Pneumococcal conjugate vaccines—a European perspective

Maternal immunization with pneumococcal surface protein A provides the immune memories of offspring against pneumococcal infection

Introduction

Streptococcus pneumoniae (S. pneumoniae) is one of the most widespread pathogens in the world and one of the largest infectious causes of infant mortality. Although current vaccines have various benefits, antibiotic resistance and the inability to vaccinate infants less than one year old demands the development of new protective strategies. One strategy, 'maternal immunization', is to protect infants by passive immunity from an immunized mother, although its mechanism is still not fully understood.

Materials and methods

The current study aimed to acquire immunity against S. pneumoniae in infants by maternal immunization with pneumococcal common antigen, pneumococcal surface protein A (PspA). Four-week-old female mice were immunized with recombinant PspA intranasally twice a week for three weeks. Females were mated with age-matched males after immunization, and delivered offspring.

Results

The week-old offspring derived from and fostered by immunized mothers had more anti-PspA-specific antibody producing cells in the spleen than those derived from sham-immunized mothers. The offspring were raised up to four weeks old and were subcutaneously stimulated with recombinant PspA. The levels of anti-PspA IgG in sera after stimulation were significantly higher in the offspring derived from the immunized mothers and the induced specific antibody to PspA showed protective efficacy against systemic pneumococcal infection.

Discussion

Maternal immunization is suggested to be able to provide a sustained immune memory to offspring. The current study would be a milestone in the field of maternal immunization toward a universal pneumococcal vaccine.

[Infant mortality in the European Union: A time trend analysis of the 1994-2015 period]

BACKGROUND

Infant mortality is an indicator of child health, and an explanatory variable to reflect the socioeconomic development of a country. We aimed to examine the changes and trends of infant mortality in the European Union (EU) and its 28 member states in the 1994-2015 period.

METHODS

We extracted data of deaths in children aged less than one year between 1994 and 2015 from the Eurostat database. We analysed secular variation in the EU overall, by country and by geographical region using joinpoint regression analysis. We conducted additional analyses to examine neonatal and early neonatal mortality trends.

RESULTS

Infant mortality in the EU has declined significantly from 8,3 to 3,6 per 1,000 live births (annual percent change=-3,8%; 95% confidence interval, -4,1 to -3,6). Among EU countries, we found the highest mortality rates throughout the study period in Romania and Bulgaria, and the lowest rates in Scandinavian countries (Finland, Sweden). There were significant decreasing trends in every country of the EU, which were most pronounced in former Soviet Baltic states and Eastern European countries, and least pronounced in Western European countries. Mortality rates have increased significantly in Greece in the last years, and plateaued in the United Kingdom and Ireland.

CONCLUSIONS

Our findings, which are based on official data, provide consistent evidence that infant mortality has declined steadily in the EU and its member states in the past decades, most markedly in Eastern European countries and former Soviet Baltic states. However, rates have risen or levelled off in some western countries in the past few years.

Pneumococcal meningitis and vaccine effects in the era of conjugate vaccination: results of 20 years of nationwide surveillance in Germany

Background

Long-term complications and a case mortality rate of 7.5% make meningitis caused by Streptococcus pneumoniae a serious clinical threat. In 2006, a general pneumococcal conjugate vaccination (PCV) recommendation was issued for all children under 2 years in Germany. Here, we investigate serotype changes in meningitis cases after this vaccine recommendation.

Methods

The German National Reference Center for Streptococci (NRCS) has conducted surveillance for invasive pneumococcal disease (IPD) in Germany since 1992. Pneumococcal isolates were serotyped by the Neufeld’s Quellung reaction and antibiotic susceptibility was tested using the broth microdilution method.

Results

Of 22,204 IPD isolates sent to the NRCS from July 1992 to June 2013, 3,086 were meningitis cases. Microbiological and statistical investigations were performed to characterize and quantify all meningitis cases, focusing on changes reflecting implementation of the national PCV recommendation. 1,766 isolates (57.2% of meningitis cases) were from adults (≥16 years) and 1,320 isolates (42.8%) originated from children (<16 years). Overall, the leading serotypes were 14 (9.7%), 7F (7.8%), 3 (6.9%), 19F (5.7%) and 23F (5.0%). Among children, serotypes 14 (16.2%), 7F (8.9%) and 19F (7.1%) were most common, whereas among adults, serotypes 3 (9.6%), 7F (6.9%), 22F (5.0%), 23F (4.9%) and 14 (4.8%) were most prevalent. After the introduction of general PCV7/10/13 vaccination a significant decrease for most vaccine serotypes was observed. Generally, the differences in antibiotic nonsusceptibility between children <16 years and adults ≥16 were low. For macrolides in the pre-PCV7 period, a significantly higher proportion of resistant isolates was found in children (25.1%), compared to the post-vaccination period (9.7%; p<0.0001).

Conclusions

Implementation of the pneumococcal conjugate vaccines broadly reduced vaccine-type meningitis cases. Changes in serotype prevalence must be continuously monitored to observe future trends concerning pneumococcal meningitis.

Successful serology-based intervention to increase protection against vaccine-preventable diseases in liver-transplanted children: a 19-yr review of the Swiss national reference center

As children referred for OLT in Switzerland were not vaccinated optimally, new guidelines were developed and recommended to base catch-up immunization on serum antibody titers against vaccine-preventable diseases, before and after OLT. We measure the results of this serology-based intervention by comparing vaccine coverage and antibody titers in the pre- (1990-2002, P1) and post-intervention (2003-2008, P2) cohorts in a quality control project. Forty-four P1 and 30 P2 children were evaluated. At pre-OLT visit, D, T, SPn, and MMR serologies were checked more frequently in P2 than P1 (p < 0.05). More P2 children were up-to-date for DTaP and MMR (p < 0.05) or had received ≥1 dose of HBV, HAV, SPn, and VZV vaccines (p < 0.05). One yr post-OLT, DT, SPn, MMR, and VZV serologies were more frequently checked (p < 0.05), and antibody titers were higher for DT and HAV (p < 0.05) in P2. Gender, age, or diagnosis did not explain these differences. Among P2 patients, pre- and post-OLT titers for D, T, Hib, HBV, SPn14, and SPn19 were correlated (p < 0.05 for all). Protection against vaccine-preventable diseases of high-risk children like OLT patients can be significantly improved by serology-based intervention for vaccine-preventable diseases.

Serotypes of Streptococcus pneumoniae isolates from children with invasive pneumococcal disease in Turkey: baseline evaluation of the introduction of the pneumococcal conjugate vaccine nationwide

Before use of the pneumococcal conjugate vaccine PCV7 became widespread in Turkey, 202 invasive pneumococcus isolates were analyzed. The most common serotypes were 19F and 6B. In children ≤2 years of age, the potential coverage rate of PCV7 was 69.5%. The most frequent non-PCV7 serotypes were 19A, 3, 1, 6A, and 8.

Macrolide susceptibility and serotype specific macrolide resistance of invasive isolates of Streptococcus pneumoniae in Germany from 1992 to 2008

Background

Macrolide resistant Streptococcus pneumoniae has been on a gradual increase in Germany for over a decade. The current study was undertaken against the background of the recent observation of declining macrolide resistance rates especially among German children. Nationwide surveillance of invasive pneumococcal disease has been conducted in Germany since 1992. A population- and laboratory-based approach was used to collect data on invasive pneumococcal disease, and isolates sent to the National Reference Center for Streptococci by diagnostic microbiological laboratories from 1992 to 2008 were included in this study.

Results

From 1992 to 2008, data on macrolide susceptibility were available for 11,807 invasive isolates. 8,834 isolates (74.8%) were from adults (≥ 16 years), and 2,973 isolates (25.2%) from children (< 16 years). The overall nonsusceptibility rate of all isolates was 16.2% (intermediate, 0.2%; resistant, 16.0%). Higher resistance rates were observed among children (intermediate, 0.2%; resistant, 23.8%) than among adults (intermediate, 0.3%; resistant 13.4%). Maximum nonsusceptibility rates during the period under study were observed in 2005 (children: intermediate, 0.3%; resistant, 32.3%; adults: intermediate, 0.0%; resistant, 18.6%), while nonsusceptibility rates in 2008 were considerably lower, especially for children (children: intermediate, 0.0%; resistant, 15.2%; adults: intermediate, 0.1%; resistant, 12.9%). The rate of resistance was higher among the vaccine serotypes (7-valent, 36.6%; 10-valent, 28.2%; 13-valent, 24.3%) than among the non vaccine serotypes (non 7-valent, 6.5%; non 10-valent, 7.4%; non 13-valent, 6.3%). Serotype 14 (69.6% nonsusceptibility) proved to be the most resistant serotype.

Conclusions

There has been a considerable and statistically significant decrease in macrolide nonsusceptibility in Germany since 2005, especially among children.

Temporal Variations among Invasive Pneumococcal Disease Serotypes in Children and Adults in Germany (1992-2008)

Nationwide surveillance of invasive pneumococcal disease has been conducted in Germany since 1992. From 1992 to 2008, a total of 12,137 isolates from invasive pneumococcal disease were collected. Data on serotypes were available for 9,394 invasive isolates. The leading serotypes were serotypes 14 (16.5%), 3 (8.0%), 7F (7.6%), 1 (7.3%), and 23F (6.0%). Variations in serotype distribution over the years are particularly extensive, especially concerning serotype 14 (min 7.4%, max 33.5%) with the highest percentages among the isolates serotyped from around 1997 to 2006. Serotypes 1 and 7F increased over the last decade. No increase was observed concerning serotype 19A. Higher pneumococcal conjugate vaccine coverages were observed among children (7v, 57.3%; 10v, 72.8%; 13v, 83.5%) than among adults (7v, 39.9%; 10v, 55.5%; 13v, 73.5%). The temporal variations in serotype distribution have to be kept in mind when interpreting vaccine coverages reported in epidemiological studies.

