Winged pests may be far peskier for healthcare providers than imagined, considering a new study reveals that more than half the bacteria the insects carry is resistant to antibiotics.

Antibiotic-resistant illnesses can be especially harmful among frail, elderly populations such as those found in skilled nursing facilities.

A microbiological analysis conducted on almost 20,000 flying insects caught inside a group of English hospitals found such bugs pose a potential infection risk to patients. About 90% of common houseflies, bluebottle and greenbottle flies and so-called “drain” flies tested carried dangerous bacteria such as E.coli, salmonella and Staphylococcus aureus either in or on their bodies.

Researchers with Aston University collected the insects from areas where food-preparation areas and from several patient wards. In some cases, the level of bacteria carried by flying insects was enough to potentially cause infection.

The study ran 18 months, with the most bugs caught in the spring and summer.

Some 53% of bacterial strains found on the bugs were resistant to at least one antibiotic class, and 19% percent showed multidrug resistance.

“The high proportion of drug-resistant bacteria found in these samples (is) a vivid reminder of how our overuse of antibiotics in healthcare settings is making infections more difficult to treat,” Aston doctoral student Federica Boiocchi said in a press release.

Co-author and professor Anthony Hilton, Ph.D., noted that “even the cleanest of environments” need to take steps to prevent insects from carrying dangerous superbugs through their doors.
The full study was published online last week in the Journal of Medical Entomology.