Serious Bacterial Infections in Young Febrile Infants With Positive Urinalysis Results.

It is unknown whether febrile infants 29 to 60 days old with positive urinalysis results require routine lumbar punctures for evaluation of bacterial meningitis. OBJECTIVE: To determine the prevalence of bacteremia and/or bacterial meningitis in febrile infants ≤60 days of age with positive urinalysis (UA) results. METHODS: Secondary analysis of a prospective observational study of noncritical febrile infants ≤60 days between 2011 and 2019 conducted in the Pediatric Emergency Care Applied Research Network emergency departments. Participants had temperatures ≥38°C and were evaluated with blood cultures and had UAs available for analysis. We report the prevalence of bacteremia and bacterial meningitis in those with and without positive UA results. RESULTS: Among 7180 infants, 1090 (15.2%) had positive UA results. The risk of bacteremia was higher in those with positive versus negative UA results (63/1090 [5.8%] vs 69/6090 [1.1%], difference 4.7% [3.3% to 6.1%]). There was no difference in the prevalence of bacterial meningitis in infants ≤28 days of age with positive versus negative UA results (∼1% in both groups). However, among 697 infants aged 29 to 60 days with positive UA results, there were no cases of bacterial meningitis in comparison to 9 of 4153 with negative UA results (0.2%, difference -0.2% [-0.4% to -0.1%]). In addition, there were no cases of bacteremia and/or bacterial meningitis in the 148 infants ≤60 days of age with positive UA results who had the Pediatric Emergency Care Applied Research Network low-risk blood thresholds of absolute neutrophil count <4 × 103 cells/mm3 and procalcitonin <0.5 ng/mL. CONCLUSIONS: Among noncritical febrile infants ≤60 days of age with positive UA results, there were no cases of bacterial meningitis in those aged 29 to 60 days and no cases of bacteremia and/or bacterial meningitis in any low-risk infants based on low-risk blood thresholds in both months of life. These findings can guide lumbar puncture use and other clinical decision making.

A Clinical Prediction Rule to Identify Febrile Infants 60 Days and Younger at Low Risk for Serious Bacterial Infections.

Importance: In young febrile infants, serious bacterial infections (SBIs), including urinary tract infections, bacteremia, and meningitis, may lead to dangerous complications. However, lumbar punctures and hospitalizations involve risks and costs. Clinical prediction rules using biomarkers beyond the white blood cell count (WBC) may accurately identify febrile infants at low risk for SBIs. Objective: To derive and validate a prediction rule to identify febrile infants 60 days and younger at low risk for SBIs. Design, Setting, and Participants: Prospective, observational study between March 2011 and May 2013 at 26 emergency departments. Convenience sample of previously healthy febrile infants 60 days and younger who were evaluated for SBIs. Data were analyzed between April 2014 and April 2018. Exposures: Clinical and laboratory data (blood and urine) including patient demographics, fever height and duration, clinical appearance, WBC, absolute neutrophil count (ANC), serum procalcitonin, and urinalysis. We derived and validated a prediction rule based on these variables using binary recursive partitioning analysis. Main Outcomes and Measures: Serious bacterial infection, defined as urinary tract infection, bacteremia, or bacterial meningitis. Results: We derived the prediction rule on a random sample of 908 infants and validated it on 913 infants (mean age was 36 days, 765 were girls [42%], 781 were white and non-Hispanic [43%], 366 were black [20%], and 535 were Hispanic [29%]). Serious bacterial infections were present in 170 of 1821 infants (9.3%), including 26 (1.4%) with bacteremia, 151 (8.3%) with urinary tract infections, and 10 (0.5%) with bacterial meningitis; 16 (0.9%) had concurrent SBIs. The prediction rule identified infants at low risk of SBI using a negative urinalysis result, an ANC of 4090/µL or less (to convert to ×109 per liter, multiply by 0.001), and serum procalcitonin of 1.71 ng/mL or less. In the validation cohort, the rule sensitivity was 97.7% (95% CI, 91.3-99.6), specificity was 60.0% (95% CI, 56.6-63.3), negative predictive value was 99.6% (95% CI, 98.4-99.9), and negative likelihood ratio was 0.04 (95% CI, 0.01-0.15). One infant with bacteremia and 2 infants with urinary tract infections were misclassified. No patients with bacterial meningitis were missed by the rule. The rule performance was nearly identical when the outcome was restricted to bacteremia and/or bacterial meningitis, missing the same infant with bacteremia. Conclusions and Relevance: We derived and validated an accurate prediction rule to identify febrile infants 60 days and younger at low risk for SBIs using the urinalysis, ANC, and procalcitonin levels. Once further validated on an independent cohort, clinical application of the rule has the potential to decrease unnecessary lumbar punctures, antibiotic administration, and hospitalizations.

