Influence of referral bias on the apparent clinical spectrum of infective endocarditis

The hidden side of infective endocarditis: Diagnostic and management of 500 consecutive cases in noncardiac surgery centers (2009-2018)

BACKGROUND

We aimed to describe infective endocarditis cases from noncardiac surgery centers, as current knowledge on infective endocarditis is derived mostly from cardiac surgery hospitals.

METHODS

An observational retrospective study (2009-2018) was conducted in 9 noncardiac surgery hospitals in Central Catalonia. All adult patients diagnosed with definitive infective endocarditis were included. Transferred and nontransferred cohorts were compared, and a logistic regression model was used to ascertain the prognostic factors.

RESULTS

Overall, 502 infective endocarditis episodes were included: 183 (36.5%) were transferred to the cardiac surgery center, whereas 319 were not, with (18.7%) and without (45%) surgical indications. Cardiac surgery was performed in 83% of transferred patients. In-hospital (14% vs 23%) and 1-year (20% vs 35%) mortality rates were significantly lower in transferred patients (P < .001). Among the patients not undergoing cardiac surgery despite an indication, 55 (54%) died within 1 year. The multivariate analysis identified the following independent predictive factors for in-hospital mortality: Staphylococcus aureus infective endocarditis (odds ratio: 1.93 [1.08, 3.47]), heart failure (odds ratio: 3.87 [2.28, 6.57]), central nervous system embolism (odds ratio: 2.95 [1.41, 5.14]), and Charlson score (odds ratio: 1.19 [1.09, 1.30]), whereas community acquisition (odds ratio: 0.52 [0.29, 0.93]), cardiac surgery (odds ratio: 0.42 [0.20, 0.87]), but not transfer (odds ratio: 1.23 [0.84, 3.95]) were identified as protective factors. One-year mortality was associated with S. aureus infective endocarditis (odds ratio: 1.82 [1.04, 3.18]), heart failure (odds ratio: 3.74 [2.27, 6.16]), and Charlson score (odds ratio: 1.23 [1.13, 1.33]), whereas cardiac surgery (odds ratio: 0.41 [0.21, 0.79]) was identified as a protective factor.

CONCLUSION

Patients not transferred to a referral cardiac surgery center have a worse prognosis compared to those ultimately transferred, as cardiac surgery is associated with lower mortality rates.

Morganella morganii, an Emerging Cause of Bloodstream Infections

Although recent reports of extensively antibiotic-resistant strains have highlighted the importance of Morganella morganii as an emerging pathogen, the epidemiology of serious infections due to this organism is not well defined. The objective of this study was to determine the incidence, determinants, and outcomes of Morganella morganii bloodstream infections (BSIs). Retrospective, population-based surveillance for Morganella morganii BSIs was conducted in Queensland, Australia, in 2000 to 2019; 709 cases were identified, for an annual incidence of 9.2 cases per million population. Most cases were of community onset, with 280 (39.5%) community-associated cases and 226 (31.9%) health care-associated cases. Morganella morganii BSIs were rare in children and young adults, and the incidence increased markedly with advancing age. The most common foci of infection were skin and soft tissue (131 cases [18.5%]), genitourinary (97 cases [13.7%]), and intraabdominal (90 cases [12.7%]). Most patients (580 cases [81.8%]) had at least one comorbid medical illness, with diabetes mellitus (250 cases [35.3%]), renal disease (208 cases [29.3%]), and congestive heart failure (167 cases [23.6%]) being most prevalent. Resistance to one or more of quinolones, co-trimoxazole, aminoglycosides, or carbapenems was observed in 67 cases (9.5%), and this did not change significantly over the study. The 30-day all-cause case fatality rate was 21.2%, and increasing age, nonfocal infection, heart failure, dementia, and cancer were independently associated with increased risk of death. Morganella morganii BSIs are increasing in our population, and elderly male subjects and individuals with comorbidities are at highest risk. Although antibiotic resistance is not a major contributor to the current burden in Queensland, ongoing surveillance is warranted. IMPORTANCE Recent reports of extensively antibiotic-resistant strains have highlighted the importance of Morganella morganii as an emerging pathogen. Despite its present and evolving importance as an agent of human disease, there is a limited body of literature detailing the epidemiology of serious infections due to Morganella morganii. Therefore, the objectives of this study were to examine the incidence and determinants of Morganella morganii BSIs and to examine risk factors for death in a large Australian population in 2000 to 2019.

Incidence of Monomicrobial Staphylococcus aureus Bacteremia: A Population-Based Study in Olmsted County, Minnesota – 2006 to 2020

Background

Population-based studies of Staphylococcus aureus bacteremia (SAB) in the United States are limited. We provide a contemporary evaluation of SAB incidence in Olmsted County, Minnesota, from 2006 to 2020.

Methods

This was a retrospective population-based study of all adult patients with SAB residing in Olmsted County from 1 January 2006 through 31 December 2020. Initial episodes of SAB were identified using the microbiology laboratory databases at both Olmsted Medical Center and Mayo Clinic Rochester.

Results

Overall, 541 incident SAB cases were identified with a median age of 66.8 (interquartile range, 54.4–78.5) years, and 60.4% were male. Among these cases, 298 (56.2%) were due to methicillin-susceptible S aureus (MSSA) and 232 (43.8%) cases of methicillin-resistant S aureus (MRSA). The overall age- and sex-adjusted SAB incidence rate (IR) was 33.9 (95% confidence interval [CI], 31.0–36.8) cases/100 000 person-years (PY). Males had a higher age-adjusted IR of 46.0 (95% CI, 41.0–51.0) cases/100 000 PY compared to females (IR, 24.4 [95% CI, 21.1–27.7] cases/100 000 PY). Age- and sex-adjusted SAB IRs due to MSSA and MRSA were 18.7 and 14.6 cases/100 000 PY, respectively, and the percentage of incident SAB cases due to MRSA fluctuated across the study period. There was no apparent temporal trend in SAB incidence over the study period (P = .093).

Conclusions

Our investigation represents the only contemporary population-based study in the United States. Despite the impression that SAB incidence may have increased based on Centers for Disease Control and Prevention surveillance data, our finding of no change in SAB incidence was somewhat unanticipated.

Excess Burden of Critical Illness Related to Inflammatory Bowel Disease

BACKGROUND

Although inflammatory bowel disease (IBD) is associated with major morbidity and mortality, few studies have evaluated its associated burden of critical illness.

AIMS

We sought to examine the epidemiology and outcome of ICU admission among patients with IBD in north Brisbane, Australia.

METHODS

A population-based cohort design was utilized. All admissions to ICUs serving the Metro North Hospital and Health Service among adult residents during 2017-2019 were included. Data were obtained from ICU clinical information systems with linkages to statewide admissions and death registries.

