Effect of pneumococcal conjugate vaccine on pneumococcal meningitis

Bacterial Meningitis in Brazil: Baseline Epidemiologic Assessment of the Decade Prior to the Introduction of Pneumococcal and Meningococcal Vaccines

BACKGROUND

Bacterial meningitis is associated with significant burden in Brazil. In 2010, both 10-valent pneumococcal conjugate vaccine and meningococcal capsular group C conjugate vaccine were introduced into the routine vaccination schedule. Haemophilus influenzae type b vaccine was previously introduced in 1999. This study presents trends in demographics, microbiological characteristics and seasonality patterns of bacterial meningitis cases in Brazil from 2000 to 2010.

METHODS AND FINDINGS

All meningitis cases confirmed by clinical and/or laboratory criteria notified to the national information system for notifiable diseases between 2000 and 2010 were analyzed. Proportions of bacterial meningitis cases by demographic characteristics, criteria used for confirmation and etiology were calculated. We estimated disease rates per 100,000 population and trends for the study period, with emphasis on H. influenzae, N. meningitidis and S. pneumoniae cases. In the decade, 341,805 cases of meningitis were notified in Brazil. Of the 251,853 cases with defined etiology, 110,264 (43.8%) were due to bacterial meningitis (excluding tuberculosis). Of these, 34,997 (31.7%) were due to meningococcal disease. The incidence of bacterial meningitis significantly decreased from 3.1/100,000 population in 2000-2002 to 2.14/100,000 in 2009-2010 (p<0.01). Among cases of meningococcal disease, the proportion of those associated with group C increased from 41% in 2007 to 61.7% in 2010, while the proportion of group B disease progressively declined. Throughout the study period, an increased number of cases occurred during winter.

CONCLUSIONS

Despite the reduction in bacterial meningitis incidence during the last decade, it remains a significant healthcare issue in Brazil. Meningococcal disease is responsible for the majority of the cases with group C the most common capsular type. Our study demonstrates the appropriateness of introduction of meningococcal vaccination in Brazil. Furthermore, this study provides a baseline for future evaluation of the impact of the vaccines introduction in Brazil and changes in disease epidemiology.

The changing epidemiology of childhood pneumococcal disease in Korea

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

Bacterial meningitis post-PCV7: declining incidence and treatment

The epidemiology of bacterial meningitis in the United States has changed tremendously in the past 20 years. Since the introduction of the Haemophilus influenzae type b vaccine in 1988, the incidence of H. influenzae type b meningitis has declined by at least 97%, and Streptococcus pneumoniae has emerged as the most common etiologic agent. The PCV7 (7-valent pneumococcal conjugate vaccine [Prevnar]; Wyeth Pharmaceuticals) vaccine, which targets 7 pneumococcal serotypes, was introduced in 2000 and has had an enormous impact on both the incidence and epidemiology of bacterial meningitis. This article reviews the impact of the PCV7 vaccine and the most up-to-date evidence on diagnosis and empiric therapy of suspected bacterial meningitis in the current day.

Central Nervous System Infections

Central nervous system (CNS) infections—i.e., infections involving the brain (cerebrum and cerebellum), spinal cord, optic nerves, and their covering membranes—are medical emergencies that are associated with substantial morbidity, mortality, or long-term sequelae that may have catastrophic implications for the quality of life of affected individuals. Acute CNS infections that warrant neurointensive care (ICU) admission fall broadly into three categories—meningitis, encephalitis, and abscesses—and generally result from blood-borne spread of the respective microorganisms. Other causes of CNS infections include head trauma resulting in fractures at the base of the skull or the cribriform plate that can lead to an opening between the CNS and the sinuses, mastoid, the middle ear, or the nasopharynx. Extrinsic contamination of the CNS can occur intraoperatively during neurosurgical procedures. Also, implanted medical devices or adjunct hardware (e.g., shunts, ventriculostomies, or external drainage tubes) and congenital malformations (e.g., spina bifida or sinus tracts) can become colonized and serve as sources or foci of infection. Viruses, such as rabies, herpes simplex virus, or polioviruses, can spread to the CNS via intraneural pathways resulting in encephalitis. If infection occurs at sites (e.g., middle ear or mastoid) contiguous with the CNS, infection may spread directly into the CNS causing brain abscesses; alternatively, the organism may reach the CNS indirectly via venous drainage or the sheaths of cranial and spinal nerves. Abscesses also may become localized in the subdural or epidural spaces. Meningitis results if bacteria spread directly from an abscess to the subarachnoid space. CNS abscesses may be a result of pyogenic meningitis or from septic emboli associated with endocarditis, lung abscess, or other serious purulent infections. Breaches of the blood–brain barrier (BBB) can result in CNS infections. Causes of such breaches include damage (e.g., microhemorrhage or necrosis of surrounding tissue) to the BBB; mechanical obstruction of microvessels by parasitized red blood cells, leukocytes, or platelets; overproduction of cytokines that degrade tight junction proteins; or microbe-specific interactions with the BBB that facilitate transcellular passage of the microorganism. The microorganisms that cause CNS infections include a wide range of bacteria, mycobacteria, yeasts, fungi, viruses, spirochaetes (e.g., neurosyphilis), and parasites (e.g., cerebral malaria and strongyloidiasis). The clinical picture of the various infections can be nonspecific or characterized by distinct, recognizable clinical syndromes. At some juncture, individuals with severe acute CNS infections require critical care management that warrants neuro-ICU admission. The implications for CNS infections are serious and complex and include the increased human and material resources necessary to manage very sick patients, the difficulties in triaging patients with vague or mild symptoms, and ascertaining the precise cause and degree of CNS involvement at the time of admission to the neuro-ICU. This chapter addresses a wide range of severe CNS infections that are better managed in the neuro-ICU. Topics covered include the medical epidemiology of the respective CNS infection; discussions of the relevant neuroanatomy and blood supply (essential for understanding the pathogenesis of CNS infections) and pathophysiology; symptoms and signs; diagnostic procedures, including essential neuroimaging studies; therapeutic options, including empirical therapy where indicated; and the perennial issue of the utility and effectiveness of steroid therapy for certain CNS infections. Finally, therapeutic options and alternatives are discussed, including the choices of antimicrobial agents best able to cross the BBB, supportive therapy, and prognosis.

Epidemiologic and clinical implications of second-generation pneumococcal conjugate vaccines

This review is based on published literature about some of the potential advantages and challenges of the second generation of pneumococcal conjugate vaccines, with special reference to 13-valent vaccine in children and adults.

Trends in the management of viral meningitis at United States children's hospitals

OBJECTIVE

To determine trends in the diagnosis and management of children with viral meningitis at US children's hospitals.

