Activity of an antimicrobial hydrocephalus shunt catheter against Propionibacterium acnes

Area of Science:

• Medical Microbiology
• Biomaterials Science
• Neurosurgery

Background:

• Shunt infection is a significant complication in approximately 10% of neurosurgical procedures.
• Propionibacterium acnes (P. acnes), an anaerobic skin bacterium, is an emerging pathogen responsible for up to 14% of shunt infections.
• Current prophylactic antibiotics have poor cerebrospinal fluid penetration, limiting their effectiveness against P. acnes shunt infections.

Purpose of the Study:

• To evaluate the efficacy of antimicrobial shunts against P. acnes, a common cause of shunt infections.
• To determine if antimicrobial shunts develop resistance to P. acnes with prolonged exposure to high bacterial loads.
• To assess the duration of antimicrobial activity and resistance to colonization under simulated in vivo conditions.

Main Methods:

• Three evaluation methods were employed: assessment of resistance to high inocula over time, determination of time-kill kinetics for attached bacteria, and evaluation of activity under constant flow with repeated challenges.
• The study simulated clinical conditions to determine the predictive value of antimicrobial catheter performance against P. acnes.

Main Results:

• No resistance to P. acnes emerged even after 70 days of repeated exposure to high bacterial inocula.
• Antimicrobial shunts required 96 hours to kill all attached P. acnes, which is twice as long as for staphylococci.
• Under constant flow and repeated challenges, antimicrobial catheters successfully resisted P. acnes colonization for 56 days.

Conclusions:

• Antimicrobial shunts demonstrate sustained activity against P. acnes, suggesting they can prevent colonization.
• The study indicates that antimicrobial shunts are a promising strategy to combat P. acnes-related hydrocephalus shunt infections.
• These findings support the clinical utility of antimicrobial shunts in reducing shunt infection rates caused by P. acnes.