Endocarditis due to gram-negative bacilli at a French teaching hospital over a 6-year period: clinical characteristics and outcome

Non-HACEK gram-negative bacilli endocarditis: a multicentre retrospective case-control study

BACKGROUND

Infective endocarditis (IE) caused by non-HACEK gram-negative bacilli (GNB) is poorly characterised and may be emerging as a consequence of medical progress.

METHODS

We performed an observational retrospective case-control study. Cases were non-HACEK GNB IE, definite or possible (modified Duke criteria), diagnosed in adults between 2007 and 2020 in six French referral hospitals. Two controls were included for each case (IE due to other bacteria, matched by sites and diagnosis date).

RESULTS

Non-HACEK GNB were identified in 2.4% (77/3230) of all IE during the study period, with a mean age of 69.2 ± 14.6 years, and a large male predominance (53/77, 69%). Primary pathogens were Escherichia coli (n = 33), Klebsiella sp. (n = 12) and Serratia marcescens (n = 9), including eight (10%) multidrug-resistant GNB. Compared to controls (n = 154: 43% Streptococcus sp., 41% Staphylococcus sp. and 12% Enterococcus sp.), non-HACEK GNB IE were independently associated with intravenous drug use (IVDU, 8% vs. 2%, p = .003), active neoplasia (15% vs. 6%, p = .009), haemodialysis (9% vs. 3%, p = .007) and healthcare-associated IE (36% vs. 18%, p = .002). Urinary tract was the main source of infection (n = 25, 33%) and recent invasive procedures were reported in 29% of cases. Non-HACEK GNB IE were at lower risk of embolism (31% vs. 47%, p = .002). One-year mortality was high (n = 28, 36%). Comorbidities, particularly malignant hemopathy and cirrhosis, were associated with increased risk of death.

CONCLUSIONS

Non-HACEK GNB are rarely responsible for IE, mostly as healthcare-associated IE in patients with complex comorbidities (end-stage renal disease, neoplasia), or in IVDUs.

Infective Endocarditis due to Non-HACEK Gram-Negative Bacilli: Clinical Characteristics and Risk Factors from a Prospective Multicenter Brazilian Cohort

Background: Non-HACEK Gram-negative bacilli (NGNB) infective endocarditis (IE) has a growing frequency. We aimed to describe cases of NGNB IE and find associated risk factors. Methods: We conducted a prospective observational study of consecutive patients with definitive IE according to the modified Duke criteria in four institutions in Brazil. Results: Of 1154 adult patients enrolled, 38 (3.29%) had IE due to NGNB. Median age was 57 years, males predominated, accounting for 25/38 (65.8%). Most common etiologies were Pseudomonas aeruginosa and Klebsiella spp. (8 episodes, 21% each). Worsening heart failure occurred in 18/38 (47.4%). Higher prevalence of embolic events was found (55,3%), mostly to the central nervous system 7/38 (18.4%). Vegetations were most commonly on aortic valves 17/38 (44.7%). Recent healthcare exposure was found in 52.6% and a central venous catheter (CVC) in 13/38 (34.2%). Overall mortality was 19/38 (50%). Indwelling CVC (OR 5.93; 95% CI, 1.29 to 27.3; p = 0.017), hemodialysis (OR 16.2; 95% CI, 1.78 to 147; p = 0.008) and chronic kidney disease (OR 4.8; 95% IC, 1.2 to 19.1, p = 0.049) were identified as risk factors for mortality. Conclusions: The rate of IE due to NGNB was similar to that in previous studies. Enterobacterales and P. aeruginosa were the most common etiologies. NGNB IE was associated with central venous catheters, prosthetic valves, intracardiac devices and hemodialysis and had a high mortality rate.

Escherichia coli: A Rare Cause of Prosthetic Valve Endocarditis

Prosthetic valve endocarditis (PVE) is a complication of valve replacement associated with high morbidity and mortality. Escherichia coli (E. coli) is rarely associated with infective endocarditis (IE), accounting for less than 1% of the cases reported. The low frequency is attributed to the organism's low affinity to adhere to the endocardial endothelium. Risk factors that may play a role in developing IE by E. coli include age above 70, diabetes mellitus, a genitourinary source of infection, female sex, healthcare contact, implanted endovascular devices, and immunosuppression. We present a 70-year-old Hispanic woman who arrived with constitutional symptoms and persistent urinary complaints. She had diabetes mellitus, recurrent urinary tract infections, and native mitral valve IE treated with antibiotic therapy and tissue valve replacement. The valve was replaced with a mechanical valve a second time due to malfunctioning. The patient was found to have E. coli bacteremia and ultimately diagnosed with PVE. She was treated solely with ceftriaxone and gentamicin combination therapy resulting in complete resolution of valve vegetations. Our case represents the 11th report of this uncommon disease and illustrates its epidemiology and associated risk factors. We summarize the previous 10 cases reported and highlight the lack of prospective trial data to define optimal therapy for managing PVE caused by E. coli.

