María Guembe

Synergistic effect of posaconazole and caspofungin against clinical zygomycetes.

The use of echinocandins for the treatment of invasive zygomycosis (IZ) is controversial since they show no activity in vitro. Although posaconazole shows promising results, the mortality rates of patients with IZ treated with posaconazole, at 30%, remain unacceptably high. The use of new therapies

Bloodstream infections in patients with kidney disease: risk factors for poor outcome and mortality

BACKGROUND Information regarding bloodstream infections (BSIs) in patients with kidney diseases is scarce and mainly derived from selected groups of patients. AIM To assess the characteristics of BSI in an unselected population of patients with kidney disease, including renal transplant recipients and patients with chronic kidney failure who were receiving or not receiving dialysis. METHODS A retrospective cohort study of all patients who presented with BSI in the nephrology department of a large teaching hospital. Clinical records were reviewed according to a pre-established protocol. Standard definitions were used. FINDINGS In all, 155 episodes of BSI were recorded in 108 patients. The incidence of BSI was 77.3 episodes per 1000 admissions, and 4.5 episodes per 100 patient-years. Haemodialysis patients had the highest incidence of BSI. The distribution of micro-organisms was as follows: Gram-negative, 52.3%; Gram-positive, 46.5%; fungi, 1.2%. Escherichia coli was the most frequently isolated micro-organism (27%). The BSI was classed as bacteraemia of unknown source (29.7%), urinary tract infection (23.2%), vascular access infection (17.4%), and other (29.7%). Eighteen patients (11.6%) developed septic shock or multi-organ failure, and the same proportion had persistent bacteraemia. The crude mortality rate was 14.6%. The risk factors for mortality were high Charlson index, persistent bacteraemia, and absence of fever. CONCLUSION Nephrology patients have a high incidence of BSI, particularly patients undergoing haemodialysis. The predominant micro-organisms causing BSI episodes were Gram-negative bacilli. Patients with kidney disease have high BSI-related morbidity and mortality. Risk factors for mortality were high Charlson comorbidity index and persistent BSI. The presence of fever during the BSI episodes was found to be a protective factor.

Can microbiologists help to assess catheter involvement in candidaemic patients before removal

We compared the efficacy of three techniques--minimal time to positivity (MTTP) of blood cultures (BCs), differential time to positivity (DTTP) of BCs obtained from the catheter and peripheral veins and the number of positive BCs--in predicting catheter involvement in patients with well-demonstrated catheter-related candidaemia (C-RC) and non-catheter-related candidaemia (NC-RC).C-RC was defined as isolation of the same Candida species from blood and catheter tip culture (≥15 cfu/plate). A ROC curve was created for each quantitative variable to determine the best cut-off for predicting C-RC.A total of 108 episodes of candidaemia were included (84 adults and 24 children; 67 C-RC and 41 NC-RC). These were caused mainly by C. albicans (49.1%) and C. parapsilosis (30.6%). The MTTP was significantly shorter in adult patients with C-RC than in those with NC-RC (29.8 vs. 36.8 hours; p 0.035), although no cut-off value provided acceptable accuracy. DTTP had high sensitivity but low specificity for predicting CRC. However, C-RC episodes had a significantly greater number of positive BCs than NC-RC episodes. The optimal cut-off for predicting C-RC was at least two positive BCs out of three, with the following validity values: sensitivity, 100%; specificity, 62.5%; positive predictive value, 83.3%; negative predictive value, 100%; accuracy, 87.0%.None of the tests evaluated allow a clear-cut prediction of C-RC and the criteria accepted for bacteraemia should not be automatically extrapolated to candidaemia. We found that a low number of positive BCs with Candida had a high negative predictive value for a catheter origin.

Selection of the vascular catheter: can it minimise the risk of infection?