Association of serotypes of Streptococcus pneumoniae with age in invasive pneumococcal disease

A total of 7,764 isolates from patients with invasive pneumococcal disease (IPD) were collected from 1992 to June 2006. Data on serotypes were available for 5,022 isolates (64.7% of all invasive isolates). Some 54.0% of the isolates originated from adults >or=16 years of age, and 46.0% were from children <16 years of age. The leading serotypes were 14, 23F, 1, 6B, 7F, 3, and 4. The serotypes significantly more common in children were 14, 6B, 19F, and 18C, while among adults, serotypes 3 and 4 were predominant. Serotype 7F was statistically more prevalent among children <4 months old than among the other age groups. Among children aged >or=4 months and <1 year, serotype 19F occurred statistically more frequently; and among children aged >or=1 year to <5 years, serotypes 14, 6B, and 18C were overrepresented. The serotypes predominantly affecting patients younger than the remaining collective of patients were 14, 6B, 19F, and 18C, while patients with IPD caused by serotypes 3, 4, and 9V were older than the collective, on average.

Community-acquired upper respiratory tract infections and the role of third-generation oral cephalosporins

Common community-acquired infections include those of the upper respiratory tract. In the 1990s, the antimicrobial treatment of upper respiratory tract infections focused on penicillin-resistant Streptococcus pneumoniae. However, following the introduction of a pneumococcal conjugate vaccine, a decrease in invasive pneumococcal disease occurred, and in the case of otitis media a shift towards Haemophilus influenzae as the predominant causative pathogen was observed. Future antimicrobial therapy for outpatient upper respiratory tract infections may need to focus on pathogens such as penicillin-susceptible S. pneumoniae, beta-lactamase-producing H. influenzae, beta-lactamase-negative amoxicillin-resistant H. influenzae and Moraxella catarrhalis. In these circumstances, third-generation oral cephalosporins, such as cefixime and cefdinir, could be increasingly used as an optional first-line therapy in community practice for upper respiratory tract infections suspected to be caused by these key pathogens, as an alternative to amoxicillin-clavulanate.

Serotype and antibiotic resistance of isolates from patients with invasive pneumococcal disease in Japan

Invasive pneumococcal disease (IPD) is of concern in Japan, where the heptavalent pneumococcal conjugate vaccine (PCV7) is unavailable. We determined serotypes, genotypes indicating beta-lactam resistance, and antibiotic susceptibilities of 496 isolates from normally sterile sites in patients (193 children, 303 adults) from 186 institutions between August 2006 and July 2007. Disease presentations included sepsis (46.2%), pneumonia (31.5%), and meningitis (17.5%). Mortality was 1.4% in children and 22.1% in adults, many of whom had underlying diseases. In children, serotype 6B (22.5%) was followed by 19F (14.1%), and 14 (13.1%); potential coverages of PCV7 and PCV13 were 75.4% and 93.7%, respectively. In adults, serotype 12F (14.3%) was followed by 3 (11.3%), and 6B (10.3%); 23-valent polysaccharide vaccine (PPV23) coverage was 85.4%. Most serotype 12F strains were gPISP, with pbp2b gene alteration; carbapenem had an excellent MIC90. PCV7 is recommended for children and PPV23 for adults to increase prevention against IPD.

National paediatric immunization program of high risk groups: no effect on the incidence of invasive pneumococcal diseases

This study monitors the epidemiology of invasive pneumococcal diseases (IPD) in hospitalized children up to 60 months of age before (February 2001-October 2004) and after (November 2004-January 2007) the introduction of a national risk group immunization program with "Prevenar" in Austria. The IPD incidence rates, per 100,000, for IPD were 7.6 before and 6.4 after the risk group immunization program, while there was a significant reduction (p<0.05) for meningitis, 3.1 before and 1.6 after. Overall, the most commonly observed serotypes were 14 (34.2%), 6B (11.7%), and 23F (6.7%). 71.7% of the identified strains were vaccine types; 12.5% were vaccine-related serotypes. No clinically relevant changes in the incidence rate of IPDs or shift/replacement of serotypes was documented. Antimicrobial resistance predominated against erythromycin (32.5%) and clarithromycin (26.7%). Our data show that this risk group vaccination program had no impact on the incidence of IPD in young children.

Rapid detection of eight causative pathogens for the diagnosis of bacterial meningitis by real-time PCR

We aimed to detect causative pathogens in cerebrospinal fluid (CSF) collected from patients diagnosed with bacterial meningitis by real-time polymerase chain reaction (PCR). In addition to Streptococcus pneumoniae, Haemophilus influenzae, and Mycoplasma pneumoniae described previously, five other pathogens, Neisseria meningitidis, Escherichia coli, Streptococcus agalactiae, Staphylococcus aureus, and Listeria monocytogenes, were targeted, based on a large-scale surveillance in Japan. Results in CSF from neonates and children (n=150), and from adults (n=18) analyzed by real-time PCR with molecular beacon probes were compared with those of conventional culturing. The total time from DNA extraction from CSF to PCR analysis was 1.5 h. The limit of detection for these pathogens ranged from 5 copies to 28 copies per tube. Nonspecific positive reactions were not recognized for 37 microorganisms in clinical isolates as a negative control. The pathogens were detected in 72.0% of the samples by real-time PCR, but in only 48.2% by culture, although the microorganisms were completely concordant. With the real-time PCR, the detection rate of H. influenzae from CSF was high, at 45.2%, followed by S. pneumoniae (21.4%), S. agalactiae (2.4%), E. coli (1.8%), L. monocytogenes (0.6%), and M. pneumoniae (0.6%). The detection rate with PCR was significantly better than that with cultures in patients with antibiotic administration (chi2=18.3182; P=0.0000). In conclusion, detection with real-time PCR is useful for rapidly identifying the causative pathogens of meningitis and for examining the clinical course of chemotherapy.

