Epidemiology of invasive pneumococcal disease in southern California: implications for the design and conduct of a pneumococcal conjugate vaccine efficacy trial

Effect of Haemophilus influenzae Type b and 13-Valent Pneumococcal Conjugate Vaccines on Childhood Pneumonia Hospitalizations and Deaths in Botswana

BACKGROUND

Globally, pneumonia is the leading cause of death among children. Few data exist regarding the effect of Haemophilus influenzae type b (Hib) vaccine and 13-valent pneumococcal conjugate vaccine (PCV-13) on the burden of childhood pneumonia in African settings.

METHODS

We collected data on children aged 1 to 59 months at 3 hospitals in Botswana. Hib vaccine and PCV-13 were introduced in Botswana in November 2010 and July 2012, respectively. We compared pneumonia hospitalizations and deaths prevaccine (January 2009 to October 2010) with postvaccine (January 2013 to December 2017) using seasonally adjusted, interrupted time-series analyses.

RESULTS

We identified 6943 pneumonia hospitalizations and 201 pneumonia deaths. In the prevaccine period, pneumonia hospitalizations and deaths increased by 24% (rate, 1.24; 95% CI, .94-1.64) and 59% (rate, 1.59; 95% CI, .87-2.90) per year, respectively. Vaccine introduction was associated with a 48% (95% CI, 29-62%) decrease in the number of pneumonia hospitalizations and a 50% (95% CI, 1-75%) decrease in the number of pneumonia deaths between the end of the prevaccine period (October 2010) and the beginning of the postvaccine period (January 2013). During the postvaccine period, pneumonia hospitalizations and deaths declined by 6% (rate, .94; 95% CI, .89-.99) and 22% (rate, .78; 95% CI, .67-.92) per year, respectively.

CONCLUSIONS

Pneumonia hospitalizations and deaths among children declined sharply following introduction of Hib vaccine and PCV-13 in Botswana. This effect was sustained for more than 5 years after vaccine introduction, supporting the long-term effectiveness of these vaccines in preventing childhood pneumonia in Botswana.

Review on Pneumococcal Infection in Children

Childhood pneumococcal infection is a growing concern among paediatricians especially, in countries where there is no routine vaccination program against Streptococcal pneumoniae. The disease is associated with significant morbidity and mortality in young children particularly those who are under the age of two years. Its main virulent factors include polysaccharide capsule, autolysin, pneumolysin, choline-binding Protein A, the higher chance for genetic transformation, and the presence of pilli that facilitate enhanced binding of bacteria to host cellular surfaces. More severe and invasive pneumococcal infections are seen in children with immunodeficiencies, hypofunctional spleen, malnutrition, chronic lung disease and nephrotic syndrome. The disease spectrum includes a range of manifestations from trivial upper respiratory tract infections to severe invasive pneumococcal disease (PD). The basis of diagnosis is the isolation of bacteria in the culture of body fluids including blood. Antibiotics are best guided by sensitivity patterns and the emergence of resistance is a growing concern.

Total Synthesis of the Lipid-Anchor-Attached Core Trisaccharides of Lipoteichoic Acids of Streptococcus pneumoniae and Streptococcus oralis Uo5

Herein we report an efficient total synthesis of lipid-anchor-appended core trisaccharides of lipoteichoic acids of Streptococcus pneumoniae and Streptococcus oralis Uo5. The key features include the expedient synthesis of the rare sugar 2,4,6-trideoxy-2-acetamido-4-amino-d-Galp building block via one-pot sequential S_N2 reactions and the α-selective coupling of d-thioglucoside with the diacyl glycerol acceptor to construct a common disaccharide acceptor, which was utilized in the total synthesis of target molecules 1 and 2.

Carriage Dynamics of Pneumococcal Serotypes in Naturally Colonized Infants in a Rural African Setting During the First Year of Life

Streptococcus pneumoniae (the pneumococcus) carriage precedes invasive disease and influences population-wide strain dynamics, but limited data exist on temporal carriage patterns of serotypes due to the prohibitive costs of longitudinal studies. Here, we report carriage prevalence, clearance and acquisition rates of pneumococcal serotypes sampled from newborn infants bi-weekly from weeks 1 to 27, and then bi-monthly from weeks 35 to 52 in the Gambia. We used sweep latex agglutination and whole genome sequencing to serotype the isolates. We show rapid pneumococcal acquisition with nearly 31% of the infants colonized by the end of first week after birth and quickly exceeding 95% after 2 months. Co-colonization with multiple serotypes was consistently observed in over 40% of the infants at each sampling point during the first year of life. Overall, the mean acquisition time and carriage duration regardless of serotype was 38 and 24 days, respectively, but varied considerably between serotypes comparable to observations from other regions. Our data will inform disease prevention and control measures including providing baseline data for parameterising infectious disease mathematical models including those assessing the impact of clinical interventions such as pneumococcal conjugate vaccines.

Influence of Obesity on Pneumococcus Infection Risk in the Elderly

Obesity negatively affects immune function and host defense mechanisms. Obesity is associated with chronic activation of the innate immune system and consequent local and systemic inflammation which contribute to pathologic conditions such as type-2 diabetes mellitus, cancer, psoriasis, atherosclerosis, and inflammatory bowel disease. Individuals with obesity have increased susceptibility to contract viral, bacterial, and fungal infections and respond sub-optimally to vaccination. In this review, we summarize research findings on the effects of obesity on immune responses to respiratory tract infections (RTI), focusing on Streptococcus pneumoniae ("pneumococcus") infection, which is a major cause of morbidity and mortality in the US, causing community-acquired infections such as pneumonia, otitis media and meningitis. We show that the risk of infection is higher in elderly individuals and also in individuals of certain ethnic groups, although in a few reports obesity has been associated with better survival of individuals admitted to hospital with pneumococcus infection, a phenomenon known as "obesity paradox." We discuss factors that are associated with increased risk of pneumococcal infection, such as recent infection with RTI, chronic medical conditions, and immunosuppressive medications.

Chemical Synthesis of Rare, Deoxy-Amino Sugars Containing Bacterial Glycoconjugates as Potential Vaccine Candidates

Bacteria often contain rare deoxy amino sugars which are absent in the host cells. This structural difference can be harnessed for the development of vaccines. Over the last fifteen years, remarkable progress has been made toward the development of novel and efficient protocols for obtaining the rare sugar building blocks and their stereoselective assembly to construct conjugation ready bacterial glycans. In this review, we discuss the total synthesis of a variety of rare sugar containing bacterial glycoconjugates which are potential vaccine candidates.

