Specific Polysaccharide Antibody Deficiency Revealed by Severe Bacterial Infections in Adulthood: A Report on 11 Cases

Monogenic Inborn Errors of Immunity with impaired IgG response to polysaccharide antigens but normal IgG levels and normal IgG response to protein antigens

In patients with severe and recurrent infections, minimal diagnostic workup to test for Inborn Errors of Immunity (IEI) includes a full blood count, IgG, IgA and IgM. Vaccine antibodies against tetanus toxoid are also frequently measured, whereas testing for anti-polysaccharide IgG antibodies and IgG subclasses is not routinely performed by primary care physicians. This basic approach may cause a significant delay in diagnosing monogenic IEI that can present with an impaired IgG response to polysaccharide antigens with or without IgG subclass deficiency at an early stage. Our article reviews genetically defined IEI, that may initially present with an impaired IgG response to polysaccharide antigens, but normal or only slightly decreased IgG levels and normal responses to protein or conjugate vaccine antigens. We summarize clinical, genetic, and immunological findings characteristic for these IEI. This review may help clinicians to identify patients that require extended immunologic and genetic evaluations despite unremarkable basic immunologic findings. We recommend the inclusion of anti-polysaccharide IgG antibodies as part of the initial routine work-up for possible IEI.

Inborn Errors of Immunity in Children With Invasive Pneumococcal Disease: A Multicenter Prospective Study

BACKGROUND

In settings with universal conjugate pneumococcal vaccination, invasive pneumococcal disease (IPD) can be a marker of an underlying inborn error of immunity. The aim of this study was to determine the prevalence and characterize the types of immunodeficiencies in children presenting with IPD.

METHODS

Multicenter prospective audit following the introduction of routinely recommended immunological screening in children presenting with IPD. The minimum immunological evaluation comprised a full blood examination and film, serum immunoglobulins (IgG, IgA and IgM), complement levels and function. Included participants were children in whom Streptococcus pneumoniae was isolated from a normally sterile site (cerebrospinal fluid, pleura, peritoneum and synovium). If isolated from blood, features of sepsis needed to be present. Children with predisposing factors for IPD (nephrotic syndrome, anatomical defect or malignancy) were excluded.

RESULTS

Overall, there were 379 episodes of IPD of which 313 (83%) were eligible for inclusion and 143/313 (46%) had an immunologic evaluation. Of these, 17/143 (12%) were diagnosed with a clinically significant abnormality: hypogammaglobulinemia (n = 4), IgA deficiency (n = 3), common variable immunodeficiency (n = 2), asplenia (n = 2), specific antibody deficiency (n = 2), incontinentia pigmenti with immunologic dysfunction (n = 1), alternative complement deficiency (n = 1), complement factor H deficiency (n = 1) and congenital disorder of glycosylation (n = 1). The number needed to investigate to identify 1 child presenting with IPD with an immunologic abnormality was 7 for children under 2 years and 9 for those 2 years old and over.

CONCLUSIONS

This study supports the routine immune evaluation of children presenting with IPD of any age, with consideration of referral to a pediatric immunologist.

High Frequency of Specific Polysaccharide Antibody Deficiency in Adults With Unexplained, Recurrent and/or Severe Infections With Encapsulated Bacteria

BACKGROUND

Primary immunodeficiencies (PIDs) in adults are mainly revealed by recurrent and/or severe bacterial infections. The objective of this study was to evaluate a systematic research strategy of PIDs in adults with unexplained bacterial infections, with a special focus on specific polysaccharide antibody deficiency (SPAD).

METHODS

In this prospective multicenter study, inclusion criteria were recurrent benign upper and lower respiratory tract infections (RTIs) for at least two years (group 1), at least one upper or lower RTI requiring hospitalization (group 2), and/or at least one invasive infection documented with encapsulated bacteria (group 3). Main exclusion criteria were all local and general conditions that could explain infections. If no PID diagnosis was made, response to polysaccharide antigens was assessed using a pneumococcal polysaccharide vaccine.

