Reply to Bouva et al. Comment on "Dijkstra et al. A False-Negative Newborn Screen for Tyrosinemia Type 1-Need for Re-Evaluation of Newborn Screening with Succinylacetone. Int. J. Neonatal Screen. 2023, 9, 66".

We thank the authors for their comments [...].

Clinical exome sequencing data from patients with inborn errors of immunity: Cohort level diagnostic yield and the benefit of systematic reanalysis.

While next generation sequencing has expanded the scientific understanding of Inborn Errors of Immunity (IEI), the clinical use and re-use of exome sequencing is still emerging. We revisited clinical exome data from 1300 IEI patients using an updated in silico IEI gene panel. Variants were classified and curated through expert review. The molecular diagnostic yield after standard exome analysis was 11.8 %. Through systematic reanalysis, we identified variants of interest in 5.2 % of undiagnosed patients, with 76.7 % being (candidate) disease-causing, providing a (candidate) diagnosis in 15.2 % of our cohort. We find a 1.7 percentage point increase in conclusive molecular diagnoses. We find a high degree of actionability in patients with a genetic diagnosis (76.4 %). Despite the modest absolute diagnostic gain, these data support the benefit of iterative exome reanalysis in IEI patients, conveying the notion that our current understanding of genes and variants involved in IEI is by far not saturated.

A False-Negative Newborn Screen for Tyrosinemia Type 1-Need for Re-Evaluation of Newborn Screening with Succinylacetone.

Undiagnosed and untreated tyrosinemia type 1 (TT1) individuals carry a significant risk for developing liver fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Elevated succinylacetone (SA) is pathognomonic for TT1 and therefore often used as marker for TT1 newborn screening (NBS). While SA was long considered to be elevated in every TT1 patient, here we present a recent false-negative SA TT1 screen. A nine-year-old boy presented with HCC in a cirrhotic liver. Additional tests for the underlying cause unexpectedly revealed TT1. Nine years prior, the patient was screened for TT1 via SA NBS with a negative result: SA 1.08 µmol/L, NBS cut-off 1.20 µmol/L. To our knowledge, this report is the first to describe a false-negative result from the TT1 NBS using SA. False-negative TT1 NBS results may be caused by milder TT1 variants with lower SA excretion. Such patients are more likely to be missed in NBS programs and can be asymptomatic for years. Based on our case, we advise TT1 to be considered in patients with otherwise unexplained liver pathology, including fibrosis, cirrhosis and HCC, despite a previous negative TT1 NBS status. Moreover, because the NBS SA concentration of this patient fell below the Dutch cut-off value (1.20 µmol/L at that time), as well as below the range of cut-off values used in other countries (1.29-10 µmol/L), it is likely that false-negative screening results for TT1 may also be occurring internationally. This underscores the need to re-evaluate TT1 SA NBS programs.

Severe Immune-Related Enteritis after In Utero Exposure to Pembrolizumab.

Immune checkpoint blockade has become standard treatment for many types of cancer. Such therapy is indicated most often in patients with advanced or metastatic disease but has been increasingly used as adjuvant therapy in those with early-stage disease. Adverse events include immune-related organ inflammation resembling autoimmune diseases. We describe a case of severe immune-related gastroenterocolitis in a 4-month-old infant who presented with intractable diarrhea and failure to thrive after in utero exposure to pembrolizumab. Known causes of the symptoms were ruled out, and the diagnosis of pembrolizumab-induced immune-related gastroenterocolitis was supported by the results of histopathological assays, immunophenotyping, and analysis of the level of antibodies against programmed cell death protein 1 (PD-1). The infant's condition was successfully treated with prednisolone and infliximab.

[Tuberculosis of the central nervous system]. / Tuberculose van het centraal zenuwstelsel.

In the Netherlands, 600 patients are diagnosed with tuberculosis annually, especially refugees and migrants. After arrival in the Netherlands, they are screened with a chest X-ray. However, 45% of patients present with extrapulmonary tuberculosis. We present a case of a 9 year old boy from Eritrea with tuberculosis of the central nervous system. When central nervous system tuberculosis is suspected, further diagnostic testing should be done and therapy started as soon as possible to prevent mortality and morbidity.

Success rates of MRSA decolonization and factors associated with failure.

