Epidemiology of Streptococcus pneumoniae-induced hemolytic uremic syndrome in Utah children

Emerging pneumococcal serotypes in Iraq: scope for improved vaccine development

Pneumococcal disease is a global public health concern as it affects the young, aged and the immunocompromised. The development of pneumococcal vaccines and their incorporation in the immunization programs has helped to reduce the global burden of disease. However, serotype replacement and the emergence of non-vaccine serotypes as well as the persistence of a few vaccine serotypes underscores the need for development of new and effective vaccines against such pneumococcal serotypes. In the Middle East, places of religious mass gatherings are a hotspot for disease transmission in addition to the global risk factors. Therefore, the periodic surveillance of pneumococcal serotypes circulating in the region to determine the effectiveness of existing prevention strategies and develop improved vaccines is warranted. Currently, there is a lack of serotype prevalence data for Iraq due to inadequate surveillance in the region. Thus, this review aims to determine the pneumococcal serotypes circulating in Iraq which may help in the development and introduction of improved pneumococcal vaccines in the country.

Streptococcus pneumoniae associated hemolytic uremic syndrome in children

Introduction

Previous small-scale, single-center investigations of Streptococcus pneumoniae associated hemolytic uremic syndrome (SpHUS) have shown increased disease severity among SpHUS relative to non-SpHUS patients. Our study compares the impact of S. pneumoniae on patient outcomes between SpHUS cases and non-SpHUS controls using the national, multicenter retrospective Pediatric Health Information Systems (PHIS) Database.

Methods

Children <18 years of age with a diagnosis of HUS were included. Univariate analyses and multivariable linear and logistic regressions were utilized to assess the impact of S. pneumoniae on mortality, length of stay (LOS), intensive care unit admission (ICU), and mechanical ventilation use. Models were adjusted for demographic and clinical characteristics, including cardiac, neurologic, pulmonary, gastrointestinal, immunologic and renal clinical complications.

Results

Of 3,952 index HUS hospitalizations, 231 (5.8%) were due to SpHUS. SpHUS patients had worse outcomes, including longer hospital stays, increased rate of ICU admission, and increased use of mechanical ventilation (p < 0.001 for all). There was a strong positive relationship between clinical complications and adverse outcomes. After adjusting for covariates, SpHUS was associated with an increase in hospital LOS by 3.47 days (p = 0.009) and overall ICU-LOS by 4.21 days (p < 0.001). SpHUS was also associated with increased likelihood of mechanical ventilation (OR: 3.08; p < 0.001), with no increase in ICU admission (p = 0.070) and in-hospital mortality (p = 0.3874).

Discussion

Our study highlights that SpHUS patients are at increased risk of multiple adverse outcomes likely due to the summative impact of pneumococcal infection and HUS as well as more frequent clinical complications.

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

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

Complement activation in children with Streptococcus pneumoniae associated hemolytic uremic syndrome

BACKGROUND

Hemolytic uremic syndrome caused by invasive pneumococcal disease (P-HUS) is rare in children and adolescents, but accompanied by high mortality in the acute phase and complicated by long-term renal sequelae. Abnormalities in the alternative complement pathway may additionally be contributing to the course of the disease but also to putative treatment options.

METHODS

Retrospective study to assess clinical course and laboratory data of the acute phase and outcome of children with P-HUS.

RESULTS

We report on seven children (median age 12 months, range 3-28 months) diagnosed with P-HUS. Primary organ manifestation was meningitis in four and pneumonia in three patients. All patients required dialysis which could be discontinued in five of them after a median of 25 days. In two patients, broad functional and genetic complement analysis was performed and revealed alternative pathway activation and risk haplotypes in both. Three patients were treated with the complement C5 inhibitor eculizumab. During a median follow-up time of 11.3 years, one patient died due to infectious complications after transplantation. Two patients showed no signs of renal sequelae.

CONCLUSIONS

Although pathophysiology in P-HUS remains as yet incompletely understood, disordered complement regulation seems to provide a clue to additional insights for pathology, diagnosis, and even targeted treatment.

New insights into the pathogenesis of Streptococcus pneumoniae-associated hemolytic uremic syndrome

The purpose of this review is to describe Streptococcus pneumoniae-associated hemolytic uremic syndrome (P-HUS) with emphasis on new insights into the pathophysiology and management over the past 10 years. Even though awareness of this clinico-pathological entity has increased, it likely remains under-recognized. Recent observations indicate that although neuraminidase activity and exposure of the T-antigen are necessary for development of P-HUS, they are not sufficient; activation of the alternate pathway of complement may also contribute. It is unclear, however, whether or not eculizumab and/or plasmapheresis are of value.

