Surveillance Of Antimicrobial Susceptibilities Of The Nesseria Gonorrhoeae And The Immune Regulation Involvement Of The Indoleamine 2,3-Dioxygenase-1

Chapter one:Surveillance of antimicrobial susceptibilities of the Nesseria gonorrhoeae in NanjingObjective:The aim of this study was to:update antimicrobial susceptibility data of Neisseria gonorrhoeae recently isolated in Nanjing, China and identify specific determinants of antimicrobial resistance and genotypes of isolates with decreased sensitivity to ceftriaxone.Methods:334 N. gonorrhoeae isolates were collected consecutively from symptomatic men attending the Nanjing STD Clinic between April 2011 and December 2012. The minimum inhibitory concentrations (MICs) for penicillin, tetracycline, ciprofloxacin, spectinomycin and ceftriaxone were determined by agar plate dilution for each isolate. Penicillinase-producing N. gonorrhoeae (PPNG) and tetracycline-resistant N. gonorrhoeae (TRNG) were examined and typed for β-lactamase and tetM encoding plasmids respectively. Isolates that displayed elevated MICs to ceftriaxone (MIC≥0.125 mg/L) were also tested for mutations in penA, mtrR, porBlb, ponA and pilQ genes and characterized by N. gonorrhoeae multi-antigen sequence typing (NG-MAST).Results:98.8%(330/334) of N. gonorrhoeae isolates were resistant to ciprofloxacin; 97.9%(327/334) to tetracycline and 67.7%(226/334) to penicillin. All isolates were susceptible to ceftriaxone (MIC≤0.25 mg/L) and spectinomycin (MIC≤32 mg/L). Plasmid mediated resistance was exhibited by 175/334 (52%) of isolates:120/334 (36%) of isolates were PPNG and 104/334 (31%) were TRNG. 90.0%(108/120) of PPNG isolates carried the Asia type (3-lactamase encoding plasmid and 96%(100/104) of TRNG isolates carried the Dutch type tetM containing plasmid. Elevated MICs for ceftriaxone were present in 15 (4.5%) isolates; multiple mutations were found in penA, mtrR, porBlb and ponA genes. The 15 isolates were distributed into diverse NG-MAST sequence types; four different non-mosaic penA alleles were identified, including one new type.Conclusions:N. gonorrhoeae isolates in Nanjing generally retained similar antimicrobial resistance patterns to isolates obtained five years ago. Fluctuations in resistance plasmid profiles imply that genetic exchange among gonococcal strains is ongoing and is frequent. Ceftriaxone and spectinomycin remain treatments of choice of gonorrhea in Nanjing, however, decreased susceptibility to ceftriaxone and rising MICs for spectinomycin of N. gonorrhoeae isolates underscore the importance of maintaining surveillance for AMR (both phenotypic and genotypic).Chapter two:The immune regulation of the Neisseria gonorrhoeae involved indoleamine 2,3-dioxygenase-1Objective:This study plans to prove the role of the immune regulation of the indoleamine 2,3-dioxygenase-1 in N. gonorrhoeae infection.Methods:We firstly detected the expression and the activity of the indoleamine 2,3-dioxygenase-1(IDO-1) in the human monocyte-derived dendritic cells(moDC) infected with N. gonorrhoeae; Then we tested the effect of the IDO-1 inhibitor, L-1-MT, on the proliferation of the T cells stimulated by the N.gonorrhoeae treated moDC; Finally, neutralizing antibodies against the IFN-y and the TLR4 were added to the coculture system of the N.gonorrhoeae and the moDC, separately, to determined the involvement of the IFN-y or TLR4 in the induction of the active IDO-1.Results:N.gonorrhoeae could induce the active IDO-1 in human moDC, and L-1-MT can enhance the proliferation of the T cells stimulated by the N.gonorrhoeae treated moDC. The induction of IDO-1 by N.gonorrhoeae does not depend on the viability of the bacterial cells, but partially mediates by TLR4 and partially depends on the production of IFN-γ.Conclusions:N.gonorrhoeae induces the production of IDO-1 in human moDC to down-regulate the T cell proliferation, which could be one of the immune regulation mechanisms of the N.gonorrhoeae.