Novel pneumococcal capsule type 33E results from the inactivation of glycosyltransferase WciE in vaccine type 33F.

The polysaccharide (PS) capsule is essential for immune evasion and virulence of Streptococcus pneumoniae. Existing pneumococcal vaccines are designed to elicit anticapsule antibodies; however, the effectiveness of these vaccines is being challenged by the emergence of new capsule types or variants. Herein, we characterize a newly discovered capsule type, 33E, that appears to have repeatedly emerged from vaccine type 33F via an inactivation mutation in the capsule glycosyltransferase gene, wciE. Structural analysis demonstrated that 33E and 33F share an identical repeat unit backbone [→5)-ß-D-Galf2Ac-(1→3)-ß-D-Galp-(1→3)-α-D-Galp-(1→3)-ß-D-Galf-(1→3)-ß-D-Glcp-(1→], except that a galactose (α-D-Galp) branch is present in 33F but not in 33E. Though the two capsule types were indistinguishable using conventional typing methods, the monoclonal antibody Hyp33FM1 selectively bound 33F but not 33E pneumococci. Further, we confirmed that wciE encodes a glycosyltransferase that catalyzes the addition of the branching α-D-Galp and that its inactivation in 33F strains results in the expression of the 33E capsule type. Though 33F and 33E share a structural and antigenic similarity, our pilot study suggested that immunization with a 23-valent pneumococcal PS vaccine containing 33F PS did not significantly elicit cross-opsonic antibodies to 33E. New conjugate vaccines that target capsule type 33F may not necessarily protect against 33E. Therefore, studies of new conjugate vaccines require knowledge of the newly identified capsule type 33E and reliable pneumococcal typing methods capable of distinguishing it from 33F.

Safety and Immunogenicity of a 20-valent Pneumococcal Conjugate Vaccine in Healthy Infants in the United States.

BACKGROUND: The development and widespread use of pneumococcal conjugate vaccines (PCVs) substantially reduced the global burden of pneumococcal disease. Expanding the serotypes covered by PCVs may further reduce disease burden. A 20-valent PCV (PCV20) has been developed to add coverage for 7 additional serotypes (8, 10A, 11A, 12F, 15B, 22F and 33F) to those in the existing 13-valent PCV (PCV13). This phase 2 study evaluated the safety, tolerability and immunogenicity of PCV20 in healthy US infants. METHODS: In this randomized, active-controlled, double-blind study, 460 infants were randomized 1:1 to receive a 4-dose series of either PCV20 or PCV13 at 2, 4, 6 and 12 months of age. Solicited local reactions and systemic events, adverse events (AEs) and serious AEs were recorded. Immunogenicity was assessed by measuring serotype-specific IgG concentrations and opsonophagocytic activity titers at 1 month after Dose 3, before Dose 4 and 1 month after Dose 4. RESULTS: Of 460 infants, 82.8% completed the 1-month visit after Dose 4. Local reactions and systemic events were mostly mild to moderate in severity and similar between the PCV20 and PCV13 groups. Treatment-related AEs were uncommon, with no related serious AEs or deaths reported. IgG and opsonophagocytic activity responses elicited by PCV20 were robust and demonstrated a booster response after Dose 4. CONCLUSIONS: Administration of PCV20 in US infants was well tolerated, with a safety profile similar to PCV13, and induced robust serotype-specific immune responses. These findings support continued development of PCV20 in the pediatric population.

Pneumococcal conjugate vaccine rollout in India: Expectations and challenges.

India is one among the four Asian countries with the greatest number of deaths due to pneumococcal infection among children under 5 years. pneumococcal conjugate vaccine (PCV) has been introduced in a phased manner in five major Indian states. Ambiguity remains in choosing the appropriate type of PCV and optimum schedule with maximum effectiveness specific for each country. Here, we discuss the evidences with respect to serotype coverage, immunogenicity, reactogenicity and dosage schedule for introduction of PCV13 in India. In addition, the expected PCV impact and the challenges are detailed. PCV13 is expected to provide >75% serotype coverage for invasive pneumococcal disease (IPD) serotypes in Indian children combined with the replacement by nonvaccine serotypes which is unpredictable due to lack of complete data. Nasopharyngeal (NP) surveillance is easy, feasible and can replace IPD surveillance in resource-poor settings. Continuous IPD as well as NP surveillance in all the regions are necessary to assess the impact of PCV in India.