Acinetobacter baumannii-induced infective endocarditis: new insights into pathophysiology and antibiotic resistance mechanisms

Infective endocarditis (IE), characterized by inflammation of the endocardial surface of the heart and its valves, results from infections caused by Staphylococcus, Streptococcus and Acinetobacter species and less commonly fungi. Acinetobacter-induced IE is a relatively rare condition with significant morbidity and mortality worldwide. Notably, its mortality rate is greater than that of endocarditis induced by Haemophilus species, Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens and Kingella kingae. Although it is rare, Acinetobacter-induced IE caused by A. baumannii might bring unique therapeutic challenges such as increased antibiotic resistance. Therefore, it is vital to understand perfectly the possible pathophysiologic and antibiotic resistance mechanisms adopted by A. baumannii during IE. This review discusses the probable underlying pathomechanisms involved in A. baumannii-induced IE and highlights the potential antibiotic resistance mechanisms, suggesting therapeutic targets for A. baumannii-induced IE.

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 in the Elderly: Challenges and Strategies

The specific management of infective endocarditis (IE) in elderly patients is not specifically addressed in recent guidelines despite its increasing incidence and high mortality in this population. The term "elderly" corresponds to different ages in the literature, but it is defined by considerable comorbidity and heterogeneity. Cancer incidence, specifically colorectal cancer, is increased in older patients with IE and impacts its outcome. Diagnosis of IE in elderly patients is challenging due to the atypical presentation of the disease and the lower performance of imaging studies. Enterococcal etiology is more frequent than in younger patients. Antibiotic treatment should prioritize diminishing adverse effects and drug interactions while maintaining the best efficacy, as surgical treatment is less commonly performed in this population due to the high surgical risk. The global assessment of elderly patients with IE, with particular attention to frailty and geriatric profiles, should be performed by multidisciplinary teams to improve disease management in this population.

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%.

Infective endocarditis by Serratia species: a systematic review

Serratia species are facultative anaerobes, non-spore-forming, motile Gram-negative bacteria. Serratia spp. are currently thought to cause a variety of infections, such as bacteremia, urinary tract infections, and pneumonia, as well as other, less common infections, including ocular infections or skin and soft tissue infections. On the other hand, Infective Endocarditis (IE) is an infrequent disease with notable morbidity and mortality. Even though IE is rarely caused by Serratia spp., these infections can be quite problematic due to the lack of experience in their management. This study aimed to systematically review all published cases of IE by Serratia spp. in the literature. A systematic review of PubMed, Scopus, and Cochrane library (through 13^th May 2021) for studies providing epidemiological, clinical, microbiological data as well as data on treatment and outcomes of IE by Serratia spp. was performed. In total, 50 studies, containing data for 72 patients, were included. A prosthetic valve was present in 18.1%. The mitral valve was the most commonly infected site, followed by the aortic valve. The diagnosis was facilitated by transthoracic echocardiography in 34.7%, while the diagnosis was set at autopsy in 22.4%. Fever, sepsis, and embolic phenomena were the most common clinical presentations, followed by heart failure. Aminoglycosides, cephalosporins, and carbapenems were the most commonly used antimicrobials. Clinical cure was noted only in 53.5%, while overall mortality was 47.2%. Having surgery along with antimicrobial treatment was independently associated with reduced overall mortality. IE by Serratia spp. was more likely to be associated with intravenous drug use, and to present with heart failure and embolic phenomena compared to IE by other non-HACEK Gram-negative bacilli, while mortality was also higher in IE by Serratia spp.

Infective endocarditis: Role of molecular techniques in early diagnosis

Infective endocarditis (IE), a heart valve infection primarily caused by bacteria such as streptococci or staphylococci, causes significant morbidity and mortality. Despite the long-term use of broad-spectrum antimicrobials, the infection is often difficult to manage. The latest diagnostic modalities for IE are discussed in this study. Blood culture use in pathogen identification can lead to loss of precious time as well as generation of false negative reports. The first steps in diagnosis are blood cultures and echocardiography, but molecular techniques can be extremely useful and may be used for an accurate and early diagnosis.

Gram-negative endocarditis: disease presentation, diagnosis and treatment

PURPOSE OF REVIEW

Gram-negative bacilli (GNB) cause between 1% and 10% of infective endocarditis (IE). Most episodes are caused by microorganisms of the Haemophilus spp., Aggregatibacter spp. Cardiobacterium spp., Eikenella spp., and Kingella spp (HACEK) group. The frequency of IE caused by non-HACEK (GNB-IE) has increased in recent years. Uncertainties persist regarding its best medical treatment and the appropriateness and timing of surgical treatment. In addition, there are new drugs with activity against multiresistant microorganisms, of which there is little experience in this disease. We review this topic by answering the most frequently asked questions that arise among our colleagues.