Immunization rates of pneumococcal, influenza and tetanus vaccines and knowledge and attitudes of adult patients who receive inpatient treatment at hospital: Point prevalence study

The safety of vaccines, access to health care, the level of community's knowledge and the attention of physicians play a critical role in the rate of adult vaccination. This study aims to determine the immunization rate of pneumococcal, influenza and tetanus vaccines among the patients and their knowledge and attitudes in the hospital. The study is a cross-sectional point prevalence survey. The patients who agreed to participate in the study were interviewed using a questionnaire. Patients' gender, occupation, educational status, income level and risk factors (immunosuppressed and over 65 years old) were compared with the knowledge and attitudes about vaccinations. Of the 251 participants, 51.4% were female and 48.6% were male. The self-reported vaccination rate was 3.5% for pneumococcal, 8.6% for influenza and 26.6% for tetanus. Most of the patients have knowledge about influenza vaccination (90.3%). Patients with the high education level have significantly higher knowlege about tetanus vaccination and higher rate of tetanus vaccine compared to those with low education level (p = 0.04; p = 0.006). It was found that those with higher income levels had the more pneumococcal vaccination, more knowledge on tetanus vaccination, and more attitude that tetanus vaccine is necessary compared to those with lower income level (p < 0.05). Patients without risk factors have a higher rate of tetanus vaccination compared to those with risk factors (p < 0.001). It was inferred that the high level of education and income have a positive effect on the patients vaccination rates and their knowledge and attitude.

Maternal pneumococcal nasopharyngeal carriage and risk factors for neonatal carriage after the introduction of pneumococcal conjugate vaccines in The Gambia

OBJECTIVES

Pneumococcal nasopharyngeal carriage occurs early in life. However, the role of vertical transmission is not well understood. The aims of this study were to describe carriage among mothers and their newborns, and to assess for risk factors for neonatal carriage.

METHODS

In a nested retrospective cohort study, we analysed data from the control arm of a randomized controlled trial conducted in The Gambia 2 to 3 years after introduction of pneumococcal conjugate vaccine (PCV) 13. Nasopharyngeal swabs were collected from 374 women and their newborns on the day of delivery, then 3, 6, 14 and 28 days later. Pneumococci were isolated and serotyped using conventional microbiologic methods.

RESULTS

Carriage increased from 0.3% (1/373) at birth to 37.2% (139/374) at day 28 (p <0.001) among neonates and from 17.1% (64/374) to 24.3% (91/374) (p 0.015) among women. In both groups, PCV13 vaccine-type (VT) serotypes accounted for approximately one-third of the pneumococcal isolates, with serotype 19A being the most common VT. Maternal carriage (adjusted odds ratio (OR) = 2.82; 95% confidence interval (CI), 1.77-4.80), living with other children in the household (adjusted OR = 4.06; 95% CI, 1.90-8.86) and dry season (OR = 1.98; 95% CI, 1.15-3.43) were risk factors for neonatal carriage. Over half (62.6%) of the neonatal carriage was attributable to living with other children in the same household.

CONCLUSIONS

Three years after the introduction of PCV in The Gambia, newborns are still rapidly colonized with pneumococcus, including PCV13 VT. Current strategies for pneumococcal control in Africa do not protect this age group beyond the herd effect.

Prevalence and Etiology of Bacteremia in Febrile Children with Sickle Cell Disease at a Nigeria Tertiary Hospital

Background & Objectives

As a result of immune defects in Sickle cell disease (SCD), affected individuals are prone to infection from encapsulated bacterial pathogens like Streptococcus Pneumoniae. Studies on the etiological agents of bacteremia in children with SCD in Nigeria are few and have revealed a spectrum of organisms that is different from those recorded in other parts of the world.

Aim and Objectives

The objectives of this study were to determine the prevalence of bacteremia, etiological agents and antibiotic susceptibility pattern in febrile children with SCD attending the University College Hospital (UCH), Ibadan, Nigeria.

Methods

The study was cross-sectional and took place at the Department of Pediatrics of the UCH, Ibadan. Children with SCD, ages 0–17 years presenting with axillary temperature ≥ 38°C were enrolled after obtaining informed consent. History was obtained and complete physical examination performed after which blood was collected for culture and antibacterial susceptibility tests.

Results

A total of 116 children were studied of which 69 (59.5%) were males, 111 (95.7%) were of the Hemoglobin SS phenotype and 5 (4.3%) of the Hemoglobin SC phenotype. Bacteremia was present in 16 (13.8%) of the 116 children. Gram negative bacteria constituted 10 (62.5%) of all isolates, while the predominant isolates were Klebsiella pneumoniae 4, (25%) and Staphylococcus aureus, 4 (25%). Over 80% of the isolates were susceptible to Ceftriaxone, Amikacin and Meropenem.

Conclusions

Klebsiella pneumoniae and Staphylococcus aureus are the predominant causes of bacteremia in children with SCD in Ibadan, contrary to findings in western countries.

Streptococcus pneumoniae serotype 1 burden in the African meningitis belt: exploration of functionality in specific antibodies

Streptococcus pneumoniae serotype 1 (Sp1) constitutes an important cause of seasonal endemic meningitis in all age groups in the African meningitis belt. Despite a higher meningitis incidence, the Burkinabé population has an Sp1-specific antibody seroprevalence similar to that reported in the United Kingdom (UK). We aimed to establish whether the opsonophagocytic activity (OPA) of pneumococcal IgG naturally present in Burkina Faso differs from that seen in individuals in the UK and to compare the OPAs generated by natural and vaccine-induced immunity. Samples collected from pneumococcal vaccine-naive Burkinabé and UK subjects were matched for age (1 to 39 years) and anti-Sp1 IgG level, analyzed for OPA to 3 S. pneumoniae serotypes (1, 5, and 19A), and compared to postvaccine samples. Furthermore, the Burkinabé samples were assessed for IgG avidity and serotype-specific IgM concentrations. One hundred sixty-nine matched serum samples from both populations were selected. A greater proportion of Burkinabé subjects aged 1 to 19 years had functional Sp1 activity (OPA ≥ 8) compared to UK subjects (12% versus 2%, P < 0.001); however, the proportions were similar among adults (9%). The correlation between Sp1 IgG concentration and OPA was good (P < 0.001), but many individuals had nonfunctional IgG, which was not related to avidity. While the Sp1 IgM concentrations correlated with OPA, not all of the function in serum samples with low IgG could be attributed to IgM. Finally, vaccine-induced Sp1-specific IgG was more functional than equivalent amounts of naturally occurring IgG. In conclusion, despite a substantially higher pneumococcal meningitis incidence, no decreased functional immunity to Sp1 could be evidenced in the Burkinabé population compared to that in the population from the UK. Furthermore, the naturally induced antibodies were less functional than vaccine-induced antibodies.

Antipneumococcal seroprevalence and pneumococcal carriage during a meningococcal epidemic in Burkina Faso, 2006

BACKGROUND

To better understand the high incidence of pneumococcal meningitis in the African meningitis belt, we conducted a pneumococcal seroprevalence study during a meningococcal meningitis epidemic in Western Burkina Faso, March 2006.

METHODS

In 3 villages experiencing epidemics, we included 624 healthy persons (1-39 years) by cluster sampling. We determined pneumococcal serum immunoglobulin G (IgG) antibody concentrations against 12 serotypes contained in 13-valent pneumococcal conjugate vaccine, and evaluated determinants for IgG ≥ 0.35 μg/mL by multivariate logistic regression.