HEMOLYTIC UREMIC SYNDROME ASSOCIATED WITH STREPTOCOCCUS PNEUMONIAE IN PEDIATRICS: A CASE SERIES

Objective:

To describe a case series of four (4) patients with hemolytic uremic syndrome due to Streptococcus pneumoniae in a level four complexity institution in the city of Bogotá, D.C., Colombia.

Cases description:

We describe cases of four patients who presented respiratory symptoms and fever. All four patients were in regular conditions on hospital admission, after which they required intensive care and ventilatory support. Upon admission, three cases showed evidence of pleuropulmonary complication. Penicillin-sensitive Streptococcus pneumoniae was isolated in all cases. All patients presented anemia, severe thrombocytopenia, schistocytes on peripheral blood smear, and hyperazotemia. They required blood transfusion and renal replacement therapy during their hospitalization. The patients were diagnosed with hemolytic uremic syndrome due to S. pneumoniae. Three of the four patients had a progressive recovery of the renal function and were discharged after an average of 36 days of hospital stay. The remaining patient had two amputations in the extremities due to thrombotic vascular complications and was discharged after 99 days of hospital stay, requiring hemodialysis every other day.

Comments:

Hemolytic uremic syndrome due to Streptococcus pneumoniae is a rare but severe complication of invasive pneumococcal disease. Complicated pneumonia is the main condition associated with this entity. It is noteworthy the short period in which these cases were presented, considering the low annual incidence of the disease.

Pneumococcal-related Hemolytic Uremic Syndrome in the United Kingdom: National Surveillance, 2006-2016

BACKGROUND

children <5 years of age since the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in 2006 and its replacement with the 13-valent pneumococcal conjugate vaccine (PCV13) in 2010 in the United Kingdom.

METHODS

Public Health England conducts enhanced national surveillance of invasive pneumococcal disease in England. Confirmed invasive pneumococcal disease cases diagnosed between September 1, 2006, and March 31, 2016, with hemolytic uremic syndrome reported as a complication were included in the analysis.

RESULTS

There were 54 cases of pHUS during the surveillance period, with a median age of 17 months. The incidence of pHUS was 0.25/100,000 during the PCV7 period and 0.08/100,000 during the PCV13 period (incidence rate ratio: 0.31; 95% confidence interval: 0.16-0.57; P < 0.0001). Twelve children (22%) had an underlying comorbidity before disease onset. Overall, 31 (57%) presented with lower respiratory tract infection, 14 (25%) with meningitis, 8 (15%) with bacteremia and 1 (2%) with septic arthritis. An empyema was reported in 26/31 children (84%) with lower respiratory tract infection and cerebral abscess in 5/14 children (36%) with meningitis. The main responsible serotypes were 19A (n = 20), 3 (n = 6), 7F (n = 5) and 33F (n = 4). Eight children (15%) died, including 6 with meningitis.

CONCLUSIONS

pHUS continues to be associated with significant morbidity and mortality. The incidence of pHUS was significantly lower after PCV13 replaced PCV7 in the childhood immunization program. Currently, most cases are due to non-PCV13 serotypes.

Pneumococcal haemolytic uraemic syndrome in the postvaccine era

OBJECTIVE

Pneumococcal infection is a leading cause of haemolytic uraemic syndrome (HUS) and is potentially vaccine preventable. Published data suggest high mortality and poor renal outcomes. The introduction of the 7-valent pneumococcal conjugate vaccine (PCV) has seen the emergence of disease caused by non-vaccine strains, particularly 19A. We sought to describe serotype prevalence and outcomes, particularly after the introduction of the 13-valent PCV.

DESIGN AND SETTING

We performed a retrospective chart review, using hospital medical records to identify cases of HUS in a tertiary paediatric hospital in Australia over a 20-year period (January 1997-December 2016). Associated pneumococcal infection was identified, and serotype data were categorised according to vaccine era: prevaccine (January 1997-December 2004), PCV7 (January 2005-June 2011) and PCV13 (July 2011-December 2016).

RESULTS

We identified 66 cases of HUS. Pneumococcal infection was proven in 11 cases, representing 4% (1/26) of cases prior to the introduction of PCV7, 20% (3/15) in the PCV7 era and 28% (7/25) in the PCV13 era. Subtype 19A was the most prevalent pneumococcal serotype (6/11). All four patients who received PCV7 were infected with a non-vaccine serotype. Four of the five patients who received PCV13 were classed as vaccine failures. Median follow-up was 14 (range 1-108) months. Chronic kidney disease was the most common complication (4/7). We observed no mortality, neurological sequelae or progression to end-stage kidney disease.

