Preventability of invasive pneumococcal disease and assessment of current polysaccharide vaccine recommendations for adults: United States, 2001-2003

Immunization with pneumococcal elongation factor Tu enhances serotype-independent protection against Streptococcus pneumoniae infection

Vaccination is an effective strategy to prevent pneumococcal diseases. Currently, licensed vaccines include the pneumococcal polysaccharide vaccine (PPSV) and the pneumococcal conjugate vaccine (PCV), which target some of the most common of the 94 serotypes of S. pneumoniae based on their capsular composition. However, it has been reported that PPSV is not effective in children aged less than 2 years old and PCV induces serotype replacement, which means that the pneumococcal population has changed following widespread introduction of these vaccines, and the non-vaccine serotypes have increased in being the cause of invasive pneumococcal disease. Therefore, it is important that there is development of novel pneumococcal vaccines to either replace or complement current polysaccharide-based vaccines. Our previous study suggested that S. pneumoniae releases elongation factor Tu (EF-Tu) through autolysis followed by the induction of proinflammatory cytokines in macrophages via toll-like receptor 4, that may contribute to the development of pneumococcal diseases. In this study, we investigated the expression of EF-Tu in various S. pneumoniae strains and whether EF-Tu could be an antigen candidate for serotype-independent vaccine against pneumococcal infection. Western blotting and flow cytometry analysis revealed that EF-Tu is a common factor expressed on the surface of all pneumococcal strains tested, as well as intracellularly. In addition, we demonstrate that immunization with recombinant (r) EF-Tu induced the production of inflammatory cytokines and the IgG1 and IgG2a antibodies in mice, and increased the CD4⁺ T-cells proportion in splenocytes. We also reveal that anti-EF-Tu serum increased the phagocytic activity of mouse peritoneal macrophages against S. pneumoniae infection, independent of their serotypes. Finally, our results indicate that mice immunized with rEF-Tu were significantly and non-specifically protected against lethal challenges with S. pneumoniae serotypes (2 and 15A). Therefore, pneumococcal EF-Tu could be an antigen candidate for the serotype-independent vaccine against pneumococcal infection.

A pharmacist-driven academic detailing program to increase adult pneumococcal vaccination

OBJECTIVES

To describe our statewide, pharmacist-led education campaign to increase knowledge and awareness of pneumococcal immunization recommendations.

SETTING

Immunization providers and residents in the state of Rhode Island.

PRACTICE DESCRIPTION

A clinical pathway (i.e., decision-support tool) was developed to educate health professionals about appropriate indications, administration schedules, and frequently asked questions for the 2 different adult pneumococcal vaccines. Academic detailing and distribution of the clinical pathway to health professionals was conducted across Rhode Island. Community outreach activities included radio ads as well as distribution of patient handouts and wallet cards at community events.

PRACTICE INNOVATION

To our knowledge, this was the first statewide, pharmacist-driven academic detailing and community outreach campaign to promote adult pneumococcal vaccination.

EVALUATION

Academically detailed immunization providers received a 6-question survey. Pneumococcal disease rate differences between the study periods were evaluated with the use of Fisher exact tests, whereas changes in vaccination were assessed with the use of chi-square tests.

RESULTS

From November 2013 through July 2015, our academic detailers visited and distributed our vaccination pathway materials to more than 400 practice sites across Rhode Island, including 68% of community pharmacies and all adult acute care hospitals. Of the 413 surveys completed, 92% of respondents agreed that their knowledge of the pneumococcal conjugate vaccine, 13-valent and pneumococcal polysaccharide vaccine, 23-valent had improved. Pneumococcal vaccination increased significantly (absolute difference 3.9%, percentage change in proportion 5.4%; P = 0.01), and pneumococcal disease decreased significantly between the preintervention and intervention periods (-2.74/10,000 discharges [95% CI -5.15 to -0.32], P = 0.02). Invasive pneumococcal disease decreased by 21 cases per 1,000,000 population per year between the preintervention and postintervention periods (-42.25 to 0.14, P = 0.05).

CONCLUSION

Our statewide, pharmacist-driven pneumococcal vaccination educational outreach program resulted in favorable provider feedback relative to knowledge change and perceptions. Vaccination increased and pneumococcal disease decreased during the study period.

