Immunoglobulin deficiency in patients with Streptococcus pneumoniae or Haemophilus influenzae invasive infections

Evaluation of Inborn Errors of Immunity Among Patients with Opportunistic Pulmonary Infection

This review of immunocompromised host pneumonia as the result of inborn errors of immunity (IEI) is organized by opportunistic pulmonary pathogen. The authors identify patients who warrant an evaluation for an IEI based on their clinical presentation. Their recommendations are guided by the immune defect(s) associated with each opportunistic pulmonary infection. Physicians without expertise in immunology may begin an evaluation for IEI using the guidance provided here. Comprehensive evaluation by an immunologist may also be warranted in many instances.

Searching for Immunocompromising Conditions in Low-risk Adults After Invasive Pneumococcal Disease: An Opportunity to Uncover Multiple Myeloma Early

There is a paucity of data on the prevalence of newly diagnosed immunosuppressive conditions following a first invasive pneumococcal infection (IPI) in adults considered to be at low risk for it. A total of 352 IPIs were reviewed over a 7-year period, with 39 (11.1%) ultimately analyzed. A 3.4-year follow-up period revealed that 4 patients (10.3%) had been diagnosed with immunosuppressive conditions. Of these, 3 had been diagnosed with multiple myeloma (MM). These findings indicate that in adults who experience a first IPI and are at low risk for it, MM should be strongly considered and addressed as early as possible.

Naturally acquired adaptive immunity to Streptococcus pneumoniae is impaired in rheumatoid arthritis patients

Objectives

Patients with rheumatoid arthritis (RA) have an increased susceptibility to infections, including those caused by Streptococcus pneumoniae. Why RA is associated with increased susceptibility to S. pneumoniae is poorly understood. This study aims to assess the effects of RA and B-cell depletion therapy on naturally acquired antibody responses to 289 S. pneumoniae protein antigens using a novel protein array.

Methods

IgG responses to S. pneumoniae were characterised in serum from RA patients and disease controls (myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)) using whole-cell ELISA, a flow cytometry opsonisation assay and an S. pneumoniae protein array. For the RA patients, results were compared before and after B-cell depletion therapy.

Results

Compared to a well-characterised disease control group of ME/CFS patients, RA patients had reduced antibody responses to multiple S. pneumoniae protein antigens, with significant IgG recognition of approximately half the number of antigens along with reduced median strengths of these responses. Reduction in multiple array antigen-specific responses also correlated with reduced IgG opsonisation of S. pneumoniae. Although B-cell depletion therapy with rituximab did not reduce overall IgG recognition of S. pneumoniae in the RA group, it was associated with marked disruption of pre-existing IgG repertoire to protein antigens in individual patients.

Conclusion

These data show RA is associated with major disruption of naturally acquired adaptive immunity to S. pneumoniae, which can be assessed rapidly using a protein antigen array and is likely to contribute towards the increased incidence of pneumonia in patients with RA.

Vaccinations in patients with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is characterized by immune dysfunction resulting in heightened susceptibility to infections and elevated rates of morbidity and mortality. A key strategy to mitigate infection-related complications has been immunization against common pathogens. However, the immunocompromised status of CLL patients poses challenges in eliciting an adequate humoral and cellular immune response to vaccination. Most CLL-directed therapy disproportionately impairs humoral immunity. Vaccine responsiveness also depends on the phase and type of immune response triggered by immunization. In this review, we discuss the immune dysfunction, vaccine responsiveness, and considerations for optimizing vaccine response in patients with CLL.

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.

Harnessing Nasal Immunity with IgA to Prevent Respiratory Infections

The nasal cavity is a primary checkpoint for the invasion of respiratory pathogens. Numerous pathogens, including SARS-CoV-2, S. pneumoniae, S. aureus, etc., can adhere/colonize nasal lining to trigger an infection. Secretory IgA (sIgA) serves as the first line of immune defense against foreign pathogens. sIgA facilitates clearance of pathogenic microbes by intercepting their access to epithelial receptors and mucus entrapment through immune exclusion. Elevated levels of neutralizing IgA at the mucosal surfaces are associated with a high level of protection following intranasal immunizations. This review summarizes recent advances in intranasal vaccination technology and challenges in maintaining nominal IgA levels at the mucosal surface. Overall, the review emphasizes the significance of IgA-mediated nasal immunity, which holds a tremendous potential to mount protection against respiratory pathogens.

