Microbiological etiology in prosthetic valve endocarditis : A nationwide registry study

Background: Prosthetic valve endocarditis (PVE) is a feared complication after heart valve surgery. Studies on differences in bacteriology in various types of PVE are limited. Objectives: This study aimed to investigate the microbiology of PVE depending on the type of prosthetic valve and timing of diagnosis. Methods: A retrospective study based on the Swedish Registry on Infective Endocarditis focusing on PVE was conducted. The cohort was divided into mechanical and bioprosthetic valves; into endocarditis localization in the aortic, mitral, or tricuspid valve; and into early and late PVE. The microbiology in these groups was compared. Predictors of Staphylococcus aureus as the cause of PVE were examined by multivariable logistic regression. Results: A total of 780 episodes of PVE in 749 patients were compared regarding the distribution of causative microbiological agents. The most common agents included alpha-hemolytic streptococci (29%), S. aureus (22%), enterococci (14%), coagulase-negative staphylococci (CoNS) (12%), and Cutibacterium acnes (6%). S. aureus was more commonly found on mechanical valves compared to bioprosthetic ones (36% vs. 17%, p < 0.001) whereas alpha-hemolytic streptococci, enterococci, and CoNS were more common on bioprosthetic valves. There were no significant differences in the microbiology of PVE affecting mitral or aortic valves or in cases of early and late PVE. Predictors for S. aureus as the cause of PVE were end-stage renal disease, intravenous drug use, mechanical valve, and tricuspid localization of endocarditis. Conclusions: The type of prosthetic heart valve is associated with the causative pathogen. Patients with mechanical valves are more likely to have PVE caused by S. aureus

Clinical and microbiological features of infective endocarditis caused by aerococci.

To define the clinical presentation of aerococcal infective endocarditis (IE) and the prevalence of synergy between penicillin and gentamicin on aerococcal isolates

Comparing right- and left sided injection-drug related infective endocarditis

The aim of the study was to compare background characteristics, microbiology and outcome of patients with right-sided and left-sided intravenous drug use (IDU) associated infective endocarditis (IE). A nationwide retrospective study using the Swedish Registry on Infective Endocarditis between 2008 and 2019 was conducted. A total of 586 people with IDU-IE were identified and divided into left-sided (n = 204) and right-sided (n = 382) IE. Descriptive statistics, Cox-regression and Kaplan–Meier survival estimates were used. The mean age of patients in the left-sided group was 46 years compared to 35 years in the right-sided group, p < 0.001. Left-sided IE had a higher proportion of females. Staphylococcus aureus was the causative pathogen in 48% of cases in the left-sided group compared to 88% in the right-sided group. Unadjusted and adjusted long-term survival was better in right-sided IE compared to left-sided IE. Independent predictors of long-term mortality were increasing age, end-stage renal disease, nosocomial infection, brain emboli and left-sided IE. Left-sided IE was common in people with IDU but the proportion of females with left-sided IE was low. S. aureus was twice as common in right-sided IE compared to left-sided IE, and the long-term prognosis of right sided IDU-associated IE was better compared to left-sided IE despite the fact that few were operated

Infective Endocarditis Due to Corynebacterium Species : Clinical Features and Antibiotic Resistance

Background: Corynebacterium species are often dismissed as contaminants in blood cultures, but they can also cause infective endocarditis (IE), which is a severe condition. Antibiotic resistance of corynebacteria is increasing making treatment challenging. Reports on IE caused by Corynebacterium species are scarce and more knowledge is needed. Methods: Cases of IE caused by Corynebacterium species were identified through the Swedish Registry of Infective Endocarditis. Isolates were collected for species redetermination by matrix-assisted laser desorption ionization-time of flight and for antibiotic susceptibility testing using Etests. Results: Thirty episodes of IE due to Corynebacterium species were identified between 2008 and 2017. The median age of patients was 71 years (interquartile range, 60-76) and 77% were male. Corynebacterium striatum (n = 11) was the most common IE causing pathogen followed by Corynebacterium jeikeium (n = 5). Surgery was performed in 50% and in-hospital mortality rate was 13%. Patients with IE caused by Corynebacterium species were significantly more likely to have prosthetic valve endocarditis (70%), compared with patients with IE due to Staphylococcus aureus or non-beta-hemolytic streptococci (14% and 26%, respectively) (P <. 0001). Vancomycin was active towards all Corynebacterium isolates, whereas resistance towards penicillin G was common. Conclusions: Corynebacterium species cause IE, where prosthetic valves are mainly affected and surgery is often performed. Corynebacterium striatum is an important causative agent of IE within the genus. Antibiotic resistance of corynebacteria is relatively common but resistance towards vancomycin could not be detected in vitro

Prosthetic valve endocarditis caused by Propionibacterium species : a national registry-based study of 51 Swedish cases