BACKGROUND: We evaluated the success rate of MRSA decolonization directly after treatment and after one year in patients who were treated at the outpatient MRSA clinic of a large university medical centre to identify potential contributing factors to treatment success and failure. METHODS: Data from November 1, 2013 to August 1, 2020 were used. Only patients who had undergone complete MRSA decolonization were included. Risk factors for MRSA treatment failure were identified using a multivariable logistic regression model. RESULTS: In total, 127 MRSA carriers were included: 7 had uncomplicated carriage, 91 had complicated carriage, and 29 patients had complicated carriage in combination with an infection. In complicated carriers and complicated carriers with an infection final treatment was successful in 75.0%. Risk factors for initial treatment failure included having one or more comorbidities and not testing the household members. Risk factors for final treatment failure were living in a refugee centre, being of younger age (0-17 years), and having one or more comorbidities. CONCLUSIONS: The results of this study indicate that patients with a refugee status and children treated at the paediatric clinic have a higher risk of MRSA decolonisation treatment failure. For this reason, it might be useful to revise decolonization strategies for these subgroups and to refer these patients to specialized outpatient clinics in order to achieve higher treatment success rates.

Non-invasive diagnostics of pathogenic bacteria using a breath sampler in children with cystic fibrosis.

Cystic fibrosis (CF) is a common autosomal recessive disease causing thick, viscous secretions leading to pulmonary infections with pathogenic bacteria. As part of routine patient care, colonization and infection with these bacteria is monitored with cough swab or sputum cultures and sometimes bronchoalveolar lavage. In this cross-sectional proof-of-concept study in a cohort of CF patients we collected swabs or sputa and exhaled breath samples with the modular breath sampler (MBS), a newly developed two-way non-rebreathing sampling device. Pathogen specific polymerase chain reactions (PCRs) were performed on the MBS samples and compared with the results obtained with conventional diagnostics (i.e. culturing of swabs and sputa). A control group of stable asthma patients was used as negative control for the MBS measurements. The pathogens detected using MBS and conventional culturing differed:S. aureuswas found more often in swab or sputum samples whereasPseudomonas aeruginosaandS. pneumoniaewere found more often in MBS samples. We hypothesize that this is due to sampling of different compartments, MBS samples are derived from the lower respiratory tract while cultures from cough swabs and sputa are dominated by pathogens residing in the upper respiratory tract. Another important difference is the readout, i.e. culture versus PCR. The majority of CF patients in whomP. aeruginosawas found did not have recent positive cultures suggesting higher sensitivity of MBS-based than conventional diagnostics. The majority of parents/patients found the MBS easy to use and less of a burden than respiratory sampling.

Raltegravir-based Postnatal HIV Prophylaxis Therapy in a Neonate After in Utero Dolutegravir Exposure.

We present a case report of a neonate receiving raltegravir-based postnatal HIV prophylaxis after in utero dolutegravir exposure. High levels of raltegravir and dolutegravir can potentially cause bilirubin toxicity as they compete for albumin binding and follow the same metabolic pathway through UGT1A1. This case suggests delaying initiation of raltegravir-based postnatal prophylaxis by 24-48 hours after in utero dolutegravir exposure.

Clinical characteristics and an evaluation of predictors for a favourable outcome of Mycobacterium abscessus otomastoiditis: a systematic review and meta-analysis of individual participant data.

BACKGROUND: Otomastoiditis caused by Mycobacterium abscessus is rare, but its incidence has increased over the past decades and its optimal treatment remains unknown. This study aims to summarise the clinical and therapeutic features and find characteristics of patients with M. abscessus otomastoiditis associated with favourable treatment outcomes. METHODS: We searched MEDLINE, Embase and Web of Science to identify studies including patients with M. abscessus otomastoiditis. A 1-stage individual patient data (IPD) meta-analysis was conducted. A 2-level mixed-effects linear regression model was provided for antimycobacterial treatment duration. RESULTS: Twenty-three studies reported a total of 85 patients. Children possess a unique clinical profile including a history of ear infections, tympanostomy tube placement and antibiotic treatment. Antimycobacterial treatment was administered for 26 (interquartile range [IQR]: 15-35) weeks. Macrolides were prescribed in 98.8% of the cases. Surgery was performed in 80.5% of the cases, of which, 47.1% required revision surgery. Otalgia was a significant predictor (ß = 9.3; P = .049) of antimycobacterial treatment duration. CONCLUSIONS: Mastoid surgery (regularly requiring revision) and a multidrug regimen for a minimum of 6 months, including a minimum of 3 active agents, are most often needed to attain cure. The presence of otalgia significantly extends the treatment duration of M. abscessus otomastoiditis.

