Search

As the influenza A H1N1 pandemic emerged in 2009, children were found to experience high morbidity and mortality and were prioritized for vaccination. This multicenter, randomized, double-blind, age-stratified trial assessed the safety and immunogenicity of inactivated influenza A(H1N1)pdm09 vaccine in healthy children aged 6 months to 17 years.Children received 2 doses of approximately 15 or 30 µg hemagglutin antigen 21 days apart. Reactogenicity was assessed for 8 days after each dose, adverse events through day 42, and serious adverse events or new-onset chronic illnesses through day 201. Serum hemagglutination inhibition titers were measured on days 0 (prevaccination), 8, 21, 29 and 42.A total of 583 children received the first dose and 571 received the second dose of vaccine. Vaccinations were generally well-tolerated and no related serious adverse events were observed. The 15 µg dosage elicited a seroprotective hemagglutination inhibition (≥ 1:40) in 20%, 47% and 93% of children in the 6-35 month, 3-9 year and 10-17 year age strata 21 days after dose 1 and in 78%, 82% and 98% of children 21 days after dose 2, respectively. The 30 µg vaccine dosage induced similar responses.The inactivated influenza A(H1N1)pdm09 vaccine exhibited a favorable safety profile at both dosage levels. While a single 15 or 30 µg dose induced seroprotective antibody responses in most children 10-17 years of age, younger children required 2 doses, even when receiving dosages 4- to 6-fold higher than recommended. Well-tolerated vaccines are needed that induce immunity after a single dose for use in young children during influenza pandemics.

Malaria results in over 650,000 deaths each year; thus, there is an urgent need for an effective vaccine. Pre-clinical studies and recently reported human trials suggest that pre-erythrocytic stage vaccines can provide protection against infection. A Phase 1, randomized, placebo-controlled, dose-escalation study was conducted with a vaccine composed of a replication-deficient adenovirus-35 backbone with P. falciparum circumsporozoite (CS) surface antigen (Ad35.CS.01). Healthy adult subjects received three doses of 10 (8), 10 (9), 10 (10), or 10 (11) vp/mL Ad35.CS.01 vaccine or saline placebo intramuscularly at 0, 1, and 6-mo intervals. Adverse events were assessed and anti-CS antibody responses were determined by ELISA. Seventy-two individuals were enrolled, with age, gender, and ethnicity similar across each study arm. While the vaccine was generally well tolerated, adverse events were more frequent in the highest dose groups (10 (10) and 10 (11) vp/mL). More robust humoral responses were also noted at the highest doses, with 73% developing a positive ELISA response after the three dose series of 10 (11) vp/mL. The Ad35.CS.01 vaccine was most immunogenic at the highest dosages (10 (10) and 10 (11) vp/mL). Reactogenicity findings were more common after the 10 (11) vp/mL dose, although most were mild or moderate in nature and resolved without therapy.

The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) disease in neonatal intensive care units has risen sharply in recent years. Prevention of MRSA infection is of utmost importance given the high virulence and broad antibiotic resistance of this pathogen. A vaccine against this organism would be ideal to prevent infection in high-risk populations such as the premature infant. S. aureus produces a wide variety of virulence factors that function to evade the natural host response to this pathogen, and previous vaccine attempts have been unsuccessful. The objective of this review is to discuss the potential for a vaccine against S. aureus and to examine past attempts at the prevention of neonatal staphylococcal disease.

The adjuvant AS03 is stockpiled for future formulations with new and existing vaccines for the control of pandemic influenza virus. We previously reported the immunogenicity of an A/H5N1 vaccine extemporaneously mixed with the AS03 adjuvant for 42 days following vaccination. This report extends those findings to 1 year after vaccination.

Therapeutics blocking the activity of tumor necrosis factor (anti-TNF) are a risk factor for invasive fungal infections; however, infectious risks to infants born to mothers receiving anti-TNF therapy are not well defined. We report a case of vertical transmission of disseminated histoplasmosis in a mother-infant pair exposed to anti-TNF therapy.

