Structural Diversity of Class 1 Integrons in Multiresistant Strains of Escherichia coli Isolated from Patients in a Hospital in Mexico City

Abstract

Since a decade, Escherichia coli has been considered an important nosocomial pathogen due to the high number of isolates multiresistant to antimicrobials reported worldwide. In clinical and environmental strains, transposons, plasmids, and integrons are currently considered the principal genetic elements responsible for the acquisition of antibiotic resistance through horizontal transfer. The objective of this research was to correlate the resistance to antibiotics of E. coli clinical strains with the presence class I integrons. In the present study, one hundred E. coli strains were isolated and tested for susceptibility and resistance to antimicrobials. Class 1 integrons were detected by PCR, and the arrangement of gene cassettes was determined by sequencing. Twenty two strains were found to carry Class 1 integrons. Sequence analysis of the variable regions revealed the presence of several gene cassettes, such as dihydrofolate reductases (dfr2d, dfrA17, and dhfrXVb), adenylyl transferases (aadA2, addA5, and addA22), and chloramphenicol efflux pump (cmlA), and oxacillinase (bla OXA-1 ). The dfrA17-addA5 arrangement prevailed upon other integrons in the study. This is the first report of the presence of the dfr2d and dhfrXVb-aadA2 cassette arrangements in a Class 1 integrons from clinical strains of E. coli. In most of the strains, it was found a direct relationship between genetic arrangements and resistance phenotypes. Four integrons were detected in plasmids that might be involved in the resistance genes transfer to other bacteria of clinical importance. Our results confirm the presence of Class 1 integrons and their essential role in the dissemination of resistance cassettes among E. coli strains.

Multidrug- and Extensively Drug-Resistant Uropathogenic Escherichia coli Clinical Strains: Phylogenetic Groups Widely Associated with Integrons Maintain High Genetic Diversity

“…coli strains are the most frequently reported, followed by class 2 integrons (Poey and Laviña, 2014). A total of 24.2% of class 1 integrons in Mexican E. coli strains from different clinical sources were associated with MDR (Acosta-Pérez et al, 2015); similar data were obtained in our study. The highest presence of class 1 integrons was associated with phylogenetic groups D and B2 in MDR- and XDR-UPEC strains; however, several studies described variable results regarding the association of integrons and phylogenetic groups (Gündogdu et al, 2011; Zeighami et al, 2015).…”

“…Sequencing the variable region of class 1 and 2 integrons from MDR- and XDR-UPEC strains revealed the presence of genes encoding the antibiotic modifying enzymes aad A1, aad B, aac C, ant 1, dfr A1, and dfr A17. MDR- and XDR-UPEC strains with resistance to SXT and GM antibiotics were mainly associated with class 1 and 2 integrons, as described by other authors (Solberg et al, 2006; Márquez et al, 2008; El-Najjar et al, 2010; Soleimani et al, 2014; Acosta-Pérez et al, 2015; Yahiaoui et al, 2015). Class 3 integrons are part of the soil/freshwater proteobacteria group, have a poor occurrence rate and were not identified in this study (Deng et al, 2015).…”

“…Genetic diversity has been widely used to characterize populations of UPEC strains associated with several diseases of the urinary tract (Luo et al, 2012; Acosta-Pérez et al, 2015; Morales-Espinosa et al, 2016). The recurrence of UTIs at HIMFG was associated with several clones in the MDR-UPEC strains of phylogenetic groups D and B2, which are responsible for a majority of persistent UTIs.…”

Epidemiology, Environmental Risks, Virulence, and Resistance Determinants of Klebsiella pneumoniae From Dairy Cows in Hubei, China

“…The resistance of STR is mainly mediated by strA and strB and correlation analysis shows that the resistance of the STR of K. pneumoniae in this study may be more related to strB. It has been reported that tetA and floR / cmlA mediate the efflux of tetracycline and florfenicol, respectively, which can pump the drug out of the cell and reduce the intracellular drug concentration to generate resistance ( Acosta-Pérez et al, 2015 ; Wang et al, 2018 ; Graesbøll et al, 2019 ). Notably, tetA and floR are the most frequently observed AMR genes in K. pneumoniae resistant to tetracycline and amide alcohols, respectively, which are consistent with the study by Nobrega et al (2021) .…”