The Research On Drug-resistance, Genotype And Related Diseases Of Extended Spectrum-lactamases Escherichia Coli

ObjectiveTo study the isolation rates of Escherichia coli (E.coli), the detection rates of extended spectrumβ-lactamases (ESBLs) E.coli, and the epidemic condition of CTX-M-type gene of Dali.Methods1. Bacteria strains:213 E.coli strains were collected from the Microbiology Laboratory of the Affiliated Hospital of Dali University, Dali prefecture Hospital and the NO.l Hospital of Dali City. All tested strains were identified by the automated microbial identification system (VITEK-2 Compact). E.coli stains were preserved in 1.5ml EP tubes which contained sheep blood and were stored at-70℃.2. Detection of ESBLs production:All tested E.coli were detected by the K.-B method of phenotypic confirmatory test which recommended by the CLSI. Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 700603 were used as quality control organisms according to CLSI guidelines.3. Antimicrobial susceptibility test:The antimicrobial susceptibility tests were conducted to all of the E.coli isolates producing CTX-M. The MICs of 10 antibiotics were determined. The drug-resistance of each strain was analyzed.4. PCR amplification and molecular analysis. The plasmids of all ESBL-producing isolates were abstracted and subjected to the PCR amplification. The PCR products were analyzed using electrophoresis. Then the PCR products of 10 CTX-M-positive strains were submitted to sequence. Finally, the standard BLAST database files were applied to analyze the sequence results.5. Infective diseases:Refer to the medical records, the clinical distribution of ESBLs E.coli and its connection with infectious diseases were retrospectively analyzed.Results1. A total of 213 Escherichia coli isolates were collected, from three general hospitals in Dali, including 89 from the Hospital of A,54 from the Hospital of B,70 from the Hospital of C.2. Of 94 ESBLs-positive E.coli,71 strains were CTX-M-producing E.coli.30 strains (31.9%) were confirmed to carry CTX-M1 gene and 45 strains (47.9%) harbouring CTX-M9 gene. Four strains (4.3%) were carrying both CTX-M1 gene and CTX-M9 gene.3. Of 213 E.coli isolates,94 strains were confirmed producing ESBLs, shared the positive rate of 44.1%. The drug-resistance of ESBLs-positive strains was higher than that of ESBLs-negative strains. All ESBLs-positive E.coli were multidrug resistant strains. All the ESBLs-producing strains were susceptible to Imipenem. These strains showed higher resistant to other antibiotics:Ampicillin, Aztreonam, Cefoxitin, Cefepime. Ciprofloxacin and Cefotaxime. ESBLs-producing E.coli showed lower drug resistant rates to Ceftazidime, Amikacin and Piperacillin/Tazobactam.4. Refer to medical records, the bacteria were mostly isolated from sputum and urine and lead to infective diseases of respiratory system and urinary system.Conclusions1. E.coli is the normal microflora in intestines. All tested strains were isolated from sputum and urine, which illustrated that E.coli could cause translocation induced abenteric infection.2. The drug resistance of CTX-M-type ESBLs E.coli was serious. All of the ESBLs-producing E.coli strains were susceptible to Imipenen, but they showed different resistance to other antibiotics.3. The detection rate of CTX-M-type ESBLs in E.coli isolates from Dali region was 44.1%.4. Both CTX-M1 gene and CTX-M9 gene were found among three hospitals. Moreover, four strains were confirmed harbouring two types CTX-M genes above.