RESULTS

Among 9,011 ICU admissions, 101 (1.1%) were among patients with IBD of which 57 (0.6%) and 44 (0.5%) had UC and CD, respectively. The incidence of ICU admission was 379, 1,336, 1,514, and 1,429 per 100,000 annually among those without IBD, CD, UC and IBD, respectively. Patients with IBD were at excess risk for admission across all age groups with women at highest risk under age 50 and men thereafter. The all cause 90-day case-fatality rates following ICU admission were not significantly different among patient groups and were 18%, 12%, 15%, and 12% for CD, UC, IBD, and non-IBD, respectively. However, as compared to non-IBD patients, those with CD (151.8 vs. 39.4 per 100,000; RR 3.85; 95% CI, 1.25-9.02; p=0.013); UC (159.4 vs 39.4 per 100,000; RR 4.05; 95% CI, 1.48-8.84; p=0.005), and IBD 155.6 vs 39.4 per 100,000; RR 3.95; 95% CI, 1.96-7.10; p=0.002) were at significantly higher risk for mortality.

CONCLUSIONS

Patients with IBD suffer a major burden of critical illness. This article is protected by copyright. All rights reserved.

Endocarditis at a large community hospital with on-site cardiac surgery

Objective

Infective endocarditis (IE) is still a serious disease. The currently published EURO-ENDO registry showed a rate of surgery of 51.2% and a lower mortality in operated IE patients. We hypothesized differences between our data and the registry.

Methods

Retrospective single centre registry on the hospital course of patients with IE.

Results

In four years, 171 IE patients were treated at our hospital. Mean age of patients was 66.5 ± 13.8 years and 62.6% of patients were transferred from other hospitals. There were 85 (49.7%) patients with native valve IE (NVE), 53 (31%) with prosthetic valve IE (PVE) and 33 (19.3%) with either intra-cardiac device related IE (n = 29) or IE associated with central access lines (n = 4) (DRE). A total of 81.3% (n = 139) of patients were sent to cardiac surgery. Using a logistic regression model to analyse predictors of conservative instead of surgical therapy the only independent variables were: presence of large vegetation or abscesses (OR: 0.36, 95%CI 0.15-0.83; p = 0.016) and age (for each ten years) (OR: 1.61, 95%CI 1.11-2.32, p = 0.01). Hospital mortality was 21.6% (n = 37/171), with no difference (p = 0.97) between those who were operated (21.6%, n = 30/139) and those treated conservatively (21.9%, n = 7/32). Comparing those treated conservatively without an indication for surgery with those with an indication, mortality was 9.5% versus 45.5%, p = 0.02.

Conclusions

In this registry from a hospital with on-site cardiac surgery more than half of patients were referred. The rate of patients treated surgically was 81.3%. Hospital mortality was 21.6%, with no difference between operated and conservatively treated patients.

Data on prognostic factors associated with 3-month and 1-year mortality from infective endocarditis

This article describes supplementary tables and figures associated with the research paper entitled “Impact of referral bias on prognostic studies outcomes: insights from a population-based cohort study on infective endocarditis”. The aforementioned paper is a secondary analysis of data from the EI 2008 cohort on infective endocarditis and aimed at characterising referral bias. A total of 497 patients diagnosed with definite infective endocarditis between January 1^st and December 31^st 2008 were included in EI 2008. Data were collected from hospital medical records by trained clinical research assistants. Patients were divided into three groups: admitted to a tertiary hospital (group T), admitted to a non-tertiary hospital and referred secondarily to a tertiary hospital (group NTT) or admitted to a non-tertiary hospital and not referred (group NT). The pooled (NTT+T) group mimicked studies recruiting patients in tertiary hospitals only. Two different starting points were considered for follow up: date of first hospital admission and date of first admission to a tertiary hospital if any (hereinafter referred to as “referral time”). Referral bias is a type of selection bias which can occur due to recruitment of patients in tertiary hospitals only (excluding those who are admitted to non-tertiary hospitals and not referred to tertiary hospitals). This bias may impact the description of patients’ characteristics, survival estimates as well as prognostic factors identification. The six tables presented in this paper illustrate how patients’ selection (population-based sample [pooled (NT+NTT+T) group] versus recruitment in tertiary hospitals only [pooled (NTT+T) group]) might impact Hazards Ratios values for prognostic factors. Crude and adjusted Cox regression analyses were first performed to identify prognostic factors associated with 3-month and 1-year mortality in the whole sample using inclusion as the starting point. Analyses were then performed in the pooled (NTT+T) group first using inclusion as the starting point and finally using referral time as the starting point. Figures 1 to 3 illustrate how HR increase with time for covariates that were considered as time-varying covariates (covariate*time interaction).

Impact of referral bias on prognostic studies outcomes: insights from a population-based cohort study on infective endocarditis

PURPOSE

Prognostic studies derived from samples of patients managed in tertiary hospitals are subject to referral bias. We aimed to characterize this bias using the example of infective endocarditis.

METHODS

We analyzed data from a French population-based cohort, which included 497 patients with infective endocarditis. Patients were admitted directly to a tertiary hospital (Group T), admitted to a non-tertiary hospital and referred to a tertiary hospital (Group NTT) or not (Group NT). We compared patients' characteristics, survival rates and prognostic factors between groups.

RESULTS

Compared with Group T (n = 291), NTT patients (n = 144) were more often males (81.3% vs. 72.5%; P = .046), injection drug users (9.7% vs. 4.5%; P = .033), and had more frequent surgical indications (78.5% vs. 64.3%; P = .003). Compared with Group NT (n = 62), NTT patients were more often males (81.3% vs. 67.7%; P = .034) and had surgical indications more often (78.5% vs. 19.4%; P < .001). One-year survival was higher in NTT + T patients than in NT patients (73.0% vs. 56.1%; P = .01). Prognostic factors and hazard ratios estimates varied across groups.

CONCLUSIONS

When derived from samples mixing patients admitted directly and those referred to tertiary hospitals, validity of characteristics description, survival estimates, and hazard ratios is threatened by referral bias.

Does Referral Bias Impact Outcomes of Surgery for Degenerative Mitral Valve Disease?

BACKGROUND

Geographic origin is cited as a possible factor influencing outcomes of operation for repair or replacement of degenerative mitral valve (MV) disease. Our study aimed to identify the potential impact of referral bias on clinical outcomes of MV surgery.

METHODS

We analyzed clinical and echocardiographic information of 2353 patients undergoing primary or secondary MV surgery for degenerative MV disease. Patients were grouped as local (in-state), regional (5 surrounding states), or national referrals.

RESULTS

The number of patients (local, 827; regional, 809; national, 717) and median follow-up time (9.1 years) were similar between geographic groups. More comorbidities were found in the local patient group. Overall operative risk was 0.7% and was greater in local and regional patients compared with national patients (0.7% and 1.1% vs 0.1%, P = .05). Valve repair was performed in 97% of isolated MV surgeries, and repair rate was similar in the 3 geographic groups. The 3 groups had similar incidences of major morbidity, but local and regional groups had higher 30-day readmissions. In univariate analysis, survival was improved in national and regional patients compared with local patients; however in multivariable analysis this difference was no longer significant.

CONCLUSIONS

There were important variations in baseline demographic and clinical characteristics between referral groups; local and regional patients presented with more comorbid conditions compared with national referrals. Aside from a small difference in perioperative mortality, early outcomes were generally similar. Late survival, however, was superior in national patients, and this referral bias is explained by fewer associated medical illnesses.

