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BACKGROUND: Influenza A/H7N9 viruses have pandemic potential. METHODS: We conducted an open-label, randomized, controlled trial of AS03-adjuvanted 2017 inactivated influenza A/H7N9 vaccine (H7N9 IIV) in healthy adults. Group 1 received H7N9 IIV and seasonal quadrivalent influenza vaccine (IIV4) simultaneously, followed by H7N9 IIV three weeks later. Group 2 received IIV4 alone and then two doses of H7N9 IIV at three-week intervals. Group 3 received one dose of IIV4. We used hemagglutination inhibition (HAI) and microneutralization (MN) assays to measure geometric mean titers and seroprotection (≥1:40 titer) to vaccine strains and monitored for safety. RESULTS: Among 149 subjects, seroprotection by HAI three weeks after H7N9 IIV dose 2 was 51% (95 %CI 37%-65%) for Group 1 and 40% (95 %CI 25%-56%) for Group 2. Seroprotection by MN at the same timepoint was 84% (95 %CI 72%-93%) for Group 1 and 74% (95 %CI 60%-86%) for Group 2. By 180 days after H7N9 IIV dose 2, seroprotection by HAI or MN was low for Groups 1 and 2. Responses measured by HAI and MN against each IIV4 strain three weeks after IIV4 vaccination were similar in all groups. Solicited local and systemic reactions were similar after a single vaccination, while those receiving simultaneous H7N9 and IIV4 had slightly more reactogenicity. There were no serious adverse events or medically-attended adverse events related to study product receipt. CONCLUSIONS: Adjuvanted H7N9 IIV was modestly immunogenic whether administered simultaneously or sequentially with IIV4, though responses declined by 180 days. IIV4 was immunogenic regardless of schedule. CLINICAL TRIALS REGISTRATION: NCT03318315

We report our experience caring for an infant with respiratory syncytial virus infection (RSV) and group B Streptococcus (GBS) bacteremia and meningitis. Concurrent GBS meningitis and RSV is rare but highlights the importance of correlating clinical symptoms with viral diagnostic testing during the evaluation of infants at risk for serious bacterial infection.

Objective In response to the emergence of influenza viruses with pandemic potential, we evaluated a swine-origin influenza A/H3N2 variant (H3N2v) vaccine in children. Study design This multicenter phase II open-label study assessed the safety and immunogenicity of two doses, 21 days apart, of investigational unadjuvanted subvirion monovalent inactivated H3N2v vaccine administered via intramuscular injection. Children 6–35 months of age received 7.5mcg or 15mcg of hemagglutinin (HA)/dose; children 3–17 years of age received 15mcg HA/dose. Safety and reactogenicity were assessed by measuring the occurrence of solicited injection site and systemic reactions in the 7 days after each vaccination; adverse events were assessed for 42 days and serious adverse events for 7 months after the first vaccination. Immunogenicity was evaluated by measuring hemagglutination inhibition (HAI) and neutralizing (Neut) antibodies to H3N2v prior to and 21 days after each vaccination. Cross-reactivity against seasonal H3N2 strains was evaluated. Results The H3N2v vaccine was well tolerated. Transient mild to moderate injection site tenderness, pain and erythema was observed, with the most commonly reported systemic reactogenicity being irritability in children 6–35 months, and headache and fatigue in children 9–17 years old. Children 6–35 months old, whether they received 7.5mcg or 15mcg/dose, had low HAI and Neut antibody responses after two doses compared to older children. Children under 9 years of age required two doses of vaccine to demonstrate a response, while 9–17 year olds responded well after one dose. Previous influenza vaccination and older age were associated with higher immune responses to H3N2v vaccine. Children 9–17 years of age also developed cross-reactive antibodies against recent seasonal H3N2 influenza viruses. Conclusion The H3N2v vaccine was safe and immunogenic in children and adolescents. Age-related increases in immunogenicity against H3N2v and seasonal H3N2 viruses were observed, suggesting prior priming via infection and/or immunization. Clinical trial registry: The trial is registered with clinicaltrial.gov: NCT02100436 .