METHODS

We performed a multicenter cross sectional study of children presenting to the emergency department (ED) across the 41 pediatric tertiary-care hospitals participating in the Pediatric Health Information System between January 1, 2005, and December 31, 2011. A case of viral meningitis was defined by International Classification of Diseases, Ninth Revision, discharge diagnosis, and required performance of a lumbar puncture. We examined trends in diagnosis, antibiotic use, and resource utilization for children with viral meningitis over the study period.

RESULTS

We identified 7618 children with viral meningitis (0.05% of ED visits during the study period). Fifty-two percent of patients were <1 year of age, and 43% were female. The absolute number and the proportion of ED visits for children with viral meningitis declined from 0.98 cases per 1000 ED visits in 2005 to 0.25 cases in 2011 (P < .001). Most children with viral meningitis received a parenteral antibiotic (85%), and were hospitalized (91%). Overall costs for children for children with viral meningitis remain substantial (median cost per case $5056, interquartile range $3572-$7141).

CONCLUSIONS

Between 2005 and 2011, viral meningitis diagnoses at US children's hospitals declined. However, most of these children are hospitalized, and the cost for caring for these children remains considerable.

Preventing pneumococcal disease: intergenerational issues

In the United States, approximately four million people contract pneumococcal infections each year, and elders and children are at an increased risk of contracting these infections. Since the late 1800s, researchers have searched for a vaccine that covers the many serotypes of Streptococcus pneumoniae. Today, three vaccines are available, and each possesses subtle differences. Notwithstanding the positive impact from each vaccine type, the incidence of diseases caused by serotypes that are not included in specific vaccines tends to increase in children and certain adult populations with underlying illnesses. While these increases are usually small compared with the overall reduction in disease, some clinicians and patients question the effectiveness of vaccinations. Pharmacists need to promote pneumococcal vaccination and emphasize the need to also receive annual influenza vaccine.

Central nervous system infections among individuals with and without end-stage renal disease

OBJECTIVES

Individuals with immunodeficiencies are at increased risk of central nervous system (CNS) infections. Data are limited on the risk of CNS infections in patients with end-stage renal disease (ESRD).

METHODS

We conducted a population-based, nationwide cohort study among ESRD patients from 1990 to 2009. Data on ESRD patients was obtained from the Danish Nephrology Registry database. Each ESRD patient was matched with up to 19 population controls. Using the National Hospital Registry we identified hospital admissions with CNS infection as primary discharge diagnosis.

RESULTS

The study included 13,374 ESRD patients and 245,397 population controls, providing 67,012 person-years and 2,237,237 person-years of observation, respectively. The overall incidence rate (IR) of first-time hospitalisation for CNS infection was 149 per 100,000 person-years (95%-confidence interval [CI], 123-181) among ESRD patients. The IR of CNS infection was comparable among dialysis and transplant patients. Compared to population controls, the incidence rate-ratio of first CNS infection was 5.58 (95%-CI, 4.47-6.91) for ESRD patients in general. The 30-day mortality following hospitalisation for CNS infections was 21% (95%-CI, 14-30) among ESRD patients and 13% (95%-CI, 10-16) among population controls.

CONCLUSIONS

ESRD patients have considerable excess risk and mortality from CNS infections, which is of great clinical and public health concern.

Invasive Pneumococcal Infection Despite 7-Valent Conjugated Vaccine

Despite good cover with 7-valent vaccination, invasive pneumococcal infections may still be misdiagnosed and may lead to lifethreatening situations or death in young children. New serotypes are emerging and, therefore, clinicians must keep a high level of suspicion in young children regardless of their vaccination status. We report three cases of invasive pneumococcal infection due to new serotypes not covered by the 7-valent conjugated vaccine, two of which led children to death.

Characterization of protective immune responses induced by pneumococcal surface protein A in fusion with pneumolysin derivatives

Pneumococcal surface protein A (PspA) and Pneumolysin derivatives (Pds) are important vaccine candidates, which can confer protection in different models of pneumococcal infection. Furthermore, the combination of these two proteins was able to increase protection against pneumococcal sepsis in mice. The present study investigated the potential of hybrid proteins generated by genetic fusion of PspA fragments to Pds to increase cross-protection against fatal pneumococcal infection. Pneumolisoids were fused to the N-terminus of clade 1 or clade 2 pspA gene fragments. Mouse immunization with the fusion proteins induced high levels of antibodies against PspA and Pds, able to bind to intact pneumococci expressing a homologous PspA with the same intensity as antibodies to rPspA alone or the co-administered proteins. However, when antibody binding to pneumococci with heterologous PspAs was examined, antisera to the PspA-Pds fusion molecules showed stronger antibody binding and C3 deposition than antisera to co-administered proteins. In agreement with these results, antisera against the hybrid proteins were more effective in promoting the phagocytosis of bacteria bearing heterologous PspAs in vitro, leading to a significant reduction in the number of bacteria when compared to co-administered proteins. The respective antisera were also capable of neutralizing the lytic activity of Pneumolysin on sheep red blood cells. Finally, mice immunized with fusion proteins were protected against fatal challenge with pneumococcal strains expressing heterologous PspAs. Taken together, the results suggest that PspA-Pd fusion proteins comprise a promising vaccine strategy, able to increase the immune response mediated by cross-reactive antibodies and complement deposition to heterologous strains, and to confer protection against fatal challenge.

PspA family distribution, antimicrobial resistance and serotype of Streptococcus pneumoniae isolated from upper respiratory tract infections in Japan

Background

The protection against pneumococcal infections provided by currently available pneumococcal polysaccharide conjugate vaccines are restricted to the limited number of the serotypes included in the vaccine. In the present study, we evaluated the distribution of the pneumococcal capsular type and surface protein A (PspA) family of pneumococcal isolates from upper respiratory tract infections in Japan.

Methods

A total of 251 S. pneumoniae isolates from patients seeking treatment for upper respiratory tract infections were characterized for PspA family, antibiotic resistance and capsular type.

Results

Among the 251 pneumococci studied, the majority (49.4%) was identified as belonging to PspA family 2, while most of the remaining isolates (44.6%) belonged to family 1. There were no significant differences between the distributions of PspA1 versus PspA2 isolates based on the age or gender of the patient, source of the isolates or the isolates’ susceptibilities to penicillin G. In contrast, the frequency of the mefA gene presence and of serotypes 15B and 19F were statistically more common among PspA2 strains.

Conclusion

The vast majority of pneumococci isolated from the middle ear fluids, nasal discharges/sinus aspirates or pharyngeal secretions represented PspA families 1 and 2. Capsular serotypes were generally not exclusively associated with certain PspA families, although some capsular types showed a much higher proportion of either PspA1 or PspA2. A PspA-containing vaccine would potentially provide high coverage against pneumococcal infectious diseases because it would be cross-protective versus invasive disease with the majority of pneumococci infecting children and adults.