Prehospital Analgesic Administration by Parents for Pain Relief in Children.

PURPOSE: Undertreatment of pain by caregivers before presentation to the pediatric emergency department (ED) has been well documented. What has yet to be elucidated are the reasons why caregivers fail to adequately treat pain before arrival in the ED and whether there are differences based on ethnic background or age of the child. The objectives of this study were to determine the barriers to giving pain medication for injuries before ED arrival and to determine if there are any ethnic- or age-related variations to giving pain relief at home. METHODS: This prospective descriptive study was conducted in the ED at a tertiary care, freestanding children's hospital with a current annual census of approximately 80,000. An anonymous prospective questionnaire was given to caregivers of children between 2 and 17 years of age presenting to the ED between August 2013 and September, 2014. The study population was obtained as a convenience sample. All were self-referred with chief complaints of head, ear, or extremity pain. The questionnaire asked about pain medications and doses given at home as well as the reasons parents gave medication or refused to give pain medication before arrival. Charts were then abstracted to obtain demographic information and care received in the ED. RESULTS: A total of 154 (45.6%) of the 338 patients enrolled did not receive pain relief before coming to the ED. There were no differences in pain medication received at home based on ethnicity (P = 0.423) or age (P = 0.580). Parents could choose from a list of multiple reasons as to why pain medications were given and/or free text their own answer. The main reasons given by parents were that the accident did not happen at home (28.6%) and that they did not have time to give pain relief before coming to the ED (13%). Other common answers were "had no pain relievers at home" (12.4%) or "afraid it would be wrong/harmful/did not want to mask symptoms" (9.2%). Seventeen parents responded that their child did not complain of pain. Overall, only 28.1% of participants stated lack of pain medications at home. CONCLUSIONS: In this study, approximately half of all children receive an analgesic for their painful condition before coming to the ED. Continued education regarding pain relief before coming to the ED is needed. Future studies will focus on educating parents to provide analgesia at home.

Missed Fractures in Infants Presenting to the Emergency Department With Fussiness.

OBJECTIVES: The aim of this study was to evaluate incidence of prior fussy emergency visits in infants with subsequently diagnosed fractures suggestive of abuse. METHODS: This was a retrospective chart review of infants younger than 6 months who presented to the pediatric emergency department (ED) between January 1, 2006, and December 31, 2011. Inclusion criteria included age 0 to 6 months, discharge diagnosis including "fracture," "broken" (or break), or "trauma" or any child abuse diagnosis or chief complaint of "fussy" or "crying" as documented in the electronic medical record by the triage nurse. RESULTS: Three thousand seven hundred thirty-two charts were reviewed, and 279 infants with fractures were identified. Eighteen (6.5%) of 279 infants had a prior ED visit for fussiness without an obvious source. Of these, 2 had a witnessed event causing their fracture, and therefore the fracture was not considered concerning for abuse. The remaining 16 had fractures concerning for abuse. Mean age was 2.5 (SD, 1.2) months. Fifteen (83%) of 18 infants were 3 months or younger at the time of the fussy visit. The mean interval between the first and second ED visits was 27 days (median, 20 days). Thirty-nine percent were evaluated by a pediatric emergency medicine-trained physician during their initial fussy visit, whereas 78% were evaluated by pediatric emergency medicine-trained physician during their subsequent visit. Most common injuries were multiple types of fractures followed by extremity and rib fractures. CONCLUSIONS: Fractures concerning for child abuse are an important cause of unexplained fussiness in infants presenting to the pediatric ED. A high index of suspicion is essential for prompt diagnosis and likely prevention of other abuse.

Clinical Presentation and Outcomes Associated with Different Treatment Modalities for Pediatric Bark Scorpion Envenomation.

