QuantiFERON-TB reversion in children and adolescents with tuberculosis.

We analyzed 136 children with tuberculosis disease or infection and a positive QuantiFERON-TB (QFT) assay, followed-up for a median of 21 months (0.4-11years). QFT reversed in 16.9% of cases, with significant decreases in TB1 (-1.72 vs. -0.03 IU/ml, p=0.001) and TB2 (-1.65 vs. -0.43 IU/ml, p=0.005) levels compared to non-reverters. We found a higher QFT reversion rate among children under 5 years (25.0% vs 11.9%, p=0.042), and those with TST induration <15mm (29% vs 13.3%, p=0.055). Our data reveal that, although QFT test remained positive in the majority of children, reversion occurred in 16% of cases in a progressive and stable pattern. Younger age and reduced TST induration were associated with QFT reversion.

Clinical, microbiological, and molecular characterization of pediatric invasive infections by Streptococcus pyogenes in Spain in a context of global outbreak.

In December 2022, an alert was published in the UK and other European countries reporting an unusual increase in the incidence of Streptococcus pyogenes infections. Our aim was to describe the clinical, microbiological, and molecular characteristics of group A Streptococcus invasive infections (iGAS) in children prospectively recruited in Spain (September 2022-March 2023), and compare invasive strains with strains causing mild infections. One hundred thirty isolates of S. pyogenes causing infection (102 iGAS and 28 mild infections) were included in the microbiological study: emm typing, antimicrobial susceptibility testing, and sequencing for core genome multilocus sequence typing (cgMLST), resistome, and virulome analysis. Clinical data were available from 93 cases and 21 controls. Pneumonia was the most frequent clinical syndrome (41/93; 44.1%), followed by deep tissue abscesses (23/93; 24.7%), and osteoarticular infections (11/93; 11.8%). Forty-six of 93 cases (49.5%) required admission to the pediatric intensive care unit. iGAS isolates mainly belonged to emm1 and emm12; emm12 predominated in 2022 but was surpassed by emm1 in 2023. Spread of M1UK sublineage (28/64 M1 isolates) was communicated for the first time in Spain, but it did not replace the still predominant sublineage M1global (36/64). Furthermore, a difference in emm types compared with the mild cases was observed with predominance of emm1, but also important representativeness of emm12 and emm89 isolates. Pneumonia, the most frequent and severe iGAS diagnosed, was associated with the speA gene, while the ssa superantigen was associated with milder cases. iGAS isolates were mainly susceptible to antimicrobials. cgMLST showed five major clusters: ST28-ST1357/emm1, ST36-ST425/emm12, ST242/emm12.37, ST39/emm4, and ST101-ST1295/emm89 isolates. IMPORTANCE: Group A Streptococcus (GAS) is a common bacterial pathogen in the pediatric population. In the last months of 2022, an unusual increase in GAS infections was detected in various countries. Certain strains were overrepresented, although the cause of this raise is not clear. In Spain, a significant increase in mild and severe cases was also observed; this study evaluates the clinical characteristics and the strains involved in both scenarios. Our study showed that the increase in incidence did not correlate with an increase in resistance or with an emm types shift. However, there seemed to be a rise in severity, partly related to a greater rate of pneumonia cases. These findings suggest a general increase in iGAS that highlights the need for surveillance. The introduction of whole genome sequencing in the diagnosis and surveillance of iGAS may improve the understanding of antibiotic resistance, virulence, and clones, facilitating its control and personalized treatment.

Executive summary: Guidelines for the diagnosis and treatment of septic arthritis in adults and children, developed by the GEIO (SEIMC), SEIP and SECOT.

Infection of a native joint, commonly referred to as septic arthritis, is a medical emergency because of the risk of joint destruction and subsequent sequelae. Its diagnosis requires a high level of suspicion. These guidelines for the diagnosis and treatment of septic arthritis in children and adults are intended for use by any physician caring for patients with suspected or confirmed septic arthritis. They have been developed by a multidisciplinary panel with representatives from the Bone and Joint Infections Study Group (GEIO) belonging to the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), the Spanish Society of Paediatric Infections (SEIP) and the Spanish Society of Orthopaedic Surgery and Traumatology (SECOT), and two rheumatologists. The recommendations are based on evidence derived from a systematic literature review and, failing that, on the opinion of the experts who prepared these guidelines. A detailed description of the background, methods, summary of evidence, the rationale supporting each recommendation, and gaps in knowledge can be found online in the complete document.

