Kim Stol

Radboudumc, Amalia Children's Hospital, Nijmegen, The Netherlands

We analysed SARS-CoV-2 PCR Cq values from 3,183 healthcare workers who tested positive between January and August 2022. Median Cq values were lower in symptomatic than in asymptomatic HCW. The difference in Cq values between HCW with mild vs moderate/severe symptoms was statistically significant but negligibly small. To prevent nosocomial infection...

Following an increase in notifiable invasive group A streptococcal (iGAS) infections in the Netherlands, we conducted a survey among 7 hospitals. Pediatric iGAS case numbers were 2-fold higher between July 2021 and June 2022 versus pre-COVID-19. A sharp increase occurred early 2022, most pronounced in <5 years old and for diagnoses empyema and necr...

Based on a survey sent to seven Dutch hospitals, we observed an substantial increase in invasive group A streptococcal infections in children in the Netherlands, comparing the pre-COVID-19 pandemic cohort of 2018-2019 to 2021-2022. The most affected age group were children between 0-5 years. Main diagnosis was pneumonia with empyema. Necrotizing fa...

Dolutegravir 50 mg is registered for use in children weighing 20-40 kg. This approval is based on data from an African paediatric cohort, and no pharmacokinetic data was available from children outside of Africa. This study provides further evidence of the effective use of dolutegravir 50 mg in children weighing 20-40 kg by showing adequate doluteg...

Although fatigue is a common symptom in adult patients with primary immunodeficiencies (PID), data in pediatric patients are limited. The goal of this study is to estimate the prevalence and impact of fatigue in children with PID as reported by patients, parents, and health-care providers. A retrospective single-center observational study was perfo...

Advances in antiretroviral treatment improved the life expectancy of perinatally HIV-infected children. However, growing up with HIV provides challenges in daily functioning. This cross-sectional cohort study investigated the neuropsychological and psychosocial functioning of a group of perinatally HIV-infected children in the Netherlands and compa...

Ureaplasma species are increasingly recognized as relevant pathogens in prenatal, perinatal and postnatal morbidity. They are commonly found as commensals on the mucous membranes of the lower urogenital tract of pregnant women, but when ascending, they can cause bacterial vaginosis, chorioamnionitis, premature birth and postnatal morbidities such a...

Background: Inborn errors of immunity (IEI) are rare diseases, which makes diagnosis a challenge. A better description of the initial presenting manifestations should improve awareness and avoid diagnostic delay. Whilst increased infection susceptibility is a well-known initial IEI manifestation, less is known about the frequency of other presenti...

Although fatigue is a common symptom in adult patients with Primary Immunodeficiencies (PID), data in pediatric patients are limited. The goal of this study is to estimate the prevalence and impact of fatigue in children with PID as reported by patients, parents and health-care providers. A retrospective single center observational study was perfor...

Biomarkers have become an integral part of the clinical decision-making process of clinicians dealing with febrile children. C-reactive protein, procalcitonin and white blood cell count are probably the most studied ones. Crucial to using biomarkers is the understanding of how a test result will alter post-test probabilities and then impact on clin...

A 4-month-old female infant presented with a vesicular lesion on her left hand present since 1 day. A few days prior to presentation, she had a similar lesion on the lower lip. Two days after presentation, she returned with new lesions on her thorax and upper eyelid. PCR of the vesicle was positive for herpes simplex virus type 1. The transmission...

We have previously found that non-typeable Haemophilus influenzae (NTHi) collected from the middle ear of children with otitis media (OM) exhibit increased levels of complement resistance compared to NTHi collected from the nasopharynx. However, it is unknown whether bacteria develop complement resistance in the middle ear, or whether resistance is...

Objectives: Otitis media (OM) is one of the most frequent diseases of childhood, with a minority of children suffering from recurrent acute otitis media (rAOM) or chronic otitis media with effusion (COME), both of which are associated with significant morbidity. We investigated whether the microbiological profiling could be used to differentiate be...

Objectives: Otitis media (OM) is one of the most frequent diseases of childhood, with a minority of children suffering from recurrent acute otitis media (rAOM) or chronic otitis media with effusion (COME), both of which are associated with significant morbidity. We investigated whether the microbiological profiling could be used to differentiate b...

Unlabelled: Nontypeable Haemophilus influenzae (NTHi) is a Gram-negative, human-restricted pathogen. Although this bacterium typically colonizes the nasopharynx in the absence of clinical symptoms, it is also one of the major pathogens causing otitis media (OM) in children. Complement represents an important aspect of the host defense against NTHi...

(A) Growth of 1521062 wild type and 1521062 mutant in sBHI medium. (B) Serum resistance of 1521062 wild type and 1521062 mutant. Statistical analyses with a two-way analysis of variance and the Bonferroni post hoc test. (C and D) Serum resistance of a 1:1 ratio of 1521062 wild type and 1521062 mutant was determined with 40% normal human serum (C) o...

List of genes identified in the serum resistance GAF screen.

