Pranabika Singha, Debadatta Dhar (Chanda, Anand Prakash Maurya, Atanu Chakravarty and Amitabha Bhattacharjee
Class 1 integron continues to be one of the major factors responsible for multidrug resistance in Enterobacteriaceae family. The diversity of integron cassette array with special reference to trimethoprim and sulfomethoxazole resistance determinants often compromise treatment regime. The present works investigate class 1 integron and carriage of trimethoprim resistant marker as gene cassette. Out of 268 consecutive, non-duplicate clinical isolates of Enterobacteriaceae resistance pattern against 5 antimicrobial agents assessed by disk diffusion and minimum inhibition concentration. The presence of integron was done by PCR targeting integrase gene (intI1 and intI2). Whole gene mapping was done by amplifying 5´-CS and 3´-CS region of class I integron. The amplified gene cassette was cloned and antibiogram of clone was assessed.The isolates showed significantly high amount of resistant against co-trimoxazole (89%). The carriage of class I integron was found detected in 187 isolates. Five different cassette arrangements were detected: (dfrA17-aadA5), (dfrA30-aadA5), (dfrA12-orfF-aadA2), (dfrA1-aadA1) and (aacA7-aadA6-qacEΔ1-sul-orf5) with complete 3´-Conserved segments. The most prevalent cassette combination was (dfrA17-aadA5). This study was identified a set of gene cassette carrying dfrA30 gene with aadA5 aminoglycoside resistance gene. Further investigation is required to determine the prevalence of different dfr variants among Enterobacteriaceae and their contribution in hospital environment.
