BackgroundAlthough pre-transplant immunization is routinely recommended, this recommendation is based on little data. The primary objective of this study was to compare antibody responses in lung transplant patients who received influenza vaccine before the transplant, within the first six months of transplant, between 13 and 60 months post-transplant, and 110 months or beyond transplant.MethodsThis prospective cohort study included 357 total immunization events performed over five yr to measure H1N1, H3N2, and B antibody responses to the influenza vaccine in pre- and post-lung transplant patients. Geometric mean titers, seroprotection (antibody titer at least 1:40), seroconversion (fourfold increase between pre and post), and mean fold increases were compared.ResultsThe geometric mean titer distributions were different for H3N2 and B (ANOVA; p = 0.002 for both). Pre-transplant antibody concentrations were higher compared to the 13- to 60-month group for H3N2 (corrected p = 0.002) and the healthy group for B (corrected p = 0.001). The 110-month group had higher seroconversion rates compared to the 13- to 60-month group for H3N2 and B viruses.ConclusionLung pre-transplant patients and the long-term survivors have higher responses to the influenza vaccine than early post-transplant and the transplant control groups.

Background. Lung transplant recipients are among those with the highest risk of influenza infection and complications each year. A few studies show adequate responses after influenza immunization; no studies examined the season-long protection. Methods. Influenza antibody concentrations were measured using hemagglutination inhibition assays before immunization, 2 to 4 weeks after immunization, and 6 months after immunization in 25 healthy controls and 54 lung transplant patients. Two definitions of seroprotection (40 hemagglutination units (HAU) and 160 HAU which confers about 95% protection) were used. Results. Influenza vaccine responses were high in both groups postimmunization (100% at 40 HAU and 60% healthy and 61% lung transplant at 160 HAU; P = 1.0; chi-square). At 6 months after immunization, seroprotection rates at 40 HAU (95% healthy and 97% lung transplant; P = 1.0) and at 160 HAU (24% healthy and 36% lung transplant; P = 0.40) were observed. Conclusion. Seroprotection rates do not differ between healthy and transplant groups over 6 months when 40 HAU or 160 HAU is used. However, the seroprotection rates are disappointingly low when 160 HAU (the antibody concentration associated with 95% protection from infection) is used. Annual influenza vaccine should continue to be a high priority for lung transplant patients.

Background: The timing of influenza vaccination and susceptibility to re-circulating virus in the population is influenced by the persistence of seroprotection. Immunosuppressed transplant patients are known to have lower antibody response rates than healthy individuals, but acceptable antibody concentrations are achieved. The duration of this seroprotection beyond a single season has not been evaluated in either healthy or immunosuppressed populations. Methods: Influenza antibody concentrations against viruses no longer included in the vaccine were measured in serum by hemagglutination inhibition assay annually following vaccination of 73 lung transplant participants and 27 healthy controls. Seroprotection was defined as a titer of ≥ 1:40 and was compared between groups over the measured term using Fisher’s exact tests. Results: Seroprotection rates for influenza A and B strains at one year following immunization were 100% for lung transplant and healthy controls. Rates at two years for the influenza A strains were 65–74% for lung transplant vs. 77–100% in healthy controls. Rates for influenza B strains two years following immunization were 27–50% for lung transplant vs. 16–38% in healthy controls. (Fisher’s exact test; not significant for between group comparisons; p < 0.05 for between season comparisons) Conclusions: Vaccine-induced antibody persistence appears to be influenced more by the vaccine virus strain than the immune status of the vaccinated individuals. Seroprotection rates are high 12 mo following influenza vaccination but wane over the second year, particularly for influenza B viruses. Annual influenza immunization is indicated, even for healthy individuals and even when the vaccine viruses do not change.