Propionibacterium spp. are a rare cause of infective endocarditis (IE). The diagnosis is difficult because the bacteria are slow-growing and growth in blood cultures is often misinterpreted as contamination from the skin flora. The aim of this study was to describe all cases of Propionibacterium spp. endocarditis in the Swedish national registry of IE. The registry was searched for all cases of IE from 1995 to 2016 caused by Propionibacterium spp. Data concerning clinical characteristics, treatment, and outcome were registered. A total of 51 episodes of definitive prosthetic valve endocarditis (PVE) caused by Propionibacterium spp. were identified, comprising 8% of cases of PVE during the study period. Almost all cases (n = 50) were male. The median time from surgery to diagnosis of IE was 3 years. Most patients were treated mainly with beta-lactams, partly in combination with aminoglycosides. Benzyl-penicillin was the most frequently used beta-lactam. A total of 32 patients (63%) underwent surgery. Overall, 47 patients (92.1%) were cured, 3 (5.9%) suffered relapse, and 1 (2.0%) died during treatment. IE caused by Propionibacterium spp. almost exclusively affects men with a prosthetic valve and findings of Propionibacterium spp. in blood cultures in such patients favors suspicion of a possible diagnosis of IE. In patients with prosthetic valves, prolonged incubation of blood cultures up to 14 days is recommended. The prognosis was favorable, although a majority of patients required cardiac surgery during treatment. Benzyl-penicillin should be the first-line antibiotic treatment option for IE caused by Propionibacterium spp

Infective endocarditis due to Streptococcus dysgalactiae : clinical presentation and microbiological features

Knowledge of infective endocarditis (IE) caused by Streptococcus dysgalactiae (SD) is limited. This study aimed to identify the clinical and microbiological features of SD-caused IE and to investigate any possible synergy between penicillin and gentamicin on SD isolates. Cases of IE 2008–2016 due to SD reported to the Swedish Registry of Infective Endocarditis (SRIE) were identified. Isolates were emm typed and synergy between antibiotics was determined in time-kill experiments. Medical records were reviewed and SD-cases were compared to cases of IE due to other pathogens reported to the SRIE. Fifty cases of SD-caused IE were confirmed. emm types stC74a, stG62647, and stG643 were most commonly encountered. The patients had a median age of 74 years (range 38–93) and were significantly older compared to patients with Staphylococcus aureus-caused IE, (65 years (p = 0.003)). The median time to diagnosis from symptom onset was 1 day for patients with SD-caused IE which was less compared to patients with IE due to the other pathogens (2–15 days). Embolization was seen in 46% and the in-hospital mortality was 8%. Etest-based methods did not indicate any synergy between penicillin and gentamicin whereas synergy was noted for four out of nine isolates applying time-kill assays. This is the largest study of SD-caused IE, a condition with an acute onset predominantly affecting elderly people. Synergy between penicillin and gentamicin against some SD isolates was distinguished but the potential benefit of this must be weighed against the risk of aminoglycoside side effects

Infective endocarditis caused by HACEK group bacteria—a registry-based comparative study

Infective endocarditis (IE) caused by bacteria within Haemophilus (excluding Haemophilus influenzae), Aggregatibacter, Cardiobacterium, Eikenella and Kingella (HACEK) is rare. This study aimed to describe clinical features of IE caused by HACEK genera in comparison with IE due to other pathogens. Cases of IE due to HACEK were identified through the Swedish Registry of Infective Endocarditis (SRIE). Clinical characteristics of IE cases caused by HACEK were compared with cases of IE due to other pathogens reported to the same registry. Ninety-six patients with IE caused by HACEK were identified, and this corresponds to 1.8% of all IE cases. Eighty-three cases were definite endocarditis, and the mortality rate was 2%. The median age was 63 years, which was lower compared to patients with IE caused by other pathogens (66, 70 and 73 years respectively, p ≤ 0.01). Patients with IE caused by Haemophilus were younger compared to patients with IE due to Aggregatibacter (47 vs 67 years, p ≤ 0.001). Patients with IE due to HACEK exhibited longer duration from onset of symptoms to hospitalization and had more prosthetic valve endocarditis compared to patients with IE due to Staphylococcus aureus (10 vs 2 days, p ≤ 0.001, and 35 vs 14%, p ≤ 0.001). This is, to date, the largest study on IE due to HACEK. Aggregatibacter was the most common cause of IE within the group. The condition has a subacute onset and often strikes in patients with prosthetic valves, and the mortality rate is relatively low

Native aortic versus mitral valve infective endocarditis : A nationwide registry study

Background Native aortic and mitral valve infective endocarditis (AVE and MVE, respectively) are usually grouped together as left-sided native valve infective endocarditis (LNVE), while the differences between AVE and MVE have not yet been properly investigated. We aimed to compare AVE and MVE in regard to patient characteristics, microbiology and determinants of survival. Methods We conducted a retrospective study using the Swedish national registry on infective endocarditis, which contains nationwide patient data. The study period was 2007-2017, and included cases were patients who had either AVE or MVE. Results We included 649 AVE and 744 MVE episodes. Staphylococcus aureus was more often the causative pathogen in MVE (41% vs 31%, p<0.001), whereas enterococci were more often the causative pathogen in AVE (14% vs 7.4%, p<0.001). Perivalvular involvement occurred more frequently in AVE (8.5% vs 3.5%, p<0.001) and brain emboli more frequently in MVE (21% vs 13%, p<0.001). Surgery for IE was performed more often (35% vs 27%, p<0.001) and sooner after diagnosis (6.5 days vs 9 days, p=0.012) in AVE than in MVE. Several risk predictors differed between the two groups. Conclusions The microbiology seems to differ between AVE and MVE. The causative pathogen was not associated with mortality in AVE. The between-group differences regarding clinical presentation and predictors of survival indicate that it may be important to differentiate AVE from MVE in the treatment of LNVE