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Disinfectants – are we at the end of the road?

09 October 2020 | Story Leonie Bolleurs | Photo Supplied

SARS-CoV-2, an enveloped coronavirus, is susceptible to most disinfectants. Therefore, the majority of disinfectants, including those containing 70% ethanol, should be able to kill the virus fairly quickly.

Nevertheless, it was found that some bacteria are highly resistant to several commercially available disinfectants. These bacteria are currently still quite rare, and the work of the Veterinary Biotechnology group at the University of the Free State (UFS) aims to prevent the development of more highly resistant bacteria.

The research group in the Department of Microbial, Biochemical and Food Biotechnology is working on disinfectant resistance. They recently published an article, ‘Molecular basis of bacterial disinfectant resistance’.

Group members include: Prof Robert Bragg, professor in the department; Dr Charlotte Boucher, research associate; Samantha Mc Carlie, master’s student and laboratory manager; master’s students, Twyne Skein and Gunther Staats; honours students, Carlo Visser, Bernadette Belter, Boudine van der Walt, Jacky Huang, and Mart-Louise van Zyl; and an NRF intern, Gloria Kankam.

According to Mc Carlie, the work being done on disinfectant resistance is largely attributable to the major issues currently experienced with antibiotic resistance.

“Antibiotic resistance is becoming one of the biggest life-threatening challenges of our time – even overshadowing the current COVID-19 pandemic – as multidrug-resistant infections are becoming increasingly difficult to treat. Bacterial infections that are present in hospitals and agriculture are becoming unresponsive to many of the antibiotics currently in use, marking the start of a post-antibiotic era.”

It is predicted that by 2050, antimicrobial resistance could lead to as many deaths as cancer causes today and could account for between 10 million and 50 million deaths per year.

Lack of proper biosecurity

Mc Carlie says the resistance to antibiotics is spreading rapidly due to a lack of proper biosecurity measures in the food and agricultural industry as well as in the hospital environment, even if the COVID-19 pandemic has gone a long way towards increasing the awareness of hospital staff to the importance of good biosecurity. Millions of rands are lost every year due to multidrug-resistant infections in the dairy and poultry industries of South Africa, and superbugs are present in almost every major hospital in the country.

“Currently, the best viable protection we have against bacteria is biosecurity and disinfectants. Biosecurity relies heavily on the use of disinfectants to control bacterial growth. This makes it only more troubling that disinfectant resistance is emerging at an alarming rate.”

She believes it is important to understand the mechanisms of resistance in order to combat resistance to disinfectants. “Once the mechanisms are identified, possible solutions can be investigated.”

The research group is currently monitoring disinfectant resistance, looking at which microorganisms are resistant to which disinfectants. They take environmental samples and test the levels of disinfectant resistance to observe the development and spread thereof.

Once they have an understanding of the development of disinfectant resistance, the Veterinary Biotechnology group will be able to make recommendations to hospitals and the agricultural industry on how to prevent the development of these resistant microorganisms.

“As we learn more about these highly resistant isolates, it will direct day-to-day treatment of multidrug-resistant infections and hopefully aid in the fight against antibiotic and disinfectant resistance,” says Mc Carlie.

The dangers of over-prescribing

“Resistance to antimicrobials such as antibiotics and disinfectants is a natural occurrence. We did not invent antibiotics, we discovered them, and so bacterial resistance has been around for as long as antibiotics have – as a survival strategy.”

“However, the widespread use of antimicrobials creates selective pressure for those microorganisms that are resistant to the antimicrobial being used. Over-prescribing and improper use of antibiotics has led to widespread antibiotic resistance. We expect the same trend to be seen with disinfectant resistance in the near future,” says Mc Carlie.

She urges the public to take note that disease-causing microorganisms can become resistant to antibiotics and disinfectants if they are not used correctly. A course of antibiotics should always be taken at the correct time and until the last dose. In the same way, disinfectants should be used at the recommended level and not diluted below that level.

These resistant organisms are causing major issues in the agricultural and medical industries, but this effect has not been seen in households yet. As long as disinfectants are used correctly, most will be able to kill the novel coronavirus.

There is, however, a need to establish tests on the efficacy of the massive number of ‘hand sanitisers’ that are now suddenly available.

According to Prof Bragg, existing disinfectants and hand sanitisers have been specifically tested against SARS-CoV-2 and have been found to be effective. He says the undergraduate students in the department will be evaluating a wide range of different hand sanitisers as part of their practical training.

Mc Carlie adds that the excessive use of poor-quality disinfectants as hand sanitisers can result in bacteria developing resistance to these disinfectants. “It is therefore very important that reliable high-quality disinfectants are used as hand sanitisers during this COVID-19 crisis, otherwise we will be replacing one crisis with a potentially even bigger crisis.”