Otitis Media: A Review, with a Focus on Alternative Treatments

Otitis media (OM) is the accumulation of fluids in the middle ear, with or without symptoms of inflammation. The infection is caused by dysfunction or obstruction of the eustachian tube and is most commonly diagnosed in children under the age of two. The microbiology of OM differs, with Streptococcus pneumoniae, non-typeable Haemophilus influenzae and Moraxella catarrhalis the most commonly isolated pathogens. The emergence of penicillin-resistant Strep. pneumoniae, β-lactamase-producing strains, Haem. influenzae and Mor. catarrhalis is a major concern and health care costs associated with treatment are substantial, especially in cases of unresponsive treatment as a result of incorrect diagnosis. Alternative treatments such as vaccines and a nasal spray containing α-haemolytic streptococci with antimicrobial activity against OM pathogens, have been developed. The rationale behind such treatments is to induce an appropriate immune response against the pathogens and decrease bacterial colonisation in the nasopharynx. Another approach may be treatment with bacteriocins (natural antimicrobial peptides) or bacteriocin-like inhibitory substances (BLIS) produced by lactic acid bacteria. We have recently described an antibacterial peptide produced by Enterococcus mundtii ST4SA and have published on bacteriocins (enterocins) with antibacterial and antiviral activity. This review discusses the condition OM, summarises current methods used to treat the infection, and suggests alternative safe and natural treatments that need to be explored.

Multidrug-resistant Streptococcus pneumoniae infections: current and future therapeutic options

Antibacterial resistance in Streptococcus pneumoniae is increasing worldwide, affecting principally beta-lactams and macrolides (prevalence ranging between approximately 1% and 90% depending on the geographical area). Fluoroquinolone resistance has also started to emerge in countries with high level of antibacterial resistance and consumption. Of more concern, 40% of pneumococci display multi-drug resistant phenotypes, again with highly variable prevalence among countries. Infections caused by resistant pneumococci can still be treated using first-line antibacterials (beta-lactams), provided the dosage is optimised to cover less susceptible strains. Macrolides can no longer be used as monotherapy, but are combined with beta-lactams to cover intracellular bacteria. Ketolides could be an alternative, but toxicity issues have recently restricted the use of telithromycin in the US. The so-called respiratory fluoroquinolones offer the advantages of easy administration and a spectrum covering extracellular and intracellular pathogens. However, their broad spectrum raises questions regarding the global risk of resistance selection and their safety profile is far from optimal for wide use in the community. For multi-drug resistant pneumococci, ketolides and fluoroquinolones could be considered. A large number of drugs with activity against these multi-drug resistant strains (cephalosporins, carbapenems, glycopeptides, lipopeptides, ketolides, lincosamides, oxazolidinones, glycylcyclines, quinolones, deformylase inhibitors) are currently in development. Most of them are only new derivatives in existing classes, with improved intrinsic activity or lower susceptibility to resistance mechanisms. Except for the new fluoroquinolones, these agents are also primarily targeted towards methicillin-resistant Staphylococcus aureus infections; therefore, demonstration of their clinical efficacy in the management of pneumococcal infections is still awaited.

Nasal immunization of mice with Lactobacillus casei expressing the Pneumococcal Surface Protein A: induction of antibodies, complement deposition and partial protection against Streptococcus pneumoniae challenge

Strategies for the development of new vaccines against Streptococcus pneumoniae infections try to overcome problems such as serotype coverage and high costs, present in currently available vaccines. Formulations based on protein candidates that can induce protection in animal models have been pointed as good alternatives. Among them, the Pneumococcal Surface Protein A (PspA) plays an important role during systemic infection at least in part through the inhibition of complement deposition on the pneumococcal surface, a mechanism of evasion from the immune system. Antigen delivery systems based on live recombinant lactic acid bacteria (LAB) represents a promising strategy for mucosal vaccination, since they are generally regarded as safe bacteria able to elicit both systemic and mucosal immune responses. In this work, the N-terminal region of clade 1 PspA was constitutively expressed in Lactobacillus casei and the recombinant bacteria was tested as a mucosal vaccine in mice. Nasal immunization with L. casei-PspA 1 induced anti-PspA antibodies that were able to bind to pneumococcal strains carrying both clade 1 and clade 2 PspAs and to induce complement deposition on the surface of the bacteria. In addition, an increase in survival of immunized mice after a systemic challenge with a virulent pneumococcal strain was observed.

