A plasmid of mediateable recipient bacteria with decreased sensibility to quinolones antibacterial drugs
A quinolone and antibacterial drug technology, applied in the field of microbiology, can solve the problems of clinical drug resistance, decreased sensitivity, quinolone drug resistance, etc.
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Embodiment 1
[0043] Cloning and screening of quinolone resistance genes from clinically isolated Gram-negative bacilli
[0044] Step 1. Plasmid-mediated screening of unknown quinolone-resistant gene clinical strains
[0045] Collect clinical isolates of Gram-negative bacilli with reduced sensitivity to quinolones, use PCR to detect known drug-resistant genes qnrA, qnrB, and qnrS, and retain known drug-resistant gene-negative strains for follow-up research;
[0046] Step 2: Acquisition of plasmids containing unknown quinolone resistance genes
[0047] The known drug-resistant gene-negative Gram-negative bacillus clinical isolate obtained in step 1 is used as the donor bacterium, and E.coliJ53AzR is used as the recipient bacterium for the conjugation experiment (for specific methods, refer to the literature Antimicrob.Agents Chemother.2003, 47: 2242- 2248.). Obtained from the clinically isolated Proteus mirabilis No. 06-489 (preserved in the General Microorganism Center of China Committee ...
Embodiment 2
[0053] Sequence analysis confirmed the new drug resistance gene qnrC
[0054] Step 1 is to clarify that quinolone resistance is mediated by the qnrC gene, exclude the influence of the upstream and downstream genes of qnrC, clone qnrC again, and use primers Primer1 and Pimer3 to amplify a fragment containing only the full sequence of qnrC and clone it into pMD19( Takara, Dalian, China), and transformed into DH5α, the above-mentioned ampicillin screening plate was used to screen the transformant, and the transformant containing the recombinant plasmid also had increased drug resistance to ciprofloxacin. However, the fragment amplified with primers Primer2 and Primer3 without the complete sequence of qnrC was cloned into pMD19, and the transformants screened by ampicillin screening plate had no increased drug resistance to ciprofloxacin although they contained recombinant plasmids , further verified that quinolone resistance was caused by qnrC.
[0055] Step 2 is to further conf...
Embodiment 3
[0057] Establish the PCR method for detecting qnrC gene according to the sequence of the present invention
[0058] Step 1. Primer Design
[0059] Input the nucleotide sequence of the present invention into oligo software for primer design, select primers from the primer sequences screened by the software, the expected product size is 395bp, and the primer sequences are as follows:
[0060] qnrC AF5'-GGGTTGTACATTTATTGAATC-3'
[0061] qnrC AR5'-CCTGAATTCTGCATTGCTC-3'
[0062] Step 2 Optimize PCR amplification conditions
[0063] Takara Taq reagents were used to prepare the PCR reaction system, and the annealing temperature was optimized on the TP600 TakaraPCR Thermal cycler dice amplification instrument with gradient heating and cooling functions. The final determination was 94°C for 5 minutes, 94°C for 30 seconds, 50°C for 30 seconds, and 72°C. 30 cycles in 30 seconds, the amplification effect is the best when extending for 5 minutes at 72°C.
[0064] Step 3 Sequence Analy...
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