Infections in CSF Shunts and External Ventricular Drainage

Infection in those with hydrocephalus shunts or external drains (EVDs) can cause serious central nervous system damage with lasting sequelae. The infections usually involve bacterial colonisation and biofilm formation in the catheters. The nature and sources of pathogens and preventive measures are discussed. The risks of infection in shunts and EVDs is different. Infection in shunts is almost always initiated at their insertion or revision (exceptions are described). In contrast, in EVDs, the risk of infection persists throughout their use. The pathogen profile is also different. These factors are important considerations when planning preventive measures. Newer strategies such as antimicrobial catheters are discussed. Diagnosis of EVD infections in an already ill patient is difficult but guidelines can be useful. Treatment of the shunt and EVD infections are also addressed, with reference to modes and routes of antibiotic administration

Molecular Pathogenesis and Clinical Impact of Biofilms in Surgery

Biofilms are responsible for chronic persistent infections and are a major problem in implant surgery. The microbial pathogenesis, treatment and prevention of biofilm infections is reviewed

Small-colony variant of Staphylococcus lugdunensis in prosthetic joint infection

Prosthetic joint infection is usually caused by staphylococci. Among the coagulase-negative staphylococci, Staphylococcus lugdunensis is important because it behaves as a pathogen similar to S aureus. It also develops biofilms, and the biofilm phenotype can appear as small-colony variants. Although genetically indistinguishable, they differ in size and antibiotic susceptibility from the parent strain and are responsible for chronic persistent infection and failure of antibiotic treatment. They can also lead to misinterpretation of results. The patient reported here underwent total knee replacement and 2 years later presented with prosthetic joint infection. Tissue samples and prosthesis taken at revision grew S lugdunensis, the majority of which were small-colony variants. Recommendations are made for their detection and identification

Infections in Intracranial Pressure Management: Impact of New Technologies on Infection Rates

It is now recognised that infections in CSF shunts and external ventricular drains (EVDs) are biofilm infections, and the scientific basis of these infections is better understood. Infection rates in shunts have now fallen but remain unacceptably high. There is an increase in infections due to multi-drug-resistant bacteria in EVDs. Reliance on antimicrobial prophylaxis has potential lifethreatening consequences and safer more effective measures are available. These consist of well-founded “bundles” or surgical protocols that have been shown to reduce infection by application of well known but not universally applied principles. New developments in antimicrobial technology have now been shown to be clinically effective and have reduced healthcare costs. The reduction in antibiotic use has led to fewer adverse effects. Problems with multidrug resistance in EVD infections remain and technology to address these has been developed but is not yet clinically available

Does release of antimicrobial agents from impregnated external ventricular drainage catheters affect the diagnosis of ventriculitis?

OBJECT 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