Objective To study the relationship between the expression of mtrF gene and high-level multiple resistant Neisseria gonorrhoea.Methods ① The susceptibility of 58 clinical Neisseria gonorrhoeae to 5 kinds of antibiotic agents was tested by disc diffusion method.② The minimum inhibitory concentration(MIC) of erythromycin was determined by tube dilution method.③ The expression of mtrD and mtrF gene in susceptive group,inter-mediated resistant group and high-level multiple resistant group was detected by semi-quantitative RT-PCR.Results ① There were 30 strains presenting resistance to two or more than two antimicrobial agents,which accounted for 51.7% of the 58 clinical strains.② The number of strains sensitive,intermediate and resistant to erythromycin was 7,21 and 30,respectively,and there were 17 strains with erythromycin MIC≥32.0 ?g /mL.③ Compared with that in susceptive group and inter-mediated resistant group,mtrF expression was up-regulated in high-level multiple resistant group(P

Objective To investigate the impact of functional enhancement of efflux pump system and reduced permeability of outer membrane on high-level multiple resistant Neisseria gonorrhoeae.Methods Several high-level multiple resistant isolates with erythromycin MIC=128.0 mg/L,accompanied by concurrent resistance to several antimicrobial agents,were selected.13 bp inverted sequence positioned within the mtrR promoter region were amplified by PCR and directly sequenced to detect the possible gene change.The outer membrane proteins of the strains were extracted to analyze the constitutive profiles by SDS-PAGE.Results There were no gene mutations in 5 sensitive strains.All the 3 high-level multiple resistant strains contained the same mutation and exhibited a single A/T base pair deletion in 13 bp inverted sequence positioned within the mtrR promoter region.Meanwhile porin protein 31 ku deficiency was found in all the 3 resistant strains.Conclusion The functional enhancement of efflux pump system induced by a single A/T base pair deletion in 13 bp inverted sequence positioned within the mtrR promoter region and the decreased cell envelope permeability induced by the absence of porin protein may have some effect on mediating high-level multiple resistance in Neisseria gonorrhoeae.

ObjectiveToevaluatethecorrelationbetweenfluoroquinoloneresistanceinNeisseriagonor-rhoeaeandmutationsingyrAandparCgenes.Methods①Thesusceptibilities58clinicalisolatesofN.gonorrhoeaeto5fluoroquinolonesweretestedbydiscdiffusionmethod.②Theminimuminhibitoryconcentration(MIC)ofciprofloxacinwasdeterminedbyE-test.③Thefragmentsincludingthequinoloneresistance-determiningregion(QRDR)wereamplifiedbyPCRingyrAgeneof18strains,andparCgeneof8strains,andtheirrelativefragmentsweredirectlysequenced.Results①Thenumbersofstrainssimultaneouslysensitive,intermediateandresistanttociprofloxacin,ofloxacin,lomefloxacin,fleroxacinandenoxacinwere2,4and39,respectively.②TherangeofciprofloxacinMICwas0.004～12.0?g/mLin58strains.Thenumbersofstrainssensitive,intermediateandresistanttociprofloracinwere2,17and39,respectively.③ThestrainswithciprofloxacinMICfrom0.004～0.016?g/mLhadnomutationingyrAandparCgenes.ThestrainswithMICfrom0.064to0.094?g/mLcarriedasinglepointmutationingyrAgene,whilethestrainswithMIC≥0.25?g/mLcontainedtwomutationsingyrAgene.Inaddition,thestrainswithMIC≤0.25?g/mLhadnomutationinparCgeneandthestrainswithMIC≥1.0?g/mLexhibitedasinglepointmutationinparCgeneandtwomutationsingyrAgene.④Of16strainscontainingmutationingyrAgene,15strainsexhibitedsubstitutionofSer91(TCC)→Phe(TTC).Conclusions①MutationswithingyrAgenemediatelowandmoderatelevelsfluoroquinoloneresistancewhilemutationswithinparCgeneparticipateinhighlevelfluoro-quinoloneresistanceinN.gonorrhoeae.②SubstitutionofSer91→PheingyrAgeneisthepivotalmutationresultinginfluoroquinoloneresistanceinN.gonorrhoeae.