Are Antimicrobial-Impregnated Catheters Effective? Replace the Water and Grab Your Washcloth, Because We Have a Baby to Wash

Investigation of biofilm formation on a charged intravenous catheter relative to that on a similar but uncharged catheter

Catheter-related blood stream infections increase morbidity, mortality, and costs. This study investigated whether Certofix^® protect antimicrobial catheters carry a surface charge and whether this inhibits biofilm formation. The capacitance of the catheter surfaces was measured and, to determine if the catheters released ions, distilled water was passed through and current measured as a function of voltage. With probes touching the inner and outer surfaces, capacitance was not voltage-dependent, indicating surfaces were uncharged or carried a similar charge. When one probe penetrated the catheter wall, capacitance was weakly voltage-dependent, indicating the presence of a surface charge. Standard and charged catheters were also exposed to phosphate buffered saline as controls or 2×10⁶ colony forming units/mL (in phosphate buffered saline) of six different microorganisms for 60 or 120 minutes. When the growth of detached bacteria was measured, biofilm formation was significantly reduced, (P<0.05), for charged catheters for all organisms.

Robustness analysis of culturing perturbations on Escherichia coli colony biofilm beta-lactam and aminoglycoside antibiotic tolerance

Background

Biofilms are ubiquitous. For instance, the majority of medical infections are thought to involve biofilms. However even after decades of investigation, the in vivo efficacy of many antimicrobial strategies is still debated suggesting there is a need for better understanding of biofilm antimicrobial tolerances. The current study's goal is to characterize the robustness of biofilm antibiotic tolerance to medically and industrially relevant culturing perturbations. By definition, robust systems will return similar, predictable responses when perturbed while non-robust systems will return very different and potentially unpredictable responses. The predictability of an antibiotic tolerance response is essential to developing, testing, and employing antimicrobial strategies.

Results

The antibiotic tolerance of Escherichia coli colony biofilms was tested against beta-lactam and aminoglycoside class antibiotics. Control scenario tolerances were compared to tolerances under culturing perturbations including 1) different nutritional environments 2) different temperatures 3) interruption of cellular quorum sensing and 4) different biofilm culture ages. Here, antibiotic tolerance was defined in terms of culturable biofilm cells recovered after a twenty four hour antibiotic treatment.

Colony biofilm antibiotic tolerances were not robust to perturbations. Altering basic culturing parameters like nutritional environment or temperature resulted in very different, non-intuitive antibiotic tolerance responses. Some minor perturbations like increasing the glucose concentration from 0.1 to 1 g/L caused a ten million fold difference in culturable cells over a twenty four hour antibiotic treatment.

Conclusions

The current study presents a basis for robustness analysis of biofilm antibiotic tolerance. Biofilm antibiotic tolerance can vary in unpredictable manners based on modest changes in culturing conditions. Common antimicrobial testing methods, which only consider a single culturing condition, are not desirable since slight culturing variations can lead to very different outcomes. The presented data suggest it is essential to test antimicrobial strategies over a range of culturing perturbations relevant to the targeted application. In addition, the highly dynamic antibiotic tolerance responses observed here may explain why some current antimicrobial strategies occasionally fail.

Approach to the febrile patient in the ICU

Fever is a normal adaptive brain response to infectious and noninfectious causes involving a cytokine-mediated response, the generation of acute phase reactants, and the activation of numerous physiologic, endocrinologic and immunologic systems. Ninety percent of patients with severe sepsis in the intensive care unit (ICU) will experience fever during their hospitalization, while the half of the new detected febrile episodes are of noninfectious origin. In the ICU, fever should be treated in cardiorespiratory and neurosurgical patients and in those in whom temperature exceeds 40 degrees C (104 degrees F). Antipyretic therapy must be justified regardless of the metabolic cost (if fever exceeds its physiologic benefit), the result (if the symptomatic relief adversely affects the course of the febrile illness) and the side effects.