Managing the Risk of Infection in Chronic Lymphocytic Leukemia in the Era of New Therapies

PURPOSE OF REVIEW

Patients diagnosed with CLL have an increased susceptibility to infections. Over the years, there has been a shift of the treatment arsenal to an increasing use of chemotherapy-free regimens, particularly small molecule inhibitors. These therapies have proven to be effective and have a favorable toxicity profile. Infections continue to represent a significant complication in the era of novel therapies.

RECENT FINDINGS

Recent studies continue to bring new insights into the effects of modern therapies on the immune system. Evidence supporting infection prevention strategies is scarce. We will review the available recommendations to prevent infections in patients with CLL treated with novel therapies. New CLL therapies are broadly adopted in routine practice, requiring optimization of their side effects. Timely prevention, recognition, and treatment of infections should remain an important aspect of the standard management of a patient with CLL.

Missed Opportunities? A retrospective study into adults hospitalized with invasive infection from airway pathogens

Background

Invasive disease caused by airway pathogens, including Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, and Moraxella catarrhalis, has high morbidity and mortality worldwide, with immunodeficiency being a known association with recurrent disease. The study aimed to describe the frequency of known immunodeficiency and predisposing factors in adult patients presenting with invasive infections and determine the frequency of screening for and detection of immunodeficiency.

Methods

A retrospective analysis was conducted at a large tertiary Australian health service, comprising multiple centers. Patients aged 18 years or older, in whom the above pathogens were isolated from sterile sites, were included as identified through a microbiology database, between 2015 and 2020. Using electronic medical records, patient demographics, medical history, outcomes of admission, and pathology results were captured and reviewed to address the aims.

Results

In 252 patients, S pneumoniae was the most common culprit, isolated in 73% (185/252), compared to 14.3% (36/252) and 11.5% (29/252) of infections caused by H influenzae and N meningitidis, respectively. Known diagnoses of secondary immunodeficiency were common (31% of patients). Of those presenting with invasive pneumococcal disease, 78% had at least 1 predisposing condition, though only 9 patients (6%) had previously received pneumococcal vaccination. Despite poor screening for immunodeficiency, 12 new diagnoses were made. While the commonest immunodeficiency was secondary, due to hematological and solid organ malignancies, 3 new primary immunodeficiency diagnoses were made.

Conclusions

Immunodeficiency is common in this patient population. Screening should be undertaken to ensure timely diagnosis and treatment of the underlying condition to avoid future morbidity and mortality.

Devastating Pneumococcal Arthritis of the Shoulder After Two Corticosteroid Injections

A 36-year-old man was treated with two intraarticular corticoid injections for intense pain and severely decreased range of motion of his left shoulder. After the second injection, he came back with fulminant arthritis. Microbiological examination revealed streptococcus pneumoniae. Open debridement, long-term antibiotics, and total shoulder replacement were necessary to restore acceptable shoulder function. The fulminant course with rapid destruction of the joint illustrates the risks of intraarticular corticoid injections. This case also shows that the diagnosis should be accurately made and risk factors excluded before considering injection as a treatment.

Follow-up evaluation of the immunological status of children admitted for acute cerebral nervous system infections: a retrospective study

Background

Acute Cerebral Nervous System Infections (ACNS) may cause death or severe complications even to promptly treated children. The role of the immune system in influencing the course and the outcome of meningitis has been studied but it is not yet completely understood. The aim of the research is to ascertain whether children who experienced ACNS infection had a normal immune system.

