Enterococcus faecalis in blood cultures-a prospective study on the role of persistent bacteremia

Enterococcal-host interactions in the gastrointestinal tract and beyond

The gastrointestinal tract (GIT) is typically considered the natural niche of enterococci. However, these bacteria also inhabit extraintestinal tissues, where they can disrupt organ physiology and cause life-threatening infections. Here, we discuss how enterococci, primarily Enterococcus faecalis, interact with the intestine and other host anatomical locations such as the oral cavity, heart, liver, kidney, and vaginal tract. The metabolic flexibility of these bacteria allows them to quickly adapt to new environments, promoting their persistence in diverse tissues. In transitioning from commensals to pathogens, enterococci must overcome harsh conditions such as nutrient competition, exposure to antimicrobials, and immune pressure. Therefore, enterococci have evolved multiple mechanisms to adhere, colonize, persist, and endure these challenges in the host. This review provides a comprehensive overview of how enterococci interact with diverse host cells and tissues across multiple organ systems, highlighting the key molecular pathways that mediate enterococcal adaptation, persistence, and pathogenic behavior.

Is It Useful to Repeat Blood Cultures in Endocarditis Patients? A Critical Appraisal

BACKGROUND

Previous guidelines for endocarditis have suggested repeating blood cultures until they become negative, with limited evidence.

METHODS

Literature reviews were conducted (1) on the incidence of persistent bacteremia and association with outcome and (2) on timing of valve culture negativization to examine the claim for prolongation of antibiotic therapy starting from negative blood cultures.

RESULTS

Persistent bacteremia and fever may be present in the first 3 days of endocarditis, despite treatment, and are more common in Staphylococcus (especially MRSA) and Enterococcus species. Persistent bacteremia (48-72 h), persistent infection (day 7), and new onset septic shock are related and predict in-hospital mortality. It is, however, persistent infection at day 7 and septic shock that primarily determine the infectious course of endocarditis, and not persistent bacteremia. Valve cultures at surgery become negative in most cases (>85-90%) after 14-21 days of antibiotic therapy, with no calculated benefit for prolonging therapy after 21 days.

CONCLUSIONS

Persistent infection at 7 days after appropriate antibiotic therapy is a better key event for prognosis then positive or negative blood cultures at 48-72 h. Therapy prolongation from the day of negative blood cultures is not reasonable. There is no need to survey blood cultures in endocarditis patients after starting therapy.

Bacteraemia with gram-positive bacteria-when and how do I need to look for endocarditis?

BACKGROUND

Patients with bacteraemia caused by gram-positive bacteria are at risk for infective endocarditis (IE). Because IE needs long antibiotic treatment and sometimes heart valve surgery, it is very important to identify patients with IE.

OBJECTIVES

In this narrative review we present and discuss how to determine which investigations to detect IE that are needed in individual patients with gram-positive bacteraemia.

SOURCES

Published original studies and previous reviews in English, within the relevant field are used.

CONTENT

First, the different qualities of the bacteraemia in relation to IE risk are discussed. The risk for IE in bacteraemia is related to the species of the bacterium but also to monomicrobial bacteraemia and the number of positive cultures. Second, patient-related factors for IE risk in bacteraemia are presented. Next, the risk stratification systems to determine the risk for IE in gram-positive bacteraemia caused by Staphylococcus aureus, viridans streptococci, and Enterococcus faecalis are presented and their use is discussed. In the last part of the review, an account for the different modalities of IE-investigations is given. The main focus is on echocardiography, which is the cornerstone of IE-investigations. Furthermore, 18F-fluorodesoxyglucose positron emission tomography/computed tomography and cardiac computed tomography are presented and their use is also discussed. A brief account for investigations used to identify embolic phenomena in IE is also given. Finally, we present a flowchart suggesting which investigations to perform in relation to IE in patients with gram-positive bacteraemia.

IMPLICATIONS

For the individual patient as well as the healthcare system, it is important both to diagnose IE and to decide when to stop looking for IE. This review might be helpful in finding that balance.

State-of-the-Art Review: Persistent Enterococcal Bacteremia

Persistent enterococcal bacteremia is a commonly encountered and morbid syndrome without a strong evidence base for optimal management practices. Here we highlight reports on the epidemiology of enterococcal bacteremia to better describe and define persistent enterococcal bacteremia, discuss factors specific to Enterococcus species that may contribute to persistent infections, and describe a measured approach to diagnostic and therapeutic strategies for patients with these frequently complicated infections. The diagnosis of persistent enterococcal bacteremia is typically clinically evident in the setting of repeatedly positive blood culture results; instead, the challenge is to determine in an accurate, cost-effective, and minimally invasive manner whether any underlying nidus of infection (eg, endocarditis or undrained abscess) is present and contributing to the persistent bacteremia. Clinical outcomes for patients with persistent enterococcal bacteremia remain suboptimal. Beyond addressing host immune status if relevant and pursuing source control for all patients, management decisions primarily involve the selection of the proper antimicrobial agent(s). Options for antimicrobial therapy are often limited in the setting of intrinsic and acquired antimicrobial resistance among enterococcal clinical isolates. The synergistic benefit of combination antimicrobial therapy has been demonstrated for enterococcal endocarditis, but it is not clear at present whether a similar approach will provide any clinical benefit to some or all patients with persistent enterococcal bacteremia.

