USF scientists invent mighty medical mite

USF chemists have developed new synthetic antibiotics and a nano-sized delivery system that successfully attacks drug resistant bacteria in the body.

Due to the overuse of antibiotics, certain bacteria, specifically methicillin-resistant staph, have become resistant to even the most powerful antibiotics said Edward Turos, a professor in USF’s Department of Chemistry.

MRSA bacteria are responsible for most of the hospital-borne infections as well as those found in nursing homes, Turos said.

He added that the drugs used now have a very broad spectrum in terms of what type of bacteria they attack, allowing opportunities for resistance to develop because it is putting tremendous pressure on the bacteria for survival. Because bacteria microbes swap genes, once one figures out a resistant strategy it is able to transfer that knowledge to other bacterium.

“Once one becomes resistant, you open the can of worms where they can all develop resistance very quickly,” Turos said.

The new synthetic antibiotics developed by Turos and other USF chemists specifically target certain types of bacteria and do not attack other useful microbes in the body. The antibiotics are delivered directly to the bacteria using a nano-sized delivery vehicle that was created by one of Turos’ graduate students, Jeung-Yeop Shim.

“These nano-particles containing synthesized antibiotics are 20 times stronger than commercial antibiotics,” Shim said.

The delivery vehicle is a nano-particle one-millionth the size of a pinhead. The small size of the nano-particle allows it to easily pass through the bloodstream, tissue and possibly even barriers such as a blood-brain barriers, said Turos.

Turos said the nano-particle delivery system is a small polymer ball that is coated with the synthetic antibiotics. This ball travels directly to the targeted bacterium, bypassing all other bacteria, and attaches itself to the wall or membrane of the bacterium. The bacterium assumes the nano-particle is something it can use, like food, and pulls it inside. Once inside, the drug is released in a high concentration and attacks the bacteria, killing it, said Turos.

Turos added, that normally, large amounts of drugs are fed into the bloodstream, and doctor’s hope that some of it will get to the intended bacteria in the body. But this does not always happen.

Because of this nano-sized delivery vehicle, doctors can use lower quantities of drugs, but the small amount used is highly concentrated in the area that it is most needed, said Turos. This helps to reduce unwanted side effects and reduce the amount of drug resistance by bacteria.

“It is kind of like a Trojan horse type approach to getting the drug in at a high concentration,” Turos said.

The process used to create the nano-particles is called “microemulsion polymerization.” Polymerization occurs when you take substances and react them together chemically, said Turos. This reaction causes the substances to form a long network that contains repeating units.

“It is similar to how DNA pieces are linked together, but in this case the polymer creates a ball,” Turos said.

Although researchers do not know why the antibiotics specifically target certain bacteria, they do know that the antibiotics show very high selectivity for the MRSA bacteria.

In addition to helping to destroy bacteria, Turos said he hopes that the nano-particles will be used to help detect certain types of bacteria. Once a drug acts on a bacterium, it will not only kill it, but it will also send out a signal that lets doctors know that the bacterium was detected, said Turos. It will also be able to tell the doctor if the bacterium is a particular microbe over a number of others that are causing an illness.

“So we can use that as a way to monitor concentrations or the presence of these bacteria,” Turos said.

Turos’ graduate student, Shim, also said he sees the detection aspect of the nano-particles and antibiotics possibly being used for a bio-defense system.

“It could easily detect bacteria used for bio-terror, such as anthrax, as well as other diseases. It would also allow for faster detection of the bacteria. Instead of three days, it would only take a few minutes,” Shim said.