Infective endocarditis in Western Norway: a 20-year retrospective survey.

BACKGROUND: To investigate epidemiological trends of infective endocarditis (IE) in western Norway a retrospective study was performed. METHODS: Characteristics of 706 IE admissions from 1996 to 2005 and 2006 to 2015 were analysed and compared using the Chi-square test for categorical variables and the t-test for age. Survival was analysed by multiple Cox regression and reported by the hazard ratio (HR). RESULTS: Mean annual incidence rates increased from 4.6 to 7.4 per 100,000 inhabitants (rate ratio: 1.97, 95% confidence interval: 1.52-2.56, p < .001). Non-viridans streptococci, enterococci and Staphylococcus aureus (S. aureus), were all independently associated with increased mortality. The frequency of IE caused by enterococci increased from 3.7 to 13.0% (p < .001). The proportion of intravenous drug users (IVDU) increased from 16.5 to 23.5% (p = .015) and had increasing aortic valve involvement (p = .023). Prosthetic valve endocarditis (PVE) constituted 30% of IE cases in both decades with biological PVE increasing from 9.4 to 22.1% (p < .001) and mechanical PVE decreasing from 18.7 to 8.9% (p < .001). In the last decade, valve replacement surgery was performed in 37.6% of the patients, of which 85.5% received a bioprosthesis. CONCLUSIONS: The incidence of IE increased significantly. Non-viridans streptococci, enterococci and S. aureus were all significantly associated with increased mortality. The increased number of enterococcal IE and the increased number of IVDUs with left-sided IE constituted new challenges. Biological implants were preferred in a majority of patients requiring surgery.

Immune responses after live attenuated influenza vaccination.

Since 2003 (US) and 2012 (Europe) the live attenuated influenza vaccine (LAIV) has been used as an alternative to the traditional inactivated influenza vaccines (IIV). The immune responses elicted by LAIV mimic natural infection and have been found to provide broader clinical protection in children compared to the IIVs. However, our knowledge of the detailed immunological mechanisims induced by LAIV remain to be fully elucidated, and despite 14 years on the global market, there exists no correlate of protection. Recently, matters are further complicated by differing efficacy data from the US and Europe which are not understood. Better understanding of the immune responses after LAIV may aid in achieving the ultimate goal of a future "universal influenza vaccine". In this review we aim to cover the current understanding of the immune responses induced after LAIV.

Influenza Virus Hemagglutinin Stalk-Specific Antibodies in Human Serum are a Surrogate Marker for In Vivo Protection in a Serum Transfer Mouse Challenge Model.

The immunogenicity of current influenza virus vaccines is assessed by measuring an increase of influenza virus-specific antibodies in a hemagglutination inhibition assay. This method exclusively measures antibodies against the hemagglutinin head domain. While this domain is immunodominant, it has been shown that hemagglutination inhibition titers do not always accurately predict protection from disease. In addition, several novel influenza virus vaccines that are currently under development do not target the hemagglutinin head domain, but rather more conserved sites, including the hemagglutinin stalk. Importantly, antibodies against the hemagglutinin stalk do not show activity in hemagglutination inhibition assays and will require different methods for quantification. In this study, we tested human serum samples from a seasonal influenza virus vaccination trial and an avian H5N1 virus vaccination trial for antibody activities in multiple types of assays, including binding assays and also functional assays. We then performed serum transfer experiments in mice which then received an H1N1 virus challenge to assess the in vivo protective effects of the antibodies. We found that hemagglutinin-specific antibody levels measured in an enzyme-linked immunosorbent assay (ELISA) correlated well with protection from weight loss in mice. In addition, we found that weight loss was also inversely correlated with the level of serum antibody-dependent cellular cytotoxicity (ADCC) as measured in a reporter assay. These findings indicate that protection is in part conferred by Fc-dependent mechanisms. In conclusion, ELISAs can be used to measure hemagglutinin-specific antibody levels that could serve as a surrogate marker of protection for universal influenza virus vaccines.IMPORTANCE Influenza viruses are a serious concern for public health and cause a large number of deaths worldwide every year. Current influenza virus vaccines can confer protection from disease, but they often show low efficacy due to the ever-changing nature of the viruses. Novel vaccination approaches target conserved epitopes of the virus, including the hemagglutinin stalk domain, to elicit universally protective antibodies that also bind to mutated viruses or new subtypes of viruses. Importantly, the hemagglutination inhibition assay-the only assay that has been accepted as a correlate of protection by regulatory authorities-cannot measure antibodies against the hemagglutinin stalk domain. Therefore, novel correlates of protection and assays to measure vaccine immunogenicity need to be developed. In this study, we correlated the results from multiple assays with protection in mice after transfer of human serum and a lethal virus challenge to investigate potential novel serological surrogate markers for protection.

