Invasive pneumococcal infections in Canadian children, 1991-1998: implications for new vaccination strategies. Canadian Paediatric Society/Laboratory Centre for Disease Control Immunization Monitoring Program, Active (IMPACT)

Streptococcus Pneumoniae-Associated Hemolytic Uremic Syndrome in the Era of Pneumococcal Vaccine

Streptococcus pneumoniae-associated hemolytic uremic syndrome (Sp-HUS) is a serious complication of invasive pneumococcal disease that is associated with increased mortality in the acute phase and morbidity in the long term. Recently, Sp-HUS definition has undergone revision and cases are categorized as definite, probable, and possible, based on less invasive serological investigations that evaluate Thomsen-Friedenreich crypt antigen (T-antigen) activation. In comparison to the pre-vaccine era, Sp-HUS incidence seems to be decreasing after the introduction of 7-serotype valence and 13-serotype valence pneumococcal vaccines in 2000 and 2010, respectively. However, Sp-HUS cases continue to occur secondary to vaccine failure and emergence of non-vaccine/replacement serotypes. No single hypothesis elucidates the molecular basis for Sp-HUS occurrence, although pneumococcal neuraminidase production and formation of T-antigen antibody complexes on susceptible endothelial and red blood cells continues to remain the most acceptable explanation. Management of Sp-HUS patients remains supportive in nature and better outcomes are being reported secondary to earlier recognition, better diagnostic tools and improved medical care. Recently, the addition of eculizumab therapy in the management of Sp-HUS for control of dysregulated complement activity has demonstrated good outcomes, although randomized clinical trials are awaited. A sustained pneumococcal vaccination program and vigilance for replacement serotypes will be the key for persistent reduction in Sp-HUS cases worldwide.

Clinical and Economic Impact of a Potential Switch from 13-Valent to 10-Valent Pneumococcal Conjugate Infant Vaccination in Canada

INTRODUCTION

Pneumococcal conjugate vaccines (PCVs) have been available in Canada since 2001, with 13-valent PCV (PCV13) added to the infant routine immunization program throughout all Canadian provinces by 2011. The use of PCVs has dramatically reduced the burden of pneumococcal disease in Canada. As a result, decision-makers may consider switching from a more costly, higher-valent vaccine to a lower-cost, lower-valent vaccine in an attempt to allocate funds for other vaccine programs. We assessed the health and economic impact of switching the infant vaccination program from PCV13 to 10-valent PCV (PCV10) in the context of the Canadian health care system.

METHODS

We performed a review of Canadian databases supplemented with published and unpublished data to obtain the historical incidence of pneumococcal disease and direct and indirect medical costs. Observed invasive pneumococcal disease (IPD) trends from surveillance data were used as a basis to forecast the future number of cases of IPD, pneumococcal pneumonia, and acute otitis media given a PCV13- or PCV10-based program. Costs and outcomes over 10 years were then estimated and presented in 2017 Canadian dollars discounted at 3% per year.

RESULTS

Switching from PCV13 to PCV10 would result in an additional 762,531 cases of pneumococcal disease over 10 years. Although PCV13 has a higher acquisition cost, switching to PCV10 would increase overall costs by over $500 million. Forecasted overall disease incidence was estimated substantially higher with PCV10 than with PCV13 primarily because of the potential reemergence of serotypes 3 and 19A. PCV13 was also cost saving compared with PCV10, even within a 5-year time horizon. Probabilistic sensitivity analysis showed that a PCV13-based program remained cost saving in all simulations.

CONCLUSION

Although switching to a PCV10-based infant vaccination program in Canada might result in lower acquisition costs, it would also result in higher public health cost and burden because of serotype reemergence.

FUNDING

Pfizer Inc.

Serotyping of Brunei pneumococcal clinical strains and the investigation of their capability to adhere and invade a brain endothelium model

INTRODUCTION

Pneumococcal infections have caused morbidity and mortality globally. Streptococcus pneumoniae (pneumococci) are commensal bacteria that colonize the nasopharynx, asymptomatically. From there, pneumococci can spread in the lungs causing pneumonia and disseminate in the bloodstream causing bacteremia (sepsis) and reach the brain leading to meningitis. Endothelial cells are one of the most important components of the blood-brain barrier that separates the blood from the brain and plays the first protective role against pneumococcal entry. Thus this study aimed to investigate on the ability of non-meningitis pneumococcal clinical strains to adhere and invade a brain endothelium model.

METHODS

Two pneumococcal Brunei clinical strains were serotyped by multiplex PCR method using oligonucleotide sequences derived from Centers for Disease Control and Prevention. A validated immortalised mouse brain endothelial cell line (bEnd.3) was used as a brain endothelium model for the study of the pneumococcal breach of the blood-brain barrier using an adherence and invasion assay.

RESULTS

Both of the pneumococcal clinical strains were found to be serotype 19F, a common circulating serotype in Southeast Asia and globally and possess the ability to adhere and invade the brain endothelial cells.

CONCLUSION

In addition, this is the first report on the serotype identification of pneumococci in Brunei Darussalam and their application on a brain endothelium model. Further studies are required to understand the virulence capabilities of the clinical strains.

The multifaceted impact of pneumococcal conjugate vaccine implementation in children in France between 2001 to 2014

In 2003, France was the first European country to recommend 7-valent pneumococcal conjugate vaccine (PCV7) for a large proportion of healthy children. With complicated recommendations, the vaccine coverage during the first 4 y of implementation was low, then progressively increased to reach 90% in 2008. The aim of this review was to describe the particular impact of PCVs in a country where the vaccine coverage was initially suboptimal. After PCV7 implementation, the PCV7 serotypes nearly disappeared among pneumococci isolated from meningitis (-73%), other invasive pneumococcal disease (IPD; -90%) and pneumococcal carriage (-97%). Consequently, the rates of penicillin-resistant strains declined. However, because of important serotype replacement, the global effect on the incidence of meningitis (-31%) or other IPD (-14%) was modest and observed only in young children < 2 y old. After PCV13 transition, with immediate high vaccine coverage, the vaccine had an important impact on all pneumococcal disease: reduction of -20% for pneumococcal meningitis, -36% for non-meningitis IPD, -32% for community acquired pneumonia and -15% for S. pneumoniae carriage. These findings underline the complexity of pneumococcal epidemiology and the importance of high and fast vaccination coverage to obtain the optimal effect of PCVs.

Effectiveness of the standard and an alternative set of Streptococcus pneumoniae multi locus sequence typing primers

Background

Multi-locus sequence typing (MLST) is a portable, broadly applicable method for classifying bacterial isolates at an intra-species level. This methodology provides clinical and scientific investigators with a standardized means of monitoring evolution within bacterial populations. MLST uses the DNA sequences from a set of genes such that each unique combination of sequences defines an isolate’s sequence type. In order to reliably determine the sequence of a typing gene, matching sequence reads for both strands of the gene must be obtained. This study assesses the ability of both the standard, and an alternative set of, Streptococcus pneumoniae MLST primers to completely sequence, in both directions, the required typing alleles.

Results

The results demonstrated that for five (aroE, recP, spi, xpt, ddl) of the seven S. pneumoniae typing alleles, the standard primers were unable to obtain the complete forward and reverse sequences. This is due to the standard primers annealing too closely to the target regions, and current sequencing technology failing to sequence the bases that are too close to the primer. The alternative primer set described here, which includes a combination of primers proposed by the CDC and several designed as part of this study, addresses this limitation by annealing to highly conserved segments further from the target region. This primer set was subsequently employed to sequence type 105 S. pneumoniae isolates collected by the Canadian Immunization Monitoring Program ACTive (IMPACT) over a period of 18 years.