CONCLUSIONS

Serotype 19A is most commonly associated with pneumococcal HUS, despite the introduction of the 13-valent vaccine. Chronic kidney disease is a significant complication of pneumococcal HUS.

ASC and NLRP3 impair host defense during lethal pneumonia caused by serotype 3 Streptococcus pneumoniae in mice

Streptococcus (S.) pneumoniae is the most common cause of community-acquired pneumonia. The Nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, consisting of NLRP3, ASC (the adaptor apoptosis-associated speck-like protein containing a CARD) and caspase-1, has been implicated in protective immunity during pneumonia induced by high doses of S. pneumoniae serotype 2. Here we investigated the role of the NLRP3 inflammasome in the host response during lethal airway infection with a low dose of serotype 3 S. pneumoniae. Mice were euthanized at predefined endpoints for analysis or observed in survival studies. In additional studies, Tlr2^-/- /Tlr4^-/- mice and Myd88^-/- mice incapable of Toll-like receptor signaling were studied. In stark contrast with existing literature, both Nlrp3^-/- and Asc^-/- mice showed a strongly improved host defense, as reflected by a markedly reduced mortality rate accompanied by diminished bacterial growth and dissemination. Host defense was unaltered in Tlr2^-/- /Tlr4^-/- mice and Myd88^-/- mice. These results show that the NLRP3 inflammasome impairs host defense during lethal pneumonia caused by serotype 3 S. pneumoniae. Our findings challenge the current paradigm that proximal innate detection systems are indispensable for an adequate host immune response against bacteria.

Pneumococcal Disease in the Era of Pneumococcal Conjugate Vaccine

Universal immunization of infants and toddlers with pneumococcal conjugate vaccines over the last 15 years has dramatically altered the landscape of pneumococcal disease. Decreases in invasive pneumococcal disease, all-cause pneumonia, empyema, mastoiditis, acute otitis media, and complicated otitis media have been reported from multiple countries in which universal immunization has been implemented. Children with comorbid conditions have higher rates of pneumococcal disease and increased case fatality rates compared with otherwise healthy children, and protection for the most vulnerable pediatric patients will require new strategies to address the underlying host susceptibility and the expanded spectrum of serotypes observed.

Defining the role of pneumococcal neuraminidases and O-glycosidase in pneumococcal haemolytic uraemic syndrome

The host and bacterial factors that lead to development of pneumococcal haemolytic uraemic syndrome (pHUS) remain poorly defined; however, it is widely believed that pneumococcal exposure of the Thomsen-Friedenreich antigen (T-antigen) on host surfaces is a key step in pathogenesis. Two enzymatic activities encoded by pneumococci determine the level of T-antigen exposed. Neuraminidases cleave terminal sialic acid to expose the T-antigen which is subsequently cleaved by O-glycosidase Eng. While a handful of studies have examined the role of neuraminidases in T-antigen exposure, no studies have addressed the potential role of O-glycosidase. This study used 29 pHUS isolates from the USA and 31 serotype-matched controls. All isolates contained eng, and no significant correlation between enzymatic activity and disease state (pHUS and blood non-pHUS isolates) was observed. A prior study from Taiwan suggested that neuraminidase NanC contributes to the development of pHUS. However, we observed no difference in nanC distribution. Similar to previously published data, we found no significant correlation between neuraminidase activity and disease state. Accurate quantification of these enzymatic activities from bacteria grown in whole blood is currently impossible, but we confirmed that there were no significant correlations between disease state and neuraminidase and O-glycosidase transcript levels after incubation in blood. Genomic sequencing of six pHUS isolates did not identify any genetic elements possibly contributing to haemolytic uraemic syndrome. These findings support the hypothesis that while exposure of T-antigen may be an important step in disease pathogenesis, host factors likely play a substantial role in determining which individuals develop haemolytic uraemic syndrome after pneumococcal invasive disease.