Objectives To characterize Staphylococcus aureus isolates recovered from hospitalized children and to determine the concordance between colonizing and invasive isolates. Study design Children with culture-confirmed, community-onset, invasive S aureus infections were enrolled in this prospective case series from a large children's hospital over a 5-year period. Colonization isolates were obtained from the anterior nares, oropharynx, and inguinal folds and were compared with invasive isolates via repetitive-element, sequence-based polymerase chain reaction testing. Isolates with a ≥96% genetic match were characterized as concordant. Results A total of 86 S aureus isolates (44 invasive, 42 colonization) were collected from 44 children with invasive infections. Clinical isolates were genetically diverse, 64% of invasive isolates were methicillin-susceptible S aureus (MSSA), and 59% of cases had a colonizing S aureus isolate at the time of hospitalization. Of those who were colonized, at least 1 of their colonization isolates was indistinguishable from the infecting isolate in 88% of cases. Patients with invasive MSSA were significantly more likely to have a concordant MSSA colonization isolate present compared with patients with invasive methicillin-resistant S aureus (MRSA) (61% vs 38%, P Conclusions Invasive MSSA infection was more common than MRSA infection in this pediatric cohort, and patients with MSSA infection were significantly more likely than those with MRSA infection to have concordant colonizing isolates across multiple anatomic sites. These findings warrant larger scale validation and may have important infection control and epidemiologic implications, as unlike MRSA, transmissibility of MSSA largely is ignored in healthcare settings.

A detailed understanding of the adaptive host response to SARS-CoV-2 infection in humans is urgently needed, as questions abound regarding serologic responses and the development of antibody-mediated immunity against COVID-19. We developed a highly sensitive, high-throughput, and efficient assay using liquid bead array technology. We observed advantages over traditional indirect ELISA for the detection and quantification of binding IgG against the receptor binding domain (RBD) of SARS-CoV-2. Using this sensitive and highly reproducible assay, we sought to determine whether the severity of COVID-19 symptoms is correlated with SARS-CoV-2 binding IgG level. We measured SARS-CoV-2 RBD IgG levels from 67 subjects who had recovered from PCR-confirmed, symptomatic COVID-19. Samples were obtained approximately 6 weeks post-symptom onset. We found that COVID-19 symptom severity, assessed on an 8-point severity scale, strongly correlated with RBD IgG level (p

To understand the epidemiology of acute hematogenous osteomyelitis and septic arthritis, including clinical and demographic features, microbiology, treatment approaches, treatment-associated complications, and outcomes.Retrospective cohort study of 453 children with acute hematogenous osteomyelitis and/or septic arthritis from 2009 to 2015.Among the 453 patients, 218 (48%) had acute hematogenous osteomyelitis, 132 (29%) had septic arthritis, and 103 (23%) had concurrent acute hematogenous osteomyelitis/septic arthritis. Treatment failure/recurrent infection occurred in 41 patients (9%). Patients with concurrent acute hematogenous osteomyelitis/septic arthritis had longer hospital stays, longer duration of antibiotic therapy, and were more likely to have prolonged bacteremia and require intensive care. Staphylococcus aureus was identified in 228 (51%) patients, of which 114 (50%) were methicillin-resistant S aureus. Compared with septic arthritis, acute hematogenous osteomyelitis and concurrent acute hematogenous osteomyelitis/septic arthritis were associated with higher odds of treatment failure (OR, 8.19; 95% CI, 2.02-33.21 [P = .003]; and OR, 14.43; 95% CI, 3.39-61.37 [P .001], respectively). The need for more than 1 surgical procedure was also associated with higher odds of treatment failure (OR, 2.98; 95% CI, 1.18-7.52; P = .021). Early change to oral antibiotic therapy was not associated with treatment failure (OR, 0.64; 95% CI, 0.24-1.74; P = .386). Most (73%) medically attended treatment complications occurred while on parenteral therapy.Musculoskeletal infections are challenging pediatric infections. S aureus remains the most common pathogen, with methicillin-resistant S aureus accounting for 25% of all cases. Concurrent acute hematogenous osteomyelitis/septic arthritis is associated with more severe disease and worse outcomes. Fewer treatment-related complications occurred while on oral therapy. Early transition to oral therapy was not associated with treatment failure.

