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Does release of antimicrobial agents from impregnated external ventricular drainage catheters affect the diagnosis of
Roger Bayston1, Waheed Ashraf1, Catherine Ortori2
1Biomaterials-Related Infection Group, School of Medicine, and.
Objective:
Recently concern has arisen over the effect of released antimicrobial agents from antibiotic-impregnated external ventricular drainage (EVD) catheters on the reliability of CSF culture for diagnosis of ventriculitis. The authors designed a laboratory study to investigate this possibility, and to determine whether there was also a risk of loss of bacterial viability when CSF samples were delayed in transport to the laboratory.
Methods:
Three types of commercially available antibiotic-impregnated EVD catheters were perfused with a suspension of bacteria (Staphylococcus epidermidis) over 21 days. Samples were analyzed for bacterial viability and for concentrations of antibiotics released from the catheters. The authors also investigated the effect on bacterial viability in samples stored at 18°C and 4°C to simulate delay in CSF samples reaching the laboratory for analysis.
Results:
Bacterial viability was significantly reduced in all 3 catheter types when sampled on Day 1, but this effect was not observed in later samples. The results were reflected in stored samples, with significant loss of viability in Day 1 samples but with little further loss of viable bacteria in samples obtained after this time point. All samples stored for 18 hours showed significant loss of viable bacteria.
Conclusions:
While there were differences between the catheters, only samples taken on Day 1 showed a significant reduction in the numbers of viable bacteria after passing through the catheters. This reduction coincided with higher concentrations of antimicrobial agents in the first few hours after perfusion began. Similarly, bacterial viability declined significantly after storage of Day 1 samples, but only slightly in samples obtained thereafter. The results indicate that drugs released from these antimicrobial catheters are unlikely to affect the diagnosis of ventriculitis, as sampling for this purpose is not usually conducted in the first 24 hours of EVD.
Insights
Antimicrobial agents from external ventricular drainage (EVD) catheters do not affect cerebrospinal fluid (CSF) culture results for ventriculitis diagnosis. Bacterial viability is only reduced in early samples, not typically used for diagnosis.
Area of Science:
- Neuroscience
- Infectious Diseases
- Medical Devices
Background:
- Antibiotic-impregnated external ventricular drainage (EVD) catheters are used to prevent infections.
- Concerns exist that antimicrobial agents released from EVD catheters may interfere with cerebrospinal fluid (CSF) cultures.
- The impact of delayed CSF sample transport on bacterial viability also needs consideration.
Purpose of the Study:
- To investigate the effect of antimicrobial agents from EVD catheters on CSF culture reliability.
- To determine if delayed CSF sample transport affects bacterial viability.
Main Methods:
- Three types of antibiotic-impregnated EVD catheters were perfused with Staphylococcus epidermidis suspension for 21 days.
- Bacterial viability and antibiotic concentrations in samples were analyzed.
- The effect of storage at 18°C and 4°C on bacterial viability was assessed to simulate transport delays.
Main Results:
- Bacterial viability was significantly reduced in Day 1 samples from all catheter types.
- This reduction in viability was not observed in later samples.
- Stored Day 1 samples showed significant loss of viable bacteria, while later samples showed minimal loss.
Conclusions:
- The release of antimicrobial agents from EVD catheters minimally impacts bacterial viability in samples taken after Day 1.
- Delayed transport of CSF samples primarily affects viability in early samples.
- These findings suggest that antimicrobial EVD catheters are unlikely to compromise ventriculitis diagnosis through CSF culture.
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