13-valent Conjugate Vaccine Research Articles

Serotipos de neumococo en nasofaringe de niños preescolares sanos tras la vacunación antineumocócica conjugada heptavalente

Background and objective To determine the characteristics influencing pneumococcal serotype colonization in healthy pre-school aged children, the distribution of serotypes and their antimicrobial susceptibility, after the introduction of pneumococcal 7-valent conjugate vaccine (VNC-7 v). Sujetos and methods Nasopharyngeal samples were collected from children under 6 years of age attending well-child examinations in the province of Zaragoza (Spain). Logistic regression was used to study different variables related to the status of the carriers. Results Of the 371 children studied 30.7% were found to be carriers. With a vaccine coverage rate of 66%, factors related with presence of pneumococcal carriage were found to be the number of siblings (OR 1.44; CI 95% 1.05-1.97 for each sibling), attending a school or child day care centre (OR 3.99; CI 95% 2.00-7.96) and suffering from a minor upper respiratory tract infection (URTI) (OR 1.72; CI 95% 1.02-2.90). Only 8.7% corresponded to VNC-7 v serotypes. The most common non VNC-7 v serotypes isolated were 19A, 6A, 15B, 11, and 15A. Significantly greater resistance was detected among VNC-7 v serotypes. Conclusion Children in the setting of this study carried pneumococci more commonly when they have siblings, attend school or day care, or suffer from minor URTI. In the VNC-7 v vaccine era, VNC-7 v serotypes have become rare occurrences (8.7%) and emerging serotypes present better susceptibility to antibiotics.

Detection of Streptococcus pneumoniae and Identification of Pneumococcal Serotypes by Real-Time Polymerase Chain Reaction Using Blood Samples from Italian Children ≤5 Years of Age with Community-Acquired Pneumonia

Streptococcus pneumoniae is a leading cause of severe life-threatening infections. Laboratory identification and serotyping of this pathogens is desirable to monitor vaccine impact and coverage; however, especially in pediatric patients, the yield of traditional microbiological diagnostic procedures can be very low. The aim of this study was to develop real-time polymerase chain reaction (PCR)-based assays to be performed directly on blood samples to identify the most common capsular serotypes causing pneumonia in Italian children (≤ 5 years of ages) after the introduction of the 7-valent conjugate vaccine. Our real-time PCR-based assays showed high sensitivity (at least 35 fg of pneumococcal DNA), and they were validated with 49 well-characterized pneumococcal isolates, 8 nonpneumococcal isolates, 13 simulated blood clinical samples loaded with S. pneumoniae of known serotypes, and 46 blood clinical samples. All the strains tested and the simulated blood clinical samples were correctly typed by the technique. Real-time PCR allowed serotyping in 37/46 children ≤ 5 years of age (80.4%) in whom pneumonia was diagnosed in four Italian hospitals. Non-PCV7 serotypes accounted for at least 47.8% (22/46) of cases, serotype 19A being the most common (34.7%, 16/46). Although, it is not known at present whether the incidence of 19A serotype is attributable to the use of PCV7 only, expanding pneumococcal serotype coverage has clearly the potential to prevent a larger number of pneumonias in Italian children less than ≤ 5 years of age. Molecular methods are of increasing importance in the diagnosis of pneumococcal pneumonia and in monitoring serotype distribution and replacement.

