Hugh Hefner reportedly died from cardiac arrest in addition to experiencing respiratory failure.
The strain of E. coli was apparently so severe that it was "highly resistant to antibiotics."
Hefner passed away at the age of 91 last Wednesday. He died at the Playboy Mansion surrounded by friends and family. Playboy confirmed his death in a statement to E! News.
"Hugh M. Hefner, the American icon who in 1953 introduced the world to Playboy magazine and built the company into one of the most recognizable American global brands in history, peacefully passed away today from natural causes at his home, The Playboy Mansion, surrounded by loved ones," Playboy stated. "He was 91 years old."
He was laid to rest the following Saturday, TMZ reports. The father of four was buried directly next to Marilyn Monroe. Back in 1992, he purchased the burial spot for $75,000.
This particular burial location held sentimental value for Hefner as Monroe was the first woman to be featured in the premiere issue of Playboy in 1953.
Crystal Hefner, Hugh's widow, spoke out for the first time on Monday.
"We laid him to rest Saturday," she told People. "He is in the place he was always certain he wanted to spend eternity."
Crystal continues, "He was an American hero. A pioneer. A kind and humble soul who opened up his life and home to the world. I felt how much he loved me. I loved him so much. I am so grateful. He gave me life. He gave me direction. He taught me kindness. I will feel eternally grateful to have been by his side, holding his hand, and telling him how much I love him."
Hefner is survived by his four children — daughter Christie, 64, and sons David, 62, Marston, 27, and Cooper — and his third wife Crystal, 31.
After his death was announced, a bevy of celebrities took to social media to react to Hefner's passing. See the celebrity tributes to the late American icon here.