Pneumococcal immunization in immunocompromised hosts: where do we stand?

Etiology of meningitis among adults in three quaternary hospitals in Mozambique, 2016-2017: The role of HIV

BACKGROUND

Meningitis remains an important cause of morbi-mortality in adults in sub-Saharan Africa. Data on the etiological investigation of meningitis in adults in Mozambique is limited and most studies were conducted in southern Mozambique. Identification of the etiology of meningitis in adults are crucial to guide prevention and treatments strategies. In this study, we determine the burden of fungal and bacterial meningitis among adults at the three largest hospitals in Mozambique.

METHOD

We performed analysis of data from the routine sentinel surveillance system for meningitis in Mozambique from January 2016 to December 2017. Cerebrospinal fluid (CSF) samples were collected from eligible adults (≥18 years old) who met World Health Organization (WHO) case definition criteria for Meningitis. All samples were tested by cryptococcal antigen (CrAg) lateral flow assay (LFA), culture and triplex real-time polymerase chain reaction (qPCR) assay and all patients were tested for human immunodeficiency virus (HIV) using the national algorithm for HIV testing.

RESULTS

Retrospective analysis of 1501 CSF samples from adults clinically suspected of meningitis revealed that 10.5% (158/1501) were positive for bacterial and fungal meningitis. Of these 158 confirmed cases, the proportion of Cryptococcal meningitis and pneumococcal meningitis was38.6% (95% CI: 31.0% to 46.7%) and 36.7% (95% CI: 29.2% to 44.7%), respectively. The other bacterial agents of meningitis identified include Neisseria meningitidis (8.9%; 14/158), Escherichia coli (6.3%; 10/158), Haemophilus influenzae (5.1%; 8/158) and S. aureus (4.4%; 7/158), which represent (24.7%; 39/158) of the total confirmed cases.

CONCLUSION

Altogether, our findings show a high burden of Cryptococcal meningitis among adults in Mozambique, especially in people living with HIV, followed by pneumococcal meningitis. Our findings suggest that rollout of CrAg Lateral Flow Assay in the health system in Mozambique for early detection of cryptococcus neoformans is necessary to improve overall patient care.

Reducing infectious complications after allogeneic stem cell transplant

INTRODUCTION

Infections remain a significant problem, in patients undergoing an allogeneic hematopoietic stem-cell transplant (HSCT) and efforts have been made over the years, to reduce the incidence, morbidity and mortality of infectious complications.

AREAS COVERED

This manuscript is focused on the epidemiology, risk factors and prevention of infections after allogeneic HSCT. A systematic literature review was performed using the PubMed database, between November 2019 and January 2020, with the following MeSH terms: stem-cell transplantation, infection, fungal, bacterial, viral, prophylaxis, vaccines, prevention. The authors reviewed all the publications, and following a common revision, a summary report was made and results were divided in three sections: bacterial, fungal and viral infections.

EXPERT OPINION

Different infections occur in the early, intermediate and late post-transplant period, due to distinct risk factors. Improved diagnostic techniques, pre-emtive therapy and better prophylaxis of immunologic complications, have reduced the morbidity and mortality of infections. The role of the gut microbiota is under careful scrutiny and may further help us to identify high-risk patients.

Vaccine strategies to reduce the burden of pneumococcal disease in HIV-infected adults in Africa

INTRODUCTION

Streptococcus pneumoniae is the leading cause of invasive bacterial disease, globally. Despite antiretroviral therapy, adults infected with human immunodeficiency virus (HIV) are also at high risk of pneumococcal carriage and disease. Pneumococcal conjugate vaccines (PCVs) provide effective protection against vaccine serotype (VT) carriage and disease in children, and have been introduced worldwide, including most HIV-affected low- and middle-income countries. Unlike high-income countries, the circulation of VT persists in the PCV era in some low-income countries and results in a continued high burden of pneumococcal disease in HIV-infected adults. Moreover, no routine vaccination that directly protects HIV-infected adults in such settings has been implemented.

AREAS COVERED

Nonsystematic review on the pneumococcal burden in HIV-infected adults and vaccine strategies to reduce this burden.

