Childhood Invasive Bacterial Disease in Kathmandu, Nepal (2005-2013)

BACKGROUND

Invasive bacterial disease (IBD; including pneumonia, meningitis, sepsis) is a major cause of morbidity and mortality in children in low-income countries.

METHODS

We analyzed data from a surveillance study of suspected community-acquired IBD in children <15 years of age in Kathmandu, Nepal, from 2005 to 2013 before introduction of pneumococcal conjugate vaccines (PCV). We detailed the serotype-specific distribution of invasive pneumococcal disease (IPD) and incorporated antigen and PCR testing of cerebrospinal fluid (CSF) from children with meningitis.

RESULTS

Enhanced surveillance of IBD was undertaken during 2005-2006 and 2010-2013. During enhanced surveillance, a total of 7956 children were recruited of whom 7754 had blood or CSF culture results available for analysis, and 342 (4%) had a pathogen isolated. From 2007 to 2009, all 376 positive culture results were available, with 259 pathogens isolated (and 117 contaminants). Salmonella enterica serovar Typhi was the most prevalent pathogen isolated (167 cases, 28% of pathogens), followed by Streptococcus pneumoniae (98 cases, 16% pathogens). Approximately, 73% and 78% of pneumococcal serotypes were contained in 10-valent and 13-valent PCV, respectively. Most cases of invasive pneumococcal disease (IPD) were among children ≥5 years of age from 2008 onward. Antigen and PCR testing of CSF for pneumococci, Haemophilus influenzae type b and meningococci increased the number of these pathogens identified from 33 (culture) to 68 (culture/antigen/PCR testing).

CONCLUSIONS

S. enterica serovar Typhi and S. pneumoniae accounted for 44% of pathogens isolated. Most pneumococcal isolates were of serotypes contained in PCVs. Antigen and PCR testing of CSF improves sensitivity for IBD pathogens.

Stable Incidence of Invasive Pneumococcal Disease in Children in Northern France From 2014 Through 2018

BACKGROUND

The 13-valent pneumococcal conjugate vaccine (PCV13) has been recommended in France since June 2010. The aim of this study was to evaluate the trends in the incidence of invasive pneumococcal disease (IPD) resulting in hospitalization of children younger than 18 years of age, to identify the vaccination status of these patients and to analyze the serotypic evolution of the pneumococci involved in the various types of IPD.

METHODS

This multicenter retrospective study reviewed all admissions of children younger than 18 years of age for IPD from 2014 through 2018 in all hospitals with a pediatric or neonatal unit in northern France. Data completeness was obtained by matching 3 independent databases. The incidence of IPD resulting in hospitalization was calculated per age group. The clinical course and the vaccine and nonvaccine types were described overall and by the IPD type.

RESULTS

One hundred thirty cases of IPD were identified: 51 with bacteremia, 45 meningitis, 28 pneumonia or pleuropneumonia and 6 arthritis. The IPD incidence ranged from 2.4 to 3.0/100,000 in children under 18 years of age (95% confidence intervals, 1.4-3.3 and 1.9-4.1, respectively), and from 9.5 to 15.9/100,000 in children under 2 years of age, with no significant differences over time. Nonvaccine types were predominant (81%), mainly 24F, 23B and 10A. Vaccine serotype 3 was involved in 10 cases of IPD, 2 of which were in correctly vaccinated children. Two cases of IPD could have been prevented by vaccination. Neurologic sequelae affected 26% of these children (62% of those with meningitis). Six children died from IPD (5%).

CONCLUSION

The incidence of IPD resulting in hospitalization remained stable in northern France during the study period, with no significant increase in nonvaccine types. Further surveillance is needed to adjust the vaccination strategy if necessary.

Serum levels of anti-PspA and anti-PspC IgG decrease with age and do not correlate with susceptibility to experimental human pneumococcal colonization

Older adults are at increased risk of pneumococcal disease. This work aims to evaluate whether there is any decrease in serum IgG against variants of the antigens Pneumococcal surface protein A (PspA) and Pneumococcal surface protein C (PspC) in healthy adults with increasing age. Levels of IgG against PspA and PspC variants were determined by ELISA in serum samples comparing volunteers 18–30 years of age with volunteers who were 50–70+ before and after an experimental pneumococcal colonization challenge. The serotype 6B strain used in the challenge belongs to a minor group of pneumococcal isolates expressing two PspC variants. There was a decrease in levels of IgG with increasing age for the most common PspA variants and for all PspC variants analyzed. No correlation was found between basal levels of IgG against these antigens and protection against colonization. There was an increase in levels of IgG against PspA variants that are more cross-reactive with the variant expressed by the challenge strain post challenge in younger individuals who became colonized. Since the challenge strain used in our study expresses two different PspC variants, an increase in serum IgG against all PspC variants tested was observed in younger individuals who became colonized. For some of the antigen variants tested, a decrease in serum IgG was observed in young volunteers who were challenged but did not become colonized. Serum IgG antibodies against PspA and PspC variants thus decrease with age in healthy adults, but there is no correlation between levels of IgG against these antigens and protection against human experimental colonization. Though no correlation between naturally induced serum IgG antibodies against PspA and PspC and protection against colonization was observed, these results do not rule out the protective potential of these antigens as vaccines against pneumococcal infections.

A Retrospective Study of the Impact of Pneumococcal Conjugate Vaccine-13 Immunization in a Northern Israel Hospital

BACKGROUND

The introduction of pneumococcal conjugate vaccine-13 (PCV-13) has reduced the burden of invasive pneumococcal disease.

OBJECTIVES

To characterize true positive blood cultures of children who presented to our hospital following implementation of the PCV-13 vaccine.

METHODS

A retrospective study was conducted on positive blood cultures of children presenting with fever from 2010-2017. Subjects were divided into two age groups: a younger group 3-36 months and an older group 3-18 years. Patients were classified as either having or not having a focus of infection at the time of their bacteremia. Pneumococcal isolates were typed at Israel's Streptococcal Reference Laboratory.

RESULTS

The samples included 94 true positive blood cultures. Focal infection with concomitant bacteremia was more common than bacteremia without a focus both overall: 67/94 (71%) vs. 27/94 (28.7%), P <0.001 as well as in the two groups: 32/48 (66%) vs. 16/48 (33%), P = 0.02 in the younger group and 35/46 (76%) vs. 11/46 (24%), P = 0.001 in the older group. Streptococcus pneumoniae was the most common pathogen overall, 27/94 (29%), and in the younger group, 21/48 (44%), but rare in the older group, 6/46 (13%). In the latter, Brucella species predominated, 12/46 (26%), along with Staphylococcus aureus 12/46 (26%).

CONCLUSIONS

Our findings are consistent with other studies reporting decreased pneumococcal bacteremia, bacteremia primarily accompanying focal infection, and changing etiological agents among PCV-13-vaccinated children. Brucella species was prominent in older children with osteoarticular infections. Ongoing surveillance is warranted to better understand the implications of PCV-13.

The shifting epidemiology and serotype distribution of invasive pneumococcal disease in Ontario, Canada, 2007-2017

Background

Ontario, Canada introduced a publicly-funded 13-valent pneumococcal conjugate vaccine (PCV13) for infants in 2010, replacing the 10-valent (PCV10, 2009–2010) and the 7-valent (PCV7, 2005–2009) conjugate vaccine programs; a 23-valent pneumococcal polysaccharide vaccine (PPV23) has been available for older adults since 1996. We examined the epidemiology and serotype distribution of invasive pneumococcal disease (IPD) in Ontario in the context of provincial immunization programs.

Methods

We included confirmed IPD cases reported in Ontario between 2007 and 2017. We grouped serotypes according to Ontario’s current immunization program (PCV13, PPV23, and non-vaccine-preventable) and calculated incidence rates (per 100,000 population) using population data.

Results

Between 2007 and 2017, annual incidence of IPD in Ontario ranged between 7.3 and 9.7/100,000 per year. Measures of illness severity were high throughout the period of surveillance. After PCV13 program implementation in 2010, incidence due to PCV13 serotypes decreased significantly across all age groups, with the greatest reductions in children <5 years and adults ≥65 years. Conversely, incidence due to PPV23 unique serotypes increased significantly between 2007 and 2017, with the greatest increases observed in adults 50–64 years (1.4 to 3.5/100,000) and ≥65 years (2.3 to 7.2/100,000). Similar increases were observed in incidence due to non-vaccine-preventable serotypes among all age groups, except infants <1 year. Within specific serotypes, incidence due to serotypes 3 (0.42 to 0.98/100,000) and 22F (0.31 to 0.72/100,000) increased significantly between 2007 and 2017, while incidence due to serotypes 19A and 7F decreased significantly during the PCV13 period (2010–2017).