Pneumococcal DnaJ modulates dendritic cell-mediated Th1 and Th17 immune responses through Toll-like receptor 4 signaling pathway

Pneumococcal DnaJ was recently shown to be a potential protein vaccine antigen that induces strong Th1 and Th17 immune response against streptococcus pneumoniae infection in mice. However, how DnaJ mediates T cell immune response against S. pneumoniae infection has not been addressed. Here, we investigate whether DnaJ contributes to the development of T cell immunity through the activation of bone marrow-derived dendritic cells (BMDCs). We found that endotoxin-free recombinant DnaJ (rDnaJ) induced activation and maturation of BMDCs via recognition of Toll-like receptor 4 (TLR4) and activation of MAPKs, NF-κB and PI3K-Akt pathways. rDnaJ-treated BMDCs effectively stimulated naïve CD4⁺ T cells to secrete IFN-γ and IL-17A. Splenocytes from mice that were adoptively transferred with rDnaJ-pulsed BMDCs secreted higher levels of IFN-γ and IL-17A compared with those that received PBS-activated BMDCs. Splenocytes from TLR4^-/- mice immunized with rDnaJ produced lower levels of IFN-γ and IL-17A compared with those from wild type mice. Our findings indicate that DnaJ can induce Th1 and Th17 immune responses against S. pneumoniae through activation of BMDCs in a TLR4-dependent manner.

Use of Pneumococcal Disease Epidemiology to Set Policy and Prevent Disease during 20 Years of the Emerging Infections Program

This program has been a flexible platform for following trends of this disease and evaluating vaccine effectiveness.

Two decades ago, the Emerging Infections Program of the US Centers for Disease Control and Prevention implemented what seemed like a simple yet novel idea: a population- and laboratory-based surveillance system designed to identify and characterize invasive bacterial infections, including those caused by Streptococcus pneumoniae. This system, known as Active Bacterial Core surveillance, has since served as a flexible platform for following trends in invasive pneumococcal disease and studying vaccination as the most effective method for prevention. We report the contributions of Active Bacterial Core surveillance to every pneumococcal vaccine policy decision in the United States during the past 20 years.

Epidemiology of pneumococcal disease in a national cohort of older adults

Introduction

Streptococcus pneumoniae is a major cause of morbidity and mortality. We sought to describe the epidemiology of non-invasive and invasive pneumococcal disease in a national Veterans Affairs population within the United States.

Methods

We conducted a retrospective study in older patients (aged ≥50 years) with positive pneumococcal cultures from any site between 2002 and 2011. We described outpatient and inpatient pneumococcal disease incidence per 100,000 clinic visits/hospitalizations. Repeat cultures within a 30-day period were considered to represent the same episode. To describe the epidemiology of serious pneumococcal infections (bacteremia, meningitis, pneumonia), we assessed demographics, clinical characteristics, and risk factors for S. pneumoniae. Pneumonia was defined as a positive respiratory culture with a pneumonia diagnosis code. Bacteremia and meningitis were identified from positive cultures. Generalized linear mixed models were used to quantify changes over time.

Results

Over the study period, we identified 45,983 unique episodes of pneumococcal disease (defined by positive cultures). Incidence decreased significantly by 3.5% per year in outpatients and increased non-significantly by 0.2% per year in inpatients. In 2011, the outpatient and inpatient incidence was 2.6 and 328.1 infections per 100,000 clinic visits/hospitalizations, respectively. Among inpatients with serious infections, chronic disease risk factors for pneumococcal disease increased significantly each year, including respiratory disease (1.9% annually), diabetes (1.3%), and renal failure (1.0%). Overall, 30.2% of inpatients with serious infections had a pneumococcal immunization in the previous 5 years. Invasive disease (37.4% versus 34.9%, P = 0.004) and mortality (14.0% versus 12.7%, P = 0.045) were higher in non-vaccinated patients compared to vaccinated patients.

Conclusions

In our national study of older adults, the baseline health status of those with serious pneumococcal infections worsened over the study period. As the population ages and the chronic disease epidemic grows, the burden of pneumococcal disease is likely to increase thus highlighting the importance of pneumococcal vaccination.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-014-0025-y) contains supplementary material, which is available to authorized users.