RECENT FINDINGS

HACEK microorganisms cause 1.5-2% of IE with only a 2% mortality. In contrast, non-HACEK GNB-IE accounts for 2.5-3% of all IE cases and is associated with nosocomial acquisition, advanced age, solid organ transplantation and 20-30% mortality. Drug addiction is important in areas with epidemic opioid abuse.

SUMMARY

The frequency of IE caused by GNB has been modified in recent years. HACEK episodes are no longer treated with ampicillin and aminoglycosides. In non-HACEK GNB-IE, combination therapy with a beta-lactam and a quinolone or aminoglycoside is recommended. The surgical indication and its value are evident in many patients. Management should rely on a collaborative group with experience in this disease.

Escherichia coli prosthetic valve endocarditis from a non-genitourinary source

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E. coli is an infrequent cause of infective endocarditis due to is limited ability to adhere to heart valves.

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There is a notable increase in the share of total cases of E. coli infective endocarditis due to prosthetic valve infections.

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There is an increased recognition of non-genitourinary sources of E. coli prosthetic valve endocarditis.

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The overall mortality rate is declining for E. coli prosthetic valve endocarditis cases.

Escherichia coli (E. coli) is a rare cause of infective endocarditis due to its lack of traditional virulence factors that promote endocardial adherence. Previous case reports of E. coli infective endocarditis demonstrate specific risk factors to include advanced age over 70, female sex, diabetes, immunosuppression, and intravascular or cardiac devices. Antecedent genitourinary infection is the most common source. We present a case of a 55-year-old Honduran man with a recent bioprosthetic mitral valve replacement and tricuspid valve repair who presented with one month of subjective fevers, night sweats, anorexia, and significant weight loss. After extensive work-up, the patient was diagnosed with E. coli infective endocarditis secondary to E. coli growth in blood cultures and a transesophageal echocardiogram (TEE) revealing a vegetation on his prosthetic mitral valve. An indolent gastrointestinal source was suspected to be the source of infection with imaging only notable for mild periappendiceal stranding concerning for a possible site of antecedent inflammation. He was treated with a 6-week course of ceftriaxone and gentamicin inpatient and then discharged on trimethoprim-sulfamethoxazole suppressive therapy with serial echocardiographic follow-up given the persistent small vegetation on repeat echocardiogram. Our case report and review of ten recent cases of prosthetic valve endocarditis described in the literature illustrates several common features of the epidemiology, presentation, and management of E. coli prosthetic valve endocarditis including more commonly reported non-genitourinary sources of bacteremia, a trend towards more frequent surgical interventions, and a declining mortality rate.

Non-HACEK gram negative bacilli endocarditis: Analysis of a national prospective cohort

BACKGROUND

Infective endocarditis (IE) due to non-HACEK bacilli (Haemophilus species, Actinobacillus, Cardiobacterium, Eikenella, or Kingella) is uncommon and poorly described. The objectives of this study were to describe non-HACEK Gram-Negative Bacilli (GNB) IE cases and compare characteristic of IE produced by Enterobacterales and non-fermenting (NF) GNB.

METHODS

From January 2008 to December 2018, 3910 consecutive patients with definitive IE diagnosis, defined with Modified Duke criteria, either clinical or pathological criteria (e.g. demonstration of non-HACEK GNB in valve culture)were prospectively included.

RESULTS

A total of 104 IE cases were caused by non-HACEK GNB (2.6%). Compared to IE due to other microorganisms (excluding HACEK GNB), patients with non-HACEK GNB IE presented with higher age (71 years [IQR 62-78] vs 68 years [IQR: 57-77]; p = 0.026), higher proportion of women (52% vs 31.5%, p < 0.001), higher Charlson Index (5 [IQR: 4-8] vs 4 [IQR 3-7], p = 0.003) and higher in-hospital mortality (36.5% vs 27.1%, p = 0.034). Enterobacterales cases were more frequently associated with genitourinary focus (32.8% vs 5.0%, p = 0.001). NFGNB endocarditis more frequently affected right valves (20.0% vs. 6.3%, p = 0.033), had more common healthcare-related acquisition (67.5% vs. 43.7%, p = 0.030) and venous catheter as focus (40.0% vs. 17.2%, p = 0.019). In the multivariant model, factors related with hospital mortality were: age (OR 1.05, 95%CI 1.00-1.09, p = 0.042), prosthetic valve (OR 2.31, 95%CI 0.90-5.88, p = 0.080), and not performing surgery when indicated (OR 3.60, 95%CI 1.17-11.05, p = 0.025).Patients treated with quinolone combination had lower mortality (OR 0.29; 95%CI 0.09-0.96; p = 0.043).