Conclusions

Eight years after PCV13 implementation in Ontario, our data suggest both direct and indirect effects on serotype-specific incidence in young children and older adults. However, overall provincial rates have remained unchanged, and IPD continues to be a severe burden on the population. The rising incidence of IPD due to PPV23 unique and non-vaccine-preventable serotypes, and the growing burden of serotypes 3 and 22F, require further study.

Population Pharmacokinetic Modeling and Probability of Target Attainment Analyses in Asian Patients With Community-Acquired Pneumonia Treated With Ceftaroline Fosamil

Efficacy of ceftaroline fosamil, the prodrug of the active metabolite ceftaroline, was demonstrated in a phase 3 study of hospitalized Asian patients with Pneumonia Outcomes Research Team (PORT) risk class III-IV community-acquired pneumonia (NCT01371838). The objectives of the current analysis were to expand an existing ceftaroline and ceftaroline fosamil population pharmacokinetic (PK) model with data from this phase 3 study and a phase 1 study (NCT01458743) assessing ceftaroline PK in healthy Chinese volunteers and to evaluate the probability of PK/pharmacodynamic (PK/PD) target attainment (PTA) in Asian patients with community-acquired pneumonia (CAP) treated with ceftaroline fosamil. The ceftaroline plasma concentration-time course was simulated for 5000 Asian patients with CAP for different renal function subgroups using the final model. PTA was calculated for Streptococcus pneumoniae, Staphylococcus aureus, and non-extended-spectrum β-lactamase-producing Enterobacteriaceae. PTA was also evaluated for ceftaroline MIC90 values of isolates collected from Asia-Pacific surveillance studies (2012-2014) and for EUCAST and FDA/CLSI ceftaroline susceptibility break points. The final model reasonably described the ceftaroline PK. Race was not found to be a significant covariate impacting ceftaroline PK, suggesting similar ceftaroline PK in Asian and Western populations when corrected for body weight. High PTAs (90%-100%) were predicted for Asian patients with CAP treated with ceftaroline fosamil, covering MIC90 values of target CAP pathogens from the region. Similarly, >90% PTAs were predicted at EUCAST and FDA/CLSI clinical break points for these pathogens. These results support the use of the ceftaroline fosamil dosing regimens approved in Europe and the United States in Asian patients with PORT III-IV CAP.

Epidemiology of invasive pneumococcal disease in indigenous and non-indigenous adults in northwestern Ontario, Canada, 2006-2015

BACKGROUND

Despite the use of pneumococcal vaccines, indigenous populations are consistently disproportionately affected by invasive pneumococcal disease (IPD). With recent changes in Ontario's provincial pneumococcal vaccination program, we sought to evaluate the epidemiology and burden of IPD in northwestern Ontario (NWO) Canada - a region that contains a substantial (19.2%) indigenous population.

METHODS

We retrospectively reviewed all adult cases of IPD that were reported to the Thunder Bay District Health Unit, in Thunder Bay, Ontario, Canada, over a 10-year period (2006-2015). Patients admitted to the Thunder Bay Regional Health Sciences Centre with IPD had their charts reviewed to abstract clinical data. Statistical analysis, including incidence rates of IPD, was performed.

RESULTS

Two hundred sixty-two cases of IPD occurred over the 10-year observation period and clinical data was available for 182 cases. Fifty-three of 182 (29.1%) patients were indigenous. 73 of 182 (40.1%) of patients were immunocompromised. Indigenous patients with IPD were more likely to be immunocompromised than non-indigenous patients (p < 0.001). Serotype data was available for 159 cases of IPD; PCV7, PCV13, and PPV23 covered 5.7%, 28.3%, and 79.2% of isolates, respectively, while 29 (20.8%) were non-vaccine serotypes. The annual incidence rate of IPD ranged from 8.9 to 25.9 per 100,000 among adults 18-64 years old; among adults 65 years of age and older the annual incidence of IPD ranged from 18.5 to 60.7 per 100,000.

CONCLUSION

Among adults in NWO, Canada, there is a high incidence of IPD. Immunocompromised indigenous adults in NWO may benefit from pneumococcal vaccination coverage. Emerging non-vaccine serotypes of Streptococcus pneumoniae warrant the consideration of the provincial pneumococcal vaccination program.

Pharmacokinetic and Pharmacodynamic Analyses To Determine the Optimal Fixed Dosing Regimen of Iclaprim for Treatment of Patients with Serious Infections Caused by Gram-Positive Pathogens

Iclaprim is a bacterial dihydrofolate reductase inhibitor that is currently being evaluated in two phase 3 trials for the treatment of patients with acute bacterial skin and skin structure infections (ABSSSI). Prior animal infection model studies suggest that the pharmacokinetic/pharmacodynamic (PK/PD) drivers for efficacy are area under the concentration-time curve from 0 to 24 h at steady state (AUC0-24ss), AUC/MIC, and time above the MIC during the dosing interval (T > MIC), while QTc prolongation was associated with the maximal concentration at steady state (Cmaxss) in a thorough QTc phase 1 study. Using PK data collected from 470 patients from the previously conducted phase 3 complicated skin and skin structure infection (cSSSI) trials, population PK modeling and Monte Carlo simulation (MCS) were used to identify a fixed iclaprim dosage regimen for the ongoing phase 3 ABSSSI studies that maximizes AUC0-24ss, AUC/MIC, and T > MIC while minimizing the probability of a Cmaxss of ≥800 ng/ml relative to the values for the previously employed cSSSI regimen of 0.8 mg/kg of body weight infused intravenously over 0.5 h every 12 h. The MCS analyses indicated that administration of 80 mg as a 2-h infusion every 12 h provides 28%, 28%, and 32% increases in AUC0-24ss, AUC/MIC, and T > MIC, respectively, compared to values for the 0.8-mg/kg cSSSI regimen, while decreasing the probability of a Cmaxss of ≥800 ng/ml, by 9%. Based on PK/PD analyses, 80 mg iclaprim administered over 2 h every 12 h was selected as the dosing scheme for subsequent phase 3 clinical trials.

Blood-Brain Barrier and Intrathecal Immune Response in patients with neuroinfections

Cerebrospinal fluid/serum albumin ratio is one of the most informative parameters for blood-brain barrier (BBB) integrity in cases of central nervous system (CNS) infectious diseases. Normally, CNS albumin concentration is a function of diffusion processes along with CSF drainage and resorption. In pathological processes CSF albumin levels are dependent only on the rate of CSF drainage resulting in non-linear reciprocal changes of albumin quotient (Qalb). IgG, IgA and IgM concentrations both in CSF and serum can be compared to Qalb, thus determining the intrathecal immune response. The aim of the study was to detect BBB permeability impairment and the intrathecal immune response in patients with CNS infections with various etiologies. CSF/serum ratios were calculated and related to IgG IgA and IgM concentrations in CSF and blood serum. The results were integrated and presented by Reibergrams. The results demonstrated typical patterns which prove albumin to be the main modulator of protein dynamics and at the same time explicates the complex pathophysiological mechanisms involved in BBB disruption and intrathecal immune response in CNS infections. The diagnostic model presented in our study seeks to explain the observations of meningitis and meningoencephalitis pathophysiology and points out the mandatory cooperation between clinicians and laboratory for accurate diagnosis and proper treatment.

Proteomic variation and diversity in clinical Streptococcus pneumoniae isolates from invasive and non-invasive sites

Streptococcus pneumoniae is responsible for a variety of invasive and non-invasive human infections. There are over 90 serotypes of S. pneumoniae differing in their ability to adapt to the different niches within the host. Two-dimensional gel electrophoresis was used to discriminate clinical S. pneumoniae isolates recovered from either blood cultures (invasive site isolates) or other sites, including sputum, tracheal aspirate, ear, eye and skin swabs (non-invasive site isolates). Global protein expression profiles for five invasive site and six non-invasive site isolates representing five different serotypes (serotypes 4, 6, 9, 14 and 23) were obtained for each isolate and combined into a single data set using Progenesis SameSpots^™ software. One-hundred and eighty six protein spots (39% of the protein spots in the dataset) differed significantly (ANOVA, p<0.05) in abundance between the invasive site (101 upregulated protein spots) and non-invasive site (85 upregulated protein spots) isolates. Correlations between the bacterial proteomes and their sites of isolation were determined by Principal Component Analysis (PCA) using the significantly different protein spots. Out of the 186 variable protein spots, 105 exhibited a serotype-associated pattern of variability. The expression of the remaining 81 protein spots was concluded to be uniquely linked to the site of bacterial isolation. Mass spectrometry was used to identify selected protein spots that showed either constant or differential abundance levels. The identified proteins had a diverse range of functions including, capsule biogenesis, DNA repair, protein deglycation, translation, stress response and virulence as well as amino acid, carbohydrate, lipid and nucleotide metabolism. These findings provide insight on the proteins that contribute towards the adaptation of the bacteria to different sites within the host.