Nanogel-based PspA intranasal vaccine prevents invasive disease and nasal colonization by Streptococcus pneumoniae

To establish a safer and more effective vaccine against pneumococcal respiratory infections, current knowledge regarding the antigens common among pneumococcal strains and improvements to the system for delivering these antigens across the mucosal barrier must be integrated. We developed a pneumococcal vaccine that combines the advantages of pneumococcal surface protein A (PspA) with a nontoxic intranasal vaccine delivery system based on a nanometer-sized hydrogel (nanogel) consisting of a cationic cholesteryl group-bearing pullulan (cCHP). The efficacy of the nanogel-based PspA nasal vaccine (cCHP-PspA) was tested in murine pneumococcal airway infection models. Intranasal vaccination with cCHP-PspA provided protective immunity against lethal challenge with Streptococcus pneumoniae Xen10, reduced colonization and invasion by bacteria in the upper and lower respiratory tracts, and induced systemic and nasal mucosal Th17 responses, high levels of PspA-specific serum immunoglobulin G (IgG), and nasal and bronchial IgA antibody responses. Moreover, there was no sign of PspA delivery by nanogel to either the olfactory bulbs or the central nervous system after intranasal administration. These results demonstrate the effectiveness and safety of the nanogel-based PspA nasal vaccine system as a universal mucosal vaccine against pneumococcal respiratory infection.

Serotype-specific changes in invasive pneumococcal disease after pneumococcal conjugate vaccine introduction: a pooled analysis of multiple surveillance sites

BACKGROUND

Vaccine-serotype (VT) invasive pneumococcal disease (IPD) rates declined substantially following introduction of 7-valent pneumococcal conjugate vaccine (PCV7) into national immunization programs. Increases in non-vaccine-serotype (NVT) IPD rates occurred in some sites, presumably representing serotype replacement. We used a standardized approach to describe serotype-specific IPD changes among multiple sites after PCV7 introduction.

METHODS AND FINDINGS

Of 32 IPD surveillance datasets received, we identified 21 eligible databases with rate data ≥ 2 years before and ≥ 1 year after PCV7 introduction. Expected annual rates of IPD absent PCV7 introduction were estimated by extrapolation using either Poisson regression modeling of pre-PCV7 rates or averaging pre-PCV7 rates. To estimate whether changes in rates had occurred following PCV7 introduction, we calculated site specific rate ratios by dividing observed by expected IPD rates for each post-PCV7 year. We calculated summary rate ratios (RRs) using random effects meta-analysis. For children <5 years old, overall IPD decreased by year 1 post-PCV7 (RR 0.55, 95% CI 0.46-0.65) and remained relatively stable through year 7 (RR 0.49, 95% CI 0.35-0.68). Point estimates for VT IPD decreased annually through year 7 (RR 0.03, 95% CI 0.01-0.10), while NVT IPD increased (year 7 RR 2.81, 95% CI 2.12-3.71). Among adults, decreases in overall IPD also occurred but were smaller and more variable by site than among children. At year 7 after introduction, significant reductions were observed (18-49 year-olds [RR 0.52, 95% CI 0.29-0.91], 50-64 year-olds [RR 0.84, 95% CI 0.77-0.93], and ≥ 65 year-olds [RR 0.74, 95% CI 0.58-0.95]).

CONCLUSIONS

Consistent and significant decreases in both overall and VT IPD in children occurred quickly and were sustained for 7 years after PCV7 introduction, supporting use of PCVs. Increases in NVT IPD occurred in most sites, with variable magnitude. These findings may not represent the experience in low-income countries or the effects after introduction of higher valency PCVs. High-quality, population-based surveillance of serotype-specific IPD rates is needed to monitor vaccine impact as more countries, including low-income countries, introduce PCVs and as higher valency PCVs are used. Please see later in the article for the Editors' Summary.

Clinical implications of pneumococcal serotypes: invasive disease potential, clinical presentations, and antibiotic resistance

Streptococcus pneumoniae can asymptomatically colonize the nasopharynx and cause a diverse range of illnesses. This clinical spectrum from colonization to invasive pneumococcal disease (IPD) appears to depend on the pneumococcal capsular serotype rather than the genetic background. According to a literature review, serotypes 1, 4, 5, 7F, 8, 12F, 14, 18C, and 19A are more likely to cause IPD. Although serotypes 1 and 19A are the predominant causes of invasive pneumococcal pneumonia, serotype 14 remains one of the most common etiologic agents of non-bacteremic pneumonia in adults, even after 7-valent pneumococcal conjugate vaccine (PCV7) introduction. Serotypes 1, 3, and 19A pneumococci are likely to cause empyema and hemolytic uremic syndrome. Serotype 1 pneumococcal meningitis is prevalent in the African meningitis belt, with a high fatality rate. In contrast to the capsule type, genotype is more closely associated with antibiotic resistance. CC320/271 strains expressing serotype 19A are multidrug-resistant (MDR) and prevalent worldwide in the era of PCV7. Several clones of MDR serotype 6C pneumococci emerged, and a MDR 6D clone (ST282) has been identified in Korea. Since the pneumococcal epidemiology of capsule types varies geographically and temporally, a nationwide serosurveillance system is vital to establishing appropriate vaccination strategies for each country.

Changes in molecular epidemiology of streptococcus pneumoniae causing meningitis following introduction of pneumococcal conjugate vaccination in England and Wales

The introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in September 2006 has markedly reduced the burden of invasive pneumococcal disease (IPD) including meningitis in England and Wales. This study examined changes in the molecular epidemiology of pneumococcal isolates causing meningitis from July 2004 to June 2009. The Health Protection Agency conducts enhanced pneumococcal surveillance in England and Wales. In addition to serotyping, pneumococcal isolates causing meningitis were genotyped by multilocus sequence typing (MLST). A total of 1,030 isolates were both serotyped and genotyped over the 5-year period. Fifty-two serotypes, 238 sequence types (STs), and 87 clonal complexes were identified, with no significant difference in the yearly Simpson's diversity index values (range, 0.974 to 0.984). STs commonly associated with PCV7 serotypes declined following PCV implementation, with a proportionally greater decline in ST124 (commonly associated with serotype 14). No other ST showed significant changes in distribution, even within individual serotypes. Replacement disease following PCV7 introduction was mainly due to serotypes 1, 3, 7F, 19A, 22F, and 33F through clonal expansion. A single instance of possible capsule switching was identified where one ST4327 clone expressed a serotype 14 capsule in 2005 and a serotype 28A capsule in 2009. In 2008 to 2009, ST191 (7F) became the most prevalent clone causing meningitis (10.3%). Case fatality (145 fatalities/1,030 cases; 14.1%) was high across all age groups and serotype groups. Thus, the introduction of PCV7 resulted in an increase in non-PCV7 serotypes, including some not covered by the 13-valent vaccine, such as serotypes 22F and 33F, emphasizing the importance of long-term epidemiological and molecular surveillance.

