‘One shunt fits all?’: a comparative laboratory study of antibiotic-impregnated shunt catheters with retrospective clinical correlation

Introduction Several antibiotic-impregnated shunt catheters are commercially available, but direct comparative data on their biochemical and physical characteristics remain limited. Previous observations from our single-centre neurosurgical unit suggested that nominally similar catheter types may be associated with different rates of otherwise unexplained abdominal pain. We therefore conducted a prospective comparative study to investigate potential biochemical and physical differences between commercially available antibiotic-impregnated shunt catheters. Methods Ares ® , Bactiseal ® and XABO ® catheters were compared for antibiotic content, rifampicin degradation products, elution characteristics and antimicrobial activity. Antibiotic elution was assessed during continuous saline perfusion at 20 mL/h and 37 °C over 8 weeks, while antimicrobial activity against Staphylococcus epidermidis was evaluated over 60 days. Catheter dimensions, elastic modulus and surface morphology were assessed using three-dimensional computed tomography, nanoindentation and scanning electron microscopy, respectively. An exploratory retrospective quality-improvement dataset from our single-centre unit was additionally analysed to compare the frequency of otherwise unexplained abdominal pain between catheter types. Results The three catheter systems showed product-specific differences in antibiotic content, rifampicin degradation profiles, elution characteristics, antimicrobial activity, dimensions, mechanical properties and surface morphology. XABO ® most closely matched the declared antibiotic concentrations and retained the greatest proportion of intact rifampicin, while Ares ® demonstrated the highest sustained clindamycin elution. All three catheters retained measurable activity against Staphylococcus epidermidis for 60 days, with XABO ® showing the largest numerical inhibition zones throughout. In the 395-patient retrospective clinical analysis, otherwise unexplained abdominal pain was recorded in 90/182 patients with Ares ® catheters (49.5%) compared with 12/108 patients with Bactiseal ® catheters (11.1%). After adjustment for age, sex, primary diagnosis, modified Rankin Scale score and activity level, Ares ® remained associated with greater odds of abdominal pain than Bactiseal ® (adjusted OR 6.89, 95% CI 2.58–18.43; p < 0.001). Conclusion Commercially available antibiotic-impregnated shunt catheters showed product-specific biochemical and physical variation, while catheter type was associated with different rates of otherwise unexplained abdominal pain in a retrospective single-centre analysis. These findings are hypothesis-generating and do not establish causality or clinical superiority. Prospective multicentre studies are required to determine whether catheter-specific properties translate into clinically meaningful differences and should influence individualised shunt selection.