Africa and Madagascar. With 25 partners in 13 sub-Saharan African countries, AFROSCREEN will improve the detection, characterization and genomic surveillance of emerging pathogens for epidemic preparedness and response. The AFROSCREEN project, coordinated by ANRS Emerging infectious diseases, an autonomous agency of Inserm, as part of a consortium with Institut Pasteur and Institut de recherche pour le développement (IRD), was launched in July 2021 to respond to the Covid-19 epidemic.
The results are presented at the AFROSCREEN regional symposium on May 29 and 30, 2024 in Dakar, Senegal, in the presence of all scientific, technical and financial partners, as well as CDC Africa and WHO.
Genomic sequencing, a public health tool
Today, genomic sequencing is an essential public health tool for detecting and tracking infectious pathogens with epidemic potential. A better understanding of the genome of pathogens and their genetic evolution can guide the production of diagnostic tests, drugs and vaccines, leading to better control of epidemics at both local and international levels.
The Covid-19 pandemic highlighted the disparities between continents in terms of surveillance and sequencing systems. At the end of October 2021, of the 4.6 million sequences shared on the free and public GISAID tool worldwide, only 49,000 came from the African continent, representing less than 1% of Covid-19 cases diagnosed there.
With this in mind, AFROSCREEN was designed to improve preparedness and response activities at regional level, support decision-makers in defining public health priorities in each partner country, and produce data to feed into the international public health effort.
AFROSCREEN regional symposium: review and prospects of the genomic surveillance network in Africa
On May 29 and 30, 2024, the “AFROSCREEN Regional Symposium: a genomic surveillance network for emerging pathogens” will be held in Dakar, Senegal. The event will bring together partners, CDC Africa and WHO representatives, health authorities from the countries concerned and international funding agencies. The aim of the symposium is to take stock of the project's scientific and technical achievements, and to discuss future prospects for capitalizing on this network.
Three years after its launch, the AFROSCREEN project has made it possible to:
improve the SARS-CoV-2 detection and sequencing capabilities of the 21 laboratories in the network by providing equipment (sequencers, reagents, laboratory materials). Capacity building in these laboratories has contributed to an increase in the number of sequences deposited on GISAID by countries (around 10,000 sequences deposited);
training over 150 people in charge of sequencing, analysis and data sharing, including biologists, technicians, data managers, bioinformaticians and staff in charge of surveillance and epidemiological investigations;
create and run the AFROSCREEN network of partner laboratories, comprising 25 partners in 13 African countries;
set up, reactivate or support 77 sentinel sites in 11 countries for epidemiological surveys and sample collection, as well as for surveillance of SARS-CoV-2 and its variants.
This network can now be rapidly mobilized in the event of the emergence or re-emergence of pathogens with high epidemic potential beyond SARS-CoV-2: influenza, Mpox, dengue, Lassa, chikungunya, Marburg, etc.
The GISAID open-access platform enables the rapid sharing of data (genetic sequences and virus-related clinical and epidemiological data) on influenza and SARS-CoV-2 viruses.
Surprising properties of elastic turbulence discovered
Revealing elastic turbulence has more in common with classical Newtonian turbulence than expected
OKINAWA INSTITUTE OF SCIENCE AND TECHNOLOGY (OIST) GRADUATE UNIVERSITY
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A POLYMER STRETCHING IN THE ELASTIC TURBULENT FLOW. THE POLYMERS IN THE LIQUID ACT LIKE MICRO SPRINGS, GETTING STRETCHED BY THE FLUID MOTION BEFORE GIVING ENERGY BACK TO THE FLUID WHEN CONTRACTING.
Blood, lymph fluid and other biological liquids can have surprising and sometimes troubling properties. Many of these biological solutions are non-Newtonian fluids, a type of liquid that is characterized by a non-linear relationship between stress and strain. Consequently, non-Newtonian fluids don’t necessarily behave as one would expect from a liquid. For example, some of these peculiar fluids deform when touched lightly but will act almost as a solid when a strong force is applied.
And biological solutions are no exception when it comes to unique properties - one of them being elastic turbulence. A term that describes the chaotic fluid motion that results from adding polymers in small concentrations to watery liquids. This type of turbulence exists only in non-Newtonian fluids.
Its counterpart is classical turbulence, occurring in Newtonian fluids, for example in a river when the water at high speed flows past a bridge's pillar. While mathematical theories exist to describe and predict classical turbulence, elastic turbulence yet awaits such tools despite their importance for biological samples and industrial applications. “This phenomenon is important in microfluidics, for example when mixing small volumes of polymeric solutions which can be difficult. “They don’t mix well because of the very smooth flow,” explains Prof. Marco Edoardo Rosti, head of the Complex Fluids and Flows Unit.
So far scientists have thought of elastic turbulence as completely different from classical turbulence, but the Lab’s most recent publication in the journal Nature Communications might change this view. Researchers from OIST worked collaboratively with scientists from TIFR in India and NORDITA in Sweden to reveal that elastic turbulence has more in common with classical Newtonian turbulence than expected.