Pharmacotherapy for pneumococcal infections: an update

INTRODUCTION

The management of pneumococcal diseases still places a significant burden on medical and economic resources. The subjects at greatest risk of pneumococcal infections are children.

AREAS COVERED

The aim of this review is to analyse the best current therapeutic approach to pneumococcal resistance, taking into account the level of susceptibility of Streptococcus pneumoniae, and the pharmacokinetics and pharmacodynamics of different antibiotics in the various pneumococcal diseases.

EXPERT OPINION

Antibiotic treatment of a number of pneumococcal diseases remains difficult or impossible due to the presence of strains resistant to commonly used antibiotics. In children the problem is significantly more important than in adults due to the reduced number of licenced drugs for subjects in the first years of life. The new conjugate pneumococcal vaccines containing 10 (PCV10) and 13 serotypes (PCV13), which include most of the recently emerging strains, might reduce the incidence of pneumococcal infections and the circulation of resistant pathogens. However, it is likely that optimal results will only be reached after the development of effective vaccines based on conserved proteins that are capable of preventing all pneumococcal infections, regardless of the serotype of the causative organism.

Revisão sistemática do uso da dexametasona como terapia adjuvante na meningite bacteriana em crianças

OBJETIVO: Analisar a melhor evidência disponível nos últimos 15 anos com relação aos benefícios da terapia adjuvante com dexametasona na meningite bacteriana em população pediátrica. FONTES DE DADOS: Das bases de dados Medline, Lilacs e SciELO, foram analisados ensaios clínicos randomizados de 1996 a 2011, os quais comparavam a dexametasona ao placebo e/ou a outra terapia adjuvante em pacientes com meningite bacteriana diagnosticada laboratorialmente por critérios quimiocitológicos e/ou bacteriológicos, na faixa etária de 29 dias aos 18 anos. Os desfechos avaliados foram mortalidade e ocorrência de sequelas neurológicas e/ou auditivas. Foram excluídos estudos relacionados à meningite tuberculosa. SÍNTESE DOS DADOS: Com os critérios utilizados, foram identificadas cinco publicações correspondentes a quatro protocolos de estudo. Nenhum dos estudos mostrou diferenças entre a dexametasona e o placebo para os desfechos avaliados. Os estudos analisados tiveram alta qualidade (escore de Jadad et al=5). CONCLUSÕES: As evidências encontradas na literatura são insuficientes para indicar de forma rotineira o uso da dexametasona como terapia adjuvante para redução de mortalidade, perda auditiva e sequelas neurológicas em pacientes pediátricos com meningite bacteriana não tuberculosa.

Advances in treatment of bacterial meningitis

Bacterial meningitis kills or maims about a fifth of people with the disease. Early antibiotic treatment improves outcomes, but the effectiveness of widely available antibiotics is threatened by global emergence of multidrug-resistant bacteria. New antibiotics, such as fluoroquinolones, could have a role in these circumstances, but clinical data to support this notion are scarce. Additionally, whether or not adjunctive anti-inflammatory therapies (eg, dexamethasone) improve outcomes in patients with bacterial meningitis remains controversial; in resource-poor regions, where the disease burden is highest, dexamethasone is ineffective. Other adjunctive therapeutic strategies, such as glycerol, paracetamol, and induction of hypothermia, are being tested further. Therefore, bacterial meningitis is a substantial and evolving therapeutic challenge. We review this challenge, with a focus on strategies to optimise antibiotic efficacy in view of increasingly drug-resistant bacteria, and discuss the role of current and future adjunctive therapies.

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

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

Risk factors for multidrug-resistant invasive pneumococcal disease in South Africa, a setting with high HIV prevalence, in the prevaccine era from 2003 to 2008

The emergence of multidrug-resistant (MDR) Streptococcus pneumoniae complicates disease management. We aimed to determine risk factors associated with MDR invasive pneumococcal disease (IPD) in South Africa and evaluate the potential for vaccination to reduce disease burden. IPD data collected by laboratory-based surveillance from 2003 through 2008 were analyzed. Multidrug resistance was defined as nonsusceptibility to any three or more different antibiotic classes. Risk factors for multidrug resistance were evaluated using multivariable logistic regression. Of 20,100 cases of IPD identified, 3,708 (18%) had MDR isolates, with the proportion increasing from 16% (461/2,891) to 20% (648/3,326) (P < 0.001) over the study period. Serotypes included in the 13-valent pneumococcal conjugate vaccine (PCV13) accounted for 94% of MDR strains. Significant risk factors for MDR IPD included PCV13 (1,486/6,407; odds ratio [OR] of 6.3; 95% confidence interval [CI] of 5.0 to 7.9) and pediatric (3,382/9,980; OR of 12.8; 95% CI of 10.6 to 15.4) serotypes, age of <5 (802/3,110; OR of 2.0; 95% CI of 1.8 to 2.3) or ≥65 (39/239; OR of 1.5; 95% CI of 1.0 to 2.2) years versus age of 15 to 64 years, HIV infection (975/4,636; OR of 1.5; 95% CI of 1.2 to 1.8), previous antibiotic use (242/803; OR of 1.7; 95% CI of 1.4 to 2.1), previous hospital admissions (579/2,450; OR of 1.2; 95% CI of 1.03 to 1.4), urban location (883/4,375; OR of 2.0; 95% CI of 1.1 to 3.5), and tuberculosis treatment (246/1,021; OR of 1.2; 95% CI of 1.03 to 1.5). MDR IPD prevalence increased over the study period. The effect of many of the MDR risk factors could be reduced by more judicious use of antibiotics. Because PCV13 serotypes account for most MDR infections, pneumococcal vaccination may reduce the prevalence of multidrug resistance.

Laboratory surveillance of invasive pneumococcal disease in New South Wales, Australia, before and after introduction of 7-valent conjugate vaccine: reduced disease, but not antibiotic resistance rates

We compared serotype distributions of Streptococcus pneumoniae isolates from patients aged <5 and o5 years with invasive pneumococcal disease in New South Wales, Australia, and antibiotic susceptibilities of isolates from the <5 years age group only, before (2002–2004) and after(2005–2009) introduction of the 7-valent pneumococcal conjugate vaccine (PCV7). Overall, there were significant decreases in the mean annual number of referred isolates (770 vs. 515) and the proportion belonging to PCV7 serotypes (74% vs. 38%), but non-PCV7 serotypes, particularly 19A, increased (5% vs. 18%). All changes were more marked in the <5 years age group.Susceptibility testing of isolates from the <5 years age group showed variation in resistance between serotypes, but significant overall increases in penicillin non-susceptibility (23% vs. 31%),ceftriaxone resistance (2% vs. 12%) and multidrug resistance (4% vs. 7%) rates ; erythromycin resistance fell (32% vs. 25%). Continued surveillance is needed to monitor changes following the introduction of 13-valent PCV in 2012.

