Severe Pneumococcal Infection Research Articles

Immunological aspects of vaccination in HIV-infected patients

Until recently, HIV infection does not lose its relevance. In 2022, 630 000 people died and 1.3 million people became infected with the human immunodeficiency virus (HIV). HIV-positive persons develop more infectious diseases than healthy people do; the causative agents are mainly opportunistic microorganisms. Streptococcus pneumoniae is the main causative agent of infection in the lungs in HIV-infected persons. In order to prevent the development of severe pneumococcal infections and to overcome antibiotic resistance, vaccines have been developed. There are polysaccharide (PPV) and conjugate (PCV) vaccines. According to clinical recommendations, vaccination of previously unvaccinated HIV-infected patients is carried out regardless of T-helper cell level. However, no data were found on the effect of PCV13 on immunological memory cells. The purpose of this study is to assess an effect of PCV13 vaccination on the immune system in HIV-infected subjects.
 Materials and methods. The study included 200 patients with HIV infection, which were divided into two groups: I — received a dose of PCV13 (n = 100) and control group (n = 100). During the first visit, immunological and microbiological studies were carried out. On the second visit, a PCV13 was injected into the deltoid muscle. The third visit was made a year later, where immunological and microbiological studies were repeated. Participants were divided into 4 subgroups depending on CD4+ T cell level. The microbial study was done using a swab collected from the back of the throat.
 Results. During the immunological examination at visit 1, abnormalities were detected in all examined populations and immune cell subsets. At 12 months post-vaccination, the median levels of CD3+CD4+ and CD45RO+ T lymphocytes in the immunized group were higher than pre-vaccination levels compared to control group, in which the values changed insignificantly. Our data confirm the immunological effectiveness of PCV13 administration in HIV-infected patients. In patients with peripheral blood CD19+ lymphocyte deficiency, had increased microbial detection rate (p = 0.003).
 Conclusion. As a result, due to the high risk of pneumococcal pneumonia, HIV-infected patients should be immunized with a 13-valent pneumococcal conjugate vaccine.

Human IgMhiCD300a+ B Cells Are Circulating Marginal Zone Memory B Cells That Respond to Pneumococcal Polysaccharides and Their Frequency Is Decreased in People Living with HIV.

CD300a is differentially expressed among B cell subsets, although its expression in immunoglobulin (Ig)M+ B cells is not well known. We identified a B cell subset expressing CD300a and high levels of IgM (IgMhiCD300a+). The results showed that IgMhiCD300a+ B cells were CD10-CD27+CD25+IgDloCD21hiCD23-CD38loCD1chi, suggesting that they are circulating marginal zone (MZ) IgM memory B cells. Regarding the immunoglobulin repertoire, IgMhiCD300a+ B cells exhibited a higher mutation rate and usage of the IgH-VDJ genes than the IgM+CD300a- counterpart. Moreover, the shorter complementarity-determining region 3 (CDR3) amino acid (AA) length from IgMhiCD300a+ B cells together with the predicted antigen experience repertoire indicates that this B cell subset has a memory phenotype. IgM memory B cells are important in T cell-independent responses. Accordingly, we demonstrate that this particular subset secretes higher amounts of IgM after stimulation with pneumococcal polysaccharides or a toll-like receptor 9 (TLR9) agonist than IgM+CD300a- cells. Finally, the frequency of IgMhiCD300a+ B cells was lower in people living with HIV-1 (PLWH) and it was inversely correlated with the years with HIV infection. Altogether, these data help to identify a memory B cell subset that contributes to T cell-independent responses to pneumococcal infections and may explain the increase in severe pneumococcal infections and the impaired responses to pneumococcal vaccination in PLWH.

Regulation of inflammation and protection against invasive pneumococcal infection by the long pentraxin PTX3.

Streptococcus pneumoniae is a major pathogen in children, elderly subjects, and immunodeficient patients. Pentraxin 3 (PTX3) is a fluid-phase pattern recognition molecule (PRM) involved in resistance to selected microbial agents and in regulation of inflammation. The present study was designed to assess the role of PTX3 in invasive pneumococcal infection. In a murine model of invasive pneumococcal infection, PTX3 was strongly induced in non-hematopoietic (particularly, endothelial) cells. The IL-1β/MyD88 axis played a major role in regulation of the Ptx3 gene expression. Ptx3-/- mice presented more severe invasive pneumococcal infection. Although high concentrations of PTX3 had opsonic activity in vitro, no evidence of PTX3-enhanced phagocytosis was obtained in vivo. In contrast, Ptx3-deficient mice showed enhanced recruitment of neutrophils and inflammation. Using P-selectin-deficient mice, we found that protection against pneumococcus was dependent upon PTX3-mediated regulation of neutrophil inflammation. In humans, PTX3 gene polymorphisms were associated with invasive pneumococcal infections. Thus, this fluid-phase PRM plays an important role in tuning inflammation and resistance against invasive pneumococcal infection.

Characterization of the innate immune response to Streptococcus pneumoniae infection in zebrafish

Streptococcus pneumoniae (pneumococcus) is one of the most frequent causes of pneumonia, sepsis and meningitis in humans, and an important cause of mortality among children and the elderly. We have previously reported the suitability of the zebrafish (Danio rerio) larval model for the study of the host-pathogen interactions in pneumococcal infection. In the present study, we characterized the zebrafish innate immune response to pneumococcus in detail through a whole-genome level transcriptome analysis and revealed a well-conserved response to this human pathogen in challenged larvae. In addition, to gain understanding of the genetic factors associated with the increased risk for severe pneumococcal infection in humans, we carried out a medium-scale forward genetic screen in zebrafish. In the screen, we identified a mutant fish line which showed compromised resistance to pneumococcus in the septic larval infection model. The transcriptome analysis of the mutant zebrafish larvae revealed deficient expression of a gene homologous for human C-reactive protein (CRP). Furthermore, knockout of one of the six zebrafish crp genes by CRISPR-Cas9 mutagenesis predisposed zebrafish larvae to a more severe pneumococcal infection, and the phenotype was further augmented by concomitant knockdown of a gene for another Crp isoform. This suggests a conserved function of C-reactive protein in anti-pneumococcal immunity in zebrafish. Altogether, this study highlights the similarity of the host response to pneumococcus in zebrafish and humans, gives evidence of the conserved role of C-reactive protein in the defense against pneumococcus, and suggests novel host genes associated with pneumococcal infection.

Rapid genome sequencing identifies novel variants in complement factor I.

Complement factor I deficiency (CFID; OMIM #610984) is a rare immunodeficiency caused by deficiencies in the serine protease complement factor I (CFI). CFID is characterized by predisposition to severe pneumococcal infection, often in infancy. We report a previously healthy adolescent male who presented with respiratory failure secondary to pneumococcal pneumonia and severe systemic inflammatory response. Rapid genome sequencing (rGS) identified compound heterozygous variants in CFI in the proband, with a novel maternally inherited likely pathogenic variant, a single nucleotide deletion resulting in premature stop (c.1646del; p.Asn549ThrfsTer25) and a paternally inherited novel likely pathogenic deletion (Chr 4:110685580-110692197del).

Detection of pneumococcus during hospitalization for SARS-CoV-2.

Infections with respiratory viruses [e.g. influenza and respiratory syncytial virus (RSV)] can increase the risk of severe pneumococcal infections. Likewise, pneumococcal coinfection is associated with poorer outcomes in viral respiratory infection. However, there are limited data describing the frequency of pneumococcus and SARS-CoV-2 coinfection and the role of coinfection in influencing COVID-19 severity. We, therefore, investigated the detection of pneumococcus in COVID-19 inpatients during the early pandemic period. The study included patients aged 18 years and older, admitted to the Yale-New Haven Hospital who were symptomatic for respiratory infection and tested positive for SARS-CoV-2 during March-August 2020. Patients were tested for pneumococcus through culture-enrichment of saliva followed by RT-qPCR (to identify carriage) and serotype-specific urine antigen detection (UAD) assays (to identify presumed lower respiratory tract pneumococcal disease). Among 148 subjects, the median age was 65 years; 54.7% were male; 50.7% had an ICU stay; 64.9% received antibiotics; and 14.9% died while admitted. Pneumococcal carriage was detected in 3/96 (3.1%) individuals tested by saliva RT-qPCR. Additionally, pneumococcus was detected in 14/127 (11.0%) individuals tested by UAD, and more commonly in severe than moderate COVID-19 [OR: 2.20; 95% CI: (0.72, 7.48)]; however, the numbers were small with a high degree of uncertainty. None of the UAD-positive individuals died. Pneumococcal lower respiratory tract infection (LRTI), as detected by positive UAD, occurred in patients hospitalized with COVID-19. Moreover, pneumococcal LRTI was more common in those with more serious COVID-19 outcomes. Future studies should assess how pneumococcus and SARS-CoV-2 interact to influence COVID-19 severity in hospitalized patients.

