Early Inflammatory Markers for the Diagnosis of Late-Onset Sepsis in Neonates: The Nosodiag Study.

Background: Early diagnosis is essential to improve the treatment and prognosis of newborn infants with nosocomial bacterial infections. Although cytokines and procalcitonin (PCT) have been evaluated as early inflammatory markers, their diagnostic properties have rarely been compared. Objectives: This study evaluated and compared the ability of individual inflammatory markers available for clinician (PCT, semi-quantitative determination of IL-8) and of combinations of markers (CRPi plus IL-6 or quantitative or semi-quantitative determination of IL-8) to diagnose bacterial nosocomial infections in neonates. Methods: This prospective two-center study included neonates suspected of nosocomial infections from September 2008 to January 2012. Inflammatory markers were measured initially upon suspicion of nosocomial infection, and CRP was again measured 12-24 h later. Newborns were retrospectively classified into two groups: those who were infected (certainly or probably) and uninfected (certainly or probably). Results: The study included 130 infants of median gestational age 28 weeks (range, 24-41 weeks). Of these, 34 were classified as infected and 96 as uninfected. The sensitivity, specificity, positive and negative predictive values (PPV and NPV), and positive and negative likelihood ratios (LR+ and LR-) for PCT were 59.3% (95% confidence interval [CI], 38.8-77.6%), 78.5% (95% CI, 67.8-86.9%), 48.5% (95% CI, 30.8-66.5%), 84.9% (95% CI, 74.6-92.2%), 2.7 (95% CI, 1.6-4.9), and 0.5 (95% CI, 0.3-0.8), respectively. Semi-quantitative IL-8 had the highest specificity (92.19%; 95% CI, 82.70-97.41%), PPV (72.22%; 95% CI, 46.52-90.30%) and LR+ (6.17, 95% CI, 2.67-28.44), but had low specificity (48.15%; 95% CI, 28.67-68.05%). Of all markers tested, the combination of IL-6 and CRPi had the highest sensitivity (78.12%; 95% CI, 60.03-90.72%), NPV (91.3%; 95% CI, 82.38-96.32%) and LR- (0.29; 95% CI, 0.12-0.49). The combination of IL-6 and CRPi had a higher area under the curve than PCT, but with borderline significance (p = 0.055). Conclusions: The combination of IL-6 and CRPi was superior to other methods, including PCT, for the early diagnosis of nosocomial infection in neonates, but was not sufficient for sole use. The semi-quantitative determination of IL-8 had good diagnostic properties but its sensitivity was too low for use in clinical practice.

Extensive study of human insulin immunoassays: promises and pitfalls for insulin analogue detection and quantification.

BACKGROUND: Over the last few decades, new synthetic insulin analogues have been developed. Their measurement is of prime importance in the investigation of hypoglycaemia, but their quantification is hampered by variable cross-reactivity with many insulin assays. For clinical analysis, it has now become essential to know the potential cross-reactivity of analogues of interest. METHODS: In this work, we performed an extensive study of insulin analogue cross-reactivity using numerous human insulin immunoassays. We investigated the cross-reactivity of five analogues (lispro, aspart, glulisine, glargine, detemir) and two glargine metabolites (M1 and M2) with 16 commercial human insulin immunoassays as a function of concentration. RESULTS: The cross-reactivity values for insulin analogues or glargine metabolites ranged from 0% to 264%. Four assays were more specific to human insulin, resulting in negligible cross-reactivity with the analogues. However, none of the 16 assays was completely free of cross-reactivity with analogues or metabolites. The results show that analogue cross-reactivity, which varies to a large degree, is far from negligible, and should not be overlooked in clinical investigations. CONCLUSIONS: This study has established the cross-reactivity of five insulin analogues and two glargine metabolites using 16 immunoassays to facilitate the choice of the immunoassay(s) and to provide sensitive and specific analyses in clinical routine or investigation.

The impact of dialysis solution biocompatibility on ultrafiltration and on free water transport in rats.

This study compares different peritoneal dialysis fluids (PDF) in rats over a short contact time. For greater accuracy, net ultrafiltration (UF) and peritoneal transport indices, mass transfer area coefficient (MTAC) were scaled for the in vivo peritoneal surface area recruited (ivPSA) measured by microcomputerized tomography. Wistar rats underwent nephrectomy (5/6ths), were randomized into two groups and given 1.5% glucose PDF, either conventional acidic lactate (n = 14) or pH neutral bicarbonate (BicaVera) (n = 13); MTAC and UF were measured using a 90-min peritoneal equilibrium test (PET), fill volume (IPV) of 10 ml/100 g; small pore fluid transport was determined from sodium balance and used to calculate free water transport (FWT). Each ivPSA value was significantly correlated with the actual IPV, which varied from one rat to another. At 90 min of contact, there was no difference in recruited ivPSA in relation to PDFs. There was a difference (p < 0.01) in net UF/ivPSA 0.45 vs. 1.41 cm(2)/ml for bicarbonate versus lactate, as there was in the proportion of FWT with bicarbonate (42 ± 5% of net UF) compared to lactate (29 ± 4% of net UF). Net UF for individual values of ivPSA differs between conventional PDF and more biocompatible solutions, such as bicarbonate PDF. This observed change in UF cannot be fully explained by differences in glucose transport. The changes in FWT may be explained by the impact of the PDF biocompatibility on aquaporin function.

Transient Bcl-2 gene down-expression in circulating mononuclear cells of severe sepsis patients who died despite appropriate intensive care.

OBJECTIVE: To assess the levels of expression of the antiapoptotic gene Bcl-2 and the proapoptotic gene Bax in circulating mononuclear cells (CMNC) harvested during the course of severe sepsis (SS) in formerly non-immunocompromised patients undergoing hospital-acquired infection, in parallel to cytokine levels. DESIGN: Prospective study. SETTING: Intensive care unit. PARTICIPANTS: A total of 24 patients without immunodeficiency undergoing standard goal-directed therapy for nosocomial SS, 10 critically ill patients without sepsis, and 10 healthy controls. INTERVENTIONS: Blood was collected before infection and within 12 h, 1, 3 and 7 days after fever onset, to determine plasma concentrations of IL-6, IL-10, TNF-alpha, C-reactive protein, whole blood cell counts, lymphocyte subsets, annexin V labelling for apoptosis, and Bax and Bcl-2 relative RNA expression by real-time polymerase chain reaction. RESULTS: SS patients displayed increased cytokine concentrations, TNF-alpha being significantly increased at full-blown sepsis. Within 12 h after onset of infection, lymphocyte counts were lower in SS patients than in critically ill controls ( p=0.001), and this phenomenon was marked in CD4+ and CD8+ subsets ( p<0.001). This was associated with enhanced apoptosis in CMNC (15.7+/-8.7% vs 3.4+/-2.1%, p<0.001) and a significant down-expression of the Bcl-2 gene throughout the study ( p<0.05). In contrast, the expression of Bax did not change significantly. Within 12 h of fever onset, non-survivors expressed a 10-fold down-expression of Bcl-2 when compared to survivors ( p<0.001). CONCLUSIONS: An early transient down-expression of the gene Bcl-2 occurred in CMNC harvested from SS patients who died despite intensive care. In contrast, the expression of the gene Bax did not change significantly.