LAUSR

To the Editor: This is the first prospective study to examine the use of intravesical gentamicin for treatment of recurrent urinary tract infections (UTIs), and the authors should be commended. Although the article provides some interesting conclusions, we would like to highlight the following comments regarding the study findings. In the title and abstract the authors state that the study population consists of patients with recurrent UTI caused by multidrug resistant organisms. However, on reading the Results section it becomes apparent that only 78% of patients had a history of multidrug resistant UTI. Therefore, it seems that the study was not performed with a well-defined cohort. Patients were included in this series based on their self-reported recollection of UTI frequency during the 6 months preceding trial entry. Furthermore, not all UTIs were culture proven. This self-reported frequency of UTI was later used as the comparative group on which the study findings are based. We question the accuracy and validity of the study conclusions, particularly considering the significant recall bias associated with this method of data collection. There are several inconsistencies in the presentation of the study results. The authors initially state that 87% of patients were treated according to the 24-week therapeutic protocol. However, elsewhere it is stated that 63% of patients continued to receive intravesical gentamicin “off protocol,” 25% received treatment for more than 28 weeks and 32% restarted gentamicin instillations during followup. Clarification of these discrepancies would greatly solidify the conclusions of the study. A limitation of this series is that the tolerability of intravesical gentamicin was not evaluated in a more rigorous fashion. The authors state that the treatment was well tolerated. This was inferred from high reported satisfaction rates when graded on a scale of 0 to 10. Yet 48% of patients underwent followup cystoscopy. The indication for cystoscopy is not clarified, although one must assume it was to investigate symptoms that may or may not have been exacerbated by intravesical treatment. One concern regarding the use of intravesical gentamicin is the risk of systemic absorption. The authors state that no patient had a detectable serum gentamicin level. However, in table 3 in the article only 62 patients are reported to have no detectable serum gentamicin level. Thus, 1 patient is unaccounted for, and this statement remains questionable. The authors also state that there was no increase in gentamicin resistance, although 9 patients had gentamicin resistant cultures recorded during the study period. Only 3 of these patients had a known history of gentamicin resistance. Again, without further clarification this statement appears inaccurate. In summary, this study appears to identify a role for the use of intravesical gentamicin in patients with recurrent UTI caused by multidrug resistant organisms. However, we believe that the main conclusions of this study are not fully supported by the results described. Further investigation using more accurately designed comparison groups is required to evaluate the true efficacy, tolerability and safety of this treatment.