INTRODUCTION: Scorpion envenomation is potentially life-threatening and affects children in the Southwestern USA. An FDA-approved antivenom is available, but its high cost has led to use of off-label antivenom dosing or supportive care alone as alternatives to FDA-recommended dosing. This study sought to determine whether treatment approach influences outcomes in envenomated children. METHODS: A retrospective cohort study of children with grade III or IV scorpion envenomation evaluated in Phoenix Children's Hospital ED between September 1, 2011, and March 31, 2014. Patients were grouped based on treatment: group 1, supportive care only; group 2, FDA-recommended dosing (3-vial initial dose); group 3, "off label" dosing (1-2 vial initial dose). Primary outcomes were ED length of stay and hospital admission. Secondary outcomes were mechanical ventilation and aspiration pneumonia. RESULTS: One hundred fifty-six patients were included with 58 patients in group 1, 16 patients in group 2, and 82 patients in group 3. Group 1 was significantly older than the antivenom groups (p < 0.001), and group 2 was younger than group 3 (p = 0.024). Envenomation grade was also different, with group 1 having fewer grade IV then groups 2 and 3 (p < 0.001). Three percent of group 1, 56 % of group 2, and 28 % of group 3 had respiratory distress (p < 0.001). ED LOS was not significantly different between groups. Hospital admission occurred in 3.4 % group 1, no group 2, and 8.5 % group 3 patients. Two intubations and two aspirations occurred in group 3. CONCLUSIONS: In this study, clinical presentation appeared to influence treatment. Groups that received antivenom had a higher envenomation grade than the group that received supportive care. The FDA-recommended dosing group was younger and had more respiratory distress than those treated with initial doses of 1-2 vials. Outcomes were not significantly different between groups. Prospective studies may identify the ideal population for each treatment approach.

Association of RNA Biosignatures With Bacterial Infections in Febrile Infants Aged 60 Days or Younger.

IMPORTANCE: Young febrile infants are at substantial risk of serious bacterial infections; however, the current culture-based diagnosis has limitations. Analysis of host expression patterns ("RNA biosignatures") in response to infections may provide an alternative diagnostic approach. OBJECTIVE: To assess whether RNA biosignatures can distinguish febrile infants aged 60 days or younger with and without serious bacterial infections. DESIGN, SETTING, AND PARTICIPANTS: Prospective observational study involving a convenience sample of febrile infants 60 days or younger evaluated for fever (temperature >38° C) in 22 emergency departments from December 2008 to December 2010 who underwent laboratory evaluations including blood cultures. A random sample of infants with and without bacterial infections was selected for RNA biosignature analysis. Afebrile healthy infants served as controls. Blood samples were collected for cultures and RNA biosignatures. Bioinformatics tools were applied to define RNA biosignatures to classify febrile infants by infection type. EXPOSURE: RNA biosignatures compared with cultures for discriminating febrile infants with and without bacterial infections and infants with bacteremia from those without bacterial infections. MAIN OUTCOMES AND MEASURES: Bacterial infection confirmed by culture. Performance of RNA biosignatures was compared with routine laboratory screening tests and Yale Observation Scale (YOS) scores. RESULTS: Of 1883 febrile infants (median age, 37 days; 55.7% boys), RNA biosignatures were measured in 279 randomly selected infants (89 with bacterial infections-including 32 with bacteremia and 15 with urinary tract infections-and 190 without bacterial infections), and 19 afebrile healthy infants. Sixty-six classifier genes were identified that distinguished infants with and without bacterial infections in the test set with 87% (95% CI, 73%-95%) sensitivity and 89% (95% CI, 81%-93%) specificity. Ten classifier genes distinguished infants with bacteremia from those without bacterial infections in the test set with 94% (95% CI, 70%-100%) sensitivity and 95% (95% CI, 88%-98%) specificity. The incremental C statistic for the RNA biosignatures over the YOS score was 0.37 (95% CI, 0.30-0.43). CONCLUSIONS AND RELEVANCE: In this preliminary study, RNA biosignatures were defined to distinguish febrile infants aged 60 days or younger with vs without bacterial infections. Further research with larger populations is needed to refine and validate the estimates of test accuracy and to assess the clinical utility of RNA biosignatures in practice.

Outcomes of arterial vascular extremity trauma in pediatric patients.

