Study On Relationship Between Pseudomonas Aeruginosa Integrons And Antibiotic-resistance In Respiratory Infection

Objective To survey the antibiotic-resistance of isolates of Pseudomonas aeruginosa from respiratory infection and the distribution of classâ… ,â…¡andâ…¢integrons in Pseudomonas aeruginosa and to investigate the characterization of integrons and gene cassette arrays. To analyze the association between gene cassettes and resistance phenotype as well as between integrons and multi-drug resistance and to explore the mechanism of integron-associated multi-drug resistance in these strains. Methods Antibiotic susceptibility of 97 strains of Pseudomonas aeruginosa were performed by using bioMerieux VITEK 2.Integrons were detected by PCR using degenerate primers targeted to 5 'conserved regions of classâ… ,â…¡andâ…¢integrase genes, The class of the integron was determined by analyzing integrase PCR products by restriction fragment length polymorphism(RFLP) following digestion using Hinf I restriction enzyme. The variable region of integron was amplified by long fragment PCR ,and the PCR products were restricted with Hinf I. Three representative products were purified and sequenced. Results Resistant rates of 97 strains of Pseudomonas aeruginosa against 16 kinds of antibiotic ranged from 4.2% to 100%, 72(74.2%) isolates were multi-drug resistant(resistance to over 3 antibiotics). Integron was detected in 20/97(20.6%) Pseudomonas aeruginosa,which all were classâ… integrons as PCR-RFLP analysis, no classâ…¡a ndâ…¢integrons were detected. Seventeen of the 20 strains contained three kinds of gene cassettes:979bp,1833bp and 2337bp.These cassettes included dfrl7 and dhfrXII(genes for dihydrofolate reductase) ,aadA2, aadA5, aadB and aac (6) -â…¡(which were aminoglycoside-modifying enzyme genes), blaCARB-8(which was carboxyl Penicillin Resistance genes). The rate of drug resistance in isolates of integron positive was generally higher than that of in the integron negative strains. Integrons were significantly associated with multi-drug resistance to certain antibiotic. Conclusions High drug resistance was found in isolates of Pseudomonas aeruginosa from respiratory infection; Gene Cassetes in integron are significantly associated with old antimicrobial such as trimethoprim and early aminoglycosides. Integrons are associated with antibiotic-resistance and multi-drug resistance in Pseudomonas aeruginosa.