Serotype-independent protection against pneumococcal infections elicited by intranasal immunization with ethanol-killed pneumococcal strain, SPY1

The 23-valent polysaccharide vaccine and the 7-valent pneumococcal conjugate vaccine are licensed vaccines that protect against pneumococcal infections worldwide. However, the incidence of pneumococcal diseases remains high in low-income countries. Whole-cell vaccines with high safety and strong immunogenicity may be a favorable choice. We previously obtained a capsule-deficient Streptococcus pneumoniae mutant named SPY1 derived from strain D39. As an attenuated live pneumococcal vaccine, intranasal immunization with SPY1 elicits broad serotype-independent protection against pneumococcal infection. In this study, for safety consideration, we inactivated SPY1 with 70% ethanol and intranasally immunized BALB/c mice with killed SPY1 plus cholera toxin adjuvant for four times. Results showed that intranasal immunization with inactivated SPY1 induced strong humoral and cellular immune responses. Intranasal immunization with inactivated SPY1 plus cholera toxin adjuvant elicited effective serotype-independent protection against the colonization of pneumococcal strains 19F and 4 as well as lethal infection of pneumococcal serotypes 2, 3, 14, and 6B. The protection rates provided by inactivated SPY1 against lethal pneumococcal infection were comparable to those of currently used polysaccharide vaccines. In addition, vaccine-specific B-cell and T-cell immune responses mediated the protection elicited by SPY1. In conclusion, the 70% ethanol-inactivated pneumococcal whole-cell vaccine SPY1 is a potentially safe and less complex vaccine strategy that offers broad protection against S. pneumoniae.

Modeling of cost effectiveness of pneumococcal conjugate vaccination strategies in U.S. older adults

BACKGROUND

The 13-valent pneumococcal conjugate vaccine (PCV13) is approved by the U.S. Food and Drug Administration for adults, but its role in older adults is unclear.

PURPOSE

To compare PCV13 strategies to currently recommended vaccination strategies in adults aged ≥65 years.

METHODS

Using a Markov model, the cost effectiveness of PCV13 and the 23-valent pneumococcal polysaccharide vaccine (PPSV23), alone or in combination, was estimated, in adults aged either 65 years or 75 years. No prior vaccination, prior vaccination, and vaccine hyporesponsiveness scenarios were examined. Pneumococcal disease rates, indirect childhood PCV13 effects, and costs were estimated using CDC Active Bacterial Core surveillance data and U.S. national databases. An expert panel estimated vaccine-related protection. A societal perspective was taken and outcomes were discounted 3% per year.

RESULTS

In those aged 65 years, single-dose PCV13 cost $11,300 per quality-adjusted life-year (QALY) gained compared to no vaccination; at ages 65 and 80 years, PCV13 cost $83,000/QALY. In those aged 75 years, single-dose PCV13 cost $62,800/QALY gained. PPSV23 cost more and was less effective than PCV13. Results were sensitive to varying vaccine effectiveness and indirect effect estimates. In hyporesponsiveness scenarios, cost-effectiveness ratios increased by 37%-78% for single-dose strategies and 29%-35% for multiple-dose strategies.

CONCLUSIONS

Single-dose PCV13 strategies are likely to be economically reasonable in older adults.

Outpatient-based pneumococcal vaccine campaign and survey of perceptions about pneumococcal vaccination in patients and doctors

PURPOSE

Despite the ready availability of pneumococcal vaccine, vaccination rates are quite low in South Korea. This study was designed to assess perceptions and awareness about pneumococcal vaccines among subjects at risk and find strategies to increases vaccine coverage rates.

MATERIALS AND METHODS

A cross sectional, community-based survey was conducted to assess perceptions about the pneumococcal vaccine at a local public health center. In a tertiary hospital, an outpatient- based pneumococcal vaccine campaign was carried out for the elderly and individuals with chronic co-morbidities from May to July of 2007.

RESULTS

Based on the survey, only 7.6% were ever informed about pneumococcal vaccination. The coverage rates of the pneumococcal vaccine before and after the hospital campaign showed an increased annual rate from 3.39% to 5.91%. The most common reason for vaccination was "doctor's advice" (53.3%). As for the reasons for not receiving vaccination, about 75% of high risk patients were not aware of the pneumococcal vaccine, which was the most important barrier to vaccination. Negative clinician's attitude was the second most common cause of non-vaccination.

CONCLUSION

Annual outpatient-based campaigns early in the influenza season may improve pneumococcal vaccine coverage rates. Doctor's advice was the most important encouraging factor for vaccination.

Invasive pneumococcal disease associated with high case fatality in India

OBJECTIVE

To study the seroepidemiology and antimicrobial resistance pattern of invasive pneumococcal disease (IPD) in older subjects who are admitted to hospitals in India.

STUDY DESIGN AND SETTING

Prospective surveillance of IPD in patients older than 18 years in seven large academic teaching hospitals in India from 1993 to 2008. All subjects who had Streptococcus pneumoniae isolated from normally sterile body fluids or were antigen positive in cerebrospinal fluid, ascitic fluid, and pleural fluid were identified as IPD cases in the study. Serotype/group (STG) and minimum inhibitory concentration for penicillin, chloramphenicol, co-trimoxazole (trimethoprim-sulfamethoxazole), erythromycin, and cefotaxime were determined.

