Study On Isolating Culture And Antimicrobial Susceptibility Of Chlamydia Trachomatis Clinical Strains

Chlamydia trachomatis is one of the most common pathogen of venereal disease home and abroad.Urogenital chlamydial infection is one of the most prevalent STIs worldwide.Ct also causes many complications and serious mental stress to the patients.According to the estimation of WHO,there are 93 million new cases every year and making severe economic burden to the society.Antimicrobials are the main drugs for the treatment of Ct infection.It is thought that the microbiological cure rate of antimicrobials was high.However,clinical treatment failure has been increasingly reported.There are many reasons for the failure,age of patients and renewal of sexual intercourse during the treatment,the low compliance,drug bioavailability can associate with the failure.And most of all,the clinic drug resistant strains usually induce treatment failure;even forming persistent infection.As the antimicrobials alternation and rational use strengthened,the antimicrobial susceptibility of Ct is changing.Objective To investigate the in vitro effects of various antimicrobials against the clinic isolates of Ct,which are now usually used in clinic.To understand the susceptibility of Ct in our clinic,moreover to explore diversify of the susceptibility of Ct and the relation between the clinic curative effects and the experimental results.To reserve the clinical strains and it will lay a foundation for further research.Methods Collected 148 urethral or cervix swabs from the patients who came to Tianjin sexually transmitted disease institute from March 2006 to March 2008.All of the patients fit to the collection standards and we recorded their clinical data.We undertook cell culture of clinical samples with McCoy cell on the foundation of Ct E standard strain.All the clinical strains had been blind-passaged.The positive strains of the fifth generation were kept on culturing.When above 90%inclusions formed, we amplified this strain and reserved in refrigerator of -80℃.First,we explore the experimental conditions of the antimicrobial susceptibility of Ct with Ct E standard strain.Then decide the inoculum size of the Ct,which can cause cell infection rate beyond 90%.Then we did the antimicrobial susceptibility test with 96-well plate. Minimal inhibitory concentration(MIC) was determined as the lowest concentration under which there was no inclusion forming.Results There were 38 positive clinical samples and 32 samples infection rate beyond 90%.MICs of the 32 Ct clinical ranges were as follows(μg/ml): erythromycin:0.25～2;clarithromycin:0.004～0.032;azithromycin:0.25～1;tetracycline: 0.079～0.625;doxycycline:0.016～0.125;minocycline,0.008～0.064;levofloxacin:0.125～1;sparfloxacin:0.016～0.128;moxifloxacin:0.03～0.24;rifamyin:0.008～0.03.The results dedicated that 6 wild-type were resistant to erythromycin.Conclusions 1,Centrifugation and blind passage can improve positive rate of clinical strains of Ct.2,We found that six wild isolates of Ct were resistant to erythromycin.It reflected that there may be clinical wild isolates of Ct resistant to erythromycin in Tianjin.3,There was difference between the clinic curative effect and the experimental result.4,Reserved the positive clinical strains and laid a foundation for further research.