Sepsis from the gut: the enteric habitat of bacteria that cause late-onset neonatal bloodstream infections.

BACKGROUND: Late-onset sepsis is a major problem in neonatology, but the habitat of the pathogens before bloodstream invasion occurs is not well established. METHODS: We examined prospectively collected stools from premature infants with sepsis to find pathogens that subsequently invaded their bloodstreams, and sought the same organisms in stools of infants without sepsis. Culture-based techniques were used to isolate stool bacteria that provisionally matched the bloodstream organisms, which were then genome sequenced to confirm or refute commonality. RESULTS: Of 11 children with late-onset neonatal bloodstream infections, 7 produced at least 1 stool that contained group B Streptococcus (GBS), Serratia marcescens, or Escherichia coli before their sepsis episode with provisionally matching organisms. Of 96 overlap comparison subjects without sepsis temporally associated with these cases, 4 were colonized with provisionally matching GBS or S. marcescens. Of 175 comparisons of stools from randomly selected infants without sepsis, 1 contained a GBS (this infant had also served as an overlap comparison subject and both specimens contained provisionally matching GBS). Genome sequencing confirmed common origin of provisionally matching fecal and blood isolates. The invasive E. coli were present in all presepticemic stools since birth, but gut colonization with GBS and S. marcescens occurred closer to time of bloodstream infection. CONCLUSIONS: The neonatal gut harbors sepsis-causing pathogens, but such organisms are not inevitable members of the normal microbiota. Surveillance microbiology, decolonization, and augmented hygiene might prevent dissemination of invasive bacteria between and within premature infants.

Effects of Walnut Consumption on Colon Carcinogenesis and Microbial Community Structure.

Walnuts are composed of a complex array of biologically active constituents with individual cancer-protective properties. Here, we assessed the potential benefit of whole walnut consumption in a mouse tumor bioassay using azoxymethane. In study 1, a modest reduction (1.3-fold) in tumor numbers was observed in mice fed a standard diet (AIN-76A) containing 9.4% walnuts (15% of total fat). In study 2, the effects of walnut supplementation was tested in the Total Western Diet (TWD). There was a significant reduction (2.3-fold; P < 0.02) in tumor numbers in male mice fed TWD containing 7% walnuts (10.5% of total fat). Higher concentrations of walnuts lacked inhibitory effects, particularly in female mice, indicating there may be optimal levels of dietary walnut intake for cancer prevention. Since components of the Mediterranean diet have been shown to affect the gut microbiome, the effects of walnuts were therefore tested in fecal samples using 16S rRNA gene sequencing. Carcinogen treatment reduced the diversity and richness of the gut microbiome, especially in male mice, which exhibited lower variability and greater sensitivity to environmental changes. Analysis of individual operational taxonomic units (OTU) identified specific groups of bacteria associated with carcinogen exposure, walnut consumption, and/or both variables. Correlation analysis also identified specific OTU clades that were strongly associated with the presence and number of tumors. Taken together, our results indicate that walnuts afford partial protection to the colon against a potent carcinogenic insult, and this may be due, in part, to walnut-induced changes to the gut microbiome. Cancer Prev Res; 9(8); 692-703. ©2016 AACR.

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.