CONCLUSION

Non-HACEK GNB IE is a rare infection characterized by affecting elderly patients with high comorbidity, nosocomial acquisition and unfavorable outcome. Age, prosthetic valve and not performing surgery when indicated are associated with mortality.

Infective endocarditis caused by Enterobacteriaceae: phenotypic and molecular characterization of Escherichia coli and Klebsiella pneumoniae in Rio de Janeiro, Brazil

The etiological agent for infective endocarditis (IE), a life-threatening disease, is usually gram-positive bacteria. However, gram-negative bacteria can rarely cause IE and 4% of cases are associated with morbidity and mortality. This study aimed to characterize Escherichia coli and Klebsiella pneumoniae isolates from the blood of patients with IE. The characteristics of blood isolates were compared with those of urinary isolates from patients with urinary tract infections (UTIs). The results of this study revealed that K. pneumoniae isolates from patients with IE were phylogenetically related to those from patients with UTI. Additionally, the resistance phenotype, resistance gene, virulence gene, and plasmid profiles were similar between the blood and urinary isolates. The isolates belonging to the sequence types (STs) 76, 36, 101 (K. pneumoniae), and 69 (E. coli) are reported to be associated with drug resistance. The Enterobacteriaceae isolates from patients with IE did not produce extended-spectrum β-lactamase or carbapenemase. Additionally, this study investigated the virulence phenotype, biofilm formation ability, and the ability to adhere to the epithelial cells in vitro of the isolates. The isolates from patients with IE exhibited weaker biofilm formation ability than the urinary isolates. All isolates from patients with IE could adhere to the renal epithelial cells. However, three isolates from patients with UTIs could not adhere to the epithelial cells. The closely related K. pneumoniae isolates (648, KP1, KP2, KP3, and KP4) could not form biofilms or adhere to the epithelial cells. In summary, the molecular analysis revealed that the genetic characteristics of IE-causing K. pneumoniae and E. coli were similar to those of UTI-causing isolates. These isolates belonged to the STs that are considered treatable. Genetically similar isolates did not exhibit the same virulence phenotype. Thus, these non-hypervirulent clones must be monitored as they can cause complex infections in susceptible hosts.

Infective endocarditis by Enterobacter cloacae: a systematic review and meta-analysis

Enterobacter species are Gram-negative, non-spore-forming, facultative anaerobes typically motile due to the presence of peritrichous flagella. E. cloacae, the species responsible for the majority of Enterobacter infections in humans, is part of the intestinal microbiota and may cause infection in patients that have previously received antimicrobial therapy or who have been admitted to the Intensive Care Unit. E. cloacae may cause several infections, such as pneumonia, urinary tract, skin and soft tissue and intravascular infections. Infective Endocarditis (IE) is a rare disease with notable morbidity and mortality. Even though IE is rarely caused by E. cloacae, these infections can be problematic due to the relative lack of experience in their management. The purpose of this study was to systematically review all published cases of IE by E. cloacae in the literature. A systematic review of PubMed, Scopus and Cochrane library (through 14^th November 2020) for studies providing epidemiological, clinical, microbiological as well as treatment data and outcomes of IE by E. cloacae was performed. A total of 20 studies, containing data of 20 patients, were included. A prosthetic valve was present in 27.8%. Mitral valve was the commonest infected site, followed by aortic valve. Diagnosis was facilitated by transthoracic and transesophageal echocardiography in 38.5% each, while the diagnosis was set at autopsy in 10%. Fever, sepsis, shock and immunologic phenomena were the most common clinical presentations, followed by heart failure. Aminoglycosides, cephalosporins and carbapenems were the most common antimicrobials used. Clinical cure was noted in 75%, while overall mortality was 30%. Development of shock and treatment with the combination of piperacillin with tazobactam were associated with overall mortality.

Medically managed prosthetic valve endocarditis caused by Salmonella enteritidis

Infective endocarditis is associated with morbidity and mortality even when appropriately treated. It can be more complicated to treat when prosthetic material is present, often necessitating surgical revision as well as antimicrobial therapy. Endocarditis caused by gram-negative bacilli is a rare occurrence, with some literature and expert opinion suggesting superior outcomes with combined surgery and antibiotics when a prosthetic valve is involved. In cases where the prosthetic valve is well-functioning and undamaged, or cardiothoracic surgery represents a significant operative risk, it can be unclear how best to proceed. This report documents a case of Salmonella enterica subspecies enterica serovar enteritidis endocarditis of a mechanical mitral valve. The patient was managed with 6 weeks of intravenous antibiotics followed by suppressive oral antibiotic therapy. They remain in good health at 24 months.