Background Current guidelines recommend vancomycin (VAN) dosing to achieve AUC/MIC ratio ≥400 for patients (pts) with serious MRSA bloodstream infections (BSI), but supporting data were largely derived in single center retrospective studies. A recent study using a Bayesian approach to estimate the VAN AUC found that patients with MRSA BSI who had an AUCDAY2/MICBMD ≥ 650 or an AUCDAY2/MICETEST ≥ 320 had lower incidences of failure (Clin Infect Dis 59:666, 2014). This study prospectively evaluated if these VAN AUCDAY2/MIC targets were associated with lower incidences of failure (PROVIDE, Award number UM1AI104681, Antibacterial Resistance Leadership Group). Methods Prospective, multi-center (n = 14), observational study (2014–2106) of hospitalized adults with confirmed MRSA BSI treated with VAN ≥ 72h. Exclusion: (1) neutropenia; (2) cystic fibrosis; (3) renal replacement therapy; (4) APACHE-II score > 25; (5) previous MRSA BSI within 60 days. VAN exposures were estimated using maximum a posteriori probability procedure in ADAPT 5. MICBMD and MICETEST were performed at a central laboratory. Outcomes: failure (30-day mortality or MRSA BSI ≥ 7 days); acute kidney injury (AKI), ≥1.5 × increase in serum creatinine (Scr) among patients with a baseline SCR < 2.0mg/dl. The study was powered at 80% to detect a 17.5% difference in failure between AUCDAY2/MIC groups. Results Among the 265 evaluable patients, mean (SD) age was 61 (17) and APACHE-II was 12 (6). Endocarditis was definite/possible in 29%. The MIC50/90 by BMD and ETEST were 1/1 and 1.5/1.5mg/l, respectively. Failure occurred in 18%; 26% had AKI. Mean (SD) VAN duration was 18 (14) days. Mean (SD) AUCDAY2 was 586.9 (235.5) and 44% and 73% of patients achieved an AUCDAY2/MICBMD ≥ 650 and AUCDAY2/MICETEST ≥ 320. In the multivariate analyses (Figure 1), failure was not significantly different between AUCDAY2/MIC groups. In contrast, AKI was significantly more common in patients with an AUCDAY2/ MICETEST > = 320. Conclusion Achievement of higher VAN AUCDAY2/MIC exposures for patients with MRSA BSIs were not associated with better outcomes and were found to result in increased AKI. Clinicians should assess the benefits vs. risks of using VAN regimens that confer high AUCDAY2/MIC exposures for patients with MRSA BSIs. Disclosures T. P. Lodise Jr., allergan: Consultant, Grant Investigator, Scientific Advisor and Speaker’s Bureau, Consulting fee and Speaker honorarium; medicines company: Consultant, Grant Investigator, Scientific Advisor and Speaker’s Bureau, Consulting fee, Research support and Speaker honorarium; melinta: Consultant, Consulting fee; motif: Consultant and Scientific Advisor, Consulting fee; paratek: Consultant and Scientific Advisor, Consulting fee; nabriva: Consultant, Consulting fee; M. J. Zervos, Merck, Inc.: Investigator, Research grant; M. Scheetz, Bayer: Scientific Advisor, Consulting fee; V. Fowler Jr., Pfizer, Novartis, Galderma, Novadigm, Durata, Debiopharm, Genentech, Achaogen, Affinium, Medicines Co., Cerexa, Tetraphase, Trius, MedImmune, Bayer, Theravance, Cubist, Basilea, Affinergy, Janssen, xBiotech, Contrafect: Consultant, Consulting fee; NIH, Basilea, MedImmune, Cerexa/Forest/Actavis/Allergan, Pfizer, Advanced Liquid Logics, Theravance, Novartis, Cubist/Merck; Medical Biosurfaces; Locus; Affinergy; Contrafect; Karius: Grant Investigator, Research grant; Green Cross, Cubist, Cerexa, Durata, Theravance; Debiopharm: Consultant, Consulting fee; UpToDate: author on several chapters, Royalties

OBJECTIVE: To compare the effectiveness of clindamycin, trimethoprim-sulfamethoxazole, and β-lactams for the treatment of pediatric skin and soft-tissue infections (SSTIs). METHODS: A retrospective cohort of children 0 to 17 years of age who were enrolled in Tennessee Medicaid, experienced an incident SSTI between 2004 and 2007, and received treatment with clindamycin (reference), trimethoprim-sulfamethoxazole, or a β-lactam was created. Outcomes included treatment failure and recurrence, defined as an SSTI within 14 days and between 15 and 365 days after the incident SSTI, respectively. Adjusted models stratified according to drainage status were used to estimate the risk of treatment failure and time to recurrence. RESULTS: Among the 6407 children who underwent drainage, there were 568 treatment failures (8.9%) and 994 recurrences (22.8%). The adjusted odds ratios for treatment failure were 1.92 (95% confidence interval [CI]: 1.49–2.47) for trimethoprim-sulfamethoxazole and 2.23 (95% CI: 1.71–2.90) for β-lactams. The adjusted hazard ratios for recurrence were 1.26 (95% CI: 1.06–1.49) for trimethoprim-sulfamethoxazole and 1.42 (95% CI: 1.19–1.69) for β-lactams. Among the 41 094 children without a drainage procedure, there were 2435 treatment failures (5.9%) and 5436 recurrences (18.2%). The adjusted odds ratios for treatment failure were 1.67 (95% CI: 1.44–1.95) for trimethoprim-sulfamethoxazole and 1.22 (95% CI: 1.06–1.41) for β-lactams; the adjusted hazard ratios for recurrence were 1.30 (95% CI: 1.18–1.44) for trimethoprim-sulfamethoxazole and 1.08 (95% CI: 0.99–1.18) for β-lactams. CONCLUSIONS: Compared with clindamycin, use of trimethoprim-sulfamethoxazole or β-lactams was associated with increased risks of treatment failure and recurrence. Associations were stronger for those with a drainage procedure.

Acute hematogenous osteomyelitis is a common disease that affects previously healthy children of all age groups. Despite its importance, there are limited data in the current literature to guide many aspects of the diagnosis and therapy of this infection. Over the last decade, our understanding of the etiology of this infection has changed, with increased recognition of Kingella kingae and the dramatic increase in community-associated Methicillin-resistant Staphylococcus aureus (CA-MRSA) infections. There is a need for the optimization of diagnostic strategies, such as MRI and serum inflammatory markers. Several recent studies have examined treatment strategies, including a rapid transition to oral antimicrobial therapy and a shortened overall course of therapy. Many new therapeutic options are on the horizon that will likely impact the management of this and other childhood bacterial infections. This review summarizes recent investigations into the optimal diagnosis and management of acute hematogenous osteomyelitis in children.

To define the molecular epidemiology of colonization and disease-associated isolates of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA).Laboratory-based comparative study of clinical staphylococcal isolates.We analyzed 255 pediatric CA-MRSA isolates for molecular characteristics associated with colonization and disease. We used polymerase chain reaction to determine the presence of Panton-Valentine Leukocidin and the lantibiotic element, bsaB, and to characterize the staphylococcal cassette chromosome mec type and accessory gene regulator locus. Pulsed-field gel electrophoresis was used to determine genetic relatedness between strains.A total of 150 isolates were obtained from patients with clinical disease (37 invasive infections, 113 noninvasive infections) and 105 from subjects with nasal colonization alone. Of 150 disease-associated isolates, 123 (82%) belonged to pulsed-field gel electrophoresis group USA300, whereas only 19 (18%) of 105 colonization isolates were of the USA300 lineage. Colonization isolates were less likely to possess staphylococcal cassette chromosome mec type IV, Panton-Valentine Leukocidin, or agr type 1 (P0.001).Colonization strains of CA-MRSA in children differ significantly from those strains recovered from patients with staphylococcal infections. This suggests that only colonization with specific strain types, rather than methicillin-resistant Staphylococcus aureus colonization in general, increases the risk for CA-MRSA disease.

