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Bartonella spp. are fastidious, gram-negative intracellular bacteria that are transmitted to humans by insect vectors. The genus includes 12 species associated with human infection: B. henselae, B. quintana, B. bacilliformis, [...]

To understand the genetic drivers of immune recognition and evasion in colorectal cancer, we analyzed 1,211 colorectal cancer primary tumor samples, including 179 classified as microsatellite instability-high (MSI-high). This set includes The Cancer Genome Atlas colorectal cancer cohort of 592 samples, completed and analyzed here. MSI-high, a hypermutated, immunogenic subtype of colorectal cancer, had a high rate of significantly mutated genes in important immune-modulating pathways and in the antigen presentation machinery, including biallelic losses of B2M and HLA genes due to copy-number alterations and copy-neutral loss of heterozygosity. WNT/β-catenin signaling genes were significantly mutated in all colorectal cancer subtypes, and activated WNT/β-catenin signaling was correlated with the absence of T-cell infiltration. This large-scale genomic analysis of colorectal cancer demonstrates that MSI-high cases frequently undergo an immunoediting process that provides them with genetic events allowing immune escape despite high mutational load and frequent lymphocytic infiltration and, furthermore, that colorectal cancer tumors have genetic and methylation events associated with activated WNT signaling and T-cell exclusion.Significance: This multi-omic analysis of 1,211 colorectal cancer primary tumors reveals that it should be possible to better monitor resistance in the 15% of cases that respond to immune blockade therapy and also to use WNT signaling inhibitors to reverse immune exclusion in the 85% of cases that currently do not. Cancer Discov; 8(6); 730-49. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 663.

Staphylococcus aureus is a facultative intracellular pathogen of human macrophages, which facilitates chronic infection. The genotypes, pathways, and mutations influencing that phenotype remain incompletely explored. Here, we used two distinct strategies to ascertain S. aureus gene mutations affecting pathogenesis in macrophages. First, we analyzed isolates collected serially from chronic cystic fibrosis (CF) respiratory infections. We found that S. aureus strains evolved greater macrophage invasion capacity during chronic human infection. Bacterial genome-wide association studies (GWAS) identified 127 candidate genes for which mutation was significantly associated with macrophage pathogenesis in vivo. In parallel, we passaged laboratory S. aureus strains in vitro to select for increased infection of human THP-1 derived macrophages, which identified 15 candidate genes by whole-genome sequencing. Functional validation of candidate genes using isogenic transposon mutant knockouts and CRISPR interference (CRISPRi) knockdowns confirmed virulence contributions from 37 of 39 tested genes (95%) implicated by in vivo studies and 7 of 10 genes (70%) ascertained from in vitro selection, with one gene in common to the two strategies. Validated genes included 17 known virulence factors (39%) and 27 newly identified by our study (61%), some encoding functions not previously associated with macrophage pathogenesis. Most genes (80%) positively impacted macrophage invasion when disrupted, consistent with the phenotype readily arising from loss-of-function mutations in vivo. This work reveals genes and mechanisms that contribute to S. aureus infection of macrophages, highlights differences in mutations underlying convergent phenotypes arising from in vivo and in vitro systems, and supports the relevance of S. aureus macrophage pathogenesis during chronic respiratory infection in CF. Additional studies will be needed to illuminate the exact mechanisms by which implicated mutations affect their phenotypes. Author summary: Staphylococcus aureus is a significant cause of disease and can cause chronic infections that are extremely difficult to treat. One of the reasons that S. aureus persists so effectively in the human body is its ability to enter and survive within macrophages, which protects the bacteria from immune clearance and antibiotic therapies. A better understanding of the genes and mechanisms that S. aureus uses to infect macrophages could lead to new, more effective treatments for chronic infection. Here, we identified gene mutations associated with improved macrophage pathogenesis in S. aureus by studying isolates from chronic respiratory infection in vivo and using a laboratory macrophage model in vitro. We identified multiple, previously unknown genes and functions that can influence S. aureus macrophage pathogenesis. [ABSTRACT FROM AUTHOR]

