Gram-negative endocarditis: disease presentation, diagnosis and treatment

Infective Endocarditis by Lactobacillus Species-A Narrative Review

Bacteria of the genus Lactobacillus are microaerophilic or aerotolerant anaerobic Gram-positive non-spore-forming rods. They are considered essential members of the human gut microbiome; however, recent studies have revealed that these microorganisms are less predominant in the gut microbiome than initially thought. Lactobacillus spp. is mainly known for its use as a probiotic in foods and supplements to prevent and treat specific issues such as infectious diseases, irritable bowel syndrome, and diabetes mellitus. However, Lactobacillus spp. may occasionally cause infections such as bacteremia or infective endocarditis (IE). The present study aimed to review all cases of IE by Lactobacillus spp. and describe the epidemiology, microbiology, clinical characteristics, treatment, and outcomes of this infection by collecting relevant data from studies existing in Pubmed and Scopus until 28 September 2023. A total of 77 studies containing data for 82 patients were included. The median age was 56 years, and 69.6% were male. A prosthetic valve was present in 16% of patients, and 17.3% had previously been on probiotics. The aortic valve was the most commonly involved intracardiac site, followed by the mitral valve. Fever, embolic phenomena, sepsis, and heart failure were the most common clinical presentations. Aminoglycosides and penicillin were the most commonly used antimicrobials for definitive treatment. Surgery was performed in 53.7% of patients. Overall mortality was 17.1%. IE in prosthetic valves and presentation with shock were independently associated with overall mortality.

Infection Imaging: Focus on New Tracers?

Infections account for relevant morbidity and mortality, especially if the cardiovascular system is affected. Clinical manifestations are often unspecific, resulting in a challenging diagnostic work-up. The use of molecular imaging methods, namely [18F]FDG PET and leukocyte scintigraphy, is increasingly recognized in recently published international guidelines. However, these 2 established methods focus on the host's immune response to the pathogen and are therefore virtually unable to differentiate infection from inflammation. Targeting the microorganism responsible for the infection directly with novel imaging agents is a promising strategy to overcome these limitations. In this review, we discuss clinically approved [18F]FDG PET with its advantages and limitations in cardiovascular infections, followed by new PET-based approaches for the detection of cardiovascular infections by bacteria-specific molecular imaging methods. A multitude of different targeting options has already been preclinically evaluated, but most still lack clinical translation. We give an overview not only on promising tracer candidates for noninvasive molecular imaging of infections but also on issues hampering clinical translation.

The Bacterial Oral Microbiome in Children with Congenital Heart Disease: An Extensive Review

Children with congenital heart disease have poorer oral health compared with healthy children. Oral diseases, such as dental caries and gingivitis, are associated with the oral microbiome. The objective of this review was to find evidence of differences in the bacterial colonization of the oral cavity of children with congenital heart disease (CHD) versus healthy children. A literature review was conducted according to predetermined criteria, including the need for controlled clinical trials. Half of the 14 studies that met the inclusion criteria reported significant differences in bacterial colonization in children with congenital heart disease. A variety of influencing factors were discussed. There is some evidence for alterations in the oral microflora as a result of physiopathological and treatment-related factors in children with CHD, but additional research is required to validate these findings.

An enigmatic presentation of Escherichia coli endocarditis: Emphasizing the role of brain magnetic resonance imaging

Key Clinical Message

Infective endocarditis should be considered in any febrile individual with acute onset neurological symptoms. If suspicion is high, a negative brain computed tomography does not virtually exclude embolism, and magnetic resonance imaging is warranted.

Abstract

A diagnosis of infective endocarditis (IE) is often delayed, particularly in those infected with unusual organisms. Hereby, we report a case of a female patient presented with dysarthria, confusion, and altered mental status after being treated for Escherichia coli bacteremia. Computed tomography of the brain was unrevealing; however, scattered embolic phenomena were visualized on magnetic resonance imaging (MRI). The case underscores the importance of clinical awareness, particularly in the setting of unusual microorganisms, and the role of brain MRI in the diagnosis of IE.

Valve repair after infective endocarditis secondary to perforation caused by Streptococcus gordonii: A case report

BACKGROUND

We report a case of infective endocarditis (IE) in a patient with congenital heart valve lesions accompanied by IE, which was diagnosed based on blood culture analysis that revealed the presence of a gram-negative bacterium, Streptococcus gordonii.

CASE SUMMARY

The patient had a history of precordial valve disease diagnosed by cardiac ultrasound, as well as a 4-mo history of fever. He was subjected to comprehensive anti-infection and anti-heart failure treatment in the internal medicine department. Further examination revealed sudden dislodgement from and perforation through the aortic valve by the superfluous organisms, as well as occurrence of bacterial emboli dislodgement, which caused bacteremia and infectious shock. He recovered and was discharged from the hospital after surgical and postoperative anti-infection treatments.

