Hardly dueling Scots, though.
Fleming's Cheadle Prize winning medical essay "DIAGNOSIS OF ACUTE BACTERIAL INFECTIONS" (the only time I know of that he seriously engaged the subject of endocarditis) was written in 1909 and published in the ST MARYS HOSPITAL GAZETTE (volume15 , pages 67-69,72-77).
Most biographers of Fleming felt this early essay nevertheless set out the course of his life's work - which extended for another 45 years - so it is well worth a close reading.
Dawson confounded the essay's conclusions on intravenous injections to treat endocarditis in March 1942, with his first success in reducing bacterial colonies in endocarditis patient's blood.
Critics of vaccines said endocarditis's constant shedding of small amounts of bacteria directly into the bloodstream should lead to a natural immunity against them but instead actually only led to death.
Fleming dosed himself with a staphylococcic vaccine via an intravenous injection directly into the bloodstream.
(Staph was then a far less virulent bacteria than it is today.)
He lived, having only a slight headache and fever, but gained no increased resistance to staph.
Intravenous injections of vaccines gave maximum infectious effects and minimal increases in natural antibodies said Fleming.
Despite the fact that all of Fleming's considerable wealth came from his great skill in injecting the very dangerous drug Salvarsan directly into veins, he seemed dubious on 'systemic' or intravenous medications in general.
I think this is partially why he never tested penicillin as a systemic medicine in humans - or animals.
Not till 1940 did Dawson do so for humans and Florey for animals...