P076: Pneumococcal infection in splenectomised Hodgkin lymphoma patients: Do they pose a problem today and what is the best long-term strategy?

Purpose: Diagnostic laparotomy and splenectomy (DLS) were introduced for Hodgkin lymphoma (HL) patients in Sweden in the late 1960s/early-70s. It was soon established that splenectomised and functional hyposplenic (following irradiation) HL patients carried an increased risk of overwhelming infections, Streptococcus pneumoniae being the major causative agent. Despite this, DLS remained as a staging procedure for more than two decades. The purpose of this study was to compare incidence and outcome of pneumococcal infections between splenectomised (spl+) and non-splenectomised (spl-) HL patients. Material and Methods: HL patients diagnosed 1973–1995 were identified in the Swedish Cancer Register. Information on splenectomies and severe pneumococcal infections was retrieved from the National Inpatient Register. Follow-up started a diagnosis and ended on date of infection, emigration, death, or December 31, 2010, whichever came first. Splenectomy was analysed as a time-varying covariate, i.e., patients were considered unexposed before the date of splenectomy and exposed after the date of splenectomy. Cox proportional hazard models were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) comparing infection rates between spl+/spl- patients. Results: A total of 4,237 HL patients were included, among whom 735 (17%) underwent a splenectomy, with a median time from splenectomy to infection of 6.8 years (range 0.1–30.8 years). The number of patients experiencing a severe pneumococcal infection was 39 (3.2 per 1,000 person-years) among spl+ and 60 (1.7 per 1,000 person-years) among spl- patients. The relative rate of severe pneumococcal infection comparing spl+/spl- HL patients was 2.43 (95% CI: 1.55–3.81), adjusted for diagnosis year, diagnosis age, and sex. The 30-day post-infection mortality proportion was 9/39 (23%) among the spl+ and 18% (11/60) among the spl- patients. Broken down by calendar period of infection, the 30-day post-infection mortality proportion among splenectomised patients was 44% (1973–1985), 23% (1986–1998), and 0% (1999–2010). Conclusion: Severe pneumococcal disease is a serious event that is more likely to appear in splenectomised HL patients compared to non-splenectomised, possibly many years after diagnosis. However, the low proportion of deaths in later decades is reassuring, and likely a result of adequate pneumococcal vaccination together with patient and doctor education about the infection risk.

Review on Pneumococcal Infection in Children.

Childhood pneumococcal infection is a growing concern among paediatricians especially, in countries where there is no routine vaccination program against Streptococcal pneumoniae. The disease is associated with significant morbidity and mortality in young children particularly those who are under the age of two years. Its main virulent factors include polysaccharide capsule, autolysin, pneumolysin, choline-binding Protein A, the higher chance for genetic transformation, and the presence of pilli that facilitate enhanced binding of bacteria to host cellular surfaces. More severe and invasive pneumococcal infections are seen in children with immunodeficiencies, hypofunctional spleen, malnutrition, chronic lung disease and nephrotic syndrome. The disease spectrum includes a range of manifestations from trivial upper respiratory tract infections to severe invasive pneumococcal disease (PD). The basis of diagnosis is the isolation of bacteria in the culture of body fluids including blood. Antibiotics are best guided by sensitivity patterns and the emergence of resistance is a growing concern.

Erythrocyte T-antigen activation in children: Patient characteristics and the hemolytic risk of transfusion.

