Comparative Genomic Analyses of Virulence and Antimicrobial Resistance in Citrobacter werkmanii, an Emerging Opportunistic Pathogen.

Citrobacter werkmanii is an emerging and opportunistic human pathogen found in developing countries and is a causative agent of wound, urinary tract, and blood infections. The present study conducted comparative genomic analyses of a C. werkmanii strain collection from diverse geographical locations and sources to identify the relevant virulence and antimicrobial resistance genes. Pangenome analyses divided the examined C. werkmanii strains into five distinct clades; the subsequent classification identified genes with functional roles in carbohydrate and general metabolism for the core genome and genes with a role in secretion, adherence, and the mobilome for the shell and cloud genomes. A maximum-likelihood phylogenetic tree with a heatmap, showing the virulence and antimicrobial genes' presence or absence, demonstrated the presence of genes with functional roles in secretion systems, adherence, enterobactin, and siderophore among the strains belonging to the different clades. C. werkmanii strains in clade V, predominantly from clinical sources, harbored genes implicated in type II and type Vb secretion systems as well as multidrug resistance to aminoglycoside, beta-lactamase, fluoroquinolone, phenicol, trimethoprim, macrolides, sulfonamide, and tetracycline. In summary, these comparative genomic analyses have demonstrated highly pathogenic and multidrug-resistant genetic profiles in C. werkmanii strains, indicating a virulence potential for this commensal and opportunistic human pathogen.

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.

Phylogenetic group and virulence profile classification in Escherichia coli from distinct isolation sources in Mexico.

Escherichia coli is a leading cause of human enteric diseases worldwide. The rapid and accurate causal agent identification to a particular source represents a crucial step in the establishment of safety and health measures in the affected human populations and would thus provide insights into the relationship of traits that may contribute for pathogen persistence in a particular reservoir. The objective of the present study was to characterize over two hundred E. coli strains from different isolation sources in Mexico by conducting a correspondence analysis to explore associations with the detected phylogenetic groups. The results indicated that E. coli strains, recovered from distinct sources in Mexico, were classified into phylogroups B1 (35.8%), A (27.8%), and D (12.3%) and were clustered to particular clades according to the predicted phylogroups. The results from correspondence analysis showed that E. coli populations from distinct sources in Mexico, belonging to different phylogroups, were not dispersed randomly and were associated with a particular isolation source. Phylogroup A was strongly associated with human sources, and the phylogroup B1 showed a significant relationship with food sources. Additionally, phylogroup D was also related to human sources. Phylogroup B2 was associated with herbivorous and omnivorous mammals. Moreover, common virulence genes in the examined E. coli strains, assigned to all phylogroups, were identified as essential markers for survival and invasion in the host. Although virulence profiles varied among the detected phylogroups, E. coli strains belonging to phylogroup D, associated with humans, were found to contain the largest virulence gene repertoire conferring for persistence and survival in the host. In summary, these findings provide fundamental information for a better characterization of pathogenic E. coli, recovered from distinct isolation sources in Mexico and would assist in the development of better tools for identifying potential transmission routes of contamination.