Human cells homozygous for rare loss-of-expression (LOE) TYK2 alleles have impaired, but not abolished, cellular responses to IFN-α/β (underlying viral diseases in the patients) and to IL-12 and IL-23 (underlying mycobacterial diseases). Cells homozygous for the common P1104A TYK2 allele have selectively impaired responses to IL-23 (underlying isolated mycobacterial disease). We report three new forms of TYK2 deficiency in six patients from five families homozygous for rare TYK2 alleles (R864C, G996R, G634E, or G1010D) or compound heterozygous for P1104A and a rare allele (A928V). All these missense alleles encode detectable proteins. The R864C and G1010D alleles are hypomorphic and loss-of-function (LOF), respectively, across signaling pathways. By contrast, hypomorphic G996R, G634E, and A928V mutations selectively impair responses to IL-23, like P1104A. Impairment of the IL-23–dependent induction of IFN-γ is the only mechanism of mycobacterial disease common to patients with complete TYK2 deficiency with or without TYK2 expression, partial TYK2 deficiency across signaling pathways, or rare or common partial TYK2 deficiency specific for IL-23 signaling.

Antibiotic-associated diarrhea (AAD) is one of the side effects that occur during and after antibiotic use. Some probiotics have strain-specific beneficial effects on AAD development when used in combination with antibiotics. The aim of this study was to evaluate the effect of Limosilactobacillus reuteri DSM 17938 on the prevention of AAD in children. This is a prospective, multicenter, randomized, double-blind, placebo-controlled clinical trial in Türkiye between 2017–2019, among outpatient children with acute otitis media (AOM) or acute rhinosinusitis (ARS). Group 1 (n = 330) received amoxicillin-clavulanate and L. reuteri DSM 17938 (2 × 10⁸ CFU) and Group 2 (n = 324) received amoxicillin-clavulanate and a placebo during the antibiotic treatment or continued for 21 days after antibiotic cessation. The primary end point of this study was the percentage of children with AAD in the first 14, 21, and 56 days of follow-up. Secondary endpoints are the percentage of children with AAD regarding the AOM vs ARS, amoxicillin-clavulanate dose, age groups, and the comparison between 14- and 21-days use of L. reuteri. The percentage of children with AAD was significantly lower in the L. reuteri group compared to the placebo group at 14 days (7.9% vs. 16.7%; RR: 0.47, 95%CI 0.30–0.7; p < 0.001); at 21 days (8.8% vs. 17.9%; RR: 0.49, 95%CI 0.32–0.74;p < 0.001); and at 56 days (9.1% vs. 19.6%; RR: 0.46, 95%CI 0.30–0.69;p < 0.001). The incidence of AAD was also significantly lower in the L. reuteri group at 14, 21 and 56 days among children aged between 6–24 months (p < 0.01, p < 0.01, p < 0.001) or children with AOM (p = 0.0001,p < 0.0001,p < 0.0001). When AAD was observed, the mean duration of diarrhea was longer in the placebo group(p < 0.05). Conclusions: This first study with L. reuteri DSM 17938 in a large pediatric outpatient setting showed significant reduction of AAD during the first 14 days of antibiotic use and the 8-week follow-up period. Trial Registration: NCT02765217 (First Submitted 02.05.2016) (https://clinicaltrials.gov/study/NCT02765217?term=NCT02765217&rank=1). What is known:• Antibiotic associated diarrhea (AAD) is one of the common complications of antibiotic use in children and selected probiotics may have a strain-specific effect to prevent AAD• There are limited studies about the effects of Limosilactobacillus reuteri DSM 17938 on AAD, and no study available in pediatric outpatient setting. What is new:• Limosilactobacillus reuteri DSM 17938 significantly reduced the incidence of AAD in children at 14-, 21-, and 56- days follow-up.• The effect is mainly observed in children aged between 6 and 24 months or children with AOM.

Meningococcal carriage studies and transmission modeling can predict IMD epidemiology and used to define invasive meningococcal disease (IMD) control strategies. In this multicenter study, we aimed to evaluate the prevalence of nasopharyngeal Neisseria meningitidis (Nm) carriage, serogroup distribution, and related risk factors in Turkey. Nasopharyngeal samples were collected from a total of 1267 children and adolescents and were tested with rt-PCR. Nm carriage was detected in 96 participants (7.5%, 95% CI 6.1–9.0), with the peak age at 13 years (12.5%). Regarding age groups, Nm carriage rate was 7% in the 0–5 age group, was 6.9%in the 6–10 age group, was 7.9% in the 11–14 age group, and was 9.3% in the 15–18 age group. There was no statistically significant difference between the groups (p > 0.05). The serogroup distribution was as follows: 25% MenX, 9.4% MenA, 9.4% MenB, 2.1% MenC, 3.1% MenW, 2.1% for MenY, and 48.9% for non-groupable. The Nm carriage rate was higher in children with previous upper respiratory tract infections and with a high number of household members, whereas it was lower in children with antibiotic use in the last month (p < 0.05 for all). In this study, MenX is the predominant carriage strain. The geographical distribution of Nm strains varies, but serogroup distribution in the same country might change in a matter of years. Adequate surveillance and/or a proper carriage study is paramount for accurate/dynamic serogroup distribution and the impact of the proposed vaccination.