Infective endocarditis by Acinetobacter species: a systematic review

Isolated pulmonary valve endocarditis in a pediatric patient with down syndrome

BACKGROUND

Isolated pulmonary valve endocarditis (IPE) accounts for less than 2% of all infective endocarditis patients. It is commonly associated with several predisposing factors, including intravenous drug use (IVDU) and congenital heart disease. The most common causative pathogens of IPE are Staphylococcus aureus and Streptococcus viridans. We report a Down's syndrome patient with IPE and with no standard risk factors caused by the rare pathogen Acinetobacter spp. This led to respiratory failure and systemic infection due to septic pulmonary emboli. Early elective surgery was decided upon as the patient was no longer responding to medical therapy, and his clinical condition was worsening over time.

CASE PRESENTATION

A 15-year-old male with Down syndrome and no underlying heart defect presented with a 3-month history of episodic fever, nausea, vomiting, and diarrhea. Transthoracic echocardiography (TTE) revealed large vegetation on the pulmonary valve leaflet, another mobile mass at the pulmonary artery bifurcation, and severe pulmonary regurgitation. Serial blood cultures isolated Acinetobacter spp. Despite initial antibiotic therapy, the patient continued to have sepsis, unresolved vegetations, and developed life-threatening complications and respiratory distress, which convinced us to perform a pulmonary valve replacement surgery with a homograft. After surgery, the patient recovered and was discharged on the ninth postoperative day (POD).

CONCLUSION

This report highlights IPE's diagnostic and therapeutic challenges, alongside the importance of a comprehensive cardiopulmonary workup in patients with unexplained fever, sepsis, and pulmonary symptoms, even without typical risk factors. Based on the patient's aggravating condition despite medical treatment, early surgical intervention and pulmonary valve replacement were deemed crucial. However, there still needs to be a definitive guideline on when and how surgery should be performed in patients with complicated IPE, especially in pediatric patients.

Infective Endocarditis by Campylobacter Species-A Narrative Review

Infective endocarditis (IE) is a disease that may cause significant morbidity and mortality. IE is classically caused by Gram-positive microorganisms; however, Gram-negative bacteria may seldom also be the cause. Campylobacter species cause zoonosis and may also infect humans, mainly causing gastrointestinal infection by C. jejuni or invasive disease by C. fetus, such as bacteremia, sepsis, meningitis, or vascular infection. Campylobacter species IE has rarely been described, and most reports are cases and/or case series. Thus, the characteristics of this disease, including its epidemiology, clinical presentation, treatment, and outcome, remain largely unknown. This study aimed to review all published Campylobacter IE cases and describe their characteristics. A thorough search of PubMed, the Cochrane Library, and Scopus for published studies providing information on epidemiology, clinical findings, treatment, and outcome of Campylobacter IE cases was performed for the present narrative review. A total of 22 studies containing data from 26 patients were located and included. Among all patients, 73.1% were male; the median age was 65 years. Among all patients, 36.4% had a history of a prosthetic valve. The most commonly affected valve was the aortic, followed by the mitral. Fever, heart failure, and sepsis were the most frequent clinical findings. The most commonly isolated pathogen was C. fetus, with only one patient having C. jejuni IE. Antimicrobial resistance was low for all antimicrobials, with tetracycline having the highest resistance. Aminoglycosides and beta-lactams were the most commonly used antimicrobials. Surgery was performed in 48% of patients. The mortality rate was 26.9%. Patients who died were more likely to have sepsis, shock, and heart failure and were less likely to have been treated with aminopenicillins; however, no factor was identified in a multivariate logistic regression model as an independent factor for overall mortality.

Uncommon pathogens causing infective endocarditis

Infective endocarditis is caused by a wide range of aetiological agents. The microbiology, epidemiology, and treatment of this disease have changed considerably in the last two decades. Staphylococci and streptococci are known to be the classical causative agents; however, blood culture-negative endocarditis caused by fastidious and slow-growing organisms is now common. The list of uncommon pathogens causing endocarditis has expanded in recent years. This is a narrative literature review of the aetiological agents of endocarditis that are rarely encountered in clinical practice, their epidemiology, the characteristics of these pathogens, the clinical presentations of the cases, and their management.

Acinetobacter radioresistens and Microbacterium paraoxydans endocarditis in patient with indwelling catheter and metastatic carcinoma

Acinetobacter radioresistens is a rare cause of nosocomial infection and is believed to confer antibiotic resistance to aggressive bacterial species. We present the first reported case of polymicrobial endocarditis caused by A. radioresistens and Microbacterium paraoxydans co-infection, a case of a woman in her late 60s with bacteraemia and ultimate finding of endometrial carcinoma. Bacteraemia with either agent in a previously healthy patient should prompt providers to search for underlying malignancy or immunological problem.We support the use of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry for identifying these organisms in cultures, as well as the development of faster isolation techniques through PCR. Furthermore, we advocate for providers to order early antibiotic susceptibility testing, since our patient's Microbacterium sp was not susceptible to meropenem unlike most Microbacterium reported in literature.