BACKGROUND: Vascular trauma in children, although rare, carries significant risk for repair. Here we report outcomes from a single trauma center for children with extremity vascular trauma, proximal to the digits. METHODS: Retrospective chart review of patients less than age 18years with an acute, non-iatrogenic traumatic arterial vascular injury of the upper and/or lower extremity between January 2008 and December 2013. Abstracted patient demographics, injury characteristics, surgical management, and disposition were summarized and compared with nonparametric methods. RESULTS: 23 children comprised the study cohort: median age of 8years (IQR: 4.6-12), 61% (n=14) males, 100% survival. Penetrating injuries were the predominate mechanism (n=17, 74%). The median time to presentation was 154min (IQR: 65-330). Acute operations for revascularization included a primary repair (n=15, 65%) or reversed vein graft (n=7, 30%). Fasciotomies were done for 3 (13%) patients. Three amputations were done for failed revascularization. Upper extremity vascular injury (n=15, 65%) was more common. The rate of associated extremity fracture was similar between upper (21%) and lower (33%) extremities (p=0.643). Eight (35%) patients required additional surgery most commonly for debridement, washouts and dressing changes. Three patients' hospital stays were complicated by infection. Impaired function was the most common short- and long-term complication (60%, 75%). CONCLUSION: Pediatric vascular injuries are commonly associated with penetrating injuries and male gender and occurred more frequently in the upper extremities. Overall patency rates after repair were 87%. Fasciotomies were done in 13% of patients, and the overall surgical amputation rate was 13%. There was no mortality in this cohort; however, multiple operations are commonly required, including the return to OR for washouts, debridements and dressing changes. The most common short- and long-term complication was impaired function. Overall good results are achievable in pediatric vascular trauma treated with revascularization.

Outcomes of digital artery revascularization in pediatric trauma.

BACKGROUND: Digit amputation is rare in pediatric trauma but can lead to functional morbidity. The true incidence of digital arterial injury is lacking in the literature, and revascularization techniques are not well-described. METHODS: Retrospective review of a pediatric trauma registry identified patients with a digital artery injury between July 2008 and December 2013. Isolated vein injuries and arterial injuries proximal to the digits were excluded. Descriptive statistics were used. RESULTS: Twenty-five subjects met inclusion. Most were male (n=16; 64%) and the median age was 6.8 (IQR: 2.8, 11.1) years. The most common blunt (n=12) trauma was struck/crushed by object (n=4; 33%) and the most common penetrating (n=13) trauma was because of glass (n=9; 69%). All subjects were managed operatively. Initial operations for arterial repair were primary arterial repair (15; 20%), vein graft (7; 28%), thrombectomy (1; 4%), and amputation (1; 4%). Twelve patients (48%) had reported complications at initial follow-up, but only two (8%) had long-term (>24weeks) sequelae. CONCLUSION: Digital artery injury is rare among pediatric traumas. Functional outcomes after digital artery revascularization are favorable. Primary repair can successfully manage these injuries and vein grafting appears to be a suitable alternative when primary repair is not feasible.

Procalcitonin as a Marker of Bacteremia in Patients With Fever and Acute Lymphoblastic Leukemia.

BACKGROUND: Children undergoing treatment for acute lymphoblastic leukemia (ALL) often present to the emergency department (ED) with a fever. They are at high risk of bacteremia secondary to being immunocompromised. Recent reports indicate that procalcitonin (PCT) is a useful marker of bacteremia in children. OBJECTIVE: Our objective was to evaluate the clinical utility of PCT as a rapid marker of bacteremia in children with ALL presenting to the ED with a fever. In addition, we compared the results of PCT with white blood cell (WBC) count, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). METHODS: Retrospective chart reviews were conducted of 492 patients with a total of 735 visits presenting to the ED from January 2009 to June 2012 with fever and a history of ALL where a PCT and a blood culture (BC) were obtained,. Positive BCs determined to be contaminants were excluded. The predictive powers of PCT, WBC, ESR, and CRP for bacteremia were evaluated using the area under the receiver operating characteristic curve with 95% confidence intervals (CI). In addition, each of the 4 markers were also examined in a logistic regression model as a potential predictor of the BC result. RESULTS: A total of 735 PCT values were correlated with BC results. There were 76 (10.3%) true-positive BCs. The area under the receiver operating characteristic curve was 0.729 (95% CI, 0.661-0.792) for PCT, 0.685 (95% CI, 0.531-0.823) for ESR, 0.622 (95% CI, 0.460-0.796) for CRP, and 0.567 (95% CI, 0.483-0.649) for WBC. When logistic regression was used, the transformation log PCT was significantly associated with BC result whereas each of the other 3 markers, after appropriate transformation to remove heavy skewness, was not significant (all P > 0.1). A doubling of PCT was associated with an odds ratio of 1.32 for positive BCs (95% CI, 1.15-1.53). CONCLUSIONS: Procalcitonin value was significantly associated with positive BC (P < 0.0001). The diagnostic performance of PCT was better than the other markers of inflammation. Its use in the ED in a select population of patients may be of significant value in identifying bacteremia. This has the potential to lead to a decrease in unwarranted use of antibiotics, hospital length of stay, and health care expenditures.

