The Possession Of ExoS, ExoU By The Clinical Strains Of Pseudomonas Aeruginosa And Their Effect To Prognosis Of Pneumonia

Objective:Pseudomonas aeruginosa is one of important pathogenic Gram's negtive bacteria in the clinic.There are more chronic patients and more motality in severe infection,which become one of tangle in the treatment.The discovery of type three secretion sysytem was a impressive progress in the research on bacterial pathogenesis.This study focus on the possession of exoS, exoU in the clinical isolates and their effect to the prognosis of Pseudomonas aeruginosa pneumonia, the effect of Azithromycin and Lysine acetylsalicylate on the tanscription of exoS, exoU,which developed insights in bacterial pathogenesis and the strategy of anti infection,gave a hand on the selection of medicine.Methods:1. Strains, Susceptibility testing:A total of 43 strains of Pseudomonas aeruginosa were isolated from a hospital in Tianjin from Jan.2007 to March 2008, including 31 isolates from sputum,5 isolates from urine,4 isolates from and 5 isolates from blood. Antibiotic susceptibility was tested by K-B method.The antibiotic are Ceftazidime,Ceftriaxone,Piperacillin,Cefoperazone/sulbactam,meropenem,Amik-acin,Cefepime,Levofloxacin,Ciprofloxacin.2. Detect the virulent gene exoS and exoU by polymerase chain reaction in the clinical isolates of Pseudomonas aeruginosa,divide the isolates into two groups based on the virulent gene,compare their resistance.3. Select 20 cases of Pseudomonas aeruginosa pneumonia from the infectious department of a Tianjin hospital from June 2008 to March 2009,20 strains of Pseudomonas aeruginosa from the sputum of patients,divede them into two groups based on the virulent gene,compare the difference in prognosis of two groups by prospective cohort study4. Detect the effect of Azithromycin and Lysine acetyl salicylate to the mRNA expression of exoS,exoU by reverse transcription polymerase chain reactionResults:1. Each of Pseudomonas aeruginosa isolate contained either the exoS gene or exoU gene, exoS was harbored by 37 of 43 examined isolates, exoU was harbored by 6 of 43 examined isolates.2. Compared with exoS(+) isolates, exoU(+) isolates were more likely to be drug-resistant,and there were significant diference in ceftazidime, levofloxacin, ciprofloxacin3. ExoS was harbored by 17 of 20 examined isolates, the mean hospital day 17+ 5,four of them (23.5%) cultured from patients with Severe Pneumonia, exoU was harbored by 3 of 20 examined isolates,the mean hospital day 36+12, all of these 3 isolates(100%) were cultured from patients with Severe Pneumonia.4. After culure in Azithromycin,the relative value of gray-scale of exoS turned to higher than the control,got to the highest in the 2μg/ml group,and gradually descend to the level of the control as the concentration of Azithromycin increased. After cultured in Azithromycin,the relative value of gray-scale of exoU decreased obviously than the control.5. After cultured in different concentrations of Lysine acetylsalicylate,the relative value of gray scale of exoS got little change,the relative value of gray scale of exoU got little change.Conclusions:1. The percentage of isolates with exoU is lowwer in the clinical isolates of Pseudomonas aeruginosa,but the resisitance of them is higher.2. The percentage of isolates with exoU is lowwer in the clinical isolates of Pseudomonas aeruginosa Pneumonia, but the patients infected by exoU(+) isolates were associated with worse clinical outcomes, and exoU(+) isolates appeared highly pathogenic3. In vivo, the bacterial experiment revealed, Azithromycin promote the mRNA expression of exoS, got to the highest in the 2μg/ml group,and gradually descend to the level of the control as the concentration of Azithromycin increased. Azithromycin suppress the mRNA expression of exoU4. In vivo, Lysine acetylsalicylate didn't show any effect to the mRNA expression of exoS,exoU.