Elderly versus non-elderly patients undergoing surgery for left-sided native valve infective endocarditis: A 10-year institutional experience

This retrospective study aimed to clarify the short- and mid-term outcomes of elderly patients who underwent surgery to treat left-sided native valve infective endocarditis (LSNIE). Between July 2005 and September 2015, 179 patients underwent surgical treatment for active LSNIE at a single institution. Patients were classified into two groups: ≥65 years (elderly group) and <65 years (non-elderly group). Clinical features, surgical information, postoperative complications, and three-year survival rates were compared. The average ages were 74.2 ± 6.4 and 45.2 ± 12.6 years in the elderly and non-elderly groups, respectively. The elderly group had a higher predicted mortality rate and a lower incidence of preoperative septic emboli-related complications. Echocardiographic assessments of infected valves were generally homogenous between the groups. The elderly patients had a higher in-hospital mortality rate than the non-elderly patients (26.3% vs. 5.7%, P = 0.001). For patients who survived to discharge, the three-year cumulative survival rates were 75.0% ± 8.2% and 81.2% ± 3.4% in the elderly and non-elderly groups, respectively (P = 0.484). In conclusion, elderly patients are at a higher risk of in-hospital mortality after surgery for LSNIE. However, once elderly patients are stabilized by surgical treatment and survive to discharge, the mid-term outcomes are promising.

Ischemia and No Obstructive Coronary Artery Disease: Prevalence and Correlates of Coronary Vasomotion Disorders

BACKGROUND

Determine the prevalence and correlates of microvascular and vasospastic angina in patients with symptoms and signs of ischemia but no obstructive coronary artery disease (INOCA).

METHODS

Three hundred ninety-one patients with angina were enrolled at 2 regional centers over 12 months from November 2016 (NCT03193294). INOCA subjects (n=185; 47%) had more limiting dyspnea (New York Heart Association classification III/IV 54% versus 37%; odds ratio [OR], 2.0 [1.3-3.0]; P=0.001) and were more likely to be female (68% INOCA versus 38% in coronary artery disease; OR, 1.9 [1.5 to 2.5]; P<0.001) but with lower cardiovascular risk scores (ASSIGN score median 20% versus 24%; P=0.003). INOCA subjects had similar burden of angina (Seattle Angina Questionnaire) but reduced quality of life compared with coronary artery disease; subjects (EQ5D-5 L index 0.60 versus 0.65 units; P=0.041).

RESULTS

An interventional diagnostic procedure with reference invasive tests including coronary flow reserve, microvascular resistance, and vasomotor responses to intracoronary acetylcholine (vasospasm provocation) was performed in 151 INOCA subjects. Overall, 78 (52%) had isolated microvascular angina, 25 (17%) had isolated vasospastic angina, 31 (20%) had both, and 17 (11%) had noncardiac chest pain. Regression analysis showed inducible ischemia on treadmill testing (OR, 7.5 [95% CI, 1.7-33.0]; P=0.008) and typical angina (OR, 2.7 [1.1-6.6]; P=0.032) were independently associated with microvascular angina. Female sex tended to associate with a diagnosis of microvascular angina although this was not significant (OR, 2.7 [0.9-7.9]; P=0.063). Vasospastic angina was associated with smoking (OR, 9.5 [2.8-32.7]; P<0.001) and age (OR, 1.1 per year, [1.0-1.2]; P=0.032].

CONCLUSIONS

Over three quarters of patients with INOCA have identifiable disorders of coronary vasomotion including microvascular and vasospastic angina. These patients have comparable angina burden but reduced quality of life compared to patients with obstructive coronary artery disease. Microvascular angina and vasospastic angina are distinct disorders that may coexist but differ in associated clinical characteristics, symptoms, and angina severity.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT03193294.

Are we missing the Staphylococcus aureus bacteraemia forest for the MRSA trees?

In this edition of the journal, Jokinen et al. report on a population based study of Staphylococcus aureus bacteraemia (SAB) in Finland. They observe increasing incidence of cases over time that are associated with an increase in blood culture sampling. As compared to methicillin-sensitive SAB that increases during the study period, the incidence of methicillin-resistant SAB increases and then decreases. The proportion of cases with penicillin-sensitive SAB markedly increases in the study representing 43% of isolates in the most recent year of surveillance. While much attention and focus is typically placed on methicillin-resistant SAB, the major part of the burden of illness associated with SAB is from methicillin-sensitive and penicillin-sensitive strains. A narrow focus on prevention of methicillin-resistant Staphylococcus aureus will only have a limited impact on the overall burden of disease due to SAB.

Staphylococcus aureus bacteraemia and endocarditis - epidemiology and outcome: a review

PURPOSE

To review the epidemiology of Staphylococcus aureus bacteraemia (SAB) and endocarditis (SAE), and discuss the short- and long-term outcome.  Materials and methods: A literature review of the epidemiology of SAB and SAE.

RESULTS

The reported incidence of SAB in Western countries is 16-41/100,000 person-years. Increasing incidence has been observed in many regions, in Iceland by 27% during 1995-2008. The increase is believed to depend on changes in population risk factors and possibly better and more frequent utilization of diagnostic procedures. S. aureus is now the leading causes of infective endocarditis (IE) in many regions of the world. It accounts for 15-40% of all IE cases, and the majority of cases in people who inject drugs (PWID). Recently, the incidence of SAE in PWID in Stockholm, Sweden, was found to be 2.5/1000 person-years, with an in-hospital mortality of 2.5% in PWID as compared to 15% in non-drug users. The 30-day mortality associated with SAB amounts to 15-25% among adults in Western countries, but is lower in children (0-9%). Mortality associated with SAE is high (generally 20-30% in-hospital mortality), and symptomatic cerebral embolizations are common (12-35%). The 1-year mortality reported after SAB and SAE is 19-62% and reflects deaths from underlying diseases and complications caused by the infection. In a subset of SAE cases, valvular heart surgery is needed (15-45%), but active intravenous drug use seems to be a reason to refrain from surgery. Despite its importance, there are insufficient data on the optimal management of SAB and SAE, especially on the required duration of antibiotic therapy.  Conclusions: The epidemiology of SAB and SAE has been changing in the past decades. They still carry a substantial morbidity and mortality. Intensified studies on treatment are warranted for improving patient outcome.

Epidemiology of Live Born Infants with Nonimmune Hydrops Fetalis-Insights from a Population-Based Dataset

OBJECTIVE

To evaluate the incidence, etiology, and 1-year mortality of nonimmune hydrops fetalis (NIHF) and to identify risk factors for mortality in a contemporary population-based dataset.

STUDY DESIGN

The California Office of Statewide Health Planning and Development maintains a database linking maternal and infant hospital discharge, readmissions, and birth and death certificate date from 1 year before to 1 year after birth. We searched the database (2005-2012) for infants with NIHF (identified by the International Classification of Diseases, 9th Revision, Clinical Modification code). Hazard models were used to identify risk factors for mortality in infants with NIHF; results are presented as hazard ratios (HRs, 95% CI).

RESULTS

The incidence of NIHF was 2.5 out of 10 000 among live born infants. Neonatal mortality was 35.1% (364 out of 1037) and overall mortality was 43.2% (448 out of 1037) at 1 year of age. Gestational age (GA) was predictive of mortality with a HR of 2.4 (95% CI 1.9-3.2) for preterm compared with term infants. The GA-adjusted HR for mortality was 1.3 (95% CI 1.1-1.6) for polyhydramnios and 1.5 (95% CI 1.2-2.0) for large for gestational age infants compared with appropriate for GA infants. Aneuploid infants with critical congenital heart disease had an adjusted HR of 2.3 (95% CI 1.5-3.6) compared with euploid infants without a structural birth defect.

