SAN DIEGO—Urologists may need to re-examine the use of oral fluoroquinolones (FQ) as prophylaxis after transrectal ultrasound-guided (TRUS) biopsy of the prostate, according to study findings presented here at the annual meeting of the Infectious Diseases Society of America.


The study, conducted at Metro West Medical Center in Framingham, Mass., showed that the susceptibility of Escherichia coli to fluoroquinolones decreased from 100% in 1998 to 86% in 2006, said lead investigator Idriss El Koussaimi, MD, a third-year resident in internal medicine who conducted the study in conjunction with the center’s department of infectious diseases.

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Most U.S. urologists use oral FQ to decrease the risk of infection after TRUS biopsy even though there is no consensus on the best prophylactic strategy. Over the past 10 years, the widespread use of FQ for treating a host of infections has resulted in the development of substantial resistance. Dr. El Koussaimi said he and his colleagues recently observed an increase in serious bacteremias after prostate biopsy caused by antibiotic-resistant E. coli.


The researchers retrospectively reviewed all gram-negative bacteremias diagnosed in their community hospital from January 2005 through March 2006 in men aged 45-90 years. They also collected data on bacteremic patients who had recently undergone TRUS prostate biopsy.

Of 89 cases of gram-negative bacteremias diagnosed in older men during the study period, 13 (14.6%) were preceded by TRUS prostate biopsy. The mean age of the patients who were diagnosed with gram-negative bacteremias was 61 years (range 52-76 years). All 13 patients received prophylactic antibiotics before and after the TRUS biopsy. FQ were given to 11 of the 13 patients; two received trimethoprim-sulfamethoxazole because they had FQ allergies. 


All 13 patients had E. coli bacteremia. In 12 (92%), the infection was resistant to FQ, including 11 of the patients who received FQ prophylaxis and seven (54%) who were resistant to trimethoprim-sulfamethoxazole. Additionally, the investigators found gentamicin resistance in 38% of the isolates.


The time between the biopsy and the date of the first positive blood culture ranged from 1-7 days, with a mean interval of three days. Of the 13 men, 11 required hospitalization.  Although no deaths occurred, severe sepsis developed in two and an epidural abscess developed in one.

“It is not just the prophylaxis in this setting that is causing the resistance, but the overall overuse of quinolones for treating many infections, including pneumonias,” Dr. El Koussaimi told Renal & Urology News. “We are not sure what urologists should use but they may want to consider using another antibiotic because the prophylaxis strategy may need to be changed.”