Atmospheric microplastics: exposure, toxicity, and detrimental health effects

Microplastics (MPs) are micro-particulate pollutants present in all environments whose ubiquity leads humans to unavoidable exposure. Due to low density, MPs also accumulate in the atmosphere, where they are easily transported worldwide and come into direct contact with the human body by inhalation or ingestion, causing detrimental health effects. This literature review presents the sources of atmospheric MPs pollution, transport routes, physicochemical characteristics, and environmental interactions. The document also explains the implications for human health and analyzes the risk of exposure based on the potential toxicity and the concentration in the atmosphere. MPs' toxicity lies in their physical characteristics, chemical composition, environmental interactions, and degree of aging. The abundance and concentration of these microparticles are associated with nearby production sources and their displacement in the atmosphere. The above elements are presented in an integrated way to facilitate a better understanding of the associated risk. The investigation results encourage the development of future research that delves into the health implications of exposure to airborne MPs and raises awareness of the risks of current plastic pollution to promote the establishment of relevant mitigation policies and procedures.

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%.

Variations in the fecal microbiota and their functions of Thoroughbred, Mongolian, and Hybrid horses

The horse gut is colonized by a rich and complex microbial community that has important roles in horse physiology, metabolism, nutrition, and immune functions. Fewer across-breed variations in horse gut microbial diversity have been illustrated. In this article, the gut microbiota of Thoroughbred, Mongolian, and Hybrid horses [first filial generation (F1) of Mongolian (maternal) and Thoroughbred (paternal)] were studied by second-generation high-throughput sequencing technology. Differences in gut microbiota composition and function between breeds were determined using diversity and functional prediction analysis. The alpha diversity analysis showed that Thoroughbred horses had a more abundant and diverse gut microbiota, while the diversity of gut microbiota in Hybrid horses was intermediate between Thoroughbred and Mongolian horses. Subsequent cluster analysis showed that Hybrid horses have a microbiota composition more similar to Mongolian horses. LEfSe analysis revealed that the bacterial biomarkers for Thoroughbred horses at the family level were Prevotellaceae, Rikenellaceae, Fibrobacteraceae, p_251_o5, Lactobacillaceae, and uncultured_bacterium_o_WCHB1_41; the bacterial biomarker for Mongolian horses was Planococcaceae; and the bacterial biomarkers for Hybrid horses were Moraxellaceae, Enterobacteriaceae, and Ruminococcaceae. The functional prediction results indicated that the metabolic pathways differ significantly between the breeds. Regarding metabolism, the Hybrid horses had the lowest proportion of the carbohydrate metabolic pathways, while the energy metabolic pathway had the highest proportion. The abundance ratios of the remaining eight metabolic pathways in Hybrid horses were between Thoroughbred and Mongolian horses. In conclusion, the results of this study showed an association between horse breeds and gut microbiota.

Infective endocarditis by Actinomyces species: a systematic review

Actinomycosis, is a slowly progressive infection that may mimic malignancy due to the invasiveness of tissues and the ability to form sinus tracts. Infective Endocarditis (IE) is a rare disease with significant morbidity and mortality. Interestingly, even though there are scarce data of IE by Actinomyces spp. in the literature, a review adequately summarizing all available evidence on the topic in a systematic way is lacking. The aim of this study was to systematically review all cases of IE by Actinomyces spp. in the literature and describe the epidemiology, microbiology, clinical characteristics, treatment and outcomes of this infection. A systematic review of PubMed, Scopus and Cochrane library (through 19 August 2021) for studies providing epidemiological, clinical, microbiological as well as treatment data and outcomes of IE by Actinomyces spp. was performed. A total of 31 studies providing data for 31 patients were included. A prosthetic valve was present in 12.9%, while the most common microorganism was A. meyeri. Aortic valve was the most commonly infected intracardiac site, followed by the mitral valve. Diagnosis was most commonly performed with transesophageal echocardiography, while the diagnosis was made at autopsy in 16.1%. Penicillin, cephalosporins and aminopenicillins were the most commonly used antimicrobials. Clinical cure was noted in 80.6%, while mortality was 19.4%. Development of heart failure was associated with mortality by IE. This systematic review thoroughly describes IE by Actinomyces and provides information on epidemiology, clinical presentation, treatment and outcomes.

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%.