CONCLUSIONS

In this large, population-based study, prematurity, polyhydramnios, and large for gestational age were predictors of increased mortality. Mortality is highly variable among euploid and aneuploid infants with and without structural birth defects and critical congenital heart disease.

Temporal Trends in the Prevalence of Infective Endocarditis in Germany Between 2005 and 2014

Infective endocarditis (IE) is a potentially life-threatening disease. Little is known about temporal trends in its prevalence in Germany. In 2009, recommendations for antibiotic prophylaxis were deescalated in the revised European Society of Cardiology guideline to include only patients at high risk of IE. We selected patients with the discharge diagnosis of IE based on the International Classification of Diseases code I33 in the nationwide database of the Federal Statistical Office of Germany. We identified 94,364 patients with a diagnosis of IE from January 2005 to December 2014. Mean prevalence was 11.6 per 100,000 citizens per year in this 10-year-period. The annual IE prevalence showed a continuous small increase from 2006 to 2010 (9.5 to 10.6 IE diagnoses per 100,000 citizens) and a larger increase from 2011 to 2014 (11.1 to 14.4 IE diagnoses per 100,000 citizens; linear regression: β 2.9, 95% confidence interval 1.1 to 4.6; p = 0.006). The prevalence of IE in Germany was lower compared to the United States but higher compared to England. Overall, 15,995 patients (17%) died in hospital. Case fatality rate after a diagnosis of IE remained largely constant from 2005 to 2014. In conclusion, the annual prevalence of IE continuously increased during the observed period with more pronounced trend after the revised 2009 European Society of Cardiology guideline.

Burden of community-onset bloodstream infections, Western Interior, British Columbia, Canada

Although community-onset bloodstream infection (BSI) is recognized as a major cause of morbidity and mortality, its epidemiology has not been well defined in non-selected populations. We conducted population-based surveillance in the Interior Health West region of British Columbia, Canada in order to determine the burden associated with community-onset BSI. A total of 1088 episodes were identified for an overall annual incidence of 117·8/100 000 of which 639 (58·7%) were healthcare-associated (HA) and 449 (41·3%) were community-associated (CA) BSIs for incidences of 69·2 and 48·6/100 000, respectively. The incidence of community-onset BSI varied by age and gender and elderly males were at the highest risk. Overall 964 (88·6%) episodes resulted in hospital admission for a median length of stay of 8 days; the total days of acute hospitalization associated with community-onset BSI was 13 530 days or 1465 days/100 000 population per year. The in-hospital mortality rate was 10·6% (102/964) and this was higher for HA-BSI (72/569, 12·7%) compared to CA-BSI (30/395, 7·6%, P = 0·014) episodes. Community-onset BSI, especially HA-BSI, is associated with a major burden of illness.

Temporal trends in infective endocarditis epidemiology from 2007 to 2013 in Olmsted County, MN

BACKGROUND

The aim of this study is to determine if there have been contemporary shifts in infective endocarditis (IE) epidemiology in our local population; an analysis of cases from 2007 to 2013 was conducted.

METHODS

This is a population-based review of all adults (≥18 years) residing in Olmsted County, MN, with definite or possible IE using the Rochester Epidemiology Project from January 1, 2007, to December 31, 2013.

RESULTS

We identified 51 cases of IE in Olmsted County, MN, between 2007 and 2013. Median age of IE cases was 68.8 years (interquartile range 55.6-76.5), and 41% were females. Age- and sex-adjusted incidence of IE was 7.4 (95% CI 5.3-9.4) cases per 100,000 person-years. From a multivariable Poisson regression model, incidence of IE did not change significantly during the study period (P = .222) but was significantly higher in males and those of older age (P < .001). The annual incidences (per 100,000 person-years) were 2.5 for Staphylococcus aureus, 1.1 for viridans group streptococci, 1.6 for Enterococcus species, and 0.8 for coagulase-negative staphylococci. Only 19.6% (10/51) of Olmsted County patients underwent valve surgery between 2007 and 2013 as compared with 44.4% (197/444) of non-Olmsted County patients treated at Mayo Clinic Rochester.

CONCLUSION

In this population-based study, no significant change in the overall incidence of IE in Olmsted County, MN, between 2007 and 2013 was seen, and it was similar to that seen between 1970 and 2006. Male gender and older age were associated with increased IE risk. With a lesser extent of cases attributable to viridans group streptococcal IE compared with previous years, S aureus was the predominant pathogen in IE cases during 2007 to 2013. The relatively low valve surgery rate was disparate from that reported from large, tertiary care centers (including our own) with non-population-based cohorts, which are subject to referral bias and can influence the expected characterization of IE.

Back pain, leg swelling and a cardiac arrest: an interesting case of endocarditis

A 66-year-old woman with a history of tissue aortic valve replacement and chronic back pain presented to the emergency department with a suspected right leg deep vein thrombosis. A recent outpatient MRI had revealed discitis. A ventricular fibrillation cardiac arrest occurred in the emergency department. Cardiac output was restored on the fifth defibrillation. A transthoracic echocardiogram showed large aortic valve vegetations. Clinical impression was of infective endocarditis with cardiac arrest secondary to coronary artery embolisation. Peripheral blood cultures grew Cardiobacterium hominis, and appropriate intravenous antibiotic therapy was administered. The infected prosthetic valve was excised. The patient experienced postoperative complete heart block and a right hemisphere cerebrovascular accident, however she is now recovering well. This case describes an unusual case of infective endocarditis secondary to C. hominis, with disc, leg, coronary artery and brain septic embolisation. Infective endocarditis is an important differential diagnosis in multisystem presentations.

External validation of bloodstream infection mortality risk score in a population-based cohort

A risk score was recently derived to predict mortality in adult patients with Gram-negative bloodstream infection (BSI). The aim of this study was to provide external validation of the BSI mortality risk score (BSIMRS) in a population-based cohort. All residents of Olmsted County, Minnesota, with Escherichia coli and Pseudomonas aeruginosa BSI from 1 January 1998 to 31 December 2007 were identified. Logistic regression was used to examine the association between BSIMRS and mortality. Area under receiver operating characteristic curve (AUC) was calculated to quantify the discriminative ability of the BSIMRS to predict a variety of short-term and long-term outcomes. Overall, 424 unique Olmsted County residents with first episodes of E. coli and P. aeruginosa BSI were included in the study. Median age was 68 (range 0-99) years, 280 (66%) were women, 61 (14%) had cancer and 9 (2%) had liver cirrhosis. The BSIMRS was associated with 28-day mortality (p <0.001) with an AUC of 0.86. There was an almost 56% increase in 28-day mortality for each point increase in BSIMRS (OR 1.56, 95% CI 1.40-1.78). A BSIMRS ≥ 5 had a sensitivity of 74% and a specificity of 87% to predict 28-day mortality with a negative predictive value of 97%. The BSIMRS had AUC of 0.85, 0.85 and 0.81 for 7-, 14- and 365-day mortality, respectively. BSIMRS stratified mortality with high discrimination in a population-based cohort that included patients of all age groups who had a relatively low prevalence of cancer and liver cirrhosis.