CONCLUSION

We review the treatment process and highlight inspirations and reflections from this case; suggest possible future changes in treatment modalities.

Endocarditis due to Aggregatibacter Segnis: a rare case report

BACKGROUND

As a member of the HACEK group, Aggregatibacter segnis (A. segnis) is a fastidious Gram-negative coccobacillus that resides in the human oropharyngeal flora. Infective endocarditis caused by A. segnis is rarely reported.

CASE PRESENTATION

A 31-year-old male was admitted to our hospital for a 3-month history of intermittent high fever, chills, and chest distress. On presentation, he was febrile and tachycardic but otherwise with stable vital signs. Physical examination revealed systolic murmurs in the aortic and mitral valve areas. Pitting edema was evident in the lower extremities. Transthoracic echocardiography demonstrated multiple vegetations in the mitral and aortic valves. Severe regurgitation of the aortic valve and left heart dysfunction were also detected. With the suspicion of infective endocarditis and heart failure, we immediately performed microbiological tests and arranged the cardiac replacement surgery. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and metagenomic next-generation sequencing (mNGS) identified A. segnis from the bloodstream. While the surgical specimen culture was negative, the mNGS was positive for A. segnis. The patient was treated with ceftriaxone for four weeks and discharged. He remained clinically well, with laboratory results restored.

CONCLUSION

This is the first report of A. segnis infective endocarditis that combined MALDI-TOF and metagenomic next-generation sequencing in the diagnosis. The hypothesis-independent molecular techniques can outperform conventional tools to prevent diagnostic delay.

The Role of Platelets in Infective Endocarditis

Over the last decade, the incidence of infective endocarditis (IE) has increased, with a change in the frequency of causative bacteria. Early evidence has substantially demonstrated the crucial role of bacterial interaction with human platelets, with no clear mechanistic characterization in the pathogenesis of IE. The pathogenesis of endocarditis is so complex and atypical that it is still unclear how and why certain bacterial species will induce the formation of vegetation. In this review, we will analyze the key role of platelets in the physiopathology of endocarditis and in the formation of vegetation, depending on the bacterial species. We provide a comprehensive outline of the involvement of platelets in the host immune response, investigate the latest developments in platelet therapy, and discuss prospective research avenues for solving the mechanistic enigma of bacteria-platelet interaction for preventive and curative medicine.

The Assessment of Antimicrobial Resistance in Gram-Negative and Gram-Positive Infective Endocarditis: A Multicentric Retrospective Analysis

Background and Objectives: Multidrug-resistant microorganisms have made treating bacterial infections challenging. Resistance to antibiotics is expected to overcome efforts to produce new, effective antibacterial medication that is lifesaving in many situations. Infective endocarditis (IE) is a life-threatening infection that affects 5–15 per 100,000 patients annually and requires rapid antibiotic therapy to prevent morbidity and mortality. Materials and Methods: The present research assessed IE cases over five years, from a multicentric database, with the main objective of determining the degree of antibiotic resistance in these patients, stratified by Gram-positive and Gram-negative bacteria. Results: Bad oral hygiene was present in 58.6% of patients from the Gram-negative group (vs. 38.7% in the Gram-positive group). Non-valvular heart disease was identified in approximately 40% of all patients, and valvopathies in approximately 20%. It was observed that 37.9% of Gram-negative IE bacteria were resistant to three or more antibiotics, whereas 20.7% were susceptible. Among Gram-positive infections, S. aureus was the most commonly involved pathogen, with a multidrug-resistant pattern in 11.2% of patients, while Acinetobacter baumannii had the highest resistance pattern of all Gram-negative pathogens, with 27.4% of all samples resistant to three or more antibiotics. Patients with Gram-negative IE were 4.2 times more likely to die. The mortality risk was 4 times higher when bacteria resistant to two or more antibiotics was involved and 5.7 times higher with resistance patterns to three or more antibiotics than the reference group with no antibiotic resistance. Peripheral catheters were the most common cause of multi-resistant IE, followed by heart surgery, dental procedures, and ENT interventions. Conclusions: Even though Gram-positive infections were the most frequent (83.0% of all cases), Gram-negative IE infections are substantially more deadly than Gram-positive IE infections. However, it was also observed that patients with Gram-negative infections were more likely to have underlying comorbidities, be institutionalized, and be underweight. Although the Gram-negative infections were more severe, their resistance patterns were similar to Gram-positive bacteria. As resistance patterns increase, more efforts should be made to prevent a healthcare catastrophe. At the same time, careful prophylaxis should be considered in patients at risk, including those with central catheters, undergoing dental procedures, and with poor oral hygiene.