LOS analysis of the R2866, 1521062, Rd, 3655, and 86-028NP wild-type and mutant strains by Tris-Tricine SDS-PAGE and silver staining. Download Figure S1, TIFF file, 1.7 MB.

List of strains, plasmids, and primers used in this study.

: Viral upper respiratory tract infections have been described as an important factor in the development of otitis media (OM), although it is unclear whether they facilitate bacterial OM or can directly cause OM. To clarify the role of viral infections in OM, we compared the relative contribution of viruses and bacteria with the induction of inflam...

A prospective clinical cohort study was established to investigate the humoral immune response in middle ear fluids (MEF) and serum against bacterial surface proteins in children suffering from recurrent acute otitis media (rAOM) and chronic otitis media with effusion (COME), using Luminex xMAP technology. The association between the humoral immune...

Streptococcus pneumoniae is an important human bacterial pathogen, causing such infections as pneumonia, meningitis, septicemia, and otitis media. Current capsular polysaccharide-based conjugate vaccines protect against a fraction of the over 90 serotypes known, whereas vaccines based on conserved pneumococcal proteins are considered promising broa...

Table S2: Conservation of known and putative virulence factors. Each genome was queried for the presence of known or putative M. catarrhalis virulence factors by annotation record and/or sequence homology. * Denotes presence of ORF(s) homologous to mchA1/2 over 1 Kb or greater of the total length of the ORF.

Table S1: Reconstruction of M. catarrhalis Central Metabolic Pathways. Highlighted cells denote differences between strains; n.p. = ORFs not present in one or more strains. * denotes inclusion of RH4 gene annotation data obtained using the Institute for Genome Science annotation engine [13], while ^ denotes RH4 gene annotation data obtained using P...

M. catarrhalis is a gram-negative, gamma-proteobacterium and an opportunistic human pathogen associated with otitis media (OM) and exacerbations of chronic obstructive pulmonary disease (COPD). With direct and indirect costs for treating these conditions annually exceeding $33 billion in the United States alone, and nearly ubiquitous resistance to...

Deletion of psrP-secY2A2 alters bacteria interactions in mature biofilms. A) Micrographs of mature TIGR4 and T4 ΩpsrP-secY2A2 biofilms. Bacteria were grown in THB at 37° C in 5% CO2 on glass slides within a flow cell under once-through flow conditions for 3 days. For visualization, bacteria were stained with Live/Dead BacLight stain. Biofilms were...

Illustration of the psrP loci in TIGR4 & T4R, T4 ΩpsrP & T4R ΩpsrP, and assorted pNE1 plasmids encoding truncated versions of psrP. (0.08 MB PDF)

Far Western analyses using a GST tagged protein (TC0109) from Chlamydia trachomatis as a probe for non-specific interactions due to the Gst-tag. Membranes were spotted with either A) lysates from S. pneumoniae expressing truncated versions of PsrP; B) truncated versions of His tagged rBR expressed and purified from E. coli; or C) whole cell lysates...

Immunofluorescent imaging of S. pneumoniae in the alveolar space. Frozen lung sections from TIGR4 and T4 ΔpsrP infected mice were processed for imaging using anti-serotype 4 capsular antiserum (Statens Serum Institute; Denmark). Images were taken at 600× and are representative. Note the detection of a large bacterial aggregate (green) for TIGR4 inf...

Purification of a glycosylated PsrP construct. A) Illustration of the psrPSRR2(33)-HIS locus in the expression vector pNE1. The plasmid was used to express and purify glycosylated PsrP from S. pneumoniae, strain TIGR4 cell lysates. Note the presence of fcsRK, a pneumococcal fucose-inducible promoter, also that the cell wall anchor domain has been r...

Antiserum against TIGR4 BR inhibits biofilm formation of unrelated clinical isolates that carry PsrP. Low passage clinical isolates of S. pneumoniae carrying PsrP (TNE-6050, TNE 6012) or without (IPD-5), were grown in silicone coated lines under once-through conditions at 37°C in 5% CO2 for 3 days. THB was supplemented with either naïve rabbit seru...

The Pneumococcal serine-rich repeat protein (PsrP) is a pathogenicity island encoded adhesin that has been positively correlated with the ability of Streptococcus pneumoniae to cause invasive disease. Previous studies have shown that PsrP mediates bacterial attachment to Keratin 10 (K10) on the surface of lung cells through amino acids 273-341 loca...

To evaluate availability and reliability of pediatric drug dosing guidelines in selected formularies for intensive care patients. Most drugs used in the pediatric intensive care unit are prescribed off-label, often on the guidance of limited information from commonly used drug formularies. Availability of dosing information on prescribed drugs in a...

Otitis media (OM) is one of the most frequent diseases in childhood, and Streptococcus pneumoniae is among the main causative bacterial agents. Since current experimental models used to study the bacterial pathogenesis of OM have several limitations, such as the invasiveness of the experimental procedures, we developed a non-invasive murine OM mode...