Food-borne illnesses Are not always Home-grown

A team of researchers compared the genome sequences of nearly 400 samples of diarrhoea-causing Salmonella enterica collected from people and livestock in Scotland. They found that bacterial strains infecting humans were largely distinct from those found in local cattle, but had close ties to strains that had been isolated in other countries. The result comes from a detailed study of DNA from more than 370 Salmonella samples collected over a 22-year period.

By studying the genetic variation in the Salmonella bacteria and their drug resistance genes, researchers found that distinguishable bacterial populations exist in human and animal populations living side by side. Antibiotic resistance is considered to be one of the most important dangers to human health, threatening to make many treatments to common infections ineffective. By comparing the genomes of Salmonella in humans and animals the researchers have provided important new insights into the likely sources and spread of antibiotic resistant infections. First, the Salmonella bacteria largely remained within their original host populations and second, there were more varied combinations of drug resistance in the human-infecting bacteria.

Salmonella infection is a global issue, with approximately 94 million people contracting gastroenteritis or food poisoning each year. The combined annual cost in the United States and European Union is estimated to be more than £4 billion ($6 billion). This public health issue is exacerbated further by antibiotic resistance, which can lead to more complicated and protracted illness in patients and increased treatment costs.
Sources: Sciencedaily

Images: • Color-enhanced scanning electron micrograph showing Salmonella Typhimurium (red) invading cultured human cells
Credit: Rocky Mountain Laboratories, NIAID, NIH

• Scotland's highland cows have been badmouthed as promoters of salmonella outbreaks, but the bacteria may have come from abroad instead.