Postinfectious Hemolytic Uremic Syndrome

Post-infectious hemolytic uremic syndrome (HUS) is caused by specific pathogens in patients with no identifiable HUS-associated genetic mutation or autoantibody. The majority of episodes is due to infections by Shiga toxin (Stx) producing Escherichia coli (STEC). This chapter reviews the epidemiology and pathogenesis of STEC-HUS, including bacterial-derived factors and host responses. STEC disease is characterized by hematological (microangiopathic hemolytic anemia), renal (acute kidney injury) and extrarenal organ involvement. Clinicians should always strive for an etiological diagnosis through the microbiological or molecular identification of Stx-producing bacteria and Stx or, if negative, serological assays. Treatment of STEC-HUS is supportive; more investigations are needed to evaluate the efficacy of putative preventive and therapeutic measures, such as non-phage-inducing antibiotics, volume expansion and anti-complement agents. The outcome of STEC-HUS is generally favorable, but chronic kidney disease, permanent extrarenal, mainly cerebral complication and death (in less than 5 %) occur and long-term follow-up is recommended. The remainder of this chapter highlights rarer forms of (post-infectious) HUS due to S. dysenteriae, S. pneumoniae, influenza A and HIV and discusses potential interactions between these pathogens and the complement system.

Pneumococcal hemolytic uremic syndrome and steroid resistant nephrotic syndrome

Pneumococcal-associated hemolytic uremic syndrome (pHUS) is a rare but severe complication of invasive Streptococcus pneumoniae infection. We report the case of a 12-year-old female with steroid-resistant nephrotic syndrome treated with adrenocorticotrophic hormone (H.P. Acthar(®) Gel), who developed pneumococcal pneumonia and subsequent pHUS. While nephrotic syndrome is a well-known risk factor for invasive pneumococcal disease, this is the first reported case of pHUS in an adolescent patient with nephrotic syndrome, and reveals novel challenges in the diagnosis, treatment and potential prevention of this complication.

Role of Nucleotide-Binding Oligomerization Domain-Containing (NOD) 2 in Host Defense during Pneumococcal Pneumonia

Streptococcus (S.) pneumoniae is the most common causative pathogen in community-acquired pneumonia. Nucleotide-binding oligomerization domain-containing (NOD) 2 is a pattern recognition receptor located in the cytosol of myeloid cells that is able to detect peptidoglycan fragments of S. pneumoniae. We here aimed to investigate the role of NOD2 in the host response during pneumococcal pneumonia. Phagocytosis of S. pneumoniae was studied in NOD2 deficient (Nod2-/-) and wild-type (Wt) alveolar macrophages and neutrophils in vitro. In subsequent in vivo experiments Nod2-/- and Wt mice were inoculated with serotype 2 S. pneumoniae (D39), an isogenic capsule locus deletion mutant (D39Δcps) or serotype 3 S. pneumoniae (6303) via the airways, and bacterial growth and dissemination and the lung inflammatory response were evaluated. Nod2-/- alveolar macrophages and blood neutrophils displayed a reduced capacity to internalize pneumococci in vitro. During pneumonia caused by S. pneumoniae D39 Nod2-/- mice were indistinguishable from Wt mice with regard to bacterial loads in lungs and distant organs, lung pathology and neutrophil recruitment. While Nod2-/- and Wt mice also had similar bacterial loads after infection with the more virulent S. pneumoniae 6303 strain, Nod2-/- mice displayed a reduced bacterial clearance of the normally avirulent unencapsulated D39Δcps strain. These results suggest that NOD2 does not contribute to host defense during pneumococcal pneumonia and that the pneumococcal capsule impairs recognition of S. pneumoniae by NOD2.

Association of serotype with respiratory presentations of pneumococcal infection, Ontario, Canada, 2003-2011

BACKGROUND

Pneumococcal disease burden is difficult to quantify due to limited data regarding non-bacteremic disease. We assessed serotype-specific differences in pneumococcal disease presentations in adults in Toronto, Canada.

METHODS

From 2003 to 2011, population-based surveillance for invasive pneumococcal disease was conducted and respiratory pneumococcal isolates collected in Metropolitan Toronto/Peel Region, Canada. Episodes of care were classified into disease categories.

