SEARCH

SEARCH BY CITATION

Keywords:

  • onabotulinumtoxin A;
  • abobotulinumtoxin A;
  • agar diffusion assay;
  • microdilution assay;
  • minimum inhibitory concentration;
  • antimicrobial effect

Study Type – Therapy (case series)

Level of Evidence 4

What's known on the subject? and What does the study add?

Several studies describe a reduction of symptomatic urinary tract infections in patients with neurogenic detrusor overactivity after intradetrusor injections of botulinum neurotoxin A (BoNT/A). It was, however, unclear if a direct antibacterial effect of BoNT/A plays a role in this clinical observation.

This is the first study to investigate a potential antibacterial effect of two frequently used BoNT/A formulations (i.e. Botox® and Dysport®), providing evidence that BoNT/A does not exert an antibacterial effect on lower urinary tract pathogens.

OBJECTIVE

  • • 
    To determine a potential direct antimicrobial effect of botulinum neurotoxin type A (BoNT/A).

MATERIALS AND METHODS

  • • 
    A prospective study was carried out using onabotulinumtoxin A (Botox®) and abobotulinumtoxin A (Dypsort®) in agar diffusion and broth microdilution assays with various clinical urinary tract isolates (Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, Acinetobacter baumannii, Citrobacter freundii, Klebsiella oxytoca and Bacillus subtilis).
  • • 
    Inhibition zones (mm) of bacteria around a disc containing 20 µL saline with 4 IU of Botox® were measured in the agar diffusion assay.
  • • 
    Minimal inhibitory concentrations (MICs, IU/mL) of both toxins for all bacteria were determined in the broth microdilution assay after overnight incubation at 35 °C.

RESULTS

  • • 
    There was no inhibition zone in the agar diffusion assays with any bacterial strain.
  • • 
    The microdilution test using Botox® and Dysport® showed bacterial growth in all dilutions, i.e. MICs > 20 and >100 IU/mL for Botox® and Dysport®, respectively.

CONCLUSIONS

  • • 
    BoNT/A has no direct antimicrobial effect.
  • • 
    The reduced frequency of symptomatic urinary tract infections (sUTIs) in patients with neurogenic detrusor overactivity (NDO) after BoNT/A intradetrusor injections seems to be caused by different indirect mechanisms, which are still not completely understood.