EXPERT OPINION

We propose and discuss the relative merit of changing the infant PCV program to use (1a) a two prime plus booster dose schedule, (1b) a two prime plus booster dose schedule with an additional booster dose at school entry, to directly vaccinate (2a) HIV-infected adults or vaccinating (2b) HIV-infected pregnant women for direct protection, with added indirect protection to the high-risk neonates. We identify key knowledge gaps for such an evaluation and propose strategies to overcome them.

Immunogenicity and safety of the 13-valent pneumococcal conjugate vaccine in patients with immunocompromising conditions: a review of available evidence

Immunocompromising conditions increase the risk of invasive pneumococcal disease (IPD). Vaccine uptake in patients with these conditions may be low in part because of concerns about decreased immunogenicity and safety in these high-risk groups. We conducted a literature search to identify publications describing antibody responses to 13-valent pneumococcal conjugate vaccine (PCV13) in immunocompromised individuals recommended for PCV13 vaccination by the US Advisory Committee on Immunization Practices (ACIP). This review summarizes immunogenicity data from 30 publications regarding the use of PCV13 comprising 2406 individuals considered at high risk for IPD by the ACIP. Although antibody responses to PCV13 in individuals with immunocompromising and high-risk conditions were variable and generally lower compared with healthy controls, the vaccine was immunogenic and was largely well tolerated. Based on these findings, concerns regarding immunogenicity and safety of PCV13 are not supported and should not be barriers to vaccination in high-risk populations.

Predictors of antibody persistence to the 7-valent pneumococcal conjugate vaccine in healthy Fijian infants at 12 months of age

Little is known about the predictors of antibody persistence to pneumococcal conjugate vaccines (PCV) in the context of reduced dose schedules. In Fiji, an RCT investigated 0, 1, 2 and 3 dose schedules of 7-valent PCV administered at 6, 10 and 14 weeks of age in 364 healthy infants. This study was a post-hoc analysis of the predictors of poor antibody persistence at 12 months, prior to a booster, using univariable and multivariable analyses. The strongest predictors of poor antibody persistence as measured by serotype-specific immunoglobulin G (IgG) and opsonophagocytosis (OI) assays were being of Indigenous Fijian ethnicity (IgG: adjusted odds ratio (aOR) 3.43, p < 0.001; OI: aOR 1.96, p = 0.013) and receipt of fewer than 3 doses of PCV. These findings may help to identify which children may be at an increased risk of pneumococcal disease in the context of reduced dose primary series PCV schedules.

Pneumococcal Vaccination Strategies Among HIV-infected Adult Patients: A Review of the Literature

BACKGROUND/AIM

Streptococcus pneumoniae is the leading cause of bacterial pneumonia and an important cause of invasive disease. Despite the antiretroviral therapies, adults infected with human immunodeficiency virus (HIV) are at particular risk for invasive pneumococcal disease (IPD). The purpose of this study was to report the efficacy of the strategies currently being used in pneumococcal vaccination for HIV-infected adults.

MATERIALS AND METHODS

A literature search was performed through electronic databases, for original articles in English, from years 2000 to 2019. Clinical trials controlled or randomized, and cohort studies were included.

RESULTS

While 23-valent pneumococcal polysaccharide vaccine (PPV23) is recommended for immunocompromised patients, it has been reported that it is less suitable for HIV-infected patients. Recent guidelines have added pneumococcal conjugate vaccine (PCV) to the list of recommended vaccines.

CONCLUSION

Further studies are needed to determine the optimal vaccines and intervals for subsequent revaccinations during the lifetime.

Trends in Invasive Pneumococcal Disease in Cancer Patients After the Introduction of 7-valent Pneumococcal Conjugate Vaccine: A 20-year Longitudinal Study at a Major Urban Cancer Center

Background

Rates of invasive pneumococcal disease (IPD) declined since routine childhood immunization with the 7-valent pneumococcal conjugate vaccine (PCV7) in 2000. We studied the impact of PCV7 on the incidence of IPD in cancer patients.