Purpose: The goal of this preliminary study is to describe the vaginal microbiome of transgender and gender nonbinary (TGNB) individuals using nonculture-based techniques. TGNB individuals may undergo gender-affirming surgical procedures, which can include the creation of a neovagina. Little is known about microbial species that comprise this environment in states of health or disease. Methods: In this pilot study, vaginal swabs were self-collected from 15 healthy self-identified TGNB participants (age 26–69 years) and 8 cisgender comparator participants (age 27–50 years) between 2017 and 2018. Next-generation 16S ribosomal RNA sequencing was used to profile individual bacterial communities from all study samples. Results: The TGNB cohort demonstrated significantly higher intraindividual (alpha) diversity than the cisgender group (p=0.0003). Microbial species commensal to the gut and skin were identified only in specimens from TGNB participants. Although Lactobacillus species were dominant in all cisgender comparator samples, they were found at low relative abundance (≤3%) in TGNB samples. Conclusion: In this study, specimens collected from neovaginas showed increased alpha diversity and substantially different composition compared with natal vaginas. In contrast to natal vaginas, neovaginas were not dominated by Lactobacillus, but were hosts to many microbial species. Studies that help to improve our understanding of the neovaginal microbiome may enable clinicians to differentiate between healthy and diseased neovaginal states. [ABSTRACT FROM AUTHOR]

Bacterial and fungal co-infections are reported complications of coronavirus disease 2019 (COVID-19) in critically ill patients but may go unrecognized premortem due to diagnostic limitations. We compared the premortem with the postmortem detection of pulmonary co-infections in 55 fatal COVID-19 cases from March 2020 to March 2021. The concordance in the premortem versus the postmortem diagnoses and the pathogen identification were evaluated. Premortem pulmonary co-infections were extracted from medical charts while applying standard diagnostic definitions. Postmortem co-infection was defined by compatible lung histopathology with or without the detection of an organism in tissue by bacterial or fungal staining, or polymerase chain reaction (PCR) with broad-range bacterial and fungal primers. Pulmonary co-infection was detected premortem in significantly fewer cases (15/55, 27%) than were detected postmortem (36/55, 65%; p < 0.0001). Among cases in which co-infection was detected postmortem by histopathology, an organism was identified in 27/36 (75%) of cases. Pseudomonas, Enterobacterales, and Staphylococcus aureus were the most frequently identified bacteria both premortem and postmortem. Invasive pulmonary fungal infection was detected in five cases postmortem, but in no cases premortem. According to the univariate analyses, the patients with undiagnosed pulmonary co-infection had significantly shorter hospital (p = 0.0012) and intensive care unit (p = 0.0006) stays and significantly fewer extra-pulmonary infections (p = 0.0021). Bacterial and fungal pulmonary co-infection are under-recognized complications in critically ill patients with COVID-19. [ABSTRACT FROM AUTHOR]

Microsatellite instability (MSI), the spontaneous loss or gain of nucleotides from repetitive DNA tracts, is a diagnostic phenotype for gastrointestinal, endometrial, and colorectal tumors, yet the landscape of instability events across a wider variety of cancer types remains poorly understood. To explore MSI across malignancies, we examined 5,930 cancer exomes from 18 cancer types at more than 200,000 microsatellite loci and constructed a genomic classifier for MSI. We identified MSI-positive tumors in 14 of the 18 cancer types. We also identified loci that were more likely to be unstable in particular cancer types, resulting in specific instability signatures that involved cancer-associated genes, suggesting that instability patterns reflect selective pressures and can potentially identify novel cancer drivers. We also observed a correlation between survival outcomes and the overall burden of unstable microsatellites, suggesting that MSI may be a continuous, rather than discrete, phenotype that is informative across cancer types. These analyses offer insight into conserved and cancer-specific properties of MSI and reveal opportunities for improved methods of clinical MSI diagnosis and cancer gene discovery., Author(s): Ronald J Hause [1]; Colin C Pritchard [2]; Jay Shendure (corresponding author) [1, 3]; Stephen J Salipante (corresponding author) [2] MSI is a molecular tumor phenotype resulting from genomic [...]