RESULTS

The percentage of subjects with serotype-specific IgG concentrations ≥0.35 μg/mL increased with age and was similar for the different serotypes: it was 20%-43% among 1-4-year-olds and 56%-90% among 20-39-year-olds. Prevalence of IgG ≥ 0.35 μg/mL against serotype 1 was up to 71% after age 10 years. During multivariate analyses, determinants of IgG concentrations ≥0.35 μg/mL varied by serotype; for 5 and 6 serotypes, respectively, female sex (around 2-fold increased odds) and cigarette smoking (about 5-fold reduced odds) predicted elevated titers.

CONCLUSIONS

Despite a substantially higher historical pneumococcal meningitis incidence in Burkina Faso, the general population has an antibody seroprevalence against 12 pneumococcal serotypes similar to that reported from the United Kingdom. The role of putatively protective antibody seroprevalence in preventing pneumococcal meningitis in the meningitis belt requires more thorough evaluation.

The changing epidemiology of childhood pneumococcal disease in Korea

The wide use of antimicrobial agents and 7-valent pneumococcal conjugate vaccine (PCV7) has led to major changes in the epidemiology of childhood pneumococcal diseases. In Korea, data on the population-based incidence of childhood invasive pneumococcal diseases (IPD) are not available; however, institution-based surveillance data suggest a substantial burden of childhood IPD. Following the introduction of the PCV7 in Korea in 2003, the proportion of IPD caused by vaccine-type pneumococci has decreased, while non-PCV7 serotypes, especially serotypes 19A and 6A, whose proportions had been increasing before the introduction of the vaccine, became predominant among childhood IPD isolates. This article reviews the overall impact of PCV7 utilization and summarizes the results obtained so far. Continuous monitoring and gathering of scientific evidence for the epidemiological transition of pneumococcal carriage and IPD will be important for the management of pneumococcal infections in Korea.

Pediatric invasive pneumococcal disease in the United States in the era of pneumococcal conjugate vaccines

Invasive infections caused by Streptococcus pneumoniae continue to be a major cause of morbidity and mortality worldwide, especially in children under 5 years of age. In the United States, 90% of invasive pneumococcal infections in children are caused by 13 serotypes of S. pneumoniae. The licensure (in 2000) and subsequent widespread use of a heptavalent pneumococcal conjugate vaccine (PCV7) have had a significant impact on decreasing the incidence of serious invasive pneumococcal disease (IPD) in all age groups, especially in children under 2 years of age. However, the emergence of replacement non-PCV7 serotypes, especially serotype 19A, has resulted in an increase in the incidence of serious and invasive infections. In 2010, a 13-valent PCV was licensed in the United States. However, the impact that this vaccine will have on IPD remains to be seen. The objectives of this review are to discuss the epidemiology of serious and invasive pneumococcal infections in the United States in the PCV era and to review some of the pneumococcal vaccines that are in development.

Signal identification and evaluation for risk of febrile seizures in children following trivalent inactivated influenza vaccine in the Vaccine Safety Datalink Project, 2010-2011

In fall 2010 in the southern hemisphere, an increased risk of febrile seizures was noted in young children in Australia in the 24 h after receipt of trivalent inactivated influenza vaccine (TIV) manufactured by CSL Biotherapies. Although the CSL TIV vaccine was not recommended for use in young children in the US, during the 2010-2011 influenza season near real-time surveillance was conducted for febrile seizures in the 0-1 days following first dose TIV in a cohort of 206,174 vaccinated children ages 6 through 59 months in the Vaccine Safety Datalink Project. On a weekly basis, surveillance was conducted with the primary approach of a self-controlled risk interval design and the secondary approach of a current vs. historical vaccinee design. Sequential statistical methods were employed to account for repeated analyses of accumulating data. Signals for seizures based on computerized data were identified in mid November 2010 using a current vs. historical design and in late December 2010 using a self-controlled risk interval design. Further signal evaluation was conducted with chart-confirmed febrile seizure cases using only data from the primary approach (i.e. self-controlled risk interval design). The magnitude of the incidence rate ratio and risk difference comparing risk of seizures in the 0-1 days vs. 14-20 days following TIV differed by receipt of concomitant 13-valent pneumococcal conjugate vaccine (PCV13). Among children 6-59 months of age, the incidence rate ratio (IRR) for TIV adjusted for concomitant PCV13 was 2.4 (95% CI 1.2, 4.7) while the IRR for PCV13 adjusted for concomitant TIV was 2.5 (95% CI 1.3, 4.7). The IRR for concomitant TIV and PCV13 was 5.9 (95% CI 3.1, 11.3). Risk difference estimates varied by age due to the varying baseline risk for seizures in young children, with the highest estimates occurring at 16 months (12.5 per 100,000 doses for TIV without concomitant PCV13, 13.7 per 100,000 doses for PCV13 without concomitant TIV, and 44.9 per 100,000 doses for concomitant TIV and PCV13) and the lowest estimates occurring at 59 months (1.1 per 100,000 doses for TIV without concomitant PCV13, 1.2 per 100,000 doses for PCV13 without concomitant TIV, and 4.0 per 100,000 doses for concomitant TIV and PCV13). Incidence rate ratio and risk difference estimates were lower for children receiving TIV without concomitant PCV13 or PCV13 without concomitant TIV. Because of the importance of preventing influenza and pneumococcal infections and associated complications, our findings should be placed in a benefit-risk framework to ensure that population health benefits are maximized.

Streptococcus pneumoniae vaccination in older adults

BACKGROUND

Streptococcus pneumoniae infections are a major cause of morbidity and mortality in older adults. Vaccination in older adults is intended to prevent S pneumoniae infections, yet little information is available regarding its efficacy in this patient population.

OBJECTIVE

The aim of this article was to review the current literature to determine the efficacy and tolerability of S pneumoniae vaccination in older adults.

METHODS

PubMed (1950-present) and EMBASE (1974-present) were searched using the search terms Streptococcus pneumoniae immunization, pneumococcus immunization, pneumococcus vaccine, and aged. Additional articles were identified from the reference lists of included studies. Studies were included if they reported information in older (55-<65 years) and elderly (≥65 years) adults and were related to at least 1 of the following topics: epidemiology of S pneumoniae, estimates of vaccine coverage, recommendations for vaccination, tolerability, and efficacy and/or effectiveness of vaccination against S pneumoniae.

RESULTS

Six randomized controlled trials and 18 observational studies that evaluated the efficacy of pneumococcal vaccination in older and elderly adults were reviewed. Findings from evaluations of efficacy, as measured by clinical outcomes and immunogenicity, in older adults have been conflicting, with some subsets of prospective, well-controlled studies finding little benefit, whereas findings from several retrospective studies have suggested significant benefit. This discord may have been a result of the limited power of the prospective subanalyses to detect significant differences.

CONCLUSIONS

In light of the potential clinical benefit and few reports of serious adverse events, vaccination in older adults is likely warranted. Prospective, well-controlled studies are needed to better quantitatively evaluate the benefit of pneumococcal vaccine in older adults.

Pneumococcal conjugate vaccine given shortly after birth stimulates effective antibody concentrations and primes immunological memory for sustained infant protection

Immunization of Kenyan newborns with 7-valent pneumococcal conjugate vaccine is safe and immunogenic. Compared with the Expanded Programme on Immunization schedule beginning at 6 weeks, it stimulates similar antibody concentrations at 18 weeks and induces equal responses to a 9-month booster dose.

