Cortese's injury, along with Scott Lawson's absence on Scotland international duty, means that Gloucester Rugby enter their preseason friendly campaign with only two fit hookers in England U20 international Koree Britton and Darren Dawidiuk.
Charles started his Super Rugby career with the ACT Brumbies and is a former Australian Schoolboys and U20s international.
And in October 2010 at 21 years of age, he was selected to the Qantas Wallabies Training Squad for the 2010 Spring Tour.
Currently on tour in Samoa with the Western Force, he will link up with the Gloucester Rugby squad very shortly and will be a welcome addition to the squad according to Head Coach Bryan Redpath:
"Nathan's a very highly rated hooker in Australia. He's got Super Rugby experience and has trained with the Wallabies. We're fortunate to be able to bring him in to cover Matias' absence."
"We had to act because if anything happened to Koree or Darren in the preseason games, we'd have no hooker cover for the start of the Aviva Premiership season. So, it'll be good to have him on board."