| Congresso Brasileiro de Microbiologia 2023 | Resumo: 143-1 | ||||
Resumo:Salmonella 1,4,[5],12:i:- was the third most prevalent serovar isolated from human infections and the eighth most prevalent serovar isolated from non-human sources from 2004 to 2020 in São Paulo, Brazil. However, there is a lack of studies that characterized isolates of this serovar in this country. Therefore, the aims of this study were to determine the antimicrobial resistance profiles, to molecularly type and to analyze the survivability in different stress conditions of S. 1,4,[5],12:i:- strains isolated from humans and non-humans sources from 1983 to 2020 in Brazil. The susceptibility testing against 13 antimicrobials was performed by the disk diffusion method for 113 strains. In phenotypically fluoroquinolone resistant strains, plasmidial resistance genes and mutations in quinolone resistance-determining regions were searched. Molecular typing was performed for 40 selected strains by MLST. In addition, for the acid stress tolerance assay, 40 strains were resuspended in sodium citrate buffer pH 7.0 (control) and pH 4.5 (stress) and for the oxidative stress tolerance assay 40 strains were resuspended in saline 0.8% (control) and saline 0.8% supplemented with 15 mM H2O2 (stress). Control and stress aliquots were taken after 10 min and 1 hour in both assays. Of the total of 113 strains studied, 54.87% strains were resistant to at least one tested antimicrobial. The highest resistance rates found were against ampicillin (51.33%), nalidixic acid (39.82%) and tetracycline (38.05%). Moreover, 39 (34.51%) strains were classified as multidrug resistant. The nine fluoroquinolones resistant strains showed the gyrA mutation and the qnrB gene presence. All strains isolated from humans and non-human sources were typed as ST19 by MLST and survived to acid stress after 10 minutes and 1 hour of exposure. In oxidative stress, all 40 strains survived after 10 minutes and 36 survived after 1 hour of exposure. In conclusion, multidrug resistant strains were detected and are worrying being an alert for the importance of constant monitoring of resistance. All strains studied descend from a common precursor belonging to ST19, suggesting a closer phylogenetic relationship to S. Typhimurium. Finally, the studied strains isolated from human and non-human sources tolerated successfully some unfavorable conditions found in the human gastro-intestinal tract. Palavras-chave: Monophasic Salmonella, Antimicrobial resistance, Acid stress, Oxidative stress, Multilocus Sequence Type Agência de fomento:CAPES and FAPESP | |||||