Objective: To analyze the molecular mechanism of integron mediated multi-resistance in an ESBL-producing K.pneumoniae NJ 12 isolate. Methods: Susceptibility test was carried out by Kirby-Bauer method. Class Ⅰ, Ⅱ and...Objective: To analyze the molecular mechanism of integron mediated multi-resistance in an ESBL-producing K.pneumoniae NJ 12 isolate. Methods: Susceptibility test was carried out by Kirby-Bauer method. Class Ⅰ, Ⅱ and Ⅲ integrons were detected by integrase gene PCR with primers that annealed to conserved regions of integron-encoded integrase genes intI1, intI2 and intI3. The variable region of integron was amplified by integron PCR with primers that targeted the conserved flanking regions, and the PCR product was sequenced. Six aminoglycoside modifying-enzyme genes, including ant(2″)-Ⅰ, ant(3″)-Ⅰ, aac(3)-Ⅰ, aac(3)-Ⅱ, aac(6′)-Ⅰ, and aac(6′)-Ⅱ, were detected. Results: K.pneumoniae NJ 12 was resistant to nine antibiotics, including piperacillin, ampicillin, cefuroxime, ceftazidime, cefotaxime, aztreonam, streptomycin, gentamicin and amikacin. This isolate was shown that there was positive with class Ⅰ integron, ant(2″)-Ⅰ, ant(3″)-Ⅰ, aac(3)-Ⅱ and aac(6′)-Ⅰ modifying-enzyme genes. Neither class Ⅱ nor Ⅲ integron was detected; DNA sequencing of the fragment amplified by integron PCR revealed a novel cassette array aadB-cat-bla_ oxa-10/ aadA1. Conclusion: Class Ⅰ integron with a novel cassette array in an ESBL-producing multidrug-resistant K.pneumoniae NJ 12 isolate was reported from Nanjing area of China, with the GenBank accession number DQ141319.展开更多
Objective: To investigate the expression of cyclooxygenase-2 (COX-2) mRNA in drug-sensitive cell and drug-resistant clones of ovarian cancer cell lines. Methods: RT-PCR and immunocytochemistry were used to investigate...Objective: To investigate the expression of cyclooxygenase-2 (COX-2) mRNA in drug-sensitive cell and drug-resistant clones of ovarian cancer cell lines. Methods: RT-PCR and immunocytochemistry were used to investigate the expression of cyclooxygenase-2 in 3 clones drug-sensitive and 5 clones drug-resistant ovarian cancer cell. Results: Strong COX-2 mRNA expressions were detected in 3 clones of drug-sensitive cell and weak expressions were detected in 5 clones of drug-resistant cell. The protein expression of COX-2 in drug-sensitive cell was strongly positive reaction in immunocytochemistry stain and there was a weak positive reaction in 5 clones of drug-resistant cell. Conclusion: The expression of COX-2 mRNA in drug-sensitive cell strains is much higher than that in drug-resistant strains of ovarian cancer cell lines, providing a basis of the chemoprevention for ovