Cause Of Infective Endocarditis Research Articles

Haemophilus influenzae endocarditis: a case report and literature review.

Haemophilus influenzae (HI) is an exceedingly rare cause of infective endocarditis (IE). We present a case of a 90-year-old female diagnosed with HI-IE involving the native tricuspid valve in the absence of traditional risk factors for right-sided endocarditis. She was treated with a 5-week course of IV Ampicillin from negative cultures and suffered no complications. We also conducted a thorough literature review through PubMed and Google Scholar, which yielded a mere 15 reported cases of HI-IE. Fourteen of the reported HI-IE cases included epidemiological data, showing no gender predominance. The mean age of the subjects was 39.5, with the mitral valve being the most implicated (64%) and tricuspid valve involvement being rare (21%). Native tricuspid valve IE is an uncommon entity, especially in the absence of IV drug use. Haemophilus influenzae is an extremely rare cause of IE, with a literature review showing merely 15 reported cases. This article cites the 16th case of HI-IE published in the literature.

Bacterial endocarditis caused by contact lens usage

A 17-year-old female was transferred to our hospital due to high fever, general fatigue, and dim eyesight. Three weeks before, she had used cosmetic colored contact lenses and then suffered from bloodshot eyes associated with dim eyesight. Intermittent fever and general fatigue were followed by eye symptoms. Echocardiography revealed moving vegetation on the posterior leaflet of the mitral valve associated with mild mitral valve regurgitation. There were no infectious sites in systemic examinations; thus, the cause of infective endocarditis was considered the infection due to contact lens usage. The patient initially received mitral valve plasty associated with the removal of infective sites. However, redo surgery was necessary 19 days later due to the relapse of infection, and the mitral valve was replaced by bioprosthesis. Traumatic injury of vessels due to inappropriate contact lens usage seemed to lead to systemic hematogenous infection and subsequent endocarditis. We report a rare case of infective endocarditis which was caused by contact lens usage.

C-terminal deletion of RelA protein is suggested as a possible cause of infective endocarditis recurrence with Enterococcus faecium.

Infective endocarditis (IE) caused by Enterococcus spp. represents the third most common cause of IE, with high rates of relapse compared with other bacteria. Interestingly, late relapses (>6 months) have only been described in Enterococcus faecalis, but here we describe the first reported IE relapse with Enterococcus faecium more than a year (17 months) after the initial endocarditis episode. Firstly, by multi locus sequence typing (MLST), we demonstrated that both isolates (EF646 and EF641) belong to the same sequence type (ST117). Considering that EF641 was able to overcome starvation and antibiotic treatment conditions surviving for a long period of time, we performed bioinformatic analysis in identifying potential genes involved in virulence and stringent response. Our results showed a 13-nucleotide duplication (positions 1638-1650) in the gene relA, resulting in a premature stop codon, with a loss of 167 amino acids from the C-terminal domains of the RelA enzyme. RelA mediates the stringent response in bacteria, modulating levels of the alarmone guanosine tetraphosphate (ppGpp). The relA mutant (EF641) was associated with lower growth capacity, the presence of small colony variants, and higher capacity to produce biofilms (compared with the strain EF646), but without differences in antimicrobial susceptibility patterns according to standard procedures during planktonic growth. Instead, EF641 demonstrated tolerance to high doses of teicoplanin when growing in a biofilm. We conclude that all these events would be closely related to the long-term survival of the E. faecium and the late relapse of the IE. These data represent the first clinical evidence of mutations in the stringent response (relA gene) related with E. faecium IE relapse.

An Uncommon Aetiology of Native Valve Infective Endocarditis: Corynebacterium glutamicum Infective Endocarditis

Corynebacterium glutamicum is a rare cause of infective endocarditis increasingly identified as a pathogen causing significant morbidity and mortality. We report a middle-age female with underlying end-stage renal failure who developed Corynebacterium glutamicum catheter-related bloodstream infection and eventually succumbed. This case highlights the importance of recognizing Corynebacterium as an emerging nosocomial pathogen and early management to improve clinical outcome.

Clinical Manifestations and Treatment Outcomes of Brucella Endocarditis: A Retrospective Cohort Study at a Tertiary Cardiac Centre in Bengaluru, Karnataka, India

Introduction: Brucella is a rare cause of Infective Endocarditis (IE), requiring prompt early recognition and treatment to prevent life-threatening complications. Diagnosis is often missed or delayed, leading to an increase in cardiac morbidity and mortality. Aim: To analyse the clinical profile, laboratory parameters, cardiac manifestations, management patterns, and outcomes of Brucella endocarditis. Materials and Methods: A retrospective cohort study was conducted at the Department of Cardiology, Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bangaluru, Karnataka, India on patients with blood culture-confirmed Brucella endocarditis, diagnosed using modified Duke’s criteria between January 2010 and December 2021. The present study evaluated the clinical presentation, treatment modalities, and outcomes. Descriptive statistical analyses were performed. Results: A total of 34 cases were identified during the study period. The mean age of the patients was 35.6±14 years (age range: 15-66 years), with 82.4% males and 17.6% females. Underlying valvular heart disease was present in 82.4% of the patients, while 17.6% had no pre-existing valvular heart disease. Both aortic and mitral valves were involved with equal frequency. All patients presented with fever. Most patients had a normal leukocyte count (61.8%). Thrombocytopenia (32.3%) and pancytopenia (17.6%) were also observed. Large vegetations (>1 cm) were seen in 38.2% of patients, and complications related to IE were observed in 35.2%. The majority of patients (82.4%) were managed medically alone in the acute phase. The antibiotic regimen of doxycycline with rifampicin combined with intravenous gentamicin was used in the majority of the patients. The observed mortality rate was 17.6%. Conclusion: Brucella endocarditis can present with thrombocytopenia/pancytopenia along with normal or reduced leukocyte count. The addition of intravenous gentamicin to oral therapy may reduce relapse rates.

Features of infective endocarditis in a contemporary cohort of persons who inject drugs: a matched comparison analysis of long-term prognostic factors.

The objective of the study was to assess the short- and long-term mortality of infective endocarditis (IE) among people who inject drugs (PWID). Using prospectively collected data on hospitalized patients (years 2000 through 2021) with IE, PWID were identified and included in this study. Survival analysis was performed to analyze short- and long-term mortality and study their risk factors among PWID and a matched group of non-intravenous drug users (N-IDU). In a study of 485 patients admitted for IE, 55 (11%) of them were PWID. These PWID patients were 1:1 age- and sex- matched to an N-IDU group (N = 55 per group). Both groups had similar baseline comorbid conditions, including congestive heart failure, type 2 diabetes, and neoplastic diseases. However, PWID were more likely to have HCV co-infection (62% vs 16%, respectively, p < 0.001) and advanced liver disease/cirrhosis (52% vs 7.9%, respectively, p < 0.001). IE in PWID more often affected the tricuspid valve (42% vs 22%, respectively, p = 0.024) and presented with more embolic events (66% vs 35%, respectively, p < 0.01). S. aureus was the primary cause of IE in PWID (44% vs 21%, respectively, p = 0.01). After adjusting for other variables, PWID (HR = 2.99, 95% CI [1.06, 8.43], p = 0.038) and valve bioprosthetic replacement (HR = 5.37, 95% CI [1.3, 22.1], p = 0.02) were independently associated with increased mortality risk, whereas IE caused by tricuspid valve infection was associated with reduced mortality risk (HR = 0.25, 95% CI [0.06, 0.97], p = 0.046). In this cohort, PWID had increased risk of long-term mortality after hospital discharge for IE, when compared to matched N-IDU with similar baseline characteristics. The reasons behind the significant increase in mortality warrant further investigation.

Streptococcus gordonii infective endocarditis complicated by brain abscess in a patient with a congenital bicuspid aortic valve: a case report

Abstract Background Infective endocarditis is associated with significant morbidity and mortality. Oral trauma through dental procedures can result in infective endocarditis through displacement of commensal organisms into the bloodstream. Streptococcus gordonii is an oral commensal and is rarely implicated as a cause of infective endocarditis but should be considered in febrile patients with a recent history of odontological procedures. Case summary We present a case of a previously healthy 26-year-old woman who presented with a 2-month history of fevers. Blood cultures on admission were positive for S. gordonii. Echocardiography demonstrated a congenital bicuspid aortic valve with vegetations and abscess, supporting a diagnosis of infective endocarditis. A magnetic resonance imaging (MRI) brain revealed a small cerebral empyema. She was treated with intravenous antibiotics and underwent an aortic valve replacement. Discussion Bicuspid aortic valve predisposes to infective endocarditis, and these patients have higher incidence of requiring cardiac surgery. Streptococcus gordonii belongs to the viridans group streptococci that are recognized as causative organisms for infective endocarditis particularly where dental sources are suspected. Patients with infective endocarditis may develop neurological sequelae including cerebrovascular accidents or central nervous system infections. If risk of haemorrhagic transformation is low, surgical intervention for valve replacement should not be delayed.

