Hi Phil,

Thanks for your comments. We are backing up the transaction log every 15 minutes. This article has been written for particular situation that is mention below:

According to SQL Server BOL (http://support.microsoft.com/kb/317375):

“These transactions, such as uncommitted transactions, are not deleted after checkpoint or after you back up the transaction log until the log-reader task copies the transactions to the distribution database and unmarks them. If an issue with the log-reader task prevents it from reading these transactions in the publisher database, the size of the transaction log may continue to expand as the number of non-replicated transactions increases.”

I think this is the known issue.