Conclusions

The inability of several of the standard S. pneumoniae MLST primers to fully sequence the required region was consistently observed and is the result of a shift in sequencing technology occurring after the original primers were designed. The results presented here introduce clear documentation describing this phenomenon into the literature, and provide additional guidance, through the introduction of a widely validated set of alternative primers, to research groups seeking to undertake S. pneumoniae MLST based studies.

Cost effectiveness of the new pneumococcal vaccines: a systematic review of European studies

INTRODUCTION

Diseases caused by Streptococcus pneumoniae (pneumococcus) are a major global public health problem. Despite their importance, information on the burden of the different pneumococcal diseases is limited and estimates vary widely.

OBJECTIVE AND METHODS

We critically reviewed the full economic evaluations (FEEs) on the new pneumococcal conjugate vaccines (PCVs) conducted in the European Union (EU) to assess their potential contribution to public decision making. We selected the FEEs focussed on PCV-10 and PCV-13 and published in English from January 2007 until June 2013. We screened the selected articles to assess their main methodological features using a common checklist composed of epidemiological, clinical and economic items.

RESULTS

All the ten studies selected were based on modelling and the time horizon was always long term. Two studies focused on adults, the remaining eight on infants. Only one study based herd immunity on national data, eight used foreign data or modelling and the last did not consider it. National prices and tariffs were claimed to be sources for unit costs in all studies; however, half of them assumed price parity when one vaccine was not yet marketed, and the figures varied within the countries where more than one study was conducted. Conclusions supported the economic utility of pneumococcal vaccination in all studies, raising some concern only in (i) the independent study, which found that PCV-13 was borderline cost effective, and (ii) the study sponsored by both manufacturers, which estimated an incremental ratio slightly above the national threshold for both PCV-10 and PCV-13.

CONCLUSION

The European studies we analysed are mostly based on weak sources of data. Because of the limited information on vaccine effectiveness and lack of epidemiological and economic data, the need for extensive recourse to assumptions leads to great within- and between-study variability generated by authors' choices.

Have changing pneumococcal vaccination programmes impacted disease in Ontario?

BACKGROUND

Publicly funded infant 7-valent pneumococcal conjugate vaccine (PCV7) was introduced in Ontario, Canada in 2005 and was replaced by 10- and 13-valent vaccines (PCV10, PCV13) in October 2009 and November 2010, respectively. Among adults ≥ 65 years, a 23-valent polysaccharide vaccine (PPV23) has been universally available since 1996. In January 2012, PCV13 was approved for adults ≥ 50 years. This study examines the impact of publicly funded vaccination programmes on invasive pneumococcal disease (IPD).

METHODS

Laboratory data from population-based surveillance for IPD conducted at the Toronto Invasive Bacterial Disease Network and from Public Health Ontario Laboratories between January 1, 2008 and December 31, 2010 were analyzed.

RESULTS

Between 2008 and 2010 there were 3259 cases of IPD; overall incidence was 7.4/9.3/8.3 per 100,000 in 2008/9/10, respectively. Incidence increased significantly among adults 65+ years during the period; this group had the highest incidence (21.5-25.6/100,000). The second highest incidence in 2008 and 2009 was in infants <1 year, whereas in 2010 it was in children 1-4 years. Among children <5 years, 68% and 19% of serotypes were covered by PCV13 and PCV10, respectively, between 2008 and 2010. In 2009, 6 cases with the 3 additional PCV10 serotypes were reported in infants compared with 2 in 2010. Among persons eligible for PCV7 (born≥2004), there was a 77% decrease in the rate of IPD due to PCV7 serotypes between 2008 and 2010 and a 60% decrease in PCV7 serotypes among persons not vaccine-eligible (born<2004). There was a 15% difference in serotype coverage between PCV13 and the 23-valent polysaccharide vaccine in adults≥50 years.

CONCLUSIONS

During Ontario's PCV7 programme, serotype-specific decreases in IPD were observed, suggesting vaccine programme success, including herd immunity. Our results also suggest some early impact among infants from PCV10 introduction. A substantial burden of disease was also observed among older adults.

[Nasopharyngeal carriage of children 6 to 60 months during the implementation of the 13-valent pneumococcal conjugate vaccine]

BACKGROUND

Since 2001 in France, a nasopharyngeal carriage study was set up for children six to 24 months old. Any data are available for older children (25 to 60 months). The aim of this study is to compare the nasopharyngeal carriage in children with acute otitis media (AOM) or healthy between both age groups (6/24 months versus 25/60 months). Moreover, during the study period, the 13-valent pneumococcal conjugate vaccine (PCV13) has replaced PCV7 in June 2010.

METHODS

From October 2010 to June 2011, 58 pediatricians obtained nasopharyngeal swabs from children 6-60 months with acute otitis media (AOM) or healthy controls, to analyse the carriage of pneumococcus, Haemophilus influenzae, Moraxella catarrhalis, group A streptococcus and Staphylococcus aureus.

RESULTS

Of the 1557 enrolled children, 1258 were 6 to 24 months old (315 healthy and 943 AOM) and 299 were 25 to 60 months (102 healthy and 197 AOM). More then 85% were PCV7 vaccinated and the children of 25/60 months were rarely PCV13 vaccinated (14.1%) compared to younger children (69.9%, P<0.001). For children 6/24 months, the Streptococcus pneumoniae carriage was higher in AOM group (57.3%) versus healthy (28.9%). By contrast for older children, the difference (58.4% versus 50%) was not significant. In the healthy group, older children carried more often S. pneumoniae than younger children (50% versus 28.9%, P<0.0001). This trend was also observed for H. influenzae carriage (49% versus 18.7%, P<0.0001). Multivariate analysis in the healthy group showed that siblings and day care center (or school) increased the carriage of S. pneumoniae and H. influenzae.

CONCLUSION

These data from nasopharyngeal carriage in children 6 to 60 months old showed that pneumococcus and H. influenzae carriage is high for patients under 2 years, especially in the healthy group. Moreover, these data from the transition PCV7/PCV13, will serve as baseline in France to evaluate the impact of PCV13.

Cost-effectiveness of 2 + 1 dosing of 13-valent and 10-valent pneumococcal conjugate vaccines in Canada

Background

Thirteen-valent pneumococcal conjugate vaccine (PCV13) and 10-valent pneumococcal conjugate vaccine (PCV10) are two recently approved vaccines for the active immunization against Streptococcus pneumoniae causing invasive pneumococcal disease in infants and children. PCV13 offers broader protection against Streptococcus pneumoniae; however, PCV10 offers potential protection against non-typeable Haemophilus influenza (NTHi). We examined public health and economic impacts of a PCV10 and PCV13 pediatric national immunization programs (NIPs) in Canada.

Methods

A decision-analytic model was developed to examine the costs and outcomes associated with PCV10 and PCV13 pediatric NIPs. The model followed individuals over the remainder of their lifetime. Recent disease incidence, serotype coverage, population data, percent vaccinated, costs, and utilities were obtained from the published literature. Direct and indirect effects were derived from 7-valent pneumococcal vaccine. Additional direct effect of 4% was attributed to PCV10 for moderate to severe acute otitis media to account for potential NTHi benefit. Annual number of disease cases and costs (2010 Canadian dollars) were presented.

