Molecular and Antimicrobial Susceptibility Characterization of Escherichia coli Isolates from Bovine Slaughterhouse Process.

Antimicrobials are routinely used in human and veterinary medicine. With repeated exposure, antimicrobials promote antibiotic resistance, which poses a threat to public health. In this study, we aimed to determine the susceptibility patterns, virulence factors, and phylogroups of E. coli isolates during the killing process in a bovine slaughterhouse. We analyzed 336 samples (from water, surfaces, carcasses, and feces), and 83.3% (280/336) were positive for E. coli. The most common phenotypic resistances that we detected were 50.7% (142/280) for tetracycline, 44.2% (124/280) for cephalothin, 34.6% (97/280) for streptomycin, and 36.7% (103/280) for ampicillin. A total of 82.4% of the isolates had resistance for at least one antimicrobial, and 37.5% presented multiresistance. We detected a total of 69 different phenotypic resistance patterns. We detected six other resistance-related genes, the most prevalent being tetA (22.5%) and strB (15.7%). The prevalence values of the virulence genes were 5.4% in hlyA, 1.4% in stx1, and 0.7% in stx2. The frequencies of the pathogenic strains (B2 and D) were 32.8% (92/280) and 67.1% (188/280) as commensals A and B1, respectively. E. coli isolates with pathogenic potential and multiresistance may represent an important source of dissemination and a risk to consumers.

First Record of the Rare Species Aeromonas lusitana from Rainbow Trout (Oncorhynchus mykiss, Walbaum): Comparative Analysis with the Existing Strains.

The species Aeromonas lusitana was first described in 2016 with five strains recovered from untreated water and vegetables from Portugal. Since then, no further records exist of this species. During a surveillance study on the presence of Aeromonas in fish farms in Mexico, a new strain (ESV-351) of the mentioned species isolated from a rainbow trout was recovered. It was identified because it clustered phylogenetically with the type strain of A. lusitana based on the analysis of the rpoD gene sequences. In the present study, phenotypic characteristics, antimicrobial resistance profiles, and the presence of putative virulence genes of this novel strain (ESV-351) were determined in parallel to the five isolates from the original species description. Phenotypic differential characteristics exhibited by A. lusitana ESV-351 depicted an evident similarity to the characteristics exhibited by the other evaluated strains. However, the novel strain was positive for the production of indole using conventional methods, while the rest of the strains, including the type strain, were negative for its production. Furthermore, intermediate resistance to ampicillin, amoxicillin-clavulanic acid and cephalothin was detected in both the novel and the type strain. Five different virulence-related genes were detected in the novel strain and in the previously described strains, with the type strain exhibiting the highest number of virulence-related genes. In addition to this, the genome of the novel strain (ESV-351) was sequenced and compared with the genomes from the type strain (A. lusitana CECT 7828T) and other Aeromonas spp. The genomic analysis defined Aeromonas tecta as the closest species to A. lusitana with a highly similar number of predicted proteins. The genomic size, the number of protein-encoding genes and the number of different tRNAs, among other characteristics, make it possible to propose that the ESV-351 strain could potentially have the capacity to adapt to different environments. Genome comparison of the ESV-351 strain with the type strain revealed that both possess a similar sequence of the citrate synthase gene. In addition to this finding, the chromosomal region containing the citrate synthase locus of the novel strain exhibits some similarity to the chromosomal region in the genome of the A. hydrophila type strain and other known human pathogens, such as Vibrio cholerae. This could suggest a possible virulence role for the citrate synthase gene in A. lusitana (ESV-351).

The Challenge of CRISPR-Cas Toward Bioethics.

