ABSTRACT
Objective To study the ability of standard strain and clinical isolates of Ureaplasma spp. to form biofilms in vitro and to compare the antibiotic susceptibility of sessile cells and their planktonic counterparts. Methods A total of 21 Ureaplasma wealyticum(Uu) isolates recovered from female patients diagnosed with cervicitis and Uu serovar 3 and Uu serovar 8( Uu3, Uu8) were included. Scanning electron microscope and confocal scanning laser microscopy were used to identify biofilm formation. Conventional antibiotic susceptibility tests and biofilm susceptibility assays for tetracycline, erythromycin and ciprofloxacin were carried out. The paired rank sum test and was applied to analyze the statistical differences between the MIC and the minimal biofilm inhibitory concentration. The x2 test was applied to analyze the statistical differences of global resistance percentages between planktonic cells and sessile cells. Results Uu3, Uu8 and 21 Uu isolates all can form biofilms in vitro. Minimal inhibitory concentration of sessile cells compared with planktonic cells were obviously higher for tetracycline, erythromycin and ciprofloxacin (P <0.001). Global resistance percentages between planktonic cells and sessile cells were different for erythromycin (9.52% vs 61.90% , P < 0. 001), ciprofloxacin ( 80. 95% vs 100% , P = 0. 035 ) and tetracycline (4. 76% vs 14.29% , P =0.293). Conclusion Uu isolates and Uu1, Uu8 all can form biofilms in vitro, and biofilm formation can strengthen resistance of Uu to antibiotics, even multidrug resistance was observed.
ABSTRACT
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.