Nanocomposites: silver nanoparticles and bacteriocins obtained from lactic acid bacteria against multidrug-resistant Escherichia coli and Staphylococcus aureus.

Drug-resistant bacteria such as Escherichia coli and Staphylococcus aureus represent a global health problem that requires priority attention. Due to the current situation, there is an urgent need to develop new, more effective and safe antimicrobial agents. Biotechnological approaches can provide a possible alternative control through the production of new generation antimicrobial agents, such as silver nanoparticles (AgNPs) and bacteriocins. AgNPs stand out for their antimicrobial potential by employing several mechanisms of action that can act simultaneously on the target cell such as the production of reactive oxygen species and cell wall rupture. On the other hand, bacteriocins are natural peptides synthesized ribosomally that have antimicrobial activity and are produced, among others, by lactic acid bacteria (LAB), whose main mechanism of action is to produce pores at the level of the cell membrane of bacterial cells. However, these agents have disadvantages. Nanoparticles also have limitations such as the tendency to form aggregates, which decreases their antibacterial activity and possible cytotoxic effects, and bacteriocins have a narrow spectrum of action, require high doses to be effective, and can be degraded by proteases. Given these limitations, nanoconjugates of these two agents have been developed that can act synergistically in the control of pathogenic bacteria resistant to antibiotics. This review focuses on knowing relevant aspects of the antibiotic resistance of E. coli and S. aureus, the characteristics of these new generation antibacterial agents, and their effect alone or forming nanoconjugates that are more effective against the multiresistant mentioned bacteria.

Metagenomic insights into plasmid-mediated antimicrobial resistance in poultry slaughterhouse wastewater: antibiotics occurrence and genetic markers.

Slaughterhouse wastewater represents important convergence and concentration points for antimicrobial residues, bacteria, and antibiotic resistance genes (ARG), which can promote antimicrobial resistance propagation in different environmental compartments. This study reports the assessment of the metaplasmidome-associated resistome in poultry slaughterhouse wastewater treated by biological processes, employing metagenomic sequencing. Antimicrobial residues from a wastewater treatment plant (WWTP) that treats poultry slaughterhouse influents and effluents were investigated through high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). Residues from the macrolide, sulfonamide, and fluoroquinolone classes were detected, the latter two persisting after the wastewater treatment. The genetic markers 16S rRNA rrs (bacterial community) and uidA (Escherichia coli) were investigated by RT-qPCR and the sul1 and int1 genes by qPCR. After treatment, the 16S rRNA rrs, uidA, sul1, and int1 markers exhibited reductions of 0.67, 1.07, 1.28, and 0.79 genes copies, respectively, with no statistical significance (p > 0.05). The plasmidome-focused metagenomics sequences (MiSeq platform (Illumina®)) revealed more than 100 ARG in the WWTP influent, which can potentially confer resistance to 14 pharmacological classes relevant in the human and veterinary clinical contexts, in which the qnr gene (resistance to fluoroquinolones) was the most prevalent. Only 7.8% of ARG were reduced after wastewater treatment, and the remaining 92.2% were associated with an increase in the prevalence of ARG linked to multidrug efflux pumps, substrate-specific for certain classes of antibiotics, or broad resistance to multiple medications. These data demonstrate that wastewater from poultry slaughterhouses plays a crucial role as an ARG reservoir and in the spread of AMR into the environment.

Novel chitosan-based hydrogels as promising wound dressing materials with advanced properties.

Herein, four different grafted chitosans were synthesized by covalent attachment of glycine, L-arginine, L-glutamic acid, or L-cysteine to the chitosan chains. All products were subsequently permethylated to obtain their corresponding quaternary ammonium salts to enhance the inherent antimicrobial properties of native chitosan. In all cases, transparent hydrogels with the following remarkable characteristics were obtained: i) high-water absorption capacity (32-44 g H2O per g of polymer), ii) viscoelastic behavior at low deformations, iii) flexibility when subjected to deformations and iv) stability over long time scales. All the permethylated derivatives successfully inhibited 100 % of the growth of S. aureus. They also exhibited higher antimicrobial activity against E. coli than native chitosan. The structure of the chemically crosslinked products was more stable under external perturbations than that of the physically crosslinked ones. Between the chemically crosslinked products, the permethylated glutamic acid-grafted chitosan exhibited a noteworthy higher water absorption capacity with respect to that modified with cysteine, which makes it the most promising material for various industrial applications, including biomedical and food industries. Regarding biomedical applications, this derivative met the required physicochemical criteria for wound dressings, which encourages the pursuit of biological studies necessary to ensure the safety of its use for this application.