Molecular Detection of Streptococcus pneumoniae on Dried Blood Spots from Febrile Nigerian Children Compared to Culture

Background

Nigeria has one of the highest burdens of pneumococcal disease in the world, but accurate surveillance is lacking. Molecular detection of infectious pathogens in dried blood spots (DBS) is an ideal method for surveillance of infections in resource-limited settings because of its low cost, minimal blood volumes involved, and ease of storage at ambient temperature. Our study aim was to evaluate a Streptococcus pneumoniae real-time polymerase chain reaction (rt-PCR) assay on DBS from febrile Nigerian children on Whatman 903 and FTA filter papers, compared to the gold standard of culture.

Methods

Between September 2011 to May 2015, blood was collected from children 5 years of age or under who presented to six hospital study sites throughout northern and central Nigeria with febrile illness, and inoculated into blood culture bottles or spotted onto Whatman 903 or FTA filter paper. Culture and rt-PCR were performed on all samples.

Results

A total of 537 DBS specimens from 535 children were included in the study, of which 15 were culture-positive for S. pneumoniae. The rt-PCR assay detected S. pneumoniae in 12 DBS specimens (2.2%). One positive rt-PCR result was identified in a culture-negative specimen from a high-risk subject, and two positive rt-PCR results were negative on repeat testing. Six culture-confirmed cases of S. pneumoniae bacteremia were missed. Compared to culture, the overall sensitivities of Whatman 903 and FTA DBS for detection of S. pneumoniae were 57.1% (95% CI 18.4–90.1%) and 62.5% (95% CI 24.5–91.5%), respectively. Nonspecific amplification was noted in an additional 22 DBS (4.1%). Among these, six were positive for a non-S. pneumoniae pathogen on culture.

Conclusions

Rt-PCR was able to detect S. pneumoniae from clinical DBS specimens, including from a culture-negative specimen. Our findings show promise of this approach as a surveillance diagnostic, but also raise important cautionary questions. Several DBS specimens were detected as S. pneumoniae by rt-PCR despite growth of a non-S. pneumoniae pathogen on culture. A precise definition of what constitutes a positive result is required to avoid falsely over-identifying specimens.

The Relevance of a Novel Quantitative Assay to Detect up to 40 Major Streptococcus pneumoniae Serotypes Directly in Clinical Nasopharyngeal and Blood Specimens

For epidemiological and surveillance purposes, it is relevant to monitor the distribution and dynamics of Streptococcus pneumoniae serotypes. Conventional serotyping methods do not provide rapid or quantitative information on serotype loads. Quantitative serotyping may enable prediction of the invasiveness of a specific serotype compared to other serotypes carried. Here, we describe a novel, rapid multiplex real-time PCR assay for identification and quantification of the 40 most prevalent pneumococcal serotypes and the assay impacts in pneumonia specimens from emerging and developing countries. Eleven multiplex PCR to detect 40 serotypes or serogroups were optimized. Quantification was enabled by reference to standard dilutions of known bacterial load. Performance of the assay was evaluated to specifically type and quantify S. pneumoniae in nasopharyngeal and blood samples from adult and pediatric patients hospitalized with pneumonia (n = 664) from five different countries. Serogroup 6 was widely represented in nasopharyngeal specimens from all five cohorts. The most frequent serotypes in the French, South African, and Brazilian cohorts were 1 and 7A/F, 3 and 19F, and 14, respectively. When both samples were available, the serotype in blood was always present as carriage with other serotypes in the nasopharynx. Moreover, the ability of a serotype to invade the bloodstream may be linked to its nasopharyngeal load. The mean nasopharyngeal concentration of the serotypes that moved to the blood was 3 log-fold higher than the ones only found in the nasopharynx. This novel, rapid, quantitative assay may potentially predict some of the S. pneumoniae serotypes invasiveness and assessment of pneumococcal serotype distribution.

Alternative Pathway Inhibition by Exogenous Factor H Fails to Attenuate Inflammation and Vascular Leakage in Experimental Pneumococcal Sepsis in Mice

Streptococcus pneumoniae is a common cause of sepsis. Effective complement activation is an important component of host defence against invading pathogens, whilst excessive complement activation has been associated with endothelial dysfunction and organ damage. The alternative pathway amplification loop is important for the enhancement of complement activation. Factor H is a key negative regulator of the alternative pathway amplification loop and contributes to tight control of complement activation. We assessed the effect of inhibition of the alternative pathway on sepsis associated inflammation and disease severity using human factor H treatment in a clinically relevant mice model of pneumococcal sepsis. Mice were infected intravenously with live Streptococcus pneumoniae. At the first clinical signs of infection, 17 hours post-infection, mice were treated with ceftriaxone antibiotic. At the same time purified human factor H or in controls PBS was administered. Treatment with human factor H did not attenuate disease scores, serum pro-inflammatory cytokines, or vascular permeability and did not significantly affect C3 and C3a production at 26 h post-infection. Therefore, we conclude that inhibition of the alternative complement pathway by exogenous human factor H fails to attenuate inflammation and vascular leakage at a clinically relevant intervention time point in pneumococcal sepsis in mice.

Host Factors and Biomarkers Associated with Poor Outcomes in Adults with Invasive Pneumococcal Disease

BACKGROUND

Invasive pneumococcal disease (IPD) causes considerable morbidity and mortality. We aimed to identify host factors and biomarkers associated with poor outcomes in adult patients with IPD in Japan, which has a rapidly-aging population.

METHODS

In a large-scale surveillance study of 506 Japanese adults with IPD, we investigated the role of host factors, disease severity, biomarkers based on clinical laboratory data, treatment regimens, and bacterial factors on 28-day mortality.

RESULTS

Overall mortality was 24.1%, and the mortality rate increased from 10.0% in patients aged ˂50 years to 33.1% in patients aged ≥80 years. Disease severity also increased 28-day mortality, from 12.5% among patients with bacteraemia without sepsis to 35.0% in patients with severe sepsis and 56.9% with septic shock. The death rate within 48 hours after admission was high at 54.9%. Risk factors for mortality identified by multivariate analysis were as follows: white blood cell (WBC) count <4000 cells/μL (odds ratio [OR], 6.9; 95% confidence interval [CI], 3.7-12.8, p < .001); age ≥80 years (OR, 6.5; 95% CI, 2.0-21.6, p = .002); serum creatinine ≥2.0 mg/dL (OR, 4.5; 95% CI, 2.5-8.1, p < .001); underlying liver disease (OR, 3.5; 95% CI, 1.6-7.8, p = .002); mechanical ventilation (OR, 3.0; 95% CI, 1.7-5.6, p < .001); and lactate dehydrogenase ≥300 IU/L (OR, 2.4; 95% CI, 1.4-4.0, p = .001). Pneumococcal serotype and drug resistance were not associated with poor outcomes.

CONCLUSIONS

Host factors, disease severity, and biomarkers, especially WBC counts and serum creatinine, were more important determinants of mortality than bacterial factors.

Use of Blood Smears and Dried Blood Spots for Polymerase Chain Reaction-Based Detection and Quantification of Bacterial Infection and Plasmodium falciparum in Severely Ill Febrile African Children

Molecular approaches offer a means of testing archived samples stored as dried blood spots in settings where standard blood cultures are not possible. Peripheral blood films are one suggested source of material, although the sensitivity of this approach has not been well defined. Thin blood smears and dried blood spots from a severe pediatric malaria study were assessed using specific polymerase chain reaction (PCR) primers to detect non-typhoidal Salmonella (NTS; MisL gene), Streptococcus pneumoniae (lytA), and Plasmodium falciparum (18S rRNA). Of 16 cases of NTS and S. pneumoniae confirmed on blood culture, none were positive by PCR using DNA extracts from blood films or dried blood spots. In contrast, four of 36 dried blood spots and two of 178 plasma samples were PCR positive for S. pneumoniae, despite negative bacterial blood cultures, suggesting false positives. Quantitative assessment revealed that the effective concentration of P. falciparum DNA in blood films was three log orders of magnitude lower than for dried blood spots. The P. falciparum kelch13 gene could not be amplified from blood films. These findings question the value of blood PCR-based approaches for detection of NTS and S. pneumoniae, and show that stored blood films are an inefficient method of studying P. falciparum.

