Superbugs are not going away

Antibiotic resistant "superbugs" in South Africa's hospitals are likely to make headlines in the coming years as the world faces the threat of an end to potent and cost-effective treatments for many infectious diseases. In recent weeks, 10 patients have tested positive for a "superbug" called New Delhi metallo-beta-lactamase (NDM-1) at Life Glynnwood Hospital in Benoni. NDM-1 ultimately contributed to four deaths. NDM-1 is an antibiotic-resistant enzyme produced by a bacterium. It causes those being treated with underlying conditions to become ill.

The head of clinical microbiology and infectious diseases at the National Health Laboratory Service, Prof Adrian Duse, said the discovery of NDM-1 indicated the presence of the superbug was more widespread in SA's hospitals than was previously thought. But NDM-1 was not a threat to the general public and there was no need to panic, he said. Because the Glynnwood hospital has a proactive screening programme, early detection meant the hospital was more likely to find NDM-1 than other healthcare facilities, he added.

The World Health Organisation (WHO) is sufficiently concerned over the trend of increasing antimicrobial resistance of bacteria to devote this year's World Health Day to raising awareness of the issue. WHO director-general Dr Margaret Chan said that in the absence of urgent corrective and protective actions, the world was heading towards a post-antibiotic era, in which many common infections would no longer have a cure and, once again, kill unabated. She said the world was facing the risk of losing all of its "miracle cures". Chan said the trends were clear and ominous and that no action today meant no cure tomorrow. She said that a time of multiple calamities in the world, the loss of essential medicines - cures for many millions of people - could become the next global crisis. Although developing resistance is an evolutionary phenomenon, the trend has been accelerated by humans through the poor use of antibiotic regimens, or their over-use.

Beyond the headlines, drug resistance has dramatically increased the costs of fighting many infectious diseases including tuberculosis (TB) and malaria. Drug resistance has also slowed gains against childhood death rates from dysentery and pneumonia, and threatens to undermine efforts to treat people living with HIV/AIDS. Multi-drug resistant TB, for example, does not respond to the standard six-month treatment with first-line anti-TB drugs and can take two years or more to treat with drugs that are more toxic and much more expensive.

The research pipeline for replacing frontline antibiotics, which are considerably cheaper than second- and third-line treatments, is small. Unlike drugs that treat chronic illnesses, antibiotics have a poor return on investment because they are taken for a short period of time and cure their target disease. A second debate rages on the effect of the widespread use of sub-therapeutic levels of antibiotics as a growth hormone in livestock production.

With about 60 percent of diseases that affect humans coming from animals, many experts are concerned that livestock are a source of new antibiotic resistant strains. Worldwide, 50 percent of antibiotics go to livestock. But Prof Sahiba Essack, dean of health sciences at the University of KwaZulu-Natal, said that while many antibiotics used for livestock were clear
chemical analogues of those used by humans, and misuse of antibiotics contributed to resistance, the level of risk posed to human health was still contentious in scientific circles. New antibiotics for animals are subject to the same delays as new antibiotics for humans, with pharmaceutical companies pursuing new treatments for chronic diseases.

Karl Gernetzky
Business Day, 7 November 2011