Antibiotic resistant Escherichia coli strains in healthy pets from Tamaulipas, Mexico.

Antibiotic resistance constitutes a significant public health challenge, with diverse reservoirs of resistant bacteria playing pivotal roles in their dissemination. Among these reservoirs, pets are carrying antibiotic-resistant strains. The objective of this study was to assess the resistance profiles of Escherichia coli, and the prevalence of extended-spectrum ß-lactamase (ESBL) producing E. coli strains in dogs and cats from Tamaulipas, Mexico. A total of 300 stool samples (150 dogs and 150 cats) from healthy pets were subjected to analysis. Antibiotic susceptibility testing and the identification of ESBLs were carried out by disc diffusion method. The presence of resistance genes, class 1, 2, and 3 integrons (intI1, intI2, and intI3) and phylogroups was determined by PCR analysis. The findings reveal that 42.6% (128/300) of the strains exhibited resistance to at least one of the eight antibiotics assessed, and 18.6% (56/300) demonstrated multidrug resistance (MDR), that distributed across 69 distinct resistance patterns. Altogether 2.6% of E. coli strains (8/300) were confirmed as TEM and CTX-M type ESBL producers. These outcomes underscore the roles of dogs and cats in Tamaulipas as reservoirs for the dissemination of MDR and/or ESBL strains. The results underscore the necessity for conducting prevalence studies on ESBL-producing E. coli, forming a foundation for comprehending the present scenario and formulating strategies for the control and mitigation of this issue.

Ionically-crosslinked carboxymethyl chitosan scaffolds by additive manufacturing for antimicrobial wound dressing applications.

Chitosan chemical functionalization is a powerful tool to provide novel materials for additive manufacturing strategies. The main aim of this study was the employment of computer-aided wet spinning (CAWS) for the first time to design and fabricate carboxymethyl chitosan (CMCS) scaffolds. For this purpose, the synthesis of a chitosan derivative with a high degree of O-substitution (1.07) and water soluble in a large pH range allowed the fabrication of scaffolds with a 3D interconnected porous structure. In particular, the developed scaffolds were composed of CMCS fibers with a small diameter (< 60 µm) and a hollow structure due to a fast non solvent-induced coagulation. Zn2+ ionotropic crosslinking endowed the CMCS scaffolds with stability in aqueous solutions, pH-sensitive water uptake capability, and antimicrobial activity against Escherichia coli and Staphylococcus aureus. In addition, post-printing functionalization through collagen grafting resulted in a decreased stiffness (1.6 ± 0.3 kPa) and a higher elongation at break (101 ± 9 %) of CMCS scaffolds, as well as in their improved ability to support in vitro fibroblast viability and wound healing process. The obtained results encourage therefore further investigation of the developed scaffolds as antimicrobial wound dressing hydrogels for skin regeneration.

Variability in the acid adaptation of ten different O157:H7 and non-O157 Escherichia coli strains in orange juice and the impact on UV radiation resistance.

This study aimed to assess the impact of adaptation of ten strains of O157:H7 and non-O157 Escherichia coli to low pH (acid shock or slow acidification) and the effects of this exposure or not on the resistance of E. coli strains to UV radiation in orange juice (pH 3.5). The acid-shocked cells were obtained through culture in tryptic soy broth (TSB) with a final pH of 4.8, which was adjusted by hydrochloric, lactic, or citric acid and subsequently inoculated in orange juice at 4 °C for 30 days. No significant differences (p > 0.05) in survival in orange juice were observed between the serotypes O157:H7 and non-O157:H7 for acid-shocked experiments. After slow acidification, where the cells were cultured in TSB supplemented with glucose 1% (TSB + G), a significant increase (p < 0.05) in survival was observed for all strains evaluated. The D-values (radiation dose (J/cm2) necessary to decrease the microbial population by 90%) were determined as the inverse of the slopes of the regressions (k) obtained by plotting log (N/N0). The results show that among the strains tested, E. coli O157:H7 (303/00) and O26:H11 were the most resistant and sensitive strains, respectively. According to our results, the method of acid adaptation contributes to increasing the UV resistance for most of the strains tested.

Escherichia coli ST117: exploring the zoonotic hypothesis.