Prevention of catheter-related bloodstream infections

CRBSIs are expensive, prevalent, and often fatal complications. In the past few years, several preventive interventions have been applied with excellent results toward decreasing CRBSIs. Studies show that most CRBSIs are preventable; therefore, health care organizations should strive to substantially reduce if not eliminate them. In addition to being a measure of quality of care, reducing infections will soon be a bottom-line issue, given that the Centers for Medicare and Medicaid Services announced its decision to cease paying hospitals from October 2008 for some care necessitated by "preventable complications", including CRBSIs. Therefore, health care facilities that do not make the necessary adjustments to improve the quality of their patient care and avoid harm may be economically penalized. This article reviews the available evidence on and possible barriers to the widespread use of preventive strategies. The health care community has struggled to build a culture that can eliminate the barriers obstructing high-quality care. These new approaches must facilitate collaboration among caregivers. During the past few years, much effort has been dedicated to researching causes for inadequate patient care and executing interventions to improve processes of care; only now are projects beginning to focus on evaluating whether patients are safer. This article discusses the prevention of CRBSIs and shows that substantial reductions in the rate of these infections are possible. It is no longer acceptable for health care organizations to have the goal of being at the CDC mean for rate of infections; they should strive to substantially reduce or even eliminate them. Patients deserve no less.

Central venous catheterization: a prospective, randomized, double-blind study

Central venous catheters (CVCs) are extensively used worldwide. Mechanical, infectious and thrombotic complications are well described with their use and may be associated with prolonged hospitalization, increased medical costs and mortality. CVCs account for an estimated 90% of all catheter-related bloodstream infections (CRBSI) and a host of risk factors for CVC-related infections have been documented. The duration of use of CVCs remains controversial and the length of time such devices can safely be left in place has not been fully and objectively addressed in the critically ill patient. Antimicrobial-impregnated catheters have been introduced in an attempt to limit catheter-related infection (CRI) and increase the time that CVCs can safely be left in situ. Recent meta-analyses concluded that antimicrobial-impregnated CVCs appear to be effective in reducing CRI. The authors conducted a prospective, randomized, double-blind study at Johannesburg Hospital over a 4-year period. The study entailed a comparison of standard triple-lumen versus antimicrobial impregnated CVCs on the rate of CRI. Our aim was to determine whether we could safely increase the duration of catheter insertion time from our standard practice of seven days to 14 days, to assess the influence of the antimicrobial impregnated catheter on the incidence of CRI, and to elucidate the epidemiology and risks of CRI. One hundred and eighteen critically ill patients were included in the study which spanned 34 951.5 catheter hours (3.99 catheter years). It was found that antimicrobial catheters did not provide any significant benefit over standard catheters, which the authors feel can safely be left in place for up to 14 days with appropriate infection control measures. The most common source of CRI was the skin. The administration of parenteral nutrition and the site of catheter insertion (internal jugular vein vs subclavian vein) were not noted to be risk factors for CRI. There was no clinical evidence of thrombotic complication in either of the study groups. This study offers direction for the use of CVCs in critically ill patients and addresses many of the controversies that exist.

A systematic review comparing the relative effectiveness of antimicrobial-coated catheters in intensive care units

BACKGROUND

Bloodstream infection related to a central venous catheter is a substantial clinical and economic problem. To develop policy for managing the risks of these infections, all available evidence for prevention strategies should be synthesized and understood.

METHODS

We evaluate evidence (1985-2006) for short-term antimicrobial-coated central venous catheters in lowering rates of catheter-related bloodstream infection (CRBSI) in the adult intensive care unit. Evidence was appraised for inclusion against predefined criteria. Data extraction was by 2 independent reviewers. Thirty-four studies were included in the review. Antiseptic, antibiotic, and heparin-coated catheters were compared with uncoated catheters and one another. Metaanalysis was used to generate summary relative risks for CRBSI and catheter colonization by antimicrobial coating.

