The research, “Preoperative urine culture is unnecessary in asymptomatic men prior to prostate needle biopsy,” appeared in the journal International Urology and Nephrology.
Using a needle to obtain a small amount of prostate tissue to examine is the standard procedure for diagnosing prostate cancer. In fact, more than one million prostate biopsies are performed annually.
Because a post-biopsy infection can lead to hospitalization and even death, however, researchers have been studying ways to reduce this risk.
The American Urological Association recommends that a man take a fluoroquinolone antibiotic before a biopsy to prevent an infection. But its use can lead to bacteria developing resistance to antibiotics.
Infections after a needle biopsy may stem from bacteria migrating from the rectum — where the needle is inserted — to the prostate. And bacteria in urine may contribute to an infection.
Pennsylvania State University researchers wanted to know if it’s worth doing a urine test on men with no prostate cancer symptoms who are scheduled for a needle biopsy.
They collected urine from 150 men with no symptoms 14 days before their biopsy.
Six had levels of bacteria that could lead to infections. Three had Escherichia coli, one Klebsiella, and two a mixture of bacteria. Only two had levels of bacteria high enough to constitute urinary tract infections — one of those with E. coli and the one with Klebsiella. None had been treated for these bacteria.
All 150 patients received the fluoroquinolone ciprofloxacin the night before and on the morning of the biopsy.
Researchers collected urine samples from them just before the biopsy. The six who had had bacteria levels that could lead to an infection had less bacteria after taking the antibiotic. The other 144 continued to have low levels of bacteria that could lead to an infection.
After the biopsy, four men developed an infection. Two had sepsis and two a urinary tract infection, all caused by E. coli resistant to floroquinolone antibiotics. The four did not include any of the six patients whose bacteria levels were high before their biopsy.
Overall, the study suggested that relatively high levels of bacteria in urine before a biopsy do not increase the risk of a man developing an infection after the biopsy. In fact, “our data strongly advise against checking or treating asymptomatic men with bacteriuria before biopsy, as this may contribute to further development of antibiotic resistance in these patients,” the researchers wrote. The tests should be used instead with men showing possible prostate cancer symptoms, they said.
As for the reduction in bacteria levels with fluoroquinolones, the researchers wrote that “this class of antibiotic has great efficacy in urine and prostate tissue. It is possible that the single dose received by patients in this study was sufficient for eradication of urinary bacteria.”