High frequency of multidrug-resistant Escherichia coli from cattle in the Cerrado and Pantanal biomes of Brazil.

The indiscriminate use of antimicrobials has led to the emergence of resistant bacteria, especially pathogenic strains of Escherichia coli, which are associated with diseases in animals and humans. The aim of the present study was to characterize E. coli isolates in calves with regards to the presence of virulence genes and investigate the resistance of the isolates to different antimicrobials. Between 2021 and 2023, 456 fecal samples were collected from calves in the Pantanal and Cerrado biomes of the state of Mato Grosso do Sul, Brazil. All samples were subjected to microbiological analysis and disc diffusion antibiogram testing. The polymerase chain reaction method was used to detect virulence genes. Bacterial growth was found in 451 of the 456 samples and biochemically identified as Escherichia coli. All 451 isolates (100 %) exhibited some phenotypic resistance to antimicrobials and 67.62 % exhibited multidrug resistance. The frequency of multidrug-resistant isolates in the Cerrado biome was significantly higher than that in the Pantanal biome (p = 0.0001). In the Cerrado, the most common pathotype was Shiga toxin-producing Escherichia coli (STEC) (28 %), followed by toxigenic Escherichia coli (ETEC) (11 %), enterohemorrhagic Escherichia coli (EHEC) (8 %) and enteropathogenic Escherichia coli (EPEC) (2 %). In most cases, the concomitant occurrence of pathotypes was more common, the most frequent of which were ETEC + STEC (33 %), ETEC + EHEC (15 %) and ETEC + EPEC (3 %). The STEC pathotype (30 %) was also found more frequently in the Pantanal, followed by EHEC (12 %), ETEC (9 %) and EPEC (6 %). The STEC pathotype had a significantly higher frequency of multidrug resistance (p = 0.0486) compared to the other pathotypes identified. The frequency of resistance was lower in strains from the Pantanal biome compared to those from the Cerrado biome. Although some factors are discussed in this paper, it is necessary to clarify the reasons for this difference and the possible impacts of these findings on both animal and human health in the region.

Modification of stimulated lacrimal gland flow by sympathetic nerve impulses in rabbit.

This study was undertaken to determine if sympathetic nerve impulses modify lacrimal gland fluid (LGF) flow, which was continuously recorded from a cannula in the excretory duct of the lacrimal gland in rabbits anesthetized with pentobarbital sodium. The preganglionic trunk of the superior cervical ganglion was stimulated with electrical stimuli during pilocarpine-induced and reflexly induced secretion. Stimuli equal to or 6-8 times stronger than the intensity that produced maximal pupil dilation caused inhibition followed by poststimulus enhancement of LGF flow when the prestimulus LGF flow was greater than 3.0 mul/min. When the prestimulus LGF flow was less than 0.8 mul/min, the stronger stimulation enhanced LGF flow but the weaker stimulation produced inhibition followed by poststimulus enhancement of LGF flow. Although no measurements of lacrimal gland blood flow were made, the alterations in these responses, which occurred during alpha- and beta-adrenergic blockade, were consistent with the changes in sympathetically induced blood flow that occur during alpha- and beta-blockade in other organs.