Bert Vorstman, MD,MS,FAAP,FRACS,FACS
Simple rectal swab cultures prior to prostate biopsy procedures can stop some infections found after the procedure due to drug-resistant Escherichia coli. Rhode Island Hospital researchers found that the cultures test for antibiotic-resistant E. Coli and the findings are used to direct the selection of antimicrobial prophylaxis used for the procedure.
For patients undergoing transrectal ultrasound (TRUS)-guided biopsies, Ciprofloxacin may not be the best prophylactic option to use for patients colonized with Ciprofloxacin- resistant E. coli.
“Aware of the increasing number of resistant strains of E. coli, our urologic physicians sought to decrease the number of post-biopsy infections and readmissions by conducting cultures on patient fecal samples to identify antibiotic-resistant strains before the biopsy is done, and the results were used to make the best antibiotic choice for prophylaxis,” said Leonard Mermel, D.O., medical director of the department of epidemiology and infection control at Rhode Island Hospital. “As effective as biopsies are for diagnosing cancer, they do carry some risk of infection.”
According to the Centers for Disease Control and Prevention, of nearly 1 million prostate biopsies conducted in the U.S. annually, 209,292 men were diagnosed with prostate cancer. Most post-biopsy infections are caused by E. coli and arise from direct inoculation of bacteria from the rectal mucosa in the urinary tract and surrounding area. The reported rates of post- biopsy infections range for 2 to 6 percent, and overall hospital readmissions have been reported as high as 6.3 percent.
Researchers assessed the incidence of fluoroquinolone resistance in E. Coli of adult patients undergoing prostate biopsy based on the study at Rhode Island Hospital. The researchers evaluated the effect of culture-directed prophylaxis on the risk of infectious complications after biopsy and found that 12.8 percent of the patients had pre-existing, drug-resistant E.coli on the rectal swab cultures. Additionally, they noted that there was a lower likelihood risk of
infectious complications for patients receiving prophylaxis based on pre-biopsy rectal swab cultures, but the differences did not reach statistical significance because of the study size.
Nevertheless, patients had longer hospitalizations for post-procedure infection (3 days versus 1.6 days) when they did not have the pre-biopsy rectal swab cultures done and they developed an infectious complication after the biopsy. While 40 percent required continued outpatient treatment with IV antibiotics for those infections, compared with the 16.6 percent of the group treated with culture-directed antibiotics.
“As men are increasingly opting for active surveillance of prostate cancer, infectious risks associated with prostate biopsy are becoming particularly relevant,” said Jessica Dai, M.D., a co-author who is now with the University of Washington. “We hypothesized that the incidence of infections would decline after instituting this new screening process, and they did. Not only did we see that, we also met our secondary aim of establishing the local incidence of fluoroquinolone-resistant and extended-spectrum beta-lactamase (ESBL)- producing bacteria in rectal swab cultures.”
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