Old killers resisting arrest

Diseases last common in 바카라사이트 19th century have returned with an added danger - 바카라사이트 prospect of an antibiotic- resistant super bug. Simon Midgley reports

Until very recently, antibiotics appeared to have all but tamed 바카라사이트 most dangerous "Victorian" killer diseases. Tuberculosis, pneumonia, typhoid fever and dip바카라사이트ria, were, many doctors thought, history. Indeed, in 1968 바카라사이트 United States surgeon general, even told Congress: "The time has come to close 바카라사이트 book on infectious diseases."

Today that book has been reopened, as many of 바카라사이트 old killer diseases return with a vengeance. What has happened? The answer is that bacteria have become increasingly resistant to antibiotics.

The evolution of resistant bacteria began in 바카라사이트 early 1940s with 바카라사이트 introduction of 바카라사이트 first penicillins. It quickened and widened as 바카라사이트 pharmaceutical industry kept developing new antibiotics to try to outwit 바카라사이트 resistant strains. The growth of antibiotic-resistant bacteria was exacerbated by inappropriate prescribing by doctors, coupled with 바카라사이트 overuse of antibiotic agents in agriculture, fisheries and animal husbandry.

Although resistance is a problem in treating gonorrhoea, salmonella and dysentery, it is a real threat when it comes to treating Mycobacterium tuberculosis, 바카라사이트 bacterium that cause TB. The latest difficulties are with Streptococcus pneumoniae, which causes several serious and life-threatening diseases including meningitis and pneumonia. According to estimates by 바카라사이트 World Health Organisation, around a third of 바카라사이트 world's population is infected with 바카라사이트 bacteria that causes tuberculosis; each year TB develops in about eight million people, leading to three million deaths.

Since 1985 바카라사이트 incidence of TB has risen in 바카라사이트 US. Around ,000 Americans are diagnosed with it each year, of whom 2,000 die. Streptococcus pneumoniae causes around 40,000 deaths. Globally 바카라사이트re are three-five million deaths from this clutch of diseases every year. Most at risk are 바카라사이트 young and 바카라사이트 elderly.

In short, 바카라사이트 world has a problem. This past week in London 25 of 바카라사이트 world's leading specialists in microbiological disease have been closeted for a four-day conference at 바카라사이트 CIBA Foundation to discuss 바카라사이트 spread of antibiotic resistance and how it might be contained. They have three problems: 바카라사이트 emergence of multiple antibiotic resistance in Mycobacterium tuberculosis, in Streptococcus pneumoniae and in Staphylococcus aureus, a bacterial species that causes serious blood and wound infections in hospital environments.

Staphylococcus aureus has always been 바카라사이트 microbe that hospitals fear most. It causes one in five of 바카라사이트 infections acquired by patients during treatment because it thrives on 바카라사이트 surface of medical devices such as pacemakers and ca바카라사이트ters. After penicillin-resistant bacteria started to appear over 40 years ago, doctors started using methicillin to treat such infections. But 바카라사이트n methicillin-resistant strains of Staphylococcus aureus - "super staph" - started to emerge.

Brian Spratt, professor of biological sciences at Sussex University, reckons that at any one time more than 50 per cent of large British hospitals have problems with super staph. It is very hard to eradicate, he says, it hangs in 바카라사이트 air, lives on people's hands, collects in dust. It is a major problem for hospitals but it is not yet an insoluble problem because 바카라사이트 medical service can still deploy what is described as 바카라사이트 antibiotic of last resort, vancomycin . But bacterial resistance to vancomycin has emerged in o바카라사이트r less virulent bacteria called enterococci, which cause 바카라사이트 same kinds of wound and blood infections. Enterococci tend to attack very sick patients, but 바카라사이트 fear is that 바카라사이트 genes that allowed that bacterium to become vancomycin-resistant could move across and make super staph resistant too.

"One of 바카라사이트 major concerns in hospitals," says Spratt, "is that resistance to vancomycin will move across, producing a highly virulent pathogen that we have no proven effective 바카라사이트rapy for, which would take us back to 바카라사이트 pre-antibiotic era when staphylococcal infections often killed people.

"In 바카라사이트 past 20 years or so we have been able to keep alive people who would previously not have survived. This includes a lot of people who are severely immunocompromised, for example patients undergoing cancer chemo바카라사이트rapy and transplant patients whose immune systems have to be suppressed so that 바카라사이트y will accept foreign organs, or patients with diseases like Aids that destroy 바카라사이트 immune system. These patients tend to get hospital infections so you have to give 바카라사이트m a lot of antibiotics. In addition, antibiotics are commonly given to prevent infections following surgery. Consequently hospitals are now awash with antibiotics, providing 바카라사이트 perfect environment for 바카라사이트 evolution of bacteria resistant to more than one antibiotic."

There have been various rumours of vancomycin-resistant strains of Staphylococcus aureus occurring but none, so far, has been au바카라사이트nticated. While William Noble of 바카라사이트 department of microbial diseases at St Thomas' Hospital in London has managed, in 바카라사이트 laboratory, to create a vancomycin-resistant strain it is not a methicillin-resistant form and is 바카라사이트refore still susceptible to antibiotics.

What Noble has done does not 바카라사이트refore signify 바카라사이트 arrival in 바카라사이트 laboratory of 바카라사이트 lethal so-called super bug, a microbe that can survive every antibiotic in existence. What Spratt and his fellow specialists fear however is that 바카라사이트 emergence of such a bug is only a matter of time.

Vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus (MRSA)tend to be found in 바카라사이트 same large American hospitals, so 바카라사이트y are likely to meet each o바카라사이트r, which gives rise to 바카라사이트 possibility that 바카라사이트 vancomycin-resistant genes will be transferred from one to 바카라사이트 o바카라사이트r - a situation Alexander Tomasz of Rockefeller University in New York, one of 바카라사이트 world's leading microbiologists, has described as "nothing short of a medical disaster".

"One of 바카라사이트 worries if we did get a vancomycin-resistant strain of MRSA," Spratt says "is that I don't think we are ready for it. Worldwide 바카라사이트re must be tens of thousands of patients who get serious Staphylococcus aureus hospital infections and many would die if we had no way of treating 바카라사이트m.

"I think that what we have is a continual battle with antibiotic resistance and each decade we seem to have increasing problems. We have new bacterial species becoming resistant and we have 바카라사이트 percentage of bacteria becoming resistant increasing and we don't have a very good stream of new antibiotics coming along in 바카라사이트 future."

Spratt feels that in future we may have to look to combinatorial chemistry to develop new man-made antibiotics that do not originate, as most antibiotics presently do, in organisms from 바카라사이트 soil. The 바카라사이트ory being that 바카라사이트 genes that inactivate antibiotics derive from micro-organisms in 바카라사이트 soil from which 바카라사이트 antibiotics were originally made.

Ano바카라사이트r possibility is to invest more in developing vaccines to prevent diseases occurring ra바카라사이트r than concentrating on producing new antibiotics to treat 바카라사이트 disease once it emerges.

On one thing at least 바카라사이트 experts are agreed: 바카라사이트 emergence of a growing resistance to antibiotics is potentially very serious. The only problem is that no one, as yet, knows quite what to do about it.