Results

In Canada, PCV13 was estimated to prevent more cases of disease (49,340 when considering both direct and indirect effects and 7,466 when considering direct effects only) than PCV10. This translated to population gains of 258 to 13,828 more quality-adjusted life-years when vaccinating with PCV13 versus PCV10. Annual direct medical costs (including the cost of vaccination) were estimated to be reduced by $5.7 million to $132.8 million when vaccinating with PCV13. Thus, PCV13 dominated PCV10, and sensitivity analyses showed PCV13 to always be dominant or cost-effective versus PCV10.

Conclusions

Considering the epidemiology of pneumococcal disease in Canada, PCV13 is shown to be a cost-saving immunization program because it provides substantial public health and economic benefits relative to PCV10.

Prevalence of Streptococcus pneumoniae serotypes causing invasive and non-invasive disease in South East Asia: a review

BACKGROUND

Streptococcus pneumoniae is a major cause of bacterial infections resulting in significant morbidity and mortality worldwide. Currently, up to 13 serotypes are included in pneumococcal conjugate vaccines (PCVs). However, the serotype formulation of these vaccines was initially designed to protect children against serotypes most commonly causing invasive disease in North America, and may not reflect the serotype distribution across the world. Data regarding pneumococcal epidemiology from the other parts of the world, in particular South East Asia, has not been reviewed.

METHODS

This systematic literature review analyses published serotype data regarding S. pneumoniae isolates from South East Asian countries (defined as countries belonging to the Association of South East Asian Nations, ASEAN): Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand and Vietnam up to 3rd of March 2012.

RESULTS

Analysis of data from six ASEAN countries, from which information on pneumococcal serotypes was available, showed that the most common disease causing serotypes (in rank order) were 19F, 23F, 14, 6B, 1, 19A and 3. Serotype distribution of pneumococcal isolates was similar across the ASEAN region. Serotype level data was more commonly reported for pneumococcal isolates causing invasive pneumococcal disease than for those from non-invasive disease. Studies from Malaysia, Thailand and Singapore contributed the largest proportion of pneumococcal isolates, and serotype data, when compared to other ASEAN countries.

CONCLUSION

This review demonstrates that the majority of IPD causing serotypes in SE Asia are included in currently licensed PCVs. However, PCV's are included in the routine childhood immunisation schedule of only one of the ten countries included in this analysis. Our findings demonstrate the scarcity of information available on serotype prevalence and distribution of pneumococci in SE Asia.

Invasive Streptococcus pneumoniae infection causing hemolytic uremic syndrome in children: Two recent cases

INTRODUCTION

Streptococcus pneumoniae is an uncommon cause of hemolytic uremic syndrome (HUS) with a unique pathophysiology that differs from Shiga toxin-related HUS.

METHODS

Case descriptions for each patient are provided. Each strain of S pneumoniae was subjected to a pulsed-field gel electrophoresis (PFGE) analysis, Shiga toxin assay and polymerase chain reaction to detect Shiga toxin genes. A review of the current literature was conducted.

CASE PRESENTATIONS

Two patients with S pneumoniae-related HUS that presented to the Alberta Children's Hospital, Calgary, Alberta, within four weeks of each other in 2001 are described. Both presented with pneumonia and empyema with associated HUS. Both patients required dialysis, one patient for 10 days and the other for 18 days. Neither patient demonstrated evidence of Shiga toxin-related disease. S pneumoniae isolated from blood or pleural fluid was penicillin susceptible. One isolate was serotype 3 and the other was serotype 14. The two strains had different PFGE patterns. Both patients recovered well with no persistent renal dysfunction.

CONCLUSIONS

S pneumoniaecontinues to be an uncommon but important cause of HUS. Most cases can be confirmed or at least considered probable without performing a renal biopsy.

Epidemiological and economic burden of pneumococcal diseases in Canadian children

BACKGROUND

With the arrival of a new conjugate pneumococcal vaccine, it is important to estimate the burden of pneumococcal diseases in Canadian children. The epidemiological data and the economic cost of these diseases are crucial elements in evaluating the relevance of a vaccination program.

METHODS

Using provincial databases, ad hoc surveys and published data, age-specific incidence rates of pneumococcal infections were estimated in a cohort of 340,000 children between six months and nine years of age. The costs of these diseases to the health system and to families were also evaluated using data from Quebec and Manitoba.

RESULTS

Cumulative risks were one in 5000 for pneumococcal meningitis, one in 500 for bacteremia and one in 20 for pneumonia, leading to 16 deaths in the cohort. About 262,000 otitis media episodes and 32,000 cases of myringotomy with ventilation tube insertion were attributable to Streptococcus pneumoniae. Societal costs were estimated at $125 million, of which 32% was borne by the health system and 68% was borne by families. Invasive infections represented only 2% of total costs, while 84% were generated by otitis media.

CONCLUSION

Pneumococcal infections represent a significant burden for Canadian children and society that could be significantly reduced through immunization.

Reduced susceptibility to penicillin among pneumococci causing invasive infection in children - Canada, 1991 to 1998

OBJECTIVE

To determine, over time, the rate and serotypes of pneumococci with reduced penicillin susceptibility obtained from children with invasive infection.

DESIGN

Active, hospital-based, multicentre surveillance spanning from 1991 to 1998.

SETTING

Eleven Canadian tertiary care paediatric facilities located from coast to coast.

POPULATION STUDIED

1847 children with invasive pneumococcal infection whose isolates (from a normally sterile site) were available for serotyping and standardized testing for penicillin susceptibility at the National Centre for Streptococcus.

MAIN RESULTS

The prevalence of reduced penicillin susceptibility increased from 2.5% of 197 cases in 1991 to 13.0% of 276 cases in 1998. In the latter year, 8.7% of isolates had intermediate level resistance, and 4.3% had high level resistance. Since they were first detected in 1992, strains with high level resistance have been encountered only sporadically at most centres, but by 1998, all centres but two had encountered examples. Of 40 isolates with high level resistance and 101 isolates with intermediate level resistance, serotypes matched those included in new seven-valent conjugate vaccines for children in 97.5% and 79.2% of cases, respectively.

CONCLUSIONS

Pneumococci with reduced susceptibility to penicillin are increasing in frequency across Canada among children with invasive infection. The Immunization Monitoring Program, Active data indicate that new conjugate vaccines could help to curb infections due to pneumococci with reduced susceptibility to penicillin but are unlikely to control completely the problem of antibiotic resistance.

Pneumococcal conjugate vaccination in Canadian infants and children younger than five years of age: Recommendations and expected benefits

INTRODUCTION

Streptococcus pneumoniae infection may result in invasive pneumococcal disease (IPD), such as bacteremia, meningitis and bacteremic pneumonia, or in non-IPD, such as pneumonia, sinusitis and otitis media. In June 2001, a heptavalent pneumococcal conjugate vaccine (PCV7) (Prevnar, Wyeth Pharmaceuticals, Canada) was approved for use in children in Canada. The objective of the present paper is to review S pneumoniae-induced disease incidence and vaccine recommendations in Canadian infants and children younger than five years of age. Particular attention is given to the expected benefits of vaccination in Canada based on postmarketing data and economic modelling.

