Evaluation of nuclear and mitochondrial phylogenetics for the subtyping of Cyclospora cayetanensis.

Cyclospora cayetanensis is an enteric coccidian parasite responsible for gastrointestinal disease transmitted through contaminated food and water. It has been documented in several countries, mostly with low-socioeconomic levels, although major outbreaks have hit developed countries. Detection methods based on oocyst morphology, staining, and molecular testing have been developed. However, the current MLST panel offers an opportunity for enhancement, as amplification of all molecular markers remains unfeasible in the majority of samples. This study aims to address this challenge by evaluating two approaches for analyzing the genetic diversity of C. cayetanensis and identifying reliable markers for subtyping: core homologous genes and mitochondrial genome analysis. A pangenome was constructed using 36 complete genomes of C. cayetanensis, and a haplotype network and phylogenetic analysis were conducted using 33 mitochondrial genomes. Through the analysis of the pangenome, 47 potential markers were identified, emphasizing the need for more sequence data to achieve comprehensive characterization. Additionally, the analysis of mitochondrial genomes revealed 19 single-nucleotide variations that can serve as characteristic markers for subtyping this parasite. These findings not only contribute to the selection of molecular markers for C. cayetanensis subtyping, but they also drive the knowledge toward the potential development of a comprehensive genotyping method for this parasite.

Population structure of the Salmonella enterica serotype Oranienburg reveals similar virulence, regardless of isolation years and sources.

Salmonella enterica serotype Oranienburg is a multi-host, ubiquitous, and prevalent Non-typhoidal Salmonella (NTS) in subtropical rivers, particularly in sediments; little studied so far possible the adaptation and establishment of this microorganism based on its genetic content. This study was focused on the first five genomes of S. Oranienburg in sediments through whole-genome sequencing (WGS) and 61 river water genomes isolated in previous studies. Results showed an open pangenome with 5,594 gene clusters (GCs), and the division of their categories showed; 3,303 core genes, 741 persistent genes, 1,282 accessory genes, and 268 unique genes. Additionally, it showed three main subclades within the same serotype and showed a conserved genetic content, suggesting the display of different adaptation strategies to its establishment. Nine genes for antimicrobial resistance were detected: aac (6') - Iy, H-NS, golS, marA, mdsABC, mdtK, and sdiA, and a mutation in the parC gene p. T57S generating a resistance. In addition, virulence genes and pathogenicity islands (SPI's) were analyzed, finding 92 genes and an identity above 80 % in the SPI's 1 to 5, and the centisomes 54 and 63. The environmental strains of S. Oranienburg do not represent a concern as multidrug resistance (MDR) bacterium; however, virulence genes remain a potential health risk. This study contributes to understanding its adaptation to aquatic environments in Mexico.

Genomic Characterization of Twelve Lytic Bacteriophages Infecting Midgut Bacteria of Aedes aegypti.

Mosquito-borne diseases such as malaria and dengue are global severe public health threats. Due to the lack of efficient control methods, alternative approaches to decreasing arboviral transmitted diseases are prioritized to reduce morbidity and mortality in every endemic region. Mosquito midgut bacteria play an essential role in physiological development, fitness, and the arthropods´ vectorial capacity. Bacteriophages are viruses that infect bacteria and are considered a promising biocontrol method by eliminating midgut microbiota that plays an essential role in mosquitoes´ health. Here, we isolate and identify 22 bacteria from mosquito´s midgut belonging to the genera Mesobacillus, Enterobacter, Klebsiella, Microbacterium, Micrococcus, Pantoea, Serratia, and Staphylococcus, mainly. Twelve phages with lytic activity against Enterobacter, Klebsiella, and Pantoea were also isolated. All 12 phages showed a double-stranded DNA genome, ranging from 36,790 to 149,913 bp, and were taxonomically classified as members of the Drexlerviridae family, Molineuxvirinae, Studiervirinae, and Vequintavirinae subfamilies. Open reading frames associated with phage structure, packing, host lysis, DNA metabolism, and additional functions were predicted in all 12 phage genomes, while tRNAs were predicted in five phage genomes. In addition, the life cycle was predicted as virulent for the 12 phages, and no antibiotic resistance, virulence, allergenic, or lysogenic genes were found in either genome. These findings suggest that the 12 phages have biocontrol potentials; however, it is necessary to elucidate specific bacterial host's roles and then the phages' ability to serve as effective vector control.