Extraintestinal pathogenic Escherichia coli (ExPEC) can lead to severe infections, with additional risks of increasing antimicrobial resistance rates. Genotypic similarities between ExPEC and avian pathogenic E. coli (APEC) support a possible role for a poultry meat reservoir in human disease. Some genomic studies have been done on the ST117 lineage which contaminates poultry meat, carries multidrug resistance, can be found in the human intestinal microbiota, and causes human extraintestinal disease. This study analyzed the genomes of 61 E. coli from Brazilian poultry outbreaks focusing on ST117, to further define its possible zoonotic characteristics by genotypic and phylogenomic analyses, along with 1,699 worldwide ST117 isolates originating from human, animal, and environment sources. A predominance of ST117 was detected in the Brazilian isolates (n = 20/61) frequently carrying resistance to critical antibiotics (>86%) linked to IncFII, IncI1, or IncX4 replicons. High similarities were found between IncX4 from Brazilian outbreaks and those from E. coli recovered from imported Brazilian poultry meat and human clinical cases. The ST117 phylogeny showed non-specificity according to host and continent and an AMR index score indicated the highest resistance in Asia and South America, with the latter statistically more resistant and overrepresented with resistance to extended-spectrum beta-lactamases (ESBL). Most ST117 human isolates were predicted to have a poultry origin (93%, 138/148). In conclusion, poultry is a likely source for zoonotic ExPEC strains, particularly the ST117 lineage which can also serve as a reservoir for resistance determinants against critical antibiotics encoded on highly transmissible plasmids. IMPORTANCE: Certain extraintestinal pathogenic Escherichia coli (ExPEC) are particularly important as they affect humans and animals. Lineages, such as ST117, are predominant in poultry and frequent carriers of antibiotic resistance, presenting a risk to humans handling or ingesting poultry products. We analyzed ExPEC isolates causing outbreaks in Brazilian poultry, focusing on the ST117 as the most detected lineage. Genomic comparisons with international isolates from humans and animals were performed describing the potential zoonotic profile. The Brazilian ST117 isolates carried resistance determinants against critical antibiotics, mainly on plasmids, in some cases identical to those carried by international isolates. South American ST117 isolates from all sources generally exhibit more resistance, including to critical antibiotics, and worldwide, the vast majority of human isolates belonging to this lineage have a predicted poultry origin. As the world's largest poultry exporter, Brazil has an important role in developing strategies to prevent the dissemination of multidrug-resistant zoonotic ExPEC strains.

Peptide PaDBS1R6 has potent antibacterial activity on clinical bacterial isolates and integrates an immunomodulatory peptide fragment within its sequence.

BACKGROUND: Resistant infectious diseases caused by gram-negative bacteria are among the most serious worldwide health problems. Antimicrobial peptides (AMPs) have been explored as promising antibacterial, antibiofilm, and anti-infective candidates to address these health challenges. MAJOR CONCLUSIONS: Here we report the potent antibacterial effect of the peptide PaDBS1R6 on clinical bacterial isolates and identify an immunomodulatory peptide fragment incorporated within it. PaDBS1R6 was evaluated against Acinetobacter baumannii and Escherichia coli clinical isolates and had minimal inhibitory concentration (MIC) values from 8 to 32 µmol L-1. It had a rapid bactericidal effect, with eradication showing within 3 min of incubation, depending on the bacterial strain tested. In addition, PaDBS1R6 inhibited biofilm formation for A. baumannii and E. coli and was non-toxic toward healthy mammalian cells. These findings are explained by the preference of PaDBS1R6 for anionic membranes over neutral membranes, as assessed by surface plasmon resonance assays and molecular dynamics simulations. Considering its potent antibacterial activity, PaDBS1R6 was used as a template for sliding-window fr agmentation studies (window size = 10 residues). Among the sliding-window fragments, PaDBS1R6F8, PaDBS1R6F9, and PaDBS1R6F10 were ineffective against any of the bacterial strains tested. Additional biological assays were conducted, including nitric oxide (NO) modulation and wound scratch assays, and the R6F8 peptide fragment was found to be active in modulating NO levels, as well as having strong wound healing properties. GENERAL SIGNIFICANCE: This study proposes a new concept whereby peptides with different biological properties can be derived by the screening of fragments from within potent AMPs.

Biomedical properties, characterization of seaweeds species and antimicrobial activity.