Acute bacterial meningitis among children, in Manhiça, a rural area in Southern Mozambique

INTRODUCTION

Acute bacterial meningitis (ABM) is one of the most severe diseases in Sub-Saharan Africa. Although data for the continent is very limited, more than one million cases are estimated per year, with mortality and life-long sequelae occurring in 50% of these cases.

METHODS

As part of the clinical management of children admitted to the Manhiça District Hospital, information on cases of ABM was recorded. We analysed data from June 1998 to November 2003.

RESULTS

During the study period, 475 cerebrospinal-fluid (CSF) samples were collected from 20,173 children <15 years of age admitted to hospital. Culture results confirmed 71 (15%) cases of ABM. The most prevalent bacterial aetiologies were Streptotoccus pneumoniae (pneumococcus, n=31), Haemophilus influenzae (n=13) and Neisseria meningitis (n=8). Other important bacteria were Streptococcus sp. (n=7), Salmonella sp. (n=4) and Staphylococcus aureus (n=3). Crude incidence rates of ABM and pneumococcal meningitis were 20/100,000 and 10/100,000 children-year-at-risk, respectively. Incidences were more than three times higher in the <1 year age group. Overall case fatality rate was 36%, and was highest for H. influenzae and pneumococcal meningitis (55% and 45%, respectively, p=0.044). Pneumococcal susceptibility was 81% for oxacillin and 93% for chloramphenicol. For H. influenzae isolates, susceptibility was 54% for ampicillin and 62% for chloramphenicol.

CONCLUSIONS

S. pneumoniae and H. influenzae are the main aetiologies responsible for the high burden of morbidity and mortality associated with ABM in rural Mozambique. These findings are important to evaluate treatment guidelines and potential impact of control measures.

Invasive pneumococcal disease in Portugal prior to and after the introduction of pneumococcal heptavalent conjugate vaccine

The rates of invasive pneumococcal disease (IPD), serotype distribution and antimicrobial susceptibility prior to and after the introduction of the heptavalent pneumococcal conjugate vaccine in Portuguese children were evaluated. The changes in incidence of IPD in children under 1 year old between the two periods of the study was not significant (P=0.53), despite the 21% decline. In children under 18 years old there was a 27.7% decrease in vaccine serotypes. All nonvaccine serotypes increased 71.4%. The decrease in vaccine serotypes was more impressive during the first year of life (-54.8%) than for children between 1 and 5 years of age (-19.1%). Among children under 1 year old, penicillin nonsusceptible isolates declined between the two periods of the study (47.2% vs. 25.0%) (P=0.03), as did those of cefotaxime and ceftriaxone nonsusceptible isolates. No changes were observed for isolates nonsusceptible to tetracycline and macrolides. The serotypes of these nonsusceptible isolates differed after the introduction of vaccine (P=0.01). Multiresistance increased 57.1% after the introduction of vaccine. Multiresistant isolates with vaccine serotype declined 42.9% (P<0.001), and nonvaccine serotypes appeared during the vaccination period (P<0.001). These findings suggest a replacement of vaccine serotypes by nonvaccine serotypes, mainly among nonsusceptible isolates.

Trends in resistance to penicillin and erythromycin of invasive pneumococci in Portugal

Antimicrobial resistance of pneumococci is influenced by serotypes, antimicrobial consumption and vaccine use. Serotyping of 697 out of 1331 pneumococcal isolates, recovered in Portugal from 1994 to 2004, showed that the theoretical rate of heptavalent conjugate vaccine coverage was 91.7% and 63.6% for penicillin and erythromycin non-susceptible strains, respectively, in children up to 1 year old. The use of amoxicillin and erythromycin decreased in the vaccine period 2001-2004 (P=0.04 and P<0.01, respectively) but azithromycin usage increased in the same period (P<0.01). By using linear regression models, we evaluated the role of antimicrobial and vaccine use in the trends of resistance to penicillin and erythromycin among the isolates. The models suggest that the use of macrolides was the main factor associated with an increase of penicillin and erythromycin non-susceptible isolates from adults (P<0.01) and erythromycin non-susceptible isolates among children (P=0.006). These models also suggest that heptavalent vaccine is failing to reduce antimicrobial resistance as expected, possibly due to the increased consumption of azithromycin (P=0.04). The efficient use of new antibiotics may reverse the present trends of antimicrobial resistance.

Streptococcus pneumoniae virulence factors and their clinical impact: An update

The morbidity and mortality rates associated with Streptococcus pneumoniae remain very high worldwide. The virulence of this bacterium is largely dependent on its polysaccharide capsule, which is quite heterogeneous and represents a serious obstacle for designing effective vaccines. However, it has been demonstrated that numerous protein virulence factors are involved in the pathogenesis of pneumococcal disease. An important related finding from experimental animal models is that non-capsulated strains of pneumococci are protective against capsulated ones. Hence, new vaccine designs are focused on the surface proteins (e. g., PspA and PspC) and on the cytolysin, pneumolysin. Moreover, several virulence factors have potential value for pneumococcal diagnosis by urinalysis. In this paper, we review the virulence factors involved in bacteria-host interactions, and the new developments in vaccines and diagnostic methods.