T-antigen activation usually occurs upon red blood cell (RBC) membrane cryptantigen exposure due to bacterial enzymes. Although uncommon, the condition is probably underrecognized. There is concern about hemolysis after plasma and plasma-containing platelet transfusions due to naturally occurring anti-T antibody in healthy blood donors. However, experts have debated the extent and severity of clinical hemolysis due to anti-T. We retrospectively identified patients who tested positive for polyagglutination with Arachis hypogea and Glycine max lectins from 2008 to 2019. The records of the patients were reviewed to determine clinical symptoms, laboratory evidence of hemolysis, need for transfusion, and clinical outcomes. Ten patients were identified. At diagnosis, all were anemic and four had thrombocytopenia. Severe Streptococcus pneumoniae infection affected seven patients; one died. Seven of 10 patients (70%) had laboratory evidence of hemolysis. Peripheral blood smear findings in six patients included RBC agglutination and changes suggesting hemolysis (spherocytes and schistocytes), but three had unremarkable RBC morphology. Four patients required plasma or platelet transfusions; all survived to discharge. T-antigen activation is a rare entity. Most patients diagnosed at our hospital had hemolytic anemia and severe pneumococcal infection. Hemoglobin decreased after plasma and platelet transfusions in all patients assessed, but these transfusions were necessary to support treatment. RBCs were given to maintain appropriate hemoglobin levels.

The search for novel treatment strategies for Streptococcus pneumoniae infections.

ABSTRACTThis review provides an overview of the most important novel treatment strategies against Streptococcus pneumoniae infections published over the past 10 years. The pneumococcus causes the majority of community-acquired bacterial pneumonia cases, and it is one of the prime pathogens in bacterial meningitis. Over the last 10 years, extensive research has been conducted to prevent severe pneumococcal infections, with a major focus on (i) boosting the host immune system and (ii) discovering novel antibacterials. Boosting the immune system can be done in two ways, either by actively modulating host immunity, mostly through administration of selective antibodies, or by interfering with pneumococcal virulence factors, thereby supporting the host immune system to effectively overcome an infection. While several of such experimental therapies are promising, few have evolved to clinical trials. The discovery of novel antibacterials is hampered by the high research and development costs versus the relatively low revenues for the pharmaceutical industry. Nevertheless, novel enzymatic assays and target-based drug design, allow the identification of targets and the development of novel molecules to effectively treat this life-threatening pathogen.

Nasopharyngeal Colonization and levofloxacin Susceptibility of Streptococcus pneumoniae among Healthcare Workers in a Teaching Hospital in Tehran, Iran

Background: Streptococcus pneumoniae commonly asymptomatically colonizes the human upper respiratory tract and the carriage rate varies between geographical regions. The colonized individuals are not only at risk of infections but also can be a source of transmission of the pathogen. The risk of the droplet or airborne transmission of pneumococcal strains healthcare workers is considerable. The current study aimed to determine the extent of nasopharyngeal colonization with S. pneumoniae and their levofloxacin susceptibility at a tertiary hospital in Tehran, Iran. Materials and Methods: During a six-month period, the nasopharyngeal swab samples collected from 300 volunteer healthcare workers of Imam Hossein Hospital. Samples screened for S. pneumoniae using standard conventional biochemical methods. The minimum inhibitory concentration (MIC) of levofloxacin was determined using a commercially available strip antibiotic test according to the clinical laboratory standards institute (CLSI) guidelines. Results: A total of 19 (6.3%) enrolled healthcare workers were colonized with S. pneumoniae. Amongst the enrolled volunteers, nurses had a higher rate of pneumococcal colonization (47.3%) followed by interns (21%) and laboratory workers (15.8%). Our analysis revealed that there was a significant correlation between smoking and pneumococcal colonization. The antimicrobial susceptibility testing showed that all of the isolates were susceptible to levofloxacin (MIC≤2 μg/ml). Conclusion: This low rate of pneumococcal colonization amongst healthcare professionals may be attributed to the low risk of horizontal transmission of severe pneumococcal infections in the hospital. Additionally, our findings indicated that levofloxacin was an effective antimicrobial agent for the treatment of pneumococcal infections.

Splenic volume in pneumococcal pneumonia patients is associated with disease severity and mortality