RESULTS

From March 2015 to March 2020, 118 patients were included (37 males, median age of 41 years): 73, 17, and 28 in groups 1, 2, and 3, respectively. Forty-seven PIDs were diagnosed, giving an estimated frequency of 39.8% (95% confidence interval [CI] [30.4, 48.8]). SPAD was the most frequent diagnosis by far (n = 37/47, 78.7%), and was made in 23, 5, and 9 patients from groups 1 to 3, respectively. All SPAD patients received conjugate vaccines and, according to their infectious history, were on surveillance or treated with preventive antibiotics (n = 6) and/or with immunoglobulins replacement therapy (n = 10), the latter being dramatically efficient in all cases.

CONCLUSIONS

Considering its high prevalence among adults with unexplained recurrent and/or severe bacterial infections, SPAD should be screened in those patients.

CLINICAL TRIALS REGISTRATION

NCT02972281.

Specific antibody deficiency to pneumococcal polysaccharide in a young adult with recurrent respiratory infections: a case report

Specific antibody deficiency against pneumococcal serotypes was detected in a patient with recurrent episodes of fever. A 21-year-old man presented with a two-month history of recurrent episodes of fever and shaking chills. He was diagnosed with recurrent episodes of pneumonia caused by Streptococcus pneumoniae serotype 19A and treated with amoxicillin. Serotype-specific antibodies were not produced against most of the serotypes, which were consistent with moderate specific antibody deficiency. After pneumococcal 13-valent conjugate vaccination and pneumococcal polysaccharide vaccination, he adequately responded to the infecting serotype with an antibody titer of 1.1 µg/mL. There were eventually no recurrent episodes of fever with pneumonia.

Characteristics of Pediatric Recurrent Bacterial Meningitis in Beijing Children's Hospital, 2006-2019

BACKGROUND

Few data on recurrent bacterial meningitis (RBM) in children are available. Here, we estimated the frequency of RBM in children and investigated the predisposing conditions, etiology, and clinical characteristics of RBM in children.

METHODS

Cases of RBM in the Beijing Children's Hospital medical record database between January 2006 and December 2019 were collected.

RESULTS

In total, 1905 children with bacterial meningitis (BM) were documented in the Beijing Children's Hospital medical record database. A total of 43 patients had RBM. The rate of RBM in children was 2.3% (43/1905). Forty (93.0%) patients had predisposing conditions, including 15 (34.9%) cases of inner ear malformations, 5 (11.6%) cases of dermal sinus tracts, 9 (20.9%) cases of head injury, 5 (11.6%) cases of congenital cranial meningocele, 3 (7.0%) cases of congenital skull base defects, 3 (7.0%) cases of immunodeficiency, and other 3 (7.0%) cases of unknown reason. Among all the 121 BM episodes, a total of 64 episodes were etiologically confirmed BM and the other 57 episodes were probable BM. Streptococcus pneumoniae (n = 52) was accounted for 81.3% of confirmed BM episodes. Thirty-four of the 37 patients with congenital or acquired anatomical defects were available to follow up after surgeries, and all of them had no BM after surgeries. Three patients with antibody deficiencies got intravenous immunoglobulin therapy and they did not suffer BM anymore.

CONCLUSIONS

RBM is rare in children. The majority of children with RBM had predisposing conditions including congenital/acquired anatomical defects and immunodeficiency. Interventions should be implemented to solve the underlying conditions to avoid RBM.

More than Meets the Eye: Bacteremic Pneumococcal Pneumonia as the Initial Presentation of Multiple Myeloma

Patient: Male, 60-year-old

Final Diagnosis: Streptococcus pneumoniae bacteremia • multiple myeloma

Symptoms: Chills • cough • fever

Medication: —

Clinical Procedure: Bone marrow biopsy • CT scan • serology

Specialty: Hematology • Infectious Diseases • General and Internal Medicine

Isolating polysaccharide IgG pneumococcal antibody responses by pre-adsorption of conjugate vaccine serotypes: A modified approach for the conjugate vaccine era

BACKGROUND

Assessment of pure polysaccharide response to the 23-valent pneumococcal polysaccharide vaccine (PPV23) can be biased by previous exposure to the conjugate vaccine (PCV). We applied pre-analytical modification to the existing ELISA by pre-incubating serum with PCV.