Characteristics of invasive Staphylococcus aureus infections in three regions of Korea, 2009-2011: a multi-center cohort study

BACKGROUND

Despite the importance of invasive Staphylococcus aureus (ISA) infection, its overall burden in non-selected populations has only been defined in a small number of studies in Europe and North America. To define the characteristics of ISA infections in Korea, we conducted a multi-center cohort study to estimate population-based incidence rates.

METHODS

We conducted a multicenter prospective cohort study at nine university-affiliated active-surveillance core centers (ASCs) in three regions of Korea. To cover all available clinical microbiologic laboratories, we classified the laboratories in these regions into three groups according to their clinical environment as: 1) Nine ASCs, 2) Five major commercial laboratories and 3) Forty-four acute-care hospital-affiliated microbiology laboratories. We requested all the laboratories to report prospectively their numbers of cases of S. aureus isolated from normally sterile sites. Detailed clinical information was collected about the cases in the nine ASCs.

RESULTS

From 1 July 2009 to 30 June 2011, a total of 1,198 cases of ISA infection were identified at the nine ASCs, including 748 (62%) methicillin-resistant S. aureus (MRSA) infections. Most (81%) ISA infections were healthcare-associated (HCA): 653 (55%) hospital-onset and 322 (27%) community-onset. 223 (19%) were community-associated infections. The most common primary diagnosis was catheter-associated infection (225 cases, 19%). Respiratory tract infection (160, 13%), skin & soft tissue (152, 13%) and bone & joint infections (120, 10%) were also common. 30-day and 12-week mortality rates were 25.6% (262/1,024) and 36.5% (314/860), respectively. Complications, including metastatic infection within 12 weeks, occurred in 17.8% of ISA infections. The most common site of metastatic infection was the lung (9.8%, 84/860). Based on the total of 2,806 observed cases of ISA infection, estimated annual rates of ISA and invasive MRSA infections were 43.3 and 27.7 per 100,000 populations, respectively.

CONCLUSIONS

Our data provide important information about the clinical characteristics of ISA infections. We estimate that over 21,000 ISA infections and 13,000 invasive MRSA infections occurred in Korea in 2010.

Infective endocarditis epidemiology over five decades: a systematic review

AIMS

To Assess changes in infective endocarditis (IE) epidemiology over the last 5 decades.

METHODS AND RESULTS

We searched the published literature using PubMed, MEDLINE, and EMBASE from inception until December 2011.

DATA FROM

Einstein Medical Center, Philadelphia, PA were also included. Criteria for inclusion in this systematic review included studies with reported IE microbiology, IE definition, description of population studied, and time frame. Two authors independently extracted data and assessed manuscript quality. One hundred sixty studies (27,083 patients) met inclusion criteria. Among hospital-based studies (n=142; 23,606 patients) staphylococcal IE percentage increased over time, with coagulase-negative staphylococcus (CNS) increasing over each of the last 5 decades (p<0.001) and Staphylococcus aureus (SA) in the last decade (21% to 30%; p<0.05). Streptococcus viridans (SV) and culture negative (CN) IE frequency decreased over time (p<0.001), while enterococcal IE increased in the last decade (p<0.01). Patient age and male predominance increased over time as well. In subgroup analysis, SA frequency increased in North America, but not the rest of the world. This was due, in part, to an increase in intravenous drug abuse IE in North America (p<0.001). Among population-based studies (n=18; 3,477 patients) no significant changes were found.

CONCLUSION

Important changes occurred in IE epidemiology over the last half-century, especially in the last decade. Staphylococcal and enterococcal IE percentage increased while SV and CN IE decreased. Moreover, mean age at diagnosis increased together with male:female ratio. These changes should be considered at the time of decision-making in treatment of and prophylaxis for IE.

High age predicts low referral of hyperthyroid patients to specialized hospital departments: evidence for referral bias

BACKGROUND

Hospital-based studies may be hampered by referral bias. We investigated how the phenomenon may influence studies of hyperthyroid patients.

METHODS

By means of a computer-based linkage to the laboratory database and subsequent detailed evaluation of subjects with abnormal test results, we prospectively identified all 1148 patients diagnosed with overt hyperthyroidism in a four-year period in and around Aalborg City, Denmark. Each patient was classified according to nosological type of hyperthyroidism. We studied the referral pattern of patients to local hospital units, and analyzed how referral depended on subtype of disease, sex, age, and degree of biochemical hyperthyroidism.

RESULTS

In a 4-year period, 1032 hyperthyroid patients were diagnosed at primary care offices, and 435 of these (42.2%) were referred to specialized units, 92 patients had hyperthyroidism diagnosed in other hospital departments (referral: 43, 46.7%), and 24 patients had hyperthyroidism diagnosed at the specialized unit after referral for other diseases. Patients suffering from Graves' disease (GD; n=474, median age=65.8 years) were referred more often (odds ratio=1.7 [95% confidence interval 1.3-2.2]) than those diagnosed with multinodular toxic goiter (MNTG; n=525, median age=74.6 years). Higher age was associated with less referral of patients suffering from MNTG (referred vs. nonreferred patients, 64.0 vs. 77.4 years, p<0.001) and GD (43.9 vs. 56.4 years, p<0.001), whereas GD patients referred to a hospital had more severe biochemical hyperthyroidism (serum total triiodothyronine, 4.86 vs. 3.79 nmol/L; serum total thyroxine, 204 vs. 180 nmol/L; both p<0.001). Findings were confirmed in multivariate models reporting age as a significant predictor for referral in both GD and MNTG patients (both p<0.001). Among referred hyperthyroid patients (all combined), those aged up to 40 years (referral rate, 66.8%) were represented 11.6 (6.6-20.6) times more often than those aged 80 years and above (referral rate, 14.8%).

CONCLUSIONS

Hyperthyroid patients referred to a specialized hospital unit were younger (GD+MNTG) and had more severe biochemical hyperthyroidism (GD) compared to nonreferred patients. Thus, referral bias may influence hospital-based studies of hyperthyroid patients, and may hamper external generalization of such studies. Whether the referral bias of hyperthyroid patients in Denmark can be generalized to other countries or cultures remains unknown.

Overall burden of bloodstream infection and nosocomial bloodstream infection in North America and Europe

In this systematic review, we estimated the total number of episodes of bloodstream infection (BSI) and deaths from BSI per year in North America and Europe, using data from population-based settings. Then, we estimated the number of episodes and deaths from nosocomial BSI from population-based studies and nosocomial infection surveillance systems. We estimated 575 000-677 000 episodes of BSI per year in North America (536 000-628 000 in the USA and 40 000-49 000 in Canada) and 79 000-94 000 deaths (72 000-85 000 in the USA and 7000-9000 in Canada), using estimates from three population-based studies. We estimated over 1 200 000 episodes of BSI and 157 000 deaths per year in Europe, using estimates from one population-based study in each of the following countries: Denmark (9100 episodes and 1900 deaths), Finland (8700 episodes and 1100 deaths) and England (96 000 episodes and 12 000-19 000 deaths). There were substantial differences in estimates of nosocomial BSI between population-based and nosocomial infection surveillance data. BSI has a major impact on the morbidity and mortality of the general population, as it ranks among the top seven causes of death in all included countries in North America and Europe. However, it is difficult to obtain precise estimates of nosocomial BSI, owing to the limited number of studies. This review highlights the need for a greater focus on BSI research in order to reduce the overall burden of disease by improving the outcome of patients with BSI. It also emphasizes the role of infection control and prevention methods in reducing the burden of nosocomial BSI.

