A study just published in the April issue of the Journal of Urology appears to show clearly that “targeted” antimicrobial prophylaxis can significantly reduce the risk of infections associated with transrectal ultrasound (TRUS)-guided biopies for risk of prostate cancer.
Taylor et al. report data from a study in which they used microbial culture results from rectal swabs to determine the most appropriate prophylactic antibiotic to use in individual men scheduled for prostate biopsy. It is current standard practice for men to be given a short course of ciprofloxacin (a fluoroquinolone antibiotic) prior to TRUS-guided biopsy unless the patient is known to be allergic to fluoroquinolone therapy. However, as an alternative strategy. Taylor and her colleagues set out to assess risk of patients to certain types of infection prior to TRUS-guided biopsy and to customize antibiotic prophylaxis to minimize individual risk.
The study was carried out on patients between July 2010 and March 2011. The authors studied the differences in infectious complications among men who received targeted vs standard empirical ciprofloxacin prophylaxis prior to TRUS-guided prostate biopsy. Patients from whom rectal swabs were taken then had cultures grown on selective media containing ciprofloxacin to identify the presence of fluoroquinolone-resistant bacteria. Those patients shown to have fluoroquinolone-susceptible organisms received standard ciprofloxacin prophylaxis; patients shown to harbor fluoroquinolone-resistant organisms were given directed antimicrobial prophylaxis specific to the organisms identified. All men having infectious complications within 30 days after TRUS-guided prostate biopsy were identified through careful monitoring of their electronic medical record.
Here are the key results reported by Taylor et al.:
- 457 men underwent TRUS-guided prostate biopsy.
- 112/457 men (24.5 percent) were given a rectal swab.
- 345/457 men (75.5 percent) received no rectal swab.
- 22/112 men (19.6 percent) who had rectal swabs were found to harbor fluoroquinolone-resistant organisms.
- There were no infectious complications among the 112 men who received targeted antimicrobial prophylaxis.
- There were 9 cases of infectious complications (including 1 case of sepsis) among the 345 men who received empirical ciprofloxacin therapy.
- Fluoroquinolone-resistant organisms caused 7/9 these infections in the men treated with empiric ciprofloxacin.
- The total cost of managing infectious complications in patients in the empirical group was $13,219.
- The calculated cost of targeted vs empirical prophylaxis per 100 men undergoing TRUS-guided prostate biopsy was $1,346 vs $5,598, respectively.
- Targeted prophylaxis yielded an estimated cost savings of $4,499 per post-TRUS-guided prostate biopsy infectious complication averted.
- An estimated 38 men would need to be given a rectal swab before TRUS-guided prostate biopsy to prevent 1 infectious complication
The authors conclude that, “Targeted antimicrobial prophylaxis was associated with a notable decrease in the incidence of infectious complications after transrectal ultrasound guided prostate biopsy caused by fluoroquinolone resistant organisms as well as a decrease in the overall cost of care.”
This paper appears to suggest an important new standard of care in the prevention of infections associated with TRUS-guided biopsy. While targeted antibiotic therapy will never be able to guarantee elimination of all risk of antibiotic infections associated with TRUS-guided prostate biopsies, the current study shows a reduction in risk from 9/345 (2.6 percent) to 0/112 (0 percent).
Rectal swabs can be taken at the time of pre-biopsy examination, so no additional office visit is required for such swabs to be taken. Appropriate prophylactic antibiotic therapy can then be customized to meet the need of specific patients based on the presence of fluoroquinolone-resistant antibiotics evident on culture.