PITTSFIELD — The trial of a former Berkshire County nursing home employee charged with trying to sexually assault a bedridden patient has started with the defense saying the accusation was made by a co-worker with a grudge against his client.Paul Shartrand, of Pittsfield, has pleaded not guilty to charges including assault with the intent to commit rape in the alleged attack on the then 55-year-old patient in August 2012 at the Laurel Lake Center for Health and Rehabilitation in Lee.