新药早前在一项临床试验中，有效消灭了 “超级细菌”抗药性金黄葡萄球菌(MRSA)。研究员表示：“病菌不太可能发展出对新药的抗药性，同时新药已推出治疗皮肤感染的药膏，希望能在5年内研发出可服用或注射的版本。”研究员称：“新药采用与传统药物截然不同的方式去消灭细菌，能够只消灭葡萄球菌，而不伤及其他微生物。新药是从自然界的一种病毒取得灵感的，该病毒将“内溶素”在细菌的细胞表面，透过撕裂细胞外层，成功杀死细菌。”
MRSA bacteria (highlighted in purple) under a scanning electron microscope (Credit: Wikipedia)
Our First Weapon Against Superbug MRSA
An artificial alternative to antibiotics has been developed to fight hospital superbugs such as MRSA. The drug, Staphefekt, is reported to be the first new type of weapon to be added to the medical arsenal against infection in a quarter of a century.
Five out of six patients with MRSA (methicillin-resistant Staphylococcus aureus) skin infections were cured in a small-scale trial at the Public Health Laboratory in Kennemerland, the Netherlands, scientists reported at the Antibiotic Alternatives for the New Millennium conference in London yesterday (5 Nov).
Superbugs kill some 5,000 people a year in Britain and perhaps 25,000 in the United States and the situation is getting worse.The drug, developed by Dutch biotechnology company Micreos, combines two bits of a virus enzyme called an endolysin that rips the microbes apart from the outside.
Antibiotics have to get inside the bugs to do their job, but many of their targets, including gonorrhoea, salmonella, tuberculosis and E coli, have evolved strains with thicker outer membranes that block the medicine.
Staphefekt contains a portion of the endolysin enzyme that latches on to parts the bacterium’s outer skin that are fundamental to the way it works and are therefore unlikely to change.
“It’s a new molecule designed from fragments that already exist in nature,” said Dr Bjorn Herpers, a clinical microbiologist involved in the trial. “The results are exciting, and demonstrate the potential this technology has to revolutionise the way we treat certain bacterial infections.”
The company hopes to have the drug available for patients as a pill or injection within five years. Among its advantages is that it is targeted specifically against Staphylococcus, and will not kill other, benign, bacteria.
“With the introduction of Staphefekt, we enter a new era in the fight against antibiotic resistant bacteria, targeting only the unwanted bacteria,” said Mark Offerhaus, the chief executive of Micreos. “This is a far more logical and elegant approach.”
Existing antibiotics have been losing their potency in recent decades as more and more bacteria mutated into drug-resistant forms.
This has sparked growing global concerns about an “antibiotic apocalypse”, returning us to the days when even a simple scratch could be fatal.
British Prime Minister David Cameron warned last year of a new medical “dark age”.
“We are so desperate for new alternatives and this one looks like it’s at the leading edge,” Brendan Wren of the London School of Hygiene and Tropical Medicine toldThe Times.
Scientists have been working on endolysins for decades and some predict that this will be the first of many new drugs based on the enzymes, each tailored to attack a specific microbe.
In part, this resistance has emerged because doctors have been prescribing the existing drugs for viral infections such as colds, wher they are ineffective.
But it is also because many patients stop taking the drugs when they start to feel better, but before the infection has been wiped out.
The surviving bugs are the ones better equipped genetically to deal with the medicine and over time their descendants can evolve into drug-resistant varieties.
The use of antibiotics as a preventative treatment for livestock is also thought to have contributed to the problem.
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