We collected all Staphylococcus aureus isolates from the National Children's Hospital in Costa Rica to evaluate the prevalence and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA). Of 299 S. aureus isolates, 61% were MRSA. Most MRSA isolates (94.5%) carried SCCmec IV, and 45.6% carried Panton-Valentine leukocidin-encoding genes. The high prevalence of MRSA in this population highlights the need for improvement of antibiotic prescription and infection control measures.

Autosomal recessive interleukin-1 receptor-associated kinase (IRAK)-4 and myeloid differentiation factor (MyD)88 deficiencies impair Toll-like receptor (TLR)- and interleukin-1 receptor-mediated immunity. We documented the clinical features and outcome of 48 patients with IRAK-4 deficiency and 12 patients with MyD88 deficiency, from 37 kindreds in 15 countries.The clinical features of IRAK-4 and MyD88 deficiency were indistinguishable. There were no severe viral, parasitic, and fungal diseases, and the range of bacterial infections was narrow. Noninvasive bacterial infections occurred in 52 patients, with a high incidence of infections of the upper respiratory tract and the skin, mostly caused by Pseudomonas aeruginosa and Staphylococcus aureus, respectively. The leading threat was invasive pneumococcal disease, documented in 41 patients (68%) and causing 72 documented invasive infections (52.2%). P. aeruginosa and Staph. aureus documented invasive infections also occurred (16.7% and 16%, respectively, in 13 and 13 patients, respectively). Systemic signs of inflammation were usually weak or delayed. The first invasive infection occurred before the age of 2 years in 53 (88.3%) and in the neonatal period in 19 (32.7%) patients. Multiple or recurrent invasive infections were observed in most survivors (n = 36/50, 72%).Clinical outcome was poor, with 24 deaths, in 10 cases during the first invasive episode and in 16 cases of invasive pneumococcal disease. However, no death and invasive infectious disease were reported in patients after the age of 8 years and 14 years, respectively. Antibiotic prophylaxis (n = 34), antipneumococcal vaccination (n = 31), and/or IgG infusion (n = 19), when instituted, had a beneficial impact on patients until the teenage years, with no seemingly detectable impact thereafter.IRAK-4 and MyD88 deficiencies predispose patients to recurrent life-threatening bacterial diseases, such as invasive pneumococcal disease in particular, in infancy and early childhood, with weak signs of inflammation. Patients and families should be informed of the risk of developing life-threatening infections; empiric antibacterial treatment and immediate medical consultation are strongly recommended in cases of suspected infection or moderate fever. Prophylactic measures in childhood are beneficial, until spontaneous improvement occurs in adolescence.

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.

Skin and skin-structure infections are common in ambulatory settings. However, the efficacy of various antibiotic regimens in the era of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) is unclear.We enrolled outpatients with uncomplicated skin infections who had cellulitis, abscesses larger than 5 cm in diameter (smaller for younger children), or both. Patients were enrolled at four study sites. All abscesses underwent incision and drainage. Patients were randomly assigned in a 1:1 ratio to receive either clindamycin or trimethoprim-sulfamethoxazole (TMP-SMX) for 10 days. Patients and investigators were unaware of the treatment assignments and microbiologic test results. The primary outcome was clinical cure 7 to 10 days after the end of treatment.A total of 524 patients were enrolled (264 in the clindamycin group and 260 in the TMP-SMX group), including 155 children (29.6%). One hundred sixty patients (30.5%) had an abscess, 280 (53.4%) had cellulitis, and 82 (15.6%) had mixed infection, defined as at least one abscess lesion and one cellulitis lesion. S. aureus was isolated from the lesions of 217 patients (41.4%); the isolates in 167 (77.0%) of these patients were MRSA. The proportion of patients cured was similar in the two treatment groups in the intention-to-treat population (80.3% in the clindamycin group and 77.7% in the TMP-SMX group; difference, -2.6 percentage points; 95% confidence interval [CI], -10.2 to 4.9; P=0.52) and in the populations of patients who could be evaluated (466 patients; 89.5% in the clindamycin group and 88.2% in the TMP-SMX group; difference, -1.2 percentage points; 95% CI, -7.6 to 5.1; P=0.77). Cure rates did not differ significantly between the two treatments in the subgroups of children, adults, and patients with abscess versus cellulitis. The proportion of patients with adverse events was similar in the two groups.We found no significant difference between clindamycin and TMP-SMX, with respect to either efficacy or side-effect profile, for the treatment of uncomplicated skin infections, including both cellulitis and abscesses. (Funded by the National Institute of Allergy and Infectious Diseases and the National Center for Advancing Translational Sciences, National Institutes of Health; ClinicalTrials.gov number, NCT00730028.).

Influenza A(H5N1) vaccination strategies that improve the speed of the immunological response and cross-clade protection are desired. We compared the immunogenicity of a single 15-μg or 90-μg dose of A/H5N1/Indonesia/05/05 (clade 2) vaccine in adults who were previously primed with A/H5N1/Vietnam/1203/2004 (clade 1) vaccine. High-dose vaccine resulted in significantly higher titers to both clade 1 and 2 antigens. Clade 2 titers were unaffected by the previous dose of clade 1 vaccine. Low-dose priming with a mismatched pandemic influenza A(H5N1) vaccine would improve the rapidity, magnitude, and cross-reactivity of the immunological response following a single high-dose, unadjuvanted, pandemic vaccine.