Background The decline in immune function with age is a challenge to vaccine development. Following an initial study in adults aged 18–64 years, this study evaluated the safety and immunogenicity of Staphylococcus aureus (S. aureus) 4-antigen (SA4Ag) and 3-antigen (SA3Ag) vaccine in older adults. SA3Ag included capsular polysaccharide serotypes 5 and 8 (CP5 and CP8) conjugated to the nontoxic mutant form of diphtheria toxin (CRM197) and a recombinant version of clumping factor A (ClfA). SA4Ag included these antigens, with the addition of a recombinant manganese transporter C (rP305A or MntC). Both vaccines were unadjuvanted. Methods In this double-blind, sponsor-unblinded, placebo-controlled, phase 1/2 study, 284 healthy adults (aged 65–85 years) were randomised to receive a single dose of one of three formulations of SA4Ag with escalating dose levels of rP305A, SA3Ag, or placebo. Functional immune responses were measured using opsonophagocytic activity (OPA) killing and fibrinogen-binding inhibition (FBI) assays; immunogenicity was also assessed using a competitive Luminex® immunoassay (cLIA). T-cell responses were measured in a small subgroup of subjects using intracellular cytokine staining (ICS) assays. Results The results demonstrated rapid and robust functional immune responses to all antigens in healthy older adults. A high proportion of active vaccine recipients met the pre-defined antibody thresholds for each antigen at Day 29. SA4Ag elicited a dose-level response to rP305A with up to a 13-fold rise in cLIA titres at Day 29. Opsonophagocytic activity (OPA) assays showed >50- and >20-fold rises in functional titres using S. aureus strains expressing CP5 and CP8, respectively, at Day 29. T-cell cytokine responses were not substantially above background levels. There were no safety concerns in this study population and no increases in adverse events with higher rP305A dose levels. Conclusions Single-dose vaccination of SA4Ag and SA3Ag in healthy adults aged 65–85 years safely induced rapid and robust functional immune responses, supporting further development of SA4Ag for the prevention of S. aureus disease in adults up to age 85 years. Trial registration number: NCT01643941 .

Background A prophylactic Staphylococcus aureus four-antigen vaccine (SA4Ag) is under development for prevention of invasive S. aureus disease. A preliminary S. aureus three-antigen vaccine (SA3Ag) was reformulated to include a novel manganese transporter protein (MntC or rP305A). This study describes the first-in-human dose-finding, safety, and immunogenicity results for SA4Ag. Methods In this double-blind, sponsor-unblind, placebo-controlled, phase 1/2 study, 454 healthy adults aged 18–64 years were randomised to receive a single dose of one of three formulations of SA4Ag with escalating dose levels of rP305A or placebo. Functional immune responses were measured using opsonophagocytic activity (OPA) killing and fibrinogen-binding inhibition (FBI) assays; antigen-specific immunogenicity was assessed using a four-plex competitive Luminex® immunoassay (cLIA). Results A high proportion of SA4Ag recipients met the pre-defined antibody thresholds for each antigen at Day 29. A substantial and dose-level dependent immune response was observed for rP305A, with up to 18-fold rises in cLIA titres at Day 29. Robust functional responses were demonstrated, with >80-fold and >20-fold rises in OPA assay titres at Day 29 using S. aureus strains expressing capsular polysaccharide serotypes 5 and 8, respectively. Durable antibody responses were observed through month 12, gradually waning from peak levels achieved by days 11–15. SA4Ag was well tolerated, and no vaccine-related serious adverse events were reported. Conclusions Single-dose vaccination of SA4Ag in healthy adults aged 18–64 years safely induced rapid and robust functional immune responses that were durable through month 12, supporting further development of this vaccine. Trial registration number: NCT01364571

Chronic granulomatous disease (CGD), a disease characterized by inadequate neutrophil killing of microbial pathogens, affects 4 to 5 per million live births. For many decades following its description, CGD was a fatal disease in childhood. With the development of effective preventive therapies and the early recognition of infectious complications, 90% of children with CGD now survive into adulthood. The management of CGD in adults includes unique challenges and potential disease manifestations. In this article, the authors discuss the current approach to the management of CGD in both children and adults. This includes a focus on the importance of a comprehensive multidisciplinary approach in the care of CGD and its potential complications. In addition, a novel approach to improving education about CGD, and subsequently improving adherence to preventive therapies, is discussed.

Summary A detailed understanding of the adaptive host response to SARS-CoV-2 infection in humans is urgently needed. We developed a sensitive, high-throughput, and efficient assay using liquid bead array technology. We observed advantages over traditional ELISA for the detection and quantification of binding IgG against the receptor binding domain (RBD) of SARS-CoV-2. To determine whether COVID-19 symptom severity correlates with SARS-CoV-2 IgG, we measured anti-RBD IgG levels from 67 subjects recovered from PCR-confirmed COVID-19. We found that COVID-19 symptom severity strongly correlated with RBD IgG level (p < 0.001). These findings have substantial implications for public policy surrounding assessments of antibody responses and possible immunity, as not all cases of COVID-19 can be assumed to generate a protective antibody response, and mild disease in particular is capable of generating very low-level anti-RBD IgG levels. These findings also have important implications for the selection of donors for convalescent plasma to be used therapeutically., Graphical abstract, Highlights • We developed a sensitive, high-throughput assay for quantification of SARS-CoV-2 IgG • The assay uses liquid bead array technology for efficient and reproducible results • COVID-19 symptom severity was strongly correlated with SARS-CoV-2 SRBD IgG levels, Biological Sciences; Microbiology; Virology; Viral Microbiology