Epidemiology and clinical features of Streptococcus pyogenes bloodstream infections in children in Madrid, Spain.

Studies have shown increased invasive Group A Streptococcus (GAS) disease, including bloodstream infections (GAS-BSI). However, the epidemiological data of GAS-BSI are limited in children. We aimed to describe GAS-BSI in children in Madrid, over 13 years (2005-2017). Multicenter retrospective cohort study from 16 hospitals from Madrid, Spain. Epidemiology, symptomatology, laboratory, treatment, and outcome of GAS-BSI in children ≤ 16 years were analyzed. 109 cases of GAS-BSI were included, with incidence rate of 4.3 episodes/100,000 children attended at the emergency department/year. We compared incidence between two periods (P1: 2005-June 2011 vs P2: July 2011-2017) and observed a non-significant increase along the study period (annual percentage change: + 6.0% [95%CI: -2.7, + 15.4]; p = 0.163). Median age was 24.1 months (IQR: 14.0-53.7), peaking during the first four years of life (89/109 cases; 81.6%). Primary BSI (46.8%), skin and soft tissue (21.1%), and osteoarticular infections (18.3%) were the most common syndromes. We compared children with primary BSI with those with a known source and observed that the former had shorter hospital stay (7 vs. 13 days; p = 0.003) and received intravenous antibiotics less frequently (72.5% vs. 94.8%; p = 0.001) and for shorter duration of total antibiotic therapy (10 vs. 21 days; p = 0.001). 22% of cases required PICU admission. Factors associated with severity were respiratory distress, pneumonia, thrombocytopenia, and surgery, but in multivariate analysis, only respiratory distress remained significant (adjusted OR:9.23 [95%CI: 2.16-29.41]). Two children (1.8%) died.   Conclusion: We observed an increasing, although non-significant, trend of GAS-BSI incidence within the study. Younger children were more frequently involved, and primary BSI was the most common and less severe syndrome. PICU admission was frequent, being respiratory distress the main risk factor. What is known: • In recent decades, several reports have shown a worldwide increase in the incidence of invasive Group A streptococcal disease (GAS), including bloodstream infection (BSI). Recently, there have been a few reports showing an increase in severity as well. • There needs to be more information on the epidemiology in children since most studies predominantly include adults. What is new: • This study, carried out in children with GAS-BSI in Madrid, shows that GAS-BSI affects mostly younger children, with a broad spectrum of manifestations, needing PICU admission frequently. Respiratory distress was the leading risk factor for severity, whereas primary BSI seemed to be less severe. • We observed an increasing, although non-significant, trend of GAS-BSI incidence in recent years (2005-2017).

Acute Epstein-Barr virus infection: Diagnostic challenge in young children, risk factors for hospitalisation and cytomegalovirus co-detection.

AIM: Acute Epstein-Barr virus (aEBV) and cytomegalovirus (CMV) infections frequently have similar manifestations. We aim to evaluate the characteristics of aEBV infection, risk factors for hospitalisation and differences according to CMV IgM detection (EBV-CMV co-detection) in children. METHODS: Retrospective, single-centre study including patients <16 years diagnosed with aEBV infection (positive anti-EBV IgM/Paul-Bunnell test and acute symptomatology). EBV-CMV co-detection was defined as positive CMV IgM. Factors associated with age, hospitalisation and EBV-CMV co-detection were analysed in a multivariate analysis. RESULTS: A total of 149 patients were included (median age 4.6 years). Most frequent manifestations were fever (77%), cervical lymphadenopathy (64%) and elevated liver enzymes (54%). Younger children had lower rate of positive Paul-Bunnell test (35% vs. 87%; p < 0.01), but higher rate of EBV-CMV co-detection (54% vs. 29%; p = 0.03). These children tended to have less typical symptoms of infectious mononucleosis and higher hospitalisation rate. The overall antibiotic prescription was 49%. Hospitalisation (27 children; 18%) was independently associated with prior antibiotic therapy and anaemia. Sixty-two cases (42%) had EBV-CMV co-detection, which was independently associated with elevated liver enzymes and younger age. CONCLUSION: In this study, younger children with aEBV infection presented more frequently with atypical clinical symptoms, had higher EBV-CMV co-detection rates and were more often hospitalised. Hospitalisation was associated with prior antibiotic prescription.

The role of the T-cell mediated immune response to Cytomegalovirus infection in intrauterine transmission.