METHODS

Searches were performed on PubMed and Web of Science databases and specific Canadian journals using the key words 'pneumococc*', 'vaccine', 'conjugate', 'infant' and 'Canadian'.

RESULTS AND DISCUSSION

PCV7 appears to be safe and effective against IPD and non-IPD in children younger than five years of age and, more importantly, in children younger than two years of age (who are at highest risk for IPD). An examination of postmarketing data showed a reduction in incidence of pneumococcal disease in age groups that were vaccinated and in older age groups, indicating the likelihood of herd protection. Concurrently, there was a reduction in the occurrence of antimicrobial-resistant isolates.

CONCLUSIONS

The results from the present review suggest that PCV7 is currently benefiting Canadian children and society by lowering S pneumoniae-associated disease. Additional gains from herd protection and further reductions in antimicrobial resistance will be achieved as more Canadian children younger than five years of age are routinely vaccinated with PCV7.

Seven-valent pneumococcal conjugate vaccine in pediatric solid organ transplant recipients: a prospective study of safety and immunogenicity

OBJECTIVES

To determine the safety and immunogenicity of the conjugate pneumococcal vaccine (PCV7) in pediatric solid organ transplant recipients.

PATIENTS AND METHODS

Pediatric solid organ transplant recipients were prospectively enrolled at > or =4 months following transplantation. Eligible pneumococcal vaccine-naive subjects received 3 doses of PCV7 at 8 week intervals, followed 8 weeks later by a dose of the 23-valent vaccine (PV23). Serology was done at baseline, 8 weeks following doses 2 and 3 of PCV7 and 8-12 weeks after PV23. Repeated measures analyses were done using SAS 9.

RESULTS

Eighty-one recipients commenced immunization at a median age of 7.8 (0.6-17.5) years and a median time from transplantation to immunization of 1.3 (0.3-6.0) years. There were 31 heart, 18 liver, 5 lung, and 27 kidney recipients. Reported adverse events following vaccine doses included local reactions (PCV7: PV23 = 19%:16%) and fever (PCV7: PV23 = 3.8%:4.9%) and there were no serious reactions. Two doses of PCV7 induced > or =2 fold increases in geometric mean concentrations (GMCs) in all organ groups. Cardiac and lung recipients demonstrated additional benefit from a third dose of PCV7. The cardiac recipients showed most benefit from boosting with PV23 with significant increases in GMC's (P < or = 0.008). The time of initiation of the vaccine strategy posttransplantation predicted seroprotection.

CONCLUSION

PCV7 was safe and immunogenic in solid organ recipients. Three doses of this vaccine appear beneficial for selected organ groups. PV23 when administered at >/=1 year posttransplantation was useful in boosting antibody responses in patient groups demonstrating lower rates of responsiveness.

The incidence of pediatric invasive pneumococcal disease in Chiba prefecture, Japan (2003-2005)

OBJECTIVES

The purpose of the study is to evaluate the incidence, spectrum of clinical manifestations and outcome of invasive pneumococcal disease (IPD) in children in Chiba prefecture, Japan.

METHODS

To determine the precise incidence of IPD in Chiba prefecture, we implemented a retrospective survey of the period from 2003 to 2005. A written questionnaire was sent to 45 hospitals that have pediatric wards, and information was obtained from all hospitals. The questionnaire included the clinical diagnosis, patient's age, underlying disease, prognosis and antimicrobial susceptibility of the isolated strains.

RESULTS

During the 3 study years, 130 patients were diagnosed with IPD. The mean annual incidence rates of IPD among children <2 and <5 years were 19.5-23.8 and 12.6-13.8 per 100,000, respectively. Among 130 patients with systemic infection, 66 patients had bacteremia, 39 had pneumonia and 16 had meningitis. Five patients had neurological sequelae and 2 patients died. Seventy-four out of 115 isolates (64.3%) exhibited resistance to penicillin G.

CONCLUSIONS

The annual incidence of pediatric IPD has remained constant during the study period. Two-third of isolated strains were at least partially resistant to penicillin G. Establishment of appropriate antibiotic therapy against IPD due to penicillin-resistant strains and the introduction of pneumococcal conjugate vaccines are emergent issues in Japan.

Empyema associated with community-acquired pneumonia: a Pediatric Investigator's Collaborative Network on Infections in Canada (PICNIC) study

BACKGROUND

Although the incidence of serious morbidity with childhood pneumonia has decreased over time, empyema as a complication of community-acquired pneumonia continues to be an important clinical problem. We reviewed the epidemiology and clinical management of empyema at 8 pediatric hospitals in a period before the widespread implementation of universal infant heptavalent pneumococcal vaccine programs in Canada.

METHODS

Health records for children<18 years admitted from 1/1/00-31/12/03 were searched for ICD-9 code 510 or ICD-10 code J869 (Empyema). Empyema was defined as at least one of: thoracentesis with microbial growth from pleural fluid, or no pleural fluid growth but compatible chemistry or cell count, or radiologist diagnosis, or diagnosis at surgery. Patients with empyemas secondary to chest trauma, thoracic surgery or esophageal rupture were excluded. Data was retrieved using a standard form with a data dictionary.

RESULTS

251 children met inclusion criteria; 51.4% were male. Most children were previously healthy and those<or=5 years of age comprised 57% of the cases. The median length of hospitalization was 9 days. Admissions occurred in all months but peaked in winter. Oxygen supplementation was required in 77% of children, 75% had chest tube placement and 33% were admitted to an intensive care unit. While similarity in use of pain medication, antipyretics and antimicrobial use was observed, a wide variation in number of chest radiographs and invasive procedures (thoracentesis, placement of chest tubes) was observed between centers. The most common organism found in normally sterile samples (blood, pleural fluid, lung biopsy) was Streptococcus pneumoniae.

CONCLUSION

Empyema occurs most commonly in children under five years and is associated with considerable morbidity. Variation in management by center was observed. Enhanced surveillance using molecular methods could improve diagnosis and public health planning, particularly with regard to the relationship between immunization programs and the epidemiology of empyema associated with community-acquired pneumonia in children.

Pneumococcal pneumonia in hospitalized Uruguayan children and potential prevention with different vaccine formulations

OBJECTIVES

To provide information on pneumococcal pneumonias, on their associated serotypes, and to estimate the coverage potentially afforded by antipneumococcal vaccines.

STUDY DESIGN

A retrospective study (2000 to 2004) was performed of patients with pneumococcal pneumonia aged 0 to 14 years admitted to the National Reference Children's Hospital in Uruguay. Selected clinical data, radiographic interpretation, and microbiologic reports were obtained for analysis.

RESULTS

Of 410 enrolled patients, 384 had consolidated pneumonia/pleural effusion and 26 had infiltrates without consolidation: Pneumococcus was identified in blood or in pleural fluid of 387 patients; 21 serotypes were identified. The most frequent serotypes in decreasing order were serotypes 14, 1, 5, 3, 9V, 6B, and 7F. Forty-eight percent of invasive Streptococcus pneumoniae isolates were obtained from children younger than 24 months. For this group, the 7-valent vaccine would cover 60%, but a 10-valent vaccine would cover 83.8%.

CONCLUSIONS

This study provides information on pneumonia of proven S. pneumoniae causes and their associated serotypes, enabling estimation of potential effect of pneumococcal conjugate vaccines.

