In five states _ Jalisco, Guanajuato, San Luis Potosi, Nuevo Leon and Tabasco _ the PRI's winning margins on July 6 were thin.
Attempts by The Associated Press to reach Jalisco judicial officials by telephone on Sunday were unsuccessful.
Notimex, citing a police statement, said Jalisco state police arrested Mario Perez, 35, in a Guadalajara hotel late Tuesday.
The bacteria was found in abundance in refrigerators, ants and even in the bodies of employees at the Jalisco plant, he said.
The company will use a new plant in the state of Jalisco.
Most eggs are laid on the Pacific beaches of the states of Oaxaca, Michoacan, Guererro and Jalisco.
Even worse, its sitting governors in Tabasco, Jalisco and Michoacan resigned under intense opposition pressure. The resignations followed those last year in Guanajuato and San Luis Potosi after the opposition cried electoral fraud.