First Report of Streptococcus pneumoniae Serotype 6D in South America

Streptococcus pneumoniae includes the two serotypes 6A and 6B as well as two recently discovered serotypes, 6C and 6D, in which the wciNα gene is replaced by wciNβ within the cps locus. Serotype 6D occurrence in Asia (2, 4), the Fiji islands (5) and Europe (7, 9) has recently been reported. To our knowledge, we describe here the first description of serotype 6D isolates identified within the Americas. Using the CDC serogroup 6 serotyping scheme (8), we identified 155 serogroup 6 isolates within a larger collection (n = 693) taken from nasopharyngeal carriage in children <2 years old in Peru (2007 to 2009; 541 strains) (unpublished data) and invasive pneumococcal disease (IPD) surveillance in children in Lima hospitals (2006 to 2009; 152 strains) (reference 10 and unpublished data). Among the 155 serogroup 6 isolates, 26, 105, and 22 isolates were identified as serotypes, 6A, 6B, and 6C, respectively (Table 1). We tentatively identified two 6D isolates on the basis of positive reactions with factor sera for serotype 6B (factor 6c) and serotype 6C (factor 6d) and a negative reaction with factor serum for serotype 6A (factor 6b). We verified the serologic results for all 155 serogroup 6 isolates using a recently developed PCR scheme that efficiently resolves all four serogroup 6 serotypes (6). This scheme discriminates between serotypes 6A/6C and 6B/6D using wciP allele-specific reactions. The presence or absence of wciNβ determined by a second reaction subsequently allowed resolution into all four serotypes (Table 1). Table 1. Quellung and PCR results for 155 serogroup 6 isolates The two 6D isolates, both from carriage, shared the new multilocus sequence typing (MLST) profile ST6148 (ST6148, 8-8-263-12-6-104-14) and were both fully susceptible to a variety of antimicrobial agents by broth microdilution. ST6148 is unrelated to previously described 6D genotypes on the MLST website (http://spneumoniae.mlst.net/, last accessed on 5 January 2011). It is, however, highly related to serotype 6A and 6B isolates both from carriage and invasive disease that were characterized from this same study, differing only at the recP allele. These data, together with data published elsewhere, show identical or related multilocus sequence types shared between serotype 6C or 6D strains containing wciNβ and 6A or 6B strains that contain wciNα (3, 4, 7). This suggests that the two different wciN genes are frequently horizontally transferred between different serogroup 6 strains in nature to effect intraserogroup 6 capsular switch events. On the basis of these genotype observations it also circumstantially appears likely that in some cases wciP is cotransferred with wciN, which could effect, for example, a serotype 6A to serotype 6D capsular switch. In summary, we believe that this is the first reported detection of serotype 6D among pneumococcal isolates recovered in South America or elsewhere in the western hemisphere, despite the fact that our U.S.-based surveillance has been vigilant for its appearance using serologic and PCR-based approaches for 6D detection (3, 8). The work presented here validates serotype 6D as the 92nd serotype identifiable by using CDC pneumococcal typing sera (Table 1). Serotype 6C was not effectively targeted by the pneumococcal 7-valent conjugate vaccine according to recent IPD surveillance data (3); however, there are no existing comparable data for serotype 6D. It is hoped that the recently implemented 13-valent conjugate vaccine (1) will effectively target all serogroup 6 pneumococcal diseases.

A multiplex polymerase chain reaction method for rapid pneumococcal serotype determination in childhood empyema

Nonvaccine serotypes are increasingly responsible for pneumococcal empyema. We developed a one-step polymerase chain reaction for identifying all serotypes covered by the 13-valent conjugate vaccine. Over 1 year, we identified serotypes 19A ( n = 6), 1 ( n = 2), 3 ( n = 1) and 7F/A ( n = 2), both in culture-positive and culture-negative pleural fluid from 11 children with empyema.

Evolution of Clonal and Susceptibility Profiles of Serotype 19A Streptococcus pneumoniae among Invasive Isolates from Children in Spain, 1990 to 2008

