β-lactam antibiotics are a key element in the treatment of bacterial infections. However, the excessive use of these antibiotics has contributed to the emergence of β-lactam-resistant enterobacteria, including Escherichia coli. One of the main challenges facing the public health sector is antibacterial resistance (ABR), mainly due to limited options in its pharmacological treatment. Currently, extended-spectrum β-lactamases (ESBLs) present an alarming situation, as there is an increase in morbidity and mortality rates, prolonged hospital stays, and increased costs for sanitary supplies, which involve not only humans but also the environment and animals, especially animals destined for food production. This review presents an analysis of the prevalence of ESBL-producing E. coli and its distribution in different animal sources throughout the world, providing an understanding of the association with resistance and virulence genes, as well as perceiving the population structure of E. coli.

In this study, two strains of Bdellovibrio were isolated from soil samples using the culture‐dependent technique and two members of the family Enterobacteriaceae (Klebsiella sp. and Salmonella sp.) as prey. The Bdellovibrio strains were bacteriolytic, plaque‐forming, and highly motile gram‐negative bacteria. We identified and confirmed the Bdellovibrio strains using microscopy, PCR amplification, and sequencing of the 16S rRNA gene. They were observed to be different strains based on hit locus and prey range analyses. Here, the first report on Bdellovibrio strains isolated from soil in Mexico corroborates earlier report indicating that populations of Bdellovibrio found in soil are heterogeneous thereby the need to identify the various strains.

Aedes aegypti, is the major dengue vector and a worldwide public health threat combated basically by chemical insecticides. In this study, the vectorial competence of Ae. aegypti co-infected with a mildly virulent Metarhizium anisopliae and fed with blood infected with the DENV-2 virus, was examined. The study encompassed three bioassays (B). In B1 the median lethal time (LT₅₀) of Ae. aegypti exposed to M. anisopliae was determined in four treatments: co-infected (CI), single-fungus infection (SF), single-virus infection (SV) and control (C). In B2, the mortality and viral infection rate in midgut and in head were registered in fifty females of CI and in SV. In B3, the same treatments as in B1 but with females separated individually were tested to evaluate the effect on fecundity and gonotrophic cycle length. Survival in CI and SF females was 70% shorter than the one of those in SV and control. Overall viral infection rate in CI and SV were 76 and 84% but the mortality at day six post-infection was 78% (54% infected) and 6% respectively. Survivors with virus in head at day seven post-infection were 12 and 64% in both CI and SV mosquitoes. Fecundity and gonotrophic cycle length were reduced in 52 and 40% in CI compared to the ones in control. Fungus-induced mortality for the CI group was 78%. Of the survivors, 12% (6/50) could potentially transmit DENV-2, as opposed to 64% (32/50) of the SV group, meaning a 5-fold reduction in the number of infective mosquitoes. This is the first report on a fungus that reduces the vectorial capacity of Ae. aegypti infected with the DENV-2 virus. Dengue is a worldwide public health problem. There is not an effective vaccine yet; the chemical struggle against its transmitter, the mosquito Aedes aegypti, is onerous and erratic, and the community participation to eliminate vector breeding sites is unconfident. Here, we examined mosquitoes fed on human blood mixed with the Dengue virus, by exposure to the fungus Metarhizium anisopliae, to test whether the fungus halts the viral dissemination from midgut to head in co-infected (CI) insects. We found an overall viral infection rate in CI mosquitoes of 76% but infected or not, most (78%) died before or at day six post-infection; only six (12%) out of 50, survivors had virus in head and were potentially infectious at day seven post-infection. A higher infection (84%) was observed in single-virus infected mosquitoes, but they suffered only 6% mortality after 6 days and 32 (64%) survivors tested positive for virus in head after 7 days. Survival, fecundity and ovaric cycle of CI mosquitoes were reduced in 70, 52 and 40% in comparison to the ones of control. Therefore, if the fungus caused a 5-fold reduction in the number of infectious mosquitoes, it has potential to be evaluated against the Dengue transmitter in field.