Future challenges in the elimination of bacterial meningitis

Despite the widespread implementation of several effective vaccines over the past few decades, bacterial meningitis caused by Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis and Group B Streptococcus (GBS) still results in unacceptably high levels of human mortality and morbidity. A residual disease burden due to bacterial meningitis is also apparent due to a number of persistent or emerging pathogens, including Mycobacterium tuberculosis, Escherichia coli, Staphylococcus aureus, Salmonella spp. and Streptococcus suis. Here, we review the current status of bacterial meningitis caused by these pathogens, highlighting how past and present vaccination programs have attempted to counter these pathogens. We discuss how improved pathogen surveillance, implementation of current vaccines, and development of novel vaccines may be expected to further reduce bacterial meningitis and related diseases in the future.

Clinical and microbiological epidemiology of Streptococcus pneumoniae bacteremia in cancer patients

OBJECTIVES

In the current era of changing epidemiology of invasive pneumococcal disease, we aimed to assess the clinical features, antimicrobial susceptibility, vaccination status, serotypes, genotypes and outcomes of pneumococcal bacteremia in cancer patients.

METHODS

Prospective observational analysis of all consecutive cancer adults admitted to a university hospital (January 2006-April 2011).

RESULTS

Of 971 episodes of bacteremia, 63 (6.5%) were caused by Streptococcus pneumoniae. Pneumonia was the most common source of pneumococcal bacteremia (84.1%). Although all isolated pneumococci were penicillin-susceptible, resistance to ceftazidime was high (43%). The serotypes most frequently isolated were 19A and 14, and the most common genotypes were Spain(9V)-ST156 and Denmark(14)-ST230. Only 23% of patients had received the 23-valent polysaccharide pneumococcal vaccine. This polysaccharide vaccine was found to cover 72.4% of the serotypes identified, whereas the 7-valent, 10-valent and the 13-valent conjugate vaccines covered 24.1%, 29.3%, and 53.5% of serotypes respectively. The early case-fatality rate (<48 h) was 4.8% and overall case-fatality rate (<30 days) 14.3%.

CONCLUSIONS

Pneumococcal bacteremia, which complicates mainly pneumonia, is frequent in cancer patients and causes significant morbidity and case-fatality rate. Resistance to ceftazidime is particularly high. These findings should be considered when selecting antibiotic treatment for cancer patients presenting pneumonia.

Eradication of invasive pneumococcal disease due to the seven-valent pneumococcal conjugate vaccine serotypes in Calgary, Alberta

BACKGROUND

The seven-valent pneumococcal conjugate vaccine (PCV7) was licensed in Canada in 2001. Routine infant vaccination programs in Alberta began in 2002. Several years after PCV7 introduction, the routine use of PCV7 in infants and high-risk children has led to near elimination of invasive pneumococcal disease (IPD) caused by vaccine serotypes.

METHODS

Prospective, population-based surveillance of all IPD cases was conducted from January 1998 to December 2010. Demographic, clinical and microbiologic data were collected.

RESULTS

There were 1462 IPD cases over 13 years. Comparing PCV7 serotype IPD incidence in the prevaccine period (1998-2001) to the late postvaccine period (2007-2010), there were declines in children 0-5 months (100%), 6-23 months (98%), 2-4 years (97%), 5-15 years (100%) as well as in adults 16-64 years (73%), 65-84 years (90%) and ≥85 years of age (100%). From 2008 to 2010, there were no cases of PCV7 serotype IPD in children under 2 years of age. There have been increases in non-PCV7 serotype IPD; notably, serotypes 5 and 19A have increased significantly in adults and 19A in children.

CONCLUSIONS

PCV7 serotype IPD has been eliminated in vaccine-eligible young children and nearly eliminated in all other age groups. Serotype 19A increased significantly at all ages before the introduction of an expanded valency pneumococcal conjugate vaccine.

Invasive pneumococcal disease in healthy adults: increase of empyema associated with the clonal-type Sweden(1)-ST306

Background

Adult invasive pneumococcal disease (IPD) occurs mainly in the elderly and patients with co-morbidities. Little is known about the clinical characteristics, serotypes and genotypes causing IPD in healthy adults.

Methods

We studied 745 culture-proven cases of IPD in adult patients aged 18–64 years (1996–2010). Patients were included in two groups: 1.) adults with co-morbidities, and 2.) healthy adults, who had no prior or coincident diagnosis of a chronic or immunosuppressive underlying disease. Microbiological studies included pneumococcal serotyping and genotyping.

Results

Of 745 IPD episodes, 525 (70%) occurred in patients with co-morbidities and 220 (30%) in healthy adults. The healthy adults with IPD were often smokers (56%) or alcohol abusers (18%). As compared to patients with co-morbidities, the healthy adults had (P<0.05): younger age (43.5+/−13.1 vs. 48.7+/−11.3 years); higher proportions of women (45% vs. 24%), pneumonia with empyema (15% vs. 7%) and infection with non-PCV7 serotypes including serotypes 1 (25% vs. 5%), 7F (13% vs. 4%), and 5 (7% vs. 2%); and lower mortality (5% vs. 20%). Empyema was more frequently caused by serotype 1. No death occurred among 79 patients with serotype 1 IPD. There was an emergence of virulent clonal-types Sweden¹-ST306 and Netherlands^7F-ST191. The vaccine serotype coverage with the PCV13 was higher in healthy adults than in patients with co-morbidities: 82% and 56%, respectively, P<0.001.

Conclusion

In this clinical study, one-third of adults with IPD had no underlying chronic or immunosuppressive diseases (healthy adults). They were often smokers and alcohol abusers, and frequently presents with pneumonia and empyema caused by virulent clones of non-PCV7 serotypes such as the Sweden¹-ST306. Thus, implementing tobacco and alcohol abuse-cessation measures and a proper pneumococcal vaccination, such as PCV13 policy, in active smokers and alcohol abusers may diminish the burden of IPD in adults.

Epidemiology of central nervous system infection

In cases of central nervous system infection, it is crucial for the neuroradiologist to provide an accurate differential diagnosis of the possible pathogens involved so that treating physicians can be aided in the choice of empiric therapy. This approach requires the radiologist to be aware of local epidemiology and have knowledge of infectious agents that are endemic to their area of practice. This article reviews and discusses the changing epidemiology of pathogens most often observed in meningitis, brain abscess, epidural abscess, postoperative infections, and human immunodeficiency virus infection.