Marine organisms produce a variety of compounds with pharmacological activities. In order to better comprehend the medicinal value of five particular seaweed orders Ulvales (Ulva intestinalis), Bryopsidales (Codium decorticatum), Ectocarpales (Iyengaria stellata), Dictyotales (Spatoglossum aspermum) and Gigartinales (Hypnea musciformis), a bioactive analysis including the screening of phytochemical components, antioxidant and antimicrobial activities was the aim of the investigation. The species include U. intestinalis was collected from Sandspit, while C. decorticatum, I. stellata, S. aspermum, and H. musciformis were gathered from Buleji. These species evaluated for their ability to inhibit human infectious gram positive pathogens Staphylococcus aureus, Staphylococcus epidermidis as well as gram negative bacteria Escherichia coli. Additionally vegetable pathogen Fusarium oxysporum, and fruit pathogens (Aspergillus niger and Aspergillus flavus) were evaluated to determine the zone of inhibition. Two organic solvents, ethanol and methanol, were used to prepare seaweed extract. The disc diffusion method was utilized to quantify the zone of inhibition and the DPPH method was employed to measure the antioxidant activity. The study unveiled various phyto-constituents in the tested seaweeds, with flavonoids, tannins, and proteins found in all selected species, while saponins, terpenoids, and carbohydrates were absent in I. stellata and S. aspermum. Notably, ethanolic extracts of I. stellata and S. aspermum demonstrated superior higher antioxidant activity, with increasing percentages of inhibition from 1 to 6 mg/ml. Furthermore, the findings indicated that the ethanolic extract of U. intestinalis displayed the highest resistance against F. oxysporum and A. flavous among other seaweeds. Meanwhile, the ethanolic extract of C. decorticatum exhibited the highest resistance against A. Niger. Additionally, the ethanolic extract of I. stellata and H. musciformis displayed the highest resistance against the gram-negative bacteria E. coli and the gram-positive bacteria S. epidermidis, whereas the methanolic extract of U. intestinalis demonstrated the highest resistance against the gram-positive bacteria S. aureus. The findings of this investigation show that a range of bioactive compounds with antioxidant properties are involved in the antimicrobial activities of disease-causing pathogens.

Resistance to cephalosporins and quinolones in Escherichia coli isolated from irrigation water from the Rímac river in east Lima, Peru. / Resistencia a cefalosporinas y quinolonas en Escherichia coli aisladas de agua de riego del río Rímac en Lima Este, Perú.

OBJECTIVES.: To evaluate the presence and sensitivity to antimicrobials of Escherichia coli strains isolated from 24 irrigation water samples from the Rimac river of East Lima, Peru. MATERIALS AND METHODS.: The E. coli strains were identified by PCR. Antibiotic susceptibility was processed by the disk diffusion method. Genes involved in extended spectrum beta-lactamases (BLEE), quinolones and virulence were determined by PCR. RESULTS.: All samples exceeded the acceptable limits established in the Environmental Quality Standards for vegetable irrigation. Of the 94 isolates, 72.3% showed resistance to at least one antibiotic, 24.5% were multidrug resistant (MDR) and 2.1% were extremely resistant. The highest percentages of resistance were observed for ampicillin-sulbactam (57.1%), nalidixic acid (50%), trimethoprim-sulfamethoxazole (35.5%) and ciprofloxacin (20.4%). Among the isolates, 3.2% had a BLEE phenotype related to the bla CTX-M-15 gene. qnrB (20.4%) was the most frequent transferable mechanism of resistance to quinolones, and 2.04% had qnrS. It was estimated that 5.3% were diarrheagenic E. coli and of these, 60% were enterotoxigenic E. coli, 20% were enteropathogenic E. coli and 20% were enteroaggregative E. coli. CONCLUSIONS.: The results show the existence of diarrheogenic pathotypes in the water used for irrigation of fresh produce and highlight the presence of BLEE- and MDR-producing E. coli, demonstrating the role played by irrigation water in the dissemination of resistance genes in Peru.Motivation for the study. Aquatic systems, including irrigation water, have been identified as reservoirs of antimicrobial resistance, with few studies in Peru on the presence of Escherichia coli and their levels of virulence and antimicrobial resistance. Main findings. Our results show the presence of E. coli above the established standard for vegetable irrigation water, some with very high levels of antimicrobial resistance. Implications. The presence of ESBL-producing strains of extended-spectrum beta-lactamases and multidrug-resistant E. coli in irrigation water could contribute to the dissemination of resistance genes in Peru, posing a significant threat to public health.

Antimicrobial susceptibility profile of bacteria of the genus Aeromonas and Escherichia coli isolated from samples of yellow hake (Cynoscion acoupa).