RESULTS

Of 3105 eligible cases of IPD, 2060 cases were bacteremic pneumonia, and 1045 bacteremia without pneumonia. Of 2751 eligible respiratory cases, 1542 (56.0%) were non-bacteremic pneumonia (NBPP), 467 (17.0%) were other acute respiratory infection (oARI), and 742 (27.0%) were isolates representing colonization. Serotypes 3 (11.3%), 19A (8.4%) and 22F (6.2%) were the most common; serotypes 1,5, and 8 were rare. Serotypes 4, 14, 7F, 9V, 12F, 14, 19A and 6C were over-represented in bacteremic disease, and serotypes 3, 6A, 11A, 19F, 23A, 23F, 35B, 35F were more common in NBPP. The proportion of cases due to PCV7 serotypes declined from 48.7% to 8.7% in bacteremic pneumonia, from 35.3% to 10.9% in NBPP, from 34.2% to 7.5% in oARI, and from 38.7% to 12.2% in colonizing isolates. In 2010-2011, PCV13 serotypes accounted for 62.6% of isolates associated with bacteremic pneumonia, 42.0% of bacteremia without pneumonia, 41.1% of NBPP, 25.7% of oARI, and 32.9% of colonizing isolates.

CONCLUSIONS

Serotype distributions differ significantly in different presentations of pneumococcal disease. Herd protection due to PCV7 has changed serotype distribution, but PCV13 serotypes remain important in all categories of disease.

Invasive pneumococcal diseases in children and adolescents--a single centre experience

Background

S. pneumoniae is a major cause of meningitis, pneumonia and sepsis in children. In 2006 universal pneumococcal vaccination was recommended in Germany for all children up to their second birthday. We have compared the prevalence and outcome of IPD at a single hospital before and after the introduction of vaccination.

Findings

55 cases of IPD were identified over an 11 year period. Almost half of the patients were younger than 2 years of age. Most of the children were affected by pneumonia. The second highest incidence seen was for meningitis and sepsis. 17 patients exhibited additional complications. Significant pre-existing and predisposing disorders, such as IRAK 4 defect, ALPS or SLE were identified in 4 patients. Complete recovery was seen in 78% of affected children; 11% had a fatal outcome and 11% suffered from long term complications. Only 31% overall had been vaccinated. The most common serotype was 14. Serotypes not covered by any of the current vaccines were also found. Antibiotic treatment commenced with cephalosporins in over 90%.

Conclusion

Frequency of IPD in our hospital did not decrease after initiation of the pneumococcal vaccination. This might be due to vaccinations not being administered satisfactorily as well as to poor education about the need of the vaccination. Pre-existing diseases must be monitored and treated accordingly and rare deficiencies taken into account when IPD takes a foudroyant course. In addition, antibiotic stewardship has been initiated at this hospital centre as a consequence of the high cephalosporin use detected in this study.

Streptococcus pneumoniae invasive infections in Burkina Faso, 2007 to 2011

OBJECTIVE

We had for aim to determine the epidemiology of meningeal and lung invasive infections due to Streptococcus pneumoniae in Burkina Faso.

MATERIAL AND METHODS

We screened for S. pneumoniae with the usual bacteriology techniques and with real time polymerase chain reaction (rt-PCR) in 7917 samples of cerebrospinal fluid (CSF) and pleural fluid (PF) collected in the Ouagadougou Yalgado Ouedraogo Teaching Hospital, from 2007 to 2011.

RESULTS

S. pneumoniae was identified in 476 (6%) samples including 455 (5.7%) in CSF and 21 (0.3%) in PF. Sixty-seven percent of invasive infections occurred in patients 15 years of age or less, without any significant sex ratio difference. The infections occurred most frequently between January and August, with the first and most important peak between January and May (dry season) and the second peak between June and August (at the beginning of rain season). The introduction of rt-PCR proved the under diagnosing of invasive infections by usual bacteriological methods (latex agglutination assay and culture).

CONCLUSION

Invasive pneumococcal infections occur mainly in patients 15 years of age or less, without any difference in sex ratio and with peaks in the dry season. Vaccinal schedules should include all age ranges in Burkina Faso.

Diagnosis of Streptococcus pneumoniae-associated hemolytic uremic syndrome

BACKGROUND

Hemolytic uremic syndrome related to pneumococcal infection (P+HUS) can be difficult to diagnose due to the lack of a specific test and the absence of a consensus for definite diagnostic criteria.

METHODS

A retrospective study was conducted on the cases that have been considered as P+HUS in the participating centers during the past 10 years. Diagnostic strategy and criteria used for the diagnosis of P+HUS were evaluated and compared with a review of literature data.

RESULTS

A total of 17 children were studied. Tests ruling out other causes of HUS were performed in 94% of cases. Direct confirmatory tests for P+HUS were done in a minority of cases as Thomsen-Friedenreich antigen testing using lectin assay were done in only 2 patients (11%). Retrospectively, the diagnosis of P+HUS was confirmed in 28% to 89% of cases depending on the already published criteria used. A literature review focused on the last 15 years confirmed these diagnostic difficulties due to variable definition criteria and bring a new light on the potential usefulness of tests used to reveal T activation in this setting.