Background Staphylococcus aureus is one of the earliest bacterial pathogens to colonize the lungs of children with cystic fibrosis and is an important contributor to pulmonary exacerbations. The adaptive host response to S. aureus in cystic fibrosis remains inadequately defined and has important implications for pathogenesis and potential interventions. The objectives of this study were to determine the functional antibody response to select staphylococcal exotoxins (LukAB, alpha-hemolysin, and PVL) in children with cystic fibrosis and to evaluate the relationship of this response with pulmonary exacerbations. Methods Fifty children with cystic fibrosis were enrolled and followed prospectively for 12months. Clinical characteristics and serologic profiles were assessed at routine visits and during pulmonary exacerbations, and functional antibody assessments were performed to measure neutralization of LukAB-mediated cytotoxicity. Results For each antigen, geometric mean titers were significantly higher if S. aureus was detected at the time of exacerbation. For LukAB, geometric mean titers were significantly higher at exacerbation follow-up compared to titers during the exacerbation, consistent with expression during human disease, and the humoral response capably neutralized LukAB-mediated cytotoxicity. Moreover, the presence of a positive S. aureus culture during a pulmonary exacerbation was associated with 31-fold higher odds of having a LukA titer ≥1:160, suggesting potential diagnostic capability of this assay. Conclusions The leukotoxin LukAB is expressed by S. aureus and recognized by the human adaptive immune response in the setting of pulmonary infection in cystic fibrosis. Anti-LukAB antibodies were not only predictive of positive staphylococcal culture during exacerbation, but also functional in the neutralization of this toxin.

Purpose The study aims were to determine whether inactivated influenza A/H5N1 vaccine administration elicited cell mediated immune (CMI) responses and the impact of adjuvant, vaccine dose and subject age on these responses. Methods Adults who were previously primed with either adjuvanted or unadjuvanted, inactivated, A/H5N1/Vietnam/1203/2004 (Clade 1) vaccine or unprimed (received placebo) in previous vaccine studies were randomized to receive one (primed) or two (unprimed) 15- or 90-mcg doses of inactivated, A/H5N1/Indonesia/05/05 (Clade 2) vaccine. Peripheral blood mononuclear cells (PBMCs) were collected and analyzed from a subset of vaccinees to assess CMI responses using IFN-γ and granzyme B ELISPOT assays. Cytokine measurements were performed on PBMC supernatants after stimulation with H5N1 virus. Results PBMCs were available from 177 participants; 88 and 89 received 15-mcg and 90-mcg of unadjuvanted clade 2 vaccine, respectively. Following H5N1 clade 1 stimulation, IFN-γ but not granzyme B normalized spot-forming cell numbers had statistically significant increased numbers at each of the post-vaccination timepoints compared to baseline in pooled analyses of all vaccine doses and age groups. Clade 2 stimulation resulted in statistically significant increased numbers of IFN-γ cells only 180 days following the last vaccination. Responses were similar among younger and older study participants, as were responses among those primed with alum-adjuvanted or non-adjuvanted clade 1 H5N1 vaccines. The dosage of clade 2 vaccine did not impact CMI responses among primed subjects, but responses were statistically significantly greater in unprimed recipients of the 90-mcg dosage compared to unprimed recipients of the 15-mcg dosage. IFN-γ levels in the supernatants of stimulated PBMC were strongly correlated with IFN-γ ELISPOT results. Conclusion CMI responses occur in adults administered influenza A/H5N1 inactivated influenza vaccine.

Summary H7N9 avian influenza virus causes severe infections and might have the potential to trigger a major pandemic. Molecular determinants of human humoral immune response to N9 neuraminidase (NA) proteins, which exhibit unusual features compared with seasonal influenza virus NA proteins, are ill-defined. We isolated 35 human monoclonal antibodies (mAbs) from two H7N9 survivors and two vaccinees. These mAbs react to NA in a subtype-specific manner and recognize diverse antigenic sites on the surface of N9 NA, including epitopes overlapping with, or distinct from, the enzyme active site. Despite recognizing multiple antigenic sites, the mAbs use a common mechanism of action by blocking egress of nascent virions from infected cells, thereby providing an antiviral prophylactic and therapeutic protection in vivo in mice. Studies of breadth, potency, and diversity of antigenic recognition from four subjects suggest that vaccination with inactivated adjuvanted vaccine induce NA-reactive responses comparable to that of H7N9 natural infection.