The aim of this study was to evaluate the antimicrobial susceptibility profile of Aeromonas sp., and Escherichia coli isolated from samples of yellow hake (Cynoscion acoupa). We analyzed 53 Aeromonas spp. and four E. coli isolates. We observed increased resistance of E. coli to levofloxacin and sulfa-trimethoprim as well as resistance of Aeromonas spp. to ampicillin, amoxicillin-clavulanate, cefuroxime, and cefotaxime. The multiple antimicrobial resistance(MAR) index indicated multidrug resistance in 90.54% (n=48) of Aeromonas spp. isolates and in 50% (n=2) of E. coli isolates. One strain of Aeromonas spp. was resistant to all 11tested antimicrobials (MAR index = 1.00). In vitro,piperacillin + tazobactam was the most effective antimicrobial for E. coli,and cefepime and levofloxacin were the most effective antimicrobials for Aeromonas spp. Therefore, in case of illnesses caused by these microorganisms, these antimicrobials should be used. The multidrug resistance of Aeromonas spp. and E. coli in this study is elevated. This is worrisome considering the increase in bacteria resistant to multiple drugs, reducing the options for successful clinical antimicrobial use.

Analysis of in vitro expression of virulence genes related to antibiotic and disinfectant resistance in Escherichia coli as an emerging periodontal pathogen.

The collective involvement of virulence markers of Escherichia coli as an emerging pathogen associated with periodontitis remains unexplained. This study aimed to implement an in vitro model of infection using a human epithelial cell line to determine the virulome expression related to the antibiotic and disinfectant resistance genotype and pulse field gel electrophoresis (PFGE) type in E. coli strains isolated from patients with periodontal diseases. We studied 100 strains of E. coli isolated from patients with gingivitis (n = 12), moderate periodontitis (n = 59), and chronic periodontitis (n = 29). The identification of E. coli and antibiotic and disinfectant resistance genes was performed through PCR. To promote the expression of virulence genes in the strains, an in vitro infection model was used in the human epithelial cell line A549. RNA was extracted using the QIAcube robotic equipment and reverse transcription to cDNA was performed using the QuantiTect reverse transcription kit (Qiagen). The determination of virulence gene expression was performed through real-time PCR. Overall, the most frequently expressed adhesion genes among the isolated strains of gingivitis, moderate periodontitis, and chronic periodontitis were fimH (48%), iha (37%), and papA (18%); those for toxins were usp (33%); those for iron acquisition were feoB (84%), fyuA (62%), irp-2 (61%), and iroN (35%); those for protectins were traT (50%), KpsMT (35%), and ompT (28%); and those for pathogenicity islands were malX (45%). The most common antibiotic and disinfectant resistance genes among gingivitis, moderate periodontitis, and chronic periodontitis strains were sul-2 (43%), blaSHV (47%), blaTEM (45%), tet(A) (41%), dfrA1 (32%), marR-marO (57%), and qacEA1 (79%). The findings revealed the existence of a wide distribution of virulome expression profiles related to the antibiotic and disinfectant resistance genotype and PFGE type in periodontal strains of E. coli. These findings may contribute toward improving the prevention and treatment measures for periodontal diseases associated with E. coli.

Bacteria-Derived Cellulose Membranes Modified with Graphene Oxide-Silver Nanoparticles for Accelerating Wound Healing.

This study reports on the modification of bacterial cellulose (BC) membranes produced by static fermentation of Komagataeibacter xylinus bacterial strains with graphene oxide-silver nanoparticles (GO-Ag) to yield skin wound dressings with improved antibacterial properties. The GO-Ag sheets were synthesized through chemical reduction with sodium citrate and were utilized to functionalize the BC membranes (BC/GO-Ag). The BC/GO-Ag composites were characterized to determine their surface charge, morphology, exudate absorption, antimicrobial activity, and cytotoxicity by using fibroblast cells. The antimicrobial activity of the wound dressings was assessed against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The results indicate that the BC/GO-Ag dressings can inhibit ∼70% of E. coli cells. Our findings also revealed that the porous BC/GO-Ag antimicrobial dressings can efficiently retain 94% of exudate absorption after exposure to simulated body fluid (SBF) for 24 h. These results suggest that the dressings could absorb excess exudate from the wound during clinical application, maintaining adequate moisture, and promoting the proliferation of epithelial cells. The BC/GO-Ag hybrid materials exhibited excellent mechanical flexibility and low cytotoxicity to fibroblast cells, making excellent wound dressings able to control bacterial infectious processes and promote the fast healing of dermal lesions.

[Nine-year trend in Escherichia coli resistance to ciprofloxacin: cross-sectional study in a hospital in Colombia]. / Nueve años de tendencia en la resistencia a ciprofloxacina por Escherichia coli: estudio transversal en un hospital de Colombia.

