January 28, 2011

Household Bugs: A Risk to our Health?

(Ivanhoe Newswire) -- Superbugs aren't just a concern when walking through a hospital. They could also be coming from our animal farms. According to a new study, insects could be responsible for spreading antibiotic-resistant bacteria from pigs to humans.

Ludek Zurek and collaborators from Kansas and North Carolina State Universities isolated bacteria from farm pig feces and compared them to the bacteria present in the intestines of the house flies and German cockroaches caught on those farms. They subjected the bacteria to a variety of different antibiotic resistance testing and genetic analysis and found that not only were the same types of bacteria carried in the intestines of all the insects and pigs, but there was also a high prevalence of antibiotic resistance. In particular, the common gut bacteria Enterococcus faecalis and Enterococcus faecium were found to be repeatedly resistant to tetracycline, erythromycin, streptomycin, and kanamycin -- common antibiotics used to treat human infections.

The significance of these findings could be important for public health. "In the USA, antibiotics are widely used in pig farming as growth promoters; they cause the pigs to gain weight faster. As a result, the digestive tract bacteria in pigs are often exposed to selective pressure, and many become resistant to antibiotics," Dr. Zurek was quoted as saying. "Consequently, there's a risk that these bacteria might be transferred by common livestock and urban pests such as house flies and cockroaches from pig farms to humans, moreover, since we found such a good match between enterococci from pig feces and insects, it is possible that flies and cockroaches carry other microbes originating from swine feces with even greater public health importance and may transport them to the surrounding urban environment."

There seems to be no risk to humans if they eat properly cooked pork meat, according to the researchers. The widespread use of antibiotics in confined pig production is likely to only increase the selection and evolution of antibiotic-resistant bacterial strains. While farm pigs continue to share their homes with insects, the risk of these resistant strains being transferred to humans via cockroaches and flies is a constant possibility. Effective management strategies aimed at reducing insect pest populations should be an important component of pre-harvest food safety efforts on animal farms.

SOURCE: BMC Microbiology, published online January 25, 2011