Genomic Surveillance of Ceftriaxone-Resistant Escherichia coli in Western New York Suggests the Extended-Spectrum ß-Lactamase bla CTX-M-27 Is Emerging on Distinct Plasmids in ST38.

Extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae pose significant treatment and infection prevention challenges. Escherichia coli sequence type (ST) 131 associated with the bla CTX-M-15 gene has been the dominant lineage of ESBL-producing E. coli in the US and worldwide. In this study, our objective was to determine the ß-lactamase profile, means of dissemination, prevalence, and the clonal identity of ESBL-producing E. coli in our region of Western New York. Whole-genome SNP-based phylogenomics was used to assess 89 ceftriaxone-resistant (CTR) E. coli. Isolates were collected from both inpatients and outpatients and from urine and sterile-sites over a 2 month period in 2017 or throughout the year, respectively. ST131 was the predominant ST (46.0%), followed by ST38 (15.7%). The bla CTX-M-15 gene was commonly found in 53.7% of ST131 isolates, whereas the bla CTX-M-27 gene was found in 26.8% of ST131, though was significantly associated with ST38, and was found in 71.4% of those strains. When compared to ST131, ST38 E. coli exhibited increased frequency of resistance to nitrofurantoin and decreased frequency of resistance to ciprofloxacin and ampicillin-sulbactam. Using Nanopore long-read sequencing technology, an analysis of the ESBL genetic context showed that the bla CTX-M-15 gene was chromosomal in 68.2% of ST131, whereas the bla CTX-M-27 gene was plasmid-borne in all ST131 and 90% of ST38 isolates. Notably, the bla CTX-M-27 gene in ST38 resided on highly-related (99.0-100.0% identity and 65.0-98.0% query coverage) conjugative IncF plasmids of distinct plasmid multi-locus sequence types (pMLSTs) from those in ST131. Furthermore, ST131 and ST38 were found to harbor different antibiotic resistance gene and virulence factor profiles. These findings raise the possibility of an emerging ESBL-producing E. coli lineage in our region.

Genome Sequence of a Facklamia hominis Isolate from a Patient with Urosepsis.

The genome sequence of a Facklamia hominis strain isolated from the urine of a patient with acute cystitis and sepsis is reported. The genome contains ermB and tet(M) genes, consistent with the isolate's phenotypic resistance to macrolides and tetracycline.

Immunoreceptor tyrosine-based inhibitory motif-dependent functions of an MHC class I-specific NK cell receptor.

Natural killer (NK) cells express MHC class I (MHC-I)-specific receptors, such as Ly49A, that inhibit killing of cells expressing self-MHC-I. Self-MHC-I also "licenses" NK cells to become responsive to activating stimuli and regulates the surface level of NK-cell inhibitory receptors. However, the mechanisms of action resulting from these interactions of the Ly49s with their MHC-I ligands, particularly in vivo, have been controversial. Definitive studies could be derived from mice with targeted mutations in inhibitory Ly49s, but there are inherent challenges in specifically altering a single gene within a multigene family. Herein, we generated a knock-in mouse with a targeted mutation in the immunoreceptor tyrosine-based inhibitory motif (ITIM) of Ly49A that abolished the inhibitory function of Ly49A in cytotoxicity assays. This mutant Ly49A caused a licensing defect in NK cells, but the surface expression of Ly49A was unaltered. Moreover, NK cells that expressed this mutant Ly49A exhibited an altered inhibitory receptor repertoire. These results demonstrate that Ly49A ITIM signaling is critical for NK-cell effector inhibition, licensing, and receptor repertoire development.

De novo assembly and transcriptome analysis of Plasmodium gallinaceum identifies the Rh5 interacting protein (ripr), and reveals a lack of EBL and RH gene family diversification.

BACKGROUND: Malaria parasites that infect birds can have narrow or broad host-tropisms. These differences in host specificity make avian malaria a useful model for studying the evolution and transmission of parasite assemblages across geographic ranges. The molecular mechanisms involved in host-specificity and the biology of avian malaria parasites in general are important aspects of malaria pathogenesis that warrant further examination. Here, the transcriptome of the malaria parasite Plasmodium gallinaceum was characterized to investigate the biology and the conservation of genes across various malaria parasite species. METHODS: The P. gallinaceum transcriptome was annotated and KEGG pathway mapping was performed. The ripr gene and orthologous genes that play critical roles in the purine salvage pathway were identified and characterized using bioinformatics and phylogenetic methods. RESULTS: Analysis of the transcriptome sequence database identified essential genes of the purine salvage pathway in P. gallinaceum that shared high sequence similarity to Plasmodium falciparum when compared to other mammalian Plasmodium spp. However, based on the current sequence data, there was a lack of orthologous genes that belonged to the erythrocyte-binding-like (EBL) and reticulocyte-binding-like homologue (RH) family in P. gallinaceum. In addition, an orthologue of the Rh5 interacting protein (ripr) was identified. CONCLUSIONS: These findings suggest that the pathways involved in parasite red blood cell invasion are significantly different in avian Plasmodium parasites, but critical metabolic pathways are conserved throughout divergent Plasmodium taxa.

Strain-specific variation in murine natural killer gene complex contributes to differences in immunosurveillance for urethane-induced lung cancer.

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related deaths worldwide and results from a complex interaction between carcinogen exposure and inherent susceptibility. Despite its prevalence, genetic factors that predispose to the development of lung cancer remain elusive. Inbred mouse models offer a unique and clinically relevant tool to study genetic factors that contribute to lung carcinogenesis due to the development of tumors that resemble human adenocarcinoma and broad strain-specific variation in cancer incidence after carcinogen administration. Here, we set out to investigate whether strain-specific variability in tumor immunosurveillance contributes to differences in lung cancer. Using bone marrow transplantation, we determined that hematopoietic cells from lung cancer-resistant mice could significantly impede the development of cancer in a susceptible strain. Furthermore, we show that this is not due to differences in tumor-promoting inflammatory changes or variability in immunosurveillance by the adaptive immune system but results from strain-specific differences in natural killer (NK) cell cytotoxicity. Using a newly discovered congenic strain of mice, we show a previously unrecognized role for strain-specific polymorphisms in the natural killer gene complex (NKC) in immunosurveillance for carcinogen-induced lung cancer. Because polymorphisms in the NKC are highly prevalent in man, our data may explain why certain individuals without obvious risk factors develop lung cancer whereas others remain resistant to the disease despite heavy environmental carcinogen exposure.

Effects of MHC class I alleles on licensing of Ly49A+ NK cells.

NK cells are innate immune lymphocytes that can react to cells lacking self-MHC class I. However, NK cells that cannot engage self-MHC through an inhibitory receptor are resistant to stimulation through their activation receptors. To become licensed (i.e., functionally competent to be triggered through its activation receptors), an NK cell must engage host MHC class I via a MHC class I-specific inhibitory receptor, such as a member of the murine Ly49 family. To explore potential determinants of NK cell licensing on a single Ly49 receptor, we have investigated the relative licensing impacts of the b, d, k, q, r, and s H2 haplotypes on Ly49A(+) NK cells. The results indicate that licensing is essentially analog but is saturated by moderate-binding MHC class I ligands. Interestingly, licensing exhibited a strong inverse correlation with a measure of cis engagement of Ly49A. Finally, licensing of Ly49A(+) NK cells was found to be less sensitive to MHC class I engagement than Ly49A-mediated effector inhibition, suggesting that licensing establishes a margin of safety against NK cell autoreactivity.