Multisystem inflammatory syndrome in children (MIS-C) is a hyperinflammatory condition caused by recent SARS-CoV-2 infection, but the underlying immunological mechanisms driving this distinct syndrome are unknown.We utilized high dimensional flow cytometry, cell-free (cf) DNA, and cytokine and chemokine profiling to identify mechanisms of critical illness distinguishing MIS-C from severe acute COVID-19 (SAC).Compared to SAC, MIS-C patients demonstrated profound innate immune cell death and features of emergency myelopoiesis (EM), an understudied phenomenon observed in severe inflammation. EM signatures were characterized by fewer mature myeloid cells in the periphery and decreased expression of HLA-DR and CD86 on antigen presenting cells. IL-27, a cytokine known to drive hematopoietic stem cells towards EM, was increased in MIS-C, and correlated with immature cell signatures in MIS-C. Upon recovery, EM signatures decreased, and IL-27 plasma levels returned to normal levels. Despite profound lymphopenia, we report a lack of cfDNA released by adaptive immune cells and increased CCR7 expression on T cells indicative of egress out of peripheral blood.Immune cell signatures of EM combined with elevated innate immune cell-derived cfDNA levels distinguish MIS-C from SAC in children and provide mechanistic insight into dysregulated immunity contributing towards MIS-C, offering potential diagnostic and therapeutic targets.

BACKGROUND: Enterococcal meningitis in children is rare, and its clinical presentation, laboratory characteristics and outcomes are not well defined. METHODS: We conducted a retrospective analysis of Enterococcal meningitis cases during 2002-2023 at our tertiary center. RESULTS: We identified 10 cases in children aged 2 weeks to 15 years (median age: 8 months). Seven children were males and 9 had comorbidities, including a ventriculoperitoneal shunt in 5 children. All children with shunt infections presented with nonspecific signs and symptoms. While 8 children presented with fever, only 3 had signs of meningeal irritation and altered consciousness. Cerebrospinal fluid pleocytosis was evident in almost all children with a median of 173 cells/mL. Nine cases were due to Enterococcus faecalis, and 1 case was due to E. faecium. All 5 children with ventriculoperitoneal shunt underwent shunt removal and replacement. All children recovered without documented sequelae. CONCLUSIONS: Enterococcal meningitis is rare, especially in healthy neonates. It typically occurs following neurosurgical interventions and may only present with fever and shunt malfunction, without overt meningeal signs and with mild inflammation. The prognosis is favorable.

Congenital cytomegalovirus (cCMV) is the most common intrauterine infection, leading to neurodevelopmental disabilities. Universal newborn infant screening of cCMV has been increasingly advocated. In the absence of a high-throughput screening test, which can identify all infected newborn infants, the development of an accurate and efficient testing strategy has remained an ongoing challenge. Here we assessed the implementation of pooled saliva polymerase chain reaction (PCR) tests for universal screening of cCMV, in two hospitals of Jerusalem from April 2022 through April 2023. During the 13-month study period, 15,805 infants (93.6% of all live newborn infants) were screened for cCMV using the pooled approach that has since become our routine screening method. The empirical efficiency of the pooling was six (number of tested newborn infants per test), thereby sparing 83% of the saliva tests. Only a minor 3.05 PCR cycle loss of sensitivity was observed for the pooled testing, in accordance with the theoretical prediction for an eight-sample pool. cCMV was identified in 54 newborn infants, with a birth prevalence of 3.4 per 1,000; 55.6% of infants identified with cCMV were asymptomatic at birth and would not have been otherwise targeted for screening. The study demonstrates the wide feasibility and benefits of pooled saliva testing as an efficient, cost-sparing and sensitive approach for universal screening of cCMV.

Fever in infants presenting to pediatric emergency departments (PEDs) often results in significant return visits (RVs). This retrospective study aimed to identify factors associated with RVs in febrile infants aged 0 to 90 days. Data from infants presenting to PED between 2018 and 2021 and returning within 7 days (RV group) were compared to age-matched febrile infants without RVs (control group). Each group had 95 infants with similar demographics and medical history. RVs were primarily due to positive cultures and persistent fever. The control group had higher initial hospitalization rates, longer PED stays, and increased antibiotic treatment. Prevalence of serious bacterial infections (SBIs) did not significantly differ. Higher hospitalization, prolonged PED stays, and initial antibiotic treatment were associated with reduced RV incidence despite similar SBI rates. Return visits in infants <90 days were primarily driven by persistent fever and positive cultures. Addressing these factors through targeted parental education and improved care protocols may reduce RVs.

