The cucumbers were said to be imported from Mexico and were then packed by US produce companies for shipment across the county...resulting in illnesses in 33 states.
In 2014, there was a Salmonella outbreak associated with cucumbers from Maryland and in 2013, an outbreak of E.coli O157:H7 associated with slice cucumber on sandwiches.
The pH of cucumbers is approximately 6. While there are limited studies on the growth of Salmonella on cut cucumbers, evidence suggests that there may be a slow increase in numbers when the product is stored at non-refrigerated temperatures. This may compound the primary issue, which is that cucumbers are grown on or near the ground, and if that ground is contaminated, such as occurs when using improperly treated manure as a fertilizer, then that contamination is transferred to the cucumbers (via direct contact, hands, splashing water, little critters, etc) could adhere to the surface of the cucumber. Using contaminated irrigation water can lead to contamination of the cucumbers. Finally, cucumbers can become contaminated during handling and rinsing / hydrocooling. Point source contamination issues in the packing house can spread that contamination to a large number of cucumbers. More study is needed on cucumbers and contamination issues associated with growing, harvesting, storage and consumer handling.