Study of the role of integrons in drug resistance of clinical isolates of Acinetobacter baumannii

Objectives To investigate the distribution of class I integrons and class Ⅱ integrons in Acinetobacter baumanniiisolated from clinical specimens and to study the relationship between integrons and drug resistance of A.baumannii.Methods In total,70 strains of A.baumannii were randomly collected from the Second Xiangya Hospital from September 2008 to September 2009.The disk diffusion method(Kirby-Bauer) was used to determinate their sensitivity to 15 antibacterials.Class I and class Ⅱ integrons were also identified using a polymerase chain reaction(PCR).Results Antimicrobial susceptibility tests showed that A.baumannii was least resistant(15.71%) to Cefoperazone/sulbactam(SCF) and most resistant(72.86%) to Aztreonam(ATM).PCR detected class I integrons at a rate of 57.14%(40/70) and class Ⅱ integrons at a rate of 7.14%(5/70).Compared to isolates negative for class I integrons,positive isolates had significant resistance to all tested antibiotics except for SCF(χ2=1.47,P=0.23),with a rate of resistance ranging from 55.00% to 82.50%.Differences in the rate of resistance to 12 antibacterials were statistically significant(P0.01),though the same was not true for imipenem and meropenem.Conclusion A.baumannii mainly carries class 1integrons,and there is a close relationship between class 1 integrons and multidrug resistance of A.baumannii.