CONCLUSION

To date, in a context of suspicion of P+HUS, no precise, practical and consensual strategy exists for T-antigen exposure diagnosis. The T-antigen activation test using peanut lectin might be the most appropriate test for a direct diagnosis of P+HUS. A large prospective study is required to confirm this hypothesis. However, before such data are available, its use could be of help when a suspicion of P+HUS is present given the therapeutic impact of such a diagnosis.

Trends in US hospital stays for Streptococcus pneumoniae-associated hemolytic uremic syndrome

BACKGROUND

Hemolytic uremic syndrome (HUS) is usually associated with diarrheal illness but can also occur in children with Streptococcus pneumoniae infection (SpHUS), particularly those with complicated pneumonia. Based on recent reports that hospital discharges for complicated pneumococcal pneumonia are increasing in US children, we studied whether discharges for SpHUS might also be increasing.

METHODS

We used the Kids' Inpatient Database samples from 1997, 2000, 2003, 2006 and 2009 to estimate trends in US hospital discharges of children (0-18 years) for whom diagnosis codes indicated invasive pneumococcal disease, HUS, or both (SpHUS). Univariate and multivariate analyses were based on 2009 discharges.

RESULTS

During the 5 study years, annual numbers of US hospital discharges for SpHUS approximately doubled (P = 0.025 for linear trend) and cumulatively totaled an estimated 211 discharges. In 2009, SpHUS accounted for 4.6% (95% confidence interval [CI]: 3.0%-6.7%) of HUS discharges, 0.7% (95% CI: 0.5%-1.0%) of invasive pneumococcal disease discharges and 3.0% (95% CI: 2.0%-3.9%) of discharges for complicated pneumococcal pneumonia. Discharges for SpHUS were more likely than those for other invasive pneumococcal disease to occur in children <3 years of age and to incur longer length of stay and greater hospital charges. SpHUS was independently associated with pneumococcal sepsis/bacteremia (age-adjusted odds ratio 3.8; 95% CI: 1.9-7.8) and complicated pneumonia (odds ratio 9.2; 95% CI: 4.1-20.7).

CONCLUSIONS

SpHUS is an uncommon but severe illness that primarily affects young children and is strongly associated with complicated pneumococcal pneumonia. US hospital stays for SpHUS appear to be increasing along with those for complicated pneumococcal pneumonia.

Update on Streptococcus pneumoniae associated hemolytic uremic syndrome

PURPOSE OF REVIEW

Streptococcus pneumoniae associated hemolytic uremic syndrome (SpHUS) is defined by the occurrence of acute hemolytic anemia, thrombocytopenia and acute kidney injury in a patient with a S. pneumoniae infection. We review the pathophysiology, clinical course, treatment and prognosis for SpHUS. We also describe an expanded classification system that uses additional diagnostic criteria to identify more patients with a high likelihood of having SpHUS.

RECENT FINDINGS

SpHUS often may be underdiagnosed because of overlapping features with disseminated intravascular coagulation (DIC) and the lack of strict diagnostic criteria. The epidemiology has changed with the emergence of different pneumococcal serotypes as newer pneumococcal vaccines have been introduced.

SUMMARY

SpHUS accounts for 5-15% of all HUS cases. The majority of SpHUS patients have pneumonia and a low mortality rate in contrast to those with meningitis, who have a more severe clinical course. Although the pathogenesis of SpHUS remains unknown, the Thomsen-Friedenreich antigen seems to play a central role. S. pneumoniae produces neuraminidase, thereby exposing the Thomsen-Friedenreich antigen on the surface of cell membranes. Thomsen-Friedenreich antigen exposure can result in hemolysis and direct endothelial injury leading to HUS phenotype. Early identification of these patients is critical so that fresh frozen plasma may be avoided.

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

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

Two cases of hemolytic uremic syndrome caused by Streptococcus pneumoniae serotype 3, one being a vaccine failure

We report two cases of Streptococcus pneumoniae-associated hemolytic uremic syndrome (SP-HUS) caused by serotype 3. One case occurred in an unvaccinated boy and 1 in a girl vaccinated with the 13-valent pneumococcal conjugate vaccine. SP-HUS must be considered in children, and conjugate vaccines may be less effective against serotype 3 than other serotypes.

