Procalcitonin, C-reactive protein, neutrophil gelatinase-associated lipocalin, resistin and the APTT waveform for the early diagnosis of serious bacterial infection and prediction of outcome in critically ill children.

OBJECTIVE: Bacterial Infections remains a leading cause of death in the Paediatric Intensive Care Unit (PICU). In this era of rising antimicrobial resistance, new tools are needed to guide antimicrobial use. The aim of this study was to investigate the accuracy of procalcitonin (PCT), neutrophil gelatinase-associated lipocalin (NGAL), resistin, activated partial thromboplastin time (aPTT) waveform and C-reactive protein (CRP) for the diagnosis of serious bacterial infection (SBI) in children on admission to PICU and their use as prognostic indicators. SETTING: A regional PICU in the United Kingdom. PATIENTS: Consecutive PICU admissions between October 2010 and June 2012. MEASUREMENTS: Blood samples were collected daily for biomarker measurement. The primary outcome measure was performance of study biomarkers for diagnosis of SBI on admission to PICU based on clinical, radiological and microbiological criteria. Secondary outcomes included durations of PICU stay and invasive ventilation and 28-day mortality. Patients were followed up to day 28 post-admission. MAIN RESULTS: A total of 657 patients were included in the study. 92 patients (14%) fulfilled criteria for SBI. 28-day mortality was 2.6% (17/657), but 8.7% (8/92) for patients with SBI. The combination of PCT, resistin, plasma NGAL and CRP resulted in the greatest net reclassification improvement compared to CRP alone (0.69, p<0.005) with 10.5% reduction in correct classification of patients with SBI (p 0.52) but a 78% improvement in correct classification of patients without events (p <0.005). A statistical model of prolonged duration of PICU stay found log-transformed maximum values of biomarkers performed better than first recorded biomarkers. The final model included maximum values of CRP, plasma NGAL, lymphocyte and platelet count (AUC 79%, 95% CI 73.7% to 84.2%). Longitudinal profiles of biomarkers showed PCT levels to decrease most rapidly following admission SBI. CONCLUSION: Combinations of biomarkers, including PCT, may improve accurate and timely identification of SBI on admission to PICU.

Title NMR-based metabolic profiling provides diagnostic and prognostic information in critically ill children with suspected infection.

Sepsis, defined as life-threatening organ dysfunction caused by infection is difficult to distinguish clinically from infection or post-operative inflammation. We hypothesized that in a heterogeneous group of critically ill children, there would be different metabolic profiles between post-operative inflammation, bacterial and viral infection and infection with or without organ dysfunction. 1D 1H nuclear magnetic resonance spectra were acquired in plasma samples from critically ill children. We included children with bacterial (n = 25) and viral infection (n = 30) and controls (n = 58) (elective cardiac surgery without infection). Principal component analysis was used for data exploration and partial least squares discriminant analysis models for the differences between groups. Area under receiver operating characteristic curve (AUC) values were used to evaluate the models. Univariate analysis demonstrated differences between controls and bacterial and viral infection. There was excellent discrimination between bacterial and control (AUC = 0.94), and viral and control (AUC = 0.83), with slightly more modest discrimination between bacterial and viral (AUC = 0.78). There was modest discrimination (AUC = 0.73) between sepsis with organ dysfunction and infection with no organ dysfunction. In critically ill children, NMR metabolomics differentiates well between those with a post-operative inflammation but no infection, and those with infection (bacterial and viral), and between sepsis and infection.

Identifying critically ill children at high risk of acute kidney injury and renal replacement therapy.