RESULTS

Externally impregnated chlorhexidine/silver sulfadiazine catheters reduce risk of CRBSI relative to uncoated catheters (RR, 0.66; 95% CI: 0.47-0.93). Minocycline and rifampicin-coated catheters are significantly more effective relative to CHG/SSD catheters (RR, 0.12; 95% CI: 0.02-0.67). The new generation chlorhexidine/silver sulfadiazine catheters and silver, platinum, and carbon-coated catheters showed nonsignificant reductions in risk of CRBSI compared with uncoated catheters.

CONCLUSION

Two decades of evidence describe the effectiveness of antimicrobial catheters in preventing CRBSI and provide useful information about which catheters are most effective. Questions surrounding their routine use will require supplementation of this trial evidence with information from more diverse sources.

Economic evaluation and catheter-related bloodstream infections

Catheter-related bloodstream infections are a serious problem. Many interventions reduce risk, and some have been evaluated in cost-effectiveness studies. We review the usefulness and quality of these economic studies. Evidence is incomplete, and data required to inform a coherent policy are missing. The cost-effectiveness studies are characterized by a lack of transparency, short time-horizons, and narrow economic perspectives. Data quality is low for some important model parameters. Authors of future economic evaluations should aim to model the complete policy and not just single interventions. They should be rigorous in developing the structure of the economic model, include all relevant economic outcomes, use a systematic approach for selecting data sources for model parameters, and propagate the effect of uncertainty in model parameters on conclusions. This will inform future data collection and improve our understanding of the economics of preventing these infections.

Comparison of silver-impregnated with standard multi-lumen central venous catheters in critically ill patients*

OBJECTIVES

To evaluate a new silver-impregnated multi-lumen central venous catheter for reducing catheter-related colonization in intensive care patients.

DESIGN

Multicenter, prospective, randomized, controlled clinical study.

SETTING

Ten adult intensive care units (multidisciplinary, medical and surgical, university and nonuniversity hospitals) in eight institutions.

PATIENTS

A total of 577 patients who required 617 multi-lumen central venous catheters between November 2002 and April 2004 were studied.

INTERVENTIONS

Intensive care adult patients requiring multi-lumen central venous catheters expected to remain in place for >or=3 days were randomly assigned to undergo insertion of silver-impregnated catheters (silver group) or standard catheters (standard group). Catheter colonization was defined as the growth of >or=1,000 colony-forming units in culture of the intravascular tip of the catheter by the vortexing method. Diagnosis of catheter-related infection was performed by an independent and blinded expert committee.

RESULTS

A total of 320 catheters were studied in the silver group and 297 in the standard group. Characteristics of the patients, insertion site, duration of catheterization (median, 11 vs. 10 days), and other risk factors for infection were similar in the two groups. Colonization of the catheter occurred in 47 (14.7%) vs. 36 (12.1%) catheters in the silver and the standard groups (p = .35), for an incidence of 11.2 and 9.4 per 1,000 catheter days, respectively. Catheter-related bloodstream infection was recorded in eight (2.5%) vs. eight (2.7%) catheters in the silver and the standard groups (p = .88), for an incidence of 1.9 and 2.1 per 1,000 catheter days, respectively.

CONCLUSION

The use of silver-impregnated multi-lumen catheters in adult intensive care patients is not associated with a lower rate of colonization than the use of standard multi-lumen catheters.