Enterococcal Infective Endocarditis – Post discharge treatment with continuous benzylpenicillin and ceftriaxone: A retrospective cohort study

BackgroundEnterococcal Infective Endocarditis (EIE) is usually treated with the combination of penicillin/ampicillin with gentamicin or ampicillin with ceftriaxone. To enable prolonged outpatient treatment, a combination of benzylpenicillin and ceftriaxone has been suggested. This study aimed to describe the incidence and characteristics of EIE and to determine the outcome of EIE cases treated with benzylpenicillin and ceftriaxone. MethodsThis was a retrospective single-center study including all patients diagnosed with infective endocarditis (IE) during 2016–2021, comparing EIE with IE caused by other pathogens. We described the outpatient treatment of patients with EIE, comparing those treated of benzylpenicillin - ceftriaxone with other regimes. ResultsAmong 222 patients with IE, 44 (20%) were diagnosed with EIE. Those were older, had a male predominance (p = 0.035), and were more disabled (p = 0.004). The incidence of EIE reached 30% towards the last year, becoming the leading etiology. Twenty-six patients received outpatient treatment, five of whom were discharged with benzylpenicillin and ceftriaxone. Adding patients from this cohort to the scarce data available, revealed similar recurrence and mortality rates compared to other treatment regimes. ConclusionsEIE is becoming a more frequent cause of IE, involving older, more disabled patients with male predominance. Our experience and existing literature suggest that the combination of benzylpenicillin and ceftriaxone is as safe as more conventional regimes, although further research is needed.

Abstract 18142: A Silent Heart Break: An Uncommon Case of Silent Mitral Valve Perforation Secondary to Infective Endocarditis

Introduction: Infective Endocarditis (IE) is an endocardial surface infection of the heart which may lead to valve damage and if severe, this may even lead to valve perforation which can cause significant regurgitation and cardiac function compromise. We present an uncommon case of IE complicated by mitral valve perforation. Case presentation: A 46-year old male with AIDS and polysubstance use was brought to the ED from a shelter after exhibiting erratic behavior with confusion. On exam, he was febrile and tachycardic. Lab data pertinent for lacticaemia and leukocytosis. Blood cultures grew Streptococcus Pneumoniae. MRI Brain was unremarkable. Echocardiography was unremarkable. Antibiotic was initiated leading to marked improvement in patient’s mental status. Despite clinical improvement, days into hospital course, a new holosystolic murmur was audible with left axillary radiation necessitating a repeat echocardiogram which revealed moderate-to-severe mitral eccentric jet regurgitation concerning for anterior leaflet perforation. He remained euvolemic without symptoms of heart failure and was subsequently transferred to a tertiary facility where a mitral valve surgery replacement was scheduled. Discussion: Most patients with infective endocarditis have no preceding valvular abnormality. This case is unusual as there was valvular perforation with no evidence of valvular involvement on prior imaging which could possibly be as a result of invasive streptococcus pneumonia IE potentially coexisting with bacterial meningitis which carries a high mortality rate. Invasive streptococcus pneumonia is an unusual cause of IE since wide availability of antibiotics and vaccines. This case reminds us of the need of thorough physical exam and sequential imaging in such immunocompromised patient groups. Conclusions: A high suspicion for mitral valve perforation should be maintained in patients with invasive streptococcus pneumoniae and new cardiac murmur.

Bartonella henselae mitral valve endocarditis associated with multi‐resistant Enterococcus faecalis bacteraemia in a cat

AbstractFeline infective endocarditis is a difficult condition to detect and diagnose early, with a poor long‐term prognosis. This case report describes the clinical, laboratory, instrumental and histological findings in a 12‐year‐old cat with Bartonella henselae endocarditis associated with multi‐resistant Enterococcus faecalis bacteraemia. The latter pathogen recently emerged as deadly nosocomial bacteria in humans and is considered a common cause of infective endocarditis. The prolonged corticosteroid therapy administered in the cat probably played a role in the onset of B. henselae endocarditis and E. faecalis intestinal translocation and bacteraemia. Echocardiography remains the tool of choice to suspect infective endocarditis, as it can detect vegetative lesions consistent with this condition. Feline infective endocarditis should always be considered as a differential diagnosis in cats, especially when there are signs of systemic disease, a history of prolonged corticosteroid treatment or concomitant infections.