Minimum incidence of adult invasive pneumococcal disease in Blantyre, Malawi an urban african setting: a hospital based prospective cohort study

Invasive pneumococcal disease causes substantial morbidity and mortality in Africa. Evaluating population level indirect impact on adult disease of pneumococcal conjugate vaccine (PCV) programmes in infants requires baseline population incidence rates but these are often lacking in areas with limited disease surveillance. We used hospital based blood culture and cerebrospinal fluid surveillance to calculate minimal incidence of invasive pneumococcal disease in the adult (≥15 years old) population of Blantyre, a rapidly growing urban centre in southern Malawi, in the period preceding vaccine introduction. Invasive pneumococcal disease incidence in Blantyre district was high, mean 58.1 (95% confidence interval (CI): 53.7, 62.7) per 100,000 person years and peaking among 35 to 40 year olds at 108.8 (95%CI: 89.0, 131.7) mirroring the population age prevalence of HIV infection. For pneumococcal bacteraemia in urban Blantyre, mean incidence was 60.6 (95% CI: 55.2, 66.5) per 100,000 person years, peaking among 35 to 40 year olds at 114.8 (95%CI: 90.3, 143.9). We suspected that our surveillance may under-ascertain the true burden of disease, so we used location data from bacteraemic subjects and projected population estimates to calculate local sub-district incidence, then examined the impact of community level socio-demographic covariates as possible predictors of local sub-district incidence of pneumococcal and non-pneumococcal pathogenic bacteraemia. Geographic heterogeneity in incidence was marked with localised hotspots but ward level covariates apart from prison were not associated with pneumococcal bacteraemia incidence. Modelling suggests that the current sentinel surveillance system under-ascertains the true burden of disease. We outline a number of challenges to surveillance for pneumococcal disease in our low-resource setting. Subsequent surveillance in the vaccine era will have to account for geographic heterogeneity when evaluating population level indirect impact of PCV13 introduction to the childhood immunisation program.

Recurrent invasive pneumococcal disease in children: underlying clinical conditions, and immunological and microbiological characteristics

Purpose

Clinical, immunological and microbiological characteristics of recurrent invasive pneumococcal disease (IPD) in children were evaluated, differentiating relapse from reinfection, in order to identify specific risk factors for both conditions.

Methods

All patients <18 years-old with recurrent IPD admitted to a tertiary-care pediatric center from January 2004 to December 2011 were evaluated. An episode of IPD was defined as the presence of clinical findings of infection together with isolation and/or pneumococcal DNA detection by Real-Time PCR in any sterile body fluid. Recurrent IPD was defined as 2 or more episodes in the same individual at least 1 month apart. Among recurrent IPD, we differentiated relapse (same pneumococcal isolate) from reinfection.

Results

593 patients were diagnosed with IPD and 10 patients died. Among survivors, 23 episodes of recurrent IPD were identified in 10 patients (1.7%). Meningitis was the most frequent form of recurrent IPD (10 episodes/4 children) followed by recurrent empyema (8 episodes/4 children). Three patients with recurrent empyema caused by the same pneumococcal clone ST306 were considered relapses and showed high bacterial load in their first episode. In contrast, all other episodes of recurrent IPD were considered reinfections. Overall, the rate of relapse of IPD was 0.5% and the rate of reinfection 1.2%. Five out of 7 patients with reinfection had an underlying risk factor: cerebrospinal fluid leak (n = 3), chemotherapy treatment (n = 1) and a homozygous mutation in MyD88 gene (n = 1). No predisposing risk factors were found in the remainder.

Conclusions

recurrent IPD in children is a rare condition associated with an identifiable risk factor in case of reinfection in almost 80% of cases. In contrast, recurrent IPD with pleuropneumonia is usually a relapse of infection.

Antibody and plasmablast response to 13-valent pneumococcal conjugate vaccine in chronic lymphocytic leukemia patients--preliminary report

BACKGROUND

Chronic lymphocytic leukemia (CLL) leads to significant immune system dysfunction. The predominant clinical presentation in 50% of patients involves recurrent, often severe, infections. Infections are also the most common (60-80%) cause of deaths in CLL patients. The scope of infections varies with the clinical stage of the disease. Treatment-naive patients typically present with respiratory tract infections caused by encapsulated bacteria Streptococcus pneumoniae and Haemophilus influenzae. Since 2012, the 13-valent pneumococcal conjugate vaccine (PCV13) has been recommended in the United States and some EU countries for pneumococcal infection prevention in patients with CLL (besides the long-standing standard, 23-valent pneumococcal polysaccharide vaccine, PPV23). The aim of this study was to compare the immune response to PCV13 in 24 previously untreated CLL patients and healthy subjects.

METHODS

Both groups were evaluated for: the levels of specific pneumococcal antibodies, the levels of IgG and IgG subclasses and selected peripheral blood lymphocyte subpopulations including the frequency of plasmablasts before and after immunization.

RESULTS

Adequate response to vaccination, defined as an at least two-fold increase in specific pneumococcal antibody titers versus pre-vaccination baseline titers, was found in 58.3% of CLL patients and 100% of healthy subjects. Both the CLL group and the control group demonstrated a statistically significant increase in the IgG2 subclass levels following vaccination (P = 0.0301). After vaccination, the frequency of plasmablasts was significantly lower (P<0.0001) in CLL patients in comparison to that in controls. Patients who responded to vaccination had lower clinical stage of CLL as well as higher total IgG, and IgG2 subclass levels. No significant vaccine-related side effects were observed.

CONCLUSIONS

PCV13 vaccination in CLL patients is safe and induces an effective immune response in a considerable proportion of patients. To achieve an optimal vaccination response, the administration of PCV13 is recommended as soon as possible following CLL diagnosis.

Dietary supplementation with Lactobacilli improves emergency granulopoiesis in protein-malnourished mice and enhances respiratory innate immune response

This work studied the effect of protein malnutrition on the hemato-immune response to the respiratory challenge with Streptococcus pneumoniae and evaluated whether the dietary recovery with a probiotic strain has a beneficial effect in that response. Three important conclusions can be inferred from the results presented in this work: a) protein-malnutrition significantly impairs the emergency myelopoiesis induced by the generation of the innate immune response against pneumococcal infection; b) repletion of malnourished mice with treatments including nasally or orally administered Lactobacillus rhamnosus CRL1505 are able to significantly accelerate the recovery of granulopoiesis and improve innate immunity and; c) the immunological mechanisms involved in the protective effect of immunobiotics vary according to the route of administration. The study demonstrated that dietary recovery of malnourished mice with oral or nasal administration of L. rhamnosus CRL1505 improves emergency granulopoiesis and that CXCR4/CXCR12 signaling would be involved in this effect. Then, the results summarized here are a starting point for future research and open up broad prospects for future applications of probiotics in the recovery of immunocompromised malnourished hosts.

Toll-like receptor 4 stimulation before or after Streptococcus pneumoniae induced sepsis improves survival and is dependent on T-cells

Introduction

Endotoxin tolerance improves outcomes from gram negative sepsis but the underlying mechanism is not known. We determined if endotoxin tolerance before or after pneumococcal sepsis improved survival and the role of lymphocytes in this protection.

Methods

Mice received lipopolysaccharide (LPS) or vehicle before or after a lethal dose of Streptococcus pneumoniae. Survival, quantitative bacteriology, liver function, and cytokine concentrations were measured. We confirmed the necessity of Toll-like receptor 4 (TLR4) for endotoxin tolerance using C3H/HeN (TLR4 replete) and C3H/HeJ (TLR4 deficient) mice. The role of complement was investigated through A/J mice deficient in C5 complement. CBA/CaHN-Btk^xid//J mice with dysfunctional B cells and Rag-1 knockout (KO) mice deficient in T and B cells delineated the role of lymphocytes.

Results

Endotoxin tolerance improved survival from pneumococcal sepsis in mice with TLR4 that received LPS pretreatment or posttreatment. Survival was associated with reduced bacterial burden and serum cytokine concentrations. Death was associated with abnormal liver function and blood glucose concentrations. Endotoxin tolerance improved survival in A/J and CBA/CaHN-Btk^xid//J mice but not Rag-1 KO mice.

Conclusions

TLR4 stimulation before or after S. pneumoniae infection improved survival and was dependent on T-cells but did not require an intact complement cascade or functional B cells.

