Prevalence of integrons and analysis of resistance genes in integrons among Acinetobacter baumannii isolates from Nanjing region / 中国感染与化疗杂志

ABSTRACT

Objective To investigate the prevalence of integrons in A.baumannii isolates,analyze the correlation between inte- grons and resistance of A.baumannii,and study the resistance genes in integrons.Methods A total of 106 strains of A.bau- mannii were collected to test the antibiotic susceptibility by disk diffusion method.The classification of integrons was per- formed by analyzing the positive PCR products using restriction fragment length polymorphism (RFLP).The variable region of integrons was amplified by integron PCR.RFLP and DNA sequencing were used to analyze the resistance genes in integrons. Results About 52.8% (56/106) of the isolates showed integron positive.PCR-RFLP analysis revealed that they were all class I integrons.About 94.6%(53/56) of the positive strains with integrons owned the variable region,which was confirmed by integron PCR.The sizes of the amplicons ranged from 0.15 kb to 2.8 kb.All together 7 different cassette arrays were detec- ted,including genes coding resistance to aminoglycosides (aadA1,aadA2,aadA5,aadB,aacA4),sulphonamides (dfrⅫ, dfr17),?-lactam compounds (bla_(ara-10)),chloramphenicol (catB-like,catB8),and two open reading frames (orfF,orfI) with unknown function.A novel cassette array orfI-aadA1 was reported,and its GenBank accession number was DQ092497.Conclu- sions Class I integrons are widespread in A.baumannii isolates in Nanjing.The integrons are closely associated with the resist- ance and multidrug resistance in A.baumannii isolates.