Etiology of Bacterial Meningitis Among Children <5 Years Old in Côte d'Ivoire: Findings of Hospital-based Surveillance Before and After Pneumococcal Conjugate Vaccine Introduction.

BACKGROUND: Bacterial meningitis remains a major disease affecting children in Côte d'Ivoire. Thus, with support from the World Health Organization (WHO), Côte d'Ivoire has implemented pediatric bacterial meningitis (PBM) surveillance at 2 sentinel hospitals in Abidjan, targeting the main causes of PBM: Streptococcus pneumoniae (pneumococcus), Haemophilus influenzae, and Neisseria meningitidis (meningococcus). Herein we describe the epidemiological characteristics of PBM observed in Côte d'Ivoire during 2010-2016. METHODS: Cerebrospinal fluid (CSF) was collected from children aged <5 years admitted to the Abobo General Hospital or University Hospital Center Yopougon with suspected meningitis. Microbiology and polymerase chain reaction (PCR) techniques were used to detect the presence of pathogens in CSF. Where possible, serotyping/grouping was performed to determine the specific causative agents. RESULTS: Overall, 2762 cases of suspected meningitis were reported, with CSF from 39.2% (1083/2762) of patients analyzed at the WHO regional reference laboratory in The Gambia. In total, 82 (3.0% [82/2762]) CSF samples were positive for bacterial meningitis. Pneumococcus was the main pathogen responsible for PBM, accounting for 69.5% (52/82) of positive cases. Pneumococcal conjugate vaccine serotypes 5, 18C, 19F, and 6A/B were identified post-vaccine introduction. Emergence of H. influenzae nontypeable meningitis was observed after H. influenzae type b vaccine introduction. CONCLUSIONS: Despite widespread use and high coverage of conjugate vaccines, pneumococcal vaccine serotypes and H. influenzae type b remain associated with bacterial meningitis among children aged <5 years in Côte d'Ivoire. This reinforces the need for enhanced surveillance for vaccine-preventable diseases to determine the prevalence of bacterial meningitis and vaccine impact across the country.

Invasive Pneumococcal Disease in Children's Hospitals: 2014-2017.

BACKGROUND: The 13-valent pneumococcal conjugate vaccine (PCV13) was licensed in the United States in 2010. We describe invasive pneumococcal disease (IPD) in children at 8 children's hospitals in the US from 2014 to 2017. METHODS: Children with IPD occurring from 2014 to 2017 were identified from a prospective study. Demographic and clinical data, including results of any immune evaluation along with the number and dates of previous pneumococcal conjugate vaccines administered, were recorded on case report forms. Isolate serotypes were determined in a central laboratory. Pneumococcal conjugate vaccine doses were counted if IPD occurred ≥2 weeks after a dose. RESULTS: PCV13 serotypes accounted for 23.9% (115 out of 482) of IPD isolates from 2014 to 2017. Serotypes 3, 19A, and 19F accounted for 91% of PCV13 serotypes. The most common non-PCV13 serotypes were 35B, 23B, 33F, and 22F. An underlying condition was significantly (P < .0001) more common in children with IPD due to non-PCV13 serotypes (200 out of 367, 54.5%) than for children with PCV13 serotypes (27 out of 115, 23.5%). An immune evaluation was undertaken in 28 children who received ≥2 PCV13 doses before IPD caused by a PCV13 serotype. Only 1 was found to have an immunodeficiency. CONCLUSIONS: PCV13 serotypes (especially serotypes 3, 19A, and 19F) continue to account for nearly a quarter of IPD in US children 4 to 7 years after PCV13 was introduced. Underlying conditions are more common in children with non-PCV13 serotype IPD. Immune evaluations in otherwise healthy children with PCV13 serotype IPD despite receiving ≥2 PCV13 doses did not identify an immunodeficiency.

Genome-wide analysis of Streptococcus pneumoniae serogroup 19 in the decade after the introduction of pneumococcal conjugate vaccines in Australia.