Case series of 12 Bartonella quintana endocarditis from the Southwest Indian Ocean.

Bartonella spp. are fastidious bacteria frequently identified as the cause of blood culture-negative (BCN) endocarditis. However, Bartonella infections are difficult to diagnose in routine laboratory testing and their incidence is probably underestimated. We investigated the epidemiological and clinical features of Bartonella endocarditis cases diagnosed between 2009 and 2021 on Reunion Island (Southwest Indian Ocean). We retrospectively included all patients diagnosed with Bartonella endocarditis at Reunion Island University Hospital during this period. Endocarditis was diagnosed on the basis of microbiological findings, including serological tests (IFA) and PCR on cardiac valves, and the modified Duke criteria. We used then the multispacer typing (MST) method to genotype the available Bartonella strains. We report 12 cases of B. quintana endocarditis on Reunion Island (83.3% in men, median patient age: 32 years). All the patients originated from the Comoros archipelago. The traditional risk factors for B. quintana infection (homelessness, alcoholism, exposure to body lice) were absent in all but two of the patients, who reported head louse infestations in childhood. Previous heart disease leading to valve dysfunction was recorded in 50% of patients. All patients underwent cardiac valve surgery and antimicrobial therapy with a regimen including doxycycline. All patients presented high C-reactive protein concentrations, anemia and negative blood cultures. The titer of IgG antibodies against Bartonella sp. exceeded 1:800 in 42% of patients. Specific PCR on cardiac valves confirmed the diagnosis of B. quintana endocarditis in all patients. Genotyping by the MST method was performed on four strains detected in preserved excised valves and was contributive for three, which displayed the MST6 genotype. Bartonella quintana is an important cause of infective endocarditis in the Comoros archipelago and should be suspected in patients with mitral valve dysfunction and BCN from this area.

Treatment of Enterococcus faecalis Infective Endocarditis: A Continuing Challenge.

Today, Enterococcus faecalis is one of the main causes of infective endocarditis in the world, generally affecting an elderly and fragile population, with a high mortality rate. Enterococci are partially resistant to many commonly used antimicrobial agents such as penicillin and ampicillin, as well as high-level resistance to most cephalosporins and sometimes carbapenems, because of low-affinity penicillin-binding proteins, that lead to an unacceptable number of therapeutic failures with monotherapy. For many years, the synergistic combination of penicillins and aminoglycosides has been the cornerstone of treatment, but the emergence of strains with high resistance to aminoglycosides led to the search for new alternatives, like dual beta-lactam therapy. The development of multi-drug resistant strains of Enterococcus faecium is a matter of considerable concern due to its probable spread to E. faecalis and have necessitated the search of new guidelines with the combination of daptomycin, fosfomycin or tigecycline. Some of them have scarce clinical experience and others are still under investigation and will be analyzed in this review. In addition, the need for prolonged treatment (6-8 weeks) to avoid relapses has forced to the consideration of other viable options as outpatient parenteral strategies, long-acting administrations with the new lipoglycopeptides (dalbavancin or oritavancin), and sequential oral treatments, which will also be discussed.

Combinations of Daptomycin plus Ceftriaxone, but Not Ascending Daptomycin Dose-Regimens, Are Effective in Experimental Endocarditis Caused by Streptococcus mitis-oralis Strains: Target Tissue Clearances and Prevention of Emergence of Daptomycin-Resistance.