The causal relationship between O2:K7:H6 extra-intestinal pathogenic Escherichia coli (ExPEC) and native valve endocarditis: a case report

Background

Native valves infective endocarditis due to Escherichia coli is still a rare disease and a particular virulence of some E.coli isolate may be suspected.

Case presentation

A 79-year-old woman presented during the post-operative period of an orthopedic surgery a urinary tract infection following obstructive ureteral lithiasis. E. coli was isolated from a pure culture of urine and blood sampled simultaneously. After evidence of sustained E.coli septicemia, further investigations revealed acute cholecystitis with the same micro-organism in biliary drainage and a native valve mitral endocarditis. E.coli was identified as O2:K7:H6, phylogenetic group B2, ST141, and presented several putative and proven virulence genes. The present isolate can be classified as both extra-intestinal pathogenic E.coli (ExPEC_JJ) and uropathogenic E. coli (UPEC_HM).

Conclusions

The relationship between the virulent factors present in ExPEC strains and some serotypes of E. coli that could facilitate the adherence to cardiac valves warrants further investigation.

Infective endocarditis by Klebsiella species: a systematic review

This study aimed to systematically analyze all cases of infective endocarditis (IE) by Klebsiella species in the literature. A systematic review of PubMed, Scopus and Cochrane library (through 27^th January 2021) for studies providing epidemiological, clinical, microbiological as well as treatment data and outcomes of IE by Klebsiella species was performed. In this review, a total of 66 studies were included, providing data for 67 patients. A prosthetic valve was present in 16.4%, while the most common causative pathogen was K. pneumoniae followed by K. oxytoca. The aortic valve was the most commonly infected intracardiac site, followed by the mitral valve. The diagnosis was based on transthoracic echocardiography in 46.2%, while the diagnosis was set at autopsy in 9.2% of included patients. Blood cultures were positive in 93.8%. Fever and sepsis were the most frequent clinical presentations, followed by embolic phenomena, paravalvular abscess, and heart failure. Cephalosporins, aminoglycosides, and carbapenems were the most frequently used antimicrobials. Surgical treatment along with antimicrobials was performed in 37.3% of included patients. Clinical cure was noted in 80.3%, while the overall mortality was 19.4%. Infection at the aortic valve was independently associated with mortality by IE. This systematic review gives a comprehensive description of IE by Klebsiella and provides information on epidemiology, clinical manifestations, therapeutic strategies and their outcomes.

Infective Endocarditis by Yersinia Species: A Systematic Review

Yersinia spp. are non-spore-forming Gram-negative bacilli. They comprise only three species known to cause disease in humans, namely Y. pestis, Y. enterocolitica and Y. pseudotuberculosis. Since infective endocarditis (IE) is rarely caused by Yersinia, the management of these infections can be problematic due to the lack of experience. The purpose of this study was to systematically review all published cases of IE by Yersinia species in the literature. A systematic review of PubMed, Scopus and Cochrane Library (through 1 November 2020) for studies providing epidemiological, clinical and microbiological information as well as data on treatment and outcomes of IE caused by Yersinia species was performed. A total of 12 studies, containing data of 12 patients, were included. A prosthetic valve was present in 17% of patients. The mitral valve was the most commonly infected site, followed by the aortic valve. Fever, sepsis and embolic phenomena were common clinical signs, followed by heart failure. Aminoglycosides, cephalosporins and quinolones were the most commonly used antimicrobials. Clinical cure was noted in 83%, while overall mortality was 17%. This systematic review describes IE by Yersinia and provides information on patients’ epidemiology, clinical signs and the related therapeutic strategies and outcomes.

Acute coronary syndrome caused by extrinsic coronary compression from an aortic root abscess in a patient with mechanical aortic valve endocarditis: a case report and literature review

Background 

Extrinsic coronary compression is an extremely rare complication of aortic root abscess formation and can manifest as an acute coronary syndrome in infective endocarditis. Optimal management strategies are unknown and therefore illustrative case reports may be informative.

Case summary 

We describe a 63-year-old man with a background history of a mechanical aortic valve who developed sepsis due to Escherichia coli bacteraemia from a presumed urinary source. He suddenly deteriorated with cardiogenic shock and anterior ST-segment elevation myocardial infarction on Day 16 and received emergency percutaneous coronary intervention for severe stenoses of left anterior descending and diagonal arteries. A transoesophageal echocardiogram 2 days later demonstrated a large aortic root abscess. He was transferred for emergency surgery which revealed a large aortic abscess surrounding the left main stem confirming extrinsic coronary compression. He received a redo tissue aortic valve replacement and repair of his abscess cavity.