INTRODUCTION: Prognostic markers for fetal transmission of Cytomegalovirus (CMV) infection during pregnancy are poorly understood. Maternal CMV-specific T-cell responses may help prevent fetal transmission and thus, we set out to assess whether this may be the case in pregnant women who develop a primary CMV infection. METHODS: A multicenter prospective study was carried out at 8 hospitals in Spain, from January 2017 to April 2020. Blood samples were collected from pregnant women at the time the primary CMV infection was diagnosed to assess the T-cell response. Quantitative analysis of interferon producing specific CMV-CD8+/CD4+ cells was performed by intracellular cytokine flow cytometry. RESULTS: In this study, 135 pregnant women with a suspected CMV infection were evaluated, 60 of whom had a primary CMV infection and samples available. Of these, 24 mothers transmitted the infection to the fetus and 36 did not. No association was found between the presence of specific CD4 or CD8 responses against CMV at the time maternal infection was diagnosed and the risk of fetal transmission. There was no transmission among women with an undetectable CMV viral load in blood at diagnosis. CONCLUSIONS: In this cohort of pregnant women with a primary CMV infection, no association was found between the presence of a CMV T-cell response at the time of maternal infection and the risk of intrauterine transmission. A detectable CMV viral load in the maternal blood at diagnosis of the primary maternal infection may represent a relevant biomarker associated with fetal transmission.

Guideline for management of septic arthritis in native joints (SANJO).

This clinical guideline is intended for use by orthopedic surgeons and physicians who care for patients with possible or documented septic arthritis of a native joint (SANJO). It includes evidence and opinion-based recommendations for the diagnosis and management of patients with SANJO.

Colchicine as rescue treatment in two pediatric patients with chronic recurrent multifocal osteomyelitis (CRMO).

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare idiopathic autoinflammatory bone disease characterised by noninfective inflammation of bones. Diagnostic approach is challenging and requires exclusion of other causes such as malignancies or infections. Nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids are usually applied as first-line therapy in CRMO patients; however, some cases require more intensive therapy with second-line agents to control disease activity. We hereby describe the use of colchicine as a nonconventional second-line disease-modifying antirheumatic drug in two pediatric patients with CRMO refractory to NSAIDs and corticosteroids. Our data indicate that colchicine might prove an important area for future research as a potential therapeutic option with easy administration, low cost, and a good safety profile in CRMO patients refractory to first-line therapy.

Treatments for multi-system inflammatory syndrome in children - discharge, fever, and second-line therapies.

Scarce evidence exists about the best treatment for multi-system inflammatory syndrome (MIS-C). We analyzed the effects of steroids, intravenous immunoglobulin (IVIG), and their combination on the probability of discharge over time, the probability of switching to second-line treatment over time, and the persistence of fever 2 days after treatment. We did a retrospective study to investigate the effect of different treatments on children with MIS-C from 1 March 2020 to 1 June 2021. We estimated the time-to-event probability using a Cox model weighted by propensity score to balance the baseline characteristics. Thirty of 132 (22.7%) patients were initially treated with steroids alone, 29/132 (21.9%) with IVIG alone, and 73/132 (55%) with IVIG plus steroids. The probability of early discharge was higher with IVIG than with IVIG plus steroids (hazard ratio [HR] 1.65, 95% CI 1.11-2.45, p = 0.013), but with a higher probability of needing second-line therapy compared to IVIG plus steroids (HR 3.05, 95% CI 1.12-8.25, p = 0.028). Patients on IVIG had a higher likelihood of persistent fever than patients on steroids (odds ratio [OR] 4.23, 95% CI 1.43-13.5, p = 0.011) or on IVIG plus steroids (OR 4.4, 95% CI 2.05-9.82, p < 0.001). No differences were found for this endpoint between steroids or steroids plus IVIG.    Conclusions: The benefits of each approach may vary depending on the outcome assessed. IVIG seemed to increase the probability of earlier discharge over time but also of needing second-line treatment over time. Steroids seemed to reduce persistent fever, and combination therapy reduced the need for escalating treatment. What is Known: • Steroids plus intravenous immunoglobulin, compared with intravenous immunoglobulin alone for multi-system inflammatory syndrome (MIS-C) might reduce the need for hemodynamic support and the duration of fever, but the certainty of the evidence is low. What is New: • Intravenous immunoglobulin, steroids, and their combination for MIS-C may have different outcomes. • In this study, intravenous immunoglobulin increased the probability of discharge over time, steroids reduced persistent fever, while combination therapy reduced the need for second-line treatments.