Role of neutrophil to lymphocyte and monocyte to lymphocyte ratios in the diagnosis of bacterial infection in patients with fever.

PURPOSE: To study the role of the neutrophil:lymphocyte ratio (NLR) and monocyte:lymphocyte ratio (MLR) in discriminating between different patient groups hospitalized for fever due to infection and those without infection. METHODS: For 299 patients admitted to hospital for fever with unknown cause, a number of characteristics including NLR and MLR were recorded. These characteristics were used in a multiple multinomial regression analysis to estimate the probability of a final diagnostic group of bacterial, viral, clinically confirmed, or no infection. RESULTS: Both NLR and MLR significantly predicted final diagnostic group. Being highly correlated, however, both variables could not be retained in the same model. Both variables also interacted significantly with duration of fever. Generally, higher values of NLR and MLR indicated larger probabilities for bacterial infection and low probabilities for viral infection. Patients with septicemia had significantly higher NLR compared to patients with other bacterial infections with fever for less than one week. White blood cell counts, neutrophil counts, and C-reactive proteins did not differ significantly between septicemia and the other bacterial infection groups. CONCLUSIONS: NLR is a more useful diagnostic tool to identify patients with septicemia than other more commonly used diagnostic blood tests. NLR and MLR may be useful in the diagnosis of bacterial infection among patients hospitalized for fever.

Cardiac surgery for infective endocarditis in patients with intravenous drug use.

OBJECTIVES: Intravenous drug users have a high risk of infective endocarditis and reduced survival. Cardiac surgery may be recommended for these patients, but redo surgery is controversial. This study describes the characteristics and outcomes of intravenous drug users accepted for surgery during a 12-year period. METHODS: This retrospective study included 29 injecting drug users treated with valve surgery for endocarditis between January 2001 and December 2013 at a tertiary academic centre. Survival was assessed by Kaplan-Meier analysis. RESULTS: The median patient age was 36 (24-63) years and 27 patients (93%) were male. Staphylococcus aureus (52%) and Enterococcus faecalis (17%) were the most common microorganisms. Common illicit drugs were opioids (69%), amphetamines (52%) and benzodiazepines (24%). Mixed abuse was reported in 66% of patients. Seven patients (24%) had prior intracardial implants or native valve pathology. Twenty-five patients (86%) were positive for hepatitis C virus antibody, but none carried the human immunodeficiency virus. Twelve (41%) were homeless and 15 (52%) had poor dental hygiene. Three patients (10%) received medication-assisted rehabilitation before surgery. The main indications for surgery were regurgitation and secondary heart failure (86%), embolization (41%) and uncontrolled infection (24%). Aortic valve replacement was performed in 24 patients (83%), either as part of univalvular or multiple valve surgery. Seven patients (24%) had multivalvular endocarditis. All but 3 patients received biological valve prostheses. The 30-day mortality was 7% after first time surgery. During follow-up, 15 patients (52%) presented with reinfection: 10 (35%) were offered a second and 2 (7%) a third operation. Thirty-day mortality was 10% after redo surgery. Thirteen patients (45%) died within a median of 22 (0-84) months. Continued intravenous drug use was reported in 70 and 44% of patients after the first and second operation, respectively. CONCLUSIONS: Cardiac surgery for infective endocarditis has acceptable early postoperative results among intravenous drug users. The 2- and 5-year survival were 79 and 59%, respectively. The number of reinfections was high within 2 years, as continued drug use seems to be a major challenge for this group.

