Cefalosporin resistance genes and antibacterial activity of Pereskia aculeata against ESBL- producing Escherichia coli isolated from broiler chickens

Abstract Antimicrobial resistance in Escherichia coli strains has contributed to the search for alternative antimicrobial products, such as plant extracts. The objective of this study was to evaluate the profile of cephalosporin-resistance genes in E. coli isolates with an extended-spectrum ß-lactamase (ESBL) production phenotype, and the phenolic composition and antibacterial activity of the ethanolic extract of Pereskia aculeata against strains isolated from 1-day-old and growing chickens. To determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the ethanolic extract of P. aculeata, E. coli isolates that exhibited an ESBL profile when isolated from either 1-day-old chicks or growing chickens were selected. The resistance genes blaCTX-M-1, blaCTX-M-2, blaCTX-M-8, and blaSHV were detected in a higher percentage of isolates from growing chickens. The P. aculeata extract was found to contain several phenolic compounds, with malic acid and rutin being predominant. Determination of MIC was only possible for two E. coli isolates (one from Broiler house A (growing chickens) and the other from Broiler house B (1-day-old chicks) - and for the standard strain E. coli ATCC 25922; in all cases, the MIC was 20 mg/mL. These findings indicate that E. coli isolates from both age groups carried cephalosporin-resistance genes and exhibit similar susceptibility to the P. aculeata extract, regardless of ESBL phenotype. These results highlight the need for further research into plant-based antimicrobials.