The genetic structure and antibiotic nonsusceptibility of all serotype 19A Streptococcus pneumoniae pediatric pneumococcal isolates received at the Spanish Pneumococcal Reference Laboratory (1990 to 2008) were analyzed. Of them, 410 (79.8%) isolates belonged to 14 sequence types (STs) with >10 isolates each, and 104 to 73 STs (with 21 new STs, ST5141 to ST5161, with one isolate each). Time trends in 2000 to 2008 (n=471) were explored by lineal regression. Serotype 19A increased from 5.7% in 2000 to 16.8% in 2008 (R2=0.872; P=0.001). Decreasing trends (P<0.03) were found for ST202 (R2=0.774) and ST81 (R2=0.559), and increasing trends (P<0.03) for ST878 (R2=0.544) and ST320 (R2=0.530), both belonging to the clonal complex (CC) Denmark(14)-32 and first detected in 2003 and 2007, respectively, and ST2013 (R2=0.704) and ST4461 (R2=0.707), both appearing in 2004. Penicillin nonsusceptibility was clustered in ST81, ST276, ST320, ST878, ST2013, and ST4461 (>90% nonsusceptibility), and amoxicillin and cefotaxime nonsusceptibility in ST320: 87% amoxicillin (MIC50/MIC90=8/8 μg/ml) and 43.5% cefotaxime (MIC50/MIC90=1/2 μg/ml) nonsusceptibility. No trends were found for erythromycin nonsusceptibility (ranging from 38.5% to 66.7%) and cefotaxime nonsusceptibility (ranging from 0.0% to 7.8%), but increasing trends (P<0.02) were found for oral penicillin (from 16.7% in 2000 to 56.3% in 2008; R2=0.628) and amoxicillin (from 0.0% before 2007 to 13.8% in 2008; R2=0.628) nonsusceptibility. This study warns about the emergence of serotype 19A STs associated with high-level antibiotic nonsusceptibility, with a role for ST320 and ST878 occupying the niche left by some pneumococcal 7-valent conjugate vaccine (PCV7)-related resistant STs. The rapid expansion of serotype 19A and STs related to antibiotic resistance indicates that vaccines covering serotype 19A present advantages in countering invasive disease.

Analysis of invasive pneumonia-causing strains of Streptococcus pneumoniae: serotypes and antimicrobial susceptibility

To identify the most common pneumococcal serotypes in children hospitalized with invasive pneumonia, correlate isolated serotypes with those included in conjugate vaccines, and ascertain the sensitivity of the isolated pneumococcal strains to penicillin and other antibiotics. From January 2003 to October 2008, a retrospective study of hospitalized children with a diagnosis of Streptococcus pneumoniae pneumonia was conducted at the university hospital of Universidade de São Paulo. Criteria for inclusion were: age greater than 29 days and less than 15 years, radiological and clinical diagnosis of pneumonia, and isolation of Streptococcus pneumoniae in blood cultures and/or pleural effusion. The study included 107 children. The most common serotypes were 14 (36.5%), 1 (16%), 5 (14.6%), 6B (6.3%) and 3 (4.2%). The proportion of identified serotypes contained in the heptavalent, 10-valent and 13-valent conjugate vaccines was 53.1, 86.5, and 96.9%, respectively. Pneumococcal strains were sensitive to penicillin (minimum inhibitory concentration, MIC ≤ 2 µg/mL) in 100 cases (93.5%) and displayed intermediate resistance (MIC = 4 µg/mL) in 7 cases (6.5%). No strains were penicillin-resistant (MIC ≥ 8 µg/mL) according to the Clinical and Laboratory Standards Institute 2008 standards. Tested isolates were highly sensitive to vancomycin, rifampicin, ceftriaxone, clindamycin, erythromycin, and chloramphenicol. Our results confirm a significant potential impact of conjugate vaccines, mainly 10-valent and 13-valent, on invasive pneumonia. Furthermore, susceptibility testing results show that penicillin is still the treatment of choice for invasive pneumonia in our setting.

Análise das cepas de Streptococcus pneumoniae causadores de pneumonia invasiva: sorotipos e sensibilidade aos antimicrobianos

OBJECTIVES: To identify the most common pneumococcal serotypes in children hospitalized with invasive pneumonia, correlate isolated serotypes with those included in conjugate vaccines, and ascertain the sensitivity of the isolated pneumococcal strains to penicillin and other antibiotics. METHODS: From January 2003 to October 2008, a retrospective study of hospitalized children with a diagnosis of Streptococcus pneumoniae pneumonia was conducted at the university hospital of Universidade de Sao Paulo. Criteria for inclusion were: age greater than 29 days and less than 15 years, radiological and clinical diagnosis of pneumonia, and isolation of Streptococcus pneumoniae in blood cultures and/or pleural effusion. RESULTS: The study included 107 children. The most common serotypes were 14 (36.5%), 1 (16%), 5 (14.6%), 6B (6.3%) and 3 (4.2%). The proportion of identified serotypes contained in the heptavalent, 10-valent and 13-valent conjugate vaccines was 53.1, 86.5, and 96.9%, respectively. Pneumococcal strains were sensitive to penicillin (minimum inhibitory concentration, MIC 8 µg/mL) according to the Clinical and Laboratory Standards Institute 2008 standards. Tested isolates were highly sensitive to vancomycin, rifampicin, ceftriaxone, clindamycin, erythromycin, and chloramphenicol. CONCLUSIONS: Our results confirm a significant potential impact of conjugate vaccines, mainly 10-valent and 13-valent, on invasive pneumonia. Furthermore, susceptibility testing results show that penicillin is still the treatment of choice for invasive pneumonia in our setting.