The decline in invasive pneumococcal disease (IPD), following the introduction of the 7-valent pneumococcal conjugate vaccination (PCV-7), was tempered by emergence of non-vaccine serotypes, particularly 19A. In Australia, three years after PCV-7 was replaced by PCV-13, containing 19A and 19F antigens, serogroup 19 was still a prominent cause of IPD in children under five. In this study we examined the evolution of serogroup 19 before and after introduction of paediatric vaccines in New South Wales (NSW), Australia. Genomes of 124 serogroup 19 IPD isolates collected before (2004) and after introduction of PCV-7 (2008) and PCV-13 (2014), from children under five in NSW, were analysed. Eleven core genome sequence clusters (cgSC) and 35 multilocus sequence types (ST) were identified. The majority (78/124) of the isolates belonged to four cgSCs: cgSC7 (ST199), cgSC11 (ST320), cgSC8 (ST63) and cgSC9 (ST2345). ST63 and ST2345 were exclusively serotype 19A and accounted for its predominantly intermediate penicillin resistance; these two clusters first appeared in 2008 and largely disappeared after introduction of PCV-13. Serogroup 19 was responsible for the highest proportion of vaccine failures in NSW. Relatively low immunogenicity of serogroup 19 antigens and Australia's three-dose vaccine schedule could affect the population dynamics of this serogroup.

Compliance with the vaccination schedule in children hospitalized with pneumonia and associated factors.

OBJECTIVE: To verify the adequacy and factors associated with compliance with the immunization schedule (BCG, DTP-Hib, MMR, PCV-10) in children hospitalized with pneumonia at a pediatric referral hospital in Northeast Brazil. METHODS: This is a cross-sectional, descriptive study with an analytical component, with a sample of 452 children hospitalized with pneumonia at the Instituto de Medicina Integral Prof. Fernando Figueira, between 2010 and 2013. The inclusion criterion was children aged from one month to less than five years of age with proof in the immunization record. The exclusion criterion was the presence of hospital-acquired pneumonia or concomitant disease. We have evaluated the adequacy of the immunization schedule for the BCG, tetravalent, MMR, and 10-valent pneumococcal conjugate (PCV-10) vaccines. We used the chi-square test and Fisher's exact test followed by multivariate Poisson regression, estimating the crude and adjusted prevalence ratios and respective 95% confidence intervals. The variables with p < 0.20 in the univariate analysis were included in the multivariate analysis. RESULTS: There was good adequacy in the immunization schedule, except for PCV-10, which presented a percentage lower than 85%. We have observed an association between adequate compliance with the immunization schedule and education level of the mother (89.9% complete high school), sex of the child (87.2% female), age of the child (94.2% younger than six months), and breastfeeding (84.3% breastfed). CONCLUSIONS: Given the high rate of education level of the mother and the high percentage of breastfeeding, we can understand that there is a better understanding of the health of the child by the mothers studied in this study, showing the effectiveness of public policies for infant feeding. However, children did not have good adequacy of the immunization schedule of PCV-10, one of the main vaccines against pneumonia, which can be one of the main factors in the causes of hospitalization, with no influence on the classification of the severity of the disease. In this way, we emphasize that the causes of pneumonia morbidity are not associated with a single factor.

Compliance with the vaccination schedule in children hospitalized with pneumonia and associated factors / Cumprimento do esquema vacinal em crianças internadas por pneumonia e fatores associados

ABSTRACT OBJECTIVE: To verify the adequacy and factors associated with compliance with the immunization schedule (BCG, DTP-Hib, MMR, PCV-10) in children hospitalized with pneumonia at a pediatric referral hospital in Northeast Brazil. METHODS: This is a cross-sectional, descriptive study with an analytical component, with a sample of 452 children hospitalized with pneumonia at the Instituto de Medicina Integral Prof. Fernando Figueira, between 2010 and 2013. The inclusion criterion was children aged from one month to less than five years of age with proof in the immunization record. The exclusion criterion was the presence of hospital-acquired pneumonia or concomitant disease. We have evaluated the adequacy of the immunization schedule for the BCG, tetravalent, MMR, and 10-valent pneumococcal conjugate (PCV-10) vaccines. We used the chi-square test and Fisher's exact test followed by multivariate Poisson regression, estimating the crude and adjusted prevalence ratios and respective 95% confidence intervals. The variables with p < 0.20 in the univariate analysis were included in the multivariate analysis. RESULTS: There was good adequacy in the immunization schedule, except for PCV-10, which presented a percentage lower than 85%. We have observed an association between adequate compliance with the immunization schedule and education level of the mother (89.9% complete high school), sex of the child (87.2% female), age of the child (94.2% younger than six months), and breastfeeding (84.3% breastfed). CONCLUSIONS: Given the high rate of education level of the mother and the high percentage of breastfeeding, we can understand that there is a better understanding of the health of the child by the mothers studied in this study, showing the effectiveness of public policies for infant feeding. However, children did not have good adequacy of the immunization schedule of PCV-10, one of the main vaccines against pneumonia, which can be one of the main factors in the causes of hospitalization, with no influence on the classification of the severity of the disease. In this way, we emphasize that the causes of pneumonia morbidity are not associated with a single factor.

