Production of biofilm by Staphylococcus aureus: Association with infective endocarditis?

OBJECTIVES

Staphylococcus aureus is a well-known biofilm-producing pathogen that is capable of causing chronic infections owing to its ability to resist antibiotic treatment and obstruct the immune response. However, the possible association between high biofilm production and infective endocarditis (IE) has not been assessed. Our objective was to compare production of biofilm by S. aureus strains isolated from patients with bacteremia and IE, catheter-related bloodstream infection (C-RBSI), or non-device associated bacteremia.

METHODS

We isolated 260 S. aureus strains from the blood of patients with bacteremia who were diagnosed during hospital admission between 2012 and 2015. Patients were divided into 3 groups according to whether they had IE, C-RBSI, or non-device associated bacteremia. Biofilm production was measured in terms of biomass and metabolic activity using the crystal violet and XTT assays, respectively. High biomass and metabolic activity rates (based on tertile ranks classification) were compared between the 3 groups.

RESULTS

The high biomass and metabolic activity rates of each group were 41.9% and 37.2% for IE, 32.5% and 35.0%, for C-RBSI, and 29.0% and 33.3% for non-device associated bacteremia (p=0.325 and p=0.885, respectively).

CONCLUSIONS

High biomass and metabolic activity levels for S. aureus isolates from IE were similar to those of S. aureus isolates from C-RBSI or non-device associated bacteremia.

Production of biofilm by Staphylococcus aureus: Association with infective endocarditis?

OBJECTIVES

Staphylococcus aureus is a well-known biofilm-producing pathogen that is capable of causing chronic infections owing to its ability to resist antibiotic treatment and obstruct the immune response. However, the possible association between high biofilm production and infective endocarditis (IE) has not been assessed. Our objective was to compare production of biofilm by S. aureus strains isolated from patients with bacteremia and IE, catheter-related bloodstream infection (C-RBSI), or non-device associated bacteremia.

METHODS

We isolated 260 S. aureus strains from the blood of patients with bacteremia who were diagnosed during hospital admission between 2012 and 2015. Patients were divided into 3 groups according to whether they had IE, C-RBSI, or non-device associated bacteremia. Biofilm production was measured in terms of biomass and metabolic activity using the crystal violet and XTT assays, respectively. High biomass and metabolic activity rates (based on tertile ranks classification) were compared between the 3 groups.

RESULTS

The high biomass and metabolic activity rates of each group were 41.9% and 37.2% for IE, 32.5% and 35.0%, for C-RBSI, and 29.0% and 33.3% for non-device associated bacteremia (p=0.325 and p=0.885, respectively).

CONCLUSIONS

High biomass and metabolic activity levels for S. aureus isolates from IE were similar to those of S. aureus isolates from C-RBSI or non-device associated bacteremia.

Effectiveness of a bundle of measures for reducing central line-associated bloodstream infections

INTRODUCTION

Catheter-associated infections are the main cause of nosocomial bacteremia. The main objective of this study was to demonstrate a possible decrease in CLABSI rates in perioperative environment after the implementation of a bundle of measures. Secondary objective was to determine which factors were associated with an increased risk of CLABSI, after the implementation of the bundle.

METHODS

Insertion bundle consisted of: subclavian vein as access of choice, disinfection with alcoholic 2% chlorhexidine, central-line full body drapes, sterile ultrasound probe-cable covers and insertion check-list. Cumulative Incidence (CI) and Incidence Density Rate (IR) of CLABSIs were compared before and after the intervention. Associations between patient or CVC characteristic and CLABSI were summarized with odds ratios and 95% confidence interval, obtained from multiple logistic regression, adjusting for age, sex, comorbidities and days with CVC.

RESULTS

Before implementing the bundle, from January to November 2016, CI of CLABSI was 5.05% and IR was 5.17 ‰. In the same period of 2018, CI of CLABSI was 2.28% and IR was 2.27 ‰, which means a reduction of 54.8% in CI (P=.072) and of 56% in IR (P=.068) In multivariable analyses, replacement of CVC was associated with a higher risk of CLABSI (OR 11.01, 95%CI 2.03-59.60, P=.005), as well as 2 or more catheterizations (OR 10.05, 95%CI 1.77-57.16, P=.009), and parenteral nutrition (OR 23.37, 95%CI 4.37-124.91, P<.001).

CONCLUSIONS

CLABSI rates decreased after the implementation of the insertion bundle. CVC replacement, 2 or more catheterizations and parenteral nutrition were associated with CLABSI after bundle implementation.

