The continuing rise in the incidence of Clostridium difficile infection is a cause for concern, with implications for patients and health care systems. Laboratory diagnosis largely relies on rapid toxin detection kits, although assays detecting alternative targets, including glutamate dehydrogenase (GDH) and toxin genes, are now available. Six hundred routine diagnostic diarrheal samples were tested prospectively using nine commercial toxin detection assays, cytotoxin assay (CYT), and cytotoxigenic culture (CYTGC) and retrospectively using a GDH detection assay and PCR for the toxin B gene. The mean sensitivity and specificity for toxin detection assays were 82.8% (range, 66.7 to 91.7%) and 95.4% (range, 90.9 to 98.8%), respectively, in comparison with CYT and 75.0% (range, 60.0 to 86.4%) and 96.1% (91.4 to 99.4%), respectively, in comparison with CYTGC. The sensitivity and specificity of the GDH assay were 90.1% and 92.9%, respectively, compared to CYT and 87.6% and 94.3%, respectively, compared to CYTGC. The PCR assay had the highest sensitivity of all the tests in comparison with CYT (92.2%) and CYTGC (88.5%), and the specificities of the PCR assay were 94.0% and 95.4% compared to CYT and CYTGC, respectively. All kits had low positive predictive values (range, 48.6 to 86.8%) compared with CYT, assuming a positive sample prevalence of 10% (representing the hospital setting), which compromises the clinical utility of single tests for the laboratory diagnosis of C. difficile infection. The optimum rapid single test was PCR for toxin B gene, as this had the highest negative predictive value. Diagnostic algorithms that optimize test combinations for the laboratory diagnosis of C. difficile infection need to be defined.

Antimicrobial lock treatment using 40 mg/mL(-1) of tetrasodium EDTA for at least 21 hours could significantly reduce or potentially eradicate CVC-associated biofilms of clinically relevant microorganisms.

This biofilm study was conducted to assess the in vitro activity of tetrasodium EDTA on catheters that had been routinely removed from hemodialysis patients at Leeds Teaching Hospitals Trust due to maturation of fistula. Catheters were screened by culture of through-catheter flush, and isolates were identified by standard methodologies; 20 isolates were found to be biofilm positive. Initial biofilm cell count levels averaged above 10 5 CFU/1-cm catheter section. Bacteria identified in the biofilms were gram-negative (1 isolate), gram-positive (11 isolates), or mixed species (8 isolates). After a 24-h lock, 40 mg of tetrasodium EDTA per ml was effective at eradicating the total biofilm viable count in almost all cases. The efficacy of tetrasodium EDTA as a catheter lock potentially shows that this agent could substantially reduce catheter-related infections and be used to treat patients with limited access.Catheters have become essential in the management of critical-care patients, yet the inside of a catheter is a major source of infection due to biofilms (1, 3). It has been found that at least 70% of all nosocomial bloodstream infections occur in patients with central venous catheters (7). Traditionally, catheters have been locked with normal saline or heparin solutions, sometimes in combination, to provide anticoagulant activity. Normal saline is generally used to lock short-term peripheral intravenous catheters, but saline has no anticoagulant or antimicrobial activity. Heparin solutions are generally used to lock vascular catheters. Heparin has anticoagulant activity, but it does not function as an antimicrobial and therefore does not provide protection from catheter-related infections. Recently, antibiotic lock solutions, with or without an anticoagulant (such as vancomycin-heparin), have been used for the prevention and management of catheter-related bacteremia (2,8,15). However, there are concerns, particularly with the use of a vancomycin flush solution, because of the potential for the development of resistant organisms (5, 9).EDTA is a calcium and iron chelator with anticoagulant activity. However, as a disodium salt it has been documented to have limited antistaphylococcal and anti-Candida activities (6,12,13). In contrast to this was a study by Raad et al., who demonstrated that minocycline and EDTA have highly synergistic activities in the decontamination of catheter surfaces when they are combined in a solution (10). It was found in that study that minocycline-EDTA was active against staphylococci, gram-negative bacilli, and Candida organisms that colonize polymers. This suggests a possible role of EDTA in catheter lock procedures.We undertook the present study by using in vivo renal lines in an in vitro technique to test the efficacy of tetrasodium EDTA on catheters removed from patients in order to determine its potential as a catheter lock solution to treat preformed biofilms and, ultimately, catheter-related infections. MATERIALS AND METHODSExperimental design. The study was conducted at the Le...

All three techniques had relatively high sensitivity. However, inability to obtain samples via central venous catheters is a major drawback of the differential time to positivity and quantitative blood culture approaches. Differential time to positivity is simple to perform and has high specificity and therefore could be used as a first line approach, with the endoluminal brush reserved for cases where blood cannot be obtained. All lumens of multiple-lumen central venous catheters must be sampled to ensure maximal sensitivity.