Methods

Patients under 18 years of age admitted at Bambino Gesù Children from January 2006 till June 2016 for meningitis were asked to participate to the follow-up study. The immune status was evaluated both clinically and by laboratory investigations.

Results

Most of the patients over 3 years at follow up had at least one immunological alteration at follow-up evaluation (74%). Considering ACNS infection etiology, certain pathogens were almost exclusive of patients affected by some immunological alteration, regardless of their age.

Discussion

Our preliminary results indicate that sub-clinical immunological defects may be associated to ACNS pediatric infections. Moreover, to the best of our knowledges, this is the first study correlating pathogens to immune evaluation in ACNS infections. It is, however, important to underline the high frequency of persistent immunological alterations in the analyzed patients. Further studies are needed to confirm our conclusions.

Conclusions

We recommend an immunological assessment at follow up evaluation in children who experienced an ACNS infection.

Disruption of the cpsE and endA Genes Attenuates Streptococcus pneumoniae Virulence: Towards the Development of a Live Attenuated Vaccine Candidate

The majority of deaths due to Streptococcus pneumoniae infections are in developing countries. Although polysaccharide-based pneumococcal vaccines are available, newer types of vaccines are needed to increase vaccine affordability, particularly in developing countries, and to provide broader protection across all pneumococcal serotypes. To attenuate pneumococcal virulence with the aim of engineering candidate live attenuated vaccines (LAVs), we constructed knockouts in S. pneumoniae D39 of one of the capsular biosynthetic genes, cpsE that encodes glycosyltransferase, and the endonuclease gene, endA, that had been implicated in the uptake of DNA from the environment as well as bacterial escape from neutrophil-mediated killing. The cpsE gene knockout significantly lowered peak bacterial density, BALB/c mice nasopharyngeal (NP) colonisation but increased biofilm formation when compared to the wild-type D39 strain as well as the endA gene knockout mutant. All constructed mutant strains were able to induce significantly high serum and mucosal antibody response in BALB/c mice. However, the cpsE-endA double mutant strain, designated SPEC, was able to protect mice from high dose mucosal challenge of the D39 wild-type. Furthermore, SPEC showed 23-fold attenuation of virulence compared to the wild-type. Thus, the cpsE-endA double-mutant strain could be a promising candidate for further development of a LAV for S. pneumoniae.

Prevalence of Hypogammaglobulinemia in Adult Invasive Pneumococcal Disease

Background

Patients with humoral immune deficiency are susceptible to invasive pneumococcal disease (IPD). This study estimates the prevalence of underlying hypogammaglobulinemia in admitted IPD cases and examines whether IPD cases had received preventative treatment.

Methods

All adult IPD cases (Streptococcus pneumoniae in blood or cerebrospinal fluid) admitted to The Ottawa Hospital (TOH) from January 2013 to December 2015 were identified through the Eastern Ontario Regional Laboratory. Documented clinical demographics, S. pneumoniae serotype, serum immunoglobulins measured previously or in convalescence, and vaccination status of the cases were collected retrospectively for descriptive analyses.

Results

There were 134 IPD in 133 patients (47.4% male; mean age 63, standard deviation [SD] = 15.6 years) during a 3-year observation period. All-cause mortality rate was 22.6% over a mean follow-up time of 362, SD = 345 days. Fifty-seven patients (42.9%) had serum immunoglobulin levels measured. Eighteen were either found to have hypogammaglobulinemia in convalescence (8/18) or previously known to have hypogammaglobulinemia (10/18). None of the known hypogammaglobulinemic patients had received antibiotic prophylaxis and/or immunoglobulin replacement therapy within 4 months prior to IPD. The high and low estimates of prevalence of hypogammaglobulinemia were 31.6% (of all measured) and 13.5% (of all cases). Among 18 patients with hematological malignancies in our cohort, 13 had hypogammaglobulinemia. Many isolates were vaccine serotypes; however, only 8 had documented previous pneumococcal vaccination.