Data regarding the prevention of catheter-related bloodstream infection (CRBSI) by making the correct decisions about when to place a central line, the appropriate selection of catheter composition and the size and number of lumens, a suitable choice of insertion site and the technique used are not well reported in recent medical literature. There is no clear evidence that the composition of the catheters presently on the market makes a significant difference to the risk of infection. Several prospective studies suggest that femoral vein location represents the highest risk of infection, followed by jugular vein and subclavian vein positioning, however, most articles do not correct for basic confounding variables. Several papers have reported that arterial catheters have a similar risk of infection as central venous catheters (CVCs). The slight increase in infection risk when using multi-lumen catheters is probably offset by their improved convenience. Current evidence does not support routine tunnelling of short-term catheters until its efficacy is evaluated at different placement sites, using specific catheters and situations and in relation to other preventive interventions. Cuffing is usually applied only to long-term tunnelled catheters. The available evidence suggests that chlorhexidine-silver sulfadiazine, minocycline-rifampicin CVCs and antifungal-coated catheters are useful in decreasing the incidence of CRBSI when other measures are not effective.

Evolution and aetiological shift of catheter-related bloodstream infection in a whole institution: the microbiology department may act as a watchtower

The incidence of central-line-associated bloodstream infection (CLA-BSI) is reported per 1000 days of catheter exposure, mainly in the intensive care unit (ICU), because recording exposure throughout an institution is not always feasible. Confirmation of catheter-related bloodstream infection (CR-BSI) requires specific laboratory testing that identifies the catheter as the source of infection. This information is available in microbiology laboratories and can be assessed using a denominator of 1000 admissions. We evaluated recent trends in the incidence and aetiology of CR-BSI and compared adult ICUs with the remaining areas of the hospital in a retrospective cohort analysis of all confirmed CR-BSIs. During the 8-year study period, we recorded 1208 episodes (8.2% of BSIs) of CR-BSI. After adjusting for the blood cultures drawn, a significant reduction in incidence was observed in adult ICUs (47%), where care bundles had been applied. The reduction was similar irrespective of whether CLA-BSI or CR-BSI was assessed. We recorded a significant reduction in the incidence of Staphylococcus aureus CR-BSI, and a significant increase in the incidence of CR-BSI caused by Enterococcus sp., Gram-negative microorganisms and fungi. The microbiology department may complement CLA-BSI/1000 catheter-days by providing CR-BSI when days of exposure are not available, because both figures are parallel. We demonstrated a significant reduction in the incidence of CR-BSI in recent years in the population admitted to adult ICUs but not in the remaining areas of the hospital. A shift in the aetiological spectrum of CR-BSI may be occurring.

Impact on knowledge and practice of an intervention to control catheter infection in the ICU

Information on the impact of care bundles has been mainly acquired in adult intensive care units (ICUs). However, specific data for educational programs are scarce. Our objective was to analyze the impact of an educational program on the knowledge and prevention of catheter-related bloodstream infection (CRBSI) in two pediatric intensive care units (P-ICUs). A prospective study was carried out at a large teaching institution in Madrid, Spain. Healthcare workers’ (HCWs) knowledge of guidelines for the prevention of CRBSI was assessed before and after the educational program using a questionnaire covering 12 issues. A 20-min program was offered to all HCWs on each ICU shift. The incidence density of CRBSI was assessed before, during, and after the educational program. A total of 174 questionnaires were completed by HCWs from both the neonatal ICU (N-ICU) and the P-ICU before the intervention and 54 were completed after the intervention (120 participants were not present during this period). The incidence density of CRBSI before, during, and after the intervention was 6.2, 5.2, and 9.3 in the N-ICU and 2.2, 3.1, and 2.9 in the P-ICU (p > 0.05). A single 20-min educational intervention on the prevention of CRBSI significantly improved HCWs’ knowledge, but was not enough to reduce the incidence density of CRBSI.