Background. In developing countries, newborn immunization with pneumococcal conjugate vaccines (PCVs) could protect young infants who are at high risk of invasive pneumococcal disease (IPD) but might lead to immune tolerance.

Methods. In a randomized trial, young infants received 7-valent PCV at 6, 10, and 14 weeks (Expanded Programme on Immunization [EPI] group) or 0, 10, and 14 weeks (newborn group). Safety was monitored actively at 2–7 days and then passively. Serum samples obtained at birth and 6, 10, 14, 18, 36, and 37 weeks were assayed by enzyme-linked immunosorbent assay for anticapsular immunoglobulin G concentration and avidity. Infants were boosted with either 7-valent PCV or one-fifth dose of pneumococcal polysaccharide vaccine at 36 weeks. Nasopharyngeal swab samples were obtained at 18 and 36 weeks.

Results. Three-hundred neonates and young infants were enrolled. Newborn vaccination was well tolerated. Adverse events occurred equally in each group; none was related to immunization. One infant, immunized at birth, died of unrelated neonatal sepsis. At 18 weeks, protective concentrations (≥0.35 μg/mL) were achieved against each serotype by ≥87% of infants with no significant differences between groups. Geometric mean concentrations were higher in the EPI group for serotypes 4, 9V, 18C, and 19F at 18 weeks and for serotype 4 at 36 weeks. Avidity was greater in the newborn group for serotypes 4, 6B, and 19F at 18 weeks and for serotype 19F at 36 weeks. Booster responses and vaccine-type/nonvaccine-type carriage prevalence did not differ between groups.

Conclusions. PCV was safe, immunogenic, and primed for memory when given at birth. There was no evidence of immune tolerance. Vaccination beginning at birth offers an alternative to control IPD in vulnerable young infants.

The burden of pneumococcal disease in children less than 5 years of age in Abu Dhabi, United Arab Emirates

BACKGROUND AND OBJECTIVE

Streptococcus pneumoniae is a major cause of mortality and morbidity in both developing and industrialized countries, especially among young children and in both immunocompromised and immunocompetent individuals. It is implicated in both invasive (e.g. meningitis and septicemia) as well as noninvasive disease (community-acquired pneumonia and otitis media). The objective of the current study was to describe the overall epidemiology of both invasive and noninvasive pneumococcal disease in Abu Dhabi over a 5-year period.

DESIGN AND SETTING

Retrospective review of all pediatric (≤ 5 year old) pneumococcal disease admissions to Shaikh Khalifa Medical City (SKMC) and Mafraq Hospital in Abu Dhabi from 1 January 2001 till 31 December 2005.th

METHODS

We retrieved computerized data from the health information management systems (International Classification of Diseases, 9th Revision (ICD9) diagnosis codes) as well as manual surveillance in the laboratory record of pneumococcal isolates.

RESULTS

The incidence of invasive pneumococcal disease was 13.6/100, 000 per year (95% CI, 6.5-24.9) and the incidence of noninvasive pneumococcal disease was 172.5/100,000 per year (95% CI, 143.8-205.2). The total incidence rate was 186.0/100, 000 per year (95% CI, 156.2-219.9).

CONCLUSION

This epidemiological survey indicates that the incidence rates in the United Arab Emirate are higher than in Western countries where conjugate pneumococcal vaccine has been introduced. This study is important as it documents the incidence of pneumococcal disease in the era before introduction of the conjugate pneumococcal vaccine and allows for future research to document the impact of a new vaccine considering the geographic variation of pneumococcal serotypes.

Chemical synthesis of bacterial lipoteichoic acids: an insight on its biological significance

During infections caused by Gram-negative bacteria, lipopolysaccharide (LPS, endotoxin) has a dominant role leading to fulminant pro-inflammatory reactions in the host. As there is no LPS in Gram-positive bacteria, other microbial cell wall components have been identified to be the causative agent for the pro-inflammatory activity since also Gram-positive bacterial infections lead to comparable clinical symptoms and reactions. On search for the "Gram-positive endotoxin" a widely accepted hypothesis has been raised in that the lipoteichoic acids (LTAs) serve as pathogen-associated molecular patterns (PAMPs) during Gram-positive sepsis, although the amount necessary for a pro-inflammatory in vitro response is several orders of magnitude higher than that for LPS. Therefore, LTA cannot be considered to be "the (endo)toxin of Gram-positive bacteria". Although LPS and LTA show structural relatedness (amphiphilic, negatively charged glycophospholipids), they are structurally quite different from each other and one might expect that they are also recognized by different receptors of the innate immune system, the so called toll-like receptors 4 and 2 (TLR4 and TLR2), respectively. Based on their chemical structure, the LTAs were classified into four types (type I-IV) of which we have carefully investigated the LTA of Staphylococcus aureus (type I), Lactococcus garvieae (type II) and Streptococcus pneumoniae (type IV). Hence, these LTAs have been synthesized in our group and biologically evaluated with respect to their potency to activate cytokines in transiently TLR2/CD14-transfected human endothelial kidney cells (HEK 293) or human macrophages and whole blood cells. Although LTA of type I and IV are structurally quite different, especially in their hydrophilic moiety, they originally were believed to interact with the same receptor (TLR2). Hence, the chemical syntheses leading to structurally defined, non-contaminated stimuli have a major impact on the outcome and interpretation of these biological studies of the innate immune system. With this material, it became evident that synthetic LTA from S. aureus and S. pneumoniae are not recognized by TLR2. Instead, another receptor of the innate immune system, the lectin pathway of the complement, known since many years to interact with LTA in quite a specific way, has gained increasing attractivity. With the help of synthetic LTA we obtained first evidences that this receptor is indeed the pathogen recognition receptor (PRR) for LTA.

Invasive pneumococcal disease in children prior to implementation of the conjugate vaccine in the Zurich region, Switzerland

OBJECTIVE

To describe symptoms, disease manifestations and outcome of invasive pneumococcal disease in children prior to implementation of the pneumococcal vaccine.

PATIENTS AND METHODS

Analysis of children younger than 16 years of age with invasive pneumococcal disease (IPD; n = 119). Children with culture-confirmed IPD, without underlying illness at risk for invasive disease, were included.

RESULTS

IPD in 90 children (age: median 2, mean 3.2 years) included 15 with meningitis, 16 with septicaemia, 14 with bacteraemia, 24 with pneumonia and 21 with skin, bone and joint infections. Symptoms of IPD most often described were fever and gastrointestinal symptoms (abdominal pain, vomiting, or diarrhoea), and coughing. More than 90% of children with pneumonia were coughing. Most importantly, clinical signs significantly predictive for severe IPD included tachycardia for sepsis, tachypnea for pneumonia, and meningeal signs for meningitis. Leukocyte, neutrophil and platelet counts were lower and C-reactive protein concentrations were higher on admission in children with complicated than in children with uncomplicated IPD but, due to wide overlap of these numbers, the difference was not of prognostic help to predict clinical course and outcome. Overall, 40% of children with IPD manifested complications and IPD showed a mortality rate of 6.6%.