Immunogenicity, impact on carriage and reactogenicity of 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine in Kenyan children aged 1-4 years: a randomized controlled trial

Background

The impact on carriage and optimal schedule for primary vaccination of older children with 10-valent pneumococcal non-typeable Haemophilus influenzae protein-D conjugate vaccine (PHiD-CV) are unknown.

Methods

600 Kenyan children aged 12–59 months were vaccinated at days 0, 60 and 180 in a double-blind randomized controlled trial according to the following vaccine sequence: Group A: PHiD-CV, PHiD-CV, diphtheria/tetanus/acellular pertussis vaccine (DTaP); Group B: PHiD-CV, DTaP, PHiD-CV; Group C: hepatitis A vaccine (HAV), DTaP, HAV. Nasopharyngeal carriage of Streptococcus pneumoniae was measured at five timepoints. In 375 subjects, serotype-specific responses were measured by 22F-inhibition ELISA and opsonophagocytic killing assays (OPA) one month after vaccination.

Results

Following one dose of PHiD-CV, >90% of recipients developed IgG≥0.35 µg/mL to serotypes 1, 4, 5, 7F, 9V and 18C and OPA≥8 to serotypes 4, 7F, 9V, 18C, 23F. After a second dose >90% of recipients had IgG≥0.35 µg/mL to all vaccine serotypes and OPA≥8 to all vaccine serotypes except 1 and 6B. At day 180, carriage of vaccine-type pneumococci was 21% in recipients of two doses of PHiD-CV (Group A) compared to 31% in controls (p = 0.04). Fever after dose 1 was reported by 41% of PHiD-CV recipients compared to 26% of HAV recipients (p<0.001). Other local and systemic adverse experiences were similar between groups.

Conclusions

Vaccination of children aged 12–59 months with two doses of PHiD-CV two to six months apart was immunogenic, reduced vaccine-type pneumococcal carriage and was well-tolerated. Administration of PHiD-CV would be expected to provide effective protection against vaccine-type disease.

Trial Registration

ClinicalTrials.gov NCT01028326

[Clinical characteristics of children with Streptococcus pneumoniae septicemia and drug sensitivity of Streptococcus pneumoniae]

OBJECTIVE

To study the clinical characteristics of children who suffered from Streptococcus pneumoniae (SP) septicemia and the drug sensitivity of SP strains.

METHODS

A retrospective analysis was performed on the clinical data of 25 children with SP septicemia between January 2009 and December 2012.

RESULTS

Of the 25 cases, 16 (64%) were aged under 2 years, 5 (20%) were aged 2-5 years, and 4 (16%) were aged over 5 years. Fourteen cases (56%) were complicated by infection of other organs, and 5 cases (20%) had underlying chronic diseases. Fever was the most common clinical manifestation, and the majority presented with remittent fever. Eight patients with pneumonia or pyothorax had pulmonary symptoms. Five patients with purulent meningitis had neurological symptoms, five cases had hepatosplenomegaly and two cases had septic shock. Nineteen cases (76%, 19/25) had significantly elevated white blood cell (WBC) counts, twenty-one cases (84%, 21/25) had significantly elevated serum C-reactive protein (CRP) levels, and eight cases (50%, 8/16) had significantly elevated serum procalcitonin (PCT) levels. The drug sensitivity analysis showed that invasive SP had high resistance rates to penicillin (96%), clindamycin hydrochloride (88%) and erythromycin (84%), and it was completely sensitive to imipenem, vancomycin, levofloxacin and linezolid. The multi-drug resistance rate of invasive SP was up to 88%. Twenty-three cases (92%) were cured or improved after active treatment.

CONCLUSIONS

SP septicemia is commonly seen in children aged under 2 years. The most common clinical manifestation is fever, accompanied by elevated WBC count, CRP level and PCT level, and it is usually complicated by pulmonary or brain infection. Resistance to multiple antibiotics is very common in SP strains, so it is important to properly use antibiotics according to drug sensitivity test results. Patients who receive active treatment have a good clinical outcome.

[Experience of application of pneumococcus vaccines for studies of humoral immunity]

AIM

Evaluate possible use of Pneumo-23 pneumococcus polysaccharide vaccine and Prevenar-7 conjugated vaccine in EIA as antigens for determination of IgG levels against capsule polysaccharides.

MATERIALS AND METHODS

Solid phase EIA method with sorption on polystyrol of commercial vaccines Penumo-23 and Prevenar-7 was used in the study. Blood sera of 41 children before immunization and sera of 8 children before and after vaccination with Pneumo-23 and Prevenar-7 were analyzed. IgG level was determined in standard units (u.).

RESULTS

Mean level of antibodies in groups of unimmunized children against antigens of both vaccines were in the range of 52.3-69.1 u. (p > 0.05). The number of children with diagnostically significant level of antibodies (114 - 120 u.) was 2.4% in the control group (1/41) when Pneumo-23 antigens were used and 7.3% (3/41) when Prevenar-7 antigens were used. After vaccination with Pneumo-23 the fraction of diagnostically significant level of antibodies against Pneumo-23 antigens was on average higher by 1.8 times than in pre-vaccination period in 62.5% of children, and against Prevenar-7 antigens - by 1.6 times higher in 75% of children. After immunization with Prevenar-7 vaccine the level of antibodies increased by 3-4 times against antigens of both vaccines and reached diagnostically significant in 100% of cases.

CONCLUSION

Pneumo-23 and Prevenar-7 pneumococcal vaccines may be used as antigens for determination of antibodies against capsule polysaccharides of Streptococcus pneumoniae in EIA. Higher sensitivity of EIA based on Prevenar-7 allows to recommend this test for studies of postvaccination immunity in immunized with both conjugated and non-conjugated polysaccharide pneumococcal vaccines.

Role of an iron-dependent transcriptional regulator in the pathogenesis and host response to infection with Streptococcus pneumoniae

Iron is a critical cofactor for many enzymes and is known to regulate gene expression in many bacterial pathogens. Streptococcus pneumoniae normally inhabits the upper respiratory mucosa but can also invade and replicate in lungs and blood. These anatomic sites vary considerably in both the quantity and form of available iron. The genome of serotype 4 pneumococcal strain TIGR4 encodes a putative iron-dependent transcriptional regulator (IDTR). A mutant deleted at idtr (Δidtr) exhibited growth kinetics similar to parent strain TIGR4 in vitro and in mouse blood for up to 48 hours following infection. However, Δidtr was significantly attenuated in a murine model of sepsis. IDTR down-regulates the expression of ten characterized and putative virulence genes in nasopharyngeal colonization and pneumonia. The host cytokine response was significantly suppressed in sepsis with Δidtr. Since an exaggerated inflammatory response is associated with a poor prognosis in sepsis, the decreased inflammatory response could explain the increased survival with Δidtr. Our results suggest that IDTR, which is dispensable for pneumococcal growth in vitro, is associated with regulation of pneumococcal virulence in specific host environments. Additionally, IDTR ultimately modulates the host cytokine response and systemic inflammation that contributes to morbidity and mortality of invasive pneumococcal disease.

[Pneumococcal bacteremia in adult patients at a hospital in Madrid: serotypes and susceptibility]

INTRODUCTION

The aim of this study is to describe the distribution of Streptococcus pneumoniae serotypes, its antimicrobial susceptibility profiles and the relation with vaccines in pneumococcal invasive strains isolated from blood cultures of adult patients.

METHODS

All pneumococci isolated (67 strains) from blood cultures were serotyped by latex agglutination (Pneumotest latex) and Quellung reaction (Statens Serum Institut, Denmark). Antimicrobial susceptibility testing to penicillin (PEN), cefotaxime (CT), erythromycin (ERY) and levofloxacin (LEV) was performed by the E-test method (Biomèrieux, France).

RESULTS

Among the 67 strains isolated, the most prevalent serotypes were 22F (11.9%) and 3 (11.9%), the second most frequent were 7F (7.5%) and 19A (7.5%). The coverage of the strains by the pneumococcal 7-valent conjugate vaccine (VNC7V), pneumococcal 13-valent conjugate vaccine (VNC13V) and pneumococcal 23-valent polysaccharide (VNP23V) were 16, 49 and 82%, respectively. Serotypes 22F and 3 were responsible for 14 of the 48 episodes of pneumonia with bacteremia (29.2%) and only 2 of the 19 episodes (10.5%) of bacteremia without pneumonia. According to the 2007 CLSI criteria, 12 strains (17.9%) were non-susceptible to penicillin. Eleven of this 12 strains (91.7%) were resistant to erythromycin, simultaneously.