The Streptococcus mitis-oralis subgroup of the viridans group streptococci (VGS) are the most common cause of infective endocarditis (IE) in many parts of the world. These organisms are frequently resistant in vitro to standard β-lactams (e.g., penicillin; ceftriaxone [CRO]), and have the notable capacity for rapidly developing high-level and durable daptomycin resistance (DAP-R) during exposures in vitro, ex vivo, and in vivo. In this study, we used 2 prototypic DAP-susceptible (DAP-S) S. mitis-oralis strains (351; and SF100), which both evolved stable, high-level DAP-R in vitro within 1 to 3 days of DAP passage (5 to 20 μg/mL DAP). Of note, the combination of DAP + CRO prevented this rapid emergence of DAP-R in both strains during in vitro passage. The experimental rabbit IE model was then employed to quantify both the clearance of these strains from multiple target tissues, as well as the emergence of DAP-R in vivo under the following treatment conditions: (i) ascending DAP-alone dose-strategies encompassing human standard-dose and high-dose-regimens; and (ii) combinations of DAP + CRO on these same metrics. Ascending DAP-alone dose-regimens (4 to 18 mg/kg/d) were relatively ineffective at either reducing target organ bioburdens or preventing emergence of DAP-R in vivo. In contrast, the combination of DAP (4 or 8 mg/kg/d) + CRO was effective at clearing both strains from multiple target tissues (often with sterilization of bio-burdens in such organs), as well as preventing the emergence of DAP-R. In patients with serious S. mitis-oralis infections such as IE, especially caused by strains exhibiting intrinsic β-lactam resistance, initial therapy with combinations of DAP + CRO may be warranted.

Cardiobacterium hominis Endocarditis in a Healthy Adult - Rare but Not to Be Missed

Cardiobacterium hominis is part of HACEK group and an atypical cause of infective endocarditis. It may cause similar clinical presentation to other cause of endocarditis. Establishing the diagnosis is challenging as it is a fastidious organism which rarely affects individual without previous cardiac lesion and requires advanced diagnostic tools for identification of species. A 23-year-old previously healthy man presented with intermittent fever for two months associated with palpitations and lethargy. He had undergone a dental procedure four months before the presenting symptoms. Physical examination revealed a pansystolic murmur best heard over the apex. Three aerobic blood culture bottles were positive and Gram stain consistently showed pleomorphic Gram-negative rods. The organism grew as tiny pin-point opaque colonies on sheep blood agar and chocolate agar after 48 hours of incubation but no growth was seen on MacConkey agar. Unsuccessful identification with VITEK 2 NH and VITEK 2 GN was later confirmed by polymerase chain reaction as C. hominis. He was treated with a six-week course of antibiotics.

Species and biotypes of Streptococcus bovis causing infective endocarditis

IntroductionStreptococcus bovis/equinus complex (SBEC) is a major cause of infective endocarditis (IE), although its incidence varies greatly depending on the geographical area. The characteristics of IE caused by Streptococcus gallolyticus susp. gallolyticus are well known; there are hardly any descriptions of IE caused by other species or biotypes. MethodsRetrospective cohort study, from 1990 to 2019, of all SBEC IE in adults in three Spanish hospitals, Lugo (LH), Barcelona (BH) and Ferrol (FH) where the population is mainly rural, urban and mixed, respectively. The incidence of IE was analyzed in 3 areas. Clinical characteristics of IE (277 cases, 258 biotyped) were compared according to SBEC species and biotypes. ResultsThere are significant differences between the incidence of SBEC IE in HL (27.9/106) vs. HF and HB (8.8 and 7,1, respectively, p<0.001). We found significant differences (SbI vs. SbII) in mean age (68.5 vs. 73 years; p<0.01), duration of symptoms before diagnosis (46.9±46.5 vs. 30.4±40.9 days; p<0.01), presence of comorbidities: 39.1% (78) vs. 54.2% (32; p<0.04), predisposing heart illness:62.3% (124) vs. 81.3% (48; p<0.006), particularly, prosthetic or intravascular devices IE: 24.6% (49) vs. 52.4% (31; p<0.001), bi-valve involvement:23.6% (47) vs. 11.8% (7; p<0.05) and heart failure: 24.6% (49) vs. 38.9% (23; p<0.03). There were no significant differences in embolic events, need for surgery or mortality. The association with CRC was high in both groups: 77.7% vs. 66.6%. ConclusionsIE due to SBEC has geographical variations in incidence and different clinical characteristics among biotypes. The association with CRC was high.