Adjuvants enhance immunity elicited by vaccines through mechanisms that are poorly understood. Using a systems biology approach, we investigated temporal protein expression changes in five primary human immune cell populations: neutrophils, monocytes, natural killer cells, T cells, and B cells after administration of either an Adjuvant System 03 adjuvanted or unadjuvanted split-virus H5N1 influenza vaccine. Monocytes demonstrated the strongest differential signal between vaccine groups. On day 3 post-vaccination, several antigen presentation-related pathways, including MHC class I-mediated antigen processing and presentation, were enriched in monocytes and neutrophils and expression of HLA class I proteins was increased in the Adjuvant System 03 group. We identified several protein families whose proteomic responses predicted seroprotective antibody responses (>1:40 hemagglutination inhibition titer), including inflammation and oxidative stress proteins at day 1 as well as immunoproteasome subunit (PSME1 and PSME2) and HLA class I proteins at day 3 in monocytes. While comparison between temporal proteomic and transcriptomic results showed little overlap overall, enrichment of the MHC class I antigen processing and presentation pathway in monocytes and neutrophils was confirmed by both approaches.

BACKGROUNDVaccine development for influenza A/H5N1 is an important public health priority, but H5N1 vaccines are less immunogenic than seasonal influenza vaccines. Adjuvant System 03 (AS03) markedly enhances immune responses to H5N1 vaccine antigens, but the underlying molecular mechanisms are incompletely understood.OBJECTIVE AND METHODSWe compared the safety (primary endpoint), immunogenicity (secondary), gene expression (tertiary) and cytokine responses (exploratory) between AS03-adjuvanted and unadjuvanted inactivated split-virus H5N1 influenza vaccines. In a double-blinded clinical trial, we randomized twenty adults aged 18-49 to receive two doses of either AS03-adjuvanted (n = 10) or unadjuvanted (n = 10) H5N1 vaccine 28 days apart. We used a systems biology approach to characterize and correlate changes in serum cytokines, antibody titers, and gene expression levels in six immune cell types at 1, 3, 7, and 28 days after the first vaccination.RESULTSBoth vaccines were well-tolerated. Nine of 10 subjects in the adjuvanted group and 0/10 in the unadjuvanted group exhibited seroprotection (hemagglutination inhibition antibody titer > 1:40) at day 56. Within 24 hours of AS03-adjuvanted vaccination, increased serum levels of IL-6 and IP-10 were noted. Interferon signaling and antigen processing and presentation-related gene responses were induced in dendritic cells, monocytes, and neutrophils. Upregulation of MHC class II antigen presentation-related genes was seen in neutrophils. Three days after AS03-adjuvanted vaccine, upregulation of genes involved in cell cycle and division was detected in NK cells and correlated with serum levels of IP-10. Early upregulation of interferon signaling-related genes was also found to predict seroprotection 56 days after first vaccination.CONCLUSIONSUsing this cell-based systems approach, novel mechanisms of action for AS03-adjuvanted pandemic influenza vaccination were observed.TRIAL REGISTRATIONClinicalTrials.gov NCT01573312.

Clostridium difficile, a common cause of antibiotic-associated diarrhea, has been reported to recur in high rates in adults. The rates and risk factors for recurrent C difficile infection (rCDI) in children have not been well established.We conducted a retrospective cohort study of 186 pediatric patients seen at a tertiary care referral center for a 5-year period diagnosed as having a primary C difficile infection. Children with recurrent disease, defined as return of symptoms of C difficile infection and positive testing ≤60 days after the completion of therapy, were compared with children who did not experience an episode of recurrence.Of the 186 pediatric patients included in this study, 41 (22%) experienced rCDI. On univariable analysis, factors significantly associated with rCDI included malignancy, recent hospitalization, recent surgery, antibiotic use, number of antibiotic exposures by class, acid blocker use, immunosuppressant use, and hospital-acquired disease. On multivariable analysis, malignancy (odds ratio [OR] 3.39, 95% confidence interval [CI] 1.52-7.85), recent surgery (OR 2.40, 95% CI 1.05-5.52), and the number of antibiotic exposures by class (OR 1.33, 95% CI 1.01-1.75) were significantly associated with recurrent disease in children.The rate of rCDI in children was 22%. Recurrence was significantly associated with the risk factors of malignancy, recent surgery, and the number of antibiotic exposures by class.

Despite the importance of Staphylococcus aureus as a common invasive bacterial pathogen, the humoral response to infection remains inadequately defined, particularly in children. The purpose of this study was to assess the humoral response to extracellular staphylococcal virulence factors, including the bicomponent leukotoxins, which are critical for the cytotoxicity of S. aureus toward human neutrophils. Children with culture-proven S. aureus infection were prospectively enrolled and stratified by disease type. Fifty-three children were enrolled in the study, of which 90% had invasive disease. Serum samples were obtained during the acute (within 48 h) and convalescent (4 to 6 weeks postinfection) phases, at which point both IgG titers against S. aureus exotoxins were determined, and the functionality of the generated antibodies was evaluated. Molecular characterization of clinical isolates was also performed. We observed a marked rise in antibody titer from acute-phase to convalescent-phase sera for LukAB, the most recently described S. aureus bicomponent leukotoxin. LukAB production by the isolates was strongly correlated with cytotoxicity in vitro , and sera containing anti-LukAB antibodies potently neutralized cytotoxicity. Antibodies to S. aureus antigens were detectable in healthy pediatric controls but at much lower titers than in sera from infected subjects. The discovery of a high-titer, neutralizing antibody response to LukAB during invasive infections suggests that this toxin is produced in vivo and that it elicits a functional humoral response.