CONCLUSIONS

The most common serotypes were 22F, 3, 7F y 19A. Three of them (3, 7F y 19A) are serotypes that are covered by the new VNC13V but not by VNC7V. Serotype 22F is a serotype emergent that is not covered by the VNC7V. The percentage of non-susceptibility to penicillin and resistance to erythromycin was comparable to the percentage reported in our country.

Invasive pneumococcal disease among hospitalized children aged 28 days to 60 months in Jarkarta

Streptococcus pneumoniae is a leading cause of morbidity and mortality among children worldwide. Prevention of invasive pneumococcal disease (IPD) with a pneumococcal conjugate vaccine (PCV) is an effective approach to reduce the burden of pneumococcal disease. Nationwide epidemiological data is required prior to considering universal pneumococcal immunization for Indonesia. This preliminary study aimed to quantify the burden of IPD among hospitalized children at Cipto Mangunkusumo Hospital and Fatmawati Hospital, Jakarta. We studied 205 subjects aged 28 days to 60 months who were admitted with the diagnosis of pneumonia, meningitis, sepsis, and suspected occult bacteremia. Streptococcus pneumoniae was isolated from 1 of 205 blood specimens, giving an IPD proportion of 0.5%. The IPD case in this study was a 3-month-old baby with meningitis and bilateral lobar pneumonia. The Quellung test demonstrated serotype 7F. The isolate was susceptible to amoxicillin and Cotrimoxazole. Incidence of IPD could not be calculated due to low number of cases; this underscores the importance of surveillance of pneumococcal disease in Indonesia.

Vaccination-induced changes in human B-cell repertoire and pneumococcal IgM and IgA antibody at different ages

It is well known that older people are more susceptible to morbidity and mortality from infectious diseases, particularly from pulmonary diseases such as pneumococcal pneumonia where vaccines do not provide efficient protection as in younger populations. We have previously shown that the B-cell repertoire in the old is reduced and hypothesise that this may contribute to the impaired humoral responses of the elderly. Here, we investigated the repertoire and antibody responses to winter vaccination in two age groups, aged 18-49 and 65-89. We found that the serum IgM and IgA pneumococcal responses were significantly impaired in the older group, with no difference in IgG levels. IGHM spectratype analysis seems to be the most promising in terms of its predictive ability for vaccine responses. Spectratypes showed a clear change in the repertoire at day 7 after vaccination, with a return to the baseline levels at day 28. The changes at day 7 reflected expansion of IGH sequences that have smaller, more hydrophilic, CDR3 regions, and these changes were attenuated in the older group. The older group was more likely to have spectratypes indicative of a reduced diversity at day 0 and day 28. On average, the baseline repertoire in the older group was comprised of larger CDR3 regions than in the younger group. In conclusion, IgA and IgM responses are significantly impaired in the elderly pneumococcal response and are likely key mediators of protection. Hydrophilicity and/or small size of the IGH CDR3 appear to be important in these responses.

Ten years of surveillance for invasive Streptococcus pneumoniae during the era of antiretroviral scale-up and cotrimoxazole prophylaxis in Malawi

Objective

To document trends in invasive pneumococcal disease (IPD) in a central hospital in Malawi during the period of national scale-up of antiretroviral therapy (ART) and cotrimoxazole prophylaxis.

Methods

Between 1 January 2000 and 31 December 2009 almost 100,000 blood cultures and 40,000 cerebrospinal fluid (CSF) cultures were obtained from adults and children admitted to the Queen Elizabeth Central Hospital, Blantyre, Malawi with suspected severe bacterial infection.

Results

4,445 pneumococcal isolates were obtained over the 10 year period. 1,837 were from children: 885 (19.9%) from blood and 952 (21.4%) from CSF. 2,608 were from adults: 1,813 (40.8%) from blood and 795 (17.9%) from CSF. At the start of the surveillance period cotrimoxazole resistance was 73.8% and at the end was 92.6%. Multidrug resistance (MDR) was present in almost one third of isolates and was constant over time. Free ART was introduced in Malawi in 2004. From 2005 onwards there was a decline in invasive pneumococcal infections with a negative correlation between ART scale-up and the decline in IPD (Pearson's correlation r = −0.91; p<0.001).

Conclusion

During 2004–2009, national ART scale-up in Malawi was associated with a downward trend in IPD at QECH. The introduction of cotrimoxazole prophylaxis in HIV-infected groups has not coincided with a further increase in pneumococcal cotrimoxazole or multidrug resistance. These data highlight the importance of surveillance for high disease burden infections such as IPD in the region, which will be vital for monitoring pneumococcal conjugate vaccine introduction into national immunisation programmes.

[Analysis on pneumococcus isolated from part of china using serotype and pulsed-field gel electrophoresis]

OBJECTIVE

To investigate the serotype distribution and molecular features of Streptococcus pneumonia isolates in China.

METHODS

144 strains isolated from 6 provines were selected as the research object. The serotypes were determined with the method of capsular swelling. The molecular characteristics were conducted by optimized pulsed-field gel electrophoresis.

RESULTS

A total of 135 Streptococcus pneumoniae isolates were divided into 14 serogroups. 19, 6, 15, 23 serogroups are prevalent types in China. 9 isolates were failed to identify specific serogroups. All isolates could be divided into 92 pulsotypes. Pulsotypes were scattered. Absolutely dominant pulsotype was not found. Pulsotypes were similar among same serogroup isolates.

CONCLUSION

The pneumococcus of serogroup 19, 6, 15, 23 were common in China. PFGE had strong discriminatory ability of subtyping of Streptococcus pneumoniae. PFGE showed better epidemiological survey capacity.

Combination of pneumococcal surface protein A (PspA) with whole cell pertussis vaccine increases protection against pneumococcal challenge in mice

Streptococcus pneumoniae is the leading cause of respiratory acute infections around the world. In Latin America, approximately 20,000 children under 5 years of age die of pneumococcal diseases annually. Pneumococcal surface protein A (PspA) is among the best-characterized pneumococcal antigens that confer protection in animal models of pneumococcal infections and, as such, is a good alternative for the currently available conjugated vaccines. Efficient immune responses directed to PspA in animal models have already been described. Nevertheless, few low cost adjuvants for a subunit pneumococcal vaccine have been proposed to date. Here, we have tested the adjuvant properties of the whole cell Bordetella pertussis vaccine (wP) that is currently part of the DTP (diphtheria-tetanus-pertussis) vaccine administrated to children in several countries, as an adjuvant to PspA. Nasal immunization of BALB/c mice with a combination of PspA5 and wP or wP(low)--a new generation vaccine that contains low levels of B. pertussis LPS--conferred protection against a respiratory lethal challenge with S. pneumoniae. Both PspA5-wP and PspA5-wP(low) vaccines induced high levels of systemic and mucosal antibodies against PspA5, with similar profile, indicating no essential requirement for B. pertussis LPS in the adjuvant properties of wP. Accordingly, nasal immunization of C3H/HeJ mice with PspA5-wP conferred protection against the pneumococcal challenge, thus ruling out a role for TLR4 responses in the adjuvant activity and the protection mechanisms triggered by the vaccines. The high levels of anti-PspA5 antibodies correlated with increased cross-reactivity against PspAs from different clades and also reflected in cross-protection. In addition, passive immunization experiments indicated that antibodies played an important role in protection in this model. Finally, subcutaneous immunization with a combination of PspA5 with DTP(low) protected mice against challenge with two different pneumococcal strains, opening the possibility for the development of a combined infant vaccine composed of DTP and PspA.

Preparation and immunogenicity of capsular polysaccharide-surface adhesin A (PsaA) conjugate of Streptococcuspneumoniae

The efforts were focused on exploring alternative pneumococcal vaccine strategies, aimed at addressing the shortcomings of existing formulations, without compromising efficacy. We generated a stable Escherichia coli construct expressing functional recombinant PsaA and prepared CPS-rPsaA conjugate. The distribution of anti-CPS antibody response was almost completely of IgG2a subclass followed by IgG3 and low level of IgG1 subclass, which was opposite to the distribution of anti-PsaA IgG subclass antibodies. Though rPsaA was not detectable on the surface of the pneumococcal strain, the CPS-rPsaA conjugate possessed more accessibility to the surface of the strain. Mice immunized with conjugate exhibited rapid bacterial clearance from blood for the first 23h and afterward provided the best protection against challenge with pneumococcal 23F strain.