Complex pathogens in infective endocarditis

Infective endocarditis (IE) is a complex disease whose prognosis depends on the causative microorganism, among other factors. The latter can be difficult to identify and/or treat. In this narrative review, we identify knowledge gaps in the diagnosis and antimicrobial treatment of IE, and attempt to shed light on current questions. Specifically, we: (1) analyze the factors that may hinder the microbiological diagnosis of blood culture-negative IE, as well as the role of new imaging techniques, such as 18F-fluorodeoxyglucose ([18F]FDG PET/CT), in the diagnostic capacity of this disease, understanding their advantages and assuming their limitations; (2) discuss the therapeutic approach to various difficult-to-treat microorganisms. In particular, we focus on the treatment of staphylococcal IE since, at present, staphylococci are the most frequent cause of IE in developed countries and staphylococcal IE is one of those with the highest short- and long-term mortality. We critically evaluate the current evidence on combination therapy and address the occurrence of serious side effects, an aspect that is often overlooked owing to the severity of the infection; and (3) emphasize the need for home antimicrobial treatment of patients with IE, as these are fragile people who benefit from an early return to their environment. This poses undoubted logistical challenges and requires robust evidence to ensure the best short- and long-term outcomes.

1988. Piperacillin-tazobactam plus Ceftriaxone for Enterococcus faecalis endocarditis: A Single Center Experience

Abstract Background Enterococcus faecalis is a leading cause of Infective Endocarditis (IE). IE guidelines recommend combination of penicillin (PCN) or ampicillin (AMP) with ceftriaxone (CTX) in susceptible strains. OPAT allows for antibiotic continuation at home; however outpatient AMP is limited due to frequent dosing and instability. Piperacillin-tazobactam (PTZ) has similar but not identical activity against penicillin binding proteins (PBP) compared to AMP and PCN, suggesting that PTZ may be a substitute in OPAT. This study compares outcomes in those with E. faecalis IE discharged with either PTZ or PCN with CTX. Results of primary outcomes including death at 90 days and readmission at 90 days for those discharged on either PTZ or PCN in combination with CTX for E. faecalis endocarditis Results of non infectious complications and changes in antibiotic therapy in both groups post discharge Methods This single center retrospective study took place from 2016 - 2020. Adults &amp;gt; 18 years with AMP susceptible E. faecalis IE diagnosed using Duke’s criteria and blood or tissue cultures were included, with cultures confirming PCN susceptibility. Primary endpoint was failure of therapy at 90 days, defined as death due to any cause or infection relapse. Secondary outcomes were duration of antibiotics, change in regimen and non-infectious complications. Results Overall, 34 patients were identified, 17 in each group. Average age was 60–80 years, majority having a high Charleston comorbidity index. One did not have available AMP susceptibility but was PCN susceptible. 19 were managed surgically (65% PTZ group, 47% PCN group). Average total antibiotic course was 8.2 and 7.3 weeks in PTZ and PCN groups, with average OPAT course being 4.5 and 4.4 weeks. Primary endpoint was met in 18% patients in the PTZ group and 24% in the PCN group. Of the PCN group, 1 was admitted 4 months later due to an E. faecalis device infection, outside of primary endpoint. Nearly 80% completed antibiotic therapy with 29% in the PTZ group and 35% in the PCN group readmitted for non-infectious complications, including metabolic imbalances, stroke, volume overload and gastro-intestinal bleed. Hyperkalemia was seen in the PCN group with 3 patients requiring readmission. Seizures were not reported with combined PCN and ceftriaxone. Conclusion Similar outcomes were seen using either PTZ or PCN with CTX for treatment of enterococcal IE. Discharging patients on PCN is not always a feasible option. In these instances, PTZ could be considered as an alternative OPAT agent despite dissimilar mechanism of action compared to AMP and PCN. Disclosures All Authors: No reported disclosures.

