New all-polyurethane swimsuits, which are due to banned from January because they are performance enhancing, have prompted a deluge of world records and left swimming's credibility hanging by a thread.
Sjostrom finished 27th at last year's Beijing Olympics but blasted through the Foro Italico's open air pool in an astonishing 56.06 seconds to take the title having swum a 56.44 in Sunday's semi-finals.
"I don't know what is happening right now. It's unbelievable," she told reporters. "This is my best year but I have many years in front of me. I can do better."
Five records fell on Monday after six crumbled like Roman ruins on Sunday.
Ariana Kukors, who broke the women's 200 individual medley record in Sunday's semi-final, bettered the mark again to take gold in Monday's final in a mind-boggling time of 2:06.15.
The American edged out Olympic champion Stephanie Rice despite not even qualifying for last year's Beijing Games.
"It's been a whirlwind the last couple of days," she said.
Brenton Rickard of Australia bagged the first world record of the session in the men's 100 breaststroke final, sending statisticians scurrying after chalking up a 58.58.
PHELPS REMARK
The world records being set could stand for years to come with governing body FINA poised to confirm a return to all-textile suits and trunks for men in 2010.
Michael Phelps, who won a record eight gold medals at Beijing, acknowledged the improved performance of Paul Biedermann after qualifying third behind the German in the 200 freestyle semi-finals.
Biedermann cracked Ian Thorpe's 400 world record on Sunday.
"He has gone six seconds faster in the 400 in a year," remarked Phelps, who is swimming in Speedo's LZR suit which was among the first of the new breed of costumes but has now been usurped by quicker models.
The American could struggle for gold in Tuesday 200 final.
In other world records to fall on the second day of competition, America's Rebecca Soni powered home in the 100 breaststroke semi-finals in 1:04.84.
Anastasia Zueva then made a splash in the semi-finals of the 100 backstroke by triumphing in just 58.48.
The Russian beat Kirsty Coventry's previous best of 58.77 with Gemma Spofforth of Britain then finishing in 58.74 in the second semi-final.
The two biggest surprises on another sweltering Rome day were Olympic champion Aaron Peirsol failing to qualify for the 100 backstroke final and Milorad Cavic grabbing gold in the 50 butterfly final.
American Peirsol said he had miscalculated his swim having stated after the earlier heats that he would have to better his own world record to win Tuesday's final.
Serbia's Cavic swam a championship record of 22.67 seconds to hold off the challenge of Australia's Matt Targett and world record holder Rafael Munoz of Spain.
Photograph: Reuters