title: Does release of antimicrobial agents from impregnated external ventricular drainage catheters affect the diagnosis of ventriculitis?
abstract: 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.
authors.affiliation: Biomaterials-Related Infection Group, School of Medicine, and.
authors.forename: Roger
authors.initials: R
authors.lastname: Bayston
authors.affiliation: Biomaterials-Related Infection Group, School of Medicine, and.
authors.forename: Waheed
authors.initials: W
authors.lastname: Ashraf
authors.affiliation: School of Pharmacy, University of Nottingham, United Kingdom.
authors.forename: Catherine
authors.initials: C
authors.lastname: Ortori
mesh_terms: D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000494:pharmacology; D055499:Catheter-Related Infections / Q000517:prevention & control; D057785:Catheters; D002552:Cerebral Ventricles / Q000473:pathology / Q000601:surgery*; D058565:Cerebral Ventriculitis / Q000175:diagnosis*; D002557:Cerebrospinal Fluid Shunts; D004322:Drainage; D006801:Humans; D008826:Microbial Sensitivity Tests; D013212:Staphylococcus epidermidis / Q000187:drug effects; D013696:Temperature
chemical_list: D000890:Anti-Infective Agents
keywords: EVD = external ventricular drainage; HPLC = high performance liquid chromatography; LC-MS = liquid chromatography-mass spectrometry; MIC = minimum inhibitory concentration; antimicrobial catheter; external ventricular drainage; hydrocephalus; infection; ventriculitis