Influenza pandemics have occurred 4 times during the past 100 years, repeatedly demonstrating an ability to cause excess mortality, morbidity, and varying degrees of social and economic disruption. The threat of a new pandemic persists as novel avian influenza A strains continue to emerge with the ability to induce high mortality (but, to date, limited transmissibility) in humans. These antigenically distinct influenza viruses are categorized, based on phylogenetic characterization and sequence homology of the hemagglutinin (HA) gene, into clades. In the United States, a key component of pandemic preparedness is the National Prepandemic Influenza Vaccine Stockpile [1], which currently contains 4 H5N1 avian influenza strain vaccines (clade 1, A/Vietnam/1203/2004; clade 2.1.3, A/Indonesia/05/2005; clade 2.2, A/bar-headed goose/Qinghai/1A/2005; and clade 2.3.4, A/Anhui/1/2005). The rationale behind the stockpile is that a vaccine made from pre-pandemic subtype virus would provide partial cross-protection through immunologic priming [2], thereby benefiting first responders and other high-risk or priority groups before a better-matched vaccine against the pandemic strain becomes available. Because vaccines comprising H5N1 and other avian pandemic strains have had poor immunogenicity in unprimed populations [3, 4], 2 immune-enhancing adjuvants have been included in the stockpile (AS03 and MF59). The AS03 adjuvant is a proprietary oil-in-water emulsion product, manufactured by GlaxoSmithKline, which has been in advanced clinical development for use with a number of seasonal, 2009 pandemic A(H1N1), and pandemic-potential avian influenza (eg, H5N1 and H7N9) virus vaccines. Nonetheless, the optimal strategy for use of pandemic vaccine with adjuvants is incompletely elucidated. Given the urgent time frame for vaccine development once an influenza pandemic is declared, it is likely that several manufacturers would be tasked to produce both vaccines and adjuvants sufficient to protect the global population. Maximum flexibility could be realized by pairing vaccines and adjuvants postmanufacture. To assess the feasibility of this approach, we evaluated the safety and immunogenicity of an inactivated influenza A(H5N1) virus vaccine administered alone or in combination with AS03 adjuvant, formulated at the point of care.

The pursuit of an effective staphylococcal vaccine has never been more critical, as community-associated MRSA has become the most common bacterial infection in the US. In this commentary, we will highlight new discoveries in the host response to colonization and infection with S. aureus, discuss potential antigens that might be used as vaccines, and make recommendations as to how the field can move forward towards discovering the "holy grail" of an effective staphylococcal vaccine.

Methicillin-resistant Staphylococcus aureus (MRSA) isolates with vancomycin minimal inhibitory concentrations (MIC's) ≥ 1.5 μg/mL have been associated with poorer clinical outcomes and treatment failures in adults. We evaluated vancomycin MIC's in 71 invasive pediatric community-acquired MRSA (CA-MRSA) isolates from 2004-2008 using the E-test micro-method and the E-test macro-method. The modal MIC by micro-method was 1.5 μg/mL, and median vancomycin MIC's did not increase over time.

Outbreaks of invasive methicillin-resistant Staphylococcus aureus infection within families are unusual. We investigated 2 family clusters of invasive methicillin-resistant Staphylococcus aureus infection, including 1 in which a young mother died of fulminant pneumonia. Although surveillance via culture of family contacts of patients with invasive methicillin-resistant Staphylococcus aureus infection is not currently recommended, such clusters should stimulate reevaluation of preventive measures.

time, ∼30% of all persons are colonized with S. aureus, with the anterior nares serving as its critical niche [3]. Although colonization typically precedes infection, relatively few colonized individuals develop staphylococcal infections. There are, undoubtedly, a variety of host-organism interactions that play a role in this symbiosis; yet, much of what is known has been derived from the study of persons with clinical disease, not those in

Objective The characteristics of staphylococcal skin and soft tissue infections (SSTIs) are poorly understood in northern South America and the Caribbean. The objectives of this study were to determine the frequency of methicillin resistance among Staphylococcus aureus isolates in an emergency department (ED) in Guyana and to identify specific molecular characteristics of these methicillin-resistant Staphylococcus aureus (MRSA) strains. Methods This was a cross-sectional study conducted at the main teaching hospital in Georgetown, Guyana. Eligible subjects included patients of all ages with SSTIs with obtainable purulent material. Purulent material was cultured, and S. aureus isolates were evaluated for antibiotic susceptibilities by disc diffusion. Molecular characterisation of MRSA isolates included identification of SCC mec type, assignment of genetic relatedness by rep-PCR and determination of the presence of two exotoxins, Panton-Valentine Leukocidin (PVL) and LukAB. Results Eighty-five samples were collected; of these, 47 grew S. aureus. 24 of the 47 S. aureus samples were MRSA (51%; 95% CI 37% to 65%), representing 28% of all samples. All MRSA isolates were SCC mec type IV, PVL positive, LukAB positive and were highly related to the current epidemic clone in the USA, USA300. Conclusions Here, we demonstrate a clinically significant proportion of methicillin resistance in SSTI-associated staphylococcal isolates. Guyanese isolates were highly related to the most common community-associated strain seen in the USA, USA300. These results have important implications for empiric antibiotic therapy and infection control policies in Guyana and similar settings.