Helicobacter cinaedi is known to cause invasive infections in immunocompromised adults. Here we report the first case of H. cinaedi bacteremia in a child with nephrotic syndrome. The patient presented with a mild transient febrile illness that resolved spontaneously. We discuss the diagnostic challenges associated with this case and the microbiologic approach, including genomic analysis. Furthermore, we review the current case together with all previous pediatric cases (n = 6). Notably, all cases involved neonates or otherwise immunocompromised individuals and were characterized by severe disease with complicated infections (eg, meningitis, cholangitis and arthritis). H. cinaedi bacteremia in children is associated with a wide spectrum of clinical presentations ranging from mild to life-threatening conditions. This bacterium may be difficult to diagnose and require specialized methods.

While antimicrobials are among the most prescribed drugs, the use of some older antibiotics is not optimized for efficacy in terms of dosage, route of administration, and duration of therapy. Knowledge gaps exist regarding the heterogeneous microenvironments within different infected tissues consisting of varying bacterial loads, immune responses, and drug gradients. Positron-emission tomography-based imaging, where radiolabeled drugs are visualized within the living body, enables accurate, holistic, and real-time determination of pharmacokinetics to provide valuable, actionable data to optimize antibiotic use. Here we briefly review the concepts, history, and recent progress in the field.

BACKGROUND CONTEXT: Bacterial infection of spinal instrumentation is a significant challenge in spinal fusion surgery. Although the intraoperative local application of powdered vancomycin is common practice for mitigating infection, the antimicrobial effects of this route of administration are short-lived. Therefore, novel antibiotic-loaded bone grafts as well as a reliable animal model to permit the testing of such therapies are needed to improve the efficacy of infection reduction practices in spinal fusion surgery. PURPOSE: This study aims to establish a clinically relevant rat model of spinal implant-associated infection to permit the evaluation of antimicrobial bone graft materials used in spinal fusion. STUDY DESIGN: Rodent study of chronic spinal implant-associated infection. METHODS: Instrumentation anchored in and spanning the vertebral bodies of L4 and L5 was inoculated with bioluminescent methicillin-resistant Staphylococcus aureus bacteria (MRSA). Infection was monitored using an in vivo imaging system (IVIS) for 8 weeks. Spines were harvested and evaluated histologically, and colony-forming units (CFUs) were quantified in harvested implants and spinal tissue. RESULTS: Postsurgical analysis of bacterial infection in vivo demonstrated stratification between MRSA and phosphate-buffered saline (PBS) control groups during the first 4 weeks of the 8-week infection period, indicating the successful establishment of acute infection. Over the 8-week chronic infection period, groups inoculated with 1 × 105 MRSA CFU and 1 × 106 MRSA CFU demonstrated significantly higher bioluminescence than groups inoculated with PBS control (p = 0.009 and p = 0.041 respectively). Histological examination at 8 weeks postimplantation revealed the presence of abscesses localized to implant placement in all MRSA inoculation groups, with the most pervasive abscess formation in samples inoculated with 1 × 105 MRSA CFU and 1 × 106 MRSA CFU. Quantification of CFU plated from harvested spinal tissue at 8 weeks post-implantation revealed the 1 × 105 MRSA CFU inoculation group as the only group with a significantly greater average CFU count compared to PBS control (p = 0.017). Further, CFU quantification from harvested spinal tissue was greater than CFU quantification from harvested implants across all inoculation groups. CONCLUSION: Our model demonstrated that the inoculation dosage of 1 × 105 MRSA CFU exhibited the most robust chronic infection within instrumented vertebral bodies. This dosage had the greatest difference in bioluminescence signal from control (p < 0.01), the lowest mortality (0% compared to 50% for samples inoculated with 1 × 106 MRSA CFU), and a significantly higher amount of CFUs from harvested spine samples than CFUs from control harvested spine samples. Further, histological analysis confirmed the reliability of this novel rodent model of implanted-associated infection to establish infection and biofilm formation of MRSA for all inoculation groups. CLINICAL SIGNIFICANCE: This model is intended to simulate the infection of instrumentation used in spinal fusion surgeries concerning implant locality and material. This model may evaluate potential antimicrobial and osteogenic biomaterials and investigate the relationship between implant-associated infection and failed fusion.