ESKAPE bacteria represent a group of opportunistic bacterial pathogens that display widespread antimicrobial resistance, including resistance to the last-line antibiotics, thereby posing a significant clinical implication globally. Anthropogenic activities, such as wastewater from hospitals, livestock farms, crop fields, and wastewater treatment plants, contribute to the dissemination of antimicrobial-resistant bacterial pathogens into the environment. Surface water sources, including river waters, act as critical points of discharge for wastewater, pollutants, antibiotic-resistant bacteria (ARB), and antibiotic-resistant genes (ARG). These environmental factors, along with others, facilitate the dissemination and survival of ARBs, as well as promote the exchange of ARGs. Therefore, it is crucial to comprehend the current environmental landscape concerning the prevalence and persistence of resistant bacteria, particularly those belonging to the ESKAPE group. This review aims to provide a comprehensive overview of the current dissemination and characterization of ESKAPE bacteria in surface water and wastewater sources.

There are ~240 species of Culicidae in Mexico, of which some are vectors of arthropod-borne viruses such as Zika virus, dengue virus, chikungunya virus, and West Nile virus. Thus, the identification of mosquito feeding preferences is paramount to understanding of vector–host–pathogen interactions that, in turn, can aid the control of disease outbreaks. Typically, DNA and RNA are extracted separately for animal (insects and blood meal hosts) and viral identification, but this study demonstrates that multiple organisms can be analyzed from a single RNA extract. For the first time, residual DNA present in standard RNA extracts was analyzed by DNA barcoding in concert with Sanger and next-generation sequencing (NGS) to identify both the mosquito species and the source of their meals in blood-fed females caught in seven sylvan communities in Chiapas State, Mexico. While mosquito molecular identification involved standard barcoding methods, the sensitivity of blood meal identification was maximized by employing short primers with NGS. In total, we collected 1,634 specimens belonging to 14 genera, 25 subgenera, and 61 morphospecies of mosquitoes. Of these, four species were new records for Mexico (Aedes guatemala, Ae. insolitus, Limatus asulleptus, Trichoprosopon pallidiventer), and nine were new records for Chiapas State. DNA barcode sequences for >300 bp of the COI gene were obtained from 291 specimens, whereas 130 bp sequences were recovered from another 179 specimens. High intraspecific divergence values (>2%) suggesting cryptic species complexes were observed in nine taxa:Anopheles eiseni(5.39%),An. pseudopunctipennis(2.79%),Ae. podographicus(4.05%),Culex eastor(4.88%),Cx. erraticus(2.28%),Toxorhynchites haemorrhoidalis(4.30%),Tr. pallidiventer(4.95%),Wyeomyia adelpha/Wy. guatemala(7.30%), andWy. pseudopecten(4.04%). The study increased the number of mosquito species known from 128 species to 138 species for Chiapas State, and 239 for Mexico as a whole. Blood meal analysis showed thatAedes angustivittatusfed on ducks and chicken, whereasPsorophora albipesfed on humans.Culex quinquefasciatusfed on diverse hosts including chicken, human, turkey, and Mexican grackle. No arbovirus RNA was detected by reverse transcriptase–polymerase chain reaction in the surveyed specimens. This study demonstrated, for the first time, that residual DNA present in RNA blood meal extracts can be used to identify host vectors, highlighting the important role of molecular approaches in both vector identification and revealing host–vector–pathogen interactions.

Cotesia flavipes Cameron (Hymenoptera: Braconidae), is a gregarious larval endoparasitoid of the sugarcane borer, Diatraea saccharalis Fabricius (Lepidoptera: Crambidae). The aim of this research was to analyze cellular immunosuppression of D. saccharalis parasitized by C. flavipes in terms of encapsulation, melanization, and hemocyte nodule formation. The encapsulation assay was done 1 and 6 days after parasitoid oviposition. In addition, the susceptibility of parasitized and nonparasitzed larvae to Bacillus thuringiensis HD 73 strain was assessed. 3, 12, and 24 h after bead injection; the percentages of encapsulation were significantly higher in unparasitized larvae compared to larvae parasitized 1 and 6 days after oviposition. Interestingly, there was a significant reduction in numbers of beads encapsulated at 1 day after oviposition compared to 6 days, and unparasitized larvae. The percentage of melanized beads decreased significantly in parasitized larvae compared to control. There was a reduction in the number of nodules in parasitized larvae compared to unparasitized controls. Larvae that were injected with polyndavirus 24 h before beads were injected showed significantly reduced encapsulation responses relative to control larvae. The D. saccharalis parasitized by C. flavipes exhibited higher susceptibility to B. thuringiensis. These results suggest that parasitization induced host immunosuppression, and the immunosuppression factors could impair the defense capacity against microbial pathogens -causing an increase in pathogen susceptibility.