Ciprofloxacin is a critically important antibiotic for human health. The increase of Escherichia coli resistance to ciprofloxacin is a global public health problem due to its importance in the treatment of complicated urinary tract infections and other serious infections; however, its prescription is high in the Colombian Caribbean. The objective was to determine the resistance trend of E. coli to ciprofloxacin in a Colombian hospital of high complexity. From antibiogram reports, isolates were categorized according to Clinical and Laboratory Standards Institute criteria for each year studied; proportions were calculated and differences in sensitivity were explored using the χ2 test. The Cochran-Armitage test was used to evaluate the resistance trend. Significance was considered when p-value ≤ 0.05. In total, 6,848 isolates were analyzed, and 49.31% resistance was found. According to origin, the highest resistance was in community samples (51.96% - 95%CI: 50.51; 53.41), and by type of sample, in skin and tissues (61.76% - 95%CI: 56.96; 66.35) and urine (48.97% - 95%CI: 47.71; 50.23). Increasing trends were observed for resistance per year (p < 0.0001), community samples (p = 0.0002) and urine (p < 0.0001). Resistance to ciprofloxacin is high and tends to increase in the community and in urine, exceeding the limit established for its use at the ambulatory level, which is of concern due to the high prescription of fluoroquinolones in the locality.

La ciprofloxacina es un antibiótico de importancia crítica para la salud humana. El aumento de la resistencia de Escherichia coli a ciprofloxacina es un problema de salud pública global por su importancia en el tratamiento de infecciones urinarias complicadas y otras infecciones graves; sin embargo, su prescripción es alta en el caribe colombiano. El objetivo fue determinar la tendencia de resistencia de E. coli a ciprofloxacina en un hospital colombiano de alta complejidad. A partir de reportes de antibiogramas, los aislados fueron categorizados según los criterios del Instituto de Normas Clínicas y de Laboratorio de los Estados Unidos para cada año estudiado; se calcularon proporciones y se exploraron diferencias en la sensibilidad con pruebas χ2. Se utilizó la prueba de Cochran-Armitage para evaluar la tendencia de la resistencia. Valores de p ≤ 0,05 se consideraron significativos. Se analizaron 6.848 aislados, encontrándose una resistencia de 49,31%. Según el origen, la resistencia más alta fue en muestras comunitarias (51,96% - IC95%: 50,51; 53,41), y por tipo de muestra, en piel y tejidos (61,76% - IC95%: 56,96; 66,35) y orina (48,97% - IC95%: 47,71; 50,23). Se halló una tendencia al aumento en la resistencia por año (p < 0,0001), en muestras comunitarias (p = 0,0002) y en orina (p < 0,0001). La resistencia a ciprofloxacina es alta y tiende al aumento en comunidad y en orina, superando el límite establecido para su uso a nivel ambulatorio, lo que es preocupante por la alta prescripción de fluoroquinolonas en la localidad.

A ciprofloxacina é um antibiótico extremamente importante para a saúde humana. O aumento da resistência da Escherichia coli à ciprofloxacina é um problema de saúde pública global devido à sua importância no tratamento de infecções complicadas do trato urinário e outras infecções graves; no entanto, sua prescrição é alta no caribe colombiano. O objetivo foi determinar a tendência de resistência da E. coli à ciprofloxacina em um hospital colombiano de alta complexidade. A partir de relatórios de antibiogramas, os isolados foram categorizados de acordo com os critérios do Instituto de Padrões Clínicos e Laboratoriais dos Estados Unidos para cada ano estudado; as proporções foram calculadas e as diferenças de sensibilidade foram exploradas com os testes χ2. O teste de Cochran-Armitage foi usado para avaliar a tendência de resistência. Os valores de p ≤ 0,05 foram considerados significativos. Um total de 6.848 isolados foi testado e foi encontrada uma taxa de resistência de 49,31%. Por origem, a resistência foi mais alta em amostras comunitárias (51,96% - IC95%: 50,51; 53,41) e, por tipo de amostra, em pele e tecidos (61,76% - IC95%: 56,96; 66,35) e urina (48,97% - IC95%: 47,71; 50,23). Foi encontrada uma tendência de aumento na resistência por ano (p < 0,0001), em amostras da comunidade (p = 0,0002) e na urina (p < 0,0001). A resistência à ciprofloxacina é alta e tende a aumentar na comunidade e na urina, excedendo o limite estabelecido para uso ambulatorial, o que é preocupante, dada a alta prescrição de fluoroquinolonas na localidade.

