Losing our resistance
He’s only two years old but Jayden Taaibosch has already been prescribed six courses of antibiotics.
‘He’s generally a healthy child, but he picks up normal ear or chest infections. Doctors usually go the antibiotic route,’ says the toddler’s mother, Nina Taaibosch.
Nina’s experience with her son is a common one not only in South Africa but also in the rest of the world.
‘I trust that the doctors know what they are doing so I give him the drugs,’ she says.
But experts are concerned that the over-prescription of antibiotics will create a strain of infectious bacteria that is resistant to all forms of the drugs.
Bacteria are living cells that are invisible to the naked eye and can only be seen under a microscope. Some of the common bacterial infections include pneumoniae, urinary tract infections, tuberculosis, cholera and typhoid.
Bacteria grow by a process called binary fission which essentially allows a parent cell to divide into 2 daughter cells or progeny. A bacterial population thus doubles with each reproductive cycle which may vary from 20 minutes to days. Each daughter cell is identical to the parent in every aspect including its genetic composition/DNA. The replication of DNA during binary fission is amazingly error-free but about once in every 100 million duplications of a gene (small segment of DNA) a mistake is made and the gene does not function normally. Usually this prevents the bacterial cell from growing. However the mutation is occasionally advantageous and the cell is for example able to grow faster or survive in the presence of an antimicrobial substance. When a bacterial population is exposed to an antibiotic, susceptible organisms are eradicated, while resistant ones persist, passing on their resistance to offspring. This process is called mutation that allows bacteria to adapt.
Currently antimicrobial resistance is one of the greatest challenges in the treatment of infections globally and could result in common diseases, such as tuberculosis that is currently curable, becoming untreatable and deadly.
Professor Hugh McGavock, a specialist at Ireland’s Ulster University, recently highlighted the worrying rise of MRSA (a bacterium that enters the body through open wounds) in British hospitals, as a potential sign of things to come.
He warned that this ‘superbug’ (MRSA) was resistant to almost all antibiotics and that indications are that even Vancomycin ‘ until now the most powerful antibiotic of last resort ‘ was unable to treat it.
In South Africa, a recent surveillance study undertaken in 16 KwaZulu-Natal hospitals isolated 1 270 samples of various bacteria. Nineteen antibiotics were used in the study but only a miniscule three percent of the 1 270 samples were neutralised by the drugs. Up to six percent of the bacteria were resistant to one of the 19 antibiotics but a staggering 91% of the isolated bacteria were multi drug-resistant. This means that a number or even all of the antibiotics were completely ineffective.
Professor Sabiha Essack of the School of Pharmacy and Pharmacology at the University of Durban-Westville says although there are no definite statistics, it is estimated that an average South African child is prescribed antibiotic treatment between two to three times annually. But Professor Essack warns that there are variables that could increase or decrease this estimate. These include living conditions, levels of poverty and whether a child is exposed to childcare or after care settings.
But although over-prescribing by doctors has been identified as one of the contributing factors linked to increased resistance, there is agreement that patients are also to blame.
‘Patients often demand an antibiotic even if the infection is viral and the drugs will make no difference. They also often fail to complete the course,’ says Essack, one of South Africa’s leading researchers on antibiotic resistance.
Antibiotic courses vary from five to seven days for uncomplicated urinary tract and respiratory infections to six months and longer for tuberculosis to ensure that all the bacteria are killed. These periods are determined after extensive clinical research. Failing to complete a course could result in a recurrence or persistence of the infection.
A further cause is the addition of small quantities of antibiotics to animal feed for pigs, sheep, cattle and chicken, which are, in turn, consumed by humans. Professor Essack explains that these antibiotics are added to promote growth and prevent infections in the animals.
‘Antibiotic use in agriculture is legislated in South Africa in terms of the quantities and types allowed, but farmers may be using some antibiotics that are not on the list,’ says Professor Essack.
A study by a group of Professor Essack’s students, although not controlled or rigorous, found resistant bacteria in commercially available chicken, beef and pork.
‘This is why it is so important to cook the meat properly and to not use the same utensils for vegetables that may be served uncooked,’ she said.
With public concern about infection heightened, some businesses have identified a lucrative gap in the market and intruded various anti-bacterial products such as soaps, detergents and other cleaning and healthcare products.
Antibacterials have even been ‘impregnated’ into sponges, cutting boards, carpeting, upholstery and children’s toys.
However, experts at the Alliance for the Prudent Use of Antibiotics (APUA) warn that these antibacterial agents may not be the most appropriate way to stop the spread of infectious diseases.
This is because the ‘good’ bacteria are needed to control and compete with ‘bad’ bacteria. Chemical agents do not discriminate between them and can destroy all microorganisms.
Generally, the best approach to eliminating ‘bad’ bacteria is through good hand washing practices, using non-bactericidal soap and water. Proper hand washing should remove 99,9% of bacteria.
Antibacterial agents should ideally be limited to settings where ‘susceptible populations’ – such as young children, the elderly or those whose health is compromised because of AIDS infection, use of immunosuppressive drugs, illnesses requiring hospitalization or chemotherapy – are found.
Professor Iruka Okeke, an assistant professor of biology at Haverford College in Pennsylvania, is a leading scientist in field of antibiotic resistance in Africa and also an advisor for the Alliance for the Prudent Use of Antibiotics (APUA) for sub-Saharan Africa.
Interviewed in a APUA newsletter, Professor Okeke describes a scene she witnessed in Northern Nigeria and that illustrates the problem of antibiotic resistance on the continent.
‘There was a cholera outbreak in 1995 in northern Nigeria. There had been a drought and people were drinking water from very shallow wells that were contaminated. What made it worse was that this happened during the Muslim Ramadan period. People who were sick chose not to break their fast by taking medicine,’ Professor Okeke wrote.
She said that doctors had been warned that there had been an outbreak of an ‘unknown deadly disease’. Cholera is one of the easiest diseases to diagnose but symptoms are particularly dreadful.
‘This outbreak was misdiagnosed. The first drug of choice in treating cholera is tetracycline. Interestingly, this strain was sensitive to tetracycline, but the prescribers were not treating with tetracycline because they thought it wasn’t cholera. They were treating with a whole range of other antibiotics, to which this cholera strain was resistant,’ she said.
She concluded, ‘thousands of people died needlessly’ because of resistance and because of a lack of expertise in terms of making a proper diagnosis. The effect, she wrote, ‘was devastating’.
The World Health Organisation (WHO) has called for urgent global action to address growing antimicrobial resistance. There is consensus that developing world countries, where infectious diseases are commonplace, will probably experience the brunt of this.
Acknowledging the need to address the problem, South Africa’s drug regulator, the Medicines Control Council, has convened a conference scheduled to take place at the end of this month (October).
Some of the objectives will be to update information around resistance, to establish the extent of knowledge on the subject in the country, to consider the impact on public health, to review the use of antibiotics in food production and to consider the co-ordination of a national programme to address the issue.
Bacteria needs no passport and experts agree that the manner in which manner in which the problem is addressed will depend on the critical decisions and actions of individual countries. Ultimately though, the consequences are likely to be felt worldwide.
E-mail Anso Thom
Author
Free to Share
Related