Clinical Phenotype of Respiratory Syncytial Virus Bronchiolitis before and during the Coronavirus Disease 2019 Pandemic.

OBJECTIVE: The main objective of this report was to comprehensively analyze the clinical characteristics of children hospitalized with respiratory syncytial virus (RSV) infections in 2021 during the coronavirus disease 2019 (COVID-19) pandemic and to compare them with those in the five previous RSV seasons. We hypothesized that the clinical and demographic features of children hospitalized with RSV infection in 2021 were different from those hospitalized in previous respiratory seasons. STUDY DESIGN: In this retrospective observational study, children younger than 2 years hospitalized with RSV bronchiolitis from January 1, 2015, to December 31, 2021, at the Department of Pediatrics of the Hospital Gregorio Marañón, Madrid, Spain, were included. We compared the clinical characteristics of children hospitalized with RSV bronchiolitis in the five seasons before the COVID-19 pandemic and during the subsequent off-seasonal surge of RSV infections. RESULTS: We found a significant reduction in hospitalizations for RSV bronchiolitis during the usual winter epidemic period due to the COVID-19 pandemic. Children hospitalized with RSV infection in 2021, during the COVID-19 pandemic, were older than children hospitalized in the prepandemic period (2015-2020; 4.0 [1.6-9.2] vs. 3 [1.5-6.5] months; p < 0.01). We also found shorter duration of oxygen days during the COVID-19 period compared with previous respiratory seasons (3 [2-5] vs. 4 [2-6] days; p = 0.02). CONCLUSION: The COVID-19 pandemic modified the RSV seasonality with a significant reduction in RSV hospitalizations during the expected 2020-2021 season and a reappearance of RSV 7 months later than expected. We also found changes in the median age of children with RSV bronchiolitis during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic compared with the prepandemic RSV seasons and shorter duration of oxygen days suggesting a modest reduction in disease severity. We hypothesize that this observation reflects the lack of RSV circulation in the previous months (April 2020-March 2021), with a larger pool of vulnerable infants that had not been previously infected. KEY POINTS: · The COVID-19 pandemic shifted RSV seasonality.. · RSV children hospitalized during the pandemic were older.. · Modest reduction in disease severity was observed during the pandemic..

Accuracy of Xpert Ultra for the diagnosis of paediatric tuberculosis in a low TB burden country: a prospective multicentre study.

INTRODUCTION: Childhood pulmonary tuberculosis (TB) remains a diagnostic challenge. This study aimed to evaluate the performance of Xpert Ultra for the diagnosis of pulmonary TB in children in a low TB prevalence setting. METHODS: Prospective, multicentre, diagnostic accuracy study. Children with clinical or radiological suspicion of pulmonary TB were recruited at 11 paediatric units in Spain. Up to three gastric or sputum specimens were taken on 3 consecutive days, and analysed by Xpert MTB/RIF, Xpert Ultra and culture in parallel. RESULTS: 86 children were included (median age 4.9 years, IQR 2.0-10.0; 51.2% male). The final diagnosis was pulmonary TB in 75 patients (87.2%); 33 (44.0%) were microbiologically confirmed. A total of 219 specimens, comprising gastric aspirates (n=194; 88.6%) and sputum specimens (n=25; 11.4%), were analysed. Using culture as reference standard and comparing individual specimens, the sensitivity was 37.8% (14/37) for Xpert MTB/RIF and 81.1% (30/37) for Xpert Ultra (p<0.001); specificity was 98.4% (179/182) and 93.4% (170/182), respectively (p=0.02). In the per-patient analysis, considering positive results on any specimen, the sensitivity was 42.9% (9/21) for Xpert MTB/RIF and 81.0% for Xpert Ultra (17/21, p=0.01); specificity was 96.9% (63/65) and 87.7% (57/65, p=0.07), respectively. CONCLUSIONS: In children with pulmonary TB in a low burden setting, Xpert Ultra has significantly higher sensitivity than the previous generation of Xpert assay and only marginally lower specificity. Therefore, in children undergoing evaluation for suspected pulmonary TB, Xpert Ultra should be used in preference to Xpert MTB/RIF whenever possible.

Chronic Q Fever as Recurrent Osteoarticular Infection in Children: Case Report and Literature Review.

Q fever osteomyelitis has been rarely reported in children. This infection has an unclear pathophysiology and the optimal therapy is unknown. We report a 2-year-old girl with Coxiella burnetti recurrent multifocal osteomyelitis: femur, metatarsal, cuneiform, and calcaneus. We highlight the complicated diagnosis and management of this case and the importance of considering Q fever in children with chronic-recurrent multifocal osteomyelitis.

