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Exploring Copper (II) and Nickel (II) complexes for the control of antimicrobial-resistant Campylobacter jejuni and Escherichia coli

2026-05-01T06:17:58Z

Title: Exploring Copper (II) and Nickel (II) complexes for the control of antimicrobial-resistant Campylobacter jejuni and Escherichia coli Abstract: Campylobacter jejuni and Escherichia coli are among the main pathogens associated with foodborne diseases, particularly those originating from poultry. The dissemination of multidrug-resistant strains and their ability to form biofilms favor the persistence of these microorganisms in industrial environments and reduce the effectiveness of conventional antimicrobials and sanitizers. In this context, this thesis aimed to evaluate the potential of two copper(II) complexes, [Cu(tta)(bipy)NO₃] and [Cu(tta)(phen)NO₃], and two nickel(II) complexes, [Ni(η²-NO₃)(bta)(phen)] and [Ni(η²-NO₃)(btacl)(phen)], as alternatives for the control of antimicrobial-resistant C. jejuni and E. coli, integrating phenotypic, genomic, and structural approaches. The thesis was organized into three chapters, with Chapter 1 dedicated to the theoretical framework and Chapters 2 and 3 structured as scientific articles. In Chapter 2, four metal complexes were evaluated against five resistant Campylobacter jejuni isolates. All isolates were classified as strong biofilm formers and exhibited a broad genomic repertoire, including 134 virulence genes and multiple determinants associated with resistance to antimicrobials, metals, and biocides. The complexes significantly reduced bacterial viability and biofilm formation, with particular emphasis on the [Ni(η²NO₃)(bta)(phen)] complex, which showed the lowest minimum bactericidal concentration (6.25 µg/mL) and promoted pronounced disruption of the extracellular matrix. Metabolomic analysis identified 408 compounds belonging to 14 chemical classes, revealing alterations consistent with oxidative stress, metabolic imbalance, and impairment of cellular integrity. In Chapter 3, ten Escherichia coli isolates from the poultry production chain were evaluated. Four isolates (40%) were classified as strong biofilm formers, and all exhibited a multidrug-resistant profile, with seven distinct resistance phenotypes. Genomic characterization revealed 28 antimicrobial resistance determinants, 280 virulence genes, 168 genes associated with resistance to metals and biocides, as well as 13 plasmid replicons. The complexes showed bactericidal activity against both planktonic (1.56–100 µg/mL) and sessile cells (25–400 µg/mL), again with superior performance of the [Ni(η²NO₃)(bta)(phen)] complex. Overall, the results demonstrate that metal complexes, particularly nickel(II)-based compounds, have high potential for the control of resistant bacteria associated with biofilms, contributing to the development of innovative strategies within the One Health framework.

influência da condição corporal pré-parto na dinâmica do parto e intervenção manual em fêmeas suínas: avaliação por caliper

2026-03-07T06:30:00Z

Title: influência da condição corporal pré-parto na dinâmica do parto e intervenção manual em fêmeas suínas: avaliação por caliper Abstract: The purpose of this research was to evaluate the impact of pre-partum body condition score, measured using the Caliper, on the occurrence of dystocia and the effects of manual intervention associated with the duration of farrowing. Body condition scores were measured in sows using the Caliper, pre-partum and during the first three weeks of lactation. The variables were subjected to analysis of variance and Tukey's test, with a significance level of 5%. The results showed that touch was associated with increased farrowing duration and a higher incidence of stillbirths, even though sows in this group showed less body condition score loss during lactation, possibly due to post-partum therapeutic support. On the other hand, pre-partum body condition score did not significantly influence farrowing duration, number of live births, and stillbirths. Greater body condition score loss was observed among fat sows, suggesting greater mobilization of energy reserves throughout lactation. Therefore, the management of sows should prioritize good body condition at farrowing, reduction of unnecessary obstetric interventions, and efficient therapeutic support for recovery, prioritizing the well-being of the sow.

Efeito do estresse por calor no desempenho reprodutivo de matrizes suínas nos trópicos e avaliação do limiar de ITU

2026-02-26T06:26:16Z

Title: Efeito do estresse por calor no desempenho reprodutivo de matrizes suínas nos trópicos e avaliação do limiar de ITU Abstract: First, the study aimed to model and estimate the impact of the maximum temperature–humidity index (THImax) on the number of stillbirths in sows and to calculate the stress–comfort ratio (S/C). A total of 36,880 farrowings from sows in a commercial farm in Brazil were analyzed. Females were grouped according to parity as gilts, primiparous sows, sows with 2–5 parities, and sows with ≥6 parities. THImax on the day of farrowing was classified as ≤74 (thermal comfort), 75–78 (mild stress), 79–82 (moderate stress), and >82 (severe stress). The effect of THImax on the daily number of stillbirths was estimated using quasi-Poisson regression. The mean number of stillbirths per farrowing and per THImax category was analyzed by ANOVA, and the S/C ratio was subsequently calculated according to THImax categories. Out of a total of 1,826 days, 14.95% were classified as thermal comfort days. Multiparous sows (≥2 parities) showed a higher number of daily stillbirths under THImax >82, whereas primiparous sows showed higher values under THI <74. According to the S/C ratio (severe/comfort), increases in stillbirths of 20% in gilts, 7% in primiparous sows, 14% in sows with 2–5 parities, and 19% in sows with ≥6 parities were observed. The quasi-Poisson model indicated an increase in daily stillbirths in multiparous sows (≥2 parities) under THImax >82, and an S/C ratio greater than 1 across all parity groups, indicating an increased mean number of stillbirths per farrowing, particularly under severe heat stress conditions. In the second study, the objective was to model and estimate the effects of air temperature (Ta) and relative humidity (RH) on respiratory rate (RR), rectal temperature (RT), and surface temperature (ST) of sows, and to assess whether the current THI threshold underestimates or overestimates heat stress under tropical production conditions. A total of 98 sows from a commercial farm in Brazil were evaluated and grouped according to parity as gilts, primiparous sows, sows with 2–6 parities, and sows with 7–11 parities. The effects of environmental variables on thermophysiological responses were estimated using quasi-Poisson regression (RR) and Gaussian models (RT and ST). Increases in Ta and RH significantly affected RR, RT, and ST in sows with 2–6 parities, whereas in gilts, only ST was affected. When estimating RR, this variable was identified as the first physiological response to increase with rising Ta and RH in primiparous and multiparous sows (≥2 parities). In these groups, RR exceeded the physiological threshold (32 breaths·min⁻¹) while THI values were still below 74. In conclusion, heat stress affects sows differently according to parity, and the current THI threshold (74) underestimates the impact of heat stress on sows raised under tropical conditions.

Uso da técnica de Haste Intramedular Bloqueada (HIB) em fratura diafisária femoral em tamanduá bandeira (mymercophaga tridactyla): relato de caso

2026-03-03T19:55:28Z

Title: Uso da técnica de Haste Intramedular Bloqueada (HIB) em fratura diafisária femoral em tamanduá bandeira (mymercophaga tridactyla): relato de caso