The researchers said the discovery potentially provides new ways to spot and prevent tumours.
In the study published in the journal European Urology Oncology, the researchers said they examined more than 600 patients with and without prostate cancer to assess the usefulness of their urine bacterial tests.
They identified five types of bacteria common in urine and tissue samples from men whose cancers became aggressive.
All were types of bacteria that can grow without oxygen while some were new types never found until now.
Two of the new bacteria species found were named Porphyromonas bobii and Varibaculum prostatecancerukia.
Research shows prostate cancer is not always life-threatening as some tumours grow too slowly to cause trouble.
However, the challenge for oncologists has always been an early diagnosis for men who have fast-growing ones.
The University of East Anglia team involved in the latest study said more work is needed to see if clearing the infection with antibiotics might prevent bad tumours.
“Among the things we don’t yet know is how people pick up these bacteria, whether they are causing cancer, or whether a poor immune response permits the growth of the bacteria,” Rachel Hurst, one of the researchers, said.
“But we hope that our findings and future work could lead to new treatment options, that could slow or prevent aggressive prostate cancer from developing.
“Our work could also lay the foundations for new tests that use bacteria to predict the most effective treatment for each man’s cancer.”
Sam Godfrey from Cancer Research UK, added: “Nearly four in 10 cancers in the UK are linked to known risk factors such as smoking and obesity.
“But there are other cancer-causing risk factors, such as bacteria, that we are only just beginning to identify.”