It has been said that the increasing risk of antibiotics resistance poses as big a risk to our time as terrorism. Bacteria are continuously evolving to become more and more resistant to antibiotics. Previously this wasn’t such a problem, because new antibiotics were being constantly developed so doctors could switch to new prescriptions. But the pipeline for new antibiotics is looking almost empty, with no incentives for pharmaceutical companies to develop new antibiotics as they are used irregularly and resistance limits their lifespan. Increased antibiotic resistance could mean the end of complex operations, like heart, bone and bowel surgery and the end of cancer treatments, where antibiotics are used to ward off infections to patients compromised immune systems.
We recently blogged about antibiotic resistance and the Longitude prize, but with European Antibiotic Awareness Day upon us we thought we might look again at this topic and see what the options are in the face of this global crisis.
The Dutch biotechnology company Micreos unveiled a new drug earlier this month that may prove effective as an antibiotic alternative1. Already available within specialist creams to treat infections in acne, eczema and skin irritations Staphefekt is based on an endolysin; an enzyme found in bacteriophages that kills bacteria. Viruses invade bacterial cells to replicate and once enough virus particles have been generated they use endolysins to destroy the cell wall and disperse. As Staphefekt targets the bacterial cell wall and not the metabolic pathways, which harbour the ability to resist, it is less prone to resistance induction than antibiotics and bacteria that are resistant to antibiotics will be susceptible to it. The drug has also been found to only target specific bacteria, leaving the beneficial strains unharmed, which may prevent secondary infections from species such as Clostridium difficile and Candida albicans. In an observational study the use of Staphefekt killed MRSA in five out of six patients suffering skin conditions including eczema and dermatitis. Micreos are making the drug available free for research purposes and is to conduct clinical trials of Staphefekt.
Scientists from the Scripps Research Institute have modified the traditional antibiotic vancomycin, by modifying the bacterial cell wall binding pocket of the drug and adding a chlorobiphenyl group2. This resulted in a potent molecule with impressive activity against a range of bacteria including MRSA and vancomysin-resistant enterococci in laboratory studies. The researchers are now working towards optimising the synthesis process before beginning trials in animals.
Many farmed animals are administered antibiotics to promote weight gain, resulting in antibiotic-contaminated waste. Continuous contact with these antibiotics in manure can lead to the bacteria in animals and their farmers developing antibiotic resistance. Vermicomposting, uses pests such as worms and flies to reduce waste and convert the harmful contaminants inside it. Scientists in Hangzhou, China have been using the common house fly to turn over pig waste at a factory farm and noticed that 70% of the antibiotic contaminant disappeared within six days3. Traditional composting and anaerobic clean-up solutions are deemed too expensive for the sheer amount of waste produced in the farming industry, particularly in developing countries.
Leaf cutter ants from Central and South America aren’t actually able to eat the leaves they cut. Instead they feed these leaves to a fungus on which they feed. The fungus is farmed in large fungus gardens underground, but should this garden become infected by either bacteria or another fungus the whole ant colony will die. To prevent this the ants host bacteria on their bodies, feeding them through glands, and in return the bacteria produce an antibiotic which is used by the ants to prevent infection of their fungal food source. The antibiotics being produced by these ants have never been seen before and despite having used this system for the past 50 million years they have no problems with drug resistance due to their wise use of these drugs. The bacteria which the ants carry are of the genus actinomyces, which we currently derive antibiotics from. Dr Matt Hutchings’ lab at the University of East Anglia4 is screening the bacteria on these ants to isolate strains and have discovered four new strains which are effective against fungus resistant to all other anti-fungal compounds. They are currently attempting to isolate the structures of the antibiotics used by the ants for their potential use in medicine.
Antibiotics cannot treat colds, coughs or sore throats and limiting our use of these life-saving medicines may prolong their efficacy, whilst we attempt to find a new source of such potent drugs, yet it’s good to know that there is a possible light at the end of the tunnel into which we seem to be headed, or at least people working to make it so.
References1. http://www.micreos.com/news/dutch-biotech-micreos-launches-first-bacteria-killing-enzyme-for-human-use-against-mrsa.aspx (link is external) 2. Okano et al. Journal of the American Chemical Soc. 136(39); 13522-13525 (2014) 3. Zhang et al. Sci Reports doi: 10.1038/srep06844 4. http://www.uea.ac.uk/leafcutter-ants/home (link is external)