In vivo capsular switch in Streptococcus pneumoniae--analysis by whole genome sequencing

Two multidrug resistant strains of Streptococcus pneumoniae – SV35-T23 (capsular type 23F) and SV36-T3 (capsular type 3) were recovered from the nasopharynx of two adult patients during an outbreak of pneumococcal disease in a New York hospital in 1996. Both strains belonged to the pandemic lineage PMEN1 but they differed strikingly in virulence when tested in the mouse model of IP infection: as few as 1000 CFU of SV36 killed all mice within 24 hours after inoculation while SV35-T23 was avirulent.

Whole genome sequencing (WGS) of the two isolates was performed (i) to test if these two isolates belonging to the same clonal type and recovered from an identical epidemiological scenario only differed in their capsular genes? and (ii) to test if the vast difference in virulence between the strains was mostly – or exclusively – due to the type III capsule. WGS demonstrated extensive differences between the two isolates including over 2500 single nucleotide polymorphisms in core genes and also differences in 36 genetic determinants: 25 of which were unique to SV35-T23 and 11 unique to strain SV36-T3. Nineteen of these differences were capsular genes and 9 bacteriocin genes.

Using genetic transformation in the laboratory, the capsular region of SV35-T23 was replaced by the type 3 capsular genes from SV36-T3 to generate the recombinant SV35-T3* which was as virulent as the parental strain SV36-T3* in the murine model and the type 3 capsule was the major virulence factor in the chinchilla model as well. On the other hand, a careful comparison of strains SV36-T3 and the laboratory constructed SV35-T3* in the chinchilla model suggested that some additional determinants present in SV36 but not in the laboratory recombinant may also contribute to the progression of middle ear disease. The nature of this determinants remains to be identified.

Necrotizing pneumonia caused by nanC-carrying serotypes is associated with pneumococcal haemolytic uraemic syndrome in children

Streptococcus pneumoniae infection is a leading cause of morbidity and mortality worldwide. One of the most severe complications of invasive pneumococcal disease (IPD) is haemolytic uraemic syndrome (HUS). This study was undertaken to determine the risk factors and role of pneumococcal neuraminidases in HUS in children with IPD. Eighteen cases of HUS and 54 patients with IPD without HUS were identified. The controls were patients with culture-confirmed IPD without HUS. Clinical and laboratory characteristics of the two groups of patients were compared. Bacterial isolates from both groups were serotyped, sequence typed and examined for their carriage of three neuraminidase genes. Necrotizing pneumonia and serotype 3 infection were significantly associated with HUS in children with IPD, suggesting that a severe pulmonary suppurating disease increase the risk of HUS. Serotype 14 was associated with necrotizing pneumonia but not HUS. Children with HUS were more likely to require surgery and had a longer duration of hospitalization. The study identified a significantly higher carriage of a neuraminidase gene, nanC, in the causative pneumococcal isolates from patients with HUS (89% versus 41%, p 0.001). The sensitivity and specificity of nanC to predict HUS were 89% and 59%, respectively. In conclusion, necrotizing pneumonia, serotype 3 infection and neuraminidase gene nanC were associated with HUS in children with IPD. The result suggests that NanC could provide an additive effect to NanA and NanB in the overall activity of pneumococcal neuraminidases to expose Thomsen-Friedenreich antigen on various cells in patients with HUS.

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

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

The management of community-acquired pneumonia in infants and children older than 3 months of age: clinical practice guidelines by the Pediatric Infectious Diseases Society and the Infectious Diseases Society of America

Evidenced-based guidelines for management of infants and children with community-acquired pneumonia (CAP) were prepared by an expert panel comprising clinicians and investigators representing community pediatrics, public health, and the pediatric specialties of critical care, emergency medicine, hospital medicine, infectious diseases, pulmonology, and surgery. These guidelines are intended for use by primary care and subspecialty providers responsible for the management of otherwise healthy infants and children with CAP in both outpatient and inpatient settings. Site-of-care management, diagnosis, antimicrobial and adjunctive surgical therapy, and prevention are discussed. Areas that warrant future investigations are also highlighted.

Streptococcus pneumoniae-associated hemolytic uremic syndrome among children in North America

BACKGROUND

To better characterize Streptococcus pneumoniae-associated hemolytic-uremic syndrome (SP-HUS), we report the largest series of SP-HUS among children in North America.

METHODS

We surveyed pediatric members of the Emerging Infections Network to identify SP-HUS cases. Respondents contributed clinical and laboratory features of these pediatric cases.

