Bacteria concerns raised in leafy green packaged salads

The aim of the tests on packaged leafy greens was to asses for several types of bacteria including total coliforms and Enterococcus – which can signal inadequate sanitation and provide the potential for presence of disease causing bacteria, said the group.

CU added that the method of packaging – clamshell or bag – made no difference to the bacteria levels detected.

No federal standards​

While there are no existing federal standards for indicator bacteria in leafy greens, industry consultants told the CU that an unacceptable level would be 10,000 or more colony forming units per gram (CFU/g).

It found that 39 per cent of the samples it tested exceeded this level for total coliform, and 23 per cent for Enterococcus.

The tests found no evidence of the presence of the potentially deadly bacteria E.coli O157:H7 or Listeria monocytogenes, although the CU said it had not expected to detect these bugs given the small size of the sample.

The group said it had commissioned an outside laboratory to test 208 containers of 16 brands of salad greens, sold in plastic clamshells or bags, bought last summer from stores in Connecticut, New Jersey, and New York

“Although these ‘indicator’ bacteria generally do not make healthy people sick, the tests show not enough is being done to assure the safety or cleanliness of leafy greens,”​ said CU senior scientist Dr Michael Hansen. “Levels of bacteria varied widely, even among different samples of the same brand. More research and effort is needed within the industry to better protect the public. In the meantime, consumers should buy packages of greens that are as far from the use-by date as possible.” ​

He urged the Senate to act immediately by passing the food safety bill S. 510 that currently requires the Food and Drug Administration (FDA) to set performance standards and develop safety standards for the growing or processing of fresh produce.

“FDA should also formally declare that certain pathogenic bacteria—such as E. coli O157:H7, Salmonella, and Listeria—be considered adulterants when found in salad greens,”​ added Hansen.

Other findings​

The CU said other notable findings included that two percent of samples exceeded French, and five percent Brazilian, standards for fecal coliform bacteria. Many packages containing spinach, and packages which were one to five days from their use-by date, had higher bacterial levels. Packages six to eight days from their use-by date generally fared better.

It added that whether the greens came in a clamshell or bag, included ‘baby’ greens, or were organic made no difference in bacteria levels.