Optimizing ozone treatment for pathogen removal and disinfection by-product control for potable reuse at pilot-scale.

Reclaimed water poses environmental and human health risks due to residual organic micropollutants and pathogens. Ozonation of reclaimed water to control pathogens and trace organics is an important step in advanced water treatment systems for potable reuse of reclaimed water. Ensuring efficient pathogen reduction while controlling disinfection byproducts remains a significant challenge to implementing ozonation in reclaimed water reuse applications. This study aimed to investigate ozonation conditions using a plug flow reactor (PFR) to achieve effective pathogen removal/inactivation while minimizing bromate and N-Nitrosodimethylamine (NDMA) formation. The pilot scale study was conducted using three doses of ozone (0.7, 1.0 and 1.4 ozone/total organic carbon (O3/TOC) ratio) to determine the disinfection performance using actual reclaimed water. The disinfection efficiency was assessed by measuring total coliforms, Escherichia coli (E. coli), Pepper Mild Mottle Virus (PMMoV), Tomato Brown Rugose Fruit Virus (ToBRFV) and Norovirus (HNoV). The ozone CT values ranged from 1.60 to 13.62 mg min L-1, resulting in significant reductions in pathogens and indicators. Specifically, ozone treatment led to concentration reductions of 2.46-2.89, 2.03-2.18, 0.46-1.63, 2.23-2.64 and > 4 log for total coliforms, E. coli, PMMoV, ToBRFV, and HNoV, respectively. After ozonation, concentrations of bromate and NDMA increased, reaching levels between 2.8 and 12.0 µg L-1, and 28-40.0 ng L-1, respectively, for average feed water bromide levels of 86.7 ± 1.8 µg L-1 and TOC levels of 7.2 ± 0.1 mg L-1. The increases in DBP formation were pronounced with higher ozone dosages, possibly requiring removal/control in subsequent treatment steps in some potable reuse applications.

NIR-responsive nano-holed titanium alloy surfaces: a photothermally activated antimicrobial biointerface.

Among external stimuli-responsive therapy approaches, those using near infrared (NIR) light irradiation have attracted significant attention to treat bone-related diseases and bone tissue regeneration. Therefore, the development of metallic biomaterials sensitive to NIR stimuli is an important area of research in orthopaedics. In this study, we have generated in situ prism-shaped silver nanoparticles (p-AgNPs) in a biomorphic nano-holed TiO2 coating on a Ti6Al4V alloy (a-Ti6Al4V). Insertion of p-AgNPs does not disturb the periodically arranged sub-wavelength-sized unit cell on the a-Ti6Al4V dielectric structure, while they exacerbate its peculiar optical response, which results in a higher NIR reflectivity and high efficiency of NIR photothermal energy conversion suitable to bacterial annihilation. Together, these results open a promising path toward strategic bone therapeutic procedures, providing novel insights into precision medicine.

Multidrug-resistant Escherichia coli isolated from free-range chickens in the Caatinga biome.

Antimicrobial-resistant Escherichia coli is a global health challenge from a One Health perspective. However, data on its emergence in the Caatinga biome are limited. This biome is exclusive to the Brazilian Northeast and offers unique epidemiological conditions that can influence the occurrence of infectious diseases and antimicrobial resistance. In this study, the carriage proportion, antimicrobial susceptibility, and population structure of cephalosporin-resistant E. coli were assessed in 300 cloacal swab samples of free-range chickens from three Brazilian states covered by the Caatinga biome. The results showed that 44 (14.7%) samples were positive for cephalosporin-resistant E. coli, and Paraíba state had the highest frequency of isolates (68.2%). Genes encoding cephotaximase-Munich or ampicillin class C (AmpC) enzymes were identified in 30 (68.2%) and 8 (18.2%) isolates, respectively, comprising 31 E. coli isolates. Overall, molecular typing by genome restriction using XbaI endonuclease followed by pulsed-field gel electrophoresis revealed four clusters from two properties of Paraíba state composed by extended-spectrum ß-lactamase-producing and AmpC-producing E. coli carrying blaCTX-M-1-like and blaMIR-1/ACT-1 genes and belonging to different phylogenetic groups. There is a need to control antimicrobial resistance while taking into account the genetic diversity of the strains and their implications for animal and public health, especially in free-range chickens reared in the Brazilian Caatinga biome.

Bioemulsifier from sponge-associated bacteria reduces staphylococcal biofilm.

