Deli meats produced at Maple Leaf’s Bartor Road processing plant in Toronto are cleared to leave the plant if they came off other processing lines besides the one that’s turned up further contamination with listeria.

The Bartor Road plant had been shut for deep cleaning after its production was linked to several dozen cases of listeriosis poisoning earlier this summer. It reopened last month, with all its output ordered held for further testing – at which point new samples from one production line turned up contaminated.

The production line in question “will not be permitted to operate until appropriate corrective action has been taken by the facility and its effective implementation has been demonstrated to the standards established by the CFIA,” the Canadian Food Inspection Agency said last week.

But all other production lines at the plant have “repeatedly” tested negative for any contamination, and a Health Canada risk assessment has found that all products from those lines can be released for distribution, CFIA said.

CFIA and Health Canada are overseeing a staged process for distribution to resume from Bartor Road. Each production run will still be held until samples are all confirmed negative for listeria.

Testing levels will be “further reviewed and adjusted over time” based on how effective the plant’s safety measures are found to be, CFIA said.

Maple Leaf shut down the plant Aug. 20 and recalled all 191 products made there from Jan. 1, 2008 onward. It said last month the “most likely” source of contamination was a possible collection point for bacteria “deep inside the mechanical operations” of two specific meat slicing machines.

Listeria monocytogenes, the bacteria that causes listeriosis infections, occurs naturally and can’t be completely eliminated from the environment, CFIA said previously, but surfaces such as slicers that are in direct contact with food must be “100 per cent free of contamination.”

The plant’s output was connected to a specific strain of listeriosis, which is confirmed to have sickened 54 people in seven provinces, mostly in Ontario.

Among those confirmed cases, 29 people have died and 20 of those deaths were found to be due or partly due to listeriosis, as per the death certificate or an attending doctor’s assessment, the Public Health Agency of Canada said Oct. 17.