International Circumpolar Surveillance System for invasive pneumococcal disease, 1999-2005

The International Circumpolar Surveillance System is a population-based surveillance network for invasive bacterial disease in the Arctic. The 7-valent pneumococcal conjugate vaccine (PCV7) was introduced for routine infant vaccination in Alaska (2001), northern Canada (2002-2006), and Norway (2006). Data for invasive pneumococcal disease (IPD) were analyzed to identify clinical findings, disease rates, serotype distribution, and antimicrobial drug susceptibility; 11,244 IPD cases were reported. Pneumonia and bacteremia were common clinical findings. Rates of IPD among indigenous persons in Alaska and northern Canada were 43 and 38 cases per 100,000 population, respectively. Rates in children <2 years of age ranged from 21 to 153 cases per 100,000 population. In Alaska and northern Canada, IPD rates in children <2 years of age caused by PCV7 serotypes decreased by >80% after routine vaccination. IPD rates are high among indigenous persons and children in Arctic countries. After vaccine introduction, IPD caused by non-PCV7 serotypes increased in Alaska.

Effectiveness of pneumococcal conjugate vaccine in Greater Vancouver, Canada: 2004-2005

Active, population-based surveillance for invasive pneumococcal infections in Greater Vancouver (population 473,000 children) demonstrated a rapid, substantial decrease in incidence rates for children 6-23 months old with routine infant vaccination. In the subpopulation with best case ascertainment disease rates for 6-23 month olds decreased 84.6% (92.5% for vaccine serotypes).

Invasive pneumococcal infections in Canadian children, 1998-2003: implications for new vaccination programs

BACKGROUND

We conducted active surveillance for invasive pneumococcal disease to assess the serotype and antibiotic resistance patterns in Canada prior to universal infant immunization programs, in most provinces.

METHODS

Active surveillance was conducted by the 12 centres of the Canadian Paediatric Society's Immunization Monitoring Program, Active (IMPACT). This report includes children 16 years of age and younger with S. pneumoniae isolated from a normally sterile site, in 1998-2003.

RESULTS

During six years of surveillance, 1,868 eligible cases were reported. The 7-valent pneumococcal conjugate vaccine (PCV7) matched 79% of isolates, including 84% from 6-23 month olds and 80% from 2-5 year olds. The proportion of isolates matched by PCV7 significantly decreased over the surveillance period from 81% in 1998 to 73% in 2003 (p = 0.005). The 23-valent polysaccharide vaccine (PPS) matched 90% of isolates from children 2 years or older. Penicillin non-susceptibility rate was stable at 16% of isolates. Cefotaxime/ceftriaxone resistance rate was 5% and limited to penicillin-resistant isolates. Serotypes found in PCV7 accounted for 89% of penicillin-resistant isolates (100% including cross-reacting types 6A and 19A).

CONCLUSION

PCV7 matched three quarters of the isolates from young children as immunization programs began; therefore some program failures are inevitable. Children > or =5 years with predisposing conditions need the broader protection of 23-valent PPS vaccine and special attention from providers to ensure receipt. The rate of penicillin resistance remained steady over the last six years. The majority of isolates non-susceptible to penicillin are found in PCV7.

The roles of pneumococcal serotypes 1 and 5 in paediatric invasive disease

A small number of serotypes are responsible for most invasive pneumococcal disease in children worldwide. Serotypes 1 and 5 were among the first pneumococcal serotypes to be identified, reflecting their great prominence as causes of disease in the early part of the 20th century. In the antibiotic era, these serotypes persist as important causes of disease in children in most countries even though they, unlike some other common serotypes, remain sensitive to antimicrobial agents. These types also exhibit a high level of virulence, cause disease clusters or outbreaks, infect all age groups, and cause severe disease. Future vaccine formulations that protect against these types are important for developed and developing countries alike.

The burden of pneumococcal disease in the Canadian population before routine use of the seven-valent pneumococcal conjugate vaccine

BACKGROUND

In the United States, implementation of the seven-valent conjugate vaccine into childhood immunization schedules has had an effect on the burden of pneumococcal disease in all ages of the population. To evaluate the impact in Canada, it is essential to have an estimate of the burden of pneumococcal disease before routine use of the vaccine.

METHODS

The incidence and costs of pneumococcal disease in the Canadian population in 2001 were estimated from various sources, including published studies, provincial databases and expert opinion.

RESULTS

In 2001, there were 565,000 cases of pneumococcal disease in the Canadian population, with invasive infections representing 0.7%, pneumonia 7.5% and acute otitis media 91.8% of cases. There were a total of 3000 deaths, mainly as a result of pneumonia and largely attributable to the population aged 65 years or older. There were 54,330 life-years lost due to pneumococcal disease, and 37,430 quality-adjusted life-years lost due to acute disease, long-term sequelae and deaths. Societal costs were estimated to be $193 million (range $155 to $295 million), with 82% borne by the health system and 18% borne by families. Invasive pneumococcal infections represented 17% of the costs and noninvasive infections represented 83%, with approximately one-half of this proportion attributable to acute otitis media and myringotomy.

CONCLUSIONS

The burden of pneumococcal disease before routine use of the pneumococcal conjugate vaccine was substantial in all age groups of the Canadian population. This estimate provides a baseline for further analysis of the direct and indirect impacts of the vaccine.

Prevalence of Toll-like receptor signalling defects in apparently healthy children who developed invasive pneumococcal infection

Human primary immunodeficiencies affecting Toll-like receptor (TLR) signalling reveal a non-redundant role for TLR function in defense against pneumococcal infection. To determine the clinical relevance of TLR abnormalities, we studied a population predicted to be enriched for TLR defects-healthy children who had developed invasive pneumococcal infection in the absence of classic risk factors for infection. We describe the development and optimization of a peripheral blood TLR assay. By testing 38 healthy control neonates, children and adults we demonstrated that TLR function was stable over the first six decades of life. We tested 50 children with a history of invasive pneumococcal infection and although TLR defects were predicted to be over-represented in this population, we did not identify any TLR abnormalities. Although TLR signalling defects are associated with greatly enhanced susceptibility to invasive pneumococcal infection, our results suggest that routine clinical screening for TLR defects in healthy children who develop invasive pneumococcal infection is not justified.

Safety and immunogenicity of heptavalent pneumococcal conjugate vaccine booster in taiwanese toddlers

BACKGROUND/PURPOSE

Pneumococcal infection causes high morbidity and mortality in children. Prevention of pneumococcal diseases by effective vaccination is an urgent need. This study evaluated the safety and immunogenicity of heptavalent pneumococcal conjugate (7VPnC) vaccine (serotypes 4, 6B, 9V, 14, 18C, 19F, 23F) booster dose administered at 15-20 months of age in Taiwanese toddlers.

METHODS

Fifty-eight healthy Taiwanese toddlers who were primed with three doses of the 7VPnC vaccine in infancy received a booster dose in an open-label, noncomparative trial. Routine oral polio vaccine and diphtheria toxoid, tetanus toxoid, and pertussis vaccine were administered concomitantly. Surveillance for safety was conducted after vaccination. Antibody concentration to each of the seven pneumococcal serotypes was measured before and 1 month after the booster dose.

RESULTS

Mild to moderate local reactions were common (45-50%). Fever, fussiness, restlessness, and loss of appetite were the most frequent systemic reactions (31-50%). Before the booster dose of vaccine, 68% (for serotype 18C) to 100% (for serotype 14) of subjects had antibody concentrations >or= 0.2 microg/mL to different pneumococcal serotypes. After the booster dose, the geometric mean concentration of IgG increased significantly (p < 0.001) for all seven serotypes indicating the induction of immunologic memories. Ninety-eight percent of the toddlers had antibody concentration >or= 0.2 microg/mL against all serotypes after the booster.