RESULTS

A total of 37 cases occurring between 1997 and 2009 were submitted. Of them, 33 cases (89%) were culture-confirmed and 4 (11%) were diagnosed clinically. The median patient age was 2 years, and 28 (76%) patients had completed their heptavalent pneumococcal conjugate vaccination (PCV7) series. Most patients presented with pneumonia (84%) and bacteremia (78%), whereas other clinical manifestations such as pericardial effusion (14%) and meningitis (11%) were less common. Of 29 patients, with bacteremia 6 (21%) had S. pneumoniae concurrently isolated from cerebrospinal fluid or pleural fluid. Severe illness was common with 35 (95%) patients requiring admission to the intensive care unit, over half requiring mechanical ventilation and chest tube placement or video-assisted thoracoscopic surgery, and 27 (73%) requiring dialysis during hospitalization. Among 30 patients with follow-up of 6 months, 7 (23%) remained dialysis dependent, 3 (10%) had undergone renal transplantation, 4 (13%) had neurologic sequelae, and 1 (3%) died. Among 24 serotyped isolates, 96% were non-PCV7 serotypes, most commonly 19A (50%), 92% are included in PCV13, and 10% were penicillin nonsusceptible (minimal inhibitory concentration >2 μg/mL).

CONCLUSIONS

North American children with SP-HUS had severe clinical manifestations and significant morbidity. In this series, nearly all cases were caused by serotypes that are not in PCV7 but are included in PCV13.

A specific polymerase chain reaction test for the identification of Streptococcus pneumoniae

Using an approach based on the comparison of arbitrary primer polymerase chain reaction (PCR) genomic profiles from oral streptococci and Streptococcus pneumoniae strains, we identified a 434-bp genomic fragment apparently specific for S. pneumoniae. From the nucleotidic sequence of this common fragment, a pair of primers was designed and tested on a set of strains comprising the major Streptococcus species. One species, S. anginosus, gave an amplification product of the same length as S. pneumoniae. Sequence comparison of the S. anginosus and S. pneumoniae amplicons revealed several variations which were used to define a new set of primers giving a 181-bp S. pneumoniae-specific fragment. The amplified fragment contains the 5' terminal part of a gene encoding a putative sugar-specific permease and an intergenic sequence. The PCR test was evaluated on 257 strains of invasive S. pneumoniae corresponding to clinical isolates and on 153 non-pneumoniae oral streptococci strains; in addition, 3 S. pseudopneumoniae strains were tested. With these primers, an amplification product was only obtained with the S. pneumoniae strains. Moreover, the test was successfully evaluated on 10 atypical S. pneumoniae strains related to pneumococcal diseases. In this study, we therefore established the capacity of a simple PCR test to discriminate S. pneumoniae from other Streptococci (including S. pseudopneumoniae), thus allowing rapid and accurate diagnosis.

Update on childhood and adolescent immunizations: selected review of US recommendations and literature: part 1

PURPOSE OF REVIEW

To provide a clinically relevant synopsis of research findings regarding childhood and adolescent vaccines.

RECENT FINDINGS

Much research confirms the safety, immunogenicity, and efficacy of specific vaccines as well as the positive impact on overall morbidity and mortality. Prevention and control strategies involve the expansion of vaccine recommendations to include more individuals and/or more vaccine doses. In addition, the role of universal infant vaccination, the advantages of even partial immunization, and the documented benefits of recently introduced vaccines are explored. The material in this review includes important areas of clinical practice improvement, such as awareness of interim recommendations or monitoring of vaccine failures. Literature on hepatitis B, rotavirus, Haemophilus influenzae type b conjugate, and pneumococcal vaccines is included in this first of two articles.

SUMMARY

New research on childhood and adolescent vaccines is anticipated to shape the practice of pediatric providers. Research will continue to provide the science to optimize protection and to promote the health and well being of all children and adolescents.

Is complement a culprit in infection-induced forms of haemolytic uraemic syndrome?

Haemolytic uraemic syndrome (HUS) accounts for the most common cause of childhood acute renal failure. Characterized by the classical triad of a microangiopathic haemolytic anaemia, thrombocytopaenia and acute renal failure, HUS occurs as a result of Shiga-toxin producing microbes in 90% of cases. The remaining 10% of cases represent a heterogeneous subgroup in which inherited and acquired forms of complement dysregulation have been described in up to 60%. Emerging evidence suggests that microbes associated with HUS exhibit interaction with the complement system. With the advent of improved genetic diagnosis, it is likely that certain cases of infection-induced HUS may be attributed to underlying defects in complement components. This review summarises the interplay between complement and infection in the pathogenesis of HUS.