Study On The Bacterial Resistance And The Genetype Of Extended-spectrum β-lactamases In Gram-negative Bacilli

Objictive: To investigate the antibiotic resistance of gram-negative bacilli in hospital infections and the genetype of extended- spectrum β -lactamases producing stains in the 2nd hospital of LanZhou university.Metheds: Gram-negative bacilli form 2000 to 2004 were collected from hospital infection of the 2nd hospital of LanZhou university. The clinical isolates were identified and done susceptibility tests by the Microscan-4 and the Kirby-Bauer agar diffnsion method. The data were sorted and analyzed by whonet-5.3 software.The ESBLs-producing stains were confirmed by agar dilution test and the three-dimensional test. The gene type of ESBLs was confirmed by PCR.Result: 1. Gram-negative bacilli were collected from hospital infection of the 2nd hospital of Lan Zhou university.The first isolate was β.coli(34%).The rates of E.cloace and A.baumannii increase by year. The resistant rate of bacterials aganist antibiocitcs was higher and higher. The antibiocitc-resistance rate to the third generation cephalosporins of E.cloace and A.baumannii is 60-80%,40-70%. The isolates resistant to imipenem became more and more. A pandrug resistant acinetobacter baumannii was founed in our hospital.2. 49 ESBLs-producing stains were found from 175 strains which were collected from May 2005 to September 2005 in our hospital.The ESBLs-producingisolates include E.cloace, E.coli, Kpnenmoniae^ C.freundii^ P.aeruginosa and A.baumanniLg. The first two isolates were E.doace(YllA9), E.coli(15/49).The first three isolates of ESBLs-producing rate were E.cloace(56.6%)> E.coli(37.5%)and K.pnenmoniae(12.3%).The most ward of ESBLs-producing rate.is the neurology department.3.The ESBLs-producing rate of E.cloace, P.aeruginosa, A.baumannii is below 50%.By the Kirby-Bauer agar diffnsion test,the three-dimensional test should be used to detect the resistance phenotype of chinical strains of ESBLs.4.From May 2005 to Spetemper 2005,49 ESBLs-producing strains were isolated and confirmed by tests. They were positive in ￡ -lactamase test. Their drug resistant gene of plasmidic DNA were detected by PCR and the PCR products of TEM,SHV,and CTX-M-1 type were sequenced subsequently.The polyacylamide gel electrophones of their PCR products revealed that 34 stains harbored TEM type,5 strain SHV type.and using CTX-M-1 type specific primers,16 strain were positive.ll stains were negative.Conclusions :1.The resistant rate to most antibiotic of Gram negative rod is higher and higher by years in hospital acquired infection.2.The mostly ESBLs-producing isolates are E.cloace and ￡.co//.The department of neurology is the mostly ESBLs-producing bacterial ward.3.Three-dimensional extract test should were used to detect the resistance phenotype of E.cloace P.aeruginosa and A.baumannii by clinical microorganism lab.4.1n the 2nd hospital of LanZhou university,extended-spectrum P -lactamase producing gram-negtive bacial maily carried TEM and CTX-M resistant gene.