Developing vaccines in the era of genomics: a decade of reverse vaccinology

Vaccines have a significant impact on public health, and vaccinology in the era of genomics is taking advantage of new technologies to tackle diseases for which vaccine development has so far been unsuccessful. Almost all existing vaccines were developed based on traditional vaccinology methods, which relied on empirical screening of a few candidates at a time, based on known features of the pathogen. However, the ability to sequence a pathogen's genome provides access to its entire antigenic repertoire. As such, genomics has catalysed a shift in vaccine development towards sequence-based 'Reverse Vaccinology' approaches, which use high-throughput in silico screening of the entire genome of a pathogen to identify genes that encode proteins with the attributes of good vaccine targets. Furthermore, the increasing availability of genome sequences has led to the development and application of additional technologies to vaccine discovery, including comparative genomics, transcriptomics, proteomics, immunomics and structural genomics. Vaccine candidates identified from a pathogen's genome or proteome can then be expressed as recombinant proteins and tested in appropriate in vitro or in vivo models to assess immunogenicity and protection. The process of reverse vaccinology has been applied to several pathogens, including serogroup B Neisseria meningitidis, Streptococcus agalactiae, Streptococcus pyogenes, Streptococcus pneumoniae and pathogenic Escherichia coli, and has provided scores of new candidate antigens for preclinical and clinical investigation. As novel genome-based technologies continue to emerge, it is expected that new vaccines for unmet diseases will be within reach.

Pneumococcal vaccines for children: a global public health priority

Pneumococcal conjugated vaccines have been recommended in children for over a decade in many countries worldwide. Here we review the development of pneumococcal vaccines with a focus on the two types currently available for children and their safety record. We discuss also the effect of vaccines, including the 13-valent pneumococcal conjugate vaccine, on invasive pneumococcal diseases in children, particularly bacteraemia, pneumonia and meningitis, as well as on mucosal disease and carriage. In regions where immunization was implemented in young children, the number of invasive pneumococcal diseases decreased significantly, not only in the target age group, but also in younger and much older subjects. Challenges and future perspectives regarding the development of new 'universal' vaccines, which could bypass the current problem of serotype-specific protection in a context of serotype replacement, are also discussed.

Four years of universal pneumococcal conjugate infant vaccination in Germany: impact on incidence of invasive pneumococcal disease and serotype distribution in children

INTRODUCTION

Vaccination with pneumococcal conjugate vaccine (PCV) for all children <2 years was recommended in Germany in July 2006. Initially PCV7 was exclusively used; PCV10 became available from April 2009 and PCV7 was replaced by PCV13 in December 2009.

OBJECTIVE

To compare the incidence and serotype distribution of invasive pneumococcal disease (IPD) for pneumococcal meningitis and non-meningitis IPD in children from 2007 to 2010 with reference to the pre-vaccination period from 1997 to 2001.

METHODS

Nationwide surveillance of IPD for children <16 years in Germany was based on two independent reporting sources: active surveillance in paediatric hospitals and passive web-based surveillance through microbiological laboratories. Serotyping was performed using the Neufeld Quellung reaction.

CASE DEFINITION

isolation of Streptococcus pneumoniae from a normally sterile body site. IPD incidence was estimated by capture-recapture analysis. Rate ratios comparing post- to pre-vaccination incidence were calculated as well as PCV7 and non-PCV7 serotype specific incidences.

RESULTS

While PCV7 incidence decreased by 88% (95%CI: 83 to 91) in children <16 years both in pneumococcal meningitis and non-meningitis IPD, an increase in Non-PCV7 serotypes was observed which was more pronounced in non-meningitis cases (168%; 95%CI: 140-257) than in pneumoccocal meningitis (65%; 95%CI: 23-123). The changes in incidence after four years were: <16 years: -35% (95%CI: -49 to -19), <2 years: -46% (95%CI: -61 to -27) for pneumococcal meningitis and+11% (95%CI: -4 to +29) and -26% (95%CI: -41 to -7) for non-meningitis IPD respectively.

CONCLUSION

Infant PCV7 vaccination in Germany prompted a decrease in the incidence of pneumococcal meningitis similar to that observed in England/Wales. In non-meningitis IPD the decrease was smaller and confined to the age group <2 years with no change or an increase in incidence in other age groups pointing to potential ascertainment bias due to increased blood-culturing.

Serotype and clonal evolution of penicillin-nonsusceptible invasive Streptococcus pneumoniae in the 7-valent pneumococcal conjugate vaccine era in Italy

The percentage of invasive penicillin-nonsusceptible pneumococci (PNSSP) isolated in Italy in the seven-valent pneumococcal conjugate vaccine (PCV7) era moderately increased in comparison to the pre-PCV7 era. Increase of nonvaccine serotypes was observed among PNSSP. The most frequent PNSSP clones were the same as those identified in the pre-PCV7 era, although they were present in different proportions. Clonal expansion, emergence of new clones, and acquisition of penicillin resistance by established clones contributed to the maintenance of penicillin resistance.

Toward a meningitis-free world

Meningococcal meningitis is a devastating disease that is often fatal. Vaccines against the five major meningococcal serogroups causing disease are about to become available, a conjugate vaccine against meningococcus A is in use for mass vaccination in Africa, and a protein-based vaccine against meningococcal B is ready for licensure. With the availability of these new vaccines, the world can finally be rid of meningococcal meningitis, thus rewriting a new chapter in medical history.

Streptococcus pneumoniae serotype 19A in Latin America and the Caribbean: a systematic review and meta-analysis, 1990-2010

BACKGROUND

Pneumococcal conjugate vaccines (PCVs) are in the process of implementation in Latin America. Experience in developed countries has shown that they reduce the incidence of invasive and non-invasive disease. However, there is evidence that the introduction of PCVs in universal mass vaccination programs, combined with inappropriate and extensive use of antibiotics, could be associated to changes in non-PCV serotypes, including serotype 19A. We conducted a systematic review to determine the distribution of serotype 19A, burden of pneumococcal disease and antibiotic resistance in the region.

METHODS

We performed a systematic review of serotype 19A data from observational and randomized clinical studies in the region, conducted between 1990 and 2010, for children under 6 years. Pooled prevalence estimates from surveillance activities with confidence intervals were calculated.

RESULTS

We included 100 studies in 22 countries and extracted data from 63. These data reported 19733 serotyped invasive pneumococcal isolates, 3.8% of which were serotype 19A. Serotype 19A isolates were responsible for 2.4% acute otitis media episodes, and accounted for 4.1% and 4.4% of 4,380 nasopharyngeal isolates from healthy children and in hospital-based/sick children, respectively. This serotype was stable over the twenty years of surveillance in the region. A total of 53.7% Spn19A isolates from meningitis cases and only 14% from non meningitis were resistant to penicillin.

CONCLUSIONS

Before widespread PCV implementation in this region, serotype 19A was responsible for a relatively small number of pneumococcal disease cases. With increased use of PCVs and a greater number of serotypes included, monitoring S. pneumoniae serotype distribution will be essential for understanding the epidemiology of pneumococcal disease.

