Identification of genes related to induced resistance to ceftriaxone in Neisseria gonorrhoeae using suppression subtractive hybridization and DNA microarray

Objective To elucidate the molecular basis for induced resistance of N. gonorrhoeae to ceftriaxone in vitro. Methods The reference strain ATCC49226 and clinical isolate ZSSY00205 of N. gon-orrhoeae were exposed to subinhibitory concentration of ceftriaxone for the induction of resistance. Then,suppression subtractive hybridization was performed with the pre-induction parent strains as drivers and post-induction mutant strains as testers to create a subtractive cDNA library. Following that, a total of 192 clones were randomly selected from the library, and arrayed by spotting onto nylon membranes. Finally, dif-ferentially expressed genes were screened by hybridization with labeled-RsaI restriction fragments from the sensitive and resistant N.gonorrhoeae strains respectively, and analyzed by sequencing and homology research using Blast program. Results A subtractive library for these resistant N.gonorrhoeae strains was generated by SSH technique. Microarray analysis and homology research confirmed 5 genes related to ceftriaxone resistance, i.e. mtrR, mtrC, gyrB, rpsJ and PJD1. Conclusions The induced resistance of N. gonorrhoeae to ceftriaxone may be associated with mtrR, mtrC, gyrB, rpsJ and PJD1 genes which probably mediate the resistance by enhancing the activity of efflux pump system. Key words: Neisseria gonorrhoeae;  Ceftriaxone;  Drug resistance;  Suppression subtractive hybridization;  Oligonucleotide array sequence analysis