I am using a directory program that won't allow commas in my fields. I am unable to escape them, so I'd like to add them in the browser with a find and replace with javascript.

here is the text:

John Q. Smith MD

I want it to read:

John Q. Smith, MD

How do I find " MD" on the php generated page?

Here is my best start:
HTML Code:
<head>

  <script type="text/javascript">
     // define where to seach?
      document.write(str.replace(" MD", ", MD"));
  </script>

</head>
<body>

  <h1>List of Doctors</h1>

  <ul>
     <li>John Q. Smith MD</li>
     <li>Janet Jones MD</li>
  </ul>

</body>