Antimicrobial impregnated catheters in the prevention of catheter-related bloodstream infection in hospitalized patients

Catheter-related bloodstream infections have a significant impact on increasing health care costs and morbidity and mortality in hospitalized patients. Many technologies have been created in an attempt to decrease the incidence of catheter-related bloodstream infection. One of these is the impregnation of central venous catheters with antiseptics (e.g., chlorhexidine and silver sulfadiazine) or antibiotics (e.g., minocycline and rifampin). While studies evaluating the efficacy of impregnated catheters have been conducted, the data are limited and their use remains variable across institutions. This paper will discuss catheter-related factors that predispose patients to catheter-related bloodstream infection, the types of antimicrobial-impregnated catheters in use today, studies evaluating their efficacy, and common concerns associated with the use of these catheters. Issues related to the cost-effectiveness of impregnated catheters and future directions for the prevention of catheter-related bloodstream infection will also be presented.

Rifampicin-impregnated central venous catheters: a meta-analysis of randomized controlled trials

BACKGROUND

The use of antimicrobial-impregnated central venous catheters (CVCs) for the prevention of CVC microbial colonization and catheter-related bloodstream infection (CRBSI) remains controversial.

METHODS

We performed a meta-analysis of randomized controlled trials (RCTs) evaluating CRBSI and colonization of CVCs impregnated with rifampicin-based antimicrobial combinations. Our main analysis compared the occurrence of CRBSI with rifampicin/minocycline-impregnated CVCs with that of non-rifampicin-impregnated CVCs. The PubMed and Cochrane Central Register of Controlled Trials databases were searched (until October 2006).

RESULTS

Eight RCTs were included in the analysis. The main analysis (seven RCTs) demonstrated that rifampicin/minocycline-impregnated CVCs were associated with fewer CRBSIs compared with catheters not impregnated with rifampicin/minocycline (OR 0.23, 95% CI 0.14-0.40). The same was true regarding colonization (OR 0.46, 95% CI 0.31-0.69). Further analysis, comparing rifampicin-based CVCs with non-rifampicin-impregnated CVCs, demonstrated superiority of rifampicin-based CVCs in reducing colonization (OR 0.38, 95% CI 0.24-0.62) and CRBSI (OR 0.24, 95% CI 0.14-0.40). Similar results, suggesting superiority of rifampicin/minocycline-impregnated CVCs, were noted in a subgroup analysis of colonization and CRBSIs in which rifampicin/minocycline-impregnated CVCs were compared with simple, non-tunnelled, non-antimicrobially impregnated CVCs, a subgroup analysis that was performed by excluding low quality RCTs, and a subgroup analysis for colonization comprising studies in which the sonication technique was used. No serious adverse events and no difference in mortality between the two treatment groups were reported. No clear conclusions can be made regarding the impact of the use of rifampicin/minocycline-impregnated CVCs on the development of antimicrobial resistance based on the available data.

CONCLUSIONS

The available evidence suggests that rifampicin/minocycline-impregnated CVCs are safe and effective in reducing the rate of catheter colonization and CRBSI. Further research should focus on the possible development of resistance and on pharmacoeconomic issues related to the use of rifampicin/minocycline-impregnated CVCs.

Use of catheters with the AgION antimicrobial system in kidney transplant recipients to reduce infection risk

Microbial blood infection represents a high risk for immuno-suppressed patients. Of all catheter-related infections in the bloodstream, 90% result from the use of central venous catheters, the main cause being microbial colonization at the catheter's insertion point or the catheter hub. Between January 2003 and December 2004, 102 patients received a renal transplant including 57 who received a triple-lumen central venous catheter (CVC) during the procedure. Two catheters were used: a standard polyurethane catheter placed in the jugular veina or the subclavian veina for group I, and polyurethane catheters with the AgION antimicrobial system always placed in the subclavian veina for group II. Care and maintenance of the CVCs was standardized in both groups. After catheter removal, the tips were analyzed microbiologically. Of 57 (43.9%) CVCs, 25 were found to be contaminated. In the first group 24 out of 41 CVCs (58.5%) showed bacterial growth, whereas in group II only one catheter (6.6%) had a biofilm. The most common contaminant (18 out of 25, 72%) was Staphylococcus epidermidis. In group II, two patients had positive blood cultures yet a microbiologically sterile CVC. None of the catheters with the AgION antimicrobial system had to be removed owing to local infection or intolerance. The continuous release of silver ions increases the protection against bacteria and fungi during the entire time of catheterization. Use of catheters with the AgION antimicrobial system lead to a marked reduction in catheter-associated infections of the bloodstream.