ABSTRACT Methicillin-resistant Staphylococcus aureus (MRSA) isolates that are susceptible to vancomycin but are tolerant to its killing effect may present a potential challenge for effective treatment. This study compared the microbiologic characteristics of clinical vancomycin-tolerant (VT-MRSA) and vancomycin-susceptible (VS-MRSA) strains using phenotypic and gene regulation studies. MRSA isolates collected from vancomycin-treated patients with bacteremia over a 5-year period were analyzed for vancomycin, daptomycin, and telavancin susceptibility, as well as accessory gene regulator ( agr ) group and function. Vancomycin tolerance was defined by a minimum bactericidal concentration (MBC)/minimum inhibitor concentration (MIC) ratio of ≥32 mg/liter. VT-MRSA isolates were compared to VS-MRSA isolates for differences in antimicrobial susceptibility, time-kill activity, and gene expression of key cell envelope response genes vraSR , dltA , and mprF . All 115 isolates evaluated were susceptible to vancomycin, daptomycin, and telavancin. Seven isolates (6%) were VT-MRSA. agr group II was more prevalent in isolates with vancomycin MBC/MIC ratios of ≥8. In time-kill analyses, VT-MRSA had reduced vancomycin killing, but daptomycin and telavancin activities were maintained. Significantly greater gene expression was observed in VT-MRSA after 72 h of subinhibitory antibiotic exposures. Vancomycin most notably increased vraSR expression ( P = 0.002 versus VS-MRSA strains). Daptomycin and telavancin increased expression of all genes studied, most significantly mprF expression ( P < 0.001). Longer durations of antibiotic exposure (72 h versus 24 h) resulted in substantial increases in gene expression in VT-MRSA. Although the clinical impact of VT-MRSA is not fully recognized, these data suggest that VT-MRSA strains, while still susceptible, have altered gene regulation to adapt to the antimicrobial effects of glyco- and lipopeptides that may emerge during prolonged durations of exposure.

BACKGROUND:Toxins contribute to the pathogenicity of Staphylococcus aureus infections by inducing a dysregulated inflammatory response. This study evaluated the impact of anti-staphylococcal antibiotic exposures over an increasing concentration range on cytokine production from peripheral blood mononuclear cells (PBMCs) after S. aureus toxin exposures.METHODS:Human PBMCs were suspended in complete Roswell Park Memorial Institute (RPMI) 1640 medium with 10% fetal bovine serum at 10(6) cells/mL with 100 ng/mL S. aureus toxic shock syndrome toxin-1 (TSST-1), staphylococcal enterotoxin A (SEA), α-toxin or Panton-Valentine leucocidin (PVL). Vancomycin, trimethoprim/sulfamethoxazole, tigecycline, daptomycin, linezolid, clindamycin and azithromycin were added at a concentration range of 0.5-100 mg/L. Cytokine [interleukin-1β (IL-1β), IL-6, IL-8, interferon-γ (IFN-γ) and tumour necrosis factor-α (TNF-α)] concentrations were measured in duplicate by ELISA following exposure and were compared with response with toxin alone.RESULTS:At concentrations approximating serum C(max), tigecycline decreased IL-6 by 52%-57% and IFN-γ production by 43%-53% compared with toxin alone (P ≤ 0.05) and linezolid inhibited TNF-α by 12%-35% and IL-8 by 25%-42% (P ≤ 0.02). However, trimethoprim/sulfamethoxazole increased TNF-α and IL-8 production (P = 0.002). Clindamycin, daptomycin, vancomycin and azithromycin had no consistent significant effect at approximate serum C(max) concentrations. All antibiotics had a concentration-dependent effect on cytokine production, with tigecycline, clindamycin and trimethoprim/sulfamethoxazole being the most potent inhibitors of cytokine production at concentrations exceeding 25 mg/L.CONCLUSIONS:S. aureus toxins stimulate production of inflammatory cytokines in PBMCs. Antimicrobials with high tissue penetration, including tigecycline, clindamycin, trimethoprim/sulfamethoxazole and linezolid, reduced cytokine production, which, along with their antimicrobial effects, may have importance in the therapeutic outcome of severe infections.