SARS-CoV2 Infection During Pregnancy Causes Persistent Immune Abnormalities in Women Without Affecting the Newborns.

SARS-CoV2 infection in pregnancy and exposed newborns is poorly known. We performed a longitudinal analysis of immune system and determined soluble cytokine levels in pregnant women infected with SARS-CoV2 and in their newborns. Women with confirmed SARS-CoV2 infection and their exposed uninfected newborns were recruited from Hospital General Universitario Gregorio Marañón. Peripheral blood mononuclear cells (PBMCs), cord cells and plasma were collected at birth and 6 months later. Immunophenotyping of natural killer (NK), monocytes and CD4/CD8 T-cells were studied in cryopreserved PBMCs and cord cells by multiparametric flow cytometry. Up to 4 soluble pro/anti-inflammatory cytokines were assessed in plasma/cord plasma by ELISA assay. SARS-CoV2-infected mothers and their newborns were compared to matched healthy non-SARS-CoV2-infected mothers and their newborns. The TNFα and IL-10 levels of infected mothers were higher at baseline than those of healthy controls. Infected mothers showed increased NK cells activation and reduced expression of maturation markers that reverted after 6 months. They also had high levels of Central Memory and low Effector Memory CD4-T cell subsets. Additionally, the increased CD4- and CD8-T cell activation (CD154 and CD38) and exhaustion (TIM3/TIGIT) levels at baseline compared to controls remained elevated after 6 months. Regarding Treg cells, the levels were lower at infected mothers at baseline but reverted after 6 months. No newborn was infected at birth. The lower levels of monocytes, NK and CD4-T cells observed at SARS-CoV2-exposed newborns compared to unexposed controls significantly increased 6 months later. In conclusion, SARS-CoV2 infection during pregnancy shows differences in immunological components that could lead newborns to future clinical implications after birth. However, SARS-CoV2 exposed 6-months-old newborns showed no immune misbalance, whereas the infected mothers maintain increased activation and exhaustion levels in T-cells after 6 months.

Oral Versus Intravenous Antibiotics for Pediatric Osteoarticular Infection: When and to Whom?

BACKGROUND: Osteoarticular infections (OAIs) are typically treated initially with intravenous antibiotics. The objective of this study was to evaluate whether an exclusive oral treatment in selected children may be appropriate. METHODS: The Spanish Network of Osteoarticular Infections is a nationwide multicenter registry comprising 37 hospitals in Spain. The registry prospectively includes clinical characteristics and outcome of children with OAI. One of the hospitals from RioPed offers oral treatment to children meeting certain criteria. Patients were classified into 2 groups. Group 1: management with initial intravenous antibiotic therapy. Group 2: patients exclusively treated with oral antibiotics. A comparison between the 2 groups was performed. RESULTS: We compared 893 children who initially received intravenous antibiotics (group 1) with 64 children who received exclusively oral therapy (group 2). Patients from group 2 were younger (33.9 vs. 20.3 months; P = 0.001), had a lower percentage of Staphylococcus aureus (23.3% vs. 3.1%; P < 0.001), a higher proportion of Kingella kingae (12.1% vs. 28.1%; P = 0.001), higher erythrocyte sedimentation rate/C-reactive protein (CRP) ratio (1.4 interquartile range 0.6-3.6 vs. 3.3 interquartile range 1.7-5.7; P < 0.001) and showed lower rate of fever (63% vs. 48.8%; P = 0.024) than in group 1. Complications were not found in group 2. CONCLUSIONS: An exclusively oral administration could be a safe option in selected patients with OAI. Low-risk criteria are proposed: good general condition, no underlying disease, 6 months to 3 years old, appropriate oral tolerance, C-reactive protein <80 mg/L, erythrocyte sedimentation rate/C-reactive protein ratio ≥0.67, no skin injury, no recent surgery, no cervical spondylodiscitis and no local complications at onset.

Staphylococcus aureus Community-acquired Pneumonia in Children After 13-Valent Pneumococcal Vaccination (2008-2018): Epidemiology, Clinical Characteristics and Outcomes.

