Kulkarni S V, Bala M, Bhattacharya J, Risbud A
Department of Microbiology and Clinical Pathology, National AIDS Research Institute, Bhosari, Pune, Maharastra, India.
Indian J Med Microbiol. 2015 Apr-Jun;33(2):277-81. doi: 10.4103/0255-0857.154878.
Emergence of multi-drug resistant Neisseria gonorrhoeae resulting from new genetic mutation is a serious threat in controlling gonorrhea. This study was undertaken to identify and characterise mutations in the mtrR genes in N.gonorrhoeae isolates resistant to six different antibiotics in the quinolone group.
The Minimum inhibitory concentrations (MIC) of five quinolones for 64 N.gonorrhoeae isolates isolated during Jan 2007-Jun 2009 were determined by E-test method. Mutations in MtrR loci were examined by deoxyribonucleic acid (DNA) sequencing.
The proportion of N.gonorrhoeae strains resistant to anti-microbials was 98.4% for norfloxacin and ofloxacin, 96.8% for enoxacin and ciprofloxacin, 95.3% for lomefloxacin. Thirty-one (48.4%) strains showed mutation (single/multiple) in mtrR gene. Ten different mutations were observed and Gly-45 → Asp, Tyr-105 → His being the most common observed mutation.
This is the first report from India on quinolone resistance mutations in MtrRCDE efflux system in N.gonorrhoeae. In conclusion, the high level of resistance to quinolone and single or multiple mutations in mtrR gene could limit the drug choices for gonorrhoea.
新基因突变导致的多重耐药淋病奈瑟菌的出现是控制淋病的严重威胁。本研究旨在鉴定和表征对喹诺酮类六种不同抗生素耐药的淋病奈瑟菌分离株中mtrR基因的突变。
采用E-test法测定2007年1月至2009年6月期间分离的64株淋病奈瑟菌对五种喹诺酮类药物的最低抑菌浓度（MIC）。通过脱氧核糖核酸（DNA）测序检测MtrR位点的突变。
淋病奈瑟菌菌株对诺氟沙星和氧氟沙星的耐药比例为98.4%，对依诺沙星和环丙沙星的耐药比例为96.8%，对洛美沙星的耐药比例为95.3%。31株（48.4%）菌株的mtrR基因出现突变（单/多）。观察到10种不同的突变，其中Gly-45→Asp、Tyr-105→His是最常见的突变。
这是印度关于淋病奈瑟菌MtrRCDE外排系统喹诺酮耐药突变的首次报道。总之，对喹诺酮的高耐药水平以及mtrR基因的单突变或多突变可能会限制淋病的药物选择。