Serratia marcescens Endocarditis

Severe infections due to Serratia marcescens have been documented with increasing frequency in persons who inject drugs and are frequently associated with nosocomial outbreaks. S marcescens endocarditis is rare, and there are very few, if any, reported cases secondary to an infected wound acquired at home. We present such a case in an immunocompetent 50-year-old man with paraplegia for 30 years and chronic decubitus ulcers who likely contracted the rare opportunistic Serratia following sacral wound contact with unclean surfaces in his hotel room bathroom. While it is also possible that the organism was obtained during a hospital admission 2 months before the positive blood cultures, he was found sitting with his ulcer in direct contact with red-pigmented accumulations on the shower floor. Therefore, it is more likely that he acquired the infection outside of the hospital setting. Early and effective management with advanced cardiac techniques and appropriate antibiotic coverage resulted in a positive outcome.

Sex-related disparities in the incidence and outcomes of infective endocarditis according to type 2 diabetes mellitus status in Spain, 2016-2020

BACKGROUND

We performed a study to assess sex-differences in incidence (2016-2020), clinical characteristics, use of therapeutic procedures, and in-hospital outcomes in patients with infective endocarditis (IE) according to T2DM status.

METHODS

Ours was a retrospective cohort study using data from the Spanish National Hospital Discharge Database. We estimated the incidence of hospitalizations for IE in men and women aged ≥ 40 years with and without T2DM. Propensity score matching (PSM) and multivariable logistic regression were used to compare subgroups according to sex and the presence of T2DM.

RESULTS

From 2016 to 2020, IE was coded in 9,958 patients (66.79% men). T2DM was diagnosed in 2,668 (26.79%). The incidence of IE increased significantly from 15.29 cases per 100,000 persons with T2DM in 2016 to 17.69 in 2020 (p < 0.001). However, this increment was significant only among men with T2DM (19.47 cases per 100,000 in 2016 vs. 22.84 in 2020; p = 0.003). The age-adjusted incidence of IE was significantly higher in people with T2DM (both sexes) than in those without T2DM (IRR, 2.86; 95% CI, 2.74-2.99). The incidence of IE was higher in men with T2DM than in women with T2DM (adjusted IRR, 1.85; 95% CI, 1.54-3.31). After PSM, in-hospital mortality (IHM) was higher among T2DM women than matched T2DM men (22.65% vs. 18.0%; p = 0.018). The presence of T2DM was not associated with IHM in men or women.

CONCLUSIONS

T2DM is associated with a higher incidence of hospitalization for IE. Findings for T2DM patients who had experienced IE differed by sex, with higher incidence rates and lower IHM in men than in women. T2DM was not associated to IHM in IE in men or in women.

Infective Endocarditis by Pasteurella Species: A Systematic Review

Pasteurella spp. are non-motile, facultative anaerobic, Gram-negative coccobacilli that are commonly found in the oral cavity and the gastrointestinal tract of some animals and are known to be the cause of infections. Usually, infections by Pasteurella spp. in humans is more common in the context of an animal bite leading to a skin and soft tissue infection (SSTI). Infective endocarditis (IE) is rarely caused by Pasteurella spp.; however, it can pose diagnostic and therapeutic dilemmas due to its rarity. The aim of the present study was to systematically review all cases of IE by Pasteurella spp. in the literature. A systematic review was performed of PubMed, Scopus and the Cochrane Library (through 20 December 2021) for studies providing data on epidemiology and clinical and microbiological characteristics as well as data on treatment and outcomes of IE by Pasteurella spp. A total of 28 studies containing data for 28 patients were included. Prosthetic valve was present in 21.4% of patients. The aorta was the most commonly involved intracardiac site. Fever, sepsis, septic shock and heart failure were the most common clinical presentations. Cephalosporins, aminopenicillins and penicillin were the antimicrobials used most commonly. Overall mortality was 17.9%.

Infective Endocarditis by Moraxella Species: A Systematic Review

Moraxella catarrhalis is the most clinically relevant species among Moraxella spp. For decades, it was considered to be part of the normal human flora in the upper respiratory tract. However, since the late 1970s, considerable evidence has proposed that M. catarrhalis is an important pathogen in the human respiratory tract. Even though Infective Endocarditis (IE) is rarely caused by Moraxella spp., these infections can be problematic due to the lack of experience in their management. The aim of this study was to systematically review all published cases of IE by Moraxella spp. A systematic review of PubMed, Scopus and Cochrane library (through 8 December 2021) for studies providing epidemiological, clinical, microbiological data as well as treatment data and outcomes of IE by Moraxella spp. was performed. A total of 27 studies, containing data for 31 patients, were included. A prosthetic valve was present in 25.8%. Mitral valve was the most commonly infected site. Fever, sepsis and embolic phenomena were the most common clinical presentations. Cephalosporins, aminoglycosides, aminopenicillins and penicillin were the most commonly used antimicrobials. Overall mortality was 12.9%.