Staphylococcus aureus infections pose a significant health burden. The emergence of community-associated methicillin-resistant S. aureus has resulted in an epidemic of skin and soft tissue infections (SSTI), and many patients experience recurrent SSTI. As S. aureus colonization is associated with subsequent infection, decolonization is recommended for patients with recurrent SSTI or in settings of ongoing transmission. S. aureus infections often cluster within households and asymptomatic carriers serve as reservoirs for transmission; therefore, a household approach to decolonization is more effective than measures performed by individuals alone. Other factors, such as environmental surface contamination, may also be considered. Novel strategies for the prevention of recurrent SSTI are needed.

Summary Adaptations that enable antimicrobial resistance often pose a fitness cost to the microorganism. Resistant pathogens must therefore overcome such fitness decreases to persist within their hosts. Here we demonstrate that the reduced fitness associated with one resistance-conferring mutation can be offset by community interactions with microorganisms harboring alternative mutations or via interactions with the human microbiota. Mutations that confer antibiotic resistance in the human pathogen Staphylococcus aureus led to decreased fitness, whereas coculture or coinfection of two distinct mutants resulted in collective recovery of fitness comparable to that of wild-type. Such fitness enhancements result from the exchange of metabolites between distinct mutants, leading to enhanced growth, virulence factor production, and pathogenicity. Interspecies fitness enhancements were also identified, as members of the human microbiota can promote growth of antibiotic-resistant S. aureus. Thus, inter- and intraspecies community interactions offset fitness costs and enable S. aureus to develop antibiotic resistance without loss of virulence.

This paper evaluates the ability to detect three forms of methicillin-resistant Staphylococcus aureus (MRSA) in a microfluidic system. The MRSA was prepared off-chip by varying levels of sample preparation: one containing purified genomic DNA, another containing the supernatant of a crude preparation using simple reagents, and a third through boiled culture preparation without any additional reagents. Polydimethylsiloxane (PDMS) microfluidic chips were fabricated using soft lithography and then bonded to a 22mmx22mmx0.1mm glass cover slip. A lid fabricated in a similar manner was used during compression to prevent bubble formation and evaporation in the stationary well-based chip. A miniature thermal cycler based on a resistive heater and a small fan were used to cycle through desired temperatures for polymerase chain reaction and fluorescent intensity measurements were taken at each cycle. Each form of template provided positive results utilizing the developed micro-PCR system (verified with gel electrophoresis). A serial dilution of the purified genomic DNA provided a standard curve with an efficiency of 1.77. The lowest concentration that provided clear positive results came from a 3microL sample containing 11.2pg of DNA. The ability to detect MRSA in a sample having undergone minimal sample preparation is a necessary step in the development of a point-of-care detection system capable of identifying infectious organisms.

Background There is a critical need for an effective Staphylococcus aureus vaccine for the prevention of staphylococcal disease. In this study, we investigated the impact of S. aureus conjugate vaccine comprised of capsular polysaccharides 5 and 8 (CP5, CP8) on nasal colonization with S. aureus . Methods Healthy adults recruited from one academic medical center to participate in a lot consistency trial of StaphVAX ® ( S. aureus capsular polysaccharide 5 and 8 conjugate vaccine) were assessed for S. aureus nasal colonization at two weekly points prior to vaccination and again at six weeks post-vaccination. Serum anti-capsular antibody titers to CP5 and CP8 were obtained prior to vaccination and 42 days post-vaccination and measured by ELISA. Results Thirty of 88 enrolled subjects (34%) had S. aureus isolated from at least one of the pre-immunization cultures. Of these, 20 were termed persistent carriers due to two positive cultures one week apart; 19 of the 20 were evaluable at Day 42. Baseline anti-CP8 concentrations were higher in persistent carriers of CP8+ S. aureus ; however, baseline anti-CP5 levels were not significantly higher in individuals persistently colonized with CP5+ S. aureus . Statistically significant rises in antibody concentrations were noted after vaccination. At Day 42, 14 of 19 persistent carriers remained colonized; 5 subjects did not have evidence of S. aureus colonization. Ten additional subjects were positive for S. aureus at Day 42 who were not persistently colonized at baseline. Serum antibody concentrations were not statistically different between those with persistent carriage vs. those that lost carriage or those with newly acquired carriage. Conclusions Immune responses to vaccine were brisk and comparable in subjects with or without persistent colonization. Despite a substantial rise in anti-CP5 and anti-CP8 antibody concentrations post-vaccination, S. aureus nasal colonization rates did not significantly change.