CONCLUSIONS

IPD is a serious disease with a high complication rate and mortality. The clinical signs tachycardia, tachypnea, and meningism were highly predictive for severe IPD. The initial clinical presentation and laboratory evaluation were mostly unpredictable with respect to complications and outcome in contrast to the clinical signs.

Heptavalent pneumococcal conjugate vaccine immunogenicity in very-low-birth-weight, premature infants

BACKGROUND

The heptavalent pneumococcal CRM197 conjugate vaccine (PCV-7) has been incompletely studied in very-low-birth-weight (< or =1500 g) infants.

OBJECTIVE

To assess PCV-7 immunogenicity in very-low-birth-weight, premature infants. We hypothesized that the frequency of postvaccine antibody concentrations > or =0.15 microg/mL would vary directly with birth weight.

METHODS

This was a multicenter observational study. Infants 401 to 1500 g birth weight and <32 0/7 weeks gestation, stratified by birth weight, were enrolled from 9 National Institute of Child Health and Human Development Neonatal Research Network centers. Infants received PCV-7 at 2, 4, and 6 months after birth and had blood drawn 4 to 6 weeks following the third dose. Antibodies against the 7 vaccine serotypes were measured by enzyme-linked immunosorbent assay.

RESULTS

Of 369 enrolled infants, 244 completed their primary vaccine series by 8 months and had serum obtained. Subjects were 27.8 +/- 2.2 (mean +/- standard deviation) weeks gestation and 1008 +/- 282 g birth weight. Twenty-six percent had bronchopulmonary dysplasia and 16% had received postnatal glucocorticoids. Infants 1001 to 1500 g birth weight were more likely than those 401 to 1000 g to achieve antibody concentrations > or =0.15 microg/mL against the least 2 immunogenic serotypes (6B: 96% vs. 85%, P = 0.003 and 23F: 97% vs. 88%, P = 0.009). In multiple logistic regression analysis, lower birth weight, postnatal glucocorticoid use, lower weight at blood draw, and Caucasian race were each independently associated with antibody concentrations <0.35 microg/mL against serotypes 6B and/or 23F.

CONCLUSIONS

When compared with larger premature infants, infants weighing < or =1000 g at birth have similar antibody responses to most, but not all, PCV-7 vaccine serotypes.

African meningitis belt pneumococcal disease epidemiology indicates a need for an effective serotype 1 containing vaccine, including for older children and adults

Background

Pneumococcal conjugate vaccine strategies in GAVI-eligible countries are focusing on infant immunization but this strategy may not be optimal in all settings. We aimed to collect all available population based data on pneumococcal meningitis throughout life in the African meningitis belt and then to model overall meningitis risk to help inform vaccine policy.

Methods

After a systematic review of literature published from 1970 through the present, we found robust population-based Streptococcus pneumoniae (Sp) meningitis data across age strata for four African meningitis belt countries that included 35 surveillance years spanning from 1970 to 2005. Using these data we modeled disease risk for a hypothetical cohort of 100,000 persons followed throughout life.

Results

Similar to meningococcal meningitis, laboratory-confirmed pneumococcal meningitis was seasonal, occurring primarily in the dry season. The mean annual Sp meningitis incidence rates were 98, 7.8 to 14, and 5.8 to 12 per 100,000 among persons <1, 1 through 19, and 20 to 99 years of age, respectively, which (in the absence of major epidemics) were higher than meningococcal meningitis incidences for persons less than 1 and over 20 years of age. Mean Sp meningitis case fatality ratios (CFR) among hospitalized patients ranged from 36-66% depending on the age group, with CFR exceeding 60% for all age groups beyond 40 years; depending on the age group, Sp meningitis mortality incidences were 2 to 12-fold greater than those for meningococcal meningitis. The lifetime risks of pneumococcal meningitis disease and death were 0.6% (1 in 170) and 0.3% (1 in 304), respectively. The incidences of these outcomes were highest among children age <1 year. However, the cumulative risk was highest among persons age 5 to 59 years who experienced 59% of pneumococcal meningitis outcomes. After age 5 years and depending on the country, 59-79% of meningitis cases were caused by serotype 1.

Conclusions

In the African meningitis belt, Sp is as important a cause of meningitis as Neisseria meningitidis, particularly among older children and working age adults. The meningitis belt population needs an effective serotype 1 containing vaccine and policy discussions should consider vaccine use outside of early childhood.

Vaccine preventable diseases and vaccination policy for indigenous populations

There are many similarities regarding the health status of Indigenous people in the 4 English-speaking developed countries of North America and the Pacific (United States, Canada, Australia, New Zealand), where they are all now minority populations. Although vaccines have contributed to the reduction or elimination of disease disparities for many infections, Indigenous people continue to have higher morbidity and mortality from many chronic and infectious diseases compared with the general populations in their countries. This review summarizes the available data on the epidemiology of vaccine-preventable diseases in Indigenous populations in these 4 countries in the context of the vaccination strategies used and their impact, with the aim of identifying successful strategies with the potential for wider implementation.

Association of respiratory virus activity and environmental factors with the incidence of invasive pneumococcal disease

OBJECTIVES

To correlate the incidence rate of invasive pneumococcal disease (IPD) with fluctuations in respiratory virus activity and environmental factors in Christchurch, New Zealand.

METHODS

Ecological study comparing incidence rates of IPD with incidence rates of respiratory virus detection, meteorologic and air pollution data during 1995-2006. The relationship between annualized monthly rates of IPD and annualized monthly rates of respiratory virus detection and monthly meteorologic recordings and air pollution data was assessed using Spearman's rank correlation coefficient and negative binomial regression analysis.

RESULTS

Incidence rates of IPD were statistically significantly correlated with increasing detection rates of influenza viruses, respiratory syncytial virus (RSV), adenovirus and parainfluenza virus 3. Furthermore, rates of IPD were statistically significantly correlated with decreasing daily temperature, sunshine hours and wind speed, and with increasing air pollution levels and humidity. After regression analysis, the only statistically significant associations in the total population were between influenza virus activity, parainfluenza virus 3 activity and air pollution levels and increased rates of IPD, although RSV activity was associated with increased rates of IPD in children <5 years old.

CONCLUSIONS

Incidence rates of IPD are associated with the increased activity of some respiratory viruses and with air pollution in Christchurch.

Trends in bacteremia in the pre- and post-highly active antiretroviral therapy era among HIV-infected children in the US Perinatal AIDS Collaborative Transmission Study (1986-2004)

OBJECTIVE

HIV-infected children are at high risk for bacteremia. Highly active antiretroviral therapy has reduced rates of opportunistic infections; less is known about its effect on pediatric bacteremia rates. Thus, we sought to determine its impact on bacteremia incidence in HIV-infected children.

METHODS

Children born during 1986-1998 were followed until 2004 in the Perinatal AIDS Collaborative Transmission Study. We determined the pre- and post-highly active antiretroviral therapy (before and after January 1, 1997) incidence of bacteremia among HIV-infected children and characterized the CD4% temporal declines and mortality among patients with and those without incident bacteremias.