CONCLUSION

The 7VPnC vaccine containing the prevalent serotypes in Taiwan is safe and effective in boosting immunity against pneumococcal disease in Taiwanese children.

Childhood meningitis in Kuwait: epidemiology of etiologic agents and the need for pneumococcal disease prevention

OBJECTIVE

To investigate the epidemiology of the etiologic agents causing bacterial meningitis in Kuwait.

SUBJECTS AND METHODS

This is a retrospective analysis of the medical records of children 1 month to 12 years old who had cerebrospinal fluid (CSF) findings consistent with meningitis. Patients were identified from the records of the Departments of Microbiology and Communicable Diseases in six regional hospitals during 2001. They were divided into bacterial and viral infective groups.

RESULTS

Ninety children had CSF findings consistent with meningitis, 44 bacterial (23 culture proven, 21 probable) and 46 viral. Streptococcus pneumoniae and Neisseria meningitidis were the most frequently isolated organisms (44 and 30%, respectively). A 2-month-old child had Haemophilus influenzae and was the only mortality of this series. S. pneumoniae is the leading bacterial agent causing meningitis in children under the age of 1 year; 61% had bacterial meningitis compared to 37% with viral meningitis. Sequelae were encountered in 23% of bacterial cases.

CONCLUSION

The results indicate that S. pneumoniae is the leading bacterial agent causing meningitis, indicating a need for the introduction of polyvalent pneumococcal vaccine.

An analytical framework for immunization programs in Canada

Recent years have seen an increase in the number of new vaccines available on the Canadian market, and increasing divergence in provincial and territorial immunization programs as jurisdictions must choose among available health interventions with limited funding. We present an analytical framework, which we have developed to assist in the analysis and comparison of potential immunization programs. The framework includes 58 criteria classified into 13 categories, including the burden of disease, vaccine characteristics and immunization strategy, cost-effectiveness, acceptability, feasibility, and evaluability of program, research questions, equity, ethical, legal and political considerations. To date this framework has been utilized in a variety of different contexts, such as to structure expert presentations and reports and to examine the degree of consensus and divergence among experts, and to establish priorities. It can be transformed for a variety of other uses such as educating health professionals and the general public about immunization.

Interventions to improve antibiotic prescribing practices in ambulatory care

BACKGROUND

The development of resistance to antibiotics by many important human pathogens has been linked to exposure to antibiotics over time. The misuse of antibiotics for viral infections (for which they are of no value) and the excessive use of broad spectrum antibiotics in place of narrower spectrum antibiotics have been well-documented throughout the world. Many studies have helped to elucidate the reasons physicians use antibiotics inappropriately.

OBJECTIVES

To systematically review the literature to estimate the effectiveness of professional interventions, alone or in combination, in improving the selection, dose and treatment duration of antibiotics prescribed by healthcare providers in the outpatient setting; and to evaluate the impact of these interventions on reducing the incidence of antimicrobial resistant pathogens.

SEARCH STRATEGY

We searched the Cochrane Effective Practice and Organisation of Care Group (EPOC) specialized register for studies relating to antibiotic prescribing and ambulatory care. Additional studies were obtained from the bibliographies of retrieved articles, the Scientific Citation Index and personal files.

SELECTION CRITERIA

We included all randomised and quasi-randomised controlled trials (RCT and QRCT), controlled before and after studies (CBA) and interrupted time series (ITS) studies of healthcare consumers or healthcare professionals who provide primary care in the outpatient setting. Interventions included any professional intervention, as defined by EPOC, or a patient-based intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed study quality.

MAIN RESULTS

Thirty-nine studies examined the effect of printed educational materials for physicians, audit and feedback, educational meetings, educational outreach visits, financial and healthcare system changes, physician reminders, patient-based interventions and multi-faceted interventions. These interventions addressed the overuse of antibiotics for viral infections, the choice of antibiotic for bacterial infections such as streptococcal pharyngitis and urinary tract infection, and the duration of use of antibiotics for conditions such as acute otitis media. Use of printed educational materials or audit and feedback alone resulted in no or only small changes in prescribing. The exception was a study documenting a sustained reduction in macrolide use in Finland following the publication of a warning against their use for group A streptococcal infections. Interactive educational meetings appeared to be more effective than didactic lectures. Educational outreach visits and physician reminders produced mixed results. Patient-based interventions, particularly the use of delayed prescriptions for infections for which antibiotics were not immediately indicated effectively reduced antibiotic use by patients and did not result in excess morbidity. Multi-faceted interventions combining physician, patient and public education in a variety of venues and formats were the most successful in reducing antibiotic prescribing for inappropriate indications. Only one of four studies demonstrated a sustained reduction in the incidence of antibiotic-resistant bacteria associated with the intervention.

AUTHORS' CONCLUSIONS

The effectiveness of an intervention on antibiotic prescribing depends to a large degree on the particular prescribing behaviour and the barriers to change in the particular community. No single intervention can be recommended for all behaviours in any setting. Multi-faceted interventions where educational interventions occur on many levels may be successfully applied to communities after addressing local barriers to change. These were the only interventions with effect sizes of sufficient magnitude to potentially reduce the incidence of antibiotic-resistant bacteria. Future research should focus on which elements of these interventions are the most effective. In addition, patient-based interventions and physician reminders show promise and innovative methods such as these deserve further study.

High mortality of invasive pneumococcal disease compared with meningococcal disease in critically ill children

OBJECTIVE

To ascertain outcome, patterns of disease, incidence of concurrent infection, superinfection and penicillin resistance in children requiring intensive care for Streptococcus pneumoniae infection and compare it to a similar disease pattern, namely Neisseria meningitidis b infection.

DESIGN AND SETTING

Prospective cohort study in a regional paediatric intensive care unit (PICU).

PATIENTS AND PARTICIPANTS

Children with invasive pneumococcal and meningococcal disease requiring intensive care.

MEASUREMENTS AND RESULTS

The study included 22 children with invasive pneumococcal disease (IPD), median age 14 months (interquartile range 3-52), median Paediatric Index of Mortality (PIM) 0.051 (0.028-0.066), median length of PICU stay 8.5 days (4-13). Four patients died, three (13.5%) attributable to IPD. Incidence of concurrent infection 27%. There were no superinfections. All S. pneumoniae were sensitive to cefotaxime; one isolate (3.7%) was resistant to penicillin. There were 186 children with meningococcal disease (MD), with a higher PIM (median 0.068, 0.033-0.108), older age (29 months, 10.7-77.9) and shorter length of PICU stay (median 3 days, 2-6). Eight (4.3%) children died from MD. Incidence of concurrent and superinfection was 18% and 6%, respectively in children with MD. All N. meningitidis cases were sensitive to cefotaxime and penicillin. The standardized mortality ratio was considerably higher with IPD (2.0) than with MD (0.52).

CONCLUSIONS

In invasive pneumococcal disease preventative measures including early recognition, immediate antibiotic therapy and vaccination need to be taken in the community, similar to the control of meningococcal disease. Invasive pneumococcal disease should command the same respect as meningococcal disease.