Background Modified vaccinia Ankara (MVA) is being developed as a safer smallpox vaccine and is being placed in the US Strategic National Stockpile (SNS) as a liquid formulation for subcutaneous (SC) administration at a dose of 1 × 10 8 TCID 50 in a volume of 0.5 mL. This study compared the safety and immunogenicity of the standard formulation, dose and route with both a more stable, lyophilized formulation and with an antigen-sparing intradermal (ID) route of administration. Methods 524 subjects were randomized to receive either a full dose of Lyophilized-SC, a full dose of Liquid-SC or 20% (2 × 10 7 TCID 50 in 0.1 mL) of a full dose Liquid-ID MVA on Days 0 and 28. Safety and immunogenicity were followed through 180 days post second vaccination. Results Among the 3 groups, the proportion of subjects with moderate/severe functional local reactions was significantly different ( P = 0.0013) between the Lyophilized-SC group (30.3%), the Liquid-SC group (13.8%) and Liquid-ID group (22.0%) only after first vaccination; and for moderate/severe measured erythema and/or induration after any vaccination ( P = 0.0001) between the Lyophilized-SC group (58.2%), the Liquid-SC group (58.1%) and the Liquid-ID group (94.8%) and the reactions lasted longer in the Liquid-ID group. In the ID Group, 36.1% of subjects had mild injection site skin discoloration lasting ≥6 months. After second vaccination Day (42–208), geometric mean of peak neutralization titers were 87.8, 49.5 and 59.5 for the Lyophilized-SC, Liquid-SC and Liquid-ID groups, respectively, and the maximum number of responders based on peak titer in each group was 142/145 (97.9%), 142/149 (95.3%) and 138/146 (94.5%), respectively. At 180 days after the second vaccination, geometric mean neutralization titers declined to 11.7, 10.2 and 10.4 with only 54.3%, 39.2% and 35.2% of subjects remaining seropositive for the Lyophilized-SC, Liquid-SC and Liquid-ID groups, respectively. Both the Lyophilized-SC and Liquid-ID groups were considered non-inferior (primary objective) to the Liquid-SC group. Conclusions Transitioning to a lyophilized formulation, which has a longer shelf life, will not negatively impact immunogenicity. In a situation where insufficient vaccine is available, ID vaccination could be used, increasing the number of available doses of vaccine in the SNS 5-fold (i.e., from 20 million to 100 million doses).

OBJECTIVE: The study aimed to assess whether maternal colonization with Staphylococcus aureus during pregnancy or at delivery was associated with infant staphylococcal colonization. METHODS: For this prospective cohort study, women were enrolled at 34 to 37 weeks of gestation between 2007 and 2009. Nasal and vaginal swabs for culture were obtained at enrollment; nasal swabs were obtained from women and their infants at delivery and 2- and 4-month postbirth visits. Logistic regression was used to determine whether maternal colonization affected infant colonization. RESULTS: Overall, 476 and 471 mother-infant dyads had complete data for analysis at enrollment and delivery, respectively. Maternal methicillin-resistant S aureus (MRSA) colonization occurred in 10% to 17% of mothers, with the highest prevalence at enrollment. Infant MRSA colonization peaked at 2 months of age, with 20.9% of infants colonized. Maternal staphylococcal colonization at enrollment increased the odds of infant staphylococcal colonization at birth (odds ratio; 95% confidence interval: 4.8; 2.4–9.5), hospital discharge (2.6; 1.3–5.0), at 2 months of life (2.7; 1.6–4.3), and at 4 months of life (2.0; 1.1–3.5). Similar results were observed for maternal staphylococcal colonization at delivery. Fifty maternal-infant dyads had concurrent MRSA colonization: 76% shared isolates of the same pulsed-field type, and 30% shared USA300 isolates. Only 2 infants developed staphylococcal disease. CONCLUSIONS: S aureus colonization (including MRSA) was extremely common in this cohort of maternal-infant pairs. Infants born to mothers with staphylococcal colonization were more likely to be colonized, and early postnatal acquisition appeared to be the primary mechanism. * Abbreviations: CA-MRSA — : community-associated methicillin-resistant Staphylococcus aureus GBS — : group B Streptococcus GEE — : generalized estimating equation MRSA — : methicillin-resistant Staphylococcus aureus MSSA — : methicillin-susceptible Staphylococcus aureus PCR — : polymerase chain reaction PVL — : Panton-Valentine leukocidin SSTIs — : skin and soft-tissue infections VUMC — : Vanderbilt University Medical Center

Staphylococcus aureus infections are associated with diverse clinical manifestations leading to significant morbidity and mortality. To define the role of the host response in the clinical manifestations of the disease, we characterized whole blood transcriptional profiles of children hospitalized with community-acquired S. aureus infection and phenotyped the bacterial strains isolated. The overall transcriptional response to S. aureus infection was characterized by over-expression of innate immunity and hematopoiesis related genes and under-expression of genes related to adaptive immunity. We assessed individual profiles using modular fingerprints combined with the molecular distance to health (MDTH), a numerical score of transcriptional perturbation as compared to healthy controls. We observed significant heterogeneity in the host signatures and MDTH, as they were influenced by the type of clinical presentation, the extent of bacterial dissemination, and time of blood sampling in the course of the infection, but not by the bacterial isolate. System analysis approaches provide a new understanding of disease pathogenesis and the relation/interaction between host response and clinical disease manifestations.

Background. Two doses of either trivalent live attenuated or inactivated influenza vaccines (LAIV and TIV, respectively) are approved for young children ($24 months old for LAIV and $6 months old for TIV) and induce protective antibody responses. However, whether combinations of LAIV and TIV are safe and equally immunogenic is unknown. Furthermore, LAIV is more protective than TIV in children for unclear reasons. Methods. Children 6‐35 months old were administered, 1 month apart, 2 doses of either TIV or LAIV, or combinations of LAIV and TIV in both prime/boost sequences. Influenza-specific antibodies were measured by hemagglutination inhibition (HAI), and T cells were studied in flow cytometric and functional assays. Highly conserved M1, M2, and NP peptides predicted to be presented by common HLA class I and II were used to stimulate interferon-c enzyme-linked immunospot responses. Results. All LAIV and/or TIV combinations were well tolerated and induced similar HAI responses. In contrast, only regimens containing LAIV induced influenza-specific CD4 1 , CD8 1 , and cdT cells, including T cells specific for highly conserved influenza peptides. Conclusions. Prime/boost combinations of LAIV and TIV in young children were safe and induced similar protective antibodies. Only LAIV induced CD4 1 ,C D8 1 ,a ndcd T cells relevant for broadly protective heterosubtypic immunity.