Reactivation of multiple viruses in patients with sepsis.

A current controversy is whether patients with sepsis progress to an immunosuppressed state. We hypothesized that reactivation of latent viruses occurred with prolonged sepsis thereby providing evidence of clinically-relevant immunosuppression and potentially providing a means to serially-monitor patients' immune status. Secondly, if viral loads are markedly elevated, they may contribute to morbidity and mortality. This study determined if reactivation of herpesviruses, polyomaviruses, and the anellovirus TTV occurred in sepsis and correlated with severity. Serial whole blood and plasma samples from 560 critically-ill septic, 161 critically-ill non-septic, and 164 healthy age-matched patients were analyzed by quantitative-polymerase-chain-reaction for cytomegalovirus (CMV), Epstein-Barr (EBV), herpes-simplex (HSV), human herpes virus-6 (HHV-6), and TTV. Polyomaviruses BK and JC were quantitated in urine. Detectable virus was analyzed with respect to secondary fungal and opportunistic bacterial infections, ICU duration, severity of illness, and survival. Patients with protracted sepsis had markedly increased frequency of detectable virus. Cumulative viral DNA detection rates in blood were: CMV (24.2%), EBV (53.2%), HSV (14.1%), HHV-6 (10.4%), and TTV (77.5%). 42.7% of septic patients had presence of two or more viruses. The 50% detection rate for herpesviruses was 5-8 days after sepsis onset. A small subgroup of septic patients had markedly elevated viral loads (>104-106 DNA copies/ml blood) for CMV, EBV, and HSV. Excluding TTV, DNAemia was uncommon in critically-ill non-septic patients and in age-matched healthy controls. Compared to septic patients without DNAemia, septic patients with viremia had increased fungal and opportunistic bacterial infections. Patients with detectable CMV in plasma had higher 90-day mortality compared to CMV-negative patients; p<0.05. Reactivation of latent viruses is common with prolonged sepsis, with frequencies similar to those occurring in transplant patients on immunosuppressive therapy and consistent with development of an immunosuppressive state. Whether reactivated latent viruses contribute to morbidity and mortality in sepsis remains unknown.

L-plastin is essential for alveolar macrophage production and control of pulmonary pneumococcal infection.

We report that mice deficient for the hematopoietic-specific, actin-bundling protein L-plastin (LPL) succumb rapidly to intratracheal pneumococcal infection. The increased susceptibility of LPL(-/-) mice to pulmonary pneumococcal challenge correlated with reduced numbers of alveolar macrophages, consistent with a critical role for this cell type in the immediate response to pneumococcal infection. LPL(-/-) mice demonstrated a very early clearance defect, with an almost 10-fold-higher bacterial burden in the bronchoalveolar lavage fluid 3 h following infection. Clearance of pneumococci from the alveolar space in LPL(-/-) mice was defective compared to that in Rag1(-/-) mice, which lack all B and T lymphocytes, indicating that innate immunity is defective in LPL(-/-) mice. We did not identify defects in neutrophil or monocyte recruitment or in the production of inflammatory cytokines or chemokines that would explain the early clearance defect. However, efficient alveolar macrophage regeneration following irradiation required LPL. We thus identify LPL as being key to alveolar macrophage development and essential to an effective antipneumococcal response. Further analysis of LPL(-/-) mice will illuminate critical regulators of the generation of alveolar macrophages and, thus, effective pulmonary innate immunity.

TLR3 agonist improves survival to secondary pneumonia in a double injury model.

