China Animal Husbandry and Veterinary Medicine ›› 2023, Vol. 50 ›› Issue (10): 4231-4242.doi: 10.16431/j.cnki.1671-7236.2023.10.037

• Basic Veterinary Medicine • Previous Articles     Next Articles

Isolation,Identification and Molecular Characteristics of Drug Resistance and Quinolone Resistance Genes in Escherichia coli from Nipponia nippon

ZHANG Hui1, SHAO Lele1, YANG Yongchun1, JI Yi1, MA Wulin1, ZHAI Yimeng1, BAI Hongqing3, ZHOU Yingshan1, LEI Lei1, ZHENG Yadong1, SONG Houhui1, QIU Guoqiang2   

  1. 1. Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Zhejiang International Science and Technology Cooperation Base for Veterinary Medicine and Health Management, China-Australia Joint Laboratory for Animal Health Big Data Analytics, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang Agriculture and Forestry University, Hangzhou 311300, China;
    2. Deqing County Ecological Forestry Comprehensive Service Center, Deqing 313200, China;
    3. Deqing Natural Resources and Planning Bureau, Deqing 313200, China
  • Received:2023-03-23 Online:2023-10-05 Published:2023-09-26

Abstract: 【Objective】 The experiment was aimed to master the drug resistance,resistance genes,and molecular characteristics of Escherichia coli (E.coli) in domesticated Nipponia nippon in Deqing county,Zhejiang province,and provide basic data for the treatment of E.coli infection in Nipponia nippon.【Method】 Fresh feces of Nipponia nippon were collected and E.coli isolates were identified by using bacteria isolation and culture,biochemical characteristics and 16S rDNA sequencing. Then the broth dilution method was used to detect the minimum inhibitory concentration (MIC) of seven kinds of antimicrobial agents,including ciprofloxacin,gentamicin,amikacin and so on,against E.coli isolates from different Nipponia nippon. Nine quinolone resistance genes such as qnrS1,gyrA, gyrB and so on of the respective strains were identified by PCR and sequencing,and the relationship between the mutation of the amino acid and drug resistance was analyzed.The horizontal transfer of plasmids carrying resistance genes were detected by conjugation experiments,and drug resistance were determined.The association between host’s age,drug resistance-genes and drug resistance were analyzed by using Chi-square test and Fisher exact test.【Result】 A total of 98 Nipponia nippon feces were collected and all were isolated and identified with E.coli strains.Of which,98 isolates from different captive Nipponia nippon were highly resistant to quinolone ciprofloxacin (65.3%,64/98),and highly sensitive to the remaining 6 drugs (sensitivity rates were above 90%).The age of Nipponia nippon was highly significantly correlated with ciprofloxacin resistance (P<0.01).Thirty-one E.coli strains isolated in this study were selected for resistance genes detection.The prevalence of mutations in the quinolone resistant genes marR,gyrA,parC,and gyrB in 31 selected isolates ranged from 3.2% to 80.6%,and the proportion of strains carrying the plasmid resistant gene qnrS1 was 22.6% (7/31).The isolates carrying one or more resistance genes accounted for 93.5% (29/31),and were distributed in six drug resistance genotypes,including 10 strains of marR/gyrA/parC genes,6 strains of marR/qnrS1 genes,6 strains of marR gene,3 strains of gyrA/parC genes, 3 strains of marR/gyrA genes,and 1 strain of marR/gyrB/qnrS1 genes.The ciprofloxacin resistance phenotype was significantly correlated with drug resistance genotype (P=0.026). Both monogenic and combined mutations of the gyrA and parC genes were related to quinolone resistance (P=0.038).The conjugation experiment results showed that the transfer success rate of the qnrS1 resistance gene carried by the E.coli isolates in this study was 28.6% (2/7) in one conjugation event,which could lead to an increase in quinolone resistance in the recipient bacteria.【Conclusion】 This study identified the antibiotic resistance of E.coli from Nipponia nippon,and identified that the main cause of quinolone resistance in Nipponia nippon was single or combined mutation of gyrA and parC genes,carrying the horizontally transferable resistance gene qnrS1.This study provided a reference for rescuing Nipponia nippon and a baseline data for quinolone resistance surveillance of Nipponia nippon.

Key words: Nipponia nippon; quinolone; drug resistance gene; molecular characteristic

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