METHODS

PCV-adsorbed and non-adsorbed sera were prepared before measuring the concentration of anti-pneumococcal capsular polysaccharide (PCP) IgG antibodies by the whole pneumococcal ELISA. Paired pre and post-pneumococcal vaccination sera from 73 subjects were analyzed and the baseline anti-PCP IgG for each sample was subtracted from the post-vaccination value to measure vaccine responses. Absolute change in titers and fold changes were then compared between both methods.

RESULTS

In the PCV-vaccinated group (n = 28), pre-adsorption with PCV significantly reduced the vaccine responses compared to non-adsorbed sera [median increase in anti-PCP titers: 27.55 mg/l and 45.98 mg/l, respectively]. In addition, the median fold change dropped significantly from 3.026 to 2.313. In PPV23-vaccinated immunocompetent subjects (n = 28) there was a significant difference in anti-PCP responses with PCV adsorption [median values: 73.71 mg/l without and 51.04 mg/l with adsorption]. All the antibody deficiency patients (n = 17) displayed poor PPV23 responses. Although PPV23 responsiveness was not statistically different between both methods, we have observed a trend for lower anti-PCP IgG titers in PCV-adsorbed sera compared to non-adsorbed ones. Serotype-specific IgG analysis using a multiplexed bead-based immunoassay performed on 10 paired samples confirmed that the adsorption observed is specific to PCV serotypes.

CONCLUSION

Pre-analytical modification to the conventional ELISA by removing the PCV-specific serotypes may differentiate true polysaccharide response from recall response induced by previous PCV vaccination.

Interest of immunodeficiency screening in adult after admission in medical intensive care unit for severe infection, a retrospective and a prospective study: the Intensive Care Unit and Primary and Secondary Immunodeficiency (ICUSPID) study

BACKGROUND

Primary immunodeficiency (PID) in adults is rare and mostly revealed by infections.

MATERIAL AND METHODS

Adults without predisposing factors who were admitted to an intensive care unit (ICU) for infection were screened for PID.

RESULTS

Six PID cases were diagnosed, mostly revealed by encapsulated bacterial infections.

CONCLUSION

Investigation of PID after ICU discharge should be considered to improve early detection.

Capsule and fimbriae modulate the invasion of Haemophilus influenzae in a human blood-cerebrospinal fluid barrier model

The Gram-negative bacterium Haemophilus influenzae (H. influenzae) can commensally colonize the upper respiratory tract, but also cause life threatening disease including epiglottitis, sepsis and meningitis. The H. influenzae capsule protects the bacteria against both phagocytosis and opsonization. Encapsulated H. influenzae strains are classified into serotypes ranging from a to f dependent on their distinct polysaccharide capsule. Due to the implementation of vaccination the incidence of invasive H. influenzae type b (Hib) infections has strongly decreased and infections with other capsulated types, including H. influenzae type f (Hif), are emerging. The pathogenesis of H. influenzae meningitis is not clarified. To enter the central nervous system (CNS) the bacteria generally have to cross either the blood-brain barrier (BBB) or the blood-cerebrospinal fluid barrier (BSCFB). Using a cell culture model of the BCSFB based on human choroid plexus papilloma (HIBCPP) cells and different H. influenzae strains we investigated whether Hib and Hif invade the cells, and if invasion differs between encapsulated vs. capsular-deficient and fimbriated vs. non-fimbriated variants. We find that Hib can adhere to and invade into HIBCPP cells. Invasion occurs in a strongly polar fashion, since the bacteria enter the cells preferentially from the basolateral "blood "side. Fimbriae and capsule attenuate invasion into choroid plexus (CP) epithelial cells, and capsulation can influence the bacterial distribution pattern. Finally, analysis of clinical Hib and Hif isolates confirms the detected invasive properties of H. influenzae. Our data point to roles of capsule and fimbriae during invasion of CP epithelial cells.