BACKGROUND: Toll-like receptors (TLR) can initiate various immune responses and are therefore activated under diverse infectious states. Previous studies have focused on TLR3 primarily as an antiviral pathway. However, recent research has demonstrated its efficacy in bacterial infection. Having developed a murine double injury model of cecal ligation and puncture (CLP) followed by Pseudomonas aeruginosa (Pa), we hypothesized that targeted administration of Poly I:C, a TLR3 agonist, would protect mice against secondary pneumonia. MATERIAL AND METHODS: B6 mice underwent CLP followed 4 d afterward by an intranasal dose of Pa. Animals were given Poly I:C or vehicle (phosphate-buffered saline) intranasally 24 h post CLP and every day thereafter for a total of 6 d. For acute studies, mice were sacrificed at two time points, 4 d post CLP and 1 d post pneumonia (Pa). RESULTS: Poly I:C treatment led to a significant improvement in survival (69% versus 33%). Cytokine analysis from bronchioalveolar lavage displayed significant differences both immediately before and after pneumonia. Bronchioalveolar lavage cultures taken at 24 h post double injury showed significantly higher colony counts in the lungs of control animals compared with those of Poly I:C animals. Measurements of TLR3 expression showed significant increases within both the immune and lung epithelial cells of Poly I:C-treated mice. Finally, the lungs of treated animals had significant increases in lymphocytes and innate cells. CONCLUSIONS: The prophylactic treatment applied in this clinically relevant model further illustrates the overarching hypothesis of immune dysfunction and the possibility of corrective immune modulation within the setting of sepsis.

Nitric oxide delivery during cardiopulmonary bypass reduces postoperative morbidity in children--a randomized trial.

OBJECTIVE: Cardiac surgery requiring cardiopulmonary bypass and cardioplegic arrest leads to myocardial ischemic and reperfusion injury. Gaseous nitric oxide has been demonstrated to have a myocardial protective effect following ischemia-reperfusion. We hypothesized that gaseous nitric oxide administered during cardiopulmonary bypass would have similar beneficial effects. METHODS: In a prospective, randomized, blinded, placebo-controlled study, children undergoing repair of tetralogy of Fallot received either 20 ppm of gaseous nitric oxide or placebo delivered to the membrane oxygenator during cardiopulmonary bypass. RESULTS: A total of 16 children were randomized into 2 equal groups once their parents or guardians had given written informed consent. No differences were found in age, crossclamp time, cardiopulmonary bypass time, or methemoglobin between the 2 groups. The group receiving gaseous nitric oxide had a significantly shortened duration of mechanical ventilation (8.4 ± 7.6 vs 16.3 ± 6.5 hours; P < .05) and intensive care unit length of stay (53.8 ± 19.7 vs 79.4 ± 37.7 hours; P < .05) compared with the placebo group. The patients had significantly lower troponin levels at 12, 24, and 48 hours (P < .05) and lower B-type natriuretic peptide levels at 12 and 24 hours (P < .05). A trend was found toward a less positive fluid balance, with significantly less diuretic usage. The study patients had a greater mean hemoglobin at 48 hours, despite the absence of differences in chest tube output, packed red blood cell transfusion, platelet counts or transfusion requirements, fresh frozen plasma transfusion, or prothrombin time/partial thromboplastin time in the first 48 hours. CONCLUSIONS: The delivery of gaseous nitric oxide to the cardiopulmonary bypass circuit for children undergoing cardiac surgery results in myocardial protection, improved fluid balance, and an improved postoperative intensive care unit course.

Detection of viruses in young children with fever without an apparent source.

OBJECTIVE: Fever without an apparent source is common in young children. Currently in the United States, serious bacterial infection is unusual. Our objective was to determine specific viruses that might be responsible. METHODS: We enrolled children aged 2 to 36 months with temperature of 38°C or greater without an apparent source or with definite or probable bacterial infection being evaluated in the St Louis Children's Hospital Emergency Department and afebrile children having ambulatory surgery. Blood and nasopharyngeal swab samples were tested with an extensive battery of virus-specific polymerase chain reaction assays. RESULTS: One or more viruses were detected in 76% of 75 children with fever without an apparent source, 40% of 15 children with fever and a definite or probable bacterial infection, and 35% of 116 afebrile children (P < .001). Four viruses (adenovirus, human herpesvirus 6, enterovirus, and parechovirus) were predominant, being detected in 57% of children with fever without a source, 13% of children with fever and definite or probable bacterial infection, and 7% of afebrile children (P < .001). Thirty-four percent of 146 viral infections were detected only by polymerase chain reaction performed on blood. Fifty-one percent of children with viral infections and no evidence of bacterial infection were treated with antibiotics. CONCLUSIONS: Viral infections are frequent in children with fever without an apparent source. Testing of blood in addition to nasopharyngeal secretions expanded the range of viruses detected. Future studies should explore the utility of testing for the implicated viruses. Better recognition of viruses that cause undifferentiated fever in young children may help limit unnecessary antibiotic use.