OBJECTIVES: There are scant data on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in infants younger than 90 days. This study was designed to characterize COVID-19 presentation and clinical course in this age group and evaluate the risk of serious bacterial infection. METHODS: Data on all SARS-CoV-2-polymerase chain reaction-positive infants presenting to the pediatric emergency department (PED) were retrospectively collected, followed by a case-control study comparing those infants presenting with fever (COVID group) to febrile infants presenting to the PED and found to be SARS-CoV-2 negative (control group). RESULTS: Of the 96 PCR-positive SARS-CoV-2 infants who met the inclusion criteria, the most common presenting symptom was fever (74/96, 77.1%) followed by upper respiratory tract infection symptoms (42/96, 43.8%). Four (4.2%) presented with symptoms consistent with brief resolved unexplained event (4.2%).Among the febrile infants, the presenting symptoms and vital signs were similar in the COVID and control groups, with the exception of irritability, which was more common in the control group (8% and 26%; P < 0.01). The SARS-CoV-2-positive infants had decreased inflammatory markers including: C-reactive protein (0.6 ± 1 mg/dL vs 2.1 ± 2.7 mg/dL; P < 0.0001), white blood cell count (9.3 ± 3.4 × 109/L vs 11.8 ± 5.1 × 109/L; P < 0.001), and absolute neutrophils count (3.4 ± 2.4 × 109/L vs 5.1 ± 3.7 × 109/L; P < 0.001). The rate of invasive bacterial infection was similar between groups (1.4% and 0%; P = 0.31). No mortality was recorded. Although not significantly different, urinary tract infections were less common in the COVID group (7% and 16%; P = 0.07). CONCLUSIONS: The SARS-CoV-2 infection in infants aged 0 to 90 days who present to the PED seems to be mostly mild and self-limiting, with no increased risk of serious bacterial infection.

Background and Objectives Convalescent COVID-19 plasma (CCP) was developed and used worldwide as a treatment option by supplying passive immunity. Adult studies suggest administering high-titer CCP early in the disease course of patients who are expected to be antibody-negative; however, pediatric experience is limited. We created a multi-institutional registry to characterize pediatric patients (<18 years) who received CCP and assess the safety of this intervention. Methods A REDCap survey was distributed. The registry collected de-identified data including demographic information (age, gender, and underlying conditions), COVID-19 disease features and concurrent treatments, CCP transfusion and safety events, and therapy response. Results Ninety-five children received CCP: 90 inpatients and 5 outpatients, with a median age of 10.2 years (range 0-17.9), predominantly Latino/Hispanic and White. The most frequent underlying medical conditions were chronic respiratory disease, immunosuppression, obesity, and genetic syndromes. CCP was primarily given as a treatment (95%) rather than prophylaxis (5%). Median total plasma dose administered and transfusion rates were 5.0 mL/kg and 2.6 mL/kg/hr, respectively. The transfusions were well tolerated, with 3 in 115 transfusions reporting mild reactions. No serious adverse events were reported. Severity scores decreased significantly 7 days after CCP transfusion or at discharge. Eight-five patients (94.4%) survived to hospital discharge. All five outpatients survived to 60 days. Conclusions CCP was found to be safe and well tolerated in children. CCP was frequently given concurrently with other COVID-19-directed treatments with improvement in clinical severity scores ≥ 7 days after CCP, but efficacy could not be evaluated in this study.

Introduction: Staphylococcus aureus bacteremia (SAB) in children is associated with significant mortality and morbidity, including recurrent bacteremia. Infectious disease consultation (IDC) improves SAB outcomes in adult patients. However, increasing IDC and impact for pediatric patients with SAB is not well described. Methods: This quality improvement project aimed to increase IDC for SAB events at a quaternary pediatric medical center. First, we evaluated the local practices regarding pediatric SAB and engaged stakeholders (July 2018–August 2020). We added an advisory comment supporting IDC for SAB to all blood culture results in September 2020. Using statistical process control charts, we monitored the number of SAB events with IDC before a SAB event without IDC. Finally, we evaluated SAB recurrences before and after initiating the advisory comment. Results: In the baseline period, 30 of 49 (61%) SAB events received an IDC with a mean of 1.4 SAB events with IDC before a SAB event without IDC. Postintervention, 22 of 23 (96%) SAB events received IDC with a mean of 14 events with IDC before 1 event without IDC. The SAB recurrence rate was 8%, with 6 events in 4 children; none of the index cases resulting in recurrence received an IDC (P = 0.0002), and all occurred before any intervention. Conclusions: An electronic advisory comment supporting IDC for SAB significantly increased the rate of pediatric IDC with no further SAB recurrence episodes following intervention. This low-resource intervention may be considered in other pediatric centers to optimize SAB management.