Organ-specific models of Streptococcus pneumoniae Disease

The variability of the course of infection by Streptococcus pneumoniae is well known but poorly understood. Most animal models of pneumonia, sepsis or meningitis have been forced to use site-specific bacterial inoculation to mimic localized human infection. This study examined the differences in the progression of disease-causing strains D39 (serotype 2), A66.1 (serotype 3) and TIGR4 (serotype 4) using isolates transformed with the Gram-positive lux transposon cassette, Tn4001 luxABCDE Km(r). Expression of the lux operon results in bioluminescence, permitting the detection of the bacteria within a living animal while using a CCD camera. Mice infected intranasally with A66.1 developed only pneumonia, those challenged with D39 experienced high-grade sepsis, while TIGR4 infection resulted in low-grade pneumonia and bacteremia ultimately progressing to meningitis. Quantitative analysis of bacterial titers confirmed these patterns, which were consistent across different lineages of mice. Mice anesthetized with ketamine and xylazine developed more severe forms of the disease compared with isoflurane. These studies unambiguously characterize 3 distinct models of the natural course of pneumococcal infection. Mapping these models provides a framework for detailed molecular modeling of pneumococcal virulence determinants at specific stages of disease.

Impaired bacterial clearance in type 3 deiodinase-deficient mice infected with Streptococcus pneumoniae

The activation of type 3 deiodinase (D3) has been postulated to play a role in the reduction of thyroid hormone levels during illness. Using a mouse model of acute bacterial infection, we have recently demonstrated marked D3 immunostaining in neutrophils infiltrating infected organs. These observations suggest a possible additional role for this enzyme in the innate immune response. To further assess the role of D3 in the response to acute bacterial infection, we used null D3 [D3 knockout (D3KO)] and wild type (WT) mice and infected them with Streptococcus pneumoniae. Marked reductions in serum thyroid hormone levels were observed both in D3KO and WT mice. Infection resulted also in a decrease in liver D1 activity in WT, but not in infected D3KO mice. Upon infection, pulmonary neutrophilic influx (measured by myeloperoxidase levels) and IL-6 and TNF concentrations increased equally in D3KO and WT mice, and histological examination of infected mice showed similar pulmonary inflammation in both strains. However, D3KO animals demonstrated significantly higher bacterial load in blood, lung, and spleen compared with WT mice. We conclude that 1) D3 is not required to generate the systemic manifestations of the nonthyroidal illness syndrome in this model; 2) the lack of D3 does not affect the extent of pulmonary inflammation; and 3) bacterial outgrowth in blood, spleen, and lung of D3KO mice is significantly higher than in WT mice. Our results suggest a protective role for D3 in the defense against acute bacterial infection, probably by reinforcing the microbial killing capacity of neutrophils.

[Assessment of effect of vaccination against pneumococcal infection in children with chronic renal failure and glomerulonephritis]

Clinical effect and immune response to vaccination with PNEUMO 23 vaccine was assessed in 18 children with chronic renal failure (CRF) and 40 children with different forms of glomerulonephritis (GN) aged 2 - 15 years. Control group was comprised by nonvaccinated patients (16 patients with CRF; 20 -with GN). Children from two groups were comparable on age and severity of disease's course. Local adverse reactions with duration not longer than 2 days were registered in 22% of vaccinees with CRF, and in 20% of vaccinees with GN. Mild and moderate systemic reactions were registered in 11% and 7.5% of recipients respectively. 1 month after vaccination significant 2.5 - 3.2-fold increase of antibodies concentration was detected in all groups irrespective from nosology and previous treatment. Two-fold increase of concentration of antibodies was observed in 64% and 61% of children with GN and CRF respectively. Clinical effect of vaccination appeared as 2.9-fold decrease of acute respiratory disease (ARD) incidence. Demand in antibacterial therapy decreased by 6.4-fold. Duration of ARD and course of antibacterial treatment decreased by 2.2 and 3 times respectively. Proportion of GN exacerbations related to infecvion decreased from 39% before vaccination to 8% after vaccination. In the control group this proportion did not change (50% and 45% respectively). Vaccine efficacy index was 2.13, coefficient of efficacy - 53.1%.

[Effect of vaccination against pneumococcal infection in children with type 1 diabetes mellitus]

Vaccination with polysaccharide pneumococcal vaccine "Pneumo 23" (Sanofi Pasteur, France) was performed in 31 children with type 1 diabetes mellitus (DM1) as well as in 19 children with respiratory tract diseases (asthma, chronic pneumonia), which formed comparison group. Fourty-three unvaccinated children with DM1 were included in the control group. Dynamics of IgG levels to mixture of pneumococcal polysaccharides (PS) included in the vaccine as well as to PS of serotypes 3, 6B, 9N, 23F, and to cell wall polysaccharides of Streptococcus pneumoniae were assessed. Using ELISA method, significant increase of IgG levels to mixture of PS and to PS of pneumococcal serotype 3 was detected. Although intensity of immune response to vaccination in children with respiratory diseases was significantly higher compared to children with DM1 (mean geometric titer of antibodies, proportion of patients with high antibody titers, and with 4-fold seroconversion). Development of methods to strengthen immune response in children with DM1 vaccinated against pneumococcal infection is required.

Successful downstream application of the Paxgene Blood RNA system from small blood samples in paediatric patients for quantitative PCR analysis

Background

The challenge of gene expression studies is to reliably quantify levels of transcripts, but this is hindered by a number of factors including sample availability, handling and storage. The PAXgene™ Blood RNA System includes a stabilizing additive in a plastic evacuated tube, but requires 2.5 mL blood, which makes routine implementation impractical for paediatric use.

The aim of this study was to modify the PAXgene™ Blood RNA System kit protocol for application to small, sick chidren, without compromising RNA integrity, and subsequently to perform quantitative analysis of ICAM and interleukin-6 gene expression.

Aliquots of 0.86 mL PAXgene™ reagent were put into microtubes and 0.3 mL whole blood added to maintain the same recommended proportions as in the PAXgene™ evacuated tube system. RNA quality was assessed using the Agilent BioAnalyser 2100 and an in-house TaqMan™ assay which measures GAPDH transcript integrity by determining 3' to 5' ratios. qPCR analysis was performed on an additional panel of 7 housekeeping genes. Three reference genes (HPRT1, YWHAZ and GAPDH) were identified using the GeNORM algorithm, which were subsequently used to normalising target gene expression levels. ICAM-1 and IL-6 gene expression were measured in 87 Malawian children with invasive pneumococcal disease.

Results

Total RNA yield was between 1,114 and 2,950 ng and the BioAnalyser 2100 demonstrated discernible 18s and 28s bands. The cycle threshold values obtained for the seven housekeeping genes were between 15 and 30 and showed good consistency. Median relative ICAM and IL-6 gene expression were significantly reduced in non-survivors compared to survivors (ICAM: 3.56 vs 4.41, p = 0.04, and IL-6: 2.16 vs 6.73, p = 0.02).

Conclusion

We have successfully modified the PAXgene™ blood collection system for use in small children and demonstrated preservation of RNA integrity and successful quantitative real-time PCR analysis.

WHO expert consultation on serotype composition of pneumococcal conjugate vaccines for use in resource-poor developing countries, 26–27 October 2006, Geneva

Pneumococcal conjugate vaccines induce serotype specific protection, with cross-protection seen between serotypes within certain serogroups. Though most serious pneumococcal infections are caused by relatively small number of serotypes, choices need to be made on the serotypes to be included in the vaccine because of the complexity and cost related to developing and producing vaccines with increasing number of serotypes. The choice is rendered difficult because of differences in the distribution of serotypes causing serious disease between different geographic regions and age groups as well as changes over time. The World Health Organization convened an expert consultation to formulate a data-driven approach to determine the minimum or optimal formulation of pneumococcal conjugate vaccines, particularly keeping in mind the needs of developing countries as well as the epidemiologic, regulatory, formulation and manufacturing issues involved. The deliberations and conclusions of this meeting are summarized in this report.

Chemokine responses are increased in HIV-infected Malawian children with invasive pneumococcal disease

BACKGROUND

Chemokines play an important role in the recruitment and regulation of leukocyte traffic during bacterial infection. The aims of this study were to investigate the chemokine response to invasive pneumococcal disease (IPD) and to examine the influence of HIV infection on the chemokine response, pneumococcal bacterial loads, and outcome.

METHODS

We prospectively studied 95 children with IPD, and blood and cerebrospinal fluid (CSF) samples were taken at admission for the determination of chemokines, interferon-gamma (IFNgamma), and pneumococcal bacterial loads.