Discussion 

We describe a case where percutaneous coronary intervention and emergency surgery was used to treat extrinsic compression from an aortic root abscess; a complication that is associated with a high mortality. This is also a rare case of E. coli causing prosthetic valve endocarditis. We also explore the findings of 11 previous cases of extrinsic coronary compression from aortic root abscess.

Comparison of Pseudomonas aeruginosa strains reveals that Exolysin A toxin plays an additive role in virulence

BACKGROUND

Pseudomonas aeruginosa possesses an array of virulence genes ensuring successful infection development. A two-partner secretion system Exolysin BA (ExlBA) is expressed in the PA7-like genetic outliers consisting of ExlA, a pore-forming toxin and ExlB transporter protein. Presence of exlBA in multidrug-resistant (MDR) strains has not been investigated, particularly in the strains isolated from wounded soldiers.

METHODS

We screened whole genome sequences of 2439 MDR- P. aeruginosa strains for the presence of exlBA. We compiled all exlBA positive strains and compared them with a diversity set for demographics, antimicrobial profiles and phenotypic characteristics: surface motility, biofilm formation, pyocyanin production and hemolysis. We compared the virulence of strains with comparable phenotypic characteristics in Galleria mellonella.

RESULTS

We identified 33 exlBA-positive strains (1.5%). These strains have increased antibiotic resistance, they are more motile, produce more robust biofilms and have comparable pyocianin production with the diversity set despite the phenotypic differences within the group. In in vivo infection models, these strains were less virulent than Type III Secretion System (T3SS) positive counterparts.

CONCLUSIONS

exlBA-positive strains are wide spread among the PA7-like outliers. While not as virulent as strains possessing T3SS, these strains exhibit phenotypic features associated with virulence and are still lethal in vivo.

Infective endocarditis by Acinetobacter species: a systematic review

A. baumannii - A. calcoaceticus complex infections are increasingly frequent, especially in intensive care units. Such infections are associated with a mortality that can be as high as 62%. On the other hand, infective endocarditis (IE) is an uncommon disease with notable morbidity and mortality. Even though IE is rarely caused by Acinetobacter species, these infections can be particularly problematic due to increasing antimicrobial resistance. The purpose of this study was to systemically review all published cases of IE by Acinetobacter species in the literature. A systematic review of PubMed, Scopus and Cochrane library (through 25 April 2020) for studies providing epidemiological, clinical, microbiological as well as treatment data and outcomes of IE by Acinetobacter species was performed. A total of 35 studies, containing data of 37 patients, were included. A prosthetic valve was present in 40.5%, while the most common causative pathogen was A. baumannii - A. calcoaceticus complex, followed by A. lwoffii. Aortic valve was the commonest infected site, followed by mitral valve. Diagnosis was set with transthoracic echocardiography in 48.6%, while the diagnosis was set at autopsy in 20%. Fever and sepsis were the commonest clinical presentations, followed by heart failure and embolic phenomena. Aminoglycosides, cephalosporins and carbapenems were the commonest antimicrobials used. Clinical cure was noted in 70.3%, while overall mortality was 32.4%. Development of heart failure was independently associated with mortality by IE. This systematic review thoroughly describes IE by Acinetobacter and provides information on epidemiology, clinical presentation, treatment and outcomes.

Infective endocarditis by Proteus species: a systematic review

Proteus spp. are members of the Enterobacteriaceae family and are Gram-negative, rod-shaped bacteria known to mainly cause urinary tract infections (UTIs) in humans. However, even though scarce evidence exists suggesting their potential to cause infective endocarditis (IE), a study summarizing the existing evidence is lacking. The purpose of this study was to systemically review all published cases of IE by Proteus species in the literature. A systematic review of PubMed, Scopus and Cochrane Library (through 5^th May 2020) for studies providing epidemiological, clinical and microbiological data as well as data on treatment and outcomes of IE by Proteus species was performed. A total of 16 studies, containing data of 16 patients, were included. A prosthetic valve was present in 25%, while the most common causative pathogen was P. mirabilis. Aortic valve was the most common infected site in 33.3%, followed by mitral valve in 26.7%. Diagnosis was set with transesophageal echocardiography in 37.5%, and transthoracic echocardiography in 25%, while the diagnosis was set at autopsy in 25%. Fever and sepsis were present in 100% and 84.6%, respectively. Aminoglycosides and cephalosporins were the most common antimicrobials used for treatment. Clinical cure was noted in 62.5%, while overall mortality was 43.8%. This systematic review describes IE by Proteus species in detail and provides information on epidemiology, clinical presentation, treatment and outcomes.

Epidemiology and outcomes of non-HACEK infective endocarditis in the southeast United States

Objectives

Infective endocarditis (IE) with non-HACEK Gram-negative (GN) organisms is rare, but associated with poor outcomes. The purpose of this study was to quantify the microbiology, treatment strategies, and frequency of poor outcomes in patients with non-HACEK GN IE.