Objective To determine the frequency and clinical importance of methicillin-resistant Staphylococcus aureus (MRSA) colonization in student athletes. Design Prospective observational cohort study. Setting A major university in the southeastern United States. Participants Student athletes participating in the men's football and women's lacrosse programs (N = 126). Main Exposure Monthly assessment of S aureus nasal colonization. Main Outcome Measures Trends in S aureus colonization over time and the occurrence of skin and soft tissue infections. Results Methicillin-resistant S aureus nasal colonization varied significantly through the athletic season (4%-23%), peaking during times of highest athletic activity. This increase in colonization was not associated with the development of an outbreak of skin and soft tissue infections, and no single MRSA clone emerged as a dominant isolate. Conclusions During the athletic season, there is a considerable burden of MRSA colonization in student athletes; however, colonization alone appears to be insufficient to trigger an outbreak of staphylococcal infections. A combination of distinct molecular characteristics in the organism and specific host factors may govern the development of staphylococcal disease.

Resistance to chlorhexidine gluconate (CHG) and quaternary ammonium compounds (QACs) is a potential public health threat, given widespread use of these agents for routine hospital cleaning, skin antisepsis, and patient decolonization.1–3 Development of tolerance to CHG and QACs among methicillin-resistant Staphylococcus aureus (MRSA) isolates can be mediated by energy-dependent multidrug efflux proteins, which show increased expression in response to selective pressure from disinfectant use.4 Plasmid-encoded efflux pump genes qac A/B and smr confer tolerance to both CHG and QACs, along with other compounds, including intercalating dyes and cationic biocides.5,6 The efflux pump genes qac A/B and smr have been found in MRSA isolates with varying frequencies globally, mostly in tertiary-care adult and pediatric populations.6 Here we describe an evaluation of pediatric clinical MRSA isolates for the presence of disinfectant resistance genes qac A/B and smr, and for tolerance to CHG. Two hundred eighty-one clinical pediatric MRSA isolates from 2004 through 2009 were selected randomly from the Vanderbilt Children’s Hospital MRSA Repository, a de-identified collection of unique MRSA isolates obtained from emergency room or hospitalized general pediatric patients with MRSA infection. The MRSA Repository is approved by the Vanderbilt Institutional Review Board and maintained as a de-identified dataset with limited clinical information. All isolates were identified by the Vanderbilt University Hospital Laboratory according to Clinical and Laboratory Standards Institute standards prior to repository transfer. Isolates were cultured overnight on blood agar at 37°C, and purified genomic DNA was used as a template for repetitive-element, sequence-based polymerase chain reaction to determine genetic classification of strains (DiversiLab System, Biomerieux). Plasmid-encoded qac A/B and smr genes were evaluated by PCR using previously published primers.7,8 Minimum bactericidal concentrations (MBCs) of a randomly selected subset of 5 qac A/B and 5 smr positive MRSA strains, along with 5 randomly selected negative controls, were determined by broth microdilution methods using 20% w/v chlorhexidine digluconate solution (Sigma-Aldrich Corp., St. Louis, Mo.).1 A Fisher Exact Test was performed to determine statistical significance. Of the 281 isolates identified in the repository, 201 isolates (71.5%) belonged to USA300, the current epidemic clone in the United States. Of the remainder, 31 isolates (11.0%) belonged to USA100, 31 isolates (11.0%) belonged to USA500, and 18 isolates (6.4%) were other pulse types. Genes for qac A/B or smr were detected in 18.5% of isolates (52/281); 13.9% contained smr only, 4.3% harbored qac A/B, and 1 isolate contained both smr and qacA/B. Non-USA300 MRSA isolates were significantly more likely to harbor qac A/B or smr genes than USA300 MRSA isolates (Figure 1; P = 0.0175). MBC testing of 15 MRSA isolates (5 negative controls, 5 qac A/B positive, and 5 smr positive) in serial dilutions of CHG showed that all 15 isolates had MBCs less than 16 μg/mL, well below the recommended in-use concentration of 2000 μg/mL.6 No significant differences in MBC were noted between qac A/B or smr positive isolates and negative controls. Figure 1 Presence of disinfectant resistance genes smr and qac A/B by methicillin-resistant Staphylococcus aureus pulse type. Non-USA300 isolates were more likely than USA300 isolates to harbor smr or qacA/B (P = 0.0175). We found a moderate prevalence of plasmid-encoded disinfectant resistance genes (18.5%) in this random sample of pediatric MRSA isolates, similar to other studies in US pediatric populations.9 In our study, pediatric isolates belonging to USA300, the pulse type associated with the community-associated MRSA epidemic, were less likely than non-USA300 MRSA isolates to possess disinfectant resistance genes. Nearly 15% of the USA300 strains, however, also harbored genes for efflux pumps capable of conferring tolerance to CHG. This was an unexpected finding given the USA300 clone’s predominant association with community-onset MRSA infection, since CHG is considered a healthcare-associated exposure. This study has limited generalizability because it represents a single center study that may not apply to other geographic regions. The de-identified nature of the dataset attached to the MRSA repository did not allow for evaluation of the emergence of disinfectant resistance genes over time, or evaluation of the relationship of disinfectant resistance genes to specific MRSA infections, such as device-associated infection. CHG has gained an increasing role in the infection prevention arsenal for reducing healthcare-associated infections, and CHG resistance threatens current infection prevention efforts directed against multi-drug resistant organisms. CHG is widely used for surgical antisepsis, and daily bathing of critically-ill patients with CHG is commonplace. The Randomized Evaluation of Decolonization vs Universal Clearance to Eliminate (REDUCE) MRSA trial showed that universal decolonization using nasal mupirocin and bathing with CHG significantly reduced rates of bloodstream infections in the community intensive care unit setting.3 The popularity of universal decolonization strategies will further increase the use of CHG in hospital settings. Thus, it is important to consider the mechanisms by which MRSA might survive CHG exposure in the clinical setting. Staphylococcus aureus possesses both chromosomal and plasmid-mediated efflux pumps capable of targeting a wide range of compounds, from antimicrobials to disinfectants. Previous evaluations of CHG bactericidal activity against qac A/B gene-positive MRSA strains have shown evidence of increased tolerance to CHG with elevated MBC in those strains.1, 6 Another study showed increased tolerance and overexpression of S. aureus efflux pumps in association with exposure to disinfectants.4 Our limited evaluation of bactericidal activity showed no evidence of increased MBC in qac A/B or smr positive isolates. Reassuringly, no MRSA isolates harboring phenotypic CHG resistance have been reported to date. In summary, this report demonstrates a moderate prevalence of disinfectant resistance genes in a pediatric population, both in USA300 and non-USA300 MRSA isolates. Non-USA300 isolates were significantly more likely to harbor disinfectant resistance genes. Ongoing evaluation of genotypic and phenotypic CHG resistance will help gauge the effectiveness of future infection prevention efforts utilizing CHG.