Immunogenicity and persistence of a prime-boost re-vaccination strategy for pneumococcal vaccines in patients with rheumatoid arthritis

OBJECTIVES

Patients with rheumatoid arthritis (RA) are at an increased risk of Pneumococcal infections. Immunogenicity and persistence of a prime-boost revaccination strategy using 13-valent/23-valent anti-pneumococcal vaccines was evaluated in patients with RA treated by Methotrexate (MTX) and anti-TNF.

METHOD

Twenty-four patients with RA received one dose of PCV13 (Prevenar13®; Pfizer) followed two months later by one dose of PPV23 (Pneumovax®, Merck). Concentrations of IgG specific for 7 serotypes common to both vaccines and 3 uncommon serotypes, included only in the PPV23 were measured by ELISA and Opsonophagocytic Assay (OPA) at baseline and after 4, 12 and 24 months post-vaccine.

RESULTS

Similar percentages of protection were found at 4 months (63% vs. 55%), 12 months (54% vs. 50%) and 24 months (52% vs. 55%) for the 7 common and 3 uncommon serotypes when antibody titers were assayed by ELISA. Based on functional antibody measurements by OPA, a decrease of protected patients was observed 24 months after vaccine with only 19% of patients protected compared to 29% at baseline.

CONCLUSION

Although the combined pneumococcal revaccination strategy induces good protection in the short term in RA patients, this protection does not persist beyond two years with levels of functional antibody decreasing below pre-vaccine levels. We did not observe a higher efficacy of the conjugate vaccine compared to the polysaccharide vaccine. Our results clearly question the advantage of the prime-boost strategy as it highlight the possible hyporesponse induced by PPV23 against the immune response elicited by the primo-injection of the PCV13 vaccine.

Value of the Overall Pneumococcal Polysaccharide Response in the Diagnosis of Primary Humoral Immunodeficiencies

Background

An overall response assay [OVA, based on a 23-valent pneumococcal polysaccharide vaccine (PPV23)] is widely used to screen for anti-pneumococcal antibodies. Given the heterogeneity of response from one polysaccharide (PS) to another, a World Health Organization-standardized serotype-specific enzyme-linked immunosorbent assay (SSA) is considered to be the only reliable method for testing anti-PS antibody responses in individuals with suspected primary immunodeficiencies (PIDs).

Objective

To evaluate the OVA relative to the reference SSA.

Methods

Serum samples of adult patients referred for a suspected PID were collected before and then 4–8 weeks after immunization with PPV23. The anti-pneumococcal response was systematically assessed with an SSA (7–16 serotypes) and interpreted according to the American Academy of Asthma, Allergy and Immunology’s current guidelines. We used receiver operating characteristic curves and agreement indices to assess the OVA’s diagnostic value in a first cohort. In order to validate these findings, a second (validation) cohort was then prospectively included.

Results

Sixty-two adult patients were included, and 42 (67.7%) were defined as poor responders according to the SSA. Only the post-immunization titer in the OVA was able to correctly identify poor responders; a titer below 110 mg/L gave a positive predictive value of 100% [identifying 24 (57.1%) of the 42 poor responders], and similar levels of diagnostic performance were observed in the validation cohort. The pre-vaccination antibody titer, the post/pre-vaccination antibody titer ratio and a post-vaccination titer above 110 mg/L in the OVA were not predictive of the response in the SSA.

Conclusion

A post-vaccination antibody titer below 110 mg/L in the OVA was constantly associated with a poor PPV23 response using the SSA. In all other cases, SSA is the only reliable method for assessing diagnostic vaccination with PPV23.