“Our results show that elastic turbulence has a universal power-law decay of energy and a so far unknown intermittent behavior. These findings allow us to look at the problem of elastic turbulence from a new angle,” explains Prof. Rosti. When describing a flow, scientists often use a velocity field, “we can look at the distribution of velocity fluctuations to make statistical predictions about flow,” says Dr. Rahul K. Singh, the publication’s first author.
When studying classical Newtonian turbulence, researchers measure velocity over the entire flow and use the difference between two points to create a velocity difference field. “Here we measure velocity at three points and compute the second differences. First, a difference is computed by subtracting fluid velocities measured at two different points. We then subtract two such first differences yet again, which gives us the second difference,” explains Dr. Singh.
This type of research came with an additional challenge - running these complex simulations requires the power of advanced supercomputers, “our simulations sometimes run for four months and output a huge amount of data,” says Prof. Rosti. This added level of detail led to a surprising finding - that the velocity field in elastic turbulence is intermittent. To illustrate what intermittency in flow looks like, Dr. Singh uses the electrocardiogram (ECG) as an example.
“In an ECG measurement the signal has small fluctuations interrupted by very sharp peaks. This sudden large burst is called intermittency,” says Dr. Singh. In classical fluids, such fluctuations between small and very large values had already been described but only for turbulence that occurs at high flow speeds. The researchers were surprised to now find the same pattern in elastic turbulence occurring at very small flow speeds, “at these low speeds we did not expect to find such strong fluctuations in the velocity signal,” emphasizes Dr. Singh.
Their findings are not only a big step towards a better understanding of the physics behind low velocity turbulence but also lay the foundations for developing a complete mathematical theory describing elastic turbulence. “With a perfect theory, we could make predictions about the flow and design devices that can alter mixing of liquids. This might be useful when working with biological solutions,” says Prof. Rosti.
Intermittency in the not-so-smooth elastic turbulence
ARTICLE PUBLICATION DATE
27-May-2024
Viper-mimicking snake from Asia is a unique branch in the reptile evolutionary tree
UNIVERSITY OF HELSINKI
IMAGE:
MOCK VIPERS NOT ONLY LOOK LIKE TREE-DWELLING VIPERS BUT ALSO ACT LIKE THEM. INTRIGUINGLY, THEY HAVE A FAKE ‘FANG’ IN THE FRONT OF THEIR MOUTH, WHICH BEFOOLS A PREDATOR INTO THINKING THAT THEY POSSESS VENOM FANGS DURING AN OPEN-MOUTHED THREAT DISPLAY. HOWEVER, THERE IS ALSO AN ACTUAL FANG IN THE BACK OF THE JAW, WHICH CARRIES A WEAK VENOM EFFECTIVE ONLY ON THEIR LIZARD PREY.
The evolutionary history of the mock viper has been solved by an international research team led by scientists from the University of Helsinki. This mildly venomous viper look-alike represents a totally unique branch in the tree of life of snakes.
The evolutionary history of the mock viper, a mildly venomous, widely distributed Asian snake that mimics highly venomous vipers for self-defence, has been solved. The mock viper represents a completely unique branch in the tree of life of snakes, and hence, it has been allocated into its own new family named Psammodynastidae.
This small, feisty snake has long presented a puzzle to evolutionary scientists due to its unresolved evolutionary history. To solve the puzzle, the researchers analysed DNA sequences of over 4500 genes and several dozen high-resolution micro-computed tomographic scans.
“Mock vipers are part of the superfamily Elapoidea, a major group of snakes to which one-fifth of global serpent diversity belongs. Evolutionary diversification within this superfamily happened very rapidly approximately 50 million years ago. Rapid evolutionary diversifications areprobably the most challenging evolutionary scenario for a geneticist or evolutionary biologist to resolve”, says the lead researcher Sunandan Das from the University of Helsinki.
Mock vipers not only look like tree-dwelling vipers but also act like them. Intriguingly, they have a fake ‘fang’ in the front of their mouth, which befools a predator into thinking that they possess venom fangs during an open-mouthed threat display. However, there is also an actual fang in the back of the jaw, which carries a weak venom effective only on their lizard prey. The Elapoidea superfamily has multiple snake families with various types of venom and fangs, for example cobras and mambas.
Another completely new family-level lineage, Micrelapidae, within Elapoidea was discovered in 2023 by Sunandan and Professor Juha Merilä.
“The discovery of a new family of any vertebrate animals is surprisingly rare, an almost once-in-a-century phenomenon. This is a lifetime achievement for an evolutionary biologist. You rarely, if ever, see descriptions of whole new families of well-studied vertebrate animals anymore.’’ says Sunandan.