Simple Measurement of IgA Predicts Immunity and Mortality in Ataxia-Telangiectasia.

Patients with ataxia-telangiectasia (A-T) suffer from progressive cerebellar ataxia, immunodeficiency, respiratory failure, and cancer susceptibility. From a clinical point of view, A-T patients with IgA deficiency show more symptoms and may have a poorer prognosis. In this study, we analyzed mortality and immunity data of 659 A-T patients with regard to IgA deficiency collected from the European Society for Immunodeficiencies (ESID) registry and from 66 patients with classical A-T who attended at the Frankfurt Goethe-University between 2012 and 2018. We studied peripheral B- and T-cell subsets and T-cell repertoire of the Frankfurt cohort and survival rates of all A-T patients in the ESID registry. Patients with A-T have significant alterations in their lymphocyte phenotypes. All subsets (CD3, CD4, CD8, CD19, CD4/CD45RA, and CD8/CD45RA) were significantly diminished compared to standard values. Patients with IgA deficiency (n = 35) had significantly lower lymphocyte counts compared to A-T patients without IgA deficiency (n = 31) due to a further decrease of naïve CD4 T-cells, central memory CD4 cells, and regulatory T-cells. Although both patient groups showed affected TCR-ß repertoires compared to controls, no differences could be detected between patients with and without IgA deficiency. Overall survival of patients with IgA deficiency was significantly diminished. For the first time, our data show that patients with IgA deficiency have significantly lower lymphocyte counts and subsets, which are accompanied with reduced survival, compared to A-T patients without IgA deficiency. IgA, a simple surrogate marker, is indicating the poorest prognosis for classical A-T patients. Both non-interventional clinical trials were registered at clinicaltrials.gov 2012 (Susceptibility to infections in ataxia-telangiectasia; NCT02345135) and 2017 (Susceptibility to Infections, tumor risk and liver disease in patients with ataxia-telangiectasia; NCT03357978).

Complement factor D haplodeficiency is associated with a reduced complement activation speed and diminished bacterial killing.

OBJECTIVES: Complete deficiency of alternative pathway (AP) complement factors, explained by homozygous mutations, is a well-known risk factor for invasive bacterial infections; however, this is less obvious for heterozygous mutations. We describe two siblings with a heterozygous NM_001928.3(CFD):c.125C>A p.(Ser42*) mutation in the complement factor D (fD) gene having a history of recurrent bacterial infections. We determined the effect of heterozygous fD deficiency on AP complement activity. METHODS: We determined the effect of fD levels on complement activation as measured by AP activity, complement C3 binding to the bacterial surface of Neisseria meningitidis (Nm), Streptococcus pneumoniae (Sp) and non-typeable Haemophilus influenzae (NTHi), and complement-mediated killing of Nm and NTHi. In addition, we measured the effect of vaccination of complement C3 binding to the bacterial surface and killing of Nm. RESULTS: Reconstitution of fD-deficient serum with fD increased AP activity in a dose- and time-dependent way. Reconstitution of patient serum with fD to normal levels increased complement C3 binding to Sp, Nm and NTHi, as well as complement-mediated killing of Nm and NTHi. Vaccination increased complement C3 binding and resulted in complete killing of Nm without fD reconstitution. CONCLUSION: We conclude that low fD serum levels (< 0.5 µg mL-1) lead to a reduced speed of complement activation, which results in diminished bacterial killing, consistent with recurrent bacterial infections observed in our index patients. Specific antibodies induced by vaccination are able to overcome the diminished bacterial killing capacity in patients with low fD levels.

Respiratory Tract Infection Management and Antibiotic Prescription in Children: A Unique Study Comparing Three Levels of Healthcare in The Netherlands.