Molecular epidemiology of penicillin-non-susceptible Streptococcus pneumoniae isolates from children with invasive pneumococcal disease in Germany

A population-based nationwide surveillance of antibiotic resistance associated with invasive pneumococcal disease (IPD) in children and adolescents (aged<16 years) was performed in Germany between 1997 and 2004. In total, 1517 isolates were collected, of which 5.1% and 1.1% were intermediately- or fully-resistant, respectively, to penicillin G. During the 8-year study period, an increase in resistance to both penicillin G and erythromycin A was observed, and the frequency of isolates exhibiting reduced susceptibility to penicillin G or erythromycin A increased from 1.4% and 11.1%, respectively, in 1997, to 8.7% and 29.0%, respectively, in 2004. Among the penicillin non-susceptible pneumococcal isolates, serotypes 14 (24.5% of isolates), 23F (16.0%) and 6B (16.0%) were found most frequently. Multilocus sequence typing of 58 (62%) penicillin G non-susceptible isolates revealed that sequence type (ST) 156 (Spain9V-3 clone) and its single-locus variant ST 557 were widespread in Germany. Moreover, 17 new penicillin G non-susceptible STs were defined for the first time. The study illustrated the genetic heterogeneity of antibiotic-resistant pneumococcal isolates in Germany.

Immunogenicity, efficacy, safety and effectiveness of pneumococcal conjugate vaccines (1998–2006)

In this paper we present an overview of the literature on efficacy and safety trials of the various pneumococcal conjugate vaccines on the market (PCV7) and in development (PCV9, PCV11 and allegedly PCV10 and PCV13), as well as of observations from post-licensure studies. Seven- (PCV7) and nine-valent PCV (PCV9) are reported to be sufficiently immunogenic after administration of a 3+1 schedule in infants in various RCTs. PncOMPC (PCV7 with a protein of N. meningitidis as a carrier) is less immunogenic, though this may have no repercussions for the protective efficacy against clinical disease. PCV7 is 82-97% efficacious against vaccine serotype (VT) IPD, 90% efficacious against (clinically diagnosed) pneumococcal pneumonia, and, like the 11-valent PCV, 57% efficacious against VT acute otitis media. Naturally, it would be of paramount public health interest if the same levels of efficacy and effectiveness could be achieved with fewer doses. Trials studying 2+1 vaccination schedules for PCV7 and PCV9 generally show that the percentage of infants achieving the protective cut-off set by the World Health Organization (WHO) 1 month after the last priming dose, is comparable to that found at the same time point in studies administering 3+1 schedules. PCVs are generally very well tolerated and safe, also when co-administered with other childhood vaccines. As more and more countries are using these vaccines routinely, post marketing surveillance studies will further establish the safety profile of PCVs.

Microbiologic Workload and Clinical Significance ofStreptococcus pneumoniaeIsolated during One Week in Spain

Most studies reporting Streptococcus pneumoniae (Sp) infections select either specific populations/diseases, or refer to a single or a low number of institutions. A nationwide point-prevalence study including 147 hospitals from which we collected all the isolates of Sp reported in a single week (February 16-22, 2004). Workload and clinical data were studied, and susceptibility testing and serotyping of all isolates were performed. The participating institutions had an estimated catchment population of 37,534,750 inhabitants. During the study week, microbiology laboratories received 224,956 samples of which 34,647 were positive and 360 had S. pneumoniae. Overall, 69% of the isolates were from adults (> or = 15 years). Most of the isolates (89%) were considered clinically significant. Infection was community-acquired in 88% of infections and monomicrobial in 79%. We calculated that S. pneumoniae was isolated 38 times per 100,000 inhabitants/year and it was present in 1% of all samples with one or more bacterial isolates. We also calculated that pneumococcal disease (invasive and noninvasive) was present in 34 patients per 100,000 inhabitants/year. Penicillin resistance (I+R) was 42%, and erythromycin resistance was 35%. The most frequent serotypes were 3, 19F, and 19A. Considering only invasive isolates, the estimated coverage of the 7-valent vaccine was 61% in children and 41% in adults, and the estimated coverage of the 23-valent vaccine in adults was 79%. A nationwide point-prevalence study is an efficient tool for surveying pneumococcal infection in a large population.

Vaccine-induced immunity in children after orthotopic liver transplantation: a 12-yr review of the Swiss national reference center

Infections represent a significant threat in solid-organ recipients. However, a certain number of infections can be prevented by immunizing patients before their transplantation. The aim of this study is to determine the level of immunity of children undergoing liver transplantation and to assess their capacity to maintain protective levels after surgery. Charts of 44 children transplanted with deceased donation livers between 1990 and 2002 at the Children's Hospital of Geneva were reviewed. Vaccine antibody responses were established pre- and post-transplantation. Only 43% of patients were up to date for diphtheria, tetanus, acellular pertussis, and polio vaccines at the pretransplantation visit, while 44% of children older than 12 months had received their required measles-mumps-rubella vaccines. Six of 44 children had received at least one dose of hepatitis B vaccine, while only two patients had received at least one dose of hepatitis A vaccine. After immunization, and one yr after transplantation, only 14 of 44 patients had detectable anti-HBs antibodies and seven of 18 had anti-HAV antibodies. Varicella antibodies were undetectable in 15 of 19 patients immunized prior to transplantation. This study highlights the need to enforce vaccination before transplantation, follow-up on vaccine- induced immunity, and adapt vaccination schedules after liver transplantation in children, especially for non-live vaccines, which are universally recommended in this population.