Conclusions

IPD has high mortality, and hypogammaglobulinemia was present in at least 13.5% of IPD cases. Secondary hypogammaglobulinemia is especially common in cases with hematological malignancy and IPD.

Measurement of Humoral Immune Competence and the Risk of Sinopulmonary Infection in a Cohort of Kidney Transplant Recipients

PURPOSE

The aim of this study was to determine if measurement of B cell protective immunity was associated with susceptibility to sinopulmonary infection in kidney transplant recipients.

METHODS AND MATERIALS

A prospective cohort of 168 patients with stable graft function (median 4.1 years) underwent assessment of B-lymphocyte antigen CD19 (CD19⁺) cell number, immunoglobulin G concentration, and seroresponses to influenza vaccination upon study entry. Patients received a single dose of a trivalent, seasonal influenza vaccine.

RESULTS

After 2 years follow-up, 31 patients (18%) developed sinopulmonary infection. CD19⁺ cell number was strongly associated with future sinopulmonary infection. A higher proportion of patients with CD19⁺ cell counts below the fifth percentile for controls developed sinopulmonary infections than those above the fifth percentile, 30% (23 of 77 patients) compared with 9% (7 of 79 patients; P = .001). There was a trend toward a higher proportion of patients with reduced immunoglobulin G concentrations developing infections than in the normal range for controls, 29% (14 of 48 patients) compared with 15% (16 of 108 patients; P = .060). Influenza vaccination seroresponses were poor in patients and controls such that they could not be used to identify a subgroup of patients at high risk for the development of severe pulmonary infection.

CONCLUSIONS

Monitoring B-cell numbers represents a simple, inexpensive means of stratifying transplant recipients' risk of sinopulmonary infection.

Can immune biomarkers predict infections in solid organ transplant recipients? A review of current evidence

Despite improvements in graft survival, solid organ transplantation is still associated with considerable infection induced morbidity and mortality. If we were able to show that serious infection risk was associated with excessive suppression of immune capacity, we would be justified in "personalizing" the extent of immunosuppression by carefully monitored reduction to see if we can improve immune compromize without increasing the risk of rejection. Reliable biomarkers are needed to identify this patients at an increased risk of infection. This review focuses on the currently available evidence in solid organ transplant recipients for immune non-pathogen specific biomarkers to predict severe infections with the susceptibility to particular pathogens according to the component of the immune system that is suppressed. This review is categorized into immune biomarkers representative of the humoral, cellular, phagocytic, natural killer cell and complement system. Biomarkers humoral and cellular systems of the that have demonstrated an association with infections include immunoglobulins, lymphocyte number, lymphocyte subsets, intracellular concentrations of adenosine triphosphate in stimulated CD4⁺ cells and soluble CD30. Biomarkers of the innate immune system that have demonstrated an association with infections include natural killer cell numbers, complement and mannose binding lectin. Emerging evidence shows that quantification of viral nucleic acid (such as Epstein Barr Virus) can act as a biomarker to predict all-cause infections. Studies that show the most promise are those in which several immune biomarkers are assessed in combination. Ongoing research is required to validate non-pathogen specific immune biomarkers in multi-centre studies using standardized study designs.

Pneumolysin as a potential therapeutic target in severe pneumococcal disease

Acute pulmonary and cardiac injury remain significant causes of morbidity and mortality in those afflicted with severe pneumococcal disease, with the risk for early mortality often persisting several years beyond clinical recovery. Although remaining to be firmly established in the clinical setting, a considerable body of evidence, mostly derived from murine models of experimental infection, has implicated the pneumococcal, cholesterol-binding, pore-forming toxin, pneumolysin (Ply), in the pathogenesis of lung and myocardial dysfunction. Topics covered in this review include the burden of pneumococcal disease, risk factors, virulence determinants of the pneumococcus, complications of severe disease, antibiotic and adjuvant therapies, as well as the structure of Ply and the role of the toxin in disease pathogenesis. Given the increasing recognition of the clinical potential of Ply-neutralisation strategies, the remaining sections of the review are focused on updates of the types, benefits and limitations of currently available therapies which may attenuate, directly and/or indirectly, the injurious actions of Ply. These include recently described experimental therapies such as various phytochemicals and lipids, and a second group of more conventional agents the members of which remain the subject of ongoing clinical evaluation. This latter group, which is covered more extensively, encompasses macrolides, statins, corticosteroids, and platelet-targeted therapies, particularly aspirin.

