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Introduction: Limited data are available regarding SARS-CoV-2 serological response dynamics in pediatric patients with COVID-19, contributing to gaps in our understanding of the immune response in this population. This study aimed to investigate SARS-CoV-2 IgG seropositivity in patients diagnosed with COVID-19 during hospitalization and 2-4 weeks after discharge. Methods: A cohort of patients, consisting of 31 individuals with confirmed acute COVID-19 infection and 27 diagnosed with Multisystem Inflammatory Syndrome in Children (MIS-C), was enrolled in the study. Follow-up clinic appointments were scheduled for 2-4 weeks post-discharge. During admission and follow-up, blood samples were collected from each patient for laboratory analysis. Anti-nucleoprotein SARS-CoV-2 IgG levels were determined using the Enzyme-Linked Immunosorbent Assay (ELISA) method. Results: In this study, a cohort of 58 patients was examined. At admission, 52% (n = 14) of MIS-C patients and 10% (n = 3) of acute COVID-19 patients had positive SARS-CoV-2 IgG test. Only 48 cases were referred to the hospital, and follow-up data was available for 20 cases with MIS-C and 28 cases with acute COVID-19. All patients (n = 15) who initially tested positive for SARS-CoV-2 IgG at admission remained positive serology during follow-up (100%). Among the 33 patients who initially tested negative, 12 (37.5%) showed a positive serology result during follow-up, while 21 (62.5%) remained negative. Within this subgroup, 11 cases (44%) were diagnosed with acute COVID-19, and one patient (12.5%) presented with MIS-C. Fourteen cases with acute COVID-19 infection (56%) and seven cases with MIS-C (87.5%) consistently showed negative serology results throughout the study. During follow-up, the median lymphocyte count demonstrated a significant difference, with 0.96 x 109 cells per L (IQR: 0.75-3.0 x 109 cells per L) in the SARS-CoV-2 IgG-negative group and 2.9 x 109 cells per L (IQR = 1.33-7.22 x 109 cells per L) in the SARS-CoV-2 IgG-positive group (p-value = 0.03). Patients who demonstrated seropositivity during the follow-up were associated with a notably severe disease (p-value = 0.028). Conclusion: Our study highlights the dynamic nature of SARS-CoV-2 IgG antibody responses in pediatric patients with COVID-19 infection. We observed a notable increase in seropositivity rates during follow-up. Furthermore, patients who were seropositive at follow-up demonstrated a severe disease course and lower lymphocyte counts compared to those with persistently negative serology. Our findings underscore the importance of longitudinal serological monitoring in understanding disease progression and immune response dynamics in pediatric COVID-19 cases. [ABSTRACT FROM AUTHOR]

Background: The increasing global concern regarding antibiotic resistance necessitates in-depth studies to comprehend the phenotypic and genotypic characteristics of resistant bacterial strains. This study aimed to investigate the prevalence, antibiotic resistance profiles, and molecular characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates in an Iranian referral pediatrics hospital. Methods: In this study, we examined CRKP isolates collected from hospitalized pediatric patients across various wards. The isolates underwent antimicrobial susceptibility testing, the polymerase chain reaction (PCR) analysis for carbapenemase genes (blaNDM, blaVIM and blaIMP), and genetic relatedness assessment using pulsed-field gel electrophoresis (PFGE). Results: Among 166 K. pneumoniae isolates, 54 (32.5%) exhibited resistance to carbapenems. Notably, all these resistant isolates were resistant to imipenem, with 35 (65%) displaying resistance to both imipenem and meropenem. Of the 54 CRKP isolates, 24 (44%) were metallo-β-lactamases (MBL)-producing. The prevalence of the blaNDM gene among CKCP and MBL-producing isolates was 20% (n = 11) and 44% (n = 24), respectively. The blaVIM and blaIMP genes were not detected in any of the isolates. Twenty-six CRKP isolates (48%) were recovered from ICUs. PFGE analysis of CRKP isolates revealed 20 clusters, with cluster S being the most prevalent, comprising 24% of the total (n = 13). Conclusion: Our study reveals a concerning prevalence of carbapenem resistance in K. pneumoniae isolates. Specifically, the detection of the blaNDM gene in 20% of CRKP isolates, with a significant proportion (82%) observed in isolated CRKP from the ICUs and emergency departments, underscores the potential clonal expansion of these resistant strains within these critical hospital wards. [ABSTRACT FROM AUTHOR]

Diverse clinical and laboratory features of multisystem inflammatory syndrome (MIS‐C) have been reported in the literature. Despite the worldwide distribution, systemic studies regarding the laboratory results do not exist. Therefore, we aimed to perform this systematic review and meta‐analysis to evaluate the serological, immunological, and cardiac parameters of the MIS‐C associated with SARS‐CoV‐2 infection. We searched the PubMed, Scopus, and Web of Science databases using specific keywords for any papers published in English since the disease onset and the first report until July 19, 2020. The inclusion criteria were children <21 years diagnosed with MIS‐C without any limitation on defining criteria. Forty‐eight studies were included in the final analysis, with a total population size of 3543 children with MIS‐C. The median age of the included patients was 8.3 (6.7–9) years. The pooled prevalence of male patients was 59% (95% CI: 56%–61%) and 62% (95% CI: 55%–69%) were admitted in ICU. The pooled prevalence of positive SARS‐CoV‐2 RT‐PCR, SARS‐CoV‐2 IgM, and SARS‐CoV‐2 IgG antibody tests was 33% (95% CI: 27%–40%), 39% (95% CI: 22%–58%) and 81% (95% CI: 76%–86%), respectively. The positivity rate of the inflammatory markers was as follows: CRP (96%, 95% CI: 90%–100%), d‐dimer (87%, 95% CI: 81%–93%), ESR (81%, 95% CI: 74%–87%), procalcitonin (88%, 95% CI: 76%–97%), ferritin (79%, 95% CI: 69%–87%), and fibrinogen (77%, 95% CI: 70%–84%). The pooled prevalence of elevated brain natriuretic peptide (BNP) level, pro‐BNP, and troponin were found in 60% (95% CI: 44%–75%), 87% (95% CI: 75%–96%), and 55% (95% CI: 45%–64%), respectively. The majority of patients had positive SARS‐CoV‐2 IgG test. Nearly one‐third of the cases showed negative RT‐PCR results. Cardiac and inflammatory markers were elevated in the majority of cases. These findings suggest that hyperinflammation and cardiac dysfunction are common complications of MIS‐C. [ABSTRACT FROM AUTHOR]