Splenectomy is a risk factor for serious pneumococcal disease like overwhelming post-splenectomy infection (OPSI). In healthy individuals with small spleen, fulminant pneumococcal infection similar to OPSI has been reported. Furthermore, it is reported that small spleen was associated with severe pneumococcal infection patients treated in an intensive care unit. However, the association between the small spleen and pneumococcal pneumonia was not investigated enough.We retrospectively analyzed patients with pneumococcal pneumonia who underwent computed tomography examination with measurement of the splenic volume at Harasanshin Hospital between 2004 and 2019. Data on their background characteristics, laboratory findings, and clinical courses were collected.413 patients were included in the final analysis. The splenic volume was significantly lower in the moderate (P < 0.001), severe (P < 0.00005), and extremely severe (P < 0.001) pneumonia groups compared with the mild pneumonia group. Furthermore, the splenic volume was significantly lower in patients died within 30 days of pneumonia treatment (median of 73.49 versus 110.77 cm3, P < 0.005) or during hospitalization (median of 71.69 versus 111.01 cm3, P < 0.0005). Splenic volume <40 cm3 was significantly associated with mortality within 30 days and total hospital mortality as a risk factor in univariate analysis. Splenic volume <40 cm3 was an independent risk factor for mortality within 30 days (odds ratio: 5.0, 95% confidence interval: 1.2–21.1, P < 0.05) and total hospital mortality (odds ratio: 7.4, 95% confidence interval: 1.8–30.6, P < 0.01) in multivariate logistic regression analysis.These results suggest that small spleen is a risk factor for severity and mortality of pneumococcal pneumonia.

Pneumococcal infection transmission between family members with congenital asplenia: A case report

BACKGROUNDAsplenia, the lack of a spleen, can be congenital and increases susceptibility to severe infections caused by encapsulated bacteria, such as Streptococcus pneumoniae (S. pneumoniae). We report two cases of severe pneumococcal infection in two asplenic family members living in the same household.CASE SUMMARYPatient 1, a 38-year-old man with a history of congenital hepatitis B infection and hypospadias, was brought to our emergency department with complaints of cyanosis, cough, and edema of his limbs. He was clinically diagnosed as hyposplenic with overwhelming pneumococcal sepsis. He was admitted to the intensive care unit and was administered antibiotics and catecholaminergic therapy but died 2 h after admission. Patient 2, a 63-year-old woman with a history of type 2 diabetes, was brought to our emergency department one month after admission of Patient 1. She was diagnosed as asplenic with overwhelming pneumococcal sepsis. History-taking revealed that she was the mother of Patient 1 and the two had lived in the same household. She was admitted to the intensive care unit and was rapidly provided antibiotics and catecholaminergic intervention but died one day after admission.CONCLUSIONPneumococcal bacteremia caused by virulent S. pneumoniae may be transmitted within households. All residents of households where individuals with pneumococcal bacteremia are living should be educated about the risk of transmissibility. Family members of patients with congenital asplenia/hyposplenia, all family members should be examined to assess their splenic function.

Safety and Efficacy of Pneumococcal Vaccination in Pediatric Nephrotic Syndrome.

Nephrotic syndrome affects both children and adults. Idiopathic nephrotic syndrome is reported to be one of the most frequent renal pathologies in childhood. Nephrotic children are at high risk for severe pneumococcal infections as one of the life-threatening complications of nephrotic syndrome due to involvement of the immunosuppressive regimen and the acquired immune deficiency induced by nephrotic syndrome including decreased plasma IgG and low complement system components. Aiming to prevent pneumococcal infection is of paramount importance especially in this era of ever-increasing pneumococcal resistance to penicillins and cephalosporins. The pneumococcal vaccines currently available are inactivated vaccines—the two main forms in use are polysaccharide vaccines and conjugated vaccines. However, the data supporting the use of these vaccines and to guide the timing and dosage recommendations is still limited for nephrotic children. Thus, this review discusses the evidences of immunogenicity and safety profile of both vaccinations on nephrotic patients as well as the effect of nephrotic syndrome treatment on vaccine seroresponses.

STREPTOCOCCUS PNEUMONIAE SEROTYPE DISTRIBUTION AFTER THE INTRODUCTION OF PNEUMOCOCCAL CONJUGATE VACCINES

Streptococcus pneumoniae serotypes are changing due to the widely introduced pneumococcal conjugate vaccines. Surveillance studies have proven valuable in monitoring these vaccine effects. S. pneumoniae is highly adaptable to its human reservoir and colonises mucosal surfaces of upper airways mainly in children. Carriage decreases during the first 2 years of life because of the development of naturally acquired adaptive immune memory. Most of the serotypes do not cause serious illnesses but few of them are responsible for severe pneumococcal infections. Ten of the most common serotypes are estimated to cause over 60% of invasive diseases worldwide. The virulence factor of S. pneumoniae is the polysaccharide capsule as non-encapsulated strains are absent among the strains causing invasive pneumococcal disease. Prevalence of serotypes differs depending on the age group and geographic area of patients. Differences in PCV implementation lead to changes in serotype distribution and to significant reduction of disease caused by vaccine types.

