Substitution element value instead of number

In a separate file is stored an array of specialties and doctors. The information is entered into the database: the specialty is a word (line) and the doctor is a number. How to make, that at sampling of records from a DB, instead of digit, the name of the doctor was substituted?

$listt= array ( 'Педиатр' => array ( 0 => 'Ольга Ганжа', 1 => 'Александра Смердова', 2 => 'Елена Гусева', ), 'Терапевт' => array ( 0 => 'Владимир Райко', 1 => 'Кудайбердиева Анар', 2 => 'Валентина Бочанова', 3 => 'Татьяна Кочеткова', ), 'Хирург' => array ( 0 => 'Андрей Сверидюк', 1 => 'Николай Никитин', ) );