The Red Rose now have to hope Ireland can defeat France on Friday night to keep alive their hopes of regaining the Six Nations crown.
But to have any chance they have to down Italy and Street has only retained wing Katherine Merchant, prop Rochelle Clark, lock Tamara Taylor and flanker Maggie Alphonsi from Friday's 35-3 win over Wales.
"Having such depth of quality players in our squad does make it a challenge to keep consistency but as this is our last game before the World Cup we have got to give players game time," said Street.
"We have not weakened the squad at all but given it a fresh boost before our last game of the Six Nations.
"It's great to have a fully fit Danielle Waterman back in the squad who I hope can add something different to the team, while Natasha Brennan very much impressed on her debut last week and it is vital we see more of her.
"Katy Mclean has been outstanding as captain and at fly half this season but we have a very able back-up in Ceri Large at 10, who also needs to get some more game time under her belt."