RESULTS

A total of 1,037 adult subjects with suspected invasive bacterial infection were recruited in the study. S pneumoniae was identified from normally sterile body fluids in 449 (43.3%) subjects. Meningitis (34.3%) and pneumonia (33.9%) were the most common clinical conditions associated with IPD. The case fatality was 25-30% across all age groups. Penicillin resistance was low at 2.7% overall. Resistance to co-trimoxazole was noted to be high and increasing in the study period from 42.9% in 1993 to 85.2% in 2008 (P = 0.001). The most common STG was serotype 1, which accounted for 22.9% of all isolates. The 23-valent pneumococcal polysaccharide vaccine covered 83.3% of the STGs (49/54; 95% confidence interval: 79.7, 96.9) for patients older than 60 years.

CONCLUSION

IPD continues to be a problem in India and is associated with high case fatality in spite of treatment in the hospital setting. Penicillin resistance is currently low in India. More than 80% of invasive STGs causing disease in the elderly in India are included in the formulation of polysaccharide pneumococcal vaccine.

Immune response and protective efficacy of S9 ribosomal protein of Streptococcus pneumoniae in a model of sepsis

Vaccination is the most promising strategy to reduce the incidence of pneumococcal infection. Although there are vaccines available, all of them are based on polysaccharide antigens (conjugated or not). In addition to their high cost, those vaccines do not cover all serotypes. To overcome these hindrances, we evaluated the immunogenicity and the protective efficacy of the S9 ribosomal protein of Streptococcus pneumoniae with the aim of developing a protein-based vaccine in the future. The gene encoding the S9 ribosomal protein was cloned in pET21-a expression vector, and the recombinant S9 protein was used to immunize mice. Significantly higher levels of anti-S9 immunoglobulin G were achieved (with predominance of immunoglobulin G1) in comparison with the control. Antibodies elicited against S. pneumoniae protein extract in rabbit recognized the recombinant S9 protein by Western blot, thus demonstrating its immunogenicity. Moreover, mice immunized with recombinant S9 protein and challenged with a virulent strain of S. pneumoniae presented a significant reduction of bacteremia after 24 h of infection as compared with the control. However, in the S9-immunized mice the onset of death was insignificantly delayed, but all of them died by the fourth day postinfection.

Streptococcus pneumoniae vaccination in older adults

BACKGROUND

Streptococcus pneumoniae infections are a major cause of morbidity and mortality in older adults. Vaccination in older adults is intended to prevent S pneumoniae infections, yet little information is available regarding its efficacy in this patient population.

OBJECTIVE

The aim of this article was to review the current literature to determine the efficacy and tolerability of S pneumoniae vaccination in older adults.

METHODS

PubMed (1950-present) and EMBASE (1974-present) were searched using the search terms Streptococcus pneumoniae immunization, pneumococcus immunization, pneumococcus vaccine, and aged. Additional articles were identified from the reference lists of included studies. Studies were included if they reported information in older (55-<65 years) and elderly (≥65 years) adults and were related to at least 1 of the following topics: epidemiology of S pneumoniae, estimates of vaccine coverage, recommendations for vaccination, tolerability, and efficacy and/or effectiveness of vaccination against S pneumoniae.

RESULTS

Six randomized controlled trials and 18 observational studies that evaluated the efficacy of pneumococcal vaccination in older and elderly adults were reviewed. Findings from evaluations of efficacy, as measured by clinical outcomes and immunogenicity, in older adults have been conflicting, with some subsets of prospective, well-controlled studies finding little benefit, whereas findings from several retrospective studies have suggested significant benefit. This discord may have been a result of the limited power of the prospective subanalyses to detect significant differences.

CONCLUSIONS

In light of the potential clinical benefit and few reports of serious adverse events, vaccination in older adults is likely warranted. Prospective, well-controlled studies are needed to better quantitatively evaluate the benefit of pneumococcal vaccine in older adults.