BACKGROUND: Respiratory tract infections (RTIs) are common in children with febrile illness visiting the general practitioner (GP) or emergency department. We studied the management of children with fever and RTI at 3 different levels of healthcare in The Netherlands, focusing on antibiotic prescription. METHODS: This prospective observational study is part of the Management and Outcome of Febrile children in Europe study. Data were used from face-to-face patient contacts of children with febrile illness in three healthcare settings in Nijmegen, The Netherlands during 2017. These settings were primary (GP), secondary (general hospital) and tertiary care (university hospital). RESULTS: Of 892 cases with RTI without complex comorbidities, overall antibiotic prescription rates were 29% with no differences between the 3 levels of healthcare, leading to an absolute number of 5031 prescriptions per 100,000 children per year in primary care compared with 146 in secondary and tertiary care combined. The prescription rate in otitis media was similar in all levels: 60%. In cases with lower RTI who received nebulizations prescription rates varied between 19% and 55%. CONCLUSIONS: Antibiotic prescription rates for RTIs in children were comparable between the 3 levels of healthcare, thus leading to a majority of antibiotics being prescribed in primary care. Relatively high prescription rates for all foci of RTIs were found, which was not in agreement with the national guidelines. Antibiotic stewardship needs improvement at all 3 levels of healthcare. Guidelines to prescribe small spectrum antibiotics for RTIs need to be better implemented in hospital care settings.

Parents' Perspectives and Societal Acceptance of Implementation of Newborn Screening for SCID in the Netherlands.

PURPOSE: While neonatal bloodspot screening (NBS) for severe combined immunodeficiency (SCID) has been introduced more than a decade ago, implementation in NBS programs remains challenging in many countries. Even if high-quality test methods and follow-up care are available, public uptake and parental acceptance are not guaranteed. The aim of this study was to describe the parental perspective on NBS for SCID in the context of an implementation pilot. Psychosocial aspects have never been studied before for NBS for SCID and are important for societal acceptance, a major criterion when introducing new disorders in NBS programs. METHODS: To evaluate the perspective of parents, interviews were conducted with parents of newborns with abnormal SCID screening results (N = 17). In addition, questionnaires about NBS for SCID were sent to 2000 parents of healthy newborns who either participated or declined participation in the SONNET-study that screened 140,593 newborns for SCID. RESULTS: Support for NBS for SCID was expressed by the majority of parents in questionnaires from both a public health perspective and a personal perspective. Parents emphasized the emotional impact of an abnormal screening result in interviews. (Long-term) stress and anxiety can be experienced during and after referral indicating the importance of uniform follow-up protocols and adequate information provision. CONCLUSION: The perspective of parents has led to several recommendations for NBS programs that are considering screening for SCID or other disorders. A close partnership of NBS programs' stakeholders, immunologists, geneticists, and pediatricians-immunologists in different countries is required for moving towards universal SCID screening for all infants.

MKL1 deficiency results in a severe neutrophil motility defect due to impaired actin polymerization.

Megakaryoblastic leukemia 1 (MKL1) promotes the regulation of essential cell processes, including actin cytoskeletal dynamics, by coactivating serum response factor. Recently, the first human with MKL1 deficiency, leading to a novel primary immunodeficiency, was identified. We report a second family with 2 siblings with a homozygous frameshift mutation in MKL1. The index case died as an infant from progressive and severe pneumonia caused by Pseudomonas aeruginosa and poor wound healing. The younger sibling was preemptively transplanted shortly after birth. The immunodeficiency was marked by a pronounced actin polymerization defect and a strongly reduced motility and chemotactic response by MKL1-deficient neutrophils. In addition to the lack of MKL1, subsequent proteomic and transcriptomic analyses of patient neutrophils revealed actin and several actin-related proteins to be downregulated, confirming a role for MKL1 as a transcriptional coregulator. Degranulation was enhanced upon suboptimal neutrophil activation, whereas production of reactive oxygen species was normal. Neutrophil adhesion was intact but without proper spreading. The latter could explain the observed failure in firm adherence and transendothelial migration under flow conditions. No apparent defect in phagocytosis or bacterial killing was found. Also, monocyte-derived macrophages showed intact phagocytosis, and lymphocyte counts and proliferative capacity were normal. Nonhematopoietic primary fibroblasts demonstrated defective differentiation into myofibroblasts but normal migration and F-actin content, most likely as a result of compensatory mechanisms of MKL2, which is not expressed in neutrophils. Our findings extend current insight into the severe immune dysfunction in MKL1 deficiency, with cytoskeletal dysfunction and defective extravasation of neutrophils as the most prominent features.

