London - Antibiotic resistance has been declared as big a threat to our safety as terrorism — but now scientists are testing a new “designer” form of the drugs that may reduce the problem.
This style of antibiotic targets the specific strain of bacteria causing the illness, so that the other strains are left unharmed and don’t become resistant.
Already, an estimated 5 000 people die each year in the UK as a result of infections caused by bacteria that no longer respond to antibiotics.
Antibiotics work by either killing harmful bacteria outright — for example, by destroying their cell walls — or by stopping them from multiplying. They transformed medical care after their introduction in the Forties, but their high success rates led to widespread and often inappropriate use, which has, over time, encouraged the spread of antibiotic resistance in bacteria.
Every time a patient takes antibiotics, sensitive bacteria are killed, but some resistant germs may be left to grow and multiply.
Part of the problem is most traditional antibiotics have a broad brush approach — meaning that, along with the harmful bacteria, they can destroy many of the harmless strains that live in and on the body, allowing resistant bacteria to multiply quickly and replace them.
Now, a new wave of drugs is being developed that target a single type of bacteria, in the hope they will slow the rise of resistance.
Swiss company Debiopharm is developing Debio 1450 and 1452 to target Staphylococcal bacteria, the bugs that commonly cause skin infections such as impetigo, which is highly contagious and causes sores and blisters.
The drugs work by targeting compounds the bacteria need in order to reproduce. already, they have been shown to have a 93 percent cure rate in trials.
Because these antibiotics are tightly focused on Staphylococcus species, they do not damage other bacteria in the gut, therefore reducing the risk of these others becoming resistant. This also means there are minimal antibiotic-associated side-effects, such as diarrhoea.
Antibiotic resistance has become a serious health threat, with infections that were previously treatable with standard antibiotic drugs — such as tuberculosis, gonorrhea and E.coli — now often needing to be tackled with more than one drug.
Resistance has also been shown to be increasing in “gram-negative” bacteria, which are linked to a number of infections, including urinary tract ones, particularly in hospitalised patients. A decade ago, two percent of E.coli from bloodstream infections were resistant to the cephalosporins group of antibiotics and four percent to another antibiotic, ciprofloxacin. Those rates have now climbed to 11 and 21 percent.
Some so-called multi-resistant bacteria have become immune to many drugs, the best known being Methicillin-resistant Staphylococcus aureus, or MRSA.
“Gram-negative bacteria, which are found in the gut and which are involved in urinary infections, are a particular worry,” says Philip Howard, consultant antimicrobial pharmacist at the Royal Pharmaceutical Society. “The emphasis now is on the development of antibiotics with a much narrower focus to treat the most resistant bacteria.”
Some antibiotics have already been lost to resistance. Penicillin is no longer effective for Staphylococcal wound infections, and ampicillin is not now usable for infections of the urinary tract, while ciprofloxacin can no longer treat gonorrhea; other drugs or combinations are used instead.
The problem has been that there are precious few new antibiotics coming along.
“Large pharmaceutical companies are not investing in antibiotic research, because there is insufficient return on investment, compared with drugs for chronic conditions, such as statins,” says Professor Alan Johnson, an antibiotics expert for Public Health England.
“I suffer from hay fever and will take antihistamines for the rest of my life, but people only use antibiotics for short periods, often less than a week.
“There is urgent need for action to encourage the development of new antibiotics.”
Oral and intravenous versions of the new Debio drugs are being developed and have already been used in human trials.
Research shows the drugs are highly potent against all Staphylococcus species, including all known resistant strains, such as MRSA and Vancomycin-Intermediate Staphylococcus aureus (VISA).
In a study of skin infections due to Staphylococcus, there was an overall cure rate of 93 percent.
“There is a real need for new antibiotics like this, especially those that allow the host protective bacteria ‘gut flora’ to survive,” says Dr Howard.
“Recent data shows that most C.diff diarrhoea infections are probably due to upsetting a patient’s gut flora, which allows low levels of the harmful bacteria to multiply and cause problems.
“Where possible, maintaining the gut flora will be protective, so will be a positive attribute of any new antibiotic.” - Daily Mail