Pneumococcal serotype distribution and antimicrobial resistance in Chinese children hospitalized for pneumonia

A prospective study was performed to determine serotype distribution and antimicrobial resistance in Streptococcus pneumoniae ( S. pneumoniae) from Chinese children <5 years old meeting pneumonia criteria. A total of 3865 children were enrolled and 338 S. pneumoniae isolates were obtained. The most frequent serotypes were 19F (55.6%), 19A (13.9%), 23F (10.1%), 6B (4.7%), and 14 (3.6%). The 7-, 10- and 13-valent conjugate vaccines, respectively, covered 76.3%, 76.9%, and 92.3% of isolates. Out of the isolates, six (1.8%) were penicillin resistant. All except 1 of the isolates were resistant to erythromycin. Serotype 19A showed the highest drug resistance. The use of PCV7 has the potential to prevent a substantial number of pneumococcal infections. However, PCV13 is likely to prevent more episodes of pneumococcal disease in China because of the high rates of 19A.

Streptococcus pneumoniae meningitis in Alberta pre- and postintroduction of the 7-valent pneumococcal conjugate vaccine.

To describe the epidemiology, clinical characteristics, microbiology and outcomes of patients of all ages with Streptococcus pneumoniae meningitis two years pre- and postintroduction of a S pneumoniae 7-valent conjugate vaccine program in Alberta in children <2 years of age. Between 2000 and 2004, all cases of invasive pneumococcal disease in Alberta were identified. From this cohort, patients with S pneumoniae meningitis were identified by chart review. Clinical data, laboratory data and in-hospital outcomes were collected. Of the 1768 cases of invasive pneumococcal disease identified between 2000 and 2004, 110 (6.2%) had S pneumoniae meningitis. The overall incidence was 0.7 per 100,000 persons and remained unchanged over the study period. The rate in children <2 years of age appeared to fall over time, from 10.5 per 100,000 persons in 2000 to five per 100,000 persons in 2004, although there was insufficient evidence of a statistically significant time trend within any age group. Overall, the mean age was 30 years and 47% were male. In-hospital mortality was 20%, ranging from 6% in those ≤2 years of age to 31% for those ≥18 years of age, despite appropriate antimicrobial therapy. The high mortality rate associated with S pneumoniae meningitis suggests that prevention by vaccination is critical. In children <2 years of age, there was a downward trend in the rate of S pneumoniae meningitis after implementation of the S pneumoniae 7-valent conjugate vaccine program, but rates were still high.

Serotype distribution and antimicrobial resistance of Streptococcus pneumoniae prior to introduction of the 10-valent pneumococcal conjugate vaccine in Brazil, 2000–2007

This study describes the serotype distribution and antibiotic resistance patterns among 397 S. pneumoniae meningitis case isolates recovered in Salvador, Brazil, during the period of 2000–2007, before introduction of the 10-valent pneumococcal conjugate vaccine.The active hospital-based surveillance showed a decline in the annual incidence rates of pneumococcal meningitis during the period of study, from 1.12 cases to 0.83 cases/100,000 persons for all age groups (P<0.001), with an overall case-fatality rate of 28.6% (113 of 395) for all patients and 41.9% (57 of 136) for those <5 years of age. Serotypes 14 (n=55; 13.9%), 3 (n=32; 8.1%), 23F (n=32; 8.1%), 19F (n=31; 7.8%), 6B (n=30; 7.6%), 18C (n=28; 7.1%), and 6A (n=20; 5%) were the most prevalent serotypes. In patients <5 years the estimated projected coverage of 7-, 10- and 13-valent conjugate vaccines was 74.3%, 75.7% and 83.1%, respectively. Antimicrobial susceptibility testing revealed that 22.1% (n=88) of isolates were non-susceptible to penicillin, 56% were non-susceptible to trimethoprim/sulphamethoxazole, and 29.6% were non-susceptible to tetracycline. Nonsusceptibility to penicillin and cefotaxime was detected solely among serotype 14 isolates (n=4; 1%). This study provides an important baseline to assess the impact of conjugate vaccine implantation on the epidemiology of meningitis due to Streptococcus pneumoniae in Salvador, Brazil.

