Washington died in 1799. His doctors had no knowledge whatever of streptococci. Later, much later, doctors speculate on what Washington might have had.
If he did have a streptococcal infection (strep throat to you), there would have been no treatment for it at the time, although one of the doctors apparently did suggest a tracheotomy, which actually might have saved his life.
Bleeding was not effective for his illness. It would have done no good whatsoever. However, the amount of blood removed from the President would have weakened him significantly, probably hastening his death.
Had he been alive after 1945, he would have received a penicillin shot and recovered quickly. Sadly, he lived in an essential pre-scientific period and died from being treated badly, even though no effective treatment was available to his physicians.
What later doctors have to say about what was probably wrong with Washington has no bearing on this discussion, though. He was bled by his doctors. He died. Science would have saved him, but he was born a bit too early for that.
There is no good evidence he died as a result of the leeches. Most likely pneumonia.