Development of natural antibodies to pneumococcal surface protein A, pneumococcal surface adhesin A and pneumolysin in Filipino pregnant women and their infants in relation to pneumococcal carriage

For vaccine development it is important to know how antibodies develop after natural pneumococcal contacts. This work was done to receive information about the development of natural antibodies to pneumococcal surface protein A (PspA), pneumococcal surface adhesin A (PsaA) and pneumolysin (Ply), in early infancy and to receive information on how nasopharyngeal carriage of Streptococcus pneumoniae in infants affects the antibody concentrations. The antibody concentrations to PspA, PsaA and Ply were measured by EIA in serum samples of 51 pregnant women, in six consecutive serum samples of 173 infants (samples from 7 to 48 weeks of age), as well as in 39 cord bloods. Nasopharyngeal swabs were also collected from the infants and cultured for pneumococci. The geometric mean concentration (GMC) of anti-PspA and -Ply decreased until 18 weeks of age and started to increase thereafter, but was still at 48 weeks lower than in the mothers. The GMC of anti-PsaA in the infants increased significantly by age and reached the GMC of the mothers already at 14 weeks of age. The increase in antibody concentration in the infants was associated with pneumococcal carriage, but followed the different kinetics depending on the antigen. High maternal anti-Ply antibodies were negatively associated with the risk of pneumococcal carriage (OR 0.78, 0.61-0.99). This indicates that high maternal anti-Ply could be associated with lower pneumococcal carriage acquisition in infants.

Invasive pneumococcal disease in pediatric organ transplant recipients: a high-risk population

There are few studies on invasive pneumococcal disease in pediatric transplant recipients. Given this fact plus the advent of pneumococcal conjugate vaccines, we conducted a retrospective study at a major pediatric transplant center. The objectives were to determine the incidence and outcomes of invasive pneumococcal diseases in the patient population and to examine the timing of these infections after transplantation. We determined that invasive disease occurred at a rate that was significantly greater than the rate extrapolated from generally healthy children <5 yr of age (176 episodes per 100 000 children per year vs. 35-68.3 per 100 000 children per year). In addition, disease occurred at a median of approximately 20 months after transplantation, thereby theoretically allowing enough time for vaccination with the 7-valent conjugate vaccine. The study also documented significant missed vaccination opportunities.

Comparison of incidence of invasive Streptococcus pneumoniae disease among children before and after introduction of conjugated pneumococcal vaccine

OBJECTIVES

The objective was to determine whether there has been a significant decrease in the incidence of invasive Streptococcus pneumoniae disease in the Louisville, KY, area since heptavalent pneumococcal conjugate vaccine was introduced in the winter of 1999-2000. A secondary objective was to collect demographic data regarding invasive S. pneumoniae disease in the Louisville, KY, area during the 1997-2002 period.

METHODS

Data on cases of invasive S. pneumoniae disease (defined by a positive culture for S. pneumoniae from the blood, pleural fluid or cerebrospinal fluid) were collected from the microbiology laboratories and medical records departments of all hospitals that treat children in the Louisville area, for 1997-2002. Trends in case rates for all cases of invasive S. pneumoniae disease from 1999 to 2002 were observed, and demographic and other factors regarding this illness were recorded for each patient.

RESULTS

The trend for rates of invasive pneumococcal disease showed a significant decrease during the study period for all ages combined (P < 0.001), for children younger than 2 years of age (P = 0.002) and for children 2 to 5 years of age (P = 0.002). The mean age for children was 2.22 years, with a male/female ratio of 1.8:1. The most common final diagnoses for the patients were bacteremia without focus, pneumonia and meningitis. Forty-eight percent of the organisms were resistant to penicillin. There was a significantly higher rate of resistance to penicillin among S. pneumoniae strains that caused cerebrospinal fluid infection than among strains that caused non-cerebrospinal fluid infection (P < 0.001). The case fatality rate was 2.6%.

CONCLUSION

Case rates for invasive S. pneumoniae disease among children decreased significantly in the 2-year period after introduction of the heptavalent S. pneumonia protein conjugate vaccine into this community.

A survey of attitudes towards paediatric vaccinations amongst Canadian naturopathic students

Previous studies have suggested that providers of alternative medicine may harbour anti-vaccination attitudes and that these attitudes may develop at an early stage in their careers. We further explored this question by conducting a survey to determine the attitudes of students of naturopathic medicine, a growing alternative medicine discipline, towards recommended paediatric vaccines. We sampled all 4 years of students at the Canadian College of Naturopathic Medicine (CCNM) and obtained a response rate of 59.4% (312 of 525). We found that only 12.8% (40 of 312) of the respondents would advise full vaccination; however, 74.4% (232 of 312) of the respondents would advise partial vaccination. Importantly, both willingness to advise full vaccination and trust in public health and conventional medicine decreased in students in the later years of the programme. Our findings suggest that public health and conventional medical supporters of vaccination need to identify mechanisms for engaging in discussion with this population of complementary/alternative medical professionals at an early stage in their careers.

Invasive pneumococcal disease in Costa Rican children: a seven year survey

BACKGROUND

Streptococcus pneumoniae is a leading cause of invasive bacterial disease in children worldwide. Although morbidity and mortality associated with invasive pneumococcal disease (IPD) are known to be high in Latin American infants, the current situation for Central American children is unclear.

METHODS

A 7-year retrospective review of IPD cases (January 1995 to December 2001) treated at the National Children's Hospital in San José, Costa Rica.

RESULTS

We analyzed 135 episodes that occurred in 132 patients. The mean age of presentation was 35.7 months (range, 0 to 11.4 ys), with 73.3% of all episodes occurring in patients <5 years of age and 56% occurring in patients <24 months of age. Underlying medical conditions were present in 47% of children. The most common clinical presentations were meningitis in 56 (41.5%) patients, pneumonia in 36 (26.7%), bacteremia alone in 30 (22.2%), peritonitis in 10 (7.4%), septic arthritis in 2 (1.5%) and osteomyelitis in 1 (0.7%). The case fatality rate was 14.4%, and children <2 years of age had the highest rates of complications, sequelae and death. Penicillin or cefotaxime nonsusceptibility was observed in 14.3% (10.7% intermediate, 3.6% resistant) and 4.5% (1.5% intermediate, 3% resistant) of tested isolates, respectively.

CONCLUSIONS

IPD in Costa Rica is associated with high morbidity and mortality, particularly among young infants. Most prevalent IPD are the ones observed in developed countries before the introduction of current conjugated vaccine. Penicillin and third generation cephalosporin resistance in invasive cases is present at low rates.

Benefits and costs of immunization of children with pneumococcal conjugate vaccine in Canada

To estimate cost-effectiveness of routine and catch-up vaccination of Canadian children with seven-valent pneumococcal conjugate vaccine, a simulation model was constructed. In base scenario (vaccination coverage: 80%, and vaccine price: 58 dollars per dose), pneumococcal disease incidence reduction would be superior to 60% for invasive infections, and to 30% for non-invasive infections, but the number of deaths prevented would be small. Annual costs of routine immunization would be 71 million dollars (98% borne by the health system). Societal benefit to cost ratio would be 0.57. Net societal costs per averted pneumococcal disease would be 389 dollars and 125,000 per life-year gained (LYG). Vaccine purchase cost is the most important variable in sensitivity analyses, and program costs would be superior to societal benefits in all likely scenarios. Vaccination would result in net savings for society, if vaccine cost is less than 30 dollars per dose. Economic indicators of catch-up programs are less favorable than for routine infant immunization.