Staphylococcus aureus is an important cause of various infections in humans, including bacteremia, skin and soft tissue infections, and infections associated with implanted medical devices. The emergence of hospital- and community-acquired methicillin-resistant Staphylococcus aureus (MRSA) underscores the urgent and unmet need to develop novel, safe, and effective antibiotics against these multidrug-resistant clinical isolates. Oxazolidinone antibiotics such as linezolid have excellent oral bioavailability and provide coverage against MRSA infections. However, their widespread and long-term use is often limited by adverse effects, especially myelosuppression. TBI-223 is a novel oxazolidinone with potentially reduced myelosuppression, compared to linezolid, but its efficacy against MRSA infections is unknown. Therefore, the preclinical efficacy of TBI-223 (80 and 160 mg/kg twice daily) was compared with that of linezolid (40 and 80 mg/kg twice daily) and sham treatment in mouse models of MRSA bacteremia, skin wound infection, and orthopedic-implant-associated infection. The dosage was selected based on mouse pharmacokinetic analysis of both linezolid and TBI-223, as well as measurement of the MICs. In all three models, TBI-223 and linezolid had comparable dose-dependent efficacies in reducing bacterial burden and disease severity, compared with sham-treated control mice. Taken together, these findings indicate that TBI-223 represents a novel oxazolidinone antibiotic that may provide an additional option against MRSA infections. Future studies in larger animal models and clinical trials are warranted to translate these findings to humans. IMPORTANCE Staphylococcus aureus is the predominant cause of bloodstream, skin, and bone infections in humans. Resistance to commonly used antibiotics is a growing concern, making it more difficult to treat staphylococcal infections. Use of the oxazolidinone antibiotic linezolid against resistant strains is hindered by high rates of adverse reactions during prolonged therapy. Here, a new oxazolidinone named TBI-223 was tested against S. aureus in three mouse models of infection, i.e., bloodstream infection, skin infection, and bone infection. We found that TBI-223 was as effective as linezolid in these three models. Previous data suggest that TBI-223 has a better safety profile than linezolid. Taken together, these findings indicate that this new agent may provide an additional option against MRSA infections. Future studies in larger animal models and clinical trials are warranted to translate these findings to humans.

{Background Multisystem Inflammatory Syndrome in Children (MIS-C) is a severe clinical phenotype of SARS-CoV-2 infection that remains poorly understood. Methods Hospitalized children <18 years of age with suspected COVID-19 (N=53) were recruited into a prospective cohort study; 32 had confirmed COVID-19, with 16 meeting the U.S. Centers for Disease Control criteria for MIS-C. Differences in nasopharyngeal viral RNA levels, SARS-CoV-2 seropositivity, and cytokine/chemokine profiles were examined, including after adjustments for age and sex. Results The median ages for those with and without MIS-C were 8.7 years (IQR 5.5-13.9) and 2.2 years (IQR 1.1-10.5), respectively, (p=0.18) and nasopharyngeal levels of SARS-CoV-2 RNA did not differ significantly between the two groups (median 63,848.25 copies/mL versus 307.1 copies/mL

Skip to Next Section Post-surgical implant-associated spinal infection is a devastating complication commonly caused by Staphylococcus aureus. Biofilm formation is thought to reduce penetration of antibiotics and immune cells, contributing to chronic and difficult-to-treat infections. A rabbit model of a posterior-approach spinal surgery was created, in which bilateral titanium pedicle screws were interconnected by a plate at the level of lumbar vertebra L6 and inoculated with a methicillin-resistant S. aureus (MRSA) bioluminescent strain. In vivo whole-animal bioluminescence imaging (BLI) and ex vivo bacterial cultures demonstrated a peak in bacterial burden by day 14, when wound dehiscence occurred. Structures suggestive of biofilm, visualized by scanning electron microscopy, were evident up to 56 days following infection. Infection-induced inflammation and bone remodeling were also monitored using 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and computed tomography (CT). PET imaging signals were noted in the soft tissue and bone surrounding the implanted materials. CT imaging demonstrated marked bone remodeling and a decrease in dense bone at the infection sites. This rabbit model of implant-associated spinal infection provides a valuable preclinical in vivo approach to investigate the pathogenesis of implant-associated spinal infections and to evaluate novel therapeutics.