Successful Systemic and Topical Treatment of Mycobacterium abscessus Otomastoiditis.

Mycobacterium abscessus is an extensively drug-resistant opportunistic pathogen that can cause chronic otomastoiditis. There are no evidence-based treatment regimens for this severe infection. We treated four children with M. abscessus otomastoiditis with a structured regimen of topical imipenem and tigecycline, intravenous imipenem and tigecycline, and oral clofazimine and azithromycin and adjunctive surgery. This structured approach led to cure, with 1 year of follow-up after treatment. Adverse events were frequent, mostly caused by tigecycline.

Exome sequencing in routine diagnostics: a generic test for 254 patients with primary immunodeficiencies.

BACKGROUND: Diagnosis of primary immunodeficiencies (PIDs) is complex and cumbersome yet important for the clinical management of the disease. Exome sequencing may provide a genetic diagnosis in a significant number of patients in a single genetic test. METHODS: In May 2013, we implemented exome sequencing in routine diagnostics for patients suffering from PIDs. This study reports the clinical utility and diagnostic yield for a heterogeneous group of 254 consecutively referred PID patients from 249 families. For the majority of patients, the clinical diagnosis was based on clinical criteria including rare and/or unusual severe bacterial, viral, or fungal infections, sometimes accompanied by autoimmune manifestations. Functional immune defects were interpreted in the context of aberrant immune cell populations, aberrant antibody levels, or combinations of these factors. RESULTS: For 62 patients (24%), exome sequencing identified pathogenic variants in well-established PID genes. An exome-wide analysis diagnosed 10 additional patients (4%), providing diagnoses for 72 patients (28%) from 68 families altogether. The genetic diagnosis directly indicated novel treatment options for 25 patients that received a diagnosis (34%). CONCLUSION: Exome sequencing as a first-tier test for PIDs granted a diagnosis for 28% of patients. Importantly, molecularly defined diagnoses indicated altered therapeutic options in 34% of cases. In addition, exome sequencing harbors advantages over gene panels as a truly generic test for all genetic diseases, including in silico extension of existing gene lists and re-analysis of existing data.

Impact of bacterial colonization on exhaled inflammatory markers in wheezing preschool children.

Wheeze is a common symptom in preschool children. The role of bacteria, regulatory T (T(reg)) cells and their association with airway inflammation in preschool wheeze is largely unknown. We evaluated inflammatory markers in exhaled breath condensate (EBC), bacterial colonization and circulating T(reg) cells in preschool children with and without recurrent wheeze. We recruited 252 children (aged two to four years) with (N = 202) and without (N = 50) recurrent wheeze. EBC was collected using an efficient closed glass condenser. Inflammatory markers in EBC (Interleukin(IL)-2, IL-4, IL-8, IL-10, IL-13) were assessed using multiplex immunoassay. Nasal and throat swabs were analysed for presence of Streptococcus pneumoniae, Haemophilus (para)influenzae and Staphylococcus aureus. Proportions of T(reg) cells (CD4(+)CD25(high)CD127(-)) were quantified by flow cytometry. Recurrent wheezing children had elevated EBC levels of IL-2, IL-4, IL-10 and IL-13 compared to non-wheezers (odds ratio (95% confidence interval): 1.67 (1.23-2.27): 1.58 (1.15-2.18): 1.47 (1.14-1.90): 1.55 (1.16-2.06), p <0.05, respectively). Bacteria were frequently present in children with and without wheeze, with no difference in prevalence (16-52% versus 16-50%, respectively). Moreover, the proportion of T(reg) cells did not differ between both groups. Wheezing children with bacterial colonization did not significantly differ in exhaled levels of inflammatory markers or proportion of T(reg) cells compared to wheezing children without colonization. The analysis of EBC might serve as a helpful non-invasive tool to early assess airway inflammation in wheezing children. The various elevated exhaled inflammatory markers indicate increased airway inflammation in wheezing preschool children. In the presence of wheeze, we found no evidence for bacterial induced airway inflammation.