Streptococcus pneumoniae clonal complex 199: genetic diversity and tissue-specific virulence

Streptococcus pneumoniae is an important cause of otitis media and invasive disease. Since introduction of the heptavalent pneumococcal conjugate vaccine, there has been an increase in replacement disease due to serotype 19A clonal complex (CC)199 isolates. The goals of this study were to 1) describe genetic diversity among nineteen CC199 isolates from carriage, middle ear, blood, and cerebrospinal fluid, 2) compare CC199 19A (n = 3) and 15B/C (n = 2) isolates in the chinchilla model for pneumococcal disease, and 3) identify accessory genes associated with tissue-specific disease among a larger collection of S. pneumoniae isolates. CC199 isolates were analyzed by comparative genome hybridization. One hundred and twenty-seven genes were variably present. The CC199 phylogeny split into two main clades, one comprised predominantly of carriage isolates and another of disease isolates. Ability to colonize and cause disease did not differ by serotype in the chinchilla model. However, isolates from the disease clade were associated with faster time to bacteremia compared to carriage clade isolates. One 19A isolate exhibited hypervirulence. Twelve tissue-specific genes/regions were identified by correspondence analysis. After screening a diverse collection of 326 isolates, spr0282 was associated with carriage. Four genes/regions, SP0163, SP0463, SPN05002 and RD8a were associated with middle ear isolates. SPN05002 also associated with blood and CSF, while RD8a associated with blood isolates. The hypervirulent isolate's genome was sequenced using the Solexa paired-end sequencing platform and compared to that of a reference serotype 19A isolate, revealing the presence of a novel 20 kb region with sequence similarity to bacteriophage genes. Genetic factors other than serotype may modulate virulence potential in CC199. These studies have implications for the long-term effectiveness of conjugate vaccines. Ideally, future vaccines would target common proteins to effectively reduce carriage and disease in the vaccinated population.

Immunization with DnaJ (hsp40) could elicit protection against nasopharyngeal colonization and invasive infection caused by different strains of Streptococcus pneumoniae

Increasing mortality, morbidity and economic costs have been paid to pneumococcal diseases every year. Currently, vaccination is the most promising strategy to reduce the occurrence of pneumococcal infection. In this study, we investigated the protective efficacy of immunization with recombinant DnaJ (hsp40) protein against infections of different serotypes of Streptococcus pneumoniae. We demonstrated that mucosal immunization with DnaJ antigen could induce both systemic and mucosal antibodies for DnaJ and stimulate the release of high levels of IL-10, IFN-γ and IL-17A. Moreover, this mucosal vaccination could reduce nasal or lung colonization of pneumococcus and elicit protection against different serotypes of invasive pneumococcal infections. As well, we found that intraperitoneal immunization with DnaJ could also protect against invasive infections caused by different serotypes of pneumococcus, and passive immunization with antibodies specific for DnaJ confirmed that this protection was antibody-mediated. Our results therefore support the potential of DnaJ as a conserved pneumococcal protein vaccine.

Immunization with a ZmpB-based protein vaccine could protect against pneumococcal diseases in mice

Zinc metalloprotease B (ZmpB) is present in all isolated pneumococcal strains and contributes to the pathogenesis of pneumococcal infection. In this study, recombinant ZmpB was cloned and expressed in Escherichia coli. The expression of ZmpB by different pneumococcal strains was detectable by Western blotting with antisera raised to recombinant ZmpB. Flow cytometry analysis demonstrated that anti-ZmpB polyclonal antibodies could bind to the cell surface of the pneumococcal strains analyzed. Both recombinant ZmpB protein and anti-ZmpB polyclonal antibodies significantly inhibited the adhesion of Streptococcus pneumoniae D39 to A549 cells. In mouse models, mucosal immunization with recombinant ZmpB could significantly reduce pneumococcal lung colonization caused by S. pneumoniae serotypes 19F and 14 and significantly increase mice survival times following invasive pneumococcal challenge with different pneumococcal strains, including serotypes 2, 3, 6B, and 14. Furthermore, intraperitoneal immunization with recombinant ZmpB in combination with the recombinant pneumolysin mutant (DeltaA146 Ply) and heat shock protein 40 (DnaJ) could enhance the protection against pneumococcal infection compared to protection provided by single-protein antigens. Passive immunization with hyperimmune antisera against these three antigens also demonstrated that the combination of three hyperimmune antisera could provide better protection than single antisera. Taken together, our results suggest that ZmpB is a good candidate pneumococcal vaccine antigen.

Population-based surveillance for invasive pneumococcal disease in homeless adults in Toronto

Background

Identification of high-risk populations for serious infection due to S. pneumoniae will permit appropriately targeted prevention programs.

Methods

We conducted prospective, population-based surveillance for invasive pneumococcal disease and laboratory confirmed pneumococcal pneumonia in homeless adults in Toronto, a Canadian city with a total population of 2.5 M, from January 1, 2002 to December 31, 2006.