Clinical significance of congestive heart failure in prosthetic valve endocarditis. A multicenter study with 257 patients

INTRODUCTION AND OBJECTIVES

There have been no studies conducted in the past that focus on the significance of congestive heart failure in patients with prosthetic valve endocarditis. We studied the incidence of congestive heart failure in patients with prosthetic valve endocarditis and analyzed its profile. In this study, we addressed the prognostic significance of heart failure in patients with prosthetic valve endocarditis and analyzed its outcome based on chosen therapeutic strategies.

METHODS

A total of 639 episodes of definite left-sided endocarditis were prospectively enrolled. Of them, 257 were prosthetic. Of the 257 episodes, 145 (56%) were diagnosed with heart failure. We compared the profiles of patients with prosthetic valve endocarditis based on the presence of heart failure, and performed a multivariate logistic regression model to establish the prognostic significance of heart failure in patients with prosthetic valve endocarditis and identified the prognostic factors of in-hospital mortality in these patients.

RESULTS

Persistent infection (odds ratio=3.6; 95% confidence interval, 1.9-6.9) and heart failure (odds ratio=3; 95% confidence interval, 1.5-5.8) are the strongest predictive factors of in-hospital mortality in patients with prosthetic valve endocarditis. The short-term determinants of prognosis in patients with prosthetic valve endocarditis and heart failure are persistent infection (odds ratio=2.8; 95% confidence interval, 1.2-6.5), aortic involvement (odds ratio=2.5; 95% confidence interval, 1.1-5.8), abscess (odds ratio=3.6; 95% confidence interval, 1.4-9.5), diabetes mellitus (odds ratio=2.9; 95% confidence interval, 1.1-7.7), and cardiac surgery (odds ratio=0.2; 95% confidence interval, 0.1-0.5).

CONCLUSIONS

The incidence of heart failure in patients with prosthetic valve endocarditis is very high. Heart failure increases the risk of in-hospital mortality by threefold in patients with prosthetic valve endocarditis. Persistent infection, aortic involvement, abscess, and diabetes mellitus are the independent risk factors associated with mortality in patients with prosthetic valve endocarditis and heart failure; however, cardiac surgery is shown to decrease mortality in these patients.

Defining the epidemiology of bloodstream infections: the 'gold standard' of population-based assessment

Bloodstream infections (BSIs) are a major cause of morbidity and mortality. Although population-based studies have been proposed as an optimal means to define their epidemiology, the merit of these designs has not been well documented. This report investigated the potential value of using population-based designs in defining the epidemiology of BSIs. Population-based BSI surveillance was conducted in Calgary, Canada (population 1.24 million) and illustrative comparisons were made between the overall and selected subgroup cohorts within five main themes. The value of population denominator data, and age and gender standardization for calculation and comparison of incidence rates were demonstrated. In addition, a number of biases including those related to differential admission rates, selected hospital admission, and referral bias were highlighted in non-population-based cohorts. Due to their comprehensive nature and intrinsic minimization of bias, population-based designs should be considered the gold standard means of defining the epidemiology of an infectious disease.

Incidence of antibiotic-resistant Escherichia coli bacteriuria according to age and location of onset: a population-based study from Olmsted County, Minnesota

OBJECTIVE

To better understand the epidemiology of drug-resistant Escherichia coli across health care and community settings.

PATIENTS AND METHODS

We conducted a population-based cohort study of the incidence of antibiotic-resistant E coli bacteriuria among different patient groups. All urine cultures with monomicrobial growth of E coli obtained from Olmsted County, Minnesota, residents from January 1, 2005, through December 31, 2009, were identified. The initial isolate per patient per year was included. Analyses were stratified by patient age and location of infection onset (ie, nosocomial, health care associated, and community associated).

RESULTS

We evaluated 5619 E coli isolates and the associated patients. During the study period, the incidence of drug-resistant bacteriuria did not change among children but increased significantly among adults of all ages, most markedly among elderly patients older than 80 years. In elderly patients, the incidence of bacteriuria with isolates resistant to fluoroquinolones increased from 464 to 1116 per 100,000 person-years (P<.001), and the incidence of bacteriuria with isolates resistant to fluoroquinolones plus trimethoprim-sulfamethoxazole increased from 274 to 512 per 100,000 person-years (P<.05). When analyzed by location of infection onset, incidence of bacteriuria with isolates resistant to trimethoprim-sulfamethoxazole, fluoroquinolones, trimethoprim-sulfamethoxazole plus fluoroquinolones, extended-spectrum cephalosporins, and more than 3 drug classes increased significantly among community-associated but not among nosocomial or health care-associated cases.

CONCLUSION

In this population-based study, the incidence of antibiotic-resistant E coli bacteriuria nearly doubled during the 5-year study period among elderly patients and those with community-associated isolates. These patient groups should be targets of interventions to slow the emergence and spread of antibiotic-resistant E coli.

Temporal trends in infective endocarditis in the context of prophylaxis guideline modifications: three successive population-based surveys

OBJECTIVES

The goal of this study was to evaluate temporal trends in infective endocarditis (IE) incidence and clinical characteristics after 2002 French IE prophylaxis guideline modifications.

BACKGROUND

There are limited data on changes in the epidemiology of IE since recent guidelines recommended restricting the indications of antibiotic prophylaxis of IE.

METHODS

Three 1-year population-based surveys were conducted in 1991, 1999, and 2008 in 3 French regions totaling 11 million inhabitants age ≥20 years. We prospectively collected IE cases from all medical centers and analyzed age- and sex-standardized IE annual incidence trends.

RESULTS

Overall, 993 expert-validated IE cases were analyzed (323 in 1991; 331 in 1999; and 339 in 2008). IE incidence remained stable over time (95% confidence intervals given in parentheses/brackets): 35 (31 to 39), 33 (30 to 37), and 32 (28 to 35) cases per million in 1991, 1999, and 2008, respectively. Oral streptococci IE incidence did not increase either in the whole patient population (8.1 [6.4 to 10.1], 6.3 [4.8 to 8.1], and 6.3 [4.9 to 8.0] in 1991, 1999, and 2008, respectively) or in patients with pre-existing native valve disease. The increased incidence of Staphylococcus aureus IE (5.2 [3.9 to 6.8], 6.8 [5.3 to 8.6], and 8.2 [6.6 to 10.2]) was not significant in the whole patient population (p = 0.228) but was significant in the subgroup of patients without previously known native valve disease (1.6 [0.9 to 2.7], 3.7 [2.6 to 5.1], and 4.1 [3.0 to 5.6]; p = 0.012).

CONCLUSIONS

Scaling down antibiotic prophylaxis indications was not associated with an increased incidence of oral streptococcal IE. A focus on avoidance of S. aureus bacteremia in all patients, including those with no previously known valve disease, will be required to improve IE prevention.