A Pneumococcal Carriage Study in Danish Pre-school Children before the Introduction of Pneumococcal Conjugate Vaccination

We present data on pneumococcal carriage before the introduction of the heptavalent-pneumococcal conjugated vaccine (PCV7) in Denmark. In the pre-PCV7 period, the incidence of invasive pneumococcal disease (IPD) among children younger than 5 years was approximately 25 per 100.000 population, with the highest incidence rates observed in children younger than 2 years of age. The study included 437 children aged 12-72 months attending day care centres (DCC) and was conducted during 48 months. In total, 56% (n=247) of children were pneumococcal carriers with the highest prevalence in children aged 12–23 months (69%), the proportion significantly declining with increasing age. PCV7 serotypes accounted for 33%, PCV10 for 34%, and PCV13 for 57% of all carried isolates. The proportion of serotypes included in the three conjugate vaccines was higher among IPD isolates compared to carrier isolates (range 35– 90%). We found that the frequency of carriage was high among Danish pre-school children attending DCC and serotypes were not frequently covered by PCV7 in the pre-PCV7 period.

Invasive pneumococcal disease in infants younger than 60 days

OBJECTIVE

To review the epidemiology and clinical course of invasive pneumococcal diseases of infants younger than 60 days.

STUDY DESIGN

All Streptococcus pneumoniae strains isolated from blood and cerebrospinal fluid cultures of infants below the age of 60 days during the years 1999-2009 were included in this study. Demographic, clinical, and laboratory data were collected from medical records.

RESULTS

In all, 24 cases of pneumococcal invasive infections were identified. The primary diagnoses were bacteremia without a focus (n = 13), meningitis (n = 6), bacteremia with otitis media (n = 3), and joint infection with bacteremia (n = 2). Only one of the serotypes found is included in the heptavalent pneumococcal conjugated vaccine (PCV7).

CONCLUSIONS

Streptococcus pneumoniae should be considered and treated empirically in infants with suspected invasive bacterial disease during the first 60 days of life. Routine vaccination with PCV7 in not expected to substantially reduce the incidence of invasive pneumococcal disease in Israeli infants of this age as a result of herd immunity.

The changing epidemiology of invasive pneumococcal disease at a tertiary children's hospital through the 7-valent pneumococcal conjugate vaccine era: a case for continuous surveillance

BACKGROUND

In 2000, a 7-valent pneumococcal conjugate vaccine (PCV7) was licensed for use among US children. Many sites have since reported changes in invasive pneumococcal disease (IPD). We recognized an opportunity to describe the changes in epidemiology, clinical syndromes, and serotype distribution during a 14-year period including 4 years before vaccine introduction and spanning the entire PCV7 era.

METHODS

Cases were defined as children <18 years of age who were cared for at Primary Children's Medical Center for culture-confirmed IPD. We defined the prevaccine period as the time frame spanning from 1997 to 2000 and the postvaccine period from 2001 to 2010. Demographics, clinical data, and outcomes were collected through electronic query and chart review. Streptococcus pneumoniae serotyping was performed using the capsular swelling method.

RESULTS

The median age of children with IPD increased from 19 months during the prevaccine period to 27 months during postvaccine period (P = 0.02), with a larger proportion of IPD among children older than 5 years. The proportion of IPD associated with pneumonia increased substantially from 29% to 50% (P < 0.001). This increase was primarily attributable to an increase in complicated pneumonia (17% to 33%, P < 0.001). Nonvaccine serotypes 7F, 19A, 22F, and 3 emerged as the dominant serotypes in the postvaccine period. In children with IPD who were younger than 5 years, for whom vaccine is recommended, 67% of the cases were caused by serotypes in 13-valent PCV during 2005 to 2010.

CONCLUSIONS

After PCV7 was introduced, significant changes in IPD were noted. One-third of IPD occurred in children older than 5 years, who were outside the age-group for which PCV is recommended. Continued surveillance is warranted to identify further evolution of the epidemiology, clinical syndromes, and serotype distribution of S. pneumoniae after 13-valent PCV licensure.

A challenge to appropriate antibiotic use in children with respiratory infections: a 5-year single-institution experience

BACKGROUND

We have studied the rate of emergence of antibiotic-resistant Streptococcus pneumoniae (S. pneumoniae) and Haemophilus influenzae (H. influenzae) and the subsequent antibiotic use in host patients of those isolates at the Department of Pediatrics, Soma General Hospital, Fukushima. Moreover, we carried out several studies investigating the risks and benefits of antibiotic-free treatment for children with respiratory infections. In this report, we summarize our research and suggest better treatment options for pediatric patients with respiratory infections.

METHODS

We investigated the necessity of antibiotic use in the treatment of pediatric inpatients with respiratory syncytial virus (RSV) infection, and tested our hypothesis that antibiotic-free treatment for common cold will reduce the number of resistant S. pneumoniae strains in the pediatric nasopharynx. Therefore, we restricted prescribing antibiotics for pediatric patients with respiratory infections. The rates of resistant S. pneumoniae and H. influenzae and the medication history of the host patients before and after the intervention were compared.

RESULTS

We found that most of the RSV-infected patients recovered without antibiotic treatment, and that the antibiotic-free treatment inhibited the emergence of antibiotic-resistant strains. The rate of penicillin-resistant S. pneumoniae decreased but the rate of ampicillin-resistant H. influenzae did not change significantly during the study.

CONCLUSION

We concluded that patients with respiratory infections can be treated without antibiotics, under careful examination and observation. Continued monitoring of such new interventions as well as recommending their use to other caregivers and physicians will help inhibit the spread of resistant strains.

Immune Responses to pneumococcal vaccines in children and adults: Rationale for age-specific vaccination

Streptococcus pneumoniae is a significant human pathogen and currently available pneumococcal vaccines are designed to elicit anti-capsule antibodies. The 23-valent polysaccharide vaccine has been used in older adults for many years whereas 7-, 10-, and 13-valent pneumococcal conjugate vaccines have only been used commonly for young children in the last decade. In addition to their high protective efficacy among children, the use of conjugate vaccines in young children has had a number of additional effects, including production of a serotype shift and providing new herd immunity to adults. The immunogenicity of both of these types of vaccines can be determined by using an ELISA assay to measure antibody levels or an opsonophagocytosis assay to assess opsonic function. As these assays have improved over time, awareness of the analytical limitations of older studies has grown. While the 23-valent vaccine is effective among young adults, it is less effective among elderly adults. Aging-associated ineffectiveness may be due to aging-dependent changes in the antibody repertoire and/or a reduction in IgM antibody production associated with aging-dependent changes in B cell subpopulations. The immunologic basis of aging-associated immune defects thus remains an active area of research.