Bacterial and Hematological Findings in Infected Total Hip Arthroplasties in Norway Assessment of 278 Revisions Due to Infection in the Norwegian Arthroplasty Register.

Our aim was to assess the bacterial findings in infected total hip arthroplasties (THAs) in Norway. We also wanted to investigate the relationship between causal bacteria and hematological findings. Revisions reported to the Norwegian Arthroplasty Register (NAR) due to infection after total hip arthroplasty during the period 1993 through September 2007 were identified. One single observer visited ten representative hospitals where clinical history, preoperative blood samples and the bacterial findings of intraoperative samples were collected. Bacterial growth in two or more samples was found in 278 revisions, and thus included. The following bacteria were identified: Coagulase-negative staphylococci (CoNS) (41%), Staphylococcus aureus (S. aureus) (19%), streptococci (11%), polymicrobial infections (10%), enterococci (9%), Gram-negative bacteria (6%) and others (4%). CoNS were the most common bacteria throughout the period but in the acute postoperative infections (< 3 weeks) S. aureus was the most frequent bacterial finding. We found no change in the distribution of the bacterial groups over time. S. aureus appears correlated with a higher C-reactive protein value (CRP) (mean 140 (95% Confidence interval (CI): 101-180)) than CoNS (mean 42 (CI: 31-53)). S. aureus also correlated with a higher erythrocyte sedimentation rate value (ESR) (mean 67 (CI: 55-79)) than CoNS (mean 47 (CI: 39-54)).

Matrix M H5N1 Vaccine Induces Cross-H5 Clade Humoral Immune Responses in a Randomized Clinical Trial and Provides Protection from Highly Pathogenic Influenza Challenge in Ferrets.

BACKGROUND AND METHODS: Highly pathogenic avian influenza (HPAI) viruses constitute a pandemic threat and the development of effective vaccines is a global priority. Sixty adults were recruited into a randomized clinical trial and were intramuscularly immunized with two virosomal vaccine H5N1 (NIBRG-14) doses (21 days apart) of 30 µg HA alone or 1.5, 7.5 or 30 µg HA adjuvanted with Matrix M. The kinetics and longevity of the serological responses against NIBRG-14 were determined by haemagglutination inhibition (HI), single radial haemolysis (SRH), microneutralization (MN) and ELISA assays. The cross-H5 clade responses in sera were determined by HI and the antibody-secreting (ASC) cell ELISPOT assays. The protective efficacy of the vaccine against homologous HPAI challenge was evaluated in ferrets. RESULTS: The serological responses against the homologous and cross-reactive strains generally peaked one week after the second dose, and formulation with Matrix M augmented the responses. The NIBRG-14-specific seroprotection rates fell significantly by six months and were low against cross-reactive strains although the adjuvant appeared to prolong the longevity of the protective responses in some subjects. By 12 months post-vaccination, nearly all vaccinees had NIBRG-14-specific antibody titres below the protective thresholds. The Matrix M adjuvant was shown to greatly improve ASC and serum IgG responses following vaccination. In a HPAI ferret challenge model, the vaccine protected the animals from febrile responses, severe weight loss and local and systemic spread of the virus. CONCLUSION: Our findings show that the Matrix M-adjuvanted virosomal H5N1 vaccine is a promising pre-pandemic vaccine candidate. TRIAL REGISTRATION: ClinicalTrials.gov NCT00868218.

Increasing Resistance of Coagulase-Negative Staphylococci in Total Hip Arthroplasty Infections: 278 THA-Revisions due to Infection Reported to the Norwegian Arthroplasty Register from 1993 to 2007.

