Discovery of new structure of class 1 integron in MDR Pseudomonas aeruginosa and its association with drugresistance

Abstract:

Abstract:［Objective］ To investigate the characteristics of classⅠintegrons among clinical multidrug-resistant Pseudomonas aeruginosa isolates，and to analyze the association between class Ⅰ integrons and multidrug resistance.［Methods］Pseudomonas aeruginosa strains were isolated from clinical samples，and the multidrug-resistant ones were picked out from these isolates．PCR assays were used to detect the variable regions of class Ⅰ integrons，and the resulting products were then digested with restriction enzyme Sau 3AⅠand sequenced． SPSS19. 0 software was used for statistical analysis.［Results］ Class Ⅰ integrons were detected in 27.3% of the clinical multidrug-resistant Pseudomonas aeruginosa isolates．Amplification of variable regions of class Ⅰ integrons revealed three different gene cassette arrays (1500，2300 and 4000 bp)，two of them were also found in other bacteria．These gene cassette arrays encoded aminoglycoside-modifying enzymes (aadA，aadB，aac(6')Ⅱ and aadA13)，β-lactamases (blaCARB8 and oxa10) and chloromycetin efflux pump (cmlA8). Analysis results suggested closely relationship between class Ⅰ integrons and aminoglycoside resistance.［Conclusion］We revealed three different gene cassette arrays in the clinical isolates of the multidrug-resistant Pseudomonas aeruginosa，and gene cassette array aadB-aac(6')Ⅱ-blaCARB8 was the most prevalent．The three gene cassette arrays all contained the aminoglycoside-resistant genes.