The national burden of infections after prostate biopsy in England and Wales: a wake-up call for better prevention--authors' response

Abstract

Sir, We thank Balakrishnan and Smith for their interest in our paper and congratulate them for the results they have achieved with their approach to antimicrobial prophylaxis for transrectal ultrasound-guided needle biopsy. A risk-based stratification to decide on the choice of prophylaxis is a commendable approach. However, as with other risk-based strategies, it is possible that some patients may slip through the net for a variety of reasons; for instance, when the risk factors are unknown or have not been elicited by the urologist. Furthermore, if radiologists do the biopsies, as in our hospital, they would need to be informed of the suitable prophylaxis for each patient. It is for these practical reasons that we have not adopted a risk-based strategy in our hospital. Given the very low incidence of post-biopsy infections reported by Balakrishnan and Smith, we think it would be necessary to followup a larger cohort of patients to state confidently that the risk-based approach using temocillin prophylaxis is consistently effective. It would also be informative for them to compare their current rate of infections with the background rate before they started their riskbased strategy. Similarly, it would be useful to know the prevalence of ciprofloxacin resistance and extended-spectrum b-lactamases (ESBLs) in their local community. Finally, it would be useful to know the proportion of patients undergoing biopsy that needed temocillin prophylaxis based on this risk-based strategy. We have had good results by adding amikacin to ciprofloxacin prophylaxis since 2007. In a review of our practice in 2012 we continued to have a low rate of infection using this combination. Amikacin has the advantage of a long post-antibiotic effect, conferring an added benefit. Moreover, a high concentration of amikacin is found in prostatic tissue after one dose. Additionally, we believe it is unlikely that a single dose of amikacin will critically alter the intestinal flora or promote resistance. It is worth noting that we have had Pseudomonas spp. bacteraemia among our prostate biopsy patients in the past. Amikacin would clearly be more useful in such settings. In our local population in north-west London, 1% of Escherichia coli strains in urinary tract infections are resistant to amikacin compared with 7% resistant to temocillin, and 1% of ESBL strains are amikacin resistant whereas 4% are resistant to temocillin (G. Gopal Rao, unpublished laboratory data). Clearly, the field of antimicrobial prophylaxis for prostate biopsy is an evolving one and new strategies to make the procedure safer are needed and would be welcomed.