Pediatric invasive pneumococcal disease in a teaching hospital in Bangkok

BACKGROUND

Increased problems with drug-resistant Streptococcus pneumoniae (SP) and the dearth of epidemiologic and clinical information on invasive pneumococcal disease in children in Asia formed the basis for this study.

METHODS

A periodic retrospective review of the records of 0-15-year-old patients was conducted at a teaching hospital in Bangkok, during 1971-2000.

RESULTS

Infections with penicillin-non-susceptible SP (PNSSP) strains rapidly increased after they first appeared in 1988, and they accounted for 71% (29/41) of the total cases during 1996-2000. Of 137 patients, 74% were <60 months old, and 66% had an underlying condition. Infections included: bacteremia without focus 51; pneumonia 38; meningitis 35; peritonitis 13; and bone/joint infection 2. Two patients had two foci of infection. Eight of 10 episodes in patients with AIDS were bacteremic pneumonia. Median ages (range) in months for patients with and without an underlying condition were 24 (1-174) and 10 (0-160); and for the patients without an underlying condition they were: pneumonia 23 (4-156); bacteremia without focus 12 (0-160); and meningitis 7 (2-156). Case-fatality rates were 18% and 2% for patients with and without an underlying condition. The study also examined factors associated with PNSSP infection and death. During 1991-2000, 74% (43/58) of the total cases occurred from November to April, which are dry months.

CONCLUSIONS

This study population contained a high proportion with both an underlying condition and infection with PNSSP, and a moderately low proportion with bacteremia without focus. The disease was two to three times more common in dry months than in rainy months.

Epidemiology, antibiotic susceptibility, and serotype distribution of Streptococcus pneumoniae associated with invasive pneumococcal disease in British Columbia - A call to strengthen public health pneumococcal immunization programs

BACKGROUND

This study examined the epidemiology, antibiotic susceptibility and serotype distribution of Streptococcus pneumoniae associated with invasive pneumococcal disease (IPD) in British Columbia.

METHODS

Six hospitals and one private laboratory network participated in a prospective, sentinel laboratory based surveillance study of IPD, between October 1999 and October 2000. At each site, S pneumoniae isolates were collected and epidemiological data were gathered using a structured questionnaire, for all cases of IPD meeting the study case definition. Isolates were serotyped and tested for antimicrobial susceptibility. Bivariate associations were analyzed and multivariate logistic regression was used to identify independent risk factors associated with hospitalization or death.

RESULTS

One hundred three reports and isolates were collected. Seventy-nine per cent of cases were community-acquired, 64% required hospitalization and 5% died. Cases with one or more assessed risk factor for IPD and of female sex were independent variables associated with hospitalization or death. One-third of isolates had reduced penicillin susceptibility and 96% of these represented serotypes contained in the 23-valent pneumococcal polysaccharide vaccine (PPV-23). Overall, 89% of serotypes identified are included in the PPV-23 vaccine and 88% of isolates from children under five years of age are found in the 7-valent pneumococcal conjugate vaccine (PCV-7). Forty-one per cent of cases qualified for publicly funded pneumococcal vaccine and 34% of eligible persons were vaccinated.

CONCLUSIONS

Overall, pneumococcal serotypes associated with IPD in this study closely matched serotypes included in PPV-23 products currently licensed in Canada. Most serotypes associated with IPD in children under five years of age are included in a recently licenced PCV-7. One third of isolates demonstrated reduced penicillin susceptibility, most involving serotypes included in PPV-23. Effective delivery of current public health immunization programs using PPV-23 and extending protection to infants and young children using the PCV-7 will prevent many cases of IPD.

Immunization Monitoring Program, Active: a model of active surveillance of vaccine safety

In Canada since 1993 the nation's passive system for reporting postimmunization adverse events has been supplemented by the active surveillance of inpatients at 10 to 12 pediatric referral centers, a system referred to as the Immunization Monitoring Program, Active. Participating centers are located from coast-to-coast and receive referrals from every province and territory. Approximately 20 percent of the population aged 0 to 12 years lives in the immediate vicinity of these centers. Nurse monitors at each center search for numerous target conditions, including postimmunization adverse events and vaccine-preventable infections. Vaccine safety observations have included (1) a substantial decrease in the risk of the development of febrile seizures and hypotonic-hyporesponsive episodes since the country switched from whole-cell to acellular pertussis-containing vaccines, (2) no evidence for encephalopathy resulting from the latter vaccines, (3) a generally benign outcome with postimmunization thrombocytopenia cases, and (4) an unexpectedly high rate of disseminated bacille Calmette-Guérin infections among aboriginal infants. Concomitant disease surveillance has been important for sustaining the surveillance system because few postimmunization adverse events require hospital admission.

Invasive pneumococcal infections: a clinical and microbiological analysis of 53 patients in Taiwan

OBJECTIVE

To track penicillin susceptibility among Streptococcus pneumoniae causing invasive diseases and to evaluate risk factors for antibiotic resistance.

METHODS

A retrospective study was performed in a medical center of all patients with invasive pneumococcal infections based on positive microbiological findings, confirmed by appropriate clinical and laboratory findings. MICs of penicillin and ceftriaxone were determined and interpreted by NCCLS methodology.

RESULTS

Fifty-three episodes of invasive S. pneumoniae infections (ISPI) among 22 children and 31 adults were identified. The disease patterns of ISPI were similar between children and adults, and the most common modes were pneumonia (70%) and primary bacteremia (23%). The rate of penicillin-nonsusceptible S. pneumoniae (PNSP) isolated from pediatric patients was higher than that in adult patients (95.5% vs. 54.8%, P < 0.001). This finding was correlated to prior antibiotic use that was more common in children (36.4%) than in adults (18.9%). The rate of penicillin-resistance among S. pneumoniae isolates (PRSP) was extremely high in this area: 45.5% from pediatric patients and 41.9% from adult patients. More adults (90.3%) with ISPI had major underlying diseases than children (4.5%). This may explain why adult patients tended to run an unfavorable outcome (mortality rate, 51.6% and 4.5% in adults and children, respectively), although most of the cases with empyema were children. None of the patients enrolled in this study received pneumococcal vaccination.

CONCLUSION

We suggest that vaccines be administered for young children and the elderly with major underlying diseases to prevent ISPI.

A pharmacoeconomic evaluation of 7-valent pneumococcal conjugate vaccine in Canada

The objective of this study was to evaluate the projected health benefits, costs, and cost-effectiveness of pneumococcal conjugate vaccination for infants and children aged <5 years in Canada. A health state model incorporating incidence, vaccine efficacy, costs, and transitional probabilities for the health states (well, meningitis, bacteremia, otitis media, pneumonia, and death) was constructed for a 10-year time horizon. Implementation of a pneumococcal conjugate vaccine program in Canada for each annual birth cohort of 340,000 persons observed over 10 years would be expected to save approximately 12 lives and 100,000 cases of pneumococcal disease over 10 years, resulting in total savings of $67 million (Canadian dollars [Can$]). Vaccination of healthy infants would result in net savings for society if the vaccine costs less than Can$50 per dose. Moreover, for a vaccine purchase price of Can$67.50, infant vaccination would cost society Can$79,000 per life-year gained. Pneumococcal conjugate vaccination is a potentially cost-effective means of pneumococcal disease prevention.