Value of Superficial Cultures for Prediction of Catheter-Related Bloodstream Infection in Long-Term Catheters: a Prospective Study

ABSTRACT Cultures taken from the skin and from the hubs of short-term central venous catheters can help us to predict catheter-related bloodstream infections (C-RBSIs). The value of these cultures for such predictions has not been assessed in long-term catheters. Our objective was to assess the value of superficial cultures for the prediction of C-RBSI among patients with long-term catheters. Over a 2-year period, we prospectively obtained cultures from the skin overlying reservoir ports (group A) and from the skin insertion site and hubs of all tunneled catheters (group B). This routine was performed by vascular and interventional radiologists immediately before catheter removal (irrespective of the reason for withdrawal). Swabs were processed semiquantitatively. Catheter tips from both groups were cultured using Makis semiquantitative technique and sonication. We also performed cultures of the reservoir ports at different sites. C-RBSI was defined as the isolation of the same species of microorganism(s) both in the colonized catheter and in at least 1 peripheral blood culture. We included 372 catheters (group A, 223; group B, 149) during the study period. The catheter colonization rate was 23.4% (87/372), and 28 patients had C-RBSI. Validity index values for the capacity of surface cultures to predict C-RBSI in groups A and B were, respectively, as follows: sensitivity, 23.5% and 45.5%; specificity, 59.7% and 63.0%; positive predictive value, 4.6% and 8.9%; and negative predictive value, 90.4% and 93.5%. Superficial cultures of patients with long-term catheters could help us to rule out the catheter as the portal of entry of bloodstream infections. Superficial cultures (from skin and hubs) proved to be a useful conservative diagnostic tool for ruling out C-RBSI among patients with long-term tunneled catheters and totally implantable venous access ports.

How Should Long-Term Tunneled Central Venous Catheters Be Managed in Microbiology Laboratories in Order to Provide an Accurate Diagnosis of Colonization?

ABSTRACT Guidelines recommend the roll-plate technique for short-term central venous catheter (CVC) tip cultures. However, the issue of whether the roll-plate technique is better than the sonication method for long-term CVCs remains unresolved. In addition, no data are available for predicting the value of direct Gram staining in anticipating catheter colonization or catheter-related bloodstream infection (CRBSI) in these long-term CVCs. Our objectives were to compare the roll-plate technique and the sonication method and to define the validity values of Gram staining for the prediction of colonization and CRBSI in patients with long-term tunneled CVCs. During the study period, all tunneled CVCs removed at our institution were prospectively and routinely sent to the microbiology laboratory for Gram staining (first) and tip culture (the Maki technique and sonication, in a random order). We received 149 tunneled CVCs, 39 (26.2%) of which were colonized and 11 (7.4%) of which were associated with CRBSI. Overall, the roll-plate method detected 94.9% of the colonized catheters, whereas sonication detected only 43.6% (P < 0.001). The validity values of Gram staining for the detection of colonization and CRBSI were as follows: a sensitivity of 35.9% to 60.0%, a specificity of 100% to 94.2%, a positive predictive value of 100% to 42.9%, and a negative predictive value of 81.5% to 97.0%. The roll-plate technique proved to be better than sonication for the detection of bacteria in long-term tunneled CVCs. Gram staining of the tips of tunneled CVCs can anticipate a positive culture and rule out CRBSI. In our opinion, direct Gram staining should be incorporated into routine microbiological assessments of long-term catheter tips.

Predictive value of superficial cultures to anticipate tunneled hemodialysis catheter–related bloodstream infection☆☆☆

We performed a prospective study in patients with tunneled catheters to assess the validity of Gram stain and superficial culture for anticipating catheter exit-site infection and hemodialysis catheter-related bloodstream infection. The sensitivity and negative predictive value were high, and we succeeded in identifying a subpopulation at low risk of infection.

Micafungin at Physiological Serum Concentrations Shows Antifungal Activity against Candida albicans and Candida parapsilosis Biofilms

ABSTRACT We assessed the in vitro activity of micafungin against preformed Candida biofilms by measuring the concentration of drug causing the most fungal damage and inhibition of regrowth. We studied 37 biofilm-producing Candida spp. strains from blood cultures. We showed that micafungin was active against planktonic and sessile forms of Candida albicans strains and moderately active against Candida parapsilosis sessile cells. Concentrations of micafungin above 2 μg/ml were sufficiently high to inactivate regrowth of Candida sessile cells.