Clinical evaluation of catheter-related fungemia and bacteremia

Central venous catheter (CVC) removal for patients of all ages with candidaemia

BACKGROUND

Candida bloodstream infections most often affect those already suffering serious, potentially life-threatening conditions and often cause significant morbidity and mortality. Most affected persons have a central venous catheter (CVC) in place. The best CVC management in these cases has been widely debated in recent years, while the incidence of candidaemia has markedly increased.

OBJECTIVES

The main purpose of this review is to examine the impact of removing versus retaining a CVC on mortality in adults and children with candidaemia who have a CVC in place.

SEARCH METHODS

We searched the following databases from inception to 3 December 2015: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid SP), EMBASE (Ovid SP), the Commonwealth Agricultural Bureau (CAB), Web of Science and the Cumulative Index to Nursing and Allied Health Literature (CINAHL). We searched for missed, unreported and ongoing trials in trial registries and in reference lists of excluded articles.

SELECTION CRITERIA

We searched for randomized controlled trials (RCTs) and quasi-RCTs involving adults and children with candidaemia and in which participants were randomized for removal of a CVC (the intervention under study), irrespective of publication status, date of publication, blinding status, outcomes published or language.However, two major factors make the conduct of RCTs in this population a difficult task: the large sample size required to document the impact of catheter removal in terms of overall mortality; and lack of economic interest from the industry in conducting such a trial.

DATA COLLECTION AND ANALYSIS

Our primary outcome measure was mortality. Several secondary outcome measures such as required time for clearance of blood cultures for Candida species, frequency of persistent candidaemia, complications, duration of mechanical ventilation and length of stay in the intensive care unit (ICU) and in the hospital were planned, as were various subgroup and sensitivity analyses, according to our protocol. We assessed papers and abstracts for eligibility and resolved disagreements by discussion. However, we were not able to include any RCTs or quasi-RCTS in this review and, as a result, have carried out no meta-analyses. However, we have chosen to provide a brief overview of excluded observational studies.

MAIN RESULTS

We found no RCT and thus no available data for evaluation of the primary outcome (mortality) nor secondary outcomes or adverse effects. Therefore, we conducted no statistical analysis.A total of 73 observational studies reported on various clinically relevant outcomes following catheter removal or catheter retention. Most of these excluded, observational studies reported a beneficial effect of catheter removal in patients with candidaemia. None of the observational studies reported results in favour of retaining a catheter. However, the observational studies were very heterogeneous with regards to population, pathogens and interventions. Furthermore, they suffered from confounding by indication and an overall high risk of bias. As a consequence, we are not able to provide recommendations or to draw firm conclusions because of the difficulties involved in interpreting the results of these observational studies (very low quality of evidence, GRADE - Grades of Recommendation, Assessment, Development and Evaluation Working Group).

AUTHORS' CONCLUSIONS

Despite indications from observational studies in favour of early catheter removal, we found no eligible RCTs or quasi-RCTs to support these practices and therefore could draw no firm conclusions. At this stage, RCTs have provided no evidence to support the benefit of early or late catheter removal for survival or other important outcomes among patients with candidaemia; no evidence with regards to assessment of harm or benefit with prompt central venous catheter removal and subsequent re-insertion of new catheters to continue treatment; and no evidence on optimal timing of insertion of a new central venous catheter.

Catheter-related vs. catheter-associated blood stream infections in the intensive care unit: incidence, microbiology, and implications

BACKGROUND

Catheter-associated blood stream infections (CA-BSI) and catheter-related blood stream infections (CR-BSIs) differ in the degree of proof required to show that the catheter is the cause of the infection. The U.S. Centers for Disease Control and Prevention (CDC) National Healthcare Safety Network (NHSN; formerly the National Nosocomial Infections Surveillance [NNIS] group) collects data regarding CA-BSI nationally. We hypothesized that there would be a significant difference in the rates reported according to the definition.

METHODS

Prospective surveillance of CA-BSI (defined as bacteremia with no extravascular source identified) is performed in all intensive care units (ICUs) at our institution and reported as the rate per 1,000 catheter-days. In January 2006, we initiated cultures of all catheter tips to evaluate for CR-BSI (defined as a catheter tip culture with >15 colony-forming units of the same microorganism(s) found in the blood culture) in the surgical, trauma-burn, and medical ICUs.

RESULTS

The CA-BSI rate across all ICUs for the 24-mo study period was 1.4/1,000 catheter-days. The CR-BSI rate was 0.4/1,000 catheter days, for a rate difference of 1.0 infections/1,000 catheter-days (p < 0.001 vs. CA-BSI). The pathogens identified in CA-BSI included many organisms that are not associated with catheter-related BSIs.

CONCLUSIONS

The CR-BSI rate is significantly lower than the CA-BSI rate. The organisms identified in CA-BSI surveillance often are not common in catheter-related infections. Reporting CR-BSI thus is a more accurate measure of complications of central venous catheter use, and this rate may be more sensitive to catheter-specific interventions designed to reduce rates of BSI in the ICU.

Pharmacodynamic assessment of vancomycin–rifampicin combination against methicillin resistant Staphylococcus aureus biofilm: a parametric response surface analysis†

Objectives

A combination of vancomycin and rifampicin (rifampin) is commonly used to treat staphylococcal infections but its efficacy against methicillin-resistant Staphylococcus aureus (MRSA) biofilm is controversial. The objective of this study was to use a recently developed quantitative methodology to characterise the killing effect of vancomycin and rifampin combination against MRSA biofilm.