RESUMO OBJETIVO: Verificar a adequação e os fatores associados ao cumprimento do esquema vacinal (BCG, DTP-Hib, SCR, VCP-10) em crianças internadas com pneumonia em um hospital de referência pediátrica no Nordeste do Brasil. MÉTODOS: Estudo transversal, descritivo com componente analítico, composto por 452 crianças hospitalizadas por pneumonia no Instituto de Medicina Integral Prof. Fernando Figueira, entre 2010 e 2013. Critérios de inclusão: idade de um mês a menores de cinco anos; com comprovação do cartão vacinal. Critérios de exclusão: pneumonia hospitalar ou doença de base concomitante. Avaliamos a adequação do esquema vacinal da BCG, tetravalente, tríplice viral e pneumocócica conjugada 10 valente (VPC-10). Foram utilizados os testes qui-quadrado e exato de Fisher seguidos de regressão multivariada de Poisson, estimando-se as razões de prevalência brutas, ajustadas e os respectivos intervalos de confiança de 95%. Participaram da análise multivariada as variáveis que na análise univariada apresentaram valor p < 0,20. RESULTADOS: Houve boa adequação no calendário vacinal, exceto a vacina VPC-10, que apresentou percentual inferior a 85%. Observou-se associação entre o adequado cumprimento do esquema vacinal e escolaridade materna (89,9% ensino médio completo), sexo da criança (87,2% feminino), idade da criança (94,2% menor que seis meses) e aleitamento materno (84,3% amamentaram). CONCLUSÕES: Pela elevada taxa na escolaridade materna e pelo elevado percentual de alimentação por leite materno, pode-se entender que há uma melhor compreensão no cuidado da saúde da criança pelas genitoras estudadas nesta pesquisa, apresentando a eficácia das políticas públicas de alimentação infantil. Porém, as crianças não tiveram uma boa adequação do esquema vacinal da VPC-10, uma das principais vacinas contra a pneumonia, podendo ser esse um dos principais fatores nas causas do internamento, não apresentando influência com a classificação da gravidade da doença. Enfatiza-se dessa maneira que as causas de morbidade por pneumonia não são associadas a um único fator.

Key features of invasive pneumococcal isolates recovered in Lima, Peru determined through whole genome sequencing.

Before PCV7 introduction, invasive pneumococcal disease (IPD) was responsible for approximately 12,000-18,000 deaths annually among children <5years in Latin America. In Peru, PCV7 was introduced in 2009. We used whole genome sequencing to deduce key features of invasive strains collected in Lima, Peru from 2006 to 2011. We sequenced 212 IPD isolates from 16 hospitals in Lima pre (2006-2009; n=133) and post (2010-2011; n=79) PCV7 introduction; 130 (61.3%) isolates were from children≤5years old. CDC's Streptococcus lab bioinformatics pipeline revealed serotypes, sequence types (STs), pilus genes, PBP types and other resistance determinants. During the pre-PCV7 period, serotype 14 was the most common serotype (24.8%), followed by 6B (20.3%), 19F (10.5%), and 23F (6.8%). Post-PCV7, the proportion of PCV7 serotype 6B decreased significantly (to 6.3%), while 19F (16.3%), 14 (15.0%), 23F (7.5%), and 19A (7.5%) were the most common serotypes; only serotypes 3 and 10A increased significantly. Overall, 82% (n=173) of all isolates carried at least one resistance determinant, including 72 (34%) isolates that carried resistance determinants against 3 or more antimicrobial classes; of these 72 isolates, 56 (78%) belonged to a PCV7 serotype. Eighty-two STs were identified, with 53 of them organized in 14 clonal complexes. ST frequencies were distributed differently pre and post-PCV7 introduction, with only 18 of the 57 STs identified in years 2006-2009 isolates also observed in years 2010-2011 isolates. The apparent expansion of a 19F/ST1421 lineage with predicted ß-lactam resistance (PBP type 13:16:20) and carrying resistance determinants against four additional antimicrobial classes was observed.

