Earlier, O’Callaghan, who won gold medals in both the 200m freestyle and the 400m and 800m relay, won four gold medals in the tournament.
O’Callaghan is the first female athlete to win both 100m and 200m freestyle gold medals at a single world championship.
There have only been two athletes who have won the men’s 100m and 200m freestyle simultaneously at the previous world championships. Jim Montgomery (USA), the first competition in 1973, and David Popovich (Romania), the Budapest competition last year, achieved this.