Serotype distribution of Streptococcus pneumoniae in north-western Greece and implications for a vaccination programme

Serotypes and antibiotic sensitivities were determined for 338 strains of Streptococcus pneumoniae from children of north-western Greece with invasive pneumococcal disease (IPD), acute otitis media (AOM) and nasopharyngeal carriage. The most common serotypes among the isolates from IPD were 14 and 19F, while 3, 19F, 9V and 14 were the major cause of AOM. In these groups, the heptavalent conjugate vaccine for pneumococci (7vPCV) seems to cover 90.5% of the serotypes isolated from children less than 2 years old. Serotypes 23F and 6B were the most prevalent in carrier strains. Overall, 23.7% of the isolates were penicillin nonsusceptible (PNS), 97% were fully susceptible to cefotaxime, 29% were resistant to erythromycin, 11.2% to co-trimoxazole and 1.2% to clindamycin.

Genetic diversity of pneumococcal surface protein A of Streptococcus pneumoniae meningitis in German children

Pneumococcal surface protein A (PspA) is a possible candidate for the development of a pneumococcal vaccine that has the potential to offer a broad range of protection. PspA genes of pneumococcal meningitis isolates (n=40) isolated as part of an ongoing population-based nation-wide surveillance program on invasive pneumococcal disease in children in Germany were analyzed to expand our knowledge on the distribution of PspA families of this important vaccine candidate in Germany. The serotype distribution of the strains was as follows: serotype 4 (n=3), 6B (5), 9V (2), 14 (8), 18C (6), 19F (5), 23F (6), and 7F (5). The pspA genes of these strains could be assigned to 2 families containing 20 pneumococcal strains each. Family I could be subdivided into 2 clades with 17 strains in clade 1 and 3 strains in clade 2, and family II could be subdivided into 3 subgroups (clades 3-5) containing 16, 3, and 1 strain, respectively. Pneumococcal serotypes were distributed evenly over all clades and families. Interestingly, the distribution of the PspA gene families in Germany was seen to differ slightly that found in other countries.

[Silent mastoiditis in a 5-month-old infant]

We report the case of a 5-month-old female infant who developed a progressive unilateral retroauricular swelling without further symptoms in the first 5 months of life. The otherwise healthy infant was breast fed and had no history of previous otitis media. The clinical suspicion of silent mastoiditis was confirmed by CT scans and the intraoperative finding of an abscess due to Streptococcus pneumoniae. The onset is unusual, since mastoid pneumatization develops only after birth, and it is presumed that maternal antibodies should protect the infant from serious infections within the first months of life.

Pneumococcal meningitis in adults: new approaches to management and prevention

Since the virtual eradication of meningitis due to Haemophilus influenzae type B by vaccination in the developed world, pneumococcal meningitis has become the leading cause of bacterial meningitis beyond the neonatal period. Clinical and experimental research has increased our knowledge about the pathophysiology and pathogenesis of the disease over the past decades. Despite the availability of effective antibiotics, supportive care facilities, and recent advances in adjunctive strategies-ie, adjunctive dexamethasone-mortality and morbidity rates associated with pneumococcal meningitis remain unacceptably high. Although preliminary results after the introduction of the pneumococcal conjugate vaccine are promising, the incidence of multidrug-resistant pneumococcal strains is rising worldwide. Here we discuss clinical aspects of pneumococcal meningitis in adults, with focus on pathophysiology, and stress the urgent need for adequate preventive measures and new effective treatments.

[Nonvaccine Streptococcus pneumoniae serotypes causing acute bacterial meningitis]

The pneumococcal heptavalent conjugate vaccine protects children aged less than 2 years old from invasive pneumococcal disease (IPD). Efficacy is 89-93% in the US population and 71-86% in European studies. The vaccine confers active immunization against the main serotypes causing IPD (4, 6B, 9V, 14, 18C, 19F y 23F). We describe 2 children who presented with pneumococcal meningitis caused by nonvaccine serotypes. As a result of the widespread use of the heptavalent vaccine, there may be a shift in the serotypes causing IPD.