Colonization with 19F and other pneumococcal conjugate vaccine serotypes in children in St. Louis, Missouri, USA.

BACKGROUND: The epidemiology of nasopharyngeal (NP) pneumococcal carriage varies with geography and has changed in response to pneumococcal conjugate vaccine (PCV): a low prevalence (3% or less of colonizing isolates) of colonization by vaccine-type (VT) pneumococcal serotypes after PCV introduction has been reported. The primary goal of this study was to determine the VT serotype prevalence of NP pneumococcal colonization of children residing in the St. Louis, MO, USA metropolitan area following introduction of the 13-valent PCV in 2010. The secondary goal of this study was to identify characteristics associated with NP pneumococcal carriage of any serotype. METHODS: Between July 2013 and April 2016, we enrolled 397 healthy children, aged 0-17years, who required sedation for procedures or minor surgeries at St. Louis Children's Hospital. NP swabs were collected after sedation or anesthesia and cultured for pneumococcus. Vaccine records were obtained from primary care providers or from state immunization databases. Parents/guardians completed a questionnaire to provide demographics, past medical history and household characteristics. RESULTS: Of the 88 pneumococcal isolates recovered from 84 colonized subjects (21.2% of all enrolled subjects; 95% CI 17.2-25.2%), 16 were VT. Eleven isolates were serotype 19F (12.5%), four (4.5%) were 6A and one (1.1%) was 19A. Prevalence of VT among colonizing isolates was thus 18.2% (CI 10.1-26.1%) in our cohort, despite complete PCV vaccination in 87% of colonized children. Factors associated with pneumococcal colonization by any serotype included younger age and daycare attendance. CONCLUSION: Children in St. Louis exhibit a higher prevalence of VT serotypes among pneumococcal carriage isolates than has been reported in other areas in the US, demonstrating the necessity of ongoing surveillance of local epidemiology and providing evidence that serotype 19F can remain prevalent in a pediatric population despite high vaccine uptake.

Invasive pneumococcal disease in Australia, 2011 and 2012.

In Australia, there were 1,883 cases (8.3 per 100,000 population) of invasive pneumococcal disease (IPD) notified to the National Notifiable Diseases Surveillance System (NNDSS) in 2011 and 1,823 cases (8.0 per 100,000) in 2012. The overall rate of IPD in Indigenous Australians was 9 times the rate of IPD in non-Indigenous Australians in 2011 and 7 times in 2012. Following the July 2011 introduction of the 13-valent pneumococcal conjugate vaccine (13vPCV) to the National Immunisation Program, rates of IPD in children aged less than 5 years decreased from 19.5 per 100,000 in 2011 to 12.6 per 100,000 in 2012. In Indigenous adults aged 50 years or over the rates of IPD caused by serotypes included in the 23-valent pneumococcal polysaccharide vaccine (23vPPV) continued to increase in both 2011 (47.2 per 100,000) and 2012 (51.2 per 100,000). The rates of IPD in non-Indigenous adults aged 65 years or over caused by serotypes included in the 23vPPV also increased in 2011 (10.1 per 100,000) and 2012 (11.2 per 100,000). There were 134 deaths attributable to IPD in 2011 and 126 in 2012, although it should be noted that deaths may be under-reported. The number of invasive pneumococcal isolates with reduced penicillin susceptibility remained low and reduced susceptibility to ceftriaxone/cefotaxime continued to be rare.

Acute bacterial meningitis in adults.