RESULTS

Plasma CXCL8 and CCL2, CSF CXCL8 and CCL4, and IFNgamma were significantly higher in HIV-infected children than in HIV-uninfected children. Blood and CSF pneumococcal bacterial loads correlated with plasma and CSF chemokines, respectively, and were higher in HIV-infected children compared with HIV-uninfected children. Among HIV-infected children, plasma concentrations of CXCL8 and CCL2 were significantly higher in nonsurvivors than in survivors, but CCL5 was significantly lower. HIV-infected and HIV-uninfected children with IPD had higher concentrations of chemokines (except CCL5) than acutely ill HIV-infected and HIV-uninfected children with no detectable bacterial infection. Male gender and low plasma CCL2 concentrations were shown to be independently associated with survival.

CONCLUSIONS

Chemokines, in particular CCL2, are associated with survival in IPD and correlate with pneumococcal bacterial loads, disease presentation, and outcome.

Secondary alteration of the transferrin isoelectric focusing pattern in a case of bacterial meningitis

Congenital disorders of glycosylation (CDG) are a group of inherited defects in the synthesis and processing of the linked glycans of glycoproteins and other glycoconjugates. The phenotypic spectrum presents wide variability, and clinical diagnosis is not reliable in most cases. Isoelectric focusing (IEF) of serum transferrin is widely used as a tool to detect CDG. We describe a paediatric patient presenting an altered serum transferrin pattern due to a secondary disorder of glycosylation caused by pneumococcal meningitis (Streptococcus pneumoniae, serotype 19A). During admission, brain CT scan and MRI showed acute ischaemic lesions in brain frontotemporal parenchyma, and enlarged subarachnoidal spaces in the frontal area resembling a chronic injury. This led us to screen for inborn errors of metabolism potentially associated with these findings (homocystinuria, glutaric aciduria, CDG syndromes). Biochemical studies for the screening of these inborn errors of metabolism were normal except for sialotransferrin isoelectric focusing, which showed a type 2 pattern. However, 16 days later, together with the remission of the meningitis process, the sialotransferrin pattern had normalized. The apolipoprotein C-III (an O-glycoprotein) profile was normal in all samples analysed. In conclusion, infectious events should be ruled out in the differential diagnosis of CDG syndromes. Furthermore, our findings highlight the possibility that the type 2 IEF pattern of serum sialotransferrin detected in some patients with neonatal death due to organ failure and septic events might be secondary to the infectious process.

Prevention of pneumococcal infection in a patient with normal immunoglobulin levels but impaired polysaccharide antibody production

BACKGROUND

Patients with normal immunoglobulin levels may have an impaired response to immunization with pneumococcal vaccine and increased susceptibility to infection with encapsulated organisms. In children, but not adults, immunoglobulin replacement has been shown to be effective in reducing the infection rate.

OBJECTIVE

To reduce the incidence of infection in an adult with impaired response to pneumococcal vaccine but normal serum IgG levels.

METHODS

Intravenous IgG, 350 mg/kg, was given every 4 weeks.

RESULTS

The patient, who was hospitalized 3 times in 3 years with respiratory tract infections and who had documented infection with Streptococcus pneumoniae and Haemophilus influenzae, did not require antibiotic therapy for more than 15 months while undergoing intravenous immunoglobulin replacement therapy.

CONCLUSION

Adults with impaired response to vaccination with polyvalent pneumococcal vaccine and normal IgG levels may benefit from replacement therapy.

Overwhelming pneumococcal bacteremia revealed by a peripheral blood smear in a 74-year-old healthy woman

A 76-year-old woman, who had never been seriously ill, was admitted to our hospital with fever and shaking chills. She progressively developed septic shock. We detected Streptococcus pneumoniae in a routine examination of a Giemsa-stained peripheral blood smear. Despite intensive care with antibiotic therapy, she died within several hours after admission. A peripheral blood smear occasionally shows bacteria in cases of overwhelming septicemia, thus indicating a severe impairment of splenic function. We suggest that, in cases of severe septicemia, an examination of a peripheral blood smear is therefore useful for the rapid detection of organisms in comparison to a traditional blood culture.

[The drug susceptibility of penicillin-resistant Streptococcus pneumoniae]

The aim of our study was to evaluate a frequency of isolation and susceptibility to antibiotics of Streptococcus pneumoniae penicillin resistant among 154 strains S. pneumoniae isolated between 2003 and 2006 in University Hospital of Dr. A. Jurasza in Bydgoszcz. Antimicrobial susceptibility was assessed by disc-diffusion method according to the guidelines of Clinical and laboratory Standards Institute and The national Reference Centre for Antimicrobial Susceptibility. Minimal inhibitory concentrations for penicillin and cefotaxime were assessed by E-test method. Study shows increasing isolation of SPPR strains from 8,2% in 2003 to 32,0% in 2006. Strains were mostly isolated from patients ofNeurosurgery and Neurotraumatology Clinic and Rehabilitation Clinic. SPPR strains were mainly isolated from respiratory tract. Over 68% of SPPR showed intermediate resistance to penicillin and 73,3% of strains were susceptible to cefotaxime. Between 2003 and 2006 increased percentage of resistance strains to erythromycin, tetracycline and sulphometoxasol.

Differences in biofilm development and antibiotic susceptibility among Streptococcus pneumoniae isolates from cystic fibrosis samples and blood cultures

OBJECTIVES

To compare the capability of biofilm development between Streptococcus pneumoniae isolates from cystic fibrosis (CF) respiratory samples and those from non-CF blood cultures. Antibiotic susceptibility of biofilm-forming isolates, as well as differences between antibiotic susceptibility of sessile cells [minimum biofilm inhibitory concentration (MBIC)] and their planktonic counterparts (conventional MIC), were also assessed.

METHODS

Biofilm formation was performed using a microtitre method in 20 CF and 22 non-CF blood culture S. pneumoniae isolates.

RESULTS AND CONCLUSIONS

Biofilm formation occurs more frequently among S. pneumoniae isolates from CF (80%) than among non-CF blood culture isolates (50%) (P = 0.04). Moreover MBICs were significantly higher than conventional planktonic MICs among CF but not among non-CF blood isolates, suggesting a high adaptability of CF strains to form biofilms in adverse conditions.

Comparison of total white blood cell count and serum C-reactive protein levels in confirmed bacterial and viral infections

We report the association of reaction in inflammatory markers with the microbiologic etiology of infection in children. Total white blood cell counts were increased in most pneumococcal and Escherichia coli infections, but in less than one-half of Staphylococcus aureus infections. Adenoviruses were the only viral agents that often increased total white blood cell counts or serum C-reactive protein levels.

Macrophage serum markers in pneumococcal bacteremia: Prediction of survival by soluble CD163

OBJECTIVE

Soluble CD163 (sCD163) is a new macrophage-specific serum marker. This study investigated sCD163 and other markers of macrophage activation (neopterin, ferritin, transcobalamin, and soluble urokinase plasminogen activator receptor [suPAR]) as prognostic factors in patients with pneumococcal bacteremia.

DESIGN

Observational cohort study.

SETTING

Five university hospitals in Denmark.

PATIENTS

A total of 133 patients with Streptococcus pneumoniae bacteremia (positive blood culture) and 133 age- and gender-matched controls.

INTERVENTIONS

Samples were collected for biochemical analyses at the time of first positive blood culture.

MEASUREMENTS AND MAIN RESULTS

sCD163 was highly correlated with other macrophage markers and was significantly elevated (median [25-75 percentiles], 4.6 mg/L [2.8-8.9]) compared with healthy controls (2.7 mg/L [2.1-3.3], p < .0001). Increased levels were observed in patients who needed intensive care (hemodialysis, p = .0011; hypotension, p = .0014; mechanical ventilation, p = .0019). Significantly lower levels of sCD163, ferritin, transcobalamin, and suPAR (but not C-reactive protein) were measured in patients > or =75 yrs. In patients <75 yrs, all macrophage markers were increased in patients who died from their infection compared with survivors, whereas no change was observed in any of the markers in the very old age. At cutoff levels of 9.5 mg/L (sCD163) and 1650 nmol/L (C-reactive protein), the relative risk for fatal outcome in patients <75 yrs was 10.1 (95% confidence interval 3.4-31.0) and 7.0 (95% confidence interval 2.4-21.6) for sCD163 and C-reactive protein, respectively. In a multivariate logistic regression model for patients <75 yrs, ferritin, transcobalamin, neopterin, and suPAR contained no significant information on the probability of survival when sCD163 and CRP were known (p = .25).

CONCLUSIONS

Macrophage marker response in pneumococcal bacteremia was compromised in old age. In patients <75 yrs old, sCD163 was superior to other markers, including C-reactive protein, in predicting fatal disease outcome.