Methods

This was a retrospective analysis of adult and pediatric patients treated at Memorial Sloan Kettering Cancer Center from 1992 to 2012. Recovery of Streptococcus pneumoniae from a sterile site defined IPD. IPD incidence was calculated as cases per 1,000 unique patient-visits per year (UPV). IPD incidence was calculated for the periods: "before PCV7" (1992-2000), "after PCV7" (2001-2010) and "after PCV13" (2011-2012).

Results

Of 343 IPD cases, 165, 155, and 23 cases occurred "before PCV7," "after PCV7" and "after PCV13" respectively. The IPD incidence declined from 0.43 "before PCV7" to 0.17 "after PCV7" (95% confidence interval [CI]: 0.33-0.46, P < .001) and 0.11 "after PCV13" (95% CI: 0.42-0.96, P = .004). Adults with hematologic malignancies and children had the highest incidence. In patients 1-4 years old, the incidence declined from 11.2 "before PCV7" to 2.38 "after PCV7" (79% decrease, 95% CI: 0.1-0.4, P < .001). In patients with hematologic malignancies, the incidence declined from 2.55 "before PCV7" to 0.92 "after PCV7" (64% decrease, 95% CI: 0.27-0.47, P < .001).

Conclusions

The incidence of IPD among cancer patients sharply declined after introduction of PCV7; especially in high risk groups. The decline in adults suggests an indirect effect from PCV7 childhood vaccination.

Immunogenicity and safety of single-dose, 13-valent pneumococcal conjugate vaccine in pediatric and adolescent oncology patients

BACKGROUND

Children receiving immunosuppressive treatment for cancer are at high risk for invasive pneumococcal disease. The 13-valent pneumococcal conjugate vaccine (PCV13) can prevent pneumococcal disease in healthy children; however, there is an absence of literature regarding the benefit of PCV13 in immunocompromised children with cancer.

METHODS

A prospective, open-label cohort study recruited children between ages 1 and 18 years who were receiving active immunosuppressive therapy (AIT) or were within 12 months after completing immunosuppressive therapy (CIT). Blood samples were taken before and 4 weeks after the administration of single-dose PCV13. Serotype-specific immunoglobulin G antibody titers were measured, and titers ≥0.35 μg/mL were considered protective. Solicited side effects were recorded in a 7-day diary after vaccination.

RESULTS

Eighty-five children were recruited. At baseline, ≤50% had protective antibody titers against Streptococcus pneumoniae for 10 serotypes in the AIT group and for 8 serotypes in the CIT group. Postvaccination, ≥70% had protective antibody titers for 9 and 11 serotypes in the AIT and CIT groups, respectively. Both groups had comparable responses to PCV7 serotypes, whereas a significantly higher proportion in the CIT group achieved protective antibody titers to PCV13 serotypes. There was a low rate of serious adverse events (3.5%).

CONCLUSIONS

A single-dose of PCV13 is safe and immunogenic in children diagnosed with cancer. All children who are receiving therapy for cancer should receive a single dose of PCV13 as soon as possible after diagnosis, regardless of prior PCV exposure. The current data support the recommendation for an additional dose of PCV13 after the completion of immunosuppressive therapy to provide additional protection against invasive pneumococcal disease. Cancer 2017;123:4215-4223. © 2017 American Cancer Society.

Epidemiology of bloodstream infections in patients with myeloma receiving current era therapy

BACKGROUND

Bloodstream infections (BSIs) are a significant complication of treatment for multiple myeloma (MM). The objective of this study was to define the epidemiology of BSI with current era MM treatment regimens, including immunomodulatory drugs, proteasome inhibitors and autologous haematopoietic stem cell transplantation (ASCT).

METHODS

Clinical and microbiology records of patients with MM diagnosed between 2008 and 2012 were reviewed using a standardised tool to capture patient demographics, myeloma characteristics and BSI characteristics (type, severity, outcomes). Conditional risk set modelling was used to determine clinical predictors of BSI.

RESULTS

Of 199 studied patients, 71 (35.6%) had confirmed BSI (98 infection episodes). Peak incidence was 65.1 infections/100 patient-years at 4-6 months following MM diagnosis with a late peak at 64-66 months. Gram-positive pathogens were responsible for the majority (54.5%) of infections during induction, whilst gram-negative pathogens were responsible for the majority (57.7%) of infections during disease progression. Overall, Escherichia coli was the most frequently identified pathogen. Streptococcus pneumoniae comprised 6.1% of all BSIs at a median of 7.5 months following MM diagnosis. Highest rates of ICU admission (23.1%) and mortality (11.5%) were seen with BSIs in patients with progressive disease. Recent ASCT was independently associated with increased BSI risk (HR 3.09, P = 0.05).