Biofilm formation is a major health concern and studies have been pursued to find compounds able to prevent biofilm establishment and remove pre-existing biofilms. While biosurfactants (BS) have been well-known for possessing antibiofilm activities, bioemulsifiers (BE) are still scarcely explored for this purpose. The present study aimed to evaluate the bioemulsifying properties of cell-free supernatants produced by Bacillaceae and Vibrio strains isolated from marine sponges and investigate their antiadhesive and antibiofilm activities against different pathogenic Gram-positive and Gram-negative bacteria. The BE production by the marine strains was confirmed by the emulsion test, drop-collapsing, oil-displacement, cell hydrophobicity and hemolysis assays. Notably, Bacillus cereus 64BHI1101 displayed remarkable emulsifying activity and the ultrastructure analysis of its BE extract (BE64-1) revealed the presence of structures typically observed in macromolecules composed of polysaccharides and proteins. BE64-1 showed notable antiadhesive and antibiofilm activities against Staphylococcus aureus, with a reduction of adherence of up to 100 % and a dispersion of biofilm of 80 %, without affecting its growth. BE64-1 also showed inhibition of Staphylococcus epidermidis and Escherichia coli biofilm formation and adhesion. Thus, this study provides a starting point for exploring the antiadhesive and antibiofilm activities of BE from sponge-associated bacteria, which could serve as a valuable tool for future research to combat S. aureus biofilms.

A hurdle strategy based on the combination of non-thermal treatments to control diarrheagenic E. coli in cheese.

This study aimed to assess the efficacy of a multi-hurdle process combining mild High Hydrostatic Pressure (HHP) treatments and Thyme Oil (TO) edible films as a non-thermal method to combat pathogenic E. coli (aEPEC and STEC) in raw cow's-milk cheese stored at 7 °C and packaged under modified atmosphere. Changes in headspace atmosphere of cheese packs and treatment effects on Lactic Acid Bacteria (LAB) counts and diarrheagenic E. coli strains (aEPEC and STEC) were evaluated over a 28 d storage period. The results demonstrated that the combined treatment exhibited the most significant antimicrobial effect against both strains compared to individual treatments, achieving reductions of 4.30 and 4.80 log cfu/g after 28 d of storage for aEPEC and STEC, respectively. Notably, the synergistic effect of the combination treatment resulted in the complete inactivation of intact cells for STEC and nearly completed inactivation for aEPEC by the end of the storage period. These findings suggest that the combination of HHP with selected hurdles could effectively enhance microbial inactivation capacity, offering promising alternatives for improving cheese safety without affecting the starter microbiota.

Green Synthesis of Silver Nanoparticles with Extracts from Kalanchoe fedtschenkoi: Characterization and Bioactivities.

In this work, the hexane, chloroform, and methanol extracts from Kalanchoe fedtschenkoi were utilized to green-synthesize silver nanoparticles (Kf1-, Kf2-, and Kf3-AgNPs). The Kf1-, Kf2-, and Kf3-AgNPs were characterized by spectroscopy and microscopy techniques. The antibacterial activity of AgNPs was studied against bacteria strains, utilizing the microdilution assay. The DPPH and H2O2 assays were considered to assess the antioxidant activity of AgNPs. The results revealed that Kf1-, Kf2-, and Kf3-AgNPs exhibit an average diameter of 39.9, 111, and 42 nm, respectively. The calculated ζ-potential of Kf1-, Kf2-, and Kf3-AgNPs were -20.5, -10.6, and -7.9 mV, respectively. The UV-vis analysis of the three samples demonstrated characteristic absorption bands within the range of 350-450 nm, which confirmed the formation of AgNPs. The FTIR analysis of AgNPs exhibited a series of bands from 3500 to 750 cm-1, related to the presence of extracts on their surfaces. SEM observations unveiled that Kf1- and Kf2-AgNPs adopted structural arrangements related to nano-popcorns and nanoflowers, whereas Kf3-AgNPs were spherical in shape. It was determined that treatment with Kf1-, Kf2-, and Kf3-AgNPs was demonstrated to inhibit the growth of E. coli, S. aureus, and P. aeruginosa in a dose-dependent manner (50-300 µg/mL). Within the same range, treatment with Kf1-, Kf2-, and Kf3-AgNPs decreased the generation of DPPH (IC50 57.02-2.09 µg/mL) and H2O2 (IC50 3.15-3.45 µg/mL) radicals. This study highlights the importance of using inorganic nanomaterials to improve the biological performance of plant extracts as an efficient nanotechnological approach.