Mc Carlie believes there is a need to start looking at alternatives to control bacterial growth. “Disinfectants are currently the only viable option, and if these microorganisms become resistant to disinfectants as well, we will have nowhere else to turn,” she says.

News Archive

Studies to reveal correlation between terrain, energy use, and giraffe locomotion

2016-11-18

More than half of giraffes in captivity in Europe are afflicted by lameness. This high prevalence represents an important welfare issue, similar to other large zoo animals.

According to Dr Chris Basu, a veterinarian at the Royal Veterinary College in the UK, giraffes in captivity are often afflicted by overgrown hooves, laminitis and joint problems. Diagnosis and treatment is limited by our understanding of anatomy and function, more specifically the locomotion of these animals. Although the giraffe is such a well-known and iconic animal, relatively little has been studied about their locomotor behaviour.

Dr Basu recently visited South Africa to do fieldwork on the locomotion of giraffes as part of his PhD studies under the mentorship of world-renowned Professor of Evolutionary Biomechanics, Prof John Hutchinson. This project is a joint venture between Dr Basu and Dr Francois Deacon, researcher in the Department of Animal, Wildlife, and Grassland Sciences at the UFS. Dr Deacon is a specialist in giraffe habitat-related research.

Together Prof Hutchinson and Drs Deacon and Basu form a research group, working on studies about giraffe locomotion.

Wild giraffe population decrease by 40% in past decade

“Locomotion is one of the most common animal behaviours and comes with a significant daily energetic cost. Studying locomotion of wild animals aids us in making estimates of this energetic cost. Such estimates are useful in understanding how giraffes fit into ecosystems. Future conservation efforts will be influenced by knowledge of the energy demands in giraffes.

“Understanding aspects of giraffe locomotion also helps us to understand the relationships between anatomy, function and evolution. This is relevant to our basic understanding of the natural world, as well as to conservation and veterinary issues,” said Dr Deacon.

Locomotion study brings strategy for specialist foot care

On face value it seems as if foot disease pathologies are more common in zoo giraffes than in wild giraffes. “However, we need a good sample of data from both populations to prove this assumption,” said Dr Basu.

This phenomenon is not well understood at the moment, but it’s thought that diet, substrate (e.g. concrete, straw, sand and grass) and genetics play a part in foot disease in giraffes. “Understanding how the feet are mechanically loaded during common activities (standing, walking, running) gives our research group ideas of where the highest strains occur, and later how these can be reduced through corrective foot trimming,” said Dr Basu.

Through the studies on giraffe locomotion, the research group plans to devise strategies for corrective foot trimming. At the moment, foot trimming is done with the best evidence available, which is extrapolation from closely related animals such as cattle. “But we know that giraffes’ specialist anatomy will likely demand specialist foot care,” Dr Basu said.

Studying giraffes in smaller versus larger spaces

The research group has begun to study the biomechanics of giraffe walking by looking at the kinematics (the movement) and the kinetics (the forces involved in movement) during walking strides. For this he studied adult giraffes at three zoological parks in the UK.

However, due to the close proximity of fencing and buildings, it is not practical to study fast speeds in a zoo setting.

A setting such as the Willem Pretorius Nature Reserve, near Ventersburg in the Free State, Kwaggafontein Nature Reserve, near Colesberg in the Karoo, and the Woodland Hills Wildlife Estate in Bloemfontein are all ideal for studying crucial aspects such as “faster than walking” speeds and gaits to measure key parameters (such as stride length, step frequency and stride duration). These studies are important to understand how giraffe form and function are adapted to their full range of locomotor behaviours. It also helps to comprehend the limits on athletic capacity in giraffes and how these compare to other animals.

Drones open up unique opportunities for studying giraffes

The increasing availability of unmanned aerial vehicles (UAVs)/drones opens up unique opportunities for studying locomotion in animals like giraffes. Cameras mounted onto remotely controlled UAVs are a straightforward way to obtain high-quality video footage of giraffes while they run at different speeds.

“Using two UAVs, we have collected high definition slow motion video footage of galloping giraffes from three locations in the Free State. We have also collected detailed information about the terrain that the giraffes walked and ran across. From this we have created 3D maps of the ground. These maps will be used to examine the preferred terrain types for giraffes, and to see how different terrains affect their locomotion and energy use,” said Dr Deacon.

“The raw data (videos) will be digitised to obtain the stride parameters and limb angles of the animals. Later this will be combined with anatomical data and an estimation of limb forces to estimate the power output of the limbs and how that changes between different terrains,” said Dr Basu.

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