Disseminated adenovirus infection causing severe ARDS

A previously healthy young man with a rare genetic condition presented with severe acute respiratory distress syndrome secondary to pneumonia with septic shock. He did not improve with conventional therapy for his known causal organism thus prompting further workup. He was found to be profoundly immunosuppressed raising our suspicion for atypical organisms. A bronchoalveolar lavage sample was positive via PCR for adenovirus which we suspect exacerbated a pre-existing bacterial pneumonia and led to a severe and non-responsive respiratory failure. His serum adenovirus load was markedly elevated. Treatment was started once the diagnosis of disseminated adenovirus infection was made; however, at that time patient was suffering from refractory hypoxaemia, respiratory acidosis, right heart failure and septic shock. Despite maximal supportive measures our patient ultimately expired over the course of 6 days.

Methods of rapid diagnosis for the etiology of meningitis in adults

Infectious meningitis may be due to bacterial, mycobacterial, fungal or viral agents. Diagnosis of meningitis must take into account numerous items of patient history and symptomatology along with regional epidemiology and basic cerebrospinal fluid testing (protein, etc.) to allow the clinician to stratify the likelihood of etiology possibilities and rationally select additional diagnostic tests. Culture is the mainstay for diagnosis in many cases, but technology is evolving to provide more rapid, reliable diagnosis. The cryptococcal antigen lateral flow assay (Immuno-Mycologics) has revolutionized diagnosis of cryptococcosis and automated nucleic acid amplification assays hold promise for improving diagnosis of bacterial and mycobacterial meningitis. This review will focus on a holistic approach to diagnosis of meningitis as well as recent technological advances.

Should mild hypogammaglobulinemia be managed as severe hypogammaglobulinemia? A study of 389 patients with secondary hypogammaglobulinemia

BACKGROUND

Although secondary hypogammaglobulinemia is more frequent than primary hypogammaglobulinemia, its etiology and management are poorly described, particularly for mild hypogammaglobulinemia.

METHODS

This retrospective observational study included all adult patients with a gammaglobulin level <6.4g/L on serum electrophoresis identified at Dijon teaching hospital between April and September 2012. Clinico-biological features, etiologies and infectious complications were collected at inclusion and compared between group 1 (gammaglobulin <5g/L, severe hypogammaglobulinemia), and group 2 (gammaglobulin <6.4 and ≥5g/L, mild hypogammaglobulinemia).

RESULTS

Among the 4011 serum electrophoreses, 570 samples from 389 patients had gammaglobulin levels below 6.4g/L: 156 (40%) in group 1 and 233 (60%) in group 2. Mean age±SD was 67 (15) years, and sex ratio was 1.04 (M/F) with no difference between the two groups. An etiology was identified in 79% and 58% of patients in groups 1 and 2, respectively (p<0.0001). The main etiologies were similar in both groups and included malignant hemopathy treated with cytostatic agents (n=129, 33%), smoldering or newly-diagnosed hemopathy without treatment (n=49, 13%) and immunosuppressive treatment (n=91, 23%). The incidence of hypogammaglobulinemia-related infections was 22/100/year, with no significant difference between the two groups (p=0.17). Vaccination coverage against pneumococcus was 33%, and higher in group 1 (46% vs. 24%; p<0.0001). When no cause was known at inclusion, an etiology was discovered in 22/130 patients (17%), 11 in each group.

CONCLUSIONS

Though mild hypogammaglobulinemia does not meet the classical criteria for hypogammaglobulinemia (<5g/L), the etiology and infectious risk are similar. It therefore requires investigation and vaccination.