We investigated bacterial findings from intraoperative tissue samples taken during revision due to infection after total hip arthroplasty (THA). The aim was to investigate whether the susceptibility patterns changed during the period from 1993 through 2007. Reported revisions due to infection in the Norwegian Arthroplasty Register (NAR) were identified, and 10 representative hospitals in Norway were visited. All relevant information on patients reported to the NAR for a revision due to infection, including bacteriological findings, was collected from the medical records. A total of 278 revision surgeries with bacterial growth in more than 2 samples were identified and included. Differences between three 5-year time periods were tested by the chi-square test for linear trend. The most frequent isolates were coagulase-negative staphylococci (CoNS) (41%, 113/278) and Staphylococcus aureus (19%, 53/278). The proportion of CoNS resistant to the methicillin-group increased from 57% (16/28) in the first period, 1993-1997, to 84% (52/62) in the last period, 2003-2007 (P = 0.003). There was also significant increase in resistance for CoNS to cotrimoxazole, quinolones, clindamycin, and macrolides. All S. aureus isolates were sensitive to both the methicillin-group and the aminoglycosides. For the other bacteria identified no changes in susceptibility patterns were found.

Matrix M(TM) adjuvanted virosomal H5N1 vaccine induces balanced Th1/Th2 CD4(+) T cell responses in man.

T cellular responses play a significant role in mediating protective immune responses against influenza in humans. In the current study, we evaluated the ability of a candidate virosomal H5N1 vaccine adjuvanted with Matrix M(TM) to induce CD4(+) and CD8(+) T cell responses in a phase 1 clinical trial. We vaccinated 60 healthy adult volunteers (at days 0 and 21) with 30 µg haemagglutinin (HA) alone or 1.5, 7.5, or 30 µg HA formulated with Matrix M(TM). To evaluate the T cellular responses, lymphocytes were stimulated in vitro with homologous (A/Vietnam/1194/2004 [H5N1]) and heterologous H5N1 (A/Anhui/1/05 or A/Bar-headed Goose/Qinghai/1A/05) antigens. The antigen-specific cytokine responses were measured by intracellular cytokine staining and by multiplex (Luminex) assays. An increase in CD4(+) Th1 and Th2 cytokines was detected 21 days after the first vaccine dose. No increase in Th cytokine responses was observed after the second dose, although it is possible that the cytokine levels peaked earlier than sampling point at day 42. Formulation with the Matrix M(TM) adjuvant augmented both the homologous and cross-reactive cytokine response. Antigen-specific CD8(+) T cell responses were detected only in a few vaccinated individuals. The concentrations of Th1 and to a lesser extent, Th2 cytokines at 21 days post-vaccination correlated moderately with subsequent days 35 and 180 serological responses as measured by the microneutralisation, haemagglutination inhibition, and single radial hemolysis assays. Results presented here show that the virosomal H5N1 vaccine induced balanced Th1/Th2 cytokine responses and that Matrix M(TM) is a promising adjuvant for future development of candidate pandemic influenza vaccines.

Induction of broadly reactive anti-hemagglutinin stalk antibodies by an H5N1 vaccine in humans.

UNLABELLED: Influenza virus infections are a major public health concern and cause significant morbidity and mortality worldwide. Current vaccines are effective but strain specific due to their focus on the immunodominant globular head domain of the hemagglutinin (HA). It has been hypothesized that sequential exposure of humans to hemagglutinins with divergent globular head domains but conserved stalk domains could refocus the immune response to broadly neutralizing epitopes in the stalk. Humans have preexisting immunity against H1 (group 1 hemagglutinin), and vaccination with H5 HA (also group 1)--which has a divergent globular head domain but a similar stalk domain--represents one such sequential-exposure scenario. To test this hypothesis, we used novel reagents based on chimeric hemagglutinins to screen sera from an H5N1 clinical trial for induction of stalk-specific antibodies by quantitative enzyme-linked immunosorbent assay (ELISA) and neutralization assays. Importantly, we also investigated the biological activity of these antibodies in a passive transfer in a mouse challenge model. We found that the H5N1 vaccine induced high titers of stalk-reactive antibodies which were biologically active and protective in the passive-transfer experiment. The induced response showed exceptional breadth toward divergent group 1 hemagglutinins but did not extend to group 2 hemagglutinins. These data provide evidence for the hypothesis that sequential exposure to hemagglutinins with divergent globular head domains but conserved stalk domains can refocus the immune response toward the conserved stalk domain. Furthermore, the results support the concept of a chimeric hemagglutinin universal influenza virus vaccine strategy that is based on the same principle. IMPORTANCE: Influenza virus vaccines have to be reformulated and readministered on an annual basis. The development of a universal influenza virus vaccine could abolish the need for this cumbersome and costly process and would also enhance our pandemic preparedness. This study addressed the following questions, which are essential for the development of a hemagglutinin stalk-based universal influenza virus vaccine. (i) Can stalk-reactive antibodies be boosted by vaccination with divergent HAs that share conserved epitopes? (ii) How long-lived are these vaccine-induced stalk-reactive antibody responses? (iii) What is the breadth of this reactivity? (iv) Are these antibodies functional and protective? Our results further strengthen the concept of induction of stalk-reactive antibodies by sequential exposure to hemagglutinin immunogens with conserved stalk and divergent head domains. A universal influenza virus vaccine based on the same principles seems possible and might have a significant impact on global human health.