Genetic analysis of the capsular biosynthetic locus from all 90 pneumococcal serotypes

Several major invasive bacterial pathogens are encapsulated. Expression of a polysaccharide capsule is essential for survival in the blood, and thus for virulence, but also is a target for host antibodies and the basis for effective vaccines. Encapsulated species typically exhibit antigenic variation and express one of a number of immunochemically distinct capsular polysaccharides that define serotypes. We provide the sequences of the capsular biosynthetic genes of all 90 serotypes of Streptococcus pneumoniae and relate these to the known polysaccharide structures and patterns of immunological reactivity of typing sera, thereby providing the most complete understanding of the genetics and origins of bacterial polysaccharide diversity, laying the foundations for molecular serotyping. This is the first time, to our knowledge, that a complete repertoire of capsular biosynthetic genes has been available, enabling a holistic analysis of a bacterial polysaccharide biosynthesis system. Remarkably, the total size of alternative coding DNA at this one locus exceeds 1.8 Mbp, almost equivalent to the entire S. pneumoniae chromosomal complement.

Invasive pneumococcal disease in adults in North-Rhine Westphalia, Germany, 2001-2003

A population-based survey of invasive pneumococcal disease (IPD) was conducted among adults in North-Rhine Westphalia, Germany. The study included 202 of the 386 hospitals in the region, together with the 27 microbiological laboratories that submitted reports of IPD in these hospitals to the National Reference Centre for Streptococci. The reports of 16 laboratories were comprehensively reviewed. Most (95.8%) IPD isolates were susceptible to penicillin G, but 14.5% were resistant to clarithromycin. Serotypes 14 (15.6%), 3 (9.3%), 4 (7.1%) and 7F (7.9%) were the most common. The serotype coverage of the 23-valent pneumococcal polysaccharide vaccine was 80.8%. During 2001-2003, the annual incidence of IPD, after correcting for laboratory and hospital under-reporting, was 16.2/100 000 in individuals aged >or= 65 years. In three university hospitals, blood cultures were obtained for only 37% of patients with community-acquired pneumonia, and fewer than one-third of such cultures were obtained in one hospital before antibiotics were prescribed, suggesting that the true incidence of IPD was closer to 50/100 000.

Does the 23-Valent Pneumococcal Vaccine Protect Cochlear Implant Recipients?

OBJECTIVES/HYPOTHESIS

The incidence of meningitis is increased in cochlear implant (CI) recipients. Besides malformations, immunological deficiencies are predisposing factors. Therefore, the immunological background of CI recipients and the immunogenicity of the recommended 23-valent pneumococcal polysaccharide vaccine (PPV-23) were investigated.

STUDY DESIGN

Prospective study in a tertiary care referral center.

METHODS

One hundred twenty CI recipients who were at least 5 years of age were vaccinated with PPV-23. Levels of immunoglobulins G, A, and M (IgG, IgA, and IgM, respectively) and IgG subclasses IgG1-IgG4 before vaccination and serum concentrations of antibodies against seven pneumococcal serotypes before and 4 weeks after vaccination were determined. The cohort was subdivided by patient age into groups A1 (5-8 y), A2 (8-12 y), and A3 (>12 y).

RESULTS

Geometric mean concentrations of pneumococcal antibodies before vaccination were remarkably low in all three groups, emphasizing the importance of vaccination in this risk group. All groups showed a statistically significant increase in geometric mean concentrations after immunization. For group A1 compared with groups A2 and A3, response was limited, especially for serotypes 6B (geometric mean concentration, 1.71 microg/mL; P = .0007), 23F (geometric mean concentration, 2.28 microg/mL; P = .04), and 14 (geometric mean concentration, 3.98 microg/mL; P = .0004). The percentages of patients reaching the presumed protective threshold of at least 1 microg/mL pneumococcal antibody concentration were at least 71.1% in group A1, 93.8% in group A2, and 90.5% in group A3. This raises the question of whether PPV-23 evokes satisfying seroprotection in CI recipients younger than 8 years of age.

CONCLUSION

With regard to the increased risk for bacterial meningitis, the authors recommend priming CI recipients younger than 8 years of age with pneumococcal conjugate vaccine followed by a PPV-23 booster.

A review of vaccine research and development: human acute respiratory infections

Worldwide, acute respiratory infections (ARIs) constitute the leading cause of acute illnesses, being responsible for nearly 4 million deaths every year, mostly in young children and infants in developing countries. The main infectious agents responsible for ARIs include influenza virus, respiratory syncytial virus (RSV), parainfluenza virus type 3 (PIV-3), Streptococcus pneumoniae and Haemophilus influenzae. While effective vaccines against influenza, H. influenzae type b (Hib) and S. pneumoniae infections have been available for several years, no vaccine is available at present against illnesses caused by RSV, PIV-3, metapneumovirus or any of the three novel coronaviruses. In addition, the threat constituted by the multiple outbreaks of avian influenza during the last few years is urgently calling for the development of new influenza vaccines with broader spectrum of efficacy, which could provide immunity against an avian influenza virus pandemic. This article reviews the state of the art in vaccine R&D against ARIs and attempts to address these basic public health questions.

Antimicrobial resistance determinants and future control

At the beginning of the 21st century, antimicrobial resistance is common, has developed against every class of antimicrobial drug, and appears to be spreading into new clinical niches. We describe determinants likely to influence the future epidemiology and health impact of antimicrobial-resistant infections. Understanding these factors will ultimately optimize preventive strategies for an unpredictable future.