Risk of Early-Onset Neonatal Infection with Maternal Infection or Colonization: A Global Systematic Review and Meta-Analysis

Background

Neonatal infections cause a significant proportion of deaths in the first week of life, yet little is known about risk factors and pathways of transmission for early-onset neonatal sepsis globally. We aimed to estimate the risk of neonatal infection (excluding sexually transmitted diseases [STDs] or congenital infections) in the first seven days of life among newborns of mothers with bacterial infection or colonization during the intrapartum period.

Methods and Findings

We searched PubMed, Embase, Scopus, Web of Science, Cochrane Library, and the World Health Organization Regional Databases for studies of maternal infection, vertical transmission, and neonatal infection published from January 1, 1960 to March 30, 2013. Studies were included that reported effect measures on the risk of neonatal infection among newborns exposed to maternal infection. Random effects meta-analyses were used to pool data and calculate the odds ratio estimates of risk of infection. Eighty-three studies met the inclusion criteria. Seven studies (8.4%) were from high neonatal mortality settings. Considerable heterogeneity existed between studies given the various definitions of laboratory-confirmed and clinical signs of infection, as well as for colonization and risk factors. The odds ratio for neonatal lab-confirmed infection among newborns of mothers with lab-confirmed infection was 6.6 (95% CI 3.9–11.2). Newborns of mothers with colonization had a 9.4 (95% CI 3.1–28.5) times higher odds of lab-confirmed infection than newborns of non-colonized mothers. Newborns of mothers with risk factors for infection (defined as prelabour rupture of membranes [PROM], preterm <37 weeks PROM, and prolonged ROM) had a 2.3 (95% CI 1.0–5.4) times higher odds of infection than newborns of mothers without risk factors.

Conclusions

Neonatal infection in the first week of life is associated with maternal infection and colonization. High-quality studies, particularly from settings with high neonatal mortality, are needed to determine whether targeting treatment of maternal infections or colonization, and/or prophylactic antibiotic treatment of newborns of high risk mothers, may prevent a significant proportion of early-onset neonatal sepsis. Please see later in the article for the Editors'' Summary     

Regional susceptibility to TNF-α induction of murine brain inflammation via classical IKK/NF-κB signalling

It is becoming clear that inflammation plays a significant role in a number of neurological and psychiatric conditions. Post mortem brain samples in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, schizophrenia and most recently autism spectrum condition, all exhibit neuroglial activation and inflammatory markers within the CSF. Many questions remain about the underlying molecular mechanisms. By adding the pro-inflammatory cytokine, TNF-α, to mouse brain tissue we demonstrated that the frontal lobes and temporal region, areas involved in higher functions such as memory and learning, are most susceptible to cytokine-induced inflammation via the NF-κB signalling pathway. We observed direct correlations between the volumetric increase and molecular expression indicating that therapeutic targets in these lobes may require different approaches when treating conditions with a central neuroinflammatory component.     

Examination of sex attractants for monitoring weed biological control agents in Hawaii

The identification of sex attractants was undertaken for potential use in the study of two biological control agents against Rubus spp. in Hawaii. Attractants for Croesia zimmermani (Lepidoptera: Tortricidae) and Schreckensteinia festaliella (Lepidoptera: Heliodinidae) were developed by field screening a variety of putative lures in sticky traps, based on attractants for congeneric species. Croesia zimmermani was most attracted to E11-tetradecen-1-ol and E11-tetradecenal, while S. festaliella was attracted to (10,12)-(E,E)-hexadecadienal alone. Development of monitoring systems based on sex attractants can enable better evaluation of biocontrol programmes, and provide cost-effective information on presence/absence, density, phenology, synchrony with the host, dispersal rate and other useful parameters.     

Floral scent of Canada thistle and its potential as a generic insect attractant

The flowers of Canada thistle, Cirsium arvense (L.), attract a wide range of insects, including pollinators and herbivorous species. This attraction is primarily mediated by floral odor, which offers potential for developing generic insect attractants based on odor. In this study, we have analyzed the chemical composition of the volatiles produced by Canada thistle flowers. Nineteen floral compounds were identified in the headspace, including phenylacetaldehyde (55%), methyl salicylate (14%), dimethyl salicylate (8%), pyranoid linalool oxide (4.5%), and benzaldehyde (3.5%). Other minor compounds include benzyl alcohol, methylbenzoate, linalool, phenylethyl alcohol, furanoid linalool oxide, p-anisaldehyde, 2,6-dimethyl-1,3,5,7-octatetraene, benzylacetate, benzyl tiglate, (E,E)-alpha-farnesene, benzyl benzoate, isopropyl myristate, and 2-phenylethyl ester benzoic acid. The relative attractiveness of various doses of the main floral volatile compound phenylacetaldehyde (i.e., 10, 100, 200, and 400 mg) was tested for insect attraction. Both the total catch and the biodiversity of insect species trapped increased as the loading of phenylacetaldehyde increased. Volatiles were chosen from the odors from the flowers of Canada thistle and formulated and tested in the field. An 11-component blend was the most attractive of several floral blends tested. These findings indicate that chemical components of flower odors of Canada thistle can serve as a generic insect attractant for monitoring of invasive pest species.     

