Antibiotic Resistance Situation Of Pseudomonas Aeruginosa Clinical Isolation Strains And Studies Of Biofilm Initiation And Virulences Of Pseudomonas Aeruginosa Clinical Isolation

ANTIBIOTIC RESISTANCE SITUATION OF PSEUDOMONASAERUGINOSA ISOLATED FROM CHILDREN IN CHONGQINGDURING2011-2013.Methods: A total of2508clinical strains of PA isolates fromChildren’s Hospital of Chongqing Medical University were retrospectiveanalyzed. Isolation rate, clinical department distribution, Specimen Sourceand antibiotic resistance history over years were all analyzed.Results: A total of2508clinical PA strains was isolated During2009-2013. Isolation rates of PA were3.33%～4.56%. Most PA strainswere isolated from pneumology department, making up20.08%of allstrains. Most strains were isolated from Sputum, making up66.38%of allstrains. During these5years, insensitivity of PA to piperacillin/tazobactam,imipenem, meropenem, and ceftazidime were high. insensitivity of PAisolated from pediatric intensive care unit (PICU) to most antibacterial drugs were apparently higher than other departments of our hospital.Conclusion: From2009to2013, isolation rate of PA in our hospitalrose year by year. Most PA strains were isolated from pneumologydepartment, PICU and neonatology department, and so rational usingantibiotics should be valued in these departments. Antibiotic resistantsituation was particularly serious. STUDY OF BIOFILM INITIATION AND VIRULENCE OFDIFFERENT PSEUDOMONAS AERUGINOSA CLINICALISOLATION STRAINSObjective: to study distinctions among Pseudomonas aeruginosa (PA)clinical strains with different abilities of BF initiation.Methods: crystal violet staining was used to measure biofilmsformation of PA clinical strains.BCA Protein Assay was used to measureprotein concentrations of PA clinical strains’ supernants. Elastin-Congo red(ECR) powder was used to test LasB activity.Pyocyanin (PCN) was testedby chloroform extraction.LB plates were used to measure swimmingmobility and twitching mobility.Polymerase chain reaction was used todetect lasR, lasI, lasB, rhlR, rhlI and rhlAB genes in PA clinical strains.lasR,lasI, rhlR and rhlI genes were sequenced and their sequences werecompared with PAO1.Results:12PA clinical strains were classified into2groups by biofilminitiation abilities.One was BF++group, and the other was BF+group. Theabsorbance on470nm wavelength of the biofilm formed by these twogroups of PA after crystal violet staining were12.075±2.453and1.614±0.133respectively. There was no significant difference between twostrain groups’supernants protein concentrations. The absorbance on495nmwavelength of ECR supernant of two strain groups were0.290±0.140and 0.065±0.049respectively. The absorbance on520nm wavelength of PCNHydrochloric Acid Solution were0.192±0.696and0.153±0.036.Swimmingdiameters of two strain groups were12.55±4.60mm and6.44±1.27mm.Twitching diameters of two strain groups were12.55±4.60mm and6.44±1.27mm. All these PA clinical strains carried lasR, lasI, lasB, rhlR,rhlI and rhlAB genes. The RhlI amino acid sequences were compared withPAO1and identities between12PA clinical strains and PAO1were allhigher than96.43%. There were20amino acids missing in bj8’s RhlR.Conclusion: PA clinical strains with strong ability of biofilm initiationhad high LasB activity and twitching mobility. There was genetic mutationsin bj8’s genome.