We describe a child with very late-onset group B Streptococcus sepsis and meningitis, systemic shigellosis, and chronic osteomyelitis. Peripheral blood cells obtained from the patient and her brother did not respond to stimulation with either interleukin-1beta or lipopolysaccharide. Sequencing of the interleukin-1 receptor-associated kinase-4 gene revealed 2 novel mutations.

The rate of vancomycin failure in patients with hospital-acquired pneumonia (HAP) caused by methicillin-resistant Staphylococcus aureus (MRSA) has exceeded 40% in several studies. This observation was attributed initially to the lack of weight-based dosing and targeting of lower trough concentrations. However, a subsequent study demonstrated no additional benefit in patients who achieved trough vancomycin concentrations15 mg/L compared with patients with concentrations between 5 and 15 mg/L. We sought to identify contributors to vancomycin failure in patients with MRSA HAP.This was a retrospective study of patients in a surgical intensive care unit with MRSA HAP who received vancomycin between January 1, 2005, and July 31, 2007. Clinical outcomes, microbiological data, prior antibiotic exposure, ventilator days, co-morbidities, and demographics were compared in patients with clinical success and those with treatment failure. Their characteristics were compared using a two-sided Fisher exact test or Mann-Whitney U test, as appropriate for nominal or continuous data.More patients in the treatment failure group had received one or more doses of vancomycin within 90 days leading up to MRSA HAP (84% vs. 47%; p = 0.04). In addition, the duration of prior vancomycin exposure was significantly longer among patients in the treatment failure group (6 vs. 0 days; p0.05). There were no statistically significant differences in the percentages of patients who achieved a vancomycin trough concentrationsor =15 mg/dL within the first 48 h (28% vs. 17%; p = 0.69), 72 h (44% vs. 39%; p = 1.0), or 96 h (56% vs. 44%; p = 0.74) after starting treatment. Patients in the failure group had a significantly higher overall mortality rate (32% vs. 0; p = 0.02).These data suggest that patients who have recent exposure to vancomycin are at high risk for vancomycin failure and may benefit from an appropriate alternative when a diagnosis of MRSA HAP is made.

Clinical samples from 250 pregnant women undergoing screening for rectovaginal group B streptococcus colonization were evaluated concurrently for the presence of methicillin-resistant Staphylococcus aureus (MRSA). Overall, S aureus was detected in 21.6% of the women; 53.7% of the isolates were MRSA. Despite a lack of risk factors for MRSA colonization, rectovaginal MRSA was detected in 10.4% of pregnant women in this study.

PURPOSE OF REVIEW Staphylococcus aureus is an important pathogen, contributing to both pediatric and adult infections in the USA. In recent years, methicillin-resistant Staphylococcus aureus (MRSA) has become a source of public fear and outcry. In this article, we review facts and fiction of sinonasal MRSA. RECENT FINDINGS Although the exact role of bacteria in chronic rhinosinusitis continues to be debated, the role of MRSA in these patients is even less apparent. When MRSA is involved, there are few to guide treatment. Oral, parenteral, and topical antibiotics are all used in the treatment of sinonasal MRSA. MRSA eradication has been advocated by some; however, there are few data to support the efficacy of eradication. Current treatment regimens by the authors are reviewed. SUMMARY There is much that is not known about the role of MRSA in sinonasal infection, and the impact of sinonasal MRSA on the health quality of the community also remains undefined. Treatment outlines are presented; however, with the current state of data, these treatment preferences lack a solid, evidence-based foundation that is favored. Future studies will lay the foundation for more rigorously supported treatment algorithms.

There are currently no clear consensus recommendations for the treatment and prevention of community-associated methicillin-resistant Staphylococcus aureus skin and soft tissue infections in pediatric patients. We surveyed over 100 Pediatric Infectious Diseases consultants and found considerable variability in both the treatment of skin and soft tissue infections and the strategies used for the management of children with recurrent MRSA disease.

Acute irritant contact dermatitis induced by cutaneous exposure to chemicals is a common dermatologic problem in the workplace. In severe cases, irritant contact responses can result in a caustic burn. Chemical burn induced by concentrated sodium hypochlorite (the active ingredient in bleach) has been reported infrequently in the literature, with no previously reported cases of chemical burn due to an alkyl sulfate (a common surfactant in cleaning fluids). Here we describe a chemical burn in a 16-year-old girl resulting from exposure to a solution of concentrated sodium hypochlorite and alkyl sulfate applied as a sanitizer to the interior of roller skates worn at work.The diagnosis was made on the basis of the patient's exposure history, clinical appearance, and laboratory results. On physical examination, the erythematous plaque, located at the site of chemical exposure, had intact skin lines, surrounding edema, and decreased sensitivity to touch. The peripheral white blood cell count was within normal limits and bacterial and fungal cultures from the lesion were negative.The irritant effect of exposure to chemicals, including those that usually are not major irritants, and the possible additive effect of simultaneous exposure to different chemicals, should be considered in the differential diagnosis of acute dermatitis of unknown etiology. Moreover, increased reporting of cases of chemical-induced acute irritant contact dermatitis will help lead to crucial early and appropriate treatment.