Scientists have expressed serious concern about the sudden emergence of a strain of the Salmonella bacteria - one of the main causes of food poisoning - which appears to be resistant to almost all antibiotics.

An international team has carried out extensive studies into the bacteria, known as Salmonella Kentucky, and found that it is resistant to many antibiotics, including fluoroquinolone, which is one of the main antibiotics used to treat severe Salmonella infections.

The researchers, who have traced the bacteria's development over the last 50 years, originally noticed the bacteria in parts of Africa and the Middle East. However, between 2002 and 2008, some 500 cases of the infection were found in the UK, France and Denmark and between 2009 and 2010, a further 270 cases were detected in France alone.

The team describes the bacteria's evolution as a ‘spectacular explosion' and said it is now ‘taking root in Europe'. Poultry appears to be the main food affected.

Furthermore, the research now indicates that Salmonella Kentucky is becoming resistant to newer ‘third generation' antibiotics.

"These antibiotics constitute the last therapeutic protection against the bacteria. As such, the spread of resistance to the epidemic Salmonella Kentucky strain would represent an impasse in the treatment of these infections," the scientists warned.

They emphasised the importance of monitoring all bacteria that are responsible for food-borne infections and also warned against the unregulated use of antibiotics in the farming industry, which they said, encourages the spread of drug-resistant genes in bacteria.

Details of these findings are published in the Journal of Infectious Diseases.