Relationship between Serotypes, Age, and Clinical Presentation of Invasive Pneumococcal Disease in Madrid, Spain, after Introduction of the 7-Valent Pneumococcal Conjugate Vaccine into the Vaccination Calendar

To assess invasive pneumococcal disease (IPD) clinical presentations and relationships with age and serotype in hospitalized children (<15 years) after PCV7 implementation in Madrid, Spain, a prospective 2-year (May 2007 to April 2009) laboratory-confirmed (culture and/or PCR) IPD surveillance study was performed (22 hospitals). All isolates (for serotyping) and culture-negative pleural/cerebrospinal fluids were sent to the reference laboratory for pneumolysin (ply) and autolysin (lyt) gene PCR analysis. A total of 330 IPDs were identified: 263 (79.7%) confirmed by culture and 67 (20.3%) confirmed by PCR. IPD distribution by age (months) was as follows: 23.6% (<12), 15.8% (12 to 23), 15.5% (24 to 35), 22.4% (36 to 59), and 22.7% (>59). Distribution by clinical presentation was as follows: 34.5% bacteremic pneumonia, 30.3% pediatric parapneumonic empyema (PPE), 13.6% meningitis, 13.3% primary bacteremia, and 8.2% others. Meningitis and primary bacteremia were the most frequent IPDs in children <12 months old, and bacteremic pneumonia and PPE were most frequent in those >36 months old. Frequencies of IPD-associated serotypes were as follows: 1, 26.1%; 19A, 18.8%; 5, 15.5%; 7F, 8.5%; 3, 3.9%; nontypeable/other 30 serotypes, 27.3%. Serotype 1 was linked to respiratory-associated IPD (38.6% in bacteremic pneumonia and 38.0% in PPE) and children of >36 months (51.4% for 36 to 59 months and 40.0% for >59 months), while serotype 19A was linked to nonrespiratory IPDs (31.1% in meningitis, 27.3% in primary bacteremia, and 51.9% in others) and children of <24 months (35.9% for children of <12 months and 36.5% for those 12 to 23 months old), with high nonsusceptibility rates for penicillin, cefotaxime, and erythromycin. After PCV7 implementation, non-PCV7 serotypes caused 95.5% of IPDs. The new 13-valent conjugate vaccine would provide 79.1% coverage of serotypes responsible for IPDs in this series.

Continued control of pneumococcal disease in the UK – the impact of vaccination

Streptococcus pneumoniae, also known as the pneumococcus, is an important cause of morbidity and mortality in the developed and developing world. Pneumococcal conjugate vaccines were first introduced for routine use in the USA in 2000, although the seven-valent pneumococcal conjugate vaccine (PCV7) was not introduced into the UK's routine childhood immunization programme until September 2006. After its introduction, a marked decrease in the incidence of pneumococcal disease was observed, both in the vaccinated and unvaccinated UK populations. However, pneumococci are highly diverse and serotype prevalence is dynamic. Conversely, PCV7 targets only a limited number of capsular types, which appears to confer a limited lifespan to the observed beneficial effects. Shifts in serotype distribution have been detected for both non-invasive and invasive disease reported since PCV7 introduction, both in the UK and elsewhere. The pneumococcal Haemophilus influenzae protein D conjugate vaccine (PHiD-CV, Synflorix; GlaxoSmithKline) and 13-valent pneumococcal conjugate vaccine (PCV13, Prevenar 13; Pfizer) have been newly licensed. The potential coverage of the 10- and 13-valent conjugate vaccines has also altered alongside serotype shifts. Nonetheless, the mechanism of how PCV7 has influenced serotype shift is not clear-cut as the epidemiology of serotype prevalence is complex. Other factors also influence prevalence and incidence of pneumococcal carriage and disease, such as pneumococcal diversity, levels of antibiotic use and the presence of risk groups. Continued surveillance and identification of factors influencing serotype distribution are essential to allow rational vaccine design, implementation and continued effective control of pneumococcal disease.