Bacillus cereus endocarditis in native aortic valve

Bacillus cereus endocarditis is rare. It has been implicated in immunocompromised individuals, especially in intravenous drug users as well as in those with a cardiac prosthesis. The patient was a 31-year-old ex-intravenous drug addict with a past history of staphylococcal pulmonary valve endocarditis, who presented with symptoms of decompensated cardiac failure. Echocardiography showed severe aortic regurgitation with an oscillating vegetation seen on the right coronary cusp of the aortic valve. The blood cultures grew Bacillus cereus. We report this as a rare case of Bacillus cereus endocarditis affecting a native aortic valve.

[Periaortic abscess and infective endocarditis: beware of this dangerous duo]

OBJECTIVE

To determine clinical, echocardiographic features, management and outcomes of patients presenting peri aortic abscess complicating infective endocarditis (IE) and demonstrate the impact of periaortic abscess on morbidity and mortality of these patients.

METHODS

We have analyzed clinical, microbiological, echocardiographic aspects, therapies and outcomes of patients with aortic abscess occurring during IE, and we compared these data with those of patients presenting IE without peri aortic abscess in the same period in the cardiology department of the University Hospital of Marrakech from January 2006 to January 2010.

RESULTS

Above 56 cases of infective endocarditis, 16 patients had an aortic abscess. Mean age was 33 ± 11 years with a clear male predominance in the group IE with abscess versus IE without abscess. Heart failure was noted in all patients in periaortic abscess group, and was more severe in this group compared to control. Streptococcus and staphylococcus predominated with no significant difference between the two groups. Transthoracic echocardiography coupled with transesophageal echocardiography made the diagnosis of aortic abscess witch was isolated in 11 cases and associated with other complications in five cases. In terms of complications, splenic infarction was more frequent in the group with abscess (25 versus 2.5%, P<0.05). There was not a significant difference between the two groups for the others complications. Surgery associated with a double antibiotic therapy was the standard treatment with a variable delay for surgery of four days to four weeks. Hospital mortality in the acute phase was higher in periaortic abscess group (37% versus 10%, P<0.05). The evolution of survivors at six months was favorable.

CONCLUSION

Periaortic abscess complicating IE is associated with a high morbidity and mortality in spite of modern approach as well as on medical or surgical treatment. It requires therefore a strict monitoring of patients with infective endocarditis.

Population-based laboratory assessment of the burden of community-onset bloodstream infection in Victoria, Canada

Although community-onset bloodstream infection (BSI) is recognized as a major cause of morbidity and mortality, its epidemiology has not been well defined in non-selected populations. We conducted population-based laboratory surveillance in the Victoria area, Canada during 1998-2005 in order to determine the burden associated with community-onset BSI. A total of 2785 episodes were identified for an overall annual incidence of 101·2/100,000. Males and the very young and the elderly were at highest risk. Overall 1980 (71%) episodes resulted in hospital admission for a median length of stay of 8 days; the total days of acute hospitalization associated with community-onset BSI was 28 442 days or 1034 days/100,000 population per year. The in-hospital case-fatality rate was 13%. Community-onset BSI is associated with a major burden of illness. These data support ongoing and future preventative and research efforts aimed at reducing the major impact of these infections.

[Infective endocarditis in the XXI century: epidemiological, therapeutic, and prognosis changes]

Infective endocarditis (IE) is an uncommon and severe disease. Nowadays, in developed countries, IE patients are older, usually have a degenerative heart valve disease, and up to 30% acquire this infection within the health care system. In consequence, staphylococci species are the most frequently isolated microorganisms. Antimicrobial treatment for IE has significantly changed over the last decades. In IE episodes due to Staphylococcus aureus, cloxacillin-resistance makes antimicrobial election more difficult. Other microorganisms, such as enterococci and some species of streptococci, show high rates of resistance to antimicrobial agents established in guidelines. Despite improvements in the diagnosis, and medical and surgical treatment of IE, this disease continues to be associated with high rates of in-hospital mortality. At present, due to epidemiological changes, antimicrobial prophylaxis can avoid few cases of IE. Prevention of nosocomial bacteremia, an early diagnosis of IE, prompt identification of IE patients at a higher risk of mortality, and a multidisciplinary approach of this disease could be valid strategies in order to improve the outcome of these patients.

Impact of healthcare-associated acquisition on community-onset Gram-negative bloodstream infection: a population-based study: healthcare-associated Gram-negative BSI

We performed a population-based study to examine the influence of healthcare-associated acquisition on pathogen distribution, antimicrobial resistance, short- and long-term mortality of community-onset Gram-negative bloodstream infections (BSI). We identified 733 unique patients with community-onset Gram-negative BSI (306 healthcare-associated and 427 community-acquired) among Olmsted County, Minnesota, residents from 1 January 1998 to 31 December 2007. Multivariate logistic regression was used to examine the association between healthcare-associated acquisition and microbiological etiology and antimicrobial resistance. Multivariate Cox proportional hazards regression was used to evaluate the influence of the site of acquisition on mortality. Healthcare-associated acquisition was predictive of Pseudomonas aeruginosa (odds ratio [OR] 3.14, 95% confidence intervals [CI]: 1.59-6.57) and the group of Enterobacter, Citrobacter, and Serratia species (OR 2.23, 95% CI: 1.21-4.21) as causative pathogens of community-onset Gram-negative BSI. Healthcare-associated acquisition was also predictive of fluoroquinolone resistance among community-onset Gram-negative bloodstream isolates (OR 2.27, 95% CI: 1.18-4.53). Healthcare-associated acquisition of BSI was independently associated with higher 28-day (hazard ratio [HR] 3.73, 95% CI: 2.13-6.93) and 1-year mortality (HR 3.60, 95% CI: 2.57-5.15). Because of differences in pathogen distribution, antimicrobial resistance, and outcomes between healthcare-associated and community-acquired Gram-negative BSI, identification of patients with healthcare-associated acquisition of BSI is essential to optimize empiric antimicrobial therapy.

Cardiobacterium hominis endocarditis: A case report and review of the literature

The present case report describes the clinical course of a patient who presented with Cardiobacterium hominis endocarditis. A review of the literature follows the case presentation. C hominis, a fastidious Gram-negative bacillus, is a member of the HACEK group of microorganisms (Haemophilus species, Actinobacillus actinomycetemcomitans, C hominis, Eikenella corrodens and Kingella kingae). Endocarditis caused by C hominis is uncommon and generally follows a subacute course. Patients may present with constitutional symptoms, symptoms related to valvular destruction or symptoms secondary to embolic events. Diagnosis requires identification of the pathogen from blood or vegetation by either culture or molecular techniques. Blood cultures may require prolonged incubation, highlighting the importance of incubating blood cultures for at least two to three weeks in patients with suspected endocarditis. In the past, C hominis was generally sensitive to penicillin. However, reports of beta-lactamase-producing C hominis have appeared in the literature over the past decade. The current recommendation for first-line treatment is a third-generation cephalosporin (ceftriaxone) for four weeks (six weeks if a prosthetic valve is in place).

