1. The aim of this study was to compare the resistance pattern of thermophilic Campylobacter spp. isolated from conventional production (n = 34) and backyard poultry flocks (n = 36) from Rio de Janeiro State, Brazil. The disc diffusion method and statistical tests were used for investigation and analysis of the resistance pattern of Campylobacter spp. isolated from different rearing systems. 2. Antimicrobial resistance percentages to amoxycillin with clavulanic acid (AMC), ampicillin (AMP), ceftiofur (CTF), ciprofloxacin (CIP), enrofloxacin (ENO), erythromycin (ERI), gentamicin (GEN) and tetracycline (TET) were 32.4%, 44.1%, 67.6%, 97.1%, 82.4%, 26.5%, 5.9% and 38.2% in conventional production flocks respectively, while the backyard flock’s resistance levels were 0.0%, 13.9%, 69.4%, 100.0%, 91.7%, 5.6%, 0.0% and 16.7%, respectively. 3. Campylobacter spp. from conventional poultry production was more resistant to AMC, AMO, ERI and TET (P > 0.05) when compared to strains from backyard poultry. A higher frequency of resistance to fluoroquinolones (FLQ), CIP and ENO, was observed in strains from both systems, demonstrating the spread of resistant strains among poultry production environments.

Salmonella is one of the major foodborne pathogens worldwide. Domestic, wild animals, and a variety of food matrices can transmit Salmonella spp. to humanS. Here, we report the top 10 Salmonella serovars isolated from human sources between 2011 and 2020 and received in the National Reference Laboratory for Enteric DiseaseS. Serotyping was performed according to the Kauffman-White scheme. 3113 isolates related to human cases belonging to 61 serogroups were received in the NRL between 2011 and 2020. The purpose of this article is the identification of circulating serotypes as the first step to understanding the epidemiology, and then, with this information, take actions to mitigate and control this pathogen.

Salmonella Heidelberg is frequently found in poultry and poultry products and is associated with antimicrobial resistance strains and infections and mortality in humans. Whole-genome sequencing is used to monitor and understand epidemiological factors related to antimicrobial resistance. This study aimed to characterize the phenotypic resistance and sequence the whole genome of Salmonella Heidelberg strains isolated from poultry products in Brazil. Fourteen Salmonella Heidelberg strains isolated from whole broiler chicken carcasses and portions in Brazil between 2013 and 2019 were used in this study. Genus confirmation was performed by polymerase chain reaction. The disk diffusion test was conducted to assess the phenotypical antimicrobial susceptibility of the strains. Whole-genome sequencing was carried out to investigate the presence of antimicrobial resistance genes, plasmids, multilocus sequence typing, and virulence-associated genes. A high frequency of phenotypic resistance to cephalosporins, tetracyclines, and sulfonamides was detected. All strains had mutations in gyrA and parC and contained the genes tet(A), fosA7, and sul. The presence of genes originating from Yersinia pathogenicity islands was also detected. This study identified a high frequency of antimicrobial resistance in Salmonella Heidelberg strains from broilers slaughtered in different regions of Brazil, all belonging to the same sequence type (ST15) and associated with multiple resistance and virulence genes. The presence of the Yersinia high-pathogenicity island was detected, indicating potential virulence. These findings highlight the importance of continuously monitoring antimicrobial resistance to control and prevent foodborne infections and maintain the efficacy of treatments for human salmonellosis.

1. This study evaluated the minimal inhibitory concentration (MIC) of ciprofloxacin and the presence of plasmid-mediated quinolone resistance (PMQR) mechanisms in 97 nontyphoidal Salmonella spp. isolated from broilers and carcasses from three different regions in Brazil. The presence of mutations in quinolone resistance determination regions (QRDRS) was investigated in the ciprofloxacin-resistant strain by DNA sequencing. 2. Most of the Salmonella spp. (85.6%) had intermediate resistance to ciprofloxacin and only one isolate was resistant. MIC breakpoints ranged from ≤0.03 to 1 µg/ml and 67.01% of the strains had a MIC of 0.25 µg/ml (n=65). Thirteen strains (13.40%) were susceptible to ciprofloxacin with MIC ≤0.06 µg/ml. The qnrB gene was detected in eight isolates with intermediate resistance and in two susceptible strains. The other PMQR genes, qnrA, qnrC, qnrD, qnrS, qnrVC, aac(6′)-Ib, qepA, oqxAB and mutations in QRDR were not detected in any strain. 3. There was a high frequency of ciprofloxacin intermediate resistant Salmonella from broiler and broiler carcasses from Brazil. The presence of these strains in poultry and derived products poses a risk to public health.

Broiler chickens and derived products are a key source of Shiga toxin-producing Escherichia coli (STEC) in humans. This pathotype is responsible for causing severe episodes of diarrhea, which can progress to systemic complications. A rapid and accurate diagnosis of the disease, and early treatment of the infection with antimicrobials, can prevent it worsening. However, multidrug-resistant strains have potentially negative implications for treatment success. In this context, the aim of the present study was to isolate and identify multidrug-resistant STEC strains from broiler chickens and carcasses. Of 171 E. coli strains, isolated by conventional microbiological techniques and submitted to Polymerase Chain Reaction (PCR), for detection of stx1 and stx2 genes, 21.05% (36/171) were STEC pathotype, and most of them (66.67% - 24/36) carried both stx1 and eae genes. The multidrug resistance pattern was observed in 75% (27/36) of STEC strains. The presence of STEC in broiler chickens and carcasses reinforces that these sources may act as reservoirs for this pathotype. Multidrug-resistant bacteria contaminating animal products represent a public health issue because of the possibility of spread of multidrug-resistant determinants in the food chain and a higher risk of failure in human treatment when antimicrobials are needed.

Veterinarians play a critical role in antimicrobial stewardship, balancing the need for effective treatment with the growing threat of antimicrobial resistance. This study explores the factors influencing veterinarian antimicrobial prescription behavior, including clinical decision-making, professional experience, and external pressures. Using a cross-sectional survey distributed from February to August 2022, data were collected from 46 veterinarians regarding their prescribing habits, awareness of antimicrobial resistance (AMR), and continuing education participation. The results indicate that diagnostic tests and clinical signs are the primary drivers of antimicrobial selection with penicillin, sulfonamides and quinolones being the most frequently prescribed classes. While most respondents acknowledge the rising prevalence of AMR, they often attribute responsibility to other sectors. Continuing education significantly impacts prescribing behavior, with trained veterinarians demonstrating greater caution in their choices. Challenges in client communication remain a key barrier to effective antimicrobial stewardship. These findings highlight the need for enhanced educational initiatives, improved diagnostic accessibility, and strategic interventions to ensure responsible antimicrobial use in veterinary practice.