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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

Bloemfontein's quality of tap water compares very favourably with bottled water

2009-08-04

The quality of the drinking water of five suburbs in Bloemfontein is at least as good as or better than bottled water. This is the result of a standard and chemical bacterial analysis done by the University of the Free State’s (UFS) Centre for Environmental Management in collaboration with the Institute for Groundwater Studies (IGS).

Five samples were taken from tap water sources in the suburbs of Universitas, Brandwag, Bain’s Vlei, Langenhoven Park and Bayswater and 15 samples were taken of different brands of still and unflavoured bottled water. The samples were analysed at the laboratory of the IGS, while the interpretation of the analysis was done by the Centre for Environmental Management.

“We wanted to evaluate the difference in quality for human consumption between tap water and that of the different brands of bottled water,” said Prof. Maitland Seaman, Head of the Centre for Environmental Management.

“With the exception of two samples produced by multinational companies at their plants in South Africa, the different brands of bottled water used for the study were produced by South African companies, including a local small-scale Bloemfontein producer,” said Prof. Seaman.

According to the labels, the sources of the water vary from pure spring water, to partial reverse osmosis (as an aid to standardise salt, i.e. mineral, content), to only reverse osmosis (to remove salts). (Reverse osmosis is a process in which water is forced under pressure through a pipe with minute pores through which water passes but no – or very low concentrations of – salts pass.)

According to Prof. Seaman, the analysis revealed some interesting findings, such as:

• It is generally accepted that drinking water should have an acceptable level of salt content, as the body needs salts. Most mineral contents were relatively higher in the tap water samples than the bottled water samples and were very much within the acceptable range of drinkable water quality. One of the bottled samples, however, had a very low mineral content, as the water was produced by reverse osmosis, as stated on the bottle. While reverse osmosis is used by various producers, most producers use it as an aid, not as a single method to remove nearly all the salts. Drinking only such water over a prolonged period may probably have a negative effect on the human physiology.

• The pH values of the tap water samples (8,12–8,40) were found to be slightly higher (slightly alkaline), like in all south-eastern Free State rivers (from where the water is sourced) than the pH of most of the bottled water samples, most of which are sourced and/or treated in other areas. Two brands of bottled water were found to have relatively low pH levels (both 4,5, i.e. acidic) as indicated on their bottles and as confirmed by the IGS analysis. The health implication of this range of pH is not significant.

• The analysis showed differences in the mineral content given on the labels of most of the water bottles compared to that found by IGS analysis. The possibility of seasonal fluctuation in content, depending on various factors, is expected and most of the bottling companies also indicate this on their labels. What was a rather interesting finding was that two pairs of bottled water brands claimed exactly the same mineral content but appeared under different brand names and were also priced differently. In each case, one of the pair was a well-known house brand, and the other obviously the original producer. In one of these paired cases, the house brand stated that the water was spring water, while the other (identical) “original” brand stated that it was spring water treated by reverse osmosis and oxygen-enriched.

• Nitrate (NO3) levels were uniformly low except in one bottled sample, suggesting a low (non-threatening) level of organic pollution in the source water. Otherwise, none of the water showed any sign of pollution.

• The bacterial analysis confirmed the absence of any traces of coliforms or E.coli in any of the samples, as was also indicated by the bottling companies. This is very reassuring. What is not known is how all these waters were sterilised, which could be anything from irradiation to chlorine or ozone treatment.

• The price of the different brands of bottled water, each containing 500 ml of still water, ranged between R3,99 and R8,99, with R5,03 being the average price. A comparison between the least expensive and the most expensive bottles of water indicated no significant difference in quality. In fact, discrepancies were observed in the most expensive bottle in that the amount of Calcium (Ca) claimed to be present in it was found to be significantly different from what the analysis indicated (29,6 mg/l versus 0,92 mg/l). The alkalinity (CaCO3 mg/l) indicated on the bottle was also found to differ considerably (83 mg/l versus 9,4 mg/l). The concentration of Total Dissolved Salts (TDS) was not given on the product.

“The preference for bottled water as compared to Bloemfontein’s tap water from a qualitative perspective as well as the price discrepancy is unjustifiable. The environmental footprint of bottled water is also large. Sourcing, treating, bottling, packaging and transporting, to mention but a few of the steps involved in the processing of bottled water, entail a huge carbon footprint, as well as a large water footprint, because it also requires water for treating and rinsing to process bottled water,” said Prof. Seaman.

Media Release
Lacea Loader
Deputy Director: Media Liaison
Tel: 051 401 2584
Cell: 083 645 2454
E-mail: loaderl.stg@ufs.ac.za
3 August 2009

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