Integron-Mediated Multidrug and Quinolone Resistance in Extended-Spectrum β-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae

Despite intensive care and treatment strategies, the development of antibiotic resistance to empirical drugs is concerning.
The aim of this study was to characterize extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae for integron-mediated quinolone resistance and multidrug resistance (MDR).
In this cross-sectional study, 71 E. coli and 63 K. pneumoniae clinical isolates underwent antibiotic susceptibility testing with the Kirby-Bauer method, followed by ESBL phenotypic screening with the combination disc method. The isolates were then genotypically characterized with PCR for the presence of integrons and the gyrA, parC, blaCTX-M-3, blaTEM, and blaSHV genes. Resistance to antibiotics was confirmed by sequencing.
K. pneumoniae was a potent ESBL producer (71.4%) in comparison to E. coli (57.7%). The predominant ESBL genotypes in E. coli and K. pneumoniae confirmed by sequencing were blaCTX-M-15 (67.60%) and blaSHV-1 (80.95%), respectively. Imipenem was the only antibiotic active against the ESBL-producing isolates. Approximately 54% of the isolates exhibited MDR patterns. MDR was more frequently related to the presence of blaCTX-M-3 in comparison to other genotypes. The prevalence of class 1 integrons was 15 (45.4%) and 22 (66.6%) of the E. coli and K. pneumonia isolates, respectively. Within the ESBL group, a class 1 genetic element was associated with the blaCTX-M-3 genotype in E. coli (36.58%) and K. pneumoniae (51.11%). Overall, almost half of the ESBL producers, irrespective of genus, were simultaneously resistant to quinolones. The simultaneous presence of class 1 and 2 integrons in quinolone-resistant isolates was the most frequent observation.
The high prevalence of multidrug and ESBL-mediated resistance is a therapeutic concern. The co-emergence of ESBLs and quinolone resistance in E. coli and K. pneumoniae suggests the preservation of the power of antibiotics in the face of the antibiotic-resistance crisis.