Impact of the introduction of a 13-valent pneumococcal vaccine on pneumococcal serotypes in non-invasive isolates from 2007 to 2016 at a teaching hospital in Japan

To prevent severe invasive pneumococcal infection, pneumococcal conjugate vaccines (PCVs) were introduced in Japan in 2010, and in 2013 a pneumococcal 13-valent conjugate vaccine (PCV13) was included in the routine vaccination schedule for infants. In this study, we analysed the antimicrobial susceptibilities and capsular types of pneumococci isolated from non-invasive patient sites from 2007 to 2016 to assess the impact of the introduction of PCV13. A total of 618 pneumococcal isolates collected at a teaching hospital from 2007 to 2016 were used. These isolates were characterized by capsular typing, multilocus sequence typing and antimicrobial susceptibility testing. Capsular typing indicated that, after the introduction of the PCV, the proportion of PCV13 serotypes decreased (P<0.01), while non-PCV13 serotypes became diverse. In particular, increases in 22 F, 15A and 23A were noted among non-PCV13 serotypes. Regarding antimicrobial susceptibility, the non-susceptibility rate to penicillin of pneumococci that showed higher minimum inhibitory concentrations (MICs) than the susceptibility breakpoint decreased, and pneumococci tended to become susceptible. However, all type 23A pneumococci and 77.8 % of type 15A pneumococci showed the reverse trend, with low susceptibility to penicillin. Furthermore, all 15A and 23A isolates had macrolide resistance genes. These data suggest that PCVs can prevent infections caused by PCV serotypes. However, since non-PCV13-type pneumococci, in particular 15A and 23A, which have acquired multidrug resistance, have already emerged over time, the development of a novel vaccine targeting a broader spectrum of pneumococci is warranted.

Congenitally impaired pattern-recognition receptors in pathogenesis of pediatric invasive and recurrent pneumococcal infection

Here we review currently available data showing that innate immune signs predisposing to recurrent and invasive pneumococcal infections were identified in children. Streptococcus pneumoniae (pneumococcus) belongs to Grampositive bacteria being the major cause of morbidity and mortality in infants, especially in developing countries and in communities with low socioeconomic status. Due to the lack of anti-pneumococcal vaccination, the significant proportion of pneumococcus carriers develop non-invasive (pneumonia, otitis media, sinusitis) and severe invasive (bacteremia/septicemia, meningitis) pneumococcal infection. A great deal of diverse factors related to pneumococcus biological features (virulence factors) as well individualized host-specific immunity are implicated in efficient bacterial penetration across the mucous membranes. The TLR signaling system plays a crucial role in the human nonspecific defense upon the first encounter with the pathogen. Various TLRs comprise the first pattern recognition receptor fami ly ever described which sense ligands derived from the outer bacterial wall. The complement system is the ancient innate immunity component mainly involved in intravascular elimination of bacterial agents. In addition, the complement proteins serve as a bridge between innate and adaptive immunity, ensuring optimal conditions for B- and T-cell maturation and differentiation. Because pneumococcus secretes the IgA protease, a local protective effects related to IgA antibodies might not be so prominent. Therefore, B-cell immunodeficiency and impaired complement system hold a lead place among congenital causes resulting in severe and recurrent pneumococcal infections in children. Thus, based on available data, we concluded that impaired B-cell function, the complement components deficiency as well as receptor-recognition receptors (TLR-2, -9, -4, MYD88 adapter protein, TLR cascade enzymes: IRAK4, NEMO, NOD-like receptors: NOD2, NLRP3; C-type lectins: MBL, Dextin-2, and, possibly, ficoline) play the most important role among congenital immunodeficiencies predisposing to invasive and recurrent pneumococcal infections play the most important role among congenital immunodeficiencies predisposing to invasive and recurrent pneumococcal infections, and should be used as a rationale for immunological surveillance and organizing immunogenetics screening in these patients.

Utility of MALDI-TOF MS as a new tool for Streptococcus pneumoniae serotyping.