Over the past several decades, the incidence of bacterial meningitis in children has decreased but there remains a significant burden of disease in adults, with a mortality of up to 30%. Although the pathogenesis of bacterial meningitis is not completely understood, knowledge of bacterial invasion and entry into the CNS is improving. Clinical features alone cannot determine whether meningitis is present and analysis of cerebrospinal fluid is essential for diagnosis. Newer technologies, such as multiplex PCR, and novel diagnostic platforms that incorporate proteomics and genetic sequencing, might help provide a quicker and more accurate diagnosis. Even with appropriate antimicrobial therapy, mortality is high and so attention has focused on adjunctive therapies; adjunctive corticosteroids are beneficial in certain circumstances. Any further improvements in outcome are likely to come from either modulation of the host response or novel approaches to therapy, rather than new antibiotics. Ultimately, the best hope to reduce the disease burden is with broadly protective vaccines.

Direct molecular detection of a broad range of bacterial and viral organisms and Streptococcus pneumoniae vaccine serotypes in children with otitis media with effusion.

BACKGROUND: Otitis media with effusion (OME) causes significant morbidity in children, but the causes of OME and methods for prevention are unclear. To look for potential infectious etiologies, we performed a pilot study using multiple-target real-time polymerase chain reaction (qPCR) for 27 infectious agents, including nine bacterial organisms and 18 respiratory viruses in middle ear fluids (MEFs) from children with OME. QPCR was also performed for the 13 Streptococcus pneumoniae serotypes contained in the current vaccine. RESULTS: Forty-eight MEF samples were obtained and qPCR detected bacterial nucleic acid (NA) in 39/48 (81%) and viral NA in 7/48 (15%). Alloiococcus otitidis and S. pneumoniae were both detected in 15/48 (31%) MEFs, followed by M. catarrhalis in 14/48 (29%), H. influenzae in 5/48 (10%) and M. pneumoniae in 4/48 (8%). Rhinoviruses were most common virus type detected, found in 4/48 (8%) MEFs. Serotypes included in the current 13-serotype vaccine were detected in only 3/15 (20%) S. pneumoniae qPCR-positive MEFs. CONCLUSIONS: Bacteria may play an important role in OME, since over 80% of MEFs contained bacterial NA. Further research into the role of A. otitidis in OME will be helpful. Serotypes of S. pneumoniae not included in the current 13-serotype vaccine may be involved in OME. Larger studies of OME S. pneumoniae serotypes are needed to help determine which additional serotypes should be included in future vaccine formulations in order to try to prevent OME.

[Pneumococcal vaccination for prevention of pneumonia]. / Pneumonieprävention durch Pneumokokkenimpfung.

Aging of the immune system, so-called immunosenescence, is well documented as the cause of increased infection rates and severe, often complicated courses of infections in older adults. This is particularly true for pneumococcal pneumonia in older adults; therefore, the standing committee on vaccination of the Robert Koch Institute (STIKO) recommends a once only vaccination with 23-valent pneumococcal polysaccharide vaccine for all persons aged 60 years and over. Furthermore, the 13-valent pneumococcal conjugate vaccine is also available for administration in adults and is recommended by the STIKO for particular indications. The advantage of the pneumococcal conjugate vaccine is the additional induction of a T-cell dependent immune response that leads to good immunogenicity despite immunosenescence. Initial data from a recent randomized controlled trial, so far only presented at conferences, confirm that the conjugate vaccine also provides protection against non-bacteremic pneumococcal pneumonia, which is not provided by the polysaccharide vaccine. Thus, there are two vaccines for prevention of pneumococcal diseases: one with a broader range of serotype coverage but with an uncertain protection against non-bacteremic pneumococcal pneumonia and another one with less serotype coverage but more effective protection. Vaccination of children with the conjugate vaccine also leads to a rapid decrease of infections by the 13 vaccine serotypes even in adults because of herd protection effects. For prevention of pneumonia in older adults the additional benefit of a concurrent application of influenza vaccine and pneumococcal vaccine should be considered.

[Pneumococcal vaccines: different types and their use in practice]. / Vaccins anti-pneumococciques: explication des différentes sortes de vaccins et de leur utilisation dans la pratique.

Streptococcus pneumoniae is responsible for a large number of invasive infections and upper respiratory tract infections in infants, elderly and patients with high complication risk. Currently, two types of vaccine are available on the Belgian market. In the context of pharmaceutical care, it is important for pharmacists to know their specific characteristics and differences. In this article we try to explain these and to motivate their use in different patient populations. The 23-valent vaccine is different from the 13-valent vaccine, not only in number of serotypes, but also in its presentation as respectively polysaccharide- and conjugated vaccine which affects the immunogenicity. Moreover, their indication and use are also different. Finally we take a closer look at the specific use in infants and children at risk at one hand, and vaccination of eldery and adults with increased risk for severe pneumococcal infection on the other hand.