RESULTS

Among 364 children, 68 had 118 documented bacteremias, 97 before and 21 after January 1, 1997. Streptococcus pneumoniae constituted 56 (58%) pre- and 13 (62%) post-highly active antiretroviral therapy cases. The incidence rate ratio of bacteremias comparing post- versus pre-highly active antiretroviral therapy was 0.3 overall and 0.2, 0.2, and 0.4 among children aged 0 to 24, 25 to 48, and 49 to 72 months, respectively. Kaplan-Meier analysis for time to first bacteremia in children born during the pre-highly active antiretroviral therapy compared with the post-highly active antiretroviral therapy era revealed that 69% and 94%, respectively, remained bacteremia free at a median follow-up of 6 years. The Cox proportional hazards model also showed a significant reduction of bacteremias in the post-highly active antiretroviral therapy era, even after controlling for gender and race. Among children <6 years of age, those who experienced bacteremia had faster temporal CD4% decline than those who never had bacteremia. Survival analysis revealed that HIV-infected children with bacteremia experienced higher overall mortality when controlling for gender, race, and clinic site.

CONCLUSIONS

A significant decrease in bacteremia incidence and a prolongation in the time to first bacteremia incident were seen in the post-highly active antiretroviral therapy era. Children with a steeper decline of CD4 T cells were more likely to develop bacteremia. Children who experienced bacteremia had an associated higher mortality than their bacteremia-free counterparts.

Bacterial Infections

In Osier’s time, bacterial pneumonia was a dreaded event, so important that he borrowed John Bunyan’s characterization of tuberculosis and anointed the pneumococcus, as the prime pathogen, “Captain of the men of death.”1 One hundred years later much has changed, but much remains the same. Pneumonia is now the sixth most common cause of death and the most common lethal infection in the United States. Hospital-acquired pneumonia is now the second most common nosocomial infection.2 It was documented as a complication in 0.6% of patients in a national surveillance study,3 and has been reported in as many as 20% of patients in critical care units.4 Furthermore, it is the leading cause of death among nosocomial infections.5 Leu and colleagues6 were able to associate one third of the mortality in patients with nosocomial pneumonia to the infection itself. The increase in hospital stay, which averaged 7 days, was statistically significant. It has been estimated that nosocomial pneumonia produces costs in excess of $500 million each year in the United States, largely related to the increased length of hospital stay.

Invasive pneumococcal disease among children in a health district of Barcelona: early impact of pneumococcal conjugate vaccine

This study evaluated the impact of heptavalent pneumococcal conjugate vaccine (HPCV) on invasive pneumococcal disease (IPD) in children aged < or = 5 years in Barcelona, Spain. The incidence of IPD, vaccine uptake and prevalence of nasopharyngeal colonisation were analysed in two different periods: 1999-2001 (pre-licence period), and 2002-2004 (post-licence period). In total, 121 cases of IPD were identified. The overall incidence of IPD decreased from 96.9 cases/100,000 to 90.6 cases/100,000 (OR 0.93, 95% CI 0.69-1.26, p 0.71) between the two periods. The proportion of cases caused by non-vaccine-related serotypes (NVS) increased from 21% to 43.7% (OR 2.9, 95% CI 1.2-7, p 0.01). IPD was diagnosed in seven vaccinated children, six of whom were infected by NVS. There was a trend of diminishing prevalence of resistance to penicillin and macrolides in 2002-2004. The incidence of empyema increased from 1.7 to 8.5/100,000 (OR 4.5, 95% CI 0.91-18, p 0.06). The rate of vaccination ranged from 4.8% to 34%. It was concluded that the rates of IPD in this area did not decrease following the introduction of HPCV. The low uptake of vaccine and the greater proportion of colonisation/infection by NVS probably explain these findings. A trend of increasing empyema was also apparent. A decrease in the prevalence of penicillin and macrolide resistance paralleled the progressive uptake of vaccine.

Comparison of lipoteichoic acid from different serotypes of Streptococcus pneumoniae

Pneumococcal lipoteichoic acid (LTA) is known to have a completely different chemical structure compared with that of Staphylococcus aureus: the polyglycerophosphate in the backbone is replaced in the pneumococcal LTA by a pentamer repeating unit consisting of one ribitol and a tetrasaccharide carrying the unusual substituents phosphocholine and N-acetyl-D-galactosamine. Neither D-alanine nor N-acetyl-D-glucosamine, which play central roles in the biological activity of the staphylococcal LTA, has been reported. The extraction using butanol is more gentle compared with the previously reported chloroform-methanol extraction and results in a higher yield of LTA. We characterized the LTA of two different strains of Streptococcus pneumoniae:R6 (serotype 2) and Fp23 (serotype 4). NMR analysis confirmed the structure of LTA from R6 but showed that its ribitol carries an N-acetyl-D-galactosamine substituent. The NMR data for the LTA from Fp23 indicate that this LTA additionally contains ribitol-bound D-alanine. Dose-response curves of the two pneumococcal LTAs in human whole blood revealed that LTA from Fp23 was significantly more potent than LTA from R6 with regard to the induction of all cytokines measured (tumor necrosis factor, interleukin-1 (IL-1), IL-8, IL-10, granulocyte colony-stimulating factor, and interferon gamma). However, other characteristics, such as lack of inhibition by endotoxin-specific LAL-F, Toll-like receptor 2 and not 4 dependence, and lack of stimulation of neutrophilic granulocytes, were shared by both LTAs. This is the first report of a difference in the structure of LTA between two pneumococcal serotypes resulting in different immunostimulatory potencies.

Cost-effectiveness of vaccinating for invasive pneumococcal disease in the elderly in the Lazio region of Italy

Pneumococcal vaccination among the elderly is currently recommended in several western countries. We estimated the cost-effectiveness of a hypothetical vaccination campaign of 65+ year olds in the Lazio region (Italy). Baseline net costs per event averted and life-year gained, at 2001 prices, were euro 34,681 (95%CI: euro 28,699 to euro 42,929) and euro 23,361, respectively (95%CI: euro 16,419 to euro 38,297). Lower bacteraemic pneumonia incidence and vaccine effectiveness increased the net cost per life-year gained (ICER) to euro 53,899 and euro 74,313, respectively; in the best-case scenario the ICER was euro 4249. The case definition of invasive pneumococcal disease and, consequently, vaccine effectiveness are major uncertainties in countries with low incidence of pneumonia.

Cellulitis in childhood invasive pneumococcal disease: a population-based study

AIM

There are few detailed data on the age-specific incidence and clinical pattern of pneumococcal cellulitis in children. We conducted a retrospective review of cellulitis as a subset of prospectively collected laboratory-identified invasive pneumococcal disease (IPD) and performed a systematic review of published literature.

METHODS

Prospective laboratory surveillance in urban regions of New South Wales, Australia, 1 June 1997-31 December 2001. Medical notes reviewed for each identified case and defined literature search strategy applied.

RESULTS

There were 1067 cases of IPD in children aged 0-17 years; 38 (3.3%) were cellulitis (32 periorbital, 6 buccal). Compared with other types of IPD, a greater proportion of cellulitis cases occur in children<2 years (30/38, 79% vs. 617/1029, 60.0%; P=0.004) in whom underlying illness was less common (0/30, 0% vs. 53/590, 9%; P=0.06). Initially, another diagnosis was made in 13 (34%) of cases; only five had a lumbar puncture, all normal. Of the 239 cases of pneumococcal cellulitis documented in the literature, 28 (11.7%) had the diagnosis made by means other than positive blood culture and 95% were facial or orbital with underlying illness (6%) and associated meningitis (1.9%) uncommon.