Sequelae of Infective Endocarditis: Ruptured Aortic Root Abscess in a 38-Year-Old Female With Complicated Infective Endocarditis

A 38-year-old female with no known comorbidities or previous history of heart disease presented to the hospital with a three-day history of drowsiness and shortness of breath. Transthoracic echocardiography was performed, which showed large vegetations on aortic and tricuspid valves. In addition, there was severe aortic regurgitation with a possible abscess on the non-coronary cusp of the aortic valve.

The patient was admitted, and a provisional diagnosis of disseminated tuberculosis, Infective endocarditis (IE), and sepsis was made. Surgical intervention was planned. Intraoperative findings revealed that a fistula had formed connecting the aorta and right atrium, which was closed with an autologous graft derived from the patient’s pericardial tissue. Vegetations were removed, and the aortic valve was replaced with a metallic valve.

This case report presents a patient with complicated IE with a ruptured aortic root abscess. Mechanical complications associated with IE, such as in our case, are rare among patients with IE. However, surgical intervention should be considered as an option in complicated cases of IE when standard therapy fails.

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.

Acinetobacter radioresistens and Enterococcus casseliflavus co-infection with endocarditis, bacteremia, and pneumonia

Acinetobacter species are Gram-negative coccobacilli found to cause a multitude of infections. However, they are a rare cause of bacteremia with Acinetobacter radioresistens accounting for less than 10 % of Acinetobacter infections. In this report, we describe a patient presenting with acute encephalopathy, fever, and hypoxia who was initially found to have bilateral perihilar and lower lobar peribronchial thickening on chest x-ray. Two sets of blood cultures obtained on admission were positive for Acinetobacter radioresistens and Enterococcus casseliflavus and one set of blood cultures returned positive for Leclercia adecarboxylata although believed to be a skin contaminant. Susceptibilities confirmed all bacteria were pan-sensitive. The patient was also found to have an aortic valve vegetation which was not amenable to surgical intervention. He was treated with 42 days of daptomycin and cefepime. At present, co-infection with Acinetobacter radioresistens and Enterococcus casseliflavus with manifestations of polymicrobial endocarditis has never been reported. Though this co-infection was pan-sensitive, there is an increasing rate of resistance to commonly used, broad-spectrum antibiotics such as β-lactams, which will continue to pose a challenge between balancing treatment and antibiotic stewardship.

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.

Acinetobacter baumannii Infections in Hospitalized Patients, Treatment Outcomes

Background Acinetobacter baumannii (AB), an opportunistic pathogen, could develop into serious infections with high mortality and financial burden. The debate surrounding the selection of effective antibiotic treatment necessitates studies to define the optimal approach. This study aims to compare the clinical outcomes of commonly used treatment regimens in hospitalized patients with AB infections to guide stewardship efforts. Material and methods: Ethical approval was obtained, 320 adult patients with confirmed AB infections admitted to our tertiary care facility within two years were enrolled. The treatment outcomes were statistically analyzed to study the relation between antibiotic regimens and 14, 28, and 90-day mortality as the primary outcomes using binary logistic regression—using R software—in addition to the length of hospitalization, adverse events due to antibiotic treatment, and 90-day recurrence as secondary outcomes. Results: Among 320 patients, 142 (44%) had respiratory tract, 105 (33%) soft tissue, 42 (13%) urinary tract, 22 (7%) bacte iemia, and other infections 9 (3%). Nosocomial infections were 190 (59%) versus community-acquired. Monotherapy was significantly associated with lower 28-day (p < 0.05, OR:0.6] and 90-day (p < 0.05, OR:0.4) mortality rates, shorter length of stay LOS (p < 0.05, Median: −12 days] and limited development of adverse events (p < 0.05, OR:0.4). Subgroup analysis revealed similar results ranging from lower odds of mortality, adverse events, and shorter LOS to statistically significant correlation to monotherapy. Meropenem (MEM) and piperacillin/tazobactam (PIP/TAZ) monotherapies showed non-significant high odd ratios of mortalities, adverse events, and disparate LOS. There was a statistical correlation between most combined therapies and adverse events, and longer LOS. Colistin based and colistin/meropenem (CST/MEM) combinations were superior in terms of 14-day mortality (p = 0.05, OR:0.4) and (p < 0.05, OR:0.4) respectively. Pip/Taz and MEM-based combined therapies were associated with statistically non-significant high odd ratios of mortalities. Tigecycline (TGC)-based combinations showed a significant correlation to mortalities (p < 0.05, OR:2.5). Conclusion: Monotherapy was associated with lower mortality rates, shorter LOS, and limited development of adverse events compared to combined therapies. Colistin monotherapy, colistin/meropenem, and other colistin combinations showed almost equivalent mortality outcomes. Patients on combined therapy were more susceptible to adverse events and comparable LOS. The possible adverse outcomes of PIP/TAZ and MEM-based therapies in the treatment of MDRAB infections and the association of TGC with a higher mortality rate raise doubts about their treatment role.

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.