A prospective, randomized trial of rifampicin-minocycline-coated and silver-platinum-carbon-impregnated central venous catheters*

OBJECTIVE

Central venous catheters are the predominant cause of nosocomial bacteremia; however, the effectiveness of different antimicrobial central venous catheters remains uncertain. We compared the infection rate of silver-platinum-carbon (SPC)-impregnated catheters with rifampicin-minocycline (RM)-coated catheters.

DESIGN

A large, single-center, prospective randomized study.

SETTING

Twenty-two-bed adult general intensive care unit in a large tertiary metropolitan hospital in Brisbane, Australia (2000-2001).

PATIENTS

Consecutive series of all central venous catheterizations in intensive care unit patients.

INTERVENTIONS

Randomization, concealment, and blinding were carefully performed. Catheter insertion and care were performed according to published guidelines. Blood cultures were taken at central venous catheter removal, and catheter-tip cultures were performed by both roll-plate and sonication techniques. Pulsed field gel electrophoresis was used to establish shared clonal origin for matched isolates.

MEASUREMENTS AND MAIN RESULTS

Central venous catheter colonization and catheter-related bloodstream infection were determined with a blinded technique using the evaluation of the extensive microbiological and clinical data collected and a rigorous classification system. Six hundred forty-six central venous catheters (RM 319, SPC 327) were inserted, and 574 (89%) were microbiologically evaluable. Colonization rates were lower for the RM catheters than SPC catheters (25 of 280, 8.9%; 43 of 294, 14.6%; p=.039). A Kaplan-Meier analysis that included catheter time in situ did not quite achieve statistical significance (p=.055). Catheter-related bloodstream infection was infrequent for both catheter-types (RM 4, 1.4%; SPC 5, 1.7%).

CONCLUSIONS

The SPC catheter is a clinically effective antimicrobial catheter; however, the RM catheter had a lower colonization rate. Both catheter types had low rates of catheter-related bloodstream infection. These results indicate that future studies will require similar rigorous methodology and thousands of central venous catheters to demonstrate differences in catheter-related bloodstream infection rates.

Infection control, hospital epidemiology, and patient safety

Health care-acquired are a major risk for hospitalized children. Similar to adult patients, children are vulnerable to infections related to medical devices. Children also are at significant risk of nosocomial transmission of common pediatric viral illness, such as respiratory syncytial virus and varicella. In addition, pediatric patients have unique or incompletely developed immune system.

Drug/device combinations for local drug therapies and infection prophylaxis

Combination devices-those comprising drug releasing components together with functional prosthetic implants-represent a versatile, emerging clinical technology promising to provide functional improvements to implant devices in several classes. Landmark antimicrobial catheters and the drug-eluting stent have heralded the entrance, and significantly, routes to FDA approval, for these devices into clinical practice. This review describes recent strategies creating implantable combination devices. Most prominent are new combination devices representing current orthopedic and cardiovascular implants with new added capabilities from on-board or directly associated drug delivery systems are now under development. Wound coverings and implantable sensors will also benefit from this combination enhancement. Infection mitigation, a common problem with implantable devices, is a current primary focus. On-going progress in cell-based therapeutics, progenitor cell exploitation, growth factor delivery and advanced formulation strategies will provide a more general and versatile basis for advanced combination device strategies. These seek to improve tissue-device integration and functional tissue regeneration. Future combination devices might best be completely re-designed de novo to deliver multiple bioactive agents over several spatial and temporal scales to enhance prosthetic device function, instead of the current 'add-on' approach to existing implant device designs never originally intending to function in tandem with drug delivery systems.