BACKGROUND: The epidemiology of community-acquired pneumonia (CAP) has changed, influenced by sociosanitary conditions and vaccination status. We aimed to analyze the recent epidemiology of bacterial CAP in hospitalized children in a setting with high pneumococcal vaccination coverage and to describe the clinical characteristics of pediatric Staphylococcus aureus CAP. METHODS: Children <17 years old hospitalized from 2008 to 2018 with bacterial CAP in 5 tertiary hospitals in Spain were included. Cases with pneumococcal CAP were randomly selected as comparative group following a case-control ratio of 2:1 with S. aureus CAP. RESULTS: A total of 313 bacterial CAP were diagnosed: Streptococcus pneumoniae CAP (n = 236, 75.4%), Streptococcus pyogenes CAP (n = 43, 13.7%) and S. aureus CAP (n = 34, 10.9%). Throughout the study period, the prevalence of S. pyogenes increased (annual percentage change: +16.1% [95% CI: 1.7-32.4], P = 0.031), S. pneumoniae decreased (annual percentage change: -4.4% [95 CI: -8.8 to 0.2], P = 0.057) and S. aureus remained stable. Nine isolates of S. aureus (26.5%) were methicillin-resistant. Seventeen cases (50%) with S. aureus CAP had some pulmonary complication and 21 (61.7%) required intensive care. S. pneumoniae CAP showed a trend toward higher prevalence of pulmonary complications compared with S. aureus CAP (69.1% vs. 50.0%, P = 0.060), including higher frequency of pulmonary necrosis (32.4% vs. 5.9%, P = 0.003). CONCLUSIONS: The incidence of S. aureus CAP in children remained stable, whereas the prevalence of pneumococcal CAP decreased and S. pyogenes CAP increased. Patients with S. aureus presented a high frequency of severe outcomes, but a lower risk of pulmonary complications than patients with S. pneumoniae.

Risk-score based strategy to minimize antibiotic exposure in children with sickle cell disease and fever.

Severe bacterial infections (SBI) have become less frequent in children with sickle cell disease (SCD) in the last decades. However, because of their potential risk of SBI, they usually receive empirical therapy with broad-spectrum antibiotics when they develop fever and are hospitalized in many cases. We performed a prospective study including 79 SCD patients with fever [median age 4.1 (1.7-7.5) years, 78.5% males; 17 of the episodes were diagnosed with SBI and 4 of them were confirmed] and developed a risk score for the prediction of SBI. The optimal score included CRP > 3 mg/dl, IL-6 > 125 pg/ml and hypoxemia, with an AUC of 0.91 (0.83-0.96) for the prediction of confirmed SBI and 0.86 (0.77-0.93) for possible SBI. We classified the patients in 3 groups: low, intermediate and high risk of SBI. Our risk-score-based management proposal could help to safely minimize antibiotic treatments and hospital admissions in children with SCD at low risk of SBI.

Interleukin 6 as a marker of severe bacterial infection in children with sickle cell disease and fever: a case-control study.

BACKGROUND: Etiological diagnosis of fever in children with sickle cell disease (SCD) is often challenging. The aim of this study was to analyze the pattern of inflammatory biomarkers in SCD febrile children and controls, in order to determine predictors of severe bacterial infection (SBI). METHODS: A prospective, case-control study was carried out during 3 years, including patients younger than 18 years with SCD and fever (cases) and asymptomatic steady-state SCD children (controls). Clinical characteristics and laboratory parameters, including 10 serum proinflammatory cytokines (IL-1ß, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-17a, IFN-γ and TNF-α) and comparisons among study subgroups were analyzed. RESULTS: A total of 137 patients (79 cases and 58 controls) were included in the study; 78.5% males, median age 4.1 (1.7-7.5) years. Four cases were diagnosed with SBI, 41 viral infection (VI), 33 no proven infection (NPI) and 1 bacterial-viral coinfection (the latter excluded from the subanalyses). IL-6 was significantly higher in patients with SBI than in patients with VI or NPI (163 vs 0.7 vs 0.7 pg/ml, p < 0.001), and undetectable in all controls. The rest of the cytokines analyzed did not show any significant difference. The optimal cut-off value of IL-6 for the diagnosis of SBI was 125 pg/mL, with high PPV and NPV (PPV of 100% for a prevalence rate of 5, 10 and 15% and NPV of 98.7%, 97.3% and 95.8% for those prevalences rates, respectively). CONCLUSION: We found that IL-6 (with a cut-off value of 125 pg/ml) was an optimal marker for SBI in this cohort of febrile SCD children, with high PPV and NPV. Therefore, given its rapid elevation, IL-6 may be useful to early discriminate SCD children at risk of SBI, in order to guide their management.