Acute kidney injury (AKI), a common complication in paediatric intensive care units (PICU), is associated with increased morbidity and mortality. In this single centre, prospective, observational cohort study, neutrophil gelatinase-associated lipocalin in urine (uNGAL) and plasma (pNGAL) and renal angina index (RAI), and combinations of these markers, were assessed for their ability to predict severe (stage 2 or 3) AKI in children and young people admitted to PICU. In PICU children and young people had initial and serial uNGAL and pNGAL measurements, RAI calculation on day 1, and collection of clinical data, including serum creatinine measurements. Primary outcomes were severe AKI and renal replacement therapy (RRT). Secondary outcomes were length of stay, hospital acquired infection and mortality. The area under the Receiver Operating Characteristic (ROC) curves and Youden index was used to determine biomarker performance and identify optimum cut-off values. Of 657 children recruited, 104 met criteria for severe AKI (15∙8%) and 47 (7∙2%) required RRT. Severe AKI was associated with increased length of stay, hospital acquired infection, and mortality. The area under the curve (AUC) for severe AKI prediction for Day 1 uNGAL, Day 1 pNGAL and RAI were 0.75 (95% Confidence Interval [CI] 0∙69, 0∙81), 0∙64 (95% CI 0∙56, 0∙72), and 0.73 (95% CI 0∙65, 0∙80) respectively. The optimal combination of measures was RAI and day 1 uNGAL, giving an AUC of 0∙80 for severe AKI prediction (95% CI 0∙71, 0∙88). In this heterogenous PICU cohort, urine or plasma NGAL in isolation had poorer prediction accuracy for severe AKI than in previously reported homogeneous populations. However, when combined together with RAI, they produced good prediction for severe AKI.

Staphylococcus aureus with reduced glycopeptide susceptibility in Liverpool, UK.

OBJECTIVES: To investigate if colonization with heterogeneous glycopeptide-intermediate Staphylococcus aureus (hGISA) is associated with hGISA bacteraemia. METHODS: Isolates of methicillin-resistant S. aureus (MRSA) from blood cultures and from swabs to detect MRSA colonization were screened for reduced susceptibility to glycopeptides by an agar incorporation method. Isolates detected by this screen were tested for glycopeptide resistance by MacroEtest, standard MIC Etest methods and population analysis profile-AUC (PAP-AUC) analysis. S. aureus isolates with and without reduced glycopeptide susceptibility were characterized by PFGE and spa typing. RESULTS: MRSA isolates with reduced susceptibility to glycopeptides, as identified by the MacroEtest method, were detected in the colonization screens of 86 of 2550 MRSA-positive patients. The isolates were confirmed by Etest MIC and PAP-AUC analysis as hGISA. A total of 82/86 of the hGISA colonizing isolates were EMRSA-16 by PFGE; the remainder were EMRSA-15. Bacteraemia with hGISA was identified in five patients during the study period; two isolates were EMRSA-16 and three were EMRSA-15. hGISA colonization could not be linked to hGISA bacteraemia and hGISA bacteraemia could not be linked to hGISA colonization. Four of the five hGISA bacteraemias developed following teicoplanin therapy for a central venous catheter-associated MRSA bacteraemia. CONCLUSIONS: Laboratory strategies to reduce morbidity associated with hGISA should focus on testing for hGISA in bacteraemic (rather than colonizing) MRSA isolates in patients with recurrent S. aureus bacteraemia following glycopeptide exposure.

CpG oligodeoxynucleotide 5mer-induced apoptosis in MOLT-4 leukaemia cells does not require caspase 3 or new protein synthesis.

We have established that CpG oligodeoxynucleotide 5mers, of sequence type CGNNN (N = A, G, C or T), rapidly induce apoptosis/cell cycle arrest in human leukaemia lines. The 5'-CpG is obligatory for these effects. Induction of apoptosis in MOLT-4 cells did not require new protein synthesis and was insensitive to the caspase 3 inhibitor, Ac-DEVD-CHO, although the latter abrogated DNA laddering, phosphatidylserine externalization and collapse of the mitochondrial transmembrane potential. A subline of MOLT-4 cells, MOLT-4CpGR, was selected for acquired resistance to CpG 5mers. Differences in gene expression between MOLT-4 and MOLT-4CpGR cells were identified following three independent reciprocal cDNA subtractions, consensus selection and virtual cloning through targeted display. Several known genes were implicated in the action of or resistance to CpG oligodeoxynucleotide 5mers. Their protein products listed below immediately suggest cell signalling pathways/processes worthy of further investigation in elucidating the mechanism of CpG 5mer activity: caspase 2, the transcription factors Atf4, Hic, HoxB3 and Rqcd1, the splicing factors Rbmx, Sfrs5 and Sfrs7, the DNA replication factors Mcm5 and Brd4, phosphoinositide-3-kinase, annexin A1, mucosa-associated lymphoid tissue lymphoma translocation 1 and three enzymes involved in protein ubiquitylation, Siah1, Gsa7 and Nin283.