Serum IgG titres, but not avidity, correlates with neutralizing antibody response after H5N1 vaccination.

BACKGROUND: Influenza H5N1 virus constitutes a pandemic threat and development of effective H5N1 vaccines is a global priority. Anti-influenza antibodies directed towards the haemagglutinin (HA) define a correlate of protection. Both antibody concentration and avidity may be important for virus neutralization and resolving influenza disease. METHODS: We conducted a phase I clinical trial of a virosomal H5N1 vaccine adjuvanted with the immunostimulating complex Matrix M™. Sixty adults were intramuscularly immunized with two vaccine doses (21 days apart) of 30 µg HA alone or 1.5, 7.5 or 30 µg HA adjuvanted with Matrix M™. Serum H5 HA1-specific antibodies and virus neutralization were determined at days 0, 21, 42, 180 and 360 and long-term memory B cells at day 360 post-vaccination. The binding of the HA specific antibodies was measured by avidity NaSCN-elution ELISA and surface plasmon resonance (SPR). RESULTS: The H5 HA1-specific IgG response peaked after the second dose (day 42), was dominated by IgG1 and IgG3 and was highest in the adjuvanted vaccine groups. IgG titres correlated significantly with virus neutralization at all time points (Spearman r≥0.66, p<0.0001). By elution ELISA, serum antibody avidity was highest at days 180 and 360 post vaccination and did not correlate with virus neutralization. Long-lasting H5 HA1-specific memory B cells produced high IgG antibody avidity similar to serum IgG. CONCLUSIONS: Maturation of serum antibody avidity continued up to day 360 after influenza H5N1 vaccination. Virus neutralization correlated with serum H5 HA1-specific IgG antibody concentrations and not antibody avidity.

An H7N1 influenza virus vaccine induces broadly reactive antibody responses against H7N9 in humans.

Emerging H7N9 influenza virus infections in Asia have once more spurred the development of effective prepandemic H7 vaccines. However, many vaccines based on avian influenza viruses--including H7--are poorly immunogenic, as measured by traditional correlates of protection. Here we reevaluated sera from an H7N1 human vaccine trial performed in 2006. We examined cross-reactive antibody responses to divergent H7 strains, including H7N9, dissected the antibody response into head- and stalk-reactive antibodies, and tested the in vivo potency of these human sera in a passive-transfer H7N9 challenge experiment with mice. Although only a low percentage of vaccinees induced neutralizing antibody responses against the homologous vaccine strain and also H7N9, we detected strong cross-reactivity to divergent H7 hemagglutinins (HAs) in a large proportion of the cohort with a quantitative enzyme-linked immunosorbent assay. Furthermore, H7N1 vaccination induced antibodies to both the head and stalk domains of the HA, which is in sharp contrast to seasonal inactivated vaccines. Finally, we were able to show that both neutralizing and nonneutralizing antibodies improved in vivo virus clearance in a passive-transfer H7N9 challenge mouse model.

Should patients who use illicit drugs be offered a second heart-valve replacement?

Intravenous drug users (IVDUs) have an elevated risk of contracting infectious endocarditis. Most of them have good effect from medical treatment, but some will need valve replacement. Until a few years ago, our hospital withheld valve surgery if patients with intravenous drug dependency and infectious endocarditis came to need a second valve replacement. However, there are no consensus guidelines for treatment of this group of patients, and a dearth of data on the effects and benefits of interventions. Using a method of ethical analysis, we here discuss whether it is appropriate to offer valve surgery to drug users for a second time.