CONCLUSION

Cellulitis is an uncommon focus in IPD in children, and is almost always facial. Most cases occur under 2 years of age, are seldom associated with meningitis or other complications, and are frequently not recognised on admission.

The vaccine potential of Streptococcus pneumoniae surface lectin- and non-lectin proteins

We have fractionated S. pneumoniae surface proteins into lectin and non-lectin fractions and tested their ability to elicit protective immune responses in the mouse model system. The total cell wall protein fraction (CW-T) was separated into lectin (CW-L), and non-lectin (CW-NL) fractions and used for immunization of mice. Immunized mice were challenged intranasally or intraperitoneally with S. pneumoniae strain WU2 (serotype 3). CW-T, CW-NL and CW-L and adjuvant only vaccination protected 55%, 43%, 44% and 0% of the intranasally challenged mice, respectively and 67%, 86%, 11% and 0% of mice challenged intraperitoneally, respectively. Immunogenic proteins in each fraction were sequenced and identified using MALDI-TOF. CW-L proteins provided a significantly better protection against intranasal inoculation and CW-NL proteins provided a significantly better protection from intraperitoneal inoculation. Proteins identified by sera from mice immunized with the cell-wall derived fractions may constitute candidates for future development of anti S. pneumoniae vaccines.

Distribution of Streptococcus pneumoniae serotypes responsible for penicillin resistance and the potential role of new conjugate vaccines in New Caledonia

Invasive pneumococcal disease is a significant cause of morbidity and mortality worldwide. The aim of this study was to establish the serotypes responsible for pneumococcal disease and the serotypes responsible for penicillin resistance in Noumea, New Caledonia. Isolates of Streptococcus pneumoniae from all body sites referred to the Microbiology Department of the Pasteur Institute in New Caledonia between May 1999 and May 2001 had serotyping and susceptibility testing performed. Basic demographic data on patients were also collected. A total of 298 isolates were included in the study. The most common serotypes were types 1 (20%), 23F (10%), 12F (8%), 19F (8%), and 6B (5%). The serotype distribution differed significantly with age, site of collection, and ethnicity. Overall, 280 of 298 (94%) of the isolates had serogroups that are included in the 23-valent vaccine. However, only 14 of 20 (70%) of the isolates associated with invasive disease from children younger than 5 years of age and 26 of 113 (23%) of invasive isolates from patients more than 5 years of age were included in the new 7-valent conjugate vaccine. Overall, reduced susceptibility to penicillin was found in 43 of 298 (14.4%) of the isolates, with 13% falling into the intermediate resistance category and only 5 (2%) being high-level resistant. A higher prevalence of penicillin resistance occurred in younger age groups and in European patients and involved specifically certain serotypes. The 7-valent conjugate pneumococcal vaccine has potential benefit for the New Caledonian population under 5 years of age and should be considered for future vaccines schedules.

Implementing guidelines for the treatment of acute otitis media

The recently published Clinical Practice Guideline for the Diagnosis and Management of Acute Otitis Media represents a sincere effort by the AAP andthe AAFP to provide management guidelines for the practitioner based upon the best scientific evidence available. Despite many years of research and hundreds of clinical studies addressing various aspects of the epidemiology, clinical presentation, and treatment of acute otitis media, important questions remain unaddressed or have been addressed in a less than optimal fashion. These gaps in knowledge and deficiencies in several of the studies that formed the scientific basis for the proposed guidelines are the major reasons behind continued disagreement over certain recommendations. Until more comprehensive and careful analyses can be performed, disagreements are likely to persist. Even so, there is general agreement about most of the recommendations made in these guidelines, and these recommendations will provide a very valuable framework for the practicing physician as he or she cares for children with acute otitis media. To briefly review the major points, first is the critical importance of accurately diagnosing acute otitis media using a combination of clinical findings and observable abnormalities of the tympanic membrane and middle ear space. Particularly important is the differentiation of acute otitis media from otitis media with effusion. Second is the value of treating the pain associated with acute otitis media as a regular component of care, irrespective of any decision concerning antimicrobial treatment. Third is the option, for a select group of older patients with nonsevere disease, of withholding antimicrobial therapy for the first 48 to 72 hours, if close follow-up and active parental involvement can be guaranteed. Fourth is the recommendation that if an antimicrobial agent is used, high-dose amoxicillin (80 to 90 mg/kg/d) is the treatment of choice for most children at the time of initial presentation unless disease is particularly severe or the child has recently failed a previous course of the antibiotic. Finally highlighted is the importance of ongoing education efforts on the part of physicians in advising parents about the things they can do in their households to lessen the risk of future disease.

Streptococcus pneumoniae: description of the pathogen, disease epidemiology, treatment, and prevention

Streptococcus pneumoniae causes significant morbidity and mortality. Children younger than 2 years and individuals older than 65 years experience the highest rates of pneumococcal disease. Efforts to treat pneumococcal disease have been complicated by increasing resistance to antimicrobials. Prevention efforts have included the pneumococcal polysaccharide vaccines and the pneumococcal conjugate vaccines, with use of these vaccines targeted to those at highest risk for disease. Information and background on S. pneumoniae and pneumococcal disease are provided. Vaccines targeted at this pathogen are reviewed, and the clinical trials that evaluated their safety, efficacy, and effectiveness are summarized. Also provided are recommendations for use of these vaccines.

Post-PCV7 changes in colonizing pneumococcal serotypes in 16 Massachusetts communities, 2001 and 2004

OBJECTIVE

The introduction of heptavalent conjugate pneumococcal vaccine (PCV7) has raised concerns for replacement with nonvaccine serotypes in both invasive disease and asymptomatic carriage. Analysis of colonizing serotypes among healthy children in the community provides critical data on such changes.

METHODS

Nasopharyngeal specimens were obtained from children who were younger than 7 years during well-child or sick visits in primary care practices in 16 Massachusetts communities during 2001 and 2004. Susceptibility testing and serotyping were performed on isolated Streptococcus pneumoniae strains. Vaccination history with PCV7 was abstracted from the medical record.

RESULTS

Among colonizing pneumococcal isolates, PCV7 serotypes decreased from 36% to 14%, and non-PCV7 serotypes increased from 34% to 55%. Overall carriage did not change (26% to 23%); neither did carriage of potentially cross-reactive serotypes (30% to 31%). The most common non-PCV7 serotypes were serotypes 11, 15, and 29. There was a substantial increase in penicillin nonsusceptibility from 8% to 25% in non-PCV7 serotypes; 35% were highly resistant to penicillin. Penicillin nonsusceptibility increased from 45% to 56% among PCV7 serotypes while remaining stable among PCV7 potentially cross-reactive strains (51% vs 54%).