Results

We identified 69 cases of invasive pneumococcal disease and 27 cases of laboratory confirmed pneumococcal pneumonia in an estimated population of 5050 homeless adults. The incidence of invasive pneumococcal disease in homeless adults was 273 infections per 100,000 persons per year, compared to 9 per 100,000 persons per year in the general adult population. Homeless persons with invasive pneumococcal disease were younger than other adults (median age 46 years vs 67 years, P<.001), and more likely than other adults to be smokers (95% vs. 31%, P<.001), to abuse alcohol (62% vs 15%, P<.001), and to use intravenous drugs (42% vs 4%, P<.001). Relative to age matched controls, they were more likely to have underlying lung disease (12/69, 17% vs 17/272, 6%, P = .006), but not more likely to be HIV infected (17/69, 25% vs 58/282, 21%, P = .73). The proportion of patients with recurrent disease was five fold higher for homeless than other adults (7/58, 12% vs. 24/943, 2.5%, P<.001). In homeless adults, 28 (32%) of pneumococcal isolates were of serotypes included in the 7-valent conjugate vaccine, 42 (48%) of serotypes included in the 13-valent conjugate vaccine, and 72 (83%) of serotypes included in the 23-valent polysaccharide vaccine. Although no outbreaks of disease were identified in shelters, there was evidence of clustering of serotypes suggestive of transmission of pathogenic strains within the homeless population.

Conclusions

Homeless persons are at high risk of serious pneumococcal infection. Vaccination, physical structure changes or other program to reduce transmission in shelters, harm reduction programs to reduce rates of smoking, alcohol abuse and infection with bloodborne pathogens, and improved treatment programs for HIV infection may all be effective in reducing the risk.

Age, revaccination, and tolerance effects on pneumococcal vaccination strategies in the elderly: a cost-effectiveness analysis

Optimal pneumococcal polysaccharide vaccination (PPV) policy is unknown for cohorts aged > or =65 years. Using a Markov model, we estimated the cost-effectiveness of single- and multiple-dose PPV strategies in 65-, 75-, and 80-year-old cohorts. PPV at age 65 cost $26,100 per QALY (quality adjusted life years) gained. Vaccination at ages 75 and 80 cost $71,300-75,800 per QALY; revaccination strategies cost more. When prior vaccination and loss of vaccine effectiveness due to tolerance are assumed, cost-effectiveness ratios increase substantially. Single-dose PPV is worth considering in patients aged 65-80 from clinical and economic standpoints. Revaccination strategies for the elderly are less cost-effective, particularly when prior vaccination and vaccine tolerance are considered.

Caseinolytic protease: a protein vaccine which could elicit serotype-independent protection against invasive pneumococcal infection

Invasive pneumococcal diseases incur significant mortality, morbidity and economic costs. The most effective strategy currently available to reduce the burden of these diseases is vaccination. In this study, we evaluated the protective efficacy of immunizing mice with caseinolytic protease (ClpP) protein antigen whose gene sequences were shown to be highly conserved in different strains of Streptococcus pneumoniae in an invasive-disease model (intraperitoneal infection model), and protection against invasive challenge with 12 different serotypes of S. pneumoniae was assessed in two murine strains. Our findings demonstrated that active immunization with ClpP and passive immunization with antibodies specific for ClpP could elicit serotype-independent protection effectively against invasive pneumococcal infection. Therefore, to our knowledge, this study is the first report that immunization with single pneumococcal ClpP protein antigen could protect against such broad-range pneumococal strains, which thus supports the development of ClpP as a human penumococcal vaccine.

Tobacco use increases susceptibility to bacterial infection

Active smokers and those exposed to secondhand smoke are at increased risk of bacterial infection. Tobacco smoke exposure increases susceptibility to respiratory tract infections, including tuberculosis, pneumonia and Legionnaires disease; bacterial vaginosis and sexually transmitted diseases, such as chlamydia and gonorrhoea; Helicobacter pylori infection; periodontitis; meningitis; otitis media; and post-surgical and nosocomial infections. Tobacco smoke compromises the anti-bacterial function of leukocytes, including neutrophils, monocytes, T cells and B cells, providing a mechanistic explanation for increased infection risk. Further epidemiological, clinical and mechanistic research into this important area is warranted.

Pneumococcal vaccination in general internal medicine practice: current practice and future possibilities

BACKGROUND

Pneumococcal vaccine (PPV) is recommended for adults >or=65 years and those with chronic illness, but there are potential advantages of universal vaccination of adults age 50-64 years.

