Virus found in sewage shows promise in treating dental procedure infections

Date: Feb-19-2015The rise of superbugs is spurring research into alternative ways of fighting

resistant bacteria that cause serious infections. One such avenue is a revival of an

old idea - using viruses to infect and eliminate bacteria.

30,000 times magnified image of phages shows some still binding to dead bacteria.
Image credit: Ronen Hazan / Hebrew University

Bacteriophages - or "phages" - are viruses that infect bacteria. Through a long

history of co-evolution with bacteria, they have evolved into highly effective

"professional killers" of the bugs.

Back in the days when drugs were first developed as a way to treat bacterial

infections, scientists were already thinking about using phages to fight bacteria,

but then put the idea to one side as antibiotics became successful.

Now, decades later - as we face the daunting prospect of a post-antibiotic era - the idea of using phages or

viruses to kill bacteria is receiving attention again.

A good example is a new study from researchers at the Hebrew University of

Jerusalem's Faculty of Dental Medicine, who describe their findings in the journal

Applied and Environmental Microbiology.

An intriguing fact about the virus the team studied - a phage called EFDG1 - is

that they isolated it from Jerusalem sewage.

The study shows that EFDG1 could be an effective way to kill a very

stubborn, drug-resistant bacterium called Enterococcus faecalis that can

sometimes cause infections following dental procedures.

E. faecalis is a bacterium found in the human gastrointestinal tract. It

is a dangerous pathogen that causes endocarditis (potentially fatal heart

infection), bacteremia (harmful bacteria in the bloodstream) and other serious

infections, such as urinary tract infection, meningitis and - as in the subject of

this study - post-treatment root canal infection.

One of the things that makes E. faecalis difficult to treat is because

it forms a biofilm - where the bacterial cells cluster and stick to surfaces by

excreting a slimy, glue-like substance.

E. faecalis is often recovered from persistent infections associated

with root canal treatments, and infection can persist in up to a third of root

canals. This high rate of infection limits the choice of treatment options, so

researchers are keen to find ways to eliminate E. faecalis, especially when

in biofilm form.

The phage almost entirely eradicated E. faecalis in liquid culture and

biofilm

For their study, the team tested how well EFDG1 killed E. faecalis cells

- both in a liquid culture and in biofilm form. They already knew the phage was

capable of infecting the V583 strain of E. faecalis, which is resistant to

vancomycin, the most effective antibiotic against the bacterium.

The tests showed EFDG1 almost entirely eradicated E. faecalis -

both in liquid culture and biofilm form.

The team also showed EFDG1 was highly effective at eliminating E.

faecalis in tissue examples of root canal infection, suggesting that phage

therapy using EFDG1 might be an effective way to prevent E. faecalis

infection following root canal procedures.

Using transmission electron microscopy and whole genome sequencing, the team also determined

that the EFDG1 phage belongs to a subfamily of the Myoviridae phages, which

may offer other candidates for treating bacterial infections.

The team also found that the EFDG1 genome does not appear to contain

harmful genes, suggesting it may be safe to test its effectiveness at dealing with

E. faecalis in humans.

One of the study leaders, Dr. Ronen Hazan, from the Institute of Dental Sciences

at the Hebrew University, says:

"As this research shows, bacteriophages may prove an effective tool

in the development of much-needed new antimicrobial drugs."

In November 2014, Medical News Today learned of another study reported

in the same journal that showed  saliva protects

teeth  against cavities more than we thought. It appears that salivary mucus

contains compounds that actively protect teeth from damage by the cavity-causing

bacterium Streptococcus mutans.

Written by Catharine Paddock PhD

Courtesy: Medical News Today Note: Any medical information available in this news section is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.