Developing the Right Pneumococcal Vaccine for the Time and Place

Developing the Right Pneumococcal Vaccine for the Time and Place

Enhanced determination of Streptococcus pneumoniae serotypes associated with invasive disease in Laos by using a real-time polymerase chain reaction serotyping assay with cerebrospinal fluid.

A prospective hospital-based study was undertaken to define the incidence of invasive pneumococcal disease (IPD) and circulating serotypes in Laos. Of 10,799 patients with hemocultures and 353 patients with cerebrospinal fluid samples, 0.21% and 5.4%, respectively, were positive for Streptococcus pneumoniae, giving a total of 35 IPD patients. We developed a real-time polymerase chain reaction to detect serotypes represented in the 13-valent pneumococcal vaccine. A blinded evaluation comparing serotype as defined by the Quellung reaction versus the polymerase chain reaction demonstrated 100% concordance. The most frequent serotype (n = 33 patients) was 1 (n = 6), followed by serotypes 5, 6A/B/C, 14, and 23F. Serotypes represented in the 7-valent polysaccharide-protein conjugate vaccine (PCV-7) infected 39% of patients, with 73% coverage for the PCV-10 and PCV-13 vaccines. Although the sample size is small, these data suggest that the PCV-7 vaccine may have relatively low efficacy in Laos. Further studies are urgently needed to guide pneumococcal vaccine policy in Laos.

Ten-year surveillance of invasive Streptococcus pneumoniae isolates in central Turkey prior to the introduction of a conjugate vaccine

The aim of this study was to characterize the serotypes and antimicrobial susceptibility patterns of invasive Streptococcus pneumoniae isolates in central Turkey. A total of 332 invasive S. pneumoniae isolates were identified, serotyped and tested for antimicrobial susceptibility by routine microbiological methods. The most common serogroups/serotypes were 1, 19, 3, 18, 6, 14, and 7 in rank order. Serogroup/serotype coverage of the 23-valent polysaccharide vaccine, and the 7-, 10-, and 13-valent conjugate vaccines were 96%, 44%, 78.6%, 96.4%, respectively. Overall, 20 (6%) of the isolates were resistant to penicillin, 1 (0.3%) to cefotaxime, 20 (6%) to erythromycin, 13 (4%) to cloramphenicol, and 120 (36%) to trimethoprim-sulfamethoxasole. Among cerebrospinal fluid (CSF) isolates, 20 (18.5%) were resistant to penicillin (26.3% and 11.5%, respectively, of child and adult meningitis cases; p ≥ 0.05). Although the seven-valent conjugate vaccine is expected to protect less than half of children younger than three years of age, of the incorporation of this vaccine into the routine immunization program of Turkey is advised to continue. However, the 13-valent conjugate vaccine, including serotypes 1, 3, 5, and 7, has the most potential prevent the highest burden of invasive pneumococcal diseases in this age group.

Serotype-Specific Typing Antisera for Pneumococcal Serogroup 6 Serotypes 6A, 6B, and 6C

