Characterization of Pc Promoter Variants of Class 1 Integrons in Escherichia coli Isolates from Poultry Meat

Abstract Integrons are important genetic elements implicated in acquisition and expression of antimicrobial resistance genes. Gene cassettes of class 1 integrons may be differently expressed depending on the Pc promoter variant. Thirty-four Escherichia coli isolates (carrying 38 class 1 integrons), recovered from poultry meat in previous studies in Tunisia and selected by their specific traits, were further characterized in this study. Integron promoter variants and the pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) of isolates were determined. Three types of promoter variants were identified among the 38 class 1 integrons (PcW, PcH1, and PcS); the weak promoters were the most predominant. A high clonal diversity of the E. coli strains was demonstrated by PFGE or by MLST. Fifteen PFGE profiles were detected among 19 integron-positive isolates of phylogroup B2, and 12 different sequence types were identified by MLST among the remaining 15 isolates (ST48, ST88, ST101, ST117, S...