CONCLUSIONS

Treatment of progressive disease is a high-risk period for infection, evidenced by high proportions of BSI due to gram-negative pathogens and S. pneumoniae. Targeted evaluation of preventative strategies (prophylaxis, vaccination) to reduce morbidity and mortality during this period is required.

Pneumococcal Vaccination Strategies. An Update and Perspective

Streptococcus pneumoniae is an important global pathogen that causes a wide range of clinical disease in children and adults. Pneumococcal pneumonia is by far the common presentation of noninvasive and invasive pneumococcal disease and affects the young, the elderly, and the immunocompromised disproportionately. Patients with chronic pulmonary diseases are also at higher risk for pneumococcal infections. Substantial progress over the century has been made in the understanding of pneumococcal immunobiology and the prevention of invasive pneumococcal disease through vaccination. Currently, two pneumococcal vaccines are available for individuals at risk of pneumococcal disease: the 23-valent pneumococcal polysaccharide vaccine (PPV23) and the 13-valent pneumococcal protein-conjugate vaccine (PCV13). The goal of pneumococcal vaccination is to stimulate effective antipneumococcal antibody and mucosal immunity response and immunological memory. Vaccination of infants and young children with pneumococcal conjugate vaccine has led to significant decrease in nasal carriage rates and pneumococcal disease in all age groups. Recent pneumococcal vaccine indication and schedule recommendations on the basis of age and risk factors are outlined in this Focused Review. As new pneumococcal vaccine recommendations are being followed, continued efforts are needed to address the vaccine efficacy in the waning immunity of the ever-aging population, the implementation of vaccines using two different vaccines under very specific schedules and their real world clinical and cost effectiveness, and the development of next generation pneumococcal vaccines.

23-Valent Pneumococcal Polysaccharide Vaccine Uptake in the United States Air Force HIV Program

Streptococcus pneumoniae infection is a predominant cause of bacterial infection in HIV-infected individuals. However, reported rates of pneumococcal vaccination with 23-valent polysaccharide vaccine (PPV23) are variable. We evaluated uptake of PPV23 in patients diagnosed with HIV between 1996 and 2012 (n = 507) in the United States Air Force, a centralized HIV program with free access to care including vaccines and medications. A total of 411 (81.1%) patients received at least 1 PPV23 dose. The PPV23 vaccination within 1 year of diagnosis was greater for those diagnosed between 2004 and 2012 (n = 184, 86%) compared with 1996 to 2003 (n = 104, 56.5%; P < .001). For those with ≥6 years of follow-up, receipt of a second recommended PPV23 dose was greater for those diagnosed between 1996 and 2003 (n = 52, 57.8%) compared with 2004 to 2012 (n = 9, 28.1%; P = .004). Although first PPV23 vaccination was high in recent years, process improvement efforts are underway to overcome barriers and improve uptake of pneumococcal vaccines in our program.

Functional anti-polysaccharide IgG titres induced by unadjuvanted pneumococcal-conjugate vaccine when delivered by microprojection-based skin patch

Adequate access to effective and affordable vaccines is essential for the prevention of mortality due to infectious disease. Pneumonia--a consequence of Streptococcus pneumoniae infection--is the world's leading cause of death in children aged under 5 years. The development of a needle-free, thermostable pneumococcal-conjugate vaccine (PCV) could revolutionise the field by reducing cold-chain and delivery constraints. Skin patches have been used to deliver a range of vaccines, with some inducing significantly higher vaccine-specific immunogenicity than needle-injected controls in pre-clinical models, though they have yet to be used to deliver a PCV. We dry-coated a licensed PCV onto a microprojection-based patch (the Nanopatch) and delivered it to mouse skin. We analysed resulting anti-polysaccharide IgG responses. With and without adjuvant, anti-polysaccharide IgG titres induced by Nanopatch immunisation were significantly higher than dose-matched intramuscular controls. These improved responses were primarily obtained against pneumococcal serotypes 4 and 14. Importantly, capsule-specific IgG correlated with functionality in an opsonophagocytic killing assay. We demonstrate enhanced anti-PCV immunogenicity when delivered by Nanopatch over intramuscular injection. As the first study of a PCV delivered by a skin vaccination technology, this report indicates the potential for reduced costs and greater global distribution of such a vaccine.