Since determining the structure of the DNA double helix, the study of genes and genomes has revolutionized contemporary science; with the decoding of the human genome, new findings have been achieved, including the ability that humans have developed to modify genetic sequences in vitro. The discovery of gene modification mechanisms, such as the CRISPR-Cas system (Clustered Regularly Interspaced Short Palindromic Repeats) and Cas (CRISPR associated). Derived from the latest discoveries in genetics, the idea that science has no limits has exploded. However, improvements in genetic engineering allowed access to new possibilities to save lives or generate new treatment options for diseases that are not treatable by using genes and their modification in the genome. With this greater knowledge, the immediate question is who governs the limits of genetic science? The first answer would be the intervention of a legislative branch, with adequate scientific advice, from which the logical answer, bioethics, should result. This term was introduced for the first time by Van Rensselaer Potter, who in 1970 combined the Greek words bios and ethos, Bio-Ethik, which determined the study of the morality of human behavior in science. The approach to this term was introduced to avoid the natural tension that results from the scientific technical development and the ethics of limits. Therefore, associating the use of biotechnology through the CRISPR-Cas system and the regulation through bioethics, aims to monitor the use of techniques and technology, with benefits for humanity, without altering fundamental rights, acting with moral and ethical principles.

Analysis of CRISPR-Cas systems in Gardnerella suggests its potential role in the mechanisms of bacterial vaginosis.

Bacterial vaginosis (BV) is the principal cause of vaginal discharge among women, and it can lead to many comorbidities with a negative impact in women's daily activities. Despite the fact that the pathophysiological process of BV remains unclear, great advances had been achieved in determining consequences of the shift in the vaginal community, and it was defined that Gardnerella spp., plays a key role in the pathogenesis of BV. Interactions of vaginal phage communities and bacterial hosts may be relevant in eubiosis/dysbiosis states, so defense mechanisms in Gardnerella spp., against phage infections could be relevant in BV development. In this study, we analyzed CRISPR-Cas systems among the 13 Gardnerella species recently classified, considering that these systems act as prokaryotic immune systems against phages, plasmids, and other mobile genetic elements. In silico analyses for CRISPR-Cas systems mining over the 81 Gardnerella spp., strains genomes analyzed led to the identification of subtypes I-E and II-C. Spacers analyses showed a hypervariable region across species, providing a high resolution level in order to distinguish clonality in strains, which was supported with phylogenomic analyses based on Virtual Genomic Fingerprinting. Moreover, most of the spacers revealed interactions between Gardnerella spp., strains and prophages over the genus. Furthermore, virulence traits of the 13 species showed insights of potential niche specificity in the vaginal microbiome. Overall, our results suggest that the CRISPR-Cas systems in the genus Gardnerella may play an important role in the mechanisms of the development and maintenance of BV, considering that the Gardnerella species occupies different niches in the vaginal community; in addition, spacer sequences can be used for genotyping studies.

Horizontal Gene Transfer and Its Association with Antibiotic Resistance in the Genus Aeromonas spp.

The evolution of multidrug resistant bacteria to the most diverse antimicrobials known so far pose a serious problem to global public health. Currently, microorganisms that develop resistant phenotypes to multiple drugs are associated with high morbidity and mortality. This resistance is encoded by a group of genes termed 'bacterial resistome', divided in intrinsic and extrinsic resistome. The first one refers to the resistance displayed on an organism without previous exposure to an antibiotic not involving horizontal genetic transfer, and it can be acquired via mutations. The latter, on the contrary, is acquired exclusively via horizontal genetic transfer involving mobile genetic elements that constitute the 'bacterial mobilome'. This transfer is mediated by three different mechanisms: transduction, transformation, and conjugation. Recently, a problem of public health due to implications in the emergence of multi-drug resistance in Aeromonas spp. strains in water environments has been described. This is derived from the genetic material transfer via conjugation events. This is important, since bacteria that have acquired antibiotic resistance in natural environments can cause infections derived from their ingestion or direct contact with open wounds or mucosal tissue, which in turn, by their resistant nature, makes their eradication complex. Implications of the emergence of resistance in Aeromonas spp. by horizontal gene transfer on public health are discussed.