Around 20 maggots produce one drop of the purified antibiotic
Scientists hope maggots can help produce an antibiotic that can tackle strains of the MRSA superbug.
The researchers at Swansea University are developing the antibiotic from maggot secretions from the common green bottle fly.
They hope to develop it into an injection, pill or ointment to tackle 12 strains of MRSA, as well as as well as E.coli and C.difficile.
The research also involved scientists at universities in Belgium.
The antibiotic has been named Seraticin and scientists have studied how it can prevent infection.
It takes around 20 maggots to make one drop of the antibiotic in its purified form.
Scientists now hope to complete the identification of the compound and find a way to synthesise it, before it can be tested on human cells and trialled to determine its medical effectiveness.
Using live maggots on infected wounds is a well established method of tackling infections.
Professor Norman Ratcliffe, a principal researcher on the project, said: "It has been a huge team effort to get to this level and I am delighted with our progress.
"However there is more to do if we are to realise the maximum benefits from this discovery.
He said the next stage was to confirm its exact identity using mass spectrometry and nuclear magnetic resonance analyses to produce it chemically on a larger scale.
Dr Alun Morgan of ZooBiotic Ltd, based in Wales, that supplied the maggots for the project, said: "Maggots are great little multi-taskers.
"They produce enzymes that clean wounds, they make a wound more alkaline which may slow bacterial growth and finally they produce a range of antibacterial chemicals that stop the bacteria growing."
The research was funded by leading charity Action Medical Research, with support from the Rosetrees Trust.
The University of Manchester has been carrying out similar research, after using green bottle fly larvae to treat diabetic patients, whose foot ulcers were contaminated with MRSA.
They found that most were cured within three weeks, compared to 28 weeks with conventional treatment.