Materials

Retrospective cohort of adults with definite non-HACEK GN IE from 1/11-1/19. The primary endpoint was poor patient outcome, defined as a composite of all-cause death or infection-related readmission within 90-days of index infection.

Results

43 patients were included: 51% patients were men, and the median (IQR) age was 40 (31–50) years. Forty patients reported injection drug use. The most common organisms were Pseudomonas aeruginosa (68%) and Serratia marcescens (9%). Seventy-six percent of patients received definitive combination therapy; the most common antibiotics used in combination with a β-lactam were aminoglycosides (50%) and fluoroquinolones (34%). Three patients discontinued combination therapy due to toxicity. Twelve-month, all-cause mortality and readmission was 30% and 54%, respectively. In multivariable logistic regression, variables independently associated with composite poor outcome were receipt of fluoroquinolone-based IE combination therapy and septic shock.

Conclusions

Long-term mortality and readmission rates were high. Patients who received fluoroquinolone-based IE combination therapy more frequently developed poor outcomes than those who did not.

Extended spectrum beta lactamase producing Escherichia coli tricuspid valve endocarditis

Escherichia coli is a rare cause of endocarditis. This article reports an 82-year-old male with a mechanical aortic valve replacement who was admitted for fever and fatigue. He was diagnosed with a tricuspid valve endocarditis caused by an extended spectrum beta lactamase producing Escherichia coli following positive blood cultures and echocardiography. He received six weeks of imipenem / cilastatin and subsequently improved and was discharged with ambulatory follow ups with his infectious disease specialist.

Native valve infective endocarditis due to ampicillin-resistant Escherichia coli in the postoperative period of a right radical nephrectomy due to xanthogranulomatous pyelonephritis

Infective endocarditis (IE) due to Escherichia coli is a rare disease, although increasingly frequent. Persistent fever in septic patients despite adequate treatment raises the need to consider IE as a differential diagnosis. We present the case of a 36-year-old male patient who underwent a radical right nephrectomy as a result of diagnosis of xanthogranulomatous pyelonephritis, presenting in the postoperative period a state of septic shock with persistent fever of 41°C. Given the finding of a new-onset murmur, he was diagnosed with a mitroaortic IE by means of a transesophageal echocardiogram (TEE), having to undergo cardiac surgery for valve replacement. After multiple postoperative complications, he is successfully discharged.

Compassionate Use of Cefiderocol as Adjunctive Treatment of Native Aortic Valve Endocarditis Due to Extremely Drug-resistant Pseudomonas aeruginosa

Serious infections such as endocarditis due to extremely drug-resistance gram-negative bacteria are an increasing challenge. Here, we present successful adjunctive use of cefiderocol for a patient with persistently bacteremic healthcare-associated native aortic valve endocarditis due to an extended-spectrum beta-lactamase-positive Pseudomonas aeruginosa susceptible in vitro only to colistin, following failure of conventional therapeutic options.

Escherichia coli endocarditis of a native mitral valve

Escherichia coli (E.coli) is a rare cause of endocarditis, although is a common causative agent of bacteremia. An 89-year-old woman presented with recurrent episodes of fever and persistent E. coli bacteremia with 3-month duration, despite antimicrobial therapy. At first, a urinary tract infection was diagnosed and later a mycotic aneurysm of the abdominal aorta was found and required an endovascular repair. The persistence of fever and the evidence of a systolic murmur at the mitral focus raised the suspicion of endocarditis. A transesophageal echocardiogram and a cardiac Magnetic Resonance Imaging (MRI) confirmed the presence of a vegetation at the mitral valve and the patient was treated with ceftriaxone. The presence of comorbid conditions and certain bacterial virulence factors predispose to this rare condition. A high level of suspicion is important to early diagnosis and prompt therapy.

Non-HACEK Gram-negative bacillus endocarditis

PATIENTS AND METHODS

Retrospective analysis of clinical data using 26 diagnosed non-HACEK Gram-negative infective endocarditis cases from nine hospitals in Turkey.

RESULTS

Mean age of patients was 53 (28-84) years, with a 23% case fatality. Nineteen (73%) of the 26 patients had at least one predisposing factor. The presence of a central venous catheter was the most common predisposing factor (7/26 patients). Pseudomonasaeruginosa (7/26 patients) and Escherichiacoli (7/26 patients) were the most common pathogens. The median duration of the antibiotic therapy was 42 days (range 3-84 days). Surgical procedures were performed in 10 patients. The case fatality was similar in patients who did or did not undergo surgery (20% vs. 25%).

