The Resistance To β-lactam Antibiotics And Test Of ESBLs In Pseudomonas Aeruginosa Isolates

Objective To investigate the resistance to 5β-lactam antibiotics and to test ESBLs in Pseudomonas aeruginosa isolates from hospitals of AnHui province.To investigate the expression of ESBLs and their genotypes.At the same time,to investigate the molecular epidemiology of Pseudomonas aeruginosa which produce ESBLs.Methods Susceptibility of 218 Pseudomonas aeruginosa isolated from Anhui Province in 2005 to ceftriaxone,cefotaxime,cefiazidime,aztreonam,and piperacillin were tested by agar dilution method.Three-dimension test was used to detect ESBLs.PCR was used to investigate the genotypes of ESBLs from six Pseudomonas aeruginosa isolates identified by ceftriaxone three-dimention test.Totally,five genetypes of ESBLs were tested,which were SHV,TEM,CTX-M,PER,OXA.In addition, ERIC-PCR was used to detect the homology of Pseudomonas aeruginosa isolates from hospitals of AnHui province.Results The resistance rate of ceiftriaxone,cefotaxime,aztreonam,piperacillin,and ceftazidime were 59.2%,57.3%,56%,51.8%,and 39%,respectively.There was statistically significant difference between ceftazidime and aztreonam, ceftriaxone,cefotaxime,piperacillin(p＜0.01).the resistance rate of 73 isolates of Pseudomonas aeruginosa isolated from the city of Hefei was not drastically higher than that of Anhui Province(p＞0.05).43 Pseudomonas aeruginosa isolates were found producingβ-lactamase.Among these isolates,4 were considered produing ESBLs,2 producing ESBLs and AmpCβ-lactamases.Among the six Pseudomonas aeruginosa isolates identified by ceftriaxone three-dimention test to produce ESBLs,one carried PER-1-type-ESBLs,one carried OXA-10-type-ESBLs,two carried TEM -1-type-BLA.The last two didn't belong to the five genotypes above. ERIC-PCR suggested that these strains were accordingly classified into 6 different genotypes,so there are no identical strains.Conclusions Ceftazidime was the most susceptible antibiotic to Pseudomonas aeruginosa isolates in 5β-lactams tested.There were 6 Pseudomonas aeruginosa isolates,which producted ESBLs.The rate was 2.7%. PER-1,OXA-10 were included in the genotypes of ESBLs carried by Pseudomonas aeruginosa in AnHui province.ERIC-PCR proved that the 6 strains' genotypes were different from each other.