Pneumococcal vaccination among HIV-infected adult patients in the era of combination antiretroviral therapy

HIV-infected patients remain at higher risk for pneumococcal disease than the general population despite immune reconstitution and suppression of HIV replication with combination antiretroviral therapy. Vaccination with 23-valent pneumococcal polysaccharide vaccine (PPV23) composed of T-cell-independent antigens has been recommended to reduce the risk of pneumococcal disease in HIV-infected adults. However, given the heterogeneity of study design, execution and subjects enrolled, studies examining serological responses to PPV23 yielded conflicting results and observational studies of clinical effectiveness only provided moderate evidence to support the routine use of PPV23 in HIV-infected adults. Pneumococcal conjugate vaccine (PCV), with conjugation of the capsular polysaccharide to a protein carrier, is more immunogenic than PPV23 and has been demonstrated to protect against pneumococcal disease in HIV-infected children and recurrent invasive pneumococcal disease in HIV-infected adolescents and adults. Guidelines have recently been revised to recommend that HIV-infected patients aged 19 y or older receive one dose of 13-valent pneumococcal conjugate vaccine (PCV13) followed by a booster vaccination with PPV23. In this paper, we review the studies using different vaccination strategies to improve immunogenicity among HIV-infected adult patients.

[Prevention of Streptococcus pneumoniae (pneumococcal) infections in adults]

Infections caused by Streptococcus pneumoniae (pneumococcus) are still meaning a serious health problem, about 40% of community acquired pneumonia (CAP) is due to pneumococcal bacteria in adults requiring hospitalization. The incidence and mortality rate of pneumococcal infections is increasing in the population above 50 years of age. Certain congenital and acquired immunocompromised conditions make the individual susceptible for pneumococcal infection and other chronic comorbidities should be considered as a risk factor as well, such as liver and renal diseases, COPD, diabetes mellitus. Lethality of severe pneumococcal infections with bacteraemia still remains about 12% despite adequate antimicrobial therapy in the past 60 years. Underestimation of pneumococcal infections is mainly due to the low sensitivity of diagnostic tools and underuse of bacteriological laboratory confirmation methods. 13-valent pneumococcal conjugate vaccine (PCV-13) became available recently beyond the 23-valent polysacharide vaccine (PPV-23) which has been using for a long time.The indication and proper administration of the two vaccines are based on international recommendations and vaccination guideline published by National Centre for Epidemiology (NCE):Pneumococcal vaccination is recommended for: Every person above 50 years of age. Patients of all ages with chronic diseases who are susceptible for severe pneumococcal infections: respiratory (COPD), heart, renal, liver disease, diabetes, or patients under immunsuppressive treatment. Smokers regardless of age and comorbidities. Cochlear implants, cranial-injured patients. Patients with asplenia.Recommendation for administration of the two different vaccines:Adults who have not been immunized previously against pneumococcal disease must be vaccinated with a dose of 13-valent pneumococcal conjugate vaccine first. This protection could be extended with administration of 23-valent pneumococcal polysaccharide vaccine at least two month later. Adults who have been immunized previously, but above 65 years of age, with a 23-valent polysaccharide vaccine are recommended to get one dose of conjugate vaccine at least one year later. Adults who have been immunized previously, but under 65 years of age, with a 23-valent polysaccharide vaccine are recommended to get one dose of conjugate vaccine at least one year later. After a minimal interval of two months one dose of 23-valent pneumococcal polysaccharide vaccine is recommended if at least 5 years have elapsed since their previous PPSV23 dose. Vaccination of immuncompromised patients (malignancy, transplantation, etc.) and patients with asplenia should be defined by vaccinology specialists. Pneumococcal vaccines may be administered concommitantly or any interval with other vaccines.