The pharmacoeconomics of pneumococcal conjugate vaccines in Latin America

Streptococcus pneumoniae continues to be the most important causative agent of invasive bacterial infections in children and is the most common cause of vaccine-preventable deaths in children less than 5 years of age. Due to some conditions in the Latin America region, economic assessments of pneumococcal conjugate vaccines (PCVs) have unique characteristics. First, distribution of S. pneumoniae serotypes, and thus coverage by vaccines that incorporate certain serotypes, varies within the region and compared with other parts of the world. Second, the mortality rate of pneumococcal infections in developing countries is significantly higher than in the US and Europe. Third, the economies of the Latin American region are very different from those of developed countries. For these reasons, the Pan American Health Organization (PAHO) is promoting the need for economic valuation studies of the impact of pneumococcal vaccines Latin America. Given the importance of pneumonia in the burden of pneumococcal disease in Latin America, the number of pneumonia cases prevented by the vaccine has a large impact on the economic valuation of PCVs, due to a strong correlation with numbers of deaths averted, quality-adjusted life-years (QALYs) gained or disability-adjusted life-years (DALYs) avoided. In terms of cost, analysis of impact on acute otitis media (short-term) and sequelae (long-term) show a significant and important expenditure avoided by vaccination. Cost-effectiveness is significantly modified by vaccine cost, mortality due to pneumonia, vaccine efficacy/effectiveness and herd immunity. Finally the validity of certain assumptions based on the uncertainty of the data should be considered in economic assessments of new PCVs. These include assumptions related to the impact on otitis media, estimates of efficacy/effectiveness based on measured antibody levels and the extrapolation to PCV10 and PCV13 of previous experience with PCV7.

Pneumococcal disease manifestation in children before and after vaccination: what's new?

Pneumococcal infections remain a relevant cause of morbidity and mortality in children, especially in countries where vaccination has not been introduced. In contrast to the common belief by many pediatricians, the most important pneumococcal infections are of the respiratory tract and not invasive diseases. The recent pandemic of the H1N1 virus prompted studies to better understand the interaction between the influenza virus, Streptococcus pneumoniae, and pneumonia outcomes. Radiological findings of bacteremic pneumonia have been well investigated and besides the typical alveolar consolidation, a broad spectrum of atypical patterns has been reported. Molecular techniques, such as real-time polymerase chain reaction (PCR), can improve the detection of S. pneumoniae in sterile fluids, mainly in regions where previous antibiotic therapy is a common practice. In the post vaccination era, new manifestations of pneumococcal invasive disease, such as hemolytic uremic syndrome, have increased in association with parapneumonic empyema. Moreover, serotypes not included in PCV7, particularly serotypes 1, 3, 5, 7F, and 19A, have been among the most common isolates in pneumococcal disease. In Latin America, pneumococcal primary peritonitis has been described as an important clinical syndrome in a growing proportion of patients, mainly in girls. The development of newer and more specific diagnostic markers to distinguish bacterial and viral pneumonia are urgently sought, and will be especially pertinent after the introduction of pneumococcal conjugate vaccines with expanded serotypes. Such markers would minimize inappropriate diagnosis of false positive cases and treatment with antibacterial agents, while increasing positive predictive values for diagnosis of bacterial pneumonia. The extension of serotype coverage with the new conjugate vaccines is promising for pneumococcal infections and coverage against antibiotic-resistant strains.

The future of pneumococcal disease prevention

Pneumococcal disease (PD) is the leading cause of vaccine preventable deaths in children <5 years of age worldwide, with most of the deaths occurring in the developing world. Prevention of PD in children has been achieved by vaccination with pneumococcal conjugate vaccine (PCV), the basis for which is induction of a protective antibody response against the bacterial polysaccharide capsule. Conjugation of the polysaccharide capsule to a protein carrier enables the generation of an immunologic response to the vaccine in young children, leading to protection against infection. The heptavalent PCV, which contains 7 of the 93 known pneumococcal serotypes (4, 6B, 9V, 14, 18C, 19F, 23F) was the first PCV available, licensed in the US in 2000 and subsequently in many countries worldwide, including Latin American and Caribbean countries. Since its introduction, PCV7 has been documented effective for reducing invasive PD mortality and burden, as well as that of pneumonia and otitis media. Additionally, PD caused by the vaccine serotypes has decreased in the unimmunized population due to herd immunity induced by PCV7. Despite this success, significant disease burden still exists globally due to serotypes not included in PCV7. Currently there are 2 new PCVs that have been approved for use in children, a 10-valent vaccine (includes PCV7 serotypes plus serotypes 1, 5 and 7F) and a 13-valent vaccine (includes PCV7 serotypes plus serotypes 1, 3, 5, 6A, 7F and 19A). The selection of new serotypes to be included was based on importance of these serotypes as causes of PD. An additional 15-valent vaccine (includes PCV 7 serotypes plus serotypes 1, 3, 5, 6A, 7F, 19A, 22F and 33F) is undergoing clinical trial testing. In view of the 93 serotypes that are currently known, it seems clear that vaccines with greater coverage, likely based on proteins common to all serotypes, will be needed in the future. Technical and regulatory challenges to the development and approval of newer PCVs include a need for licensing criteria of common protein vaccines, establishment of correlates of protection for disease manifestations other than invasive disease, comparative efficacy data, and clinical trial testing of concomitant immunization of higher valency PCVs with other vaccines.

Safety and immunogenicity of a 13-valent pneumococcal conjugate vaccine in healthy infants and toddlers given with routine pediatric vaccinations in Canada

BACKGROUND

The global distribution of pneumococcal disease and emergence of nonvaccine pneumococcal serotypes prompted the development of a 13-valent pneumococcal conjugate vaccine (PCV13), with broader coverage than 7-valent PCV (PCV7). This study compared compatibility of PCV13 and PCV7 with concurrently administered diphtheria, tetanus, acellular pertussis, inactivated poliovirus, Haemophilus influenzae type b vaccine, and meningococcal C conjugate vaccine (menC), and assessed the safety and immunogenicity of PCV13.

METHODS

In this double-blind, randomized trial, children received PCV7 or PCV13 at 2, 4, 6, and 12 months with routine vaccinations. One month following the infant series and toddler dose, the responses to Hib, pertussis, menC, and specific pneumococcal serotypes were measured. Safety and tolerability were assessed daily for 4 days by parents.

RESULTS

Subjects received PCV13 (n = 300) or PCV7 (n = 303); immunogenicity assessment was completed in 265 and 268 subjects, respectively. There were no statistically significant differences between the groups in responses to Hib, pertussis, or menC after primary or booster vaccinations. More than 95% of subjects in the PCV13 group produced >0.35 μg/mL antibody to each pneumococcal serotype 1 month after the third dose, except with serotypes 23F (90%), 3 (80%), and 5 (87%). After the fourth dose, 98% to 100% of subjects achieved serotype-specific antibody concentrations >0.35 μg/mL, except for serotype 3 (85%). Safety and tolerability did not differ between groups with respect to local or systemic side effects.

CONCLUSIONS

Responses to routine childhood vaccines did not differ with PCV7 or PCV13 coadministration. Serotype-specific pneumococcal antibody concentrations were protective. The safety profile of PCV13 was favorable.