Native valve endocarditis due to Escherichia coli infection: a case report and review of the literature

Background

Infective endocarditis due to Escherichia coli is a rare disease but is increasing in frequency, especially among older women. In addition, its mortality rate is higher than that of endocarditis due to the HACEK-group gram-negative bacteria (Haemophilus spp., Aggregatibacter spp., Cardiobacterium hominis, Eikenella corrodens, and Kingela spp.).

Case presentation

A 58-year-old Japanese woman with a history of alcohol abuse was admitted to our hospital because of a fever. She was diagnosed with infective endocarditis due to E. coli based on repeated blood cultures and transthoracic echocardiography, which revealed vegetations attached to the anterior leaflet and chordae tendineae of the mitral valve. Despite administration of sulbactam/ampicillin and gentamycin, she developed purulent spondylitis during hospitalization and required treatment with meropenem administration for 6 weeks, leading to resolution of the endocarditis. She took oral levofloxacin for 2 months, and the spondylitis was completely cured 7 months after discharge.

Conclusion

Escherichia coli affects native valves without degenerative valvulopathy rather than prosthetic valves, especially in patients with risk factors such as an immunosuppressive status, excessive alcohol consumption, or treatment with hemodialysis. Peripheral embolization, congestive heart failure, and valve-ring abscesses are major complications of E. coli endocarditis; notably, infective myocarditis can also occur. The mortality and surgical intervention rates are 21% and 42%, respectively. Physicians should be cognizant of the necessity of surgical intervention when E. coli endocarditis is resistant to antibiotic therapy.

[Infective endocarditis due to non-HACEK gram-negative bacilli in a Level III cardiovascular center in Argentina (1998-2016)]

Non-HACEK Gram-negative bacilli are a rare cause of infective endocarditis. Epidemiological, diagnostic and prognostic aspects of this entity are little known, and there is limited experience. The aim of this study was to analyze the clinical, microbiological and in-hospital outcomes of non-HACEK Gram negative bacilli endocarditis and to compare them with those due to other microorganisms.

Risk Factors and Outcomes of Endocarditis Due to Non-HACEK Gram-Negative Bacilli: Data from the Prospective Multicenter Italian Endocarditis Study Cohort. Antimicrob Agents Chemother. 2018;62:e02208-17. [PMID: 29378721 DOI: 10.1128/aac.02208-17]

The objective of this study was to investigate predisposing factors and outcomes of infective endocarditis (IE) caused by non-HACEK Gram-negative bacilli (GNB) in a contemporary multicenter cohort. Patients with IE due to GNB, prospectively observed in 26 Italian centers from 2004 to 2011, were analyzed. Using a case-control design, each case was compared to three age- and sex-matched controls with IE due to other etiologies. Logistic regression was performed to identify risk factors for IE due to GNB. Factors associated with early and late mortality were assessed by Cox regression analysis. The study group comprised 58 patients with IE due to GNB. We found that Escherichia coli was the most common pathogen, followed by Pseudomonas aeruginosa and Klebsiella pneumoniae The genitourinary tract as a source of infection (odds ratio [OR], 13.59; 95% confidence interval [CI], 4.63 to 39.93; P < 0.001), immunosuppression (OR, 5.16; 95% CI, 1.60 to 16.24; P = 0.006), and the presence of a cardiac implantable electronic device (CIED) (OR, 3.57; 95% CI, 1.55 to 8.20; P = 0.003) were factors independently associated with IE due to GNB. In-hospital mortality was 13.8%, and mortality rose to 30.6% at 1 year. A multidrug-resistant (MDR) etiology was associated with in-hospital mortality (hazard ratio [HR], 21.849; 95% CI, 2.672 to 178.683; P = 0.004) and 1-year mortality (HR, 4.408; 95% CI, 1.581 to 12.287; P = 0.005). We conclude that the presence of a genitourinary focus, immunosuppressive therapy, and an indwelling CIED are factors associated with IE due to GNB. MDR etiology is the major determinant of in-hospital and long-term mortality.

Convexity Subarachnoid Hemorrhage, Pseudomonas Aeruginosa (PA) Infective Endocarditis and Left Atrial Appendage Occluder (LAAO) Device Infection. A Case Report

An 83 year-old-man with left atrial appendage occluder (LAAO) developed Pseudomonas Aeruginosa (PA) infective endocarditis. MRI at day 3 of onset showed distal small infarcts in both middle cerebral arteries and left postero-inferior cerebellar artery territories. MRI at day 6 revealed two sites of convexity subarachnoid hemorrhage (cSAH). MRA and CTA failed to reveal a Mycotic aneurysm.

The radiologic findings favor the assumption of necrosis of distal branches of mca or of pial arteries wall.

This case present three unusual features: the presence of localized cSAH after initiation of antibiotherapy without mycotic aneurysm being individualized; the late occurrence of infective endocarditis after LAAO implantation; the very rare occurrence of PA in prosthetic infections.