Background: Mycoplasma pneumoniae (MP) is a major cause of community-acquired upper and lower respiratory infections in school-age children; however, there is increasing recognition that younger children are also affected. Clinical manifestations vary from asymptomatic, to severe complicated pneumonia sometimes with extrapulmonary manifestations. Methods: We reviewed the medical records of all MP positive pediatric patients admitted to the Hadassah-Hebrew University Medical Center. MP positive case was defined if MP polymerase chain reaction was positive from an oropharyngeal swab sent from 2007 to 2017. Results: During the study period, we identified 353 MP positive pediatric cases, of which 51.3% (181 out of 353) were younger than 6 years old. Full clinical data were available for 332 of 353 (94%). The median age was 5.7 years (range, 3 weeks to 18 years). Disease presentation differed between younger and older children. Children older than 6 years were more likely to have chest x-ray–confirmed pneumonia (66% vs. 52%; P = 0.009), while younger children were more likely to have other respiratory manifestations (37% vs. 25%; P = 0.017). The duration of hospitalization and pediatric intensive care unit admission rate, however, did not differ between age groups. The rate of extrapulmonary manifestations were also similar. Conclusions: MP-associated infection is a significant cause of hospitalization in the pediatric population including younger children (<6 years old). However, the clinical presentation in younger age is less typical than is thought. These findings should prompt clinicians to consider MP infections also in children younger than 6 admitted with fever even without pneumonia.

Rationale Necrotizing pneumonia is characterized by destruction and liquefaction of the lung tissue and loss of the normal pulmonary parenchymal architecture. During the course of resolution areas of hyperlucency are formed, sometimes with the development of giant lung cysts that can be a field with fluid resembling lung abscess. There is no consensus on the management of these abnormalities. Objective To assess the prevalence of giant lung cysts as a complication of necrotizing pneumonia and to report our experience with conservative treatment that achieved complete resolution. Methods Medical chart reviews of all children aged 0 to 18 years hospitalized with necrotizing pneumonia in a single tertiary center from 2015 to 2017, demographic data, and clinical course during and after hospitalization as well as serial chest imaging were collected. Results During the study period, 761 children were diagnosed with community-acquired pneumonia, 16 of 761 (2.3%) had necrotizing pneumonia and 6 of 16 (37.5%) with necrotizing pneumonia complicated by a giant lung cyst or lung abscess. All were closely observed and showed complete clinical and radiographic resolution with antibiotic treatment. Conclusions Treatment of giant lung cyst formation following necrotizing pneumonia by a conservative approach with prolonged antibiotics results in complete recovery with no need for invasive procedures.

Streptococcus pneumoniae (Spn) rapidly kills Staphylococcus aureus (Sau) by producing membrane-permeable hydrogen peroxide (H2O2). The mechanism by which Spn-produced H2O2 mediates Sau killing was investigated. An in vitro model that mimicked Spn-Sau contact during colonization of the nasopharynx demonstrated that Sau killing required outcompeting densities of Spn. Compared to the wildtype strain, isogenic SpnΔlctO, and SpnΔspxB, both deficient in production of H2O2, required an increased density to kill Sau. While residual H2O2 activity produced by single mutants was sufficient to eradicate Sau, a double SpnΔspxB/ΔlctO mutant was unable to kill. A collection of 20 diverse MRSA and MSSA strains showed linear sensitivity (R2=0.95) for Spn killing, but the same strains had different susceptibilities when challenged against pure H2O2 (5 mM). There was no association between Sau clonal complex and sensitivity to either Spn or H2O2. To kill Sau, Spn produced ∼180 μM of H2O2 within 4 h of incubation, while killing-defective SpnΔspxB and SpnΔspxB/lctO mutants produced undetectable levels. Remarkably, a sublethal dose (1 mM) of pure H2O2 when incubated with SpnΔspxB eradicated diverse Sau strains suggesting that Spn bacteria may facilitate conversion of H2O2 to a hydroxyl radical (•OH). Accordingly, Sau killing was completely blocked by incubating with scavengers of •OH radicals, Me2SO, thiourea, or sodium salicylate. The •OH was detected in the supernatant of Spn by spin trapping and electron paramagnetic resonance. Therefore, Spn produces H2O2 which is rapidly converted to a more potent oxidant, the hydroxyl radicals, to rapidly intoxicate Sau strains. Importance Streptococcus pneumoniae (Spn) strains produces hydrogen peroxide (H2O2) to kill bacteria in the upper airways, including pathogenic Staphylococcus aureus (Sau) strains. Targets of Spn-produced H2O2 have not been discovered in part because of a lack of knowledge about the underlying molecular mechanism. We demonstrated that an increased density of Spn kills Sau by means of H2O2 produced by two enzymes, SpxB and LctO. We discovered that SpxB/LctO-produced H2O2 is converted into a hydroxyl (•OH) radical that rapidly intoxicates and kills Sau. We successfully inhibited the toxicity of •OH with three different scavengers and detected •OH in the supernatant. The target(s) of the hydroxyl radicals represents a new alternative for the development of antimicrobials against Sau infections.