Plant and host effects on the leafroller parasitoid Dolichogenidia tasmanica

Parasitism by the braconid wasp Dolichogenidia tasmanica of first instar larvae of the lightbrown apple moth Epiphyas postvittana, established on four different species of potted host plants, was assessed after 2 weeks of field exposure in an apple orchard. Parasitism varied significantly between larval host plants (apple 58%, broom 59%, clover 30%, poplar 19% ). Parasitism on potted apple seedlings of the co-evolutionary host, E. postvittana, was compared in a field trial with that of two native New Zealand leafroller species (to which D. tasmanica has had exposure for 5 decades only). Parasitism varied significantly with larval host (E. postvittana, 83%; Ctenopseustis herana, 58%;Planotortrix octo, 26% ). Larval collections were made from mature apple trees and identification of larvae was achieved by DNA analysis for the leafroller species using PCR-RFLP of ITS1 + ITS2, and for the parasitoid by specific PCR of partial 18S. Parasitism under natural field conditions on mature apple trees was not different between larval hosts (mean 32.5% ). In laboratory studies, more P. octo larvae departed in response to parasitoid probing behaviour than E. postvittana, which is likely to contribute to the difference in parasitism rates. This study conclusively shows that D. tasmanica parasitises native New Zealand leafrollers, despite their different evolutionary origins.     

Dispersed activation in the left temporal cortex for speech-reading in congenitally deaf people

Does the lateral temporal cortex require acoustic exposure in order to become specialized for speech processing? Six hearing participants and six congenitally deaf participants, all with spoken English as their first langugage, were scanned using functional magnetic resonance imaging while performing a simple speech-reading task. Focal activation of the left lateral temporal cortex was significantly reduced in the deaf group compared with the hearing group. Activation within this region was present in individual deaf participants, but varied in location from person to person. Early acoustic experience may be required for regions within the left temporal cortex in order to develop into a coherent network with subareas devoted to specific speech analysis functions.     

Effects of Steroid Hormones on Sex Differences in Cerebral Perfusion

Sex differences in the brain appear to play an important role in the prevalence and progression of various neuropsychiatric disorders, but to date little is known about the cerebral mechanisms underlying these differences. One widely reported finding is that women demonstrate higher cerebral perfusion than men, but the underlying cause of this difference in perfusion is not known. This study investigated the putative role of steroid hormones such as oestradiol, testosterone, and dehydroepiandrosterone sulphate (DHEAS) as underlying factors influencing cerebral perfusion. We acquired arterial spin labelling perfusion images of 36 healthy adult subjects (16 men, 20 women). Analyses on average whole brain perfusion levels included a multiple regression analysis to test for the relative impact of each hormone on the global perfusion. Additionally, voxel-based analyses were performed to investigate the sex difference in regional perfusion as well as the correlations between local perfusion and serum oestradiol, testosterone, and DHEAS concentrations. Our results replicated the known sex difference in perfusion, with women showing significantly higher global and regional perfusion. For the global perfusion, DHEAS was the only significant predictor amongst the steroid hormones, showing a strong negative correlation with cerebral perfusion. The voxel-based analyses revealed modest sex-dependent correlations between local perfusion and testosterone, in addition to a strong modulatory effect of DHEAS in cortical, subcortical, and cerebellar regions. We conclude that DHEAS in particular may play an important role as an underlying factor driving the difference in cerebral perfusion between men and women.     

Bias and Sampling Error of the Estimated Proportion of Genotypic Variance Explained by Quantitative Trait Loci Determined From Experimental Data in Maize Using Cross Validation and Validation With Independent Samples.

Cross validation (CV) was used to analyze the effects of different environments and different genotypic samples on estimates of the proportion of genotypic variance explained by QTL (p). Testcrosses of 344 F(3) maize lines grown in four environments were evaluated for a number of agronomic traits. In each of 200 replicated CV runs, this data set was subdivided into an estimation set (ES) and various test sets (TS). ES were used to map QTL and estimate p for each run (p(ES)) and its median (p(ES)) across all runs. The bias of these estimates was assessed by comparison with the median (p(TS.ES)) obtained from TS. We also used two independent validation samples derived from the same cross for further comparison. The median p(ES) showed a large upward bias compared to p(TS.ES). Environmental sampling generally had a smaller effect on the bias of p(ES) than genotypic sampling or both factors simultaneously. In independent validation, p(TS.ES) was on average only 50% of p(ES). A wide range among p(ES) reflected a large sampling error of these estimates. QTL frequency distributions and comparison of estimated QTL effects indicated a low precision of QTL localization and an upward bias in the absolute values of estimated QTL effects from ES. CV with data from three QTL studies reported in the literature yielded similar results as those obtained with maize testcrosses. We therefore recommend CV for obtaining asymptotically unbiased estimates of p and consequently a realistic assessment of the prospects of MAS.