Characterized of class I integron in Acinetobacter baumannii isolated from upper respiratory tract.

Objective: To characterize the class I integron in Acinetobacter baumannii and to analyze the correlation between integron and drug resistance.

Methods: In total 187 strains were collected between 2008 and 2009. All strains were tested by Kirb-Bauer disk diffusion test for drug resistance. PCR and DNA sequencing were used to detected class I integrase gene and to clarify the context of gene cassette.

Results: Class I integrase gene was detected in 100 (53.4%) of the isolates analyzed. Seven different gene cassettes were identified, including a new integron (GenBank: HQ322622) carrying an unknown protein probably associated with recombination. The vast majority of the cassettes encoded amonoglycoside resistance gene, including aacA4, aadA1, aacC1, aac6 II , aadA2. Susceptibility data show that strains carrying class I integron were significantly more resistant to all of the antibiotics tested than isolates lacking class I integron. The correlation between the presence of integron and the multidrug-resistance of A. baumannii was statistically significant.

Conclusion: Drug resistance genes integrated by Class I integron were widespread in A. baumannii. Class I integron plays an important role in resistance of A. baumannii.