Super-bugs arrive.

• Author: Bright, Chris
• Position: Environmental Intelligence - Evolution of microorganisms to develop strains that are resistant to antibiotics

Human pathogens are growing increasingly immune to the drugs used to treat them, a development that threatens the enormous gains made in fighting infectious disease since the introduction of the first antibiotic, penicillin, in 1943. Cheap, safe, and - at first - incredibly effective, antibiotics once seemed to offer the possibility of liberating humanity from some of its deadliest scourges. But today, antibiotic resistance has been discovered in well over 20 different kinds of bacteria, the type of microorganism that antibiotics are used to treat. Some bacterial pathogens, such as the tuberculosis bacillus, have evolved strains resistant to every available antibiotic - more than 100 drugs in all. Widespread resistance is complicating the treatment of nonbacterial pathogens as well, like the HIV virus and the parasite that causes malaria.

The full extent of the problem is not known, since no nation has a satisfactory means of monitoring the spread of resistance, according to the Institute of Medicine, a branch of the U.S. National Academy of Sciences. But a growing body of evidence suggests that resistance is already a major medical burden. In the United States, for example, it is estimated that drug-resistant bacteria now cause about 70 percent of the 90,000 fatal hospital infections that occur every year. The total cost of drug-resistant infection in the United States is now thought to exceed $30 billion. Resistance may be a more noticeable threat in the industrialized world, where it is causing a resurgence of diseases that had been largely suppressed. But with many diseases, the effects will likely be far worse in poorer countries.

One of the most threatening developments involves tuberculosis, the respiratory disease that infects 7.3 million people every year, and kills 2.9 million. One-sixth of all known strains of TB now show some degree of resistance, and resistant strains of the disease occur all over the world. But the problem is at its worst in Russia, where extremely severe forms of multidrug-resistant TB - called "MDR-TB" - have broken out in recent years. Of the 109,000 new cases of tuberculosis that Russia sees every year, an estimated 7 percent are MDR-TB. In Russian prisons, which are a principal breeding ground for the disease, MDR-TB may now account for as many as 20 percent of all new cases. Some 3.5 million Russians may contract MDR-TB by the close of the year 2000, and public health officials regard its spread elsewhere as inevitable. Last year an international panel of physicians who toured Siberian prisons and hospitals called for $100 million in emergency international aid to control the incipient epidemic. According to the visiting physicians, MDR-TB now constitutes "a direct, global public health threat."

Malaria is also showing increased resistance. Malaria is caused by a blood parasite, which is present in 300 to 500 million people and kills 1.5 to 2.7 million of them every year. Some 90 percent of all malaria infections occur in Africa, as do 90 percent of all malaria deaths. But for reasons that remain obscure, the center for malaria resistance is in western Thailand, along the border with Myanmar. It was in this area in the 1950s that doctors began to encounter resistance to quinine, the first effective and widely available malaria drug. This was also the area where quinine's successor, chloroquine, was first defeated. (Malaria in most parts of the world is now resistant to both drugs.) The standard malaria drug today is mefloquine, but by 1996 infections in western Thailand were showing a 50 percent resistance to that drug too. Among infected children, the rate was running at...