Streptococcus pneumoniae strains can express one of at least 92 capsular serotypes. To our knowledge, our laboratory is one of two that maintain antisera for resolution of the first 90 discovered pneumococcal serotypes (4; unpublished data). Recently, the evaluation of serogroup 6 isolates using monoclonal antibodies led to the discovery of the 91st serotype, 6C (7), which has become the prevalent invasive serogroup 6 serotype within the United States (2, 9). The pneumococcal 7-valent conjugate vaccine (PCV7) does not protect against it, and it is not included within the newly licensed 13-valent conjugate vaccine. In addition, serotype 6C carriage may also be common within PCV7-vaccinated populations (3). Prior to the discovery of serotype 6C, serotypes 6A and 6B were the 2 known serogroup 6 serotypes. CDC antisera for quellung-based resolution of serotypes 6A and 6B are designated as Danish factors 6b and 6c (DF-6b and DF-6c), respectively. Our original DF-6b antiserum was positive for both 6A and 6C serotypes, preventing their resolution (Table ​(Table11). TABLE 1. DF-6b, DF-6c, and DF-6d quellung results We produced DF-6d antiserum specific to serotype 6C and DF-6b antiserum specific to 6A as follows. New Zealand White female rabbits were inoculated with S. pneumoniae serotypes 6C or 6A formalin-fixed whole cells. The inocula consisted of serotype 6C or 6A cell suspensions (108 to 109 cells per ml in phosphate-buffered saline), which were administered intravenously via the marginal ear vein (Table ​(Table2).2). Blood was drawn after week 4 of dosing, and serum was evaluated for antibody titer to serotype 6C or 6A and cross-reactivity to serotypes 6A, 6B, and 6C by the quellung reaction. Cross-reactivity was removed from DF-6d by absorbing the serum with formalin-fixed cells of serotypes 6A and 6B. DF-6b antiserum was absorbed with formalin-fixed cells of serotypes 6B and 6C. The resulting DF-6d antiserum was specific for serotype 6C only, and DF-6b was specific to 6A only (Table ​(Table11). TABLE 2. Dosing schedule for preparation of antisera The specificity of DF-6b, DF-6c, and DF-6d antisera was evaluated with stock strains and 159 clinical isolates, each representing one of the serotypes 6A, 6B, or 6C. For all strains, Neufeld quellung results were compared to PCR testing specific for the serotype 6C wicN6C locus (2, 7, 8) with no inconsistencies observed. We have replaced our previous methods with these procedures for producing specific factor sera against serotypes 6A and 6C. We have now learned that Statens Serum Institute (SSI) has also recently produced factor 6d against serotype 6C (5). Our DF-6b, unlike the SSI factor 6b, is now serotype 6A specific and does not cross-react against serotype 6C. Serotype 6C-specific antiserum will be useful for laboratories which utilize quellung testing. Recently a fourth serogroup 6 serotype, serotype 6D, has been discovered in nature (1, 6) that is recognizable by a positive quellung test for serotype 6B combined with a positive PCR test for wciN6C. Despite extensive screening, we have not yet encountered this serotype (2). We do not yet know if our DF-6d antiserum would cross-react with serotype 6D. Consequently we screen all quellung test 6B strains by PCR for the presence of wciN6C (2, 8).

Immunisation of immunocompromised children against pneumococcus: which vaccine should now be used?: Abstract G164 Table 1

Although efficacy has never been demonstrated in children, 23-valent pneumococcal vaccine (PPV23) consisting of multiple unconjugated capsular polysaccharides has long been recommended for many children in high risk groups. Even since licensure of lower valency conjugated vaccines for which efficacy data are strong, PPV23 has continued to be recommended as part of a combined schedule and for children aged &gt;5 years. Children with chronic renal diseases are representative of broader high risk groups having susceptibility both related to primary disease and immunosuppressive treatment. The authors immunised PCV7-naïve children with seven valent conjugate vaccine (PCV7) and 6 m later with a test dose (0.1 ml) of 23valent polysaccharide vaccine (challenge). Serum was collected immediately before (V1 and V3) and 28–42 days after (V2 and V4) each vaccine dose and assayed (Luminex bead) for IgG antibody to PCV7 serotypes (ST). 75 children (51 male) aged 2.6–18.7 years (mean 11.5) were enrolled in three UK centres. 42 were post-renal transplant and 19 had chronic renal failure, of whom eight were on renal replacement therapy and two were awaiting transplant. Two had glomerulonephritis with low C3 and/or C4 and 14 had nephrotic syndrome that was steroid resistant and/or frequently relapsing. Geometric mean concentrations (n=55, μg/ml) at the four study visits (V) are shown in the table. Serum antibody responses to PCV7 showed mean 14.1-fold rises (range 5.8–19.1 for the seven serotypes). 75% (ST4) to 88% (STs 18C and 23F) achieved serum concentrations ≥0.35 μg/ml. After falling to mean 0.5 of post immunisation, a mean twofold titre rise (range 1.5–2.4) occurred after challenge, suggesting immunological memory. Children (n=10) who had received PPV23 prior to the study had much lower responses to PCV7 (p=0.01) suggesting hyporesponsiveness but had similar fold-rises (p=0.52) on PPV23 challenge. PCV7 was highly immunogenic in these immunocompromised children. These results confirm that, after inducing short-lived antibody responses, PPV23 induces hyporesponsiveness to pneumococcal antigens. With the availability of 10- and 13-valent conjugate vaccines, in the absence of evidence of benefit and in the presence of evidence of potential harm, consideration should now be given to cessation of use of PPV23 in childhood.