[Risk of infection through use of selective immunomodulating drugs for rheumatoid arthritis]. / Infeksjonsrisiko ved bruk av selektivt immunmodulerende midler mot revmatoid artritt.

BACKGROUND: New drugs for rheumatoid arthritis (RA) have resulted in an improvement in patients' functioning and morbidity, but are linked with increased risk of infections. Traditional immunosuppressant drugs are often used in combination with anti-tumour necrosis factor-alpha (TNF-α) inhibitors or anti-CD20 (rituximab). METHOD: The review is based on a search in PubMed and on the authors' own experience of treating infections in patients who receive immunosuppressant treatment. RESULTS: Traditional immunomodulating treatment results in an increased risk of infection. The disease RA in itself increases the risk of infections. There is evidence of an increased incidence of infections with both extracellular bacteria and intracellular microorganisms such as mycobacteria, including Mycobacterium tuberculosis, and viruses in patients who are treated with TNF-α inhibitors. Patients who are about to start taking TNF-α inhibitors must therefore undergo a tuberculosis-risk assessment. Rituximab may increase the incidence of infection, but long-term observations are limited. Combination therapy involving different drugs that selectively modulate immune response is normally contraindicated because of the increased risk of infection. INTERPRETATION: The benefit of TNF-α inhibitors and rituximab treatment for RA must be weighed up against the increased risk of infections. Symptoms, findings and laboratory test results pertaining to serious infections may be influenced by immunomodulation therapy and thereby make clinical assessment difficult.

[A man with pain following a knee operation]. / En mann med smerter etter kneoperasjon.

BACKGROUND: Infection after arthroscopy is a rare, but feared complication. Aggressive infection with atypical microbiological agents severely complicates the clinical evaluation. CASE PRESENTATION: A man in his thirties, previously healthy man had undergone elective knee arthroscopy with synovectomy. Eight days after surgery he was admitted to hospital with swelling and pain in the operated knee. Re-arthroscopy revealed bleeding in the affected joint, but no obvious signs of infection. The patient developed severe pain, fever and elevated infection parameters. Staphylococcus lugdunensis was detected in the joint fluid taken during re-arthroscopy. He was treated with a combination of antibiotics, including cloxacillin, gentamicin and linezolid, and made a full recovery after treatment. INTERPRETATION: S lugdunensis is a highly virulent, coagulase-negative staphylococcus, capable of causing significant infections. It should never be dismissed as a contaminant without careful review.

T-helper 1 cells elicited by H5N1 vaccination predict seroprotection.

BACKGROUND: Vaccination is the best measure to protect the population against a potential influenza H5N1 pandemic, but 2 doses of vaccine are needed to elicit protective immune responses. An immunological marker for H5N1 vaccine effectiveness is needed for early identification of the best vaccine candidate. METHODS: We conducted a phase I clinical trial of a virosomal H5N1 vaccine adjuvanted with Matrix M. Sixty adult volunteers were vaccinated intramuscularly with 2 doses of either 30 µg hemagglutinin (HA) alone or with 1.5, 7.5, or 30 µg HA and Matrix M adjuvant (50 µg). The humoral response was measured by the hemagglutination inhibition (HI), microneutralization (MN), and single radial hemolysis (SRH) assays, and the CD4(+) T-helper 1 (Th1)-cell response was measured by intracellular staining for the cytokines interleukin 2, interferon γ, and tumor necrosis factor α. RESULTS: The adjuvanted vaccine effectively induced CD4(+) Th1-cell responses, and the frequency of influenza-specific Th1 cells after the first vaccine dose predicted subsequent HI, MN, and SRH seroprotective responses after the second vaccination. CONCLUSIONS: These results support early identification of Th1-cell responses as a predictive biomarker for an efficient vaccine response, which could have great implications for early identification of persons with low or no response to vaccine when evaluating future pandemic influenza vaccines.