Multiple-valve infective endocarditis: clinical, microbiologic, echocardiographic, and prognostic profile

Whether infection in more than 1 valve worsens the prognosis for endocarditis remains untested. We conducted the current study to determine the profile of multiple-valve endocarditis, compare multiple-valve endocarditis with single-valve endocarditis, and determine predictors of outcome. We conducted a prospective and observational study including 680 episodes of infective endocarditis consecutively diagnosed at 3 tertiary centers. Multiple valve involvement was present in 115 episodes (17%), and single valve involvement in 530 (78%). In the remaining 35 cases, valvular involvement could not be documented. Mean age of patients with multiple valve endocarditis was 58 years. Clinical complications were frequent (heart failure 65%, renal failure 44%, systemic embolisms 24%). The microorganism most frequently isolated was Staphylococcus aureus (22%).Factors predictive of in-hospital mortality in the univariate analysis were septic shock, prosthetic endocarditis, heart failure, and persistent infection. In the multivariate analysis, we detected heart failure (odds ratios [OR], 4.7; 95% confidence interval [CI], 1.6-13.8) and persistent infection (OR, 4.3; 95% CI, 1.7-10.8) as predictors of in-hospital mortality. Compared to single-valve endocarditis, multiple-valve disease was associated more frequently with heart failure (65% vs. 50%, p = 0.03), perivalvular complications (41% vs. 21%, p < 0.001), and heart surgery (70% vs. 54%, p = 0.002). Despite these differences, in-hospital mortality was similar (28% vs. 30%, p = 0.647). In conclusion, multiple-valve endocarditis has a poor clinical course. Mortality is similar to that of single-valve endocarditis, probably in relation with aggressive therapy including surgery in many patients. Heart failure and persistent infection are independent predictors of death.

Infective endocarditis in a child caused by Cardiobacterium hominis after right ventricular outflow tract reconstruction using an expanded tetrafluoroethylene conduit

Cardiobacterium hominis, a member of the HACEK group of organisms, is a rare cause of endocarditis. We report a case of infective endocarditis caused by C. hominis in a male child who had undergone right ventricular outflow tract (RVOT) reconstruction using an expanded polytetrafluoroethylene conduit for tetralogy of Fallot with pulmonary atresia. Two days before admission, the patient suffered from exertional shortness of breath. Right ventricular hypertension was confirmed and RVOT stenosis was suspected based on the echocardiography findings. A CT scan revealed vegetation above the cusp of the conduit. An emergency operation was performed to avoid a pulmonary embolism due to large friable vegetation. C. hominis was cultured from the blood and the vegetation, prompting a diagnosis of prosthetic valve endocarditis. The patient was discharged after a 6-week course of intravenous ceftriaxone therapy.

Temporal trends in Enterobacter species bloodstream infection: a population-based study from 1998-2007

Enterobacter species are the fourth most common cause of Gram-negative bloodstream infection (BSI). We examined temporal changes and seasonal variation in the incidence rate of Enterobacter spp. BSI, estimated 28-day and 1-year mortality, and determined in vitro antimicrobial resistance rates of Enterobacter spp. bloodstream isolates in Olmsted County, Minnesota, from 1 January 1998 to 31 December 2007. Multivariable Poisson regression was used to examine temporal changes and seasonal variation in incidence rate and Kaplan-Meier method was used to estimate 28-day and 1-year mortality. The median age of patients with Enterobacter spp. BSI was 58 years and 53% were female. The overall age- and gender-adjusted incidence rate of Enterobacter spp. BSI was 3.3 per 100,000 person-years (95% CI 2.3-4.4). There was a linear trend of increasing incidence rate from 0.8 (95% CI 0-1.9) to 6.2 (95% CI 3.0-9.3) per 100,000 person-years between 1998 and 2007 (p 0.002). There was no significant difference in the incidence rate of Enterobacter spp. BSI during the warmest 4 months compared to the remainder of the year (incidence rate ratio 1.06; 95% CI 0.47-2.01). The overall 28-day and 1-year mortality rates of Enterobacter spp. BSI were 21% (95% CI 8-34%) and 38% (95% CI 22-53%), respectively. Up to 13% of Enterobacter spp. bloodstream isolates were resistant to third-generation cephalosporins. To our knowledge, this is the first population-based study to describe the epidemiology and outcome of Enterobacter spp. BSI. The increase in incidence rate of Enterobacter spp. BSI over the past decade, coupled with its associated antimicrobial resistance, dictate the need for further investigation of this syndrome.

Influence of referral bias on the clinical characteristics of patients with Gram-negative bloodstream infection

Referral bias can influence the results of studies performed at tertiary-care centres. In this study, we evaluated demographic and microbiological factors that influenced referral of patients with Gram-negative bloodstream infection (BSI). We identified 2919 and 846 unique patients with Gram-negative BSI in a referral cohort of patients treated at Mayo Clinic Hospitals and a population-based cohort of Olmsted County, Minnesota, residents between 1 January 1998 and 31 December 2007, respectively. Multivariable logistic regression analysis was used to determine factors associated with referral. Elderly patients aged ≥80 years with Gram-negative BSI were less likely to be referred than younger patients [odds ratio (OR) 0·43, 95% confidence intervals (CI) 0·30-0·62] as were females (OR 0·63, 95% CI 0·53-0·74). After adjusting for age and gender, bloodstream isolates of Escherichia coli (OR 0·50, 95% CI 0·43-0·58) and Proteus mirabilis (OR 0·49, 95% CI 0·30-0·82) were underrepresented in the referral cohort; and Pseudomonas aeruginosa (OR 2·26, 95% CI 1·70-3·06), Enterobacter cloacae (OR 2·31, 95% CI 1·53-3·66), Serratia marcescens (OR 2·34, 95% CI 1·33-4·52) and Stenotrophomonas maltophilia (OR 17·94, 95% CI 3·98-314·43) were overrepresented in the referral cohort. We demonstrated that demographic and microbiological characteristics of patients with Gram-negative BSI had an influence on referral patterns. These factors should be considered when interpreting results of investigations performed at tertiary-care centres.

[Infectious endocarditis in a Norwegian hospital 1997-2006]

BACKGROUND

Infective endocarditis is a serious disease with high morbidity and mortality. The causative microorganism and predisposing factors have changed over time. Four retrospective studies of this condition have been published in Norway; the most recent in 1998. Aetiology, treatment and mortality have been reviewed for such patients admitted to a Norwegian hospital in a 10-year period.

MATERIAL AND METHODS

Medical records were reviewed for all patients ≥ 18 years admitted to Aalesund hospital, and diagnosed with infective endocarditis (as primary or secondary diagnosis) according to relevant ICD 9 and ICD 10 codes, in the period 01.01.1997-31.12.2006. Demographical, clinical, and laboratory data were recorded.

RESULTS

57 patients were diagnosed with infective endocarditis; the average age was 66 years and 37 were men. The average annual incidence was 6.3/100000 pr year. The average length of treatment was six weeks, and the first choice of antibiotics was usually a combination of penicillin and aminoglycosides (46%). The most common causative microorganism was S.aureus (21%). 42 (74%) patients had one or more complications. Nine (16%) patients died during their hospital stay.

INTERPRETATION

The incidence of infective endocarditis in Aalesund hospital was in the upper range of previous reports. In accordance with previous studies, we found that staphylococcus is currently the most common causative micro-organism. The age of onset has increased compared to earlier Norwegian studies.