The effect of Haemophilus influenzae type b and pneumococcal conjugate vaccines on childhood pneumonia incidence, severe morbidity and mortality

Background With the aim of populating the Lives Saved Tool (LiST) with parameters of effectiveness of existing interventions, we conducted a systematic review of the literature assessing the effect of Haemophilus influenzae type b (Hib) and pneumococcal (PC) conjugate vaccines on incidence, severe morbidity and mortality from childhood pneumonia.Methods We summarized cluster randomized controlled trials (cRCTs) and case–control studies of Hib conjugate vaccines and RCTs of 9- and 11-valent PC conjugate vaccines conducted in developing countries across outcome measures using standard meta-analysis methods. We used a set of standardized rules developed for the purpose of populating the LiST tool with required parameters to promote comparability across reviews of interventions against the major causes of childhood mortality. The estimates could be adjusted further to account for factors such as PC vaccine serotype content, PC serotype distribution and human immunodeficiency virus prevalence but this was not included as part of the LiST model approach.Results The available evidence from published data points to a summary effect of the Hib conjugate vaccine on clinical pneumonia of 4%, on clinical severe pneumonia of 6% and on radiologically confirmed pneumonia of 18%. Respective effectiveness estimates for PC vaccines (all valent) on clinical pneumonia is 7%, clinical severe pneumonia is 7% and radiologically confirmed pneumonia is 26%.Conclusions The findings indicated that radiologically confirmed pneumonia, as a severe morbidity proxy for mortality, provided better estimates for the LiST model of effect of interventions on mortality reduction than did other outcomes evaluated. The LiST model will use this to estimate the pneumonia mortality reduction which might be observed when scaling up Hib and PC conjugate vaccination in the context of an overall package of child health interventions.

Susceptibility of Recently Collected Spanish Pneumococci Nonsusceptible to Oral Penicillin from Serotypes Not Included in the 7-Valent Conjugate Vaccine

The susceptibilities of pneumococci recently collected (up to June 2009) in Spain (500 isolates nonsusceptible to oral penicillin and 150 susceptible isolates) from serotypes not included in the conjugate vaccine were determined. Most nonsusceptible isolates (53.6%) belonged to serotype 19A. Susceptibility rates in serotype 19A penicillin-intermediate (n = 201)/penicillin-resistant (n = 67) isolates were <33%/< or =6.0% (erythromycin and oral cephalosporins with defined breakpoints), 85.1%/11.9% (amoxicillin), and 96.0%/52.2% (cefotaxime), respectively. Low susceptibility to common oral beta-lactams was also found in serotypes 11A (95.5% susceptibility to cefotaxime and erythromycin) and 35B.

Concomitant administration of recombinant PsaA and PCV7 reduces Streptococcus pneumoniae serotype 19A colonization in a murine model

A murine colonization model was used to determine the effect of co-administering 7-valent polysaccharide-protein conjugate vaccine and pneumococcal surface adhesin A. Mice were challenged intranasally with either PCV7 serotypes, 4 or 14, or a non-PCV7 serotype, 19A. Post-challenge samples were evaluated for IgG antibody levels, opsonophagocytic activity, and nasopharyngeal colonization. No interference was observed between immune responses from the concomitant and individual immunizations. Concomitant immunizations reduced carriage for tested serotypes; largest reduction was observed for 19A. From these mouse studies, co-administering pneumococcal antigens appear to expand coverage and reduce colonization against a non-PCV7 serotype without inhibiting immunogenicity to other serotypes.