Streambed immobilization controls the transport of antibiotic resistance genes in flowing water.

Antibiotic resistance is a serious global health issue, resulting in at least 1.2 million deaths in 2019. The environment is a potentially important reservoir of antibiotic resistance; however, the fate of Antibiotic Resistance Genes (ARGs) in the environment remains poorly characterized. One important environmental source of ARGs is manure used as a soil amendment. ARGs from manure may then enter nearby flowing waterbodies, where the factors governing their downstream transport remain unknown. To address this, we conducted experiments by spiking cattle manure in an artificial stream to estimate removal rates (k; m-1) for three ARGs (mefA, tetQ, and tetW) and a ruminant fecal marker (bacR). We then used a Stochastic Mobile-Immobile Model (SMIM) to separate the overall removal into two components, rs, and rh, corresponding to immobilizations in the surface (i.e., water column) and subsurface (i.e., streambed), respectively. Finally, we applied the SMIM across four model streams to predict the downstream travel distance of ARGs and bacR. Our results showed measurable removal for all targets in all experimental replicates (n = 3) and no differences were found in the removal rates among replicates for any target (ANCOVA; p > 0.05). We found that the removal of bacR was significantly lower than tetW (p < 0.05) and slightly lower than mefA (p = 0.088), while tetQ removal was slightly different from tetW's (p = 0.072). We also found that rh values were orders of magnitude larger than rs for ARGs and bacR (t-test; p < 0.05). These findings suggest that ARGs and bacR are being removed from the water column through immobilization reactions occurring in the streambed. Additionally, we predicted that the 90 % removal (or D90) of targets occurs within the first 500 m in all model streams except in a slow-flow pastoral stream, which required 1400 m of downstream transport for 90 % removal. Our findings and model stand out as promising tools to predict the fate of ARGs in streams and will contribute to improving and managing agricultural practices that employ animal manure.

Contribution of SARS-CoV-2 RNA shedding routes to RNA loads in wastewater.

A portion of those infected with SARS-CoV-2 shed the virus and its genetic material in respiratory fluids, saliva, urine, and stool, thus giving the potential to monitor for infections via wastewater. Wastewater surveillance efforts to date have largely assumed that stool shedding has been the primary source of SARS-CoV-2 RNA signal; however, there are increasing questions about the possible contribution of other shedding routes, with implications for wastewater surveillance design and feasibility. In this study we used clinical SARS-CoV-2 RNA shedding data and a Monte Carlo framework to assess the relative contribution of various shedding routes on SARS-CoV-2 RNA loads in wastewater. Stool shedding dominated total SARS-CoV-2 RNA load for community-level surveillance, with mean contributions more than two orders of magnitude greater than other shedding routes. However, RNA loads were more nuanced when considering building-level monitoring efforts designed to identify a single infected individual, where any shedding route could plausibly contribute a detectable signal. The greatest source of model variability was viral load in excreta, suggesting that future modeling efforts may be improved by incorporating specific modeling scenarios with precise SARS-CoV-2 shedding data, and beyond that wastewater surveillance must continue to account for large variability during data analysis and reporting. Importantly, the findings imply that wastewater surveillance at finer spatial scales is not entirely dependent on shedding via feces for sensitive detection of infections thus enlarging the potential use cases of wastewater as a non-intrusive surveillance methodology.

Intestinal epithelial Toll-like receptor 4 prevents metabolic syndrome by regulating interactions between microbes and intestinal epithelial cells in mice.

Little is known about the pathogenesis of metabolic syndrome, although Toll-like receptor 4 (TLR4) has been implicated. We investigated whether TLR4 in the intestinal epithelium regulates metabolic syndrome by coordinating interactions between the luminal microbiota and host genes that regulate metabolism. Mice lacking TLR4 in the intestinal epithelium (TLR4ΔIEC), but not mice lacking TLR4 in myeloid cells nor mice lacking TLR4 globally, developed metabolic syndrome; these features were not observed in TLR4ΔIEC mice given antibiotics. Metagenomic analysis of the fecal microbiota revealed differences between TLR4ΔIEC and wild-type mice, while meta-transcriptome analysis of the microbiota showed that intestinal TLR4 affected the expression of microbial genes involved in the metabolism of lipids, amino acids, and nucleotides. Genes regulated by peroxisome proliferator-activated receptors (PPARs) and the antimicrobial peptide lysozyme were significantly downregulated in TLR4ΔIEC mice, suggesting a mechanism by which intestinal TLR4 could exert its effects on the microbiota and metabolic syndrome. Supportingly, antibiotics prevented both downregulation of PPAR genes and the development of metabolic syndrome, while PPAR agonists prevented development of metabolic syndrome in TLR4ΔIEC mice. Thus, intestinal epithelial TLR4 regulates metabolic syndrome through altered host-bacterial signaling, suggesting that microbial or PPAR-based strategies might have therapeutic potential for this disease.