Preliminary evidence for leukocyte transcriptional signatures for pediatric ventilator-associated pneumonia.

OBJECTIVE: Ventilator-associated pneumonia (VAP) is a significant contributor to intensive care unit (ICU) morbidity and mortality and presents a significant diagnostic challenge. Our hypothesis was that blood RNA expression profiles can be used to track the response to VAP in children, using the same methods that proved informational in adults. DESIGN: A pilot, nonrandomized, repeated measures case-control study of changes in the abundance of total RNA in buffy coat and clinical scores for VAP. SETTING: A large, multispecialty university-based pediatric ICU and cardiac ICU. PATIENTS: Seven children requiring intubation and mechanical ventilation. INTERVENTIONS: Blood samples were drawn at time of enrollment and every 48 hours for a maximum of 11 samples (21 days). Patients ranged in age from 1 to 18 months (mean 8 months). All patients survived to the end of the study. Of the 7 patients studied, 4 developed VAP. MEASUREMENTS AND MAIN RESULTS: Statistical analysis of the Affymetrix Human Genome Focus GeneChip signal was conducted on normalized expression values of 8793 probe sets using analysis of variance (ANOVA) with a false discovery rate of 0.10. The expression patterns of 48 genes appeared to discriminate between the 2 classes of ventilated children: those with and those without pneumonia. Gene expression network analysis revealed several gene ontologies of interest, including cell proliferation, differentiation, growth, and apoptosis, as well as genes not previously implicated in sepsis. CONCLUSIONS: These preliminary data are the first in critically ill children supporting the hypothesis that there is a detectable VAP signal in gene expression profiles. Larger studies are needed to validate these preliminary findings and test the diagnostic value of longitudinal changes in leukocyte RNA signatures.

Evaluation of the precision of emergency department diagnoses in young children with fever.

OBJECTIVE. To characterize causes of fever in children presenting to a pediatric emergency department (ED). METHODS. One-year retrospective review of ED records. Inclusion criteria were 2 to 36 months of age with a documented temperature ≥ 39°C. Exclusion criteria were elopement, repeat visit, and underlying diagnosis with a predisposition to infection. Medical records were reviewed using a predefined, study-specific, data abstraction tool. Based on diagnosis and pathogen detection, visits were assigned to 3 groups, laboratory confirmed pathogen and focal or nonfocal diagnosis without confirmed pathogen. RESULTS. A total of 1091 visits met inclusion criteria. Fourteen percent had a pathogen detected, 56% had a focal diagnosis without a confirmed pathogen, and 30% had a nonfocal diagnosis without confirmed pathogen. CONCLUSIONS. In a cohort of febrile children 2 to 36 months of age, only 14% had a confirmed pathogen. New rapid viral diagnostic techniques may provide an opportunity to improve diagnostic certainty in young children presenting with fever.

Increased susceptibility to Candida infection following cecal ligation and puncture.

Secondary infection following septic insult represents a significant cause of morbidity and mortality in hospitalized patients. Sepsis induced immunosuppression is a major factor in the host's susceptibility to nosocomial infections and Candida albicans accounts for a growing number of these. Given the importance of improving our understanding of the immune response to sepsis and the increasing rates of C. albicans infections, we sought to develop a murine model of double injury consisting of primary peritonitis, i.e., cecal ligation and puncture (CLP), followed by a secondary challenge of C. albicans. As observed in previous work, after primary injury the immune profile of the host changes over time. Therefore, while keeping the mortality rates from the respective individual injuries low, we altered the timing of the secondary injury between two post-CLP time points, day two and day four. Mice subjected to C. albicans infection following CLP have significantly different survival rates dependent upon timing of secondary injury. Animals challenged with C. albicans at two days post CLP had 91% mortality whereas animals challenged at four days had 47% mortality. This improvement in survival at four days was associated with restoration of innate cell populations and as evidenced by stimulated splenocytes, increases in certain inflammatory cytokines. In addition, we show that susceptibility to C. albicans infection following CLP is dependent upon the depth of immunosuppression. Although at four days post-CLP there is a partial reconstitution of the immune system, these animals remain more susceptible to infection compared to their single injury (C. albicans alone) counterparts. Collectively, these studies demonstrate that immunosuppression following initial septic insult changes over time. This novel, two hit model of CLP followed by Candida provides additional insight into the immune compromised state created by primary peritonitis, and thereby opens up another avenue of investigation into the causes and possible cures of an emerging clinical problem.