Background: Xanthine oxidase is a major source of superoxide in the vascular endothelium. Previous work in humans demonstrated improved conduit artery function following xanthine oxidase inhibition in patients with obstructive sleep apnea. Objectives: To determine whether impairments in endothelium-dependent vasodilation produced by exposure to chronic intermittent hypoxia are prevented by in vivo treatment with allopurinol, a xanthine oxidase inhibitor. Methods: Sprague-Dawley rats received allopurinol (65 mg/kg/day) or vehicle via oral gavage. Half of each group was exposed to intermittent hypoxia (FIO2 = 0.10 for 1 min, 15×/h, 12 h/day) and the other half to normoxia. After 14 days, gracilis arteries were isolated, cannulated with micropipettes, and perfused and superfused with physiological salt solution. Diameters were measured before and after exposure to acetylcholine (10–6M) and nitroprusside (10–4M). Results: In vehicle-treated rats, intermittent hypoxia impaired acetylcholine-induced vasodilation compared to normoxia (+4 ± 4 vs. +21 ± 6 µm, p = 0.01). Allopurinol attenuated this impairment (+26 ± 6 vs. +34 ± 9 µm for intermittent hypoxia and normoxia groups treated with allopurinol, p = 0.55). In contrast, nitroprusside-induced vasodilation was similar in all rats (p = 0.43). Neither allopurinol nor intermittent hypoxia affected vessel morphometry or systemic markers of oxidative stress. Urinary uric acid concentrations were reduced in allopurinol- versus vehicle-treated rats (p = 0.02). Conclusions: These data confirm previous findings that exposure to intermittent hypoxia impairs endothelium-dependent vasodilation in skeletal muscle resistance arteries and extend them by demonstrating that this impairment can be prevented with allopurinol. Thus, xanthine oxidase appears to play a key role in mediating intermittent hypoxia-induced vascular dysfunction.

Study Objective. To determine whether T‐cell immune responses to influenza vaccination in patients with chronic heart failure (CHF) are less vigorous than the responses of healthy control subjects.Design. Prospective, single‐center studySetting. University hospital and research laboratoryParticipants. Eighteen adults with stable CHF receiving optimal treatment and 16 healthy control subjects.Intervention. Participants were immunized with the 2006–2007 trivalent inactivated (killed) influenza vaccine during October‐December of 2006.Measurements and Main Results. Blood samples were taken from the participants before and 2–4 weeks after vaccination to measure antibody titers, which were measured with a hemagglutination inhibition assay, then 3–4 months after vaccination to assess T‐cell responses, measured by using the trans vivo delayed‐type hypersensitivity method. As part of this method, which mimics physiologic conditions, peripheral blood mononuclear cells were isolated from the blood samples. The cells were mixed with influenza vaccine antigens A/H1N1, A/H3N2, and B type and injected into the footpads of SCID mice (mice with severe combined immunodeficiency), as their resulting swelling is an index of human T‐cell sensitization. Median T‐cell‐mediated immune responses to A/H3N2 were less vigorous in patients with CHF than in control subjects (62.5 vs 87.5 μm, unadjusted p=0.031, age‐adjusted p=0.006). Median responses to A/H1N1 were not significantly different between the groups (56.3 vs 75 μm, p=0.11). Median responses to B type were also similar between the groups (62.5 vs 75 μm, p=0.47). All participants mounted an antibody response to the influenza vaccine.Conclusion. Patients with CHF had reduced T‐cell responses to the influenza vaccine compared with healthy control subjects, as demonstrated by a lower response to A/H3N2, the newest antigen in the 2006–2007 vaccine. However, differences in T‐cell immune responses to the A/H1N1 and B type strains were not found to be significant between the two groups, which suggests that patients with CHF can mount an appropriate response to vaccine antigens to which they have been previously exposed, but less so to new antigens. These findings suggest that patients with CHF may be at increased risk for influenza infection, and clinicians may want to investigate other or additional strategies for influenza vaccination.

Background Influenza viral infections cause significant morbidity and mortality each season. Lung transplant patients may be at higher risk because of their underlying pathophysiology. Although annual immunization is the standard of care, its efficacy remains largely unproven. Previous studies showed poor antibody response to influenza vaccine in lung transplant patients, but no data on the antibody response in consecutive seasons have been published. Methods We studied antibody responses to influenza vaccine in 122 subjects: 66 lung transplant recipients, 28 control subjects, and 28 patients awaiting lung transplantation. We compared antibody response rates to individual viruses contained in influenza vaccines in consecutive years within the 3 groups. Serum antibody concentrations were measured at baseline and 2 to 4 weeks after vaccination by using the hemagglutination inhibition assay. Log-transformed antibody concentrations and incidence of serconversion and seroprotection were calculated. Results Median log-transformed antibody responses were similar in consecutive seasons in lung transplant subjects. Incidences of seroprotection and seroconversion did not differ between consecutive seasons in lung transplant recipients. Conclusions Antibody responses were similar in consecutively measured years in lung transplant subjects. Annual influenza vaccination in lung transplant subjects produces similar immune responses in 2 consecutive years, indicating that these patients are not at significantly increased risk of vaccine failure.