Multiplex PCR reveals a high rate of nasopharyngeal pneumococcal 7-valent conjugate vaccine serotypes co-colonizing indigenous Warao children in Venezuela.

Knowledge of co-colonization with multiple pneumococcal serotypes is becoming very important in the light of both serotype replacement and switching as a result of vaccination. Co-colonization has been reported to occur in up to 30% of carriers, especially in populations with high Streptococcus pneumoniae carriage rates. For the determination of co-colonization, single colonies of nasopharyngeal specimens are serotyped with the Quellung method, a costly method with a low sensitivity. Here we explore the use of a multiplex PCR to identify simultaneous carriage of the capsular serotypes targeted by the 7-valent conjugate vaccine. We applied this multiplex PCR to 50 primary cultures from the nasopharyngeal swabs of healthy Warao Amerindian children, a population with a high pneumococcal carriage rate, most of them with vaccine serotypes, and we identified a second serotype in 20% (n=10) of the pneumococci carriers. These results were confirmed by detailed serotyping of multiple colonies isolated from the primary culture with the Quellung method. We conclude that the multiplex PCR is a sensitive, simple and cost-effective method for detecting multiple serotypes in nasopharyngeal cultures, and thus might be useful for the monitoring of pneumococcal colonization over time, especially in the surveillance of nasopharyngeal colonization after conjugate vaccination.

Hyposplenism: a comprehensive review. Part I: basic concepts and causes.

Hyposplenism is not a rare condition and can complicate a remarkable number of illnesses. The two most time-honored diseases associated with the development of hyposplenism are sickle cell anemia and celiac disease. Hyposplenism is relatively easy to recognize by typical changes observed on the peripheral blood smear; including Howell-Jolly bodies, monocytosis, lymphocytosis, and increased platelet counts. Diagnosis can be confirmed by pitted RBC counts or 99Tc-labelled radiocolloid scan of the spleen; wherever available. Diagnosis needs to be made promptly to institute pneumococcal vaccination in a timely fashion and to recognize and treat bacterial infections promptly and aggressively because of the tendency of hyposplenic subject to develop fatal invasive disease. Overwhelming pneumococcal sepsis accounts for the major mortality cases in hyposplenic subjects; however severe infections with other encapsulated bacteria and protozoa have been reported. Hyposplenic individuals may also be at a higher risk for vascular, autoimmune and thrombotic diseases and they may have a higher risk of developing solid tumors. The commonly used pneumococcal polysaccharide vaccine is ineffective in asplenic subjects, because it requires the presence of IgM memory B cells, and should be given before splenectomy. In splenectomized, and functionally hyposplenic subjects, the pneumococcal conjugate vaccine is more effective, because it utilizes a T cell dependent mechanism, and should be the preferred vaccine in these circumstances.

Development of a DNA microarray to identify the Streptococcus pneumoniae serotypes contained in the 23-valent pneumococcal polysaccharide vaccine and closely related serotypes.

Streptococcus pneumoniae is a major worldwide human pathogen. This investigation has developed a reliable and accurate DNA microarray method for inter-species differentiation of S. pneumoniae and intra-species differentiation of the 23 groups of S. pneumoniae including serotypes represented in the 23-valent pneumococcal vaccine and the other 20 closely related serotypes. In addition to 16S rDNA probes, serotype- or serogroup-specific probes targeting the capsular polysaccharide synthesis (cps) genes, wzy or capA were generated. We adopted a two-step multiplex PCR to improve the sensitivity of detection to a level of 10(5) cfu/ml in pure culture or 50 ng DNA. A total of 169 isolates (from China, Australia, Canada and New Zealand) including 147 belonging to 23-valent vaccine and closely related serotypes of S. pneumoniae, 11 belonging to other serotypes and 11 of different species commonly isolated from respiratory tract were tested to verify the method. The DNA microarray method developed provides a sensitive means to rapidly identify the members of the most common S. pneumoniae serotypes in patients and to monitor their distribution in different patient groups and geographic locations. Such information is needed for disease surveillance and to monitor vaccine efficacy.