OBJECTIVE

To assess reported (1) recommendations and administration practices of general internists for PPV, (2) barriers to vaccination, and (3) willingness to expand vaccination to all adults >or=50 years.

METHODS

National survey of general internists representative of the American College of Physicians.

RESULTS

Response rate was 74% (N = 326). Although 99% reported giving PPV, less than 20% used a computerized database to identify eligible patients by age or diagnoses and only 6% recalled patients. Major barriers included acute problems taking precedence over preventive care (39%), difficulty determining vaccination history (30%), not thinking of it/not a priority (20%), and inadequate reimbursement for vaccine (19%). If ACIP expanded recommendations, 60% would definitely and 37% would probably institute this change.

CONCLUSIONS

Most general internists reported giving PPV, but delivery was hindered by competing demands, lack of systems to identify patients needing vaccination, and reimbursement issues. Barriers might be decreased by a policy of universal vaccination of adults >or=50 years, and the majority of physicians reported they would follow such a recommendation if it were made.

Invasive pneumococcal infections among persons with and without underlying medical conditions: implications for prevention strategies

Background

The 23-valent pneumococcal polysaccharide vaccine (PPV23) is recommended for persons aged < 65 years with chronic medical conditions. We evaluated the risk and mortality from invasive pneumococcal disease (IPD) among persons with and without the underlying medical conditions which are considered PPV23 indications.

Methods

Population-based data on all episodes of IPD (positive blood or cerebrospinal fluid culture) reported by Finnish clinical microbiology laboratories during 1995–2002 were linked to data in national health care registries and vital statistics to obtain information on the patient's preceding hospitalisations, co-morbidities, and outcome of illness.

Results

Overall, 4357 first episodes of IPD were identified in all age groups (average annual incidence, 10.6/100,000). Patients aged 18–49 and 50–64 years accounted for 1282 (29%) and 934 (21%) of IPD cases, of which 372 (29%) and 427 (46%) had a current PPV23 indication, respectively. Overall, 536 (12%) IPD patients died within one month of first positive culture. Persons aged 18–64 years accounted for 254 (47%) of all deaths (case-fatality proportion, 12%). Of those who died 117 (46%) did not have a vaccine indication. In a survival model, patients with alcohol-related diseases, non-haematological malignancies, and those aged 50–64 years were most likely to die.

Conclusion

In the general population of non-elderly adults, almost two-thirds of IPD and half of fatal cases occurred in persons without a recognised PPV23 indication. Policymakers should consider additional prevention strategies such as lowering the age of universal PPV23 vaccination and introducing routine childhood pneumococcal conjugate immunisation which could provide substantial health benefits to this population through indirect vaccine effects.

Alternative strategies for adult pneumococcal polysaccharide vaccination: a cost-effectiveness analysis

Pneumococcal polysaccharide vaccination (PPV) to prevent invasive pneumococcal disease (IPD) is recommended at age 65 for most persons in the US. We used a Markov model to examine alternative PPV strategies, finding that vaccination at ages 50 and 65 prevented more IPD than present vaccination policies; four decennial vaccinations were most effective. The present vaccination policy costs $3341/QALY gained, vaccinations at 50/65 cost $23,120/QALY and four vaccinations (50/60/70/80) cost $54,451/QALY; results were sensitive to vaccine uptake assumptions, with current policy no longer favored at present vaccination rates. PPV at ages 50/65 may be clinically and, depending on cost-effectiveness criterion used, economically favored over present vaccination recommendations.

In vitro and in vivo antibacterial activities of DC-159a, a new fluoroquinolone

DC-159a is a new 8-methoxy fluoroquinolone that possesses a broad spectrum of antibacterial activity, with extended activity against gram-positive pathogens, especially streptococci and staphylococci from patients with community-acquired infections. DC-159a showed activity against Streptococcus spp. (MIC(90), 0.12 microg/ml) and inhibited the growth of 90% of levofloxacin-intermediate and -resistant strains at 1 microg/ml. The MIC 90s of DC-159a against Staphylococcus spp. were 0.5 microg/ml or less. Against quinolone- and methicillin-resistant Staphylococcus aureus strains, however, the MIC 90 of DC-159a was 8 microg/ml. DC-159a was the most active against Enterococcus spp. (MIC 90, 4 to 8 microg/ml) and was more active than the marketed fluoroquinolones, such as levofloxacin, ciprofloxacin, and moxifloxacin. The MIC 90s of DC-159a against Haemophilus influenzae, Moraxella catarrhalis, and Klebsiella pneumoniae were 0.015, 0.06, and 0.25 microg/ml, respectively. The activity of DC-159a against Mycoplasma pneumoniae was eightfold more potent than that of levofloxacin. The MICs of DC-159a against Chlamydophila pneumoniae were comparable to those of moxifloxacin, and DC-159a was more potent than levofloxacin. The MIC 90s of DC-159a against Peptostreptococcus spp., Clostridium difficile, and Bacteroides fragilis were 0.5, 4, and 2 microg/ml, respectively; and among the quinolones tested it showed the highest level of activity against anaerobic organisms. DC-159a demonstrated rapid bactericidal activity against quinolone-resistant Streptococcus pneumoniae strains both in vitro and in vivo. In vitro, DC-159a showed faster killing than moxifloxacin and garenoxacin. The bactericidal activity of DC-159a in a murine muscle infection model was revealed to be superior to that of moxifloxacin. These activities carried over to the in vivo efficacy in the murine pneumonia model, in which treatment with DC-159a led to bactericidal activity superior to those of the other agents tested.

