Fighting foodborne disease

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Related tags: E. coli, Escherichia coli

Enterobacter sakazakii, a bacterium that can be dangerous to
premature babies and young infants, could be more widespread than
previously thought, according to recent research published in this
week's issue of The Lancet. In previous outbreaks, infant
formula contaminated during factory production was recognised as a
source for bacterial colonisation, but the degree of wider
environmental contamination has been relatively understudied.

To gain a better understanding of the issue, scientist Chantal Kandhai from Wageningen University, Netherlands, used a refined isolation and detection method to investigate the presence of E. sakazakii in various food factories and households. Environmental samples from eight of nine food factories and from a third of households - five out of 16 - contained the bacterium.

Kandhai and his colleagues believe that an appreciation of the widespread nature of this micro-organism needs to be taken into account when designing preventive control measures.

"Current industry efforts to reduce the occurrence of E sakazakii have focused on improving hygiene practices, coupled with environmental monitoring and end-product testing for the organism,"​ said Jeffrey Farber from Health Canada. "Since powdered infant formula is not sterile and there is the potential risk of contamination during preparation, there is a need for care when preparing and handling reconstituted powdered infant formulas. Health-care professionals should follow recommendations provided by public-health officials and organisations such as the American Dietetic Association, and be alert to possible modifications."

The New Year has brought some good news in the fight against foodborne disease, however. New tests conducted by the US Agricultural Research Service (ARS) have significantly reduced the time taken to identify dangerous strains of the harmful bacteria Escherichia coli​. Sixty-one deaths and 73,000 illnesses are blamed on eating foods contaminated with E. coli each year, according to the Centers for Disease Control and Prevention.

Certain E. coli strains, such as O157:H7, causes serious diseases, including bloody diarrhea and hemorrhagic colitis. Infections may result in serious health complications, including kidney failure. Other E. coli serogroups, including E. coli O26, O111 and O121, also cause gastrointestinal illnesses in humans.

Currently, scientists commonly use a procedure called serotyping to distinguish between different types of E. coli - some harmful, others harmless. However, this procedure is time-consuming and labour-intensive. Pina Fratamico at the ARS's Eastern Regional Research Center (ERRC) is developing both conventional and real-time polymerase chain reaction (PCR) tests. These chemical procedures generate enough of a bacterium's genetic material so that it can be studied and identified. With one real-time PCR reaction, four products can be amplified simultaneously and detected in "real time" as they multiply.

Scientists have little information about some individual E. coli serogroups, therefore, the number of diseases these organisms cause is likely underestimated, report the scientists. Fratamico is targeting genes in the E. coli O-antigen gene clusters so researchers can detect and identify specific serogroups and increase knowledge about each one's potency.

In one study, a real-time PCR assay was more sensitive than other detection methods. According to Fratamico, the US Department of Agriculture's Food Safety and Inspection Service has expressed interest in the new PCR tests for detection and confirmation of E. coli O157:H7 and a range of other E. coli strains.

In September 2003, the US government reported that the number of ground beef samples tainted with harmful E. coli bacteria had dropped. Inspectors found 0.32 per cent of 4,432 samples of hamburger meat tested positive for E. coli from January to August this year, said Elsa Murano, the Agriculture Department's undersecretary for food safety. That compares with 0.78 per cent for the same period in 2002 and 0.84 per cent in 2001. The agency has been testing 7,000 samples each year since 2001.

Related topics: Food Safety & Quality

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