Nowadays, more than 95 different Streptococcus pneumoniae serotypes are known, being less than one third responsible for the majority of severe pneumococcal infections. After the introduction of conjugate vaccines, a change in the epidemiology of the serotypes causing invasive pneumococcal disease has been observed making the surveillance of circulating serotypes especially relevant. Some recent studies have used matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) technology to identify the most frequent pneumococcal serotypes that cause invasive disease. The objectives of this study were to evaluate the efficacy of previously described discriminatory peaks determined by MALDI-TOF MS for the identification of serotypes 6B, 19F, 19A and 35B using reference and clinical isolates and to try to identify other discriminatory peaks for serotypes 11A, 19F and 19A using transformed pneumococcal strains. Most of the proposed peaks defined in the literature for the identification of serotypes 6B, 19F, 19A, 35B were not found in the spectra of the 10 reference isolates nor in those of the 60 clinical isolates tested corresponding to these four serotypes. The analysis and comparison of the mass spectra of genetically modified pneumococci (transformed strains) did not allow the establishment of new discriminatory peaks for serotypes 11A, 19F, and 19A. MALDI-TOF MS in the usual range of 2,000 to 20,000 m/z did not prove to be a valid technique for direct S. pneumoniae serotyping.

Immunogenicity and Immune Memory after a Pneumococcal Polysaccharide Vaccine Booster in a High-Risk Population Primed with 10-Valent or 13-Valent Pneumococcal Conjugate Vaccine: A Randomized Controlled Trial in Papua New Guinean Children

We investigated the immunogenicity, seroprotection rates and persistence of immune memory in young children at high risk of pneumococcal disease in Papua New Guinea (PNG). Children were primed with 10-valent (PCV10) or 13-valent pneumococcal conjugate vaccines (PCV13) at 1, 2 and 3 months of age and randomized at 9 months to receive PPV (PCV10/PPV-vaccinated, n = 51; PCV13/PPV-vaccinated, n = 52) or no PPV (PCV10/PPV-naive, n = 57; PCV13/PPV-naive, n = 48). All children received a micro-dose of PPV at 23 months of age to study the capacity to respond to a pneumococcal challenge. PPV vaccination resulted in significantly increased IgG responses (1.4 to 10.5-fold change) at 10 months of age for all PPV-serotypes tested. Both PPV-vaccinated and PPV-naive children responded to the 23-month challenge and post-challenge seroprotection rates (IgG ≥ 0.35 μg/mL) were similar in the two groups (80–100% for 12 of 14 tested vaccine serotypes). These findings show that PPV is immunogenic in 9-month-old children at high risk of pneumococcal infections and does not affect the capacity to produce protective immune responses. Priming with currently available PCVs followed by a PPV booster in later infancy could offer improved protection to young children at high risk of severe pneumococcal infections caused by a broad range of serotypes.

Treatment with broadly neutralizing influenza antibodies reduces severity of secondary pneumococcal pneumonia in mice.

Secondary bacterial pneumonia is a frequent complication of influenza, associated with high morbidity and mortality. We hypothesized that treatment with neutralizing influenza A antibody AT10_002 protects against severe secondary pneumococcal infection in a mouse model of influenza A infection. Influenza A (H3N2) virus–infected male C57Bl6 mice were treated intravenously with either AT10_002 or a control 2 days postinfection. Seven days later, both groups were infected with Streptococcus pneumoniae and killed 18 hours later. Mice receiving AT10_002 showed less loss of bodyweight compared with controls (+1% vs −12%, P < .001), lower viral loads in bronchoalveolar lavage fluids (BALFs) (7 vs 194 RNA copies per µL; P < .001), and reduced bacterial outgrowth in lung homogenates (3.3 × 101 vs 2.5 × 105 colony‐forming units per mg; P < .001). The treatment group showed lower pulmonary wet weights, lower cell counts, and lower protein levels in BALF compared with controls. Treatment with AT10_002 was associated with lower levels of tumor necrosis factor‐α, interleukin (IL)‐6, cytokine‐induced neutrophil chemoattractant (KC), and interferon‐γ in BALF and lower IL‐6 and KC in lung homogenates. Treatment with anti‐influenza antibody AT10_002 is associated with reduced weight loss, viral load, bacterial outgrowth, and lung injury in a murine model of secondary pneumococcal pneumonia following influenza infection.