Changing characteristics of invasive pneumococcal disease in Metropolitan Atlanta, Georgia, after introduction of a 7-valent pneumococcal conjugate vaccine

BACKGROUND

The rate of invasive pneumococcal disease (IPD) has decreased among both immunized children and nonimmunized adults since the licensure of a heptavalent pneumococcal conjugate vaccine (PCV7) for use in infants in the United States in 2000.

METHODS

Temporal trends in IPD incidence, clinical syndromes, and underlying conditions were analyzed using active laboratory- and population-based surveillance data from the Centers for Disease Control and Prevention-sponsored Georgia Emerging Infections Program for the 20-county Metropolitan Atlanta, Georgia, for the period of July 1997 through June 2004. P values were determined by test for trend.

RESULTS

Since 2000, there have been significant decreases in the rates of invasive pneumococcal pneumonia (relative risk [RR], 0.80; P=.002) and meningitis (RR, 0.41; P=.003) in adults and for primary bacteremia, invasive pneumonia, and meningitis in children (RR, 0.16 [P<.001], 0.60 [P=.003], and 0.70 [P=.009], respectively). Among human immunodeficiency virus-infected persons, there were significant decreases in the overall rates of IPD (decrease of 43%; P<.001) and invasive pneumonia (decrease of 44%; P<.001) since 2000-2001, although the rate of IPD increased significantly (increase of 53%; P=.022) among patients with acquired immunodeficiency syndrome. There was a concurrent increase in the proportion of adults aged > or = 40 years with underlying comorbidities. Rates of non-PCV7 serotypes increased 1.61-fold and 1.28-fold from 2000-2001 to 2003-2004 in children and adults (P=.005 for both).

CONCLUSIONS

The decreasing incidence of IPD in Atlanta since 2000-2001 was associated with decreases in cases of pneumonia and meningitis in adult and pediatric subjects and in cases of primary bacteremia in children. The burden of serotype-replacement disease remained small. Adults with comorbidities represent a growing proportion of patients with IPD.

Use of Pharmacodynamic Principles to Optimise Dosage Regimens for Antibacterial Agents in the Elderly

Throughout most of the world we are witnessing an ever increasing number of aged people as a percentage of the general population. In the coming years, the unique spectrum of infections presented by an elderly population, particularly those in long-term care facilities, will challenge our ability to maintain an effective battery of antibacterials. The pharmacokinetic parameters of most antibacterial agents are altered when assessed in the elderly due in part to non-pathological physiological changes. The inability to clear a drug from the body due to declining lung, kidney/bladder, gastrointestinal and circulatory efficiency can cause accumulation in the body of drugs given in standard dosages. While this may have the potential benefit of achieving therapeutic concentrations at a lower dose, there is also a heightened risk of attaining toxic drug concentrations and an increased chance of unfavourable interactions with other medications. Pharmacodynamic issues in the elderly are related to problems that arise from treating elderly patients who may have a history of previous antibacterial treatment and exposure to resistant organisms from multiple hospitalisations. Furthermore, the elderly often acquire infections in tandem with other common disease states such as diabetes mellitus and heart disease. Thus, it is essential that optimised dosage strategies be designed specifically for this population using pharmacodynamic principles that take into account the unique circumstances of the elderly. Rational and effective dosage and administration strategies based on pharmacodynamic breakpoints and detailed understanding of the pharmacokinetics of antibacterials in the elderly increase the chances of achieving complete eradication of an infection in a timely manner. In addition, this strategy helps prevent selection of drug-resistant bacteria and minimises the toxic effects of antibacterial therapy in the elderly patient.