The 26-year-old started last season in npower League Two with Rotherham, but he has had no problem stepping up to the Barclays Premier League.
Le Fondre took his tally for the season to 12 on Wednesday night when he scored a vital late brace to help Reading earn a 2-2 home draw against European champions Chelsea at the Madejski Stadium.
The striker has scored vital late goals in his team's last three league games, earning him the moniker of Reading's super sub.
McDermott insists Le Fondre is good enough to star for his team for 90 minutes, however, and even believes the Stockport-born hitman is capable of playing for England.
"I spoke to Ray (Lewington, England assistant) this morning [Thursday], he was at the game on Wednesday night and I don't see any reason why Adam Le Fondre can't play for his country," McDermott told TalkSPORT.
"He finishes when he gets a chance. He couldn't have been under any more pressure there but he produced. I'm not saying he can only score from the bench, I would never ever say that.
"I'm not picking Roy Hodgson's team, but I would say Alfie (Le Fondre) could score for England from the bench or score for any team. His record is phenomenal."
Le Fondre's exploits up front this season mean Reading's failure to sign Blackpool forward Thomas Ince on Thursday will not be such a big blow for the Berkshire club.
Reading had lodged a bid to sign the son of former Manchester United and England midfielder Paul Ince, but it is understood that McDermott has now given up all hope of landing the 21-year-old.
Wednesday night's draw, meanwhile, further eases the pressure on McDermott's shoulders.
The 51-year-old was odds-on favourite for the sack in the first half of the season, but he has turned the club's fortunes around over the last month.
Reading owner Anton Zingarevich said following Wednesday night's draw that he never thought about changing manager even when Reading were at their lowest ebb.
"I always trusted Brian," the Russian said.
"It's a new experience for everybody. We have to learn a little. I never had hesitations.
"We knew it was going to be difficult. Every team in the Premier League has good players.
"We're playing against direct competitors at home now. We all feel really confident."