Viral metagenome analysis to guide human pathogen monitoring in environmental samples.

AIMS: The aim of this study was to develop and demonstrate an approach for describing the diversity of human pathogenic viruses in an environmentally isolated viral metagenome. METHODS AND RESULTS: In silico bioinformatic experiments were used to select an optimum annotation strategy for discovering human viruses in virome data sets and applied to annotate a class B biosolid virome. Results from the in silico study indicated that <1% errors in virus identification could be achieved when nucleotide-based search programs (BLASTn or tBLASTx), viral genome only databases and sequence reads >200 nt were considered. Within the 51,925 annotated sequences, 94 DNA and 19 RNA sequences were identified as human viruses. Virus diversity included environmentally transmitted agents such as parechovirus, coronavirus, adenovirus and aichi virus, as well as viruses associated with chronic human infections such as human herpes and hepatitis C viruses. CONCLUSIONS: This study provided a bioinformatic approach for identifying pathogens in a virome data set and demonstrated the human virus diversity in a relevant environmental sample. SIGNIFICANCE AND IMPACT OF THE STUDY: As the costs of next-generation sequencing decrease, the pathogen diversity described by virus metagenomes will provide an unbiased guide for subsequent cell culture and quantitative pathogen analyses and ensures that highly enriched and relevant pathogens are not neglected in exposure and risk assessments.

Cytomegalovirus viraemia has poor predictive value for the development of cytomegalovirus disease in patients with advanced HIV-infection.

OBJECTIVE: Cytomegalovirus (CMV) continues to be one of the most important opportunistic infections associated with human immunodeficiency virus (HIV) infection. This study investigated the value of CMV-viraemia in predicting the development of clinical CMV disease in patients with advanced HIV infection. METHODS: This was a prospective observational study performed over a 2-year period between 1994-96 in the Department of Infection and Tropical Medicine at Leicester Royal Infirmary. Adult HIV-positive patients attending a hospital clinic were included if they were CMV-seropositive with CD4 counts < or =50 cells/mm3. Subjects were seen at approximately 6-weekly intervals in the clinic and were reviewed by an experienced ophthalmologist. Serum for CMV PCR was taken and stored at regular intervals and qualitative and quantitative PCR was performed at the end of the study period. The value of PCR in predicting the development of CMV disease was then assessed. RESULTS: Twenty-six patients were followed up during the study period and 77 evaluable specimens were analysed for CMV PCR. Twenty-three (30%) samples were positive and 54 negative. Seven (27%) patients developed CMV disease (five retinitis alone, and two with retinitis and oesophagitis) during the study period. Viraemia was often intermittent and there was no significant difference in the proportions of patients with positive or negative tests who subsequently developed CMV disease. The sensitivity, specificity, positive and negative predictive values of the qualitative PCR were 71%, 47%, 33% and 82% respectively and 57%, 74%, 44% and 82% respectively for the quantitative PCR (>10(3) copies/ml). CONCLUSIONS: The results from this study, which was performed before the introduction of protease inhibitors, found that cytomegalovirus PCR was of limited clinical value in predicting the patients at greatest risk of developing CMV-disease and provided little useful prognostic information.

Retention and stability: a review of the literature.

Long-term posttreatment stability is an issue of great concern to all orthodontists. This article highlights the factors reported to play a role in posttreatment crowding and reviews the long-term retention studies evaluating the stability of various treatment modalities. Recommendations, based on well-documented basic principles, are made to try to insure greater posttreatment stability of our orthodontically treated cases.

Sellar and suprasellar hemangiopericytoma mimicking pituitary adenoma.

Hemangiopericytoma is a vascular neoplasm of variable and unpredictable malignancy, composed of proliferating capillary pericytes surrounding endothelial-lined tubes or sprouts. The histological appearance is diagnostic. The treatment of primary intracranial hemangiopericytoma is surgical excision, supplemented by radiotherapy. Local tumor recurrence after many years is common, and late and widespread metastasis can occur. Long-term follow-up is mandatory.

The "harlequin" sign and congenital Horner's syndrome.

When trying to establish the likely anatomical site (preganglionic or postganglionic) of a lesion causing congenital Horner's syndrome, the distribution of facial flushing (the "harlequin" sign), may be seen. In babies and young children, facial flushing is a relatively simple clinical sign to demonstrate, compared with facial sweating. In unilateral facial flushing the areas that do not flush are almost always identical to the anhidrotic areas. However, neither facial flushing nor testing the pupil reactions with pholedrine or hydroxyamphetamine can be relied on to predict the probable site of any lesion causing congenital Horner's syndrome. Two patients with congenital Horner's syndrome are presented which demonstrated the "harlequin" sign and in whom clinical examination and pharmacological testing gave conflicting evidence for localisation of the site of the causative lesion. The presentation of congenital Horner's syndrome should be investigated and include MRI or CT to exclude a serious underlying cause.