BUDAPEST, Hungary -- Canadian 15-year-old Summer McIntosh won another gold medal and Italy pipped the United States to the men's 4x100 medley relay title on the final night of racing at the world swimming championships.
The American women clinched the Unites States' record 45th medal of the week by winning their 4x100 medley final. Regan Smith, Lilly King, Torri Huske and Claire Curzan were 0.47 seconds ahead of Australia and 1.23 ahead of Canada.
Canadian swimmers finished with 11 medals for their most successful worlds.
Veteran Gregorio Paltrinieri also won a thrilling men's 1,500 freestyle on Saturday, as Italy ended the week's swimming events with five golds.
Paltrinieri was well under world record pace as he built a huge lead over his rivals before eventually finishing in a championship record 14 minutes, 32.80 seconds.
Only Sun Yang's world record of 14:31.02 from the 2012 Olympics has been faster. The Chinese swimmer is suspended for a doping violation.
Bobby Finke, who has made an art of finishing strongly to overtake rivals, was unable to catch Paltrinieri as he finished 3.90 behind in an American record 14:36.70. Finke's silver was America's record-breaking 39th medal this week, eclipsing its tally from Budapest in 2017.
Germany's Florian Wellbrock was third.
McIntosh wrapped up a highly successful week for Canadian swimming with her second world title, clocking 4:32.04 in the women's 400 individual medley. It was yet another world junior record for the teen.
Katie Grimes, who is just seven months older than McIntosh, pushed her rival all the way before finishing 0.63 seconds behind for silver. Another American, Emma Weyant, was third, 3.96 behind.
After some confusion, the United States' Justin Ress was confirmed as the men's 50 backstroke champion.
Ress' elation at winning the race in 24.12 ended promptly when he was disqualified for being submerged at the finish. Teammate Hunter Armstrong, who finished two-hundredths of a second behind, was awarded the win, while the 17-year-old Ksawery Masiuk of Poland was bumped up to silver and Italy star Thomas Ceccon grabbed the bronze.
But -- after the award ceremony -- FINA overturned the disqualification, meaning Ress was awarded gold, Armstrong silver and Masiuk bronze.
Sweden's Sarah Sjöström won the women's 50 freestyle for her 10th gold at a worlds, all in individual events. It was the second time she completed the 50 free/butterfly double at a single worlds after Budapest in 2017.
Italy didn't have it all its own way when Lithuanian swimmer Rūta Meilutytė upset world record holder Benedetta Pilato by one tenth of a second to win the women's 50 breaststroke in 29.70.
But Italian journalists, team officials and support staff applauded when Paltrinieri came through the mixed zone following his tilt at the world record. Ceccon also interrupted Paltrinieri's interviews to give his teammate a hug.
The Italians were celebrating again later when Ceccon, Nicolo Martinenghi, Federico Burdisso and Alessandro Miressi set a European record of 3:27.51 to win the men's 4x100 medley by 0.28 seconds ahead of the Americans.
Team of Italy celebrates winning the men's 4x100m medley relay at the 19th FINA World Championships in Budapest, Hungary, Saturday, June 25, 2022. (AP Photo/Petr David Josek)
Team of Italy celebrates winning the men's 4x100m medley relay ahead of second placed team of the United States, left, at the 19th FINA World Championships in Budapest, Hungary, Saturday, June 25, 2022. (AP Photo/Petr David Josek)
Italy's Gregorio Paltrinieri celebrates after winning the men's 1500m freestyle final at the 19th FINA World Championships in Budapest, Hungary, Saturday, June 25, 2022. (AP Photo/Petr David Josek)
Sarah Sjostrom of Sweden smiles after winning the women's 50m freestyle final at the 19th FINA World Championships in Budapest, Hungary, Saturday, June 25, 2022. (AP Photo/Petr David Josek)
Summer McIntosh from Canada competes during her women's 400m individual medley heat at the 19th FINA World Championships in Budapest, Hungary, Saturday, June 25, 2022. (AP Photo/Petr David Josek)
Summer McIntosh of Canada competes during the women's 400m individual medley at the 19th FINA World Championships in Budapest, Hungary, Saturday, June 25, 2022. (AP Photo/Petr David Josek)
Summer McIntosh of Canada celebrates after winning the women's 400m individual medley at the 19th FINA World Championships in Budapest, Hungary, Saturday, June 25, 2022. (AP Photo/Petr David Josek)
Summer McIntosh of Canada reacts after winning the women's 400m individual medley at the 19th FINA World Championships in Budapest, Hungary, Saturday, June 25, 2022. (AP Photo/Petr David Josek)
Team of Italy celebrates after winning the men's 4x100m medley relay at the 19th FINA World Championships in Budapest, Hungary, Saturday, June 25, 2022. (AP Photo/Petr David Josek)