1980. A Case Series of Serratia Marcescens Endocarditis in Persons Who Inject Drugs

Abstract Background Serratia marcescens is a gram-negative bacillus that is widespread in the environment and has been recognized as a rare cause of infective endocarditis (IE), particularly in persons who inject drugs (PWID). The literature consists of a 19 person case series in the 1970s followed by just a handful of case reports and small case series. At AHWFB (Atrium Health Wake Forest Baptist), we have noticed an increasing number of severe infections, including IE, with Serratia marcescens in PWID. Methods We conducted a retrospective chart review of all cases of Serratia grown from sterile culture sites in the AHWFB system between 8/1/2016 -10/31/2021. Charts were reviewed to confirm status of injection drug use in the 3 months prior to admission, ≥18 years old, and possible or definite IE by Modified Duke’s criteria. Results Twenty two participants were included in the study. The median age was 29.5 years. Eighteen (90%) were white and 16 (73%) were female. Sixteen (73%) had injection of opioids and 3 (14%) had injection of stimulants clearly indicated. Ten (45.5%) had stimulant use documented but the route was not clear. Nineteen (95%) had evidence of active or resolved HCV infection. The median duration of bacteremia was 2 days. Two cases of IE involved the aortic valve, 8 mitral, 3 pulmonic, and 10 tricuspid. Four (18%) of the participants had prosthetic valve IE. Nine (41%) of the participants had a history of previous IE episode. Eighteen participants had evidence of septic emboli: 10 pulmonary, 7 cerebral, and 5 major arterial. In terms of disposition, 4 (18%) patients died, 4 left against medical advice, 12 (54%) remained at a facility for the duration of their antibiotics. One patient was transferred to another facility and one was discharged to complete antibiotic therapy via peripheral IVs in an infusion center. Two patients expired before a final antibiotic regimen could be determined. Ten participants were treated with beta lactam monotherapy, 1 with fluoroquinolone monotherapy, and 9 with dual therapy with a beta lactam and fluoroquinolone. Conclusion Serratia marcescens, a rare cause of IE, has been found in a population of PWID in a North Carolina hospital system. More research is necessary to understand why this unusual infection is clustering in this population and the optimal treatment regimen. Disclosures All Authors: No reported disclosures.

Granulicatella adiacens infective endocarditis

Infective endocarditis is an unconventional infectious disease nonetheless life-threatening. A roundabout of 3% to 5% cases of Streptococcal infective endocarditis is caused by nutritionally variant Streptococci (NVS). Granulicatella species is one of the atypical causes of infective endocarditis. In this context, the authors are disclosing a case of infective endocarditis in an underlying rheumatic heart disease patient, caused by Granulicatella adiacens. The patient had breathlessness for the past four months, on and off fever for two months anew and mid-diastolic murmur with vegetation in aortic valve as appeared by echocardiogram. The blood cultures were tested positive for Granulicatella adiacens. The patient was successfully treated with intravenous vancomycin for a period of six weeks.

Platelet Activation and Aggregation Induced by Streptococcus bovis/Streptococcus equinus Complex.

Streptococcus bovis/Streptococcus equinus complex (SBSEC) is a common cause of infective endocarditis (IE). For IE-pathogens, the capacity to activate and aggregate platelets is believed to be an important virulence mechanism. While the interactions between bacteria and platelets have been described in detail for many Gram-positive pathogens, little research has been carried out with SBSEC in this respect. Twenty-six isolates of the four most common species and subspecies of SBSEC identified in bacteremia were collected, and interactions with platelets were investigated in platelet rich plasma (PRP) from three donors. Aggregation was studied using light-transmission aggregometry and platelet activation using flow cytometry detecting surface upregulation of CD62P. Platelets and serum were treated with different inhibitors to determine mechanisms involved in platelet aggregation and activation. Twenty-two of 26 isolates induced aggregation in at least one donor, and four isolates induced aggregation in all three donors. In PRP from donor 1, isolate SL1 induced a rapid aggregation with a median time of 70 s to reach 50% aggregation. Blockade of the platelet Fc-receptor or enzymatic cleavage of IgG abolished platelet activation and aggregation. The capacity for bacteria-induced platelet aggregation was also shown to be transferable between donors through serum. SBSEC mediates platelet aggregation in an IgG and IgG-Fc-receptor dependent manner. Bacterial activation of platelets through this pathway is common for many bacteria causing IE and could be a potential therapeutic target for the prevention and treatment of this infection. IMPORTANCE The capacity of bacteria to activate and aggregate platelets is believed to contribute to the pathogenesis of IE. The Streptococcus bovis/Streptococcus equinus complex (SBSEC) contains known IE-pathogens, but there is limited research on the different subspecies ability to interact with platelets and what signaling pathways are involved. This study reports that 22 of 26 tested isolates of different subspecies within SBSEC can induce aggregation, and that aggregation is host dependent. The Fc-IgG-receptor pathway was shown essential for platelet activation and aggregation. To the best of our knowledge, this is the first study that reports on platelet interactions of SBSEC-isolates other than Streptococcus gallolyticus subspecies gallolyticus as well as the first study to report of mechanisms of platelet interaction of SBSEC-isolates. It adds SBSEC to a group of bacteria that activate and aggregate platelets via the platelet Fc-receptor. This could be a potential therapeutic target for prevention of IE.