Executive summary: Diagnosis and Treatment of Catheter-Related Bloodstream Infection: Clinical Guidelines of the Spanish Society of Clinical Microbiology and Infectious Diseases (SEIMC) and the Spanish Society of Intensive Care Medicine and Coronary Units (SEMICYUC)

Catheter-related bloodstream infections (CRBSI) constitute an important cause of hospital-acquired infection associated with morbidity, mortality, and cost. The aim of these guidelines is to provide updated recommendations for the diagnosis and management of CRBSI in adults. Prevention of CRBSI is excluded. Experts in the field were designated by the two participating Societies (Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica and the Sociedad Española de Medicina Intensiva, Crítica y Unidades Coronarias). Short-term peripheral venous catheters, non-tunneled and long-term central venous catheters, tunneled catheters and hemodialysis catheters are covered by these guidelines. The panel identified 39 key topics that were formulated in accordance with the PICO format. The strength of the recommendations and quality of the evidence were graded in accordance with ESCMID guidelines. Recommendations are made for the diagnosis of CRBSI with and without catheter removal and of tunnel infection. The document establishes the clinical situations in which a conservative diagnosis of CRBSI (diagnosis without catheter removal) is feasible. Recommendations are also made regarding empirical therapy, pathogen-specific treatment (coagulase-negative staphylococci, Sthaphylococcus aureus, Enterococcus spp, Gram-negative bacilli, and Candida spp), antibiotic lock therapy, diagnosis and management of suppurative thrombophlebitis and local complications.

Diagnosis and treatment of catheter-related bloodstream infection: Clinical guidelines of the Spanish Society of Infectious Diseases and Clinical Microbiology and (SEIMC) and the Spanish Society of Spanish Society of Intensive and Critical Care Medicine and Coronary Units (SEMICYUC)

Catheter-related bloodstream infections (CRBSI) constitute an important cause of hospital-acquired infection associated with morbidity, mortality, and cost. The aim of these guidelines is to provide updated recommendations for the diagnosis and management of CRBSI in adults. Prevention of CRBSI is excluded. Experts in the field were designated by the two participating Societies (the Spanish Society of Infectious Diseases and Clinical Microbiology and [SEIMC] and the Spanish Society of Spanish Society of Intensive and Critical Care Medicine and Coronary Units [SEMICYUC]). Short-term peripheral venous catheters, non-tunneled and long-term central venous catheters, tunneled catheters and hemodialysis catheters are covered by these guidelines. The panel identified 39 key topics that were formulated in accordance with the PICO format. The strength of the recommendations and quality of the evidence were graded in accordance with ESCMID guidelines. Recommendations are made for the diagnosis of CRBSI with and without catheter removal and of tunnel infection. The document establishes the clinical situations in which a conservative diagnosis of CRBSI (diagnosis without catheter removal) is feasible. Recommendations are also made regarding empirical therapy, pathogen-specific treatment (coagulase-negative staphylococci, Staphylococcus aureus, Enterococcus spp., Gram-negative bacilli, and Candida spp.), antibiotic lock therapy, diagnosis and management of suppurative thrombophlebitis and local complications.

Evaluation of the usefulness of a quantitative blood culture in the diagnosis of catheter-related bloodstream infection: Comparative analysis of two periods (2002 and 2012)

INTRODUCTION

A retrospective study was conducted to investigate the usefulness of systematic quantitative blood culture (QBC) in the diagnosis of catheter-related bloodstream infection (CRBSI) during two 1-year periods (2002 and 2012).

METHODS

The study included all QBC requests sent to the microbiology laboratory for suspected CRBSI in adults (≥18 years) with any type of intravascular catheter (IVC). Based on a ratio of ≥4:1CFU/mL of the same microorganism between IVC blood culture from any lumen and peripheral blood culture, 5 diagnostic groups were defined: confirmed or probable CRBSI, primary BSI, other focus of infection, and colonization.

RESULTS

In total, 4521 QBCs were evaluated; 24% positive in 2002 and 16% in 2012 (P<0.0001). There were 243 episodes of suspected CRBSI (101 in 2002 and 142 in 2012). Confirmed CRBSI episodes were higher in 2002 than 2012 (56% vs 34%) (P<0.0001), whereas colonization episodes were lower (18% vs 38%) (P=0.0006). Gram-positive cocci decrease in 2012 relative to 2002 (56% vs 79.7%) (P=0.022). Almost one-third (32%) of confirmed CRBSI would have been missed if blood from all catheter lumens had not been cultured.

CONCLUSIONS

QBC is a useful method for diagnosing CRBSI. Blood samples from all catheter lumens must be cultured to avoid missing around one-third of CRBSI diagnoses.

[Results of the implementation of the Bacteremia Zero project in Catalonia, Spain]

The nationwide Bacteremia Zero (BZ) Project consists in the simultaneous implementation of measures to prevent central venous catheter-related bacteremia (CVC-B) in critically ill patients and in the development of an integral safety plan. The objective is to present the results obtained after the implementation of the BZ project in the ICUs of the Autonomous Community of Catalonia, Spain. All patients admitted to ICUs in Catalonia participating in the ENVIN-HELICS registry between January 2009 and June 2010 were included. Information was provided by 36 (92.3%) of the total possible 39 ICUs. A total of 281 episodes of CVC-B were diagnosed (overall rate of 2.53 episodes per 1000 days of CVC). The rates have varied significantly between ICUs that participated in the project for more or less than 12 months (2.17 vs. 4.27 episodes per 1000 days of CVC, respectively; p<.0001). The implementation of the BZ Project in Catalonia has been associated with a decrease greater than 40% in the CVC-B rates in the ICUs of this community, which is much higher than the initial objective of 4 episodes per 1000 days of CVC).