Rapid and simultaneous multiepitope antigen-based detection of Enterococcus by microscale thermophoresis and immunomagnetic separation

Background

Generally, enterococci bacteria cause nosocomial infections and are major indicators of bacterial contamination in marine bathing beach. However, a method for the rapid and simultaneous detection of multiple pathogenic enterococci has not been developed on account of the wide variety of pathogenic enterococci and their existence in complex matrices.

Methods

Immunoinformatics tools were used to design a multi-epitope antigen for the detection of various pathogenic enterococci by using the sequence of dltD gene on enterococci lipoteichoic acid (LTA) surface, which is associated with toxicological effects. The multi-epitopes included enterococci such as Enterococcus faecalis, E. gallinarum, E. raffinosus, E. durans, E. faecium, E. hirae, E. thailandicus, E. casseliflavus, E. avium, E. mundtii, E. lactis, E. solitarius, E. pseudoavium, and E. malodoratum. Microscale thermophoresis (MST) and western blot were carried out to detect the affinity between multi-epitope antigens and antibodies and between multi-epitope antibodies and bacteria. Furthermore, the detection of pathogenic enterococci was carried out by using immunomagnetic beads (IMBs) and immune chromatographic test strip (ICTS).

Results

The multi-epitope antibody had a satisfactory affinity to the antigen and enterococci. IMBs and ICTS were detected with a minimum of 101 CFU/mL and showed incompatibility for Vibrio parahemolyticus, V. vulnifcus, V. harveyi, V. anguillarum, and Edwardsiella tarda.

Implication

The present study demonstrated that the multi-epitope antigens exhibited excellent specificity and sensitivity, making them highly suitable for efficient on-site screening of enterococci bacteria in marine bathing beaches.

Polygonatum sibiricum saponin Exerts Beneficial Hypoglycemic Effects in Type 2 Diabetes Mice by Improving Hepatic Insulin Resistance and Glycogen Synthesis-Related Proteins

Type 2 diabetes mellitus (T2DM) is a systemic metabolic disorder characterized by insulin deficiency and insulin resistance. Recently, it has become a significant threat to public health. Polygonatum sibiricum saponin (PSS) has potential hypoglycemic effects, but its specific mechanism needs further study. In this study, PSS significantly decreased the level of blood glucose, water intake, and the organ index in diabetic mice. Meanwhile, PSS effectively reduced the content of total triglyceride (TG), total cholesterol (TCHO), low-density lipoprotein cholesterol (LDL-C), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) in the blood, and increased the content of high-density lipoprotein cholesterol (HDL-C). This suggests that PSS could reduce the content of blood lipids and initially improve the damage of hepatocytes. We found that PSS alleviated hepatic insulin resistance, repaired islet beta cells, and enabled insulin to play its biological role normally. It also improved oral glucose tolerance and abated serum lipopolysaccharide (LPS) and glycosylated hemoglobin (HbA1c) levels in T2DM mice. Furthermore, studies have found that PSS increased the content of phosphorylated protein kinase B (AKT), thereby promoting the effect of glucose transporter 4 (GLUT-4), and activating glycogen synthase kinase 3beta (GSK-3β) and glycogen synthase (GS) proteins to promote hepatic glycogen synthesis. Finally, we found that PSS could promote the growth of beneficial bacteria such as Bifidobacterium and Lactobacillus, reduce the growth of harmful bacteria such as Enterococcus and Enterobacter, and preliminarily improve the composition of important bacteria in the intestine. These studies indicate that PSS has an excellent hypoglycemic effect, which provides a potential new treatment for T2DM and guidance for more in-depth research.

Enterococcus faecalis bacteremia, cardiac implantable electronic device, extraction, and the risk of recurrence

PURPOSE

In all patients with cardiac implantable electronic devices (CIED) and Enterococcus faecalis bacteremia (EfsB), endocarditis (IE) and CIED infection should be suspected. Guidelines recommend extraction of the CIED when CIED infection or IE is diagnosed. Whether extraction of the CIED should be done in other situations with EfsB is not known. We aimed to describe the management and outcome of patients with CIED and monomicrobial EfsB, in relation to extraction and recurrent EfsB.

METHODS

A population-based cohort of patients with monomicrobial EfsB from January 2014 to November 2020 was identified through microbiology registers in the Region Skåne, Sweden. Data on CIED and other clinical features were collected from medical records.

RESULTS

Among 1087 episodes of EfsB, 72 patients with CIED and monomicrobial EfsB were identified. Five of these patients were diagnosed with IE (7%), three of whom had echocardiographic changes on the CIED. Four CIED were extracted (6%). Recurrences were found in seven of 68 patients (10%) not subjected to extraction and in none of the extracted. In the group of patients without extraction, community acquisition and predisposition for IE were significantly associated with recurrent infection in univariate analyses. No infections involving the CIED were diagnosed during the recurrences.

CONCLUSIONS

In patient with monomicrobial EfsB, it seems safe to omit extraction if no structural changes are found on the CIED.