Methods

MRSA biofilm was exposed to escalating concentrations of vancomycin and rifampin and the viability of the biofilm-ensconced bacteria was evaluated. ADAPT II was used to model the concentration–effect relationship and determine the optimal sampling concentrations. Combination experiments were then conducted and the observations were compared with a simulated response surface representing null interaction. Finally, the pharmacodynamic interaction index (PDI) was computed as the ratio of the volumes under the observed and simulated surfaces.

Key findings

In the combination experiments, all observations showed an inferior antibacterial effect to what is expected under null interaction assumption and the PDI was estimated to be 3.36 (95% CI, 3.25 to 3.46).

Conclusions

The results of the study demonstrate in-vitro antagonism between vancomycin and rifampin against MRSA biofilm. The quantitative approach employed to quantify the antibacterial effect of the combination provides a scientific rationale for further in-vivo investigations that should allow a better understanding of the therapeutic potential of this combination in biofilm-associated MRSA infections.

Comparison of mortality associated with methicillin-resistant and methicillin-susceptible Staphylococcus aureus bacteremia: a meta-analysis

A meta-analysis was performed to summarize the impact of methicillin-resistance on mortality in Staphylococcus aureus bacteremia. A search of the MEDLINE database for studies published during the period of 1 January 1980 through 31 December 2000 and a bibliographic review identified English-language studies of S. aureus bacteremia. Studies were included if they contained the numbers of and mortality rates for patients with methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) bacteremia. Data were extracted on demographic characteristics of the patients, adjustment for severity and comorbid illness, source of bacteremia, and crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for in-hospital mortality. When the results were pooled with a random-effects model, a significant increase in mortality associated with MRSA bacteremia was evident (OR, 1.93; 95% CI, 1.54-2.42; P<.001); significant heterogeneity was present. We explored the reasons for heterogeneity by means of subgroup analyses. MRSA bacteremia is associated with significantly higher mortality rate than is MSSA bacteremia.

Positive (1-->3)-beta-D-glucan in blood components and release of (1-->3)-beta-D-glucan from depth-type membrane filters for blood processing

BACKGROUND

The false-positive elevation of plasma (1-->3)-beta-D-glucan level, a serodiagnostic test for deep-seated mycosis, is suspected in patients administered with blood components.

STUDY DESIGN AND METHODS

(1-->3)-beta-D-Glucan and endotoxin levels in blood components consisting of 12 albumins, 8 immunoglobulins, and 3 blood coagulation factors were measured by fungal infection tests (Fungitec G-test, Seikagaku Co.; the Wako WB003 test, Wako Pure Chemical Industries; and the Endospec ES test, Seikagaku Co.). In vitro release of (1-->3)-beta-D-glucan from the depth-type filters made by cellulose membrane to process blood components was analyzed through an in vitro filtration process as a source of (1-->3)-beta-D-glucan in blood components.

RESULTS

The amounts of (1-->3)-beta-D-glucan in blood components ranged from 0 to 7510 pg per mL in the Fungitec G-test, with wide variations among brands. The positive rates over 20 pg per mL were 75 percent in albumin solutions, 40 percent in blood coagulation factors, and 63 percent in immunoglobulin solutions. (1-->3)-beta-D-Glucan levels released from the five depth filters ranged from 5 to 2516 pg per mL. The (1-->3)-beta-D-glucan level in filtration fluid was decreased by rinsing with distilled water, but rebounded again during the albumin filtration process.

CONCLUSION

Depth filters are considered the source of (1-->3)-beta-D-glucan content in some blood components.

Epidemiology of vascular catheter-related bloodstream infections in a large university hospital in Israel

Intravascular catheter-related infection and associated bacteraemia constitute a serious and increasing problem among nosocomial infections. As a part of an ongoing survey of positive blood cultures, all catheter-related bloodstream infections (CR-BSI) were reviewed in the authors' Medical Center in 1996, in order to evaluate the magnitude and seriousness of this problem. The largest group (28%) of hospital-acquired bacteraemia by 1 source of infection during 1996 was CR-BSI, identified in 110 patients with 126 episodes. The vascular line was central in 83 (66%), peripheral in 24 (19%), tunnelled in 18 (14%) and arterial in 1 (1%). Among the 83 central CR-BSI no sign of local inflammation was detected in 65%. Gram-positive and gram-negative bacteria shared equal parts among the 145 blood isolates; Staphylococcus aureus was the most common species (43/145, 30%) followed by Klebsiella pneumoniae (15/145, 10%); 11 (8%) isolates were Candida species. Fungal isolates were more common among tunnelled catheter infections than among others (6/18, 33% vs. 5/108, 5%, p < 0.001). Crude mortality was 35% (38/110), while attributable mortality was 14% (15/110), mostly associated with central line infection. Catheter-associated bacteraemias cause significant morbidity and mortality, and have become the most common source of hospital-acquired bacteraemia. There is a need to implement more effective infection-control measures and more advanced technologies in an effort to reduce this unacceptably high incidence.

Non-albicans Candida species isolated from plastic devices

In this work we point out an occurrence of non-albicans Candida species isolated from catheters, cannulas and drains. We detected eight non-albicans Candida species in 49 examined samples: C. parapsilosis (n = 26), C. tropicalis (n = 12), C. krusei (n = 4), C. claussenii, C. mesenterica (n = 2 for each), C. guilliermondii, C. kefyr and C. lusitaniae (n = 1 for each). Material examined from children hospitalized in intensive care units was the most frequent. Eight samples were from the oncology department, seven from the surgery department, six from the anaesthesiology department, four from the dialysis unit, two from the hematology department, one from the internal medicine department and one from the stomatology department. We examined cannula scraping 26 times (53%), catheter scraping 14 times (28.6%) and drain scraping nine times (18.4%).