No traces of the food poisoning bug Yersinia was found in Foodstuffs Living Foods property and processing plant.
Foodstuffs has released the results of testing carried out at the location where its pre-packaged Pams lettuce is grown and packed.
The results showed no Yersinia pseudotuberculosis was detected in any samples.
"Multiple soil samples were taken from the quarantined paddock and across the farm, all of which failed to detect an evidence of Yersinia pseudotuberculosis," said Foodstuffs NZ spokeswoman Antoinette Shallue.
"In addition, samples of irrigation and processing water, and swabs from the processing plant and final product tests also failed to detect any presence of Yersinia pseudotuberculosis."
"The outcome of our internal audit of the Living Foods processing facility and farm has indicated that they have a high level of food safety compliance and good farm management practices in place.
"There were no uncontrolled practices, conditions or incidents which could have contributed to or led to the food poisoning outbreak."
Ms Shallue said Foodstuffs has a high level of confidence there was no risk of contamination from any product sourced from Living Foods.
"We are confident in the ongoing supply of all products originating from Living Foods and we have reached the conclusion that there was either no contamination at the source or the food safety protocols in place with our supplier were working as required to eliminate such common environmental organisms," says Shallue.
"We are pleased to be able to confirm to our customers that all Pams lettuce products sold in our stores are safe and the scientific testing results have proved this."