Study On Clinical Characteristics And Pathogenic Mechanism Of Pseudomonas Aeruginosa Isolated From Diabetic Foot Infections

Objective:1.To determine the clinical characteristics of diabetic foot ulcer(DFU)with multi-drug resistant Pseudomonas aeruginosa(MDRPA)as well as the influence of MRPA to the prognosis of DFU.2.To analyze pathogenic genes?the relationship between pathogenic genes and MDRPA?the effect of pathogenic genes on the DFU and homology of the MDRPA stains isolated from DFU,compared with the Pseudomonas aeruginosa(PA)isolated from sputum of ICU patients.Methods:1.117 diabetic foot patients who infected by PA hospitalized between Sep.2008 and Sep.2012 in Tianjin Metabolic Diseases Hospital were included in this study.The clinical features of patients were summarized.Risk factors of diabetic foot infected by MDRPA were analyzed by multi-factor logistic analysis among the groups of patients with non-multidrug and multidrug-resistant PA infection;Resistant characteristics among MDRPA and non-MDRPA were analysis based on the results of antimicrobial susceptibility;Relationships between the MDRPA isolates and the degree of diabetic foot infection(DFI)and the effect of MDRPA on the DFU were analyzed.2.The DNAs of those PA isolates which separated from patients who had DFU and hospitalized in Tianjin Metabolic Diseases Hospital between Sep.2012 and Sep.2013.Five major virulence factors of TTSS were detected by polymerase chain reaction(PCR).To analysis the distribution of virulence factors compared with PA isolates separated from of ICU of Tianjin Third Central Hospital.To explore the relationship between the major virulence factors exoU?exoS of TTSS with MDRPA and their effect on DFU.RAPD technique was used to detect the homology of PA isolates from Tianjin Metabolic Diseases Hospital and Tianjin Third Central Hospital.Results:1.The detection rate of MDRPA from PA which isolated from DFU was relatively high(36.8%),frequency of hospitalization,previous duration of antibiotic therapy and osteomyelitis were risk factors for diabetic foot infected by MDRPA.2.Compared with non-MDRPA group,severe infection of MDRPA hold larger proportion(60.5%vs39.2%),slightly infection of MDRPA hold smaller proportion(9.3%vs29.7%),there were significant differences between the two groups(P =0.018)· The proportion of Wagner 3.4 of MDRPA group was higher than non-MDRPA group(72.1%vs63.5%).Compared with non-MDRPA group,the patients of MDRPA group had severe illness status,most of them complicated with osteomyelitis,abscesses,gangrene.3.The resistance rate of PA of MDRPA group and the group of non-MDRPA to third generation cephalosporin was 37.8%?55.8%?fourth generation cephalosporin was as high as 30.2%;the resistance rate to piperacillin was 44.2%,but the resistance rate to piperacillin/tazobactam was low(8.1%to14.0%);Only two PA isolates of 117 PA isolates were resistant to imipenem,resistance rate was 1.7%;resistance rate to amikacin was lower(8.1%to 11.6%);resistance rate to ciprofloxacin and levofloxacin were 30.0%?58.1%;PAhad highest resistance rate to gentamicin,up to 65.1%.4.Compared with non-MDRPA group,MDRPA had high amputation/toe rate(32.6%vsl6.2%),low cure rate(20.9%vs41.9%),there were significant differences between the two group(P = 0.032).5.More than 85%of the PA strains had the following two genotypes:I type:exoU +/exoS-/pcrV +/exoT +/exoY + or Type II:exoU-/exoS +/pcrV +/exoT +/exoY +.Analysis of all five genotypes also indicated that the exoU and exoS genes were mutually exclusive in the isolates tested.The pcrV gene was present in each isolate;while the exoT and exoY genes were present in most of the PA isolates.The distribution of exoU and exoS gene in MDRPA and non-MDRPA had no significant difference.6.Patients with diabetic foot infected by PA which carried exoU gene had lower cure rate than patients infected with PA which carried exoS gene,and higher amputation/toe rate than patients infected with PA which carried exoS gene,there was significant difference between the two groups(25.0%vs65.2%,33.3%vs8.7%;P<0.05).7.As RAPD fingerprinting showed,three PA isolates came from two hospitals were classified as a type A clone strains,five PA isolates came from two hospitals were classified as a type B clone strains;2 MDRPA isolates of Diabetic Foot Department were classified as a type C clone strains,3 MDRPA isolates of ICU Department were classified as a type C clone strains.PA isolates of type B clones were MDRPA and carried exoU gene,2 came from Diabetic Foot Department and 3 came from ICU Department,they were virulent epidemic strain of two hospitals.Conclusion:The detection rate of MDRPA from PA which isolated from diabetic foot was relatively high(36.8%),MDRPA often existed in the ischemic wounds,severe infection and deeper wounds,frequency of hospitalization,previous duration of antibiotic therapy and osteomyelitis were risk factors for diabetic foot infected by MDRPA.PA had shown quite high resistance rates to cephalosporins,quinolones,but Drug sensitivity of PA to the imipenem,enzyme inhibitor complexes and amikacin was fairly high.MDRPA infection of DFU often lead to a poor prognosis,MDRPA increased risk of amputation/toe.PCR results showed that PA carried the toxin gene exoU shared lower proportion,but its virulent was high and it often lead to high amputation/toe rate and poor prognosis.Most of MDRPA carried exoU gene,MDRPA and exoU gene were closely related.Consider MDRPA interacted with exoU lead to poor clinical prognosis.B type of MDRPA of PA isolates from two tertiary hospitals in Tianjin Sep.2012-Sep.2013 might was a major epidemic strain of the region MDRPA in the meantime.