Evidence for a novel blood RNA diagnostic for pediatric appendicitis: the riboleukogram.

OBJECTIVE: To test the hypothesis that gene expression analysis of circulating white blood cells and/or plasma cytokines could be used to improve diagnostic accuracy in children being evaluated for appendicitis. METHODS: We recruited 28 children being evaluated for abdominal pain from a tertiary pediatric emergency department. Twenty patients were used as a training cohort and 8 patients as a validation cohort. After consent was obtained, blood was processed for plasma cytokine analysis and RNA gene expression. Alvarado and pediatric appendicitis scores were obtained. Principal components analysis was used to explore global differences in gene expression. The random forest method was used to classify patients into those with and without appendicitis in the prospective cohort. Comparisons were made evaluating clinical scoring systems, cytokine analysis, and gene expression analysis to accurately predict appendicitis. RESULTS: The random forest method accurately predicted appendicitis in 4 of 5 patients in the prospective cohort. Cytokine analysis was not as accurate as gene expression analysis; however, it did accurately rule out all 3 patients in the prospective cohort. Pediatric appendicitis scores and Alvarado scores were not useful for predicting appendicitis. CONCLUSIONS: Our findings provide proof of technical feasibility and support the diagnostic potential of plasma cytokines to rule out and riboleukograms to rule in the diagnosis of appendicitis.

IL-7 promotes T cell viability, trafficking, and functionality and improves survival in sepsis.

Sepsis is a highly lethal disorder characterized by widespread apoptosis-induced depletion of immune cells and the development of a profound immunosuppressive state. IL-7 is a potent antiapoptotic cytokine that enhances immune effector cell function and is essential for lymphocyte survival. In this study, recombinant human IL-7 (rhIL-7) efficacy and potential mechanisms of action were tested in a murine peritonitis model. Studies at two independent laboratories showed that rhIL-7 markedly improved host survival, blocked apoptosis of CD4 and CD8 T cells, restored IFN-gamma production, and improved immune effector cell recruitment to the infected site. Importantly, rhIL-7 also prevented a hallmark of sepsis (i.e., the loss of delayed-type hypersensitivity), which is an IFN-gamma- and T cell-dependent response. Mechanistically, rhIL-7 significantly increased the expression of the leukocyte adhesion markers LFA-1 and VLA-4, consistent with its ability to improve leukocyte function and trafficking to the infectious focus. rhIL-7 also increased the expression of CD8. The potent antiapoptotic effect of rhIL-7 was due to increased Bcl-2, as well as to a dramatic decrease in sepsis-induced PUMA, a heretofore unreported effect of IL-7. If additional animal studies support its efficacy in sepsis and if current clinical trials continue to confirm its safety in diverse settings, rhIL-7 should be strongly considered for clinical trials in sepsis.

Neutrophils are significant producers of IL-10 during sepsis.

Sepsis is a syndrome involving systemic inflammation as well as an infectious focus. Accordingly, the host immune response to sepsis involves complex leukocyte interplay that is incompletely understood. It is known that the immunoregulatory cytokine, IL-10, is rapidly expressed during the early stages of sepsis. In a murine model of sepsis, we sought to elucidate which leukocytes are early IL-10 producers. Using a novel IL-10 transcriptional reporter mouse, we observed that splenic leukocytes produced little IL-10. At the site of infection, peritoneal neutrophils produced the highest levels of IL-10 among leukocytes. Using cytokine antibody labeling, we further show that peritoneal neutrophils had high amounts of intracellular IL-10. We next depleted neutrophils and found a 40% decrease in peritoneal IL-10 levels. Altogether, this report demonstrates that among leukocytes, neutrophils are significant contributors of IL-10 at the site of infection during sepsis.