The inference of the phylogenetic position of mock vipers, along with that of other elapoid snakes, will pave the way for a much better understanding of snake venom fang origin and evolution. Long, unique branches in the phylogeny, like that of mock vipers, contains a high degree of evolutionary distinctiveness, an index used by biologists for prioritising conservation. Hence, reinstating the mock viper or Psammodynastes into its own ‘dynasty’ also serves an important conservation goal.
Researchers have discovered a new distinctive and secretive snake species in the Hejaz region of Saudi Arabia.
Rhynchocalamus hejazicus is a small snake bearing a black collar and reddish colouration, distinguishing it from its closest relatives. A uniformly black ‘melanistic morphotype’ of the species has also been discovered.
The new species is widely distributed and fills much of the existing distribution gap between the Levant and the coastal regions of Yemen and Oman for the genus Rhynchocalamus.
Rhynchocalamus hejazicus inhabits sandy and stony soils with varying vegetation cover and can be found in habitats disturbed by humans, suggesting that the species should not be categorised as threatened according to IUCN criteria.
Little is known about the species’ natural history and behaviour, and further monitoring and conservation efforts are necessary to better understand its ecological dynamics and natural history. However, it appears that Rhynchocalamus hejazicus has mainly nocturnal activity as all individuals were encountered active at night.
"The discovery of a new species of snake widespread in the central-western regions of Saudi Arabia is surprising and gives rise to the hope that more undiscovered species might be present in the Kingdom" the authors say.
Most of the observations of the new species are the result of intense sampling efforts in a vast area around the ancient Arabic oasis city of AlUla, fostered by the Royal Commission for AlUla, Saudi Arabia, which is pushing forward scientific activities and explorations to promote conservation in the region. The intensifying of field studies in Saudi Arabia in the last years is leading to fruitful collaborations and such important findings as this study, to which many experts from multiple teams have contributed significantly.
The discovery of such a distinctive snake highlights the existing gap in the description of rare and secretive species, and the need to enhance sampling efforts and monitoring strategies to fully capture species diversity in unexplored areas.
Original source
Licata F, Pola L, Šmíd J, Ibrahim AA, Liz AV, Santos B, Patkó L, Abdulkareem A, Gonçalves DV, AlShammari AM, Busais S, Egan DM, Ramalho RMO, Smithson J, Brito JC (2024) The missing piece of the puzzle: A new and widespread species of the genus Rhynchocalamus Günther, 1864 (Squamata, Colubridae) from the Arabian Peninsula. Zoosystematics and Evolution 100(2): 691-704. https://doi.org/10.3897/zse.100.123441
Black ‘melanistic morphotype’ of Rhynchocalamus hejazicus pictured in life.
The missing piece of the puzzle: A new and widespread species of the genus Rhynchocalamus Günther, 1864 (Squamata, Colubridae) from the Arabian Peninsula
ARTICLE PUBLICATION DATE
30-May-2024
The effect of combinations of antibiotics and natural products on the antimicrobial resistance of Staphylococcus aureus and Pseudomonas aeruginosa
Natural Products on the Antimicrobial Resistance of Staphylococcus aureus and Pseudomonas aeruginosa
BENTHAM SCIENCE PUBLISHERS
The growing resistance of bacteria to existing antimicrobial drugs is a major problem, making it essential to find new ways to treat bacterial infections. Sometimes, antibiotics alone are not effective enough. To address this, combining different drugs is often used. One approach is to use a combination of antibiotics and plant extracts or phytochemicals. This combination therapy is particularly useful for patients with serious infections caused by drug-resistant pathogens.
Seven antibiotics (gentamicin, ceftazidime, ciprofloxacin, doxycycline, amoxicillin, ceftriaxone, and azithromycin) were obtained from a local pharmacy. Minimum inhibitory concentrations (MIC) were determined using the broth micro-dilution method. Various antimicrobial combinations were tested on 20 multidrug-resistant (MDR) clinical isolates (10 S. aureus and 10 P. aeruginosa). Additionally, the antibacterial activity of several volatile oils (limonene, rosemary, salvia, thyme, and black pepper), plant extracts (moringa seed, curcumin, and capsicum), and phytochemicals (thymol and chitosan) was evaluated against S. aureus and P. aeruginosa using the broth micro-dilution method.
Our results showed that combining ceftriaxone with ciprofloxacin or gentamicin had a strong synergistic effect against S. aureus. Additionally, combining amoxicillin with ceftazidime reduced the MIC by five to six times. For MDR P. aeruginosa isolates, the combination of azithromycin with doxycycline reduced the MIC of azithromycin by about five to six times. The combination of gentamicin with ceftriaxone was also significant. Among natural compounds, thymol, rosemary oil, curcumin, capsicum, and moringa seed extract showed the highest synergistic activity with the tested antibiotics against S. aureus and P. aeruginosa.
In conclusion, the development of new antibiotics is lacking, so improving existing ones is crucial. Our study indicates that combining antibiotics and antibiotics with natural plant compounds are very promising strategies for tackling complex bacterial resistance.
