[Class 1 integrons in Enterobacteriaceae and its association with multidrug resistance and conjugative plasmids]

The prevalence of antimicrobial resistance genes is a cause of concern. The combination of antimicrobial resistance genes and mobile genetic elements leads to their widespread presence in different bacterial species, in which integrons are a new and important element. We studied the presence of integrons in 123 unrelated enterobacteria and identified them in 20.3% of the strains. The combination of integrons and multidrug resistance was shown to be statistically significant (p <0.001). Integron-positive isolates were statistically (p <0.05) more likely to be resistant to amoxicillin-clavulanic acid, quinolones and trimethoprim-sulfamethoxazole. All the integrons were identified in conjugative plasmids. The prevalence of integrons increased from 21.2% in 1992-1994 to 72% in 1995-1997 (p <0.001). The aacC1 and aacC2 genes were identified in 80% of the integrons. The relationship between integrons and conjugative plasmids is a matter of concern because it could contribute to the dissemination of antimicrobial resistance genes among different bacterial populations.