Insulin resistance is prevalent in heart failure (HF) patients, and beta2 adrenergic receptors (β2-AR) are involved in glucose homeostasis. We hypothesized that β2-AR Gln27Glu and Arg16Gly polymorphisms affect insulin resistance in HF patients, and we explored if effects of β2-AR polymorphisms on glucose handling are modified by choice of beta blocker. We studied 30 nondiabetic adults with HF and a history of systolic dysfunction; 15 were receiving metoprolol succinate, and 15 were receiving carvedilol. We measured fasting glucose, insulin, and insulin resistance, and we determined β2-AR genotypes at codons 27 and 16. The cohort was insulin resistant with a mean HOMA-IR score of 3.4 (95% CI, 2.3 to 4.5; normal value, 1.0). Patients with the Glu27Glu genotype exhibited higher insulin and HOMA-IR compared to individuals carrying a Gln allele (P = 0.019). Patients taking carvedilol demonstrated lower insulin resistance if also carrying a wild-type allele at codon 27 (fasting insulin, 9.8 ± 10.5 versus 20.5 ± 2.1 for variant, P = 0.072; HOMA-IR, 2.4 ± 2.7 versus 5.1 ± 0.6, P = 0.074); those on metoprolol succinate had high insulin resistance irrespective of genotype. The β2-AR Glu27Glu genotype may be associated with higher insulin concentrations and insulin resistance in patients with HF. Future studies are needed to confirm whether treatment with carvedilol may be associated with decreased insulin and insulin resistance in β2-AR codon 27 Gln carriers.

Introduction: Insulin resistance (IR) is a common co-morbid condition in patients with heart failure (HF). The failing heart exhibits differing adrenergic receptor density, potentially increasing importance of β2 driven activities. We previously showed that β2-adrenergic receptor (ADRB2) polymorphisms influence β2-mediated glucose production more in HF patients. Whether ADRB2 polymorphisms affect IR in the setting of HF is unknown. Hypothesis: This study tests the hypothesis that ADRB2 Arg16Gly and Glu27Gln polymorphisms affect IR after beta-blocker titration in individuals with heart failure. Methods: We studied 30 non-diabetic HF patients (21 males, 9 females), titrated to maximally tolerated beta blocker doses. We measured fasting blood glucose, insulin, and IR using the HOMA-IR equation. Genotyping of ADRB2 polymorphisms was performed with PCR followed by pyrosequencing at codons 16 and 27. Results: Mean age was 56.5 ± 15.1 years. HF was ischemic (N = 11), non-ischemic (N = 9), and idiopathic (N = 10). Mean HOMA-IR score was 3.5, indicating a high prevalence of insulin resistance in this cohort. Subjects homozygous at codon 27 (Glu27Glu) demonstrated higher fasting glucose, insulin, and HOMA-IR compared to individuals carrying a Gln allele (Table). Subjects taking metoprolol succinate exhibited higher fasting glucose compared to those taking carvedilol (108 ± 14.6 versus 98 ± 9.4 mg/dL, p = 0.033), and there was a trend toward a worse insulin resistance with metoprolol succinate (HOMA-IR: 3.74 ± 2.93 versus 2.82 ± 2.6, p = 0.2). The ADRB2 Arg16Gly variant was not associated with significant differences in glucose values. Conclusions: The ADRB2 Glu27Gln variant affects IR in HF patients taking beta-blockers. Choice of beta blocker therapy influences IR as well. Larger studies should examine interactions between these effects to minimize deleterious effects of therapy on glucose metabolism in HF patients.Tabled 1Metabolic Values Based on Arg16Gly and Glu27Gln StatusADRβ2 GenotypeGly16GlyGlu27GluHomozygousYNP-value∗YNP-valueFasting Glucose (mg/dL)101.4 ± 11.0102.8 ± 12.00.38106 ± 3.794 ± 13.50.05Fasting Insulin (μIU/mL)15.2 ± 15.011.9 ± 7.40.2716.5 ± 6.610.2 ± 9.40.045HOMA-IR∗∗3.59 ± 2.53.36 ± 3.30.434.53 ± 2.12.95 ± 1.90.07- Values are mean ± SD ∗ Comparison between homozygous and heterozygous individuals ∗∗ HOMA-IR = Homeostasis model assessment of insulin resistance. Open table in a new tab - Values are mean ± SD ∗ Comparison between homozygous and heterozygous individuals ∗∗ HOMA-IR = Homeostasis model assessment of insulin resistance.