The patients condition became worse. Ones real motivation is always self-interest. The apostrophe goes after the a for plurals ending in s. Contractions are always formed with an apostrophe. Not a possessive, this is a contraction of it is.
Lets look at it philosophically.
This is a contraction of let us . This is an easy and absolute rule. As such, they are words that require antecedents. There are these guys I met yesterday. These are beautiful flowers here in your garden.