CONCLUSIONS

Pneumococcal colonization has changed after the introduction of PCV7, both in serotype distribution and in patterns of antibiotic resistance. The frequency of nonvaccine strains has increased, and the proportion of nonvaccine isolates that are not susceptible to penicillin has tripled. This shift toward increased carriage of nonvaccine serotypes warrants vigilance for changes in the epidemiology of invasive pneumococcal disease.

Méningites à pneumocoque de l'enfant en France : âge de survenue et facteurs de risques médicaux

Streptococcus pneumoniae (Sp) is an important cause of morbidity and mortality among paediatric infectious diseases. The aim of this study is to analyse specific data on Sp meningitis out of the Bacterial Meningitis (BM) French Surveillance Network about mean age of BM cases and clinical features. Overall 367 Sp BM were reported between January 2001 to January 2004 (sex ratio M/F: 1.3), 69.7% were < 2 years old, median age 0.8 year (minmax 0-16.8 years). Before two years old children, 94.1% had no medical risk factor and no underlying conditions: on the other hand, after two years old, these factors were reported in 27% cases (P < 0.001). Mortality rate was 10.9%. On account of a Sp BM's pic at five months, data of the BM French Surveillance Network confirm the necessity of an early vaccination. The vaccine administration at two, three, four months with a booster during the second year, recommended in the vaccinal french calendar, seems particularly adapted to the Sp BM in France.

Assignment of weight-based immunoglobulin G1 (IgG1) and IgG2 units in antipneumococcal reference serum lot 89-S(F) for pneumococcal polysaccharide serotypes 1, 4, 5, 7F, 9V, and 18C

Weight-based assignments for immunoglobulin G1 (IgG1) and IgG2 subclass antibodies to Streptococcus pneumoniae capsular polysaccharides (PnPs) in antipneumococcal standard reference serum lot 89-S (lot 89-S), also known as lot 89-SF, have been determined for serotypes 1, 4, 5, 7F, 9V, and 18C. This extends the usefulness of lot 89-S beyond the IgG1 and IgG2 subclass assignments for serotypes 3, 6B, 14, 19F, and 23F made previously (A. Soininen, H. Kayhty, I. Seppala, and T. Wuorimaa, Clin. Diagn. Lab. Immunol. 5:561-566, 1998) to cover 11 major serotypes associated with the highest percentage of pneumococcal disease worldwide. A method of equivalence of absorbances in enzyme immunosorbent assays was used to determine the IgG1 and IgG2 antibody concentrations for the additional serotypes in lot 89-S, based on the subclass values previously assigned for PnPs serotypes 6B, 14, and 23F. This cross-standardization method assures consistency with previous antibody assignments in that reference serum. The newly assigned subclass values for serotype 9V, and previously assigned values for serotype 14, were used to quantitate PnPs antibodies in sera from adult and pediatric subjects immunized with a pneumococcal conjugate vaccine. There was a predominance of IgG1 anti-PnPs antibodies in pediatric sera and IgG2 anti-PnPs antibodies in the adult sera. The IgG1 and IgG2 subclass assignments for the 11 PnPs serotypes in antipneumococcal standard reference serum lot 89-S are useful for quantitating and characterizing immune responses to pneumococcal infection and vaccination regimens.

The rate of serious bacterial infections among HIV-infected children with immune reconstitution who have discontinued opportunistic infection prophylaxis

OBJECTIVE

Receipt of highly active antiretroviral therapy is associated with a decrease in the incidence of opportunistic infections (OIs) among HIV-infected adults. The goal of Pediatric AIDS Clinical Trials Group protocol 1008 was to evaluate prospectively the incidence of serious bacterial infections (SBIs) and other OIs after discontinuation of OI and/or Pneumocystis jiroveci pneumonia (PCP) prophylaxis among HIV-infected pediatric subjects who experienced immune reconstitution while receiving stable antiretroviral therapy.

METHODS

HIV-infected children and adolescents, 2 to 21 years of age, who had received OI and/or PCP prophylaxis for > or =6 months were enrolled if they had sustained responses (>16 weeks before study entry) to antiretroviral therapy, with CD4+ cell percentages of > or =20% for patients >6 years of age or > or =25% for patients 2 to 6 years of age. Prophylaxis was discontinued at entry. To identify whether any correlation existed between functional immune reconstitution and protection from OIs, subjects were immunized with the hepatitis A virus vaccine. The association between the humoral immune response and the likelihood of developing an OI was evaluated.

RESULTS

A total of 235 HIV-infected subjects from 43 participating sites had a median follow-up period of 132 weeks, yielding 547 person-years of observation. Twenty SBIs were observed among 19 subjects, resulting in an incidence rate of 3.66 SBIs per 100 person-years (95% confidence interval: 2.24-5.66 SBIs per 100 person-years). Sixteen of the events were presumed bacterial pneumonia, with 4 proven SBIs. One participant experienced 2 separate pneumonia episodes, of presumed bacterial cause. Ten subjects who developed SBIs had baseline CD4+ cell counts of > or =750 cells per mm3, and 15 had CD4+ cell percentages of > or =25% at the time of their SBIs. Two subjects died as a result of non-SBI-related causes. There were no statistically significant differences in changes over time in CD4+ cell counts or CD4+ cell percentages between subjects who experienced primary end points and those who did not. There was no evidence that baseline protease inhibitor use, gender, race/ethnicity, age, or CD4+ cell count or percentage affected the time to development of a SBI.

CONCLUSIONS

OI or PCP prophylaxis can be withdrawn safely for HIV-infected pediatric patients who experience CD4+ cell recovery while receiving stable antiretroviral therapy. More studies are needed to assess the association between antibody responses to neoantigens and the development of SBIs.

An economic analysis of a pneumococcal vaccine programme in people aged over 64 years in a developed country setting

BACKGROUND

Polysaccharide pneumococcal vaccination for older adults is being introduced in developed country settings. Evidence of protection by this vaccine against pneumococcal pneumonia, or confirmation that illness and death from bacteraemia are prevented, is currently limited. Decisions are often made based on partial information. We examined the policy implications by exploring the potential economic benefit to society and the health sector of pneumococcal vaccination in older adults.

METHODS

A model to estimate the potential cost savings and cost-effectiveness of a polysaccharide pneumococcal vaccine programme was based on costs collected from patients, the literature, and routine health-services data. The effect of a pneumococcal vaccine (compared with no vaccination) was examined in a hypothetical cohort aged over 64 years. The duration of protection was assumed to be 10 years, with or without a booster at 5 years.

RESULTS

If it were effective against morbidity from pneumococcal pneumonia, the main burden from pneumococcal disease, the vaccine could be cost-neutral to society or the health sector at low efficacy (28 and 37.5%, respectively, without boosting and with 70% coverage). If it were effective against morbidity from bacteraemia only, the vaccine's efficacy would need to be 75 and 89%, respectively. If protection against both morbidity and mortality from pneumococcal bacteraemia was 50%, the net cost to society would be 2500 pounds per year of life saved ( 3365 pounds from the health-sector perspective). Results were sensitive to incidence, case-fatality rates, and costs of illness.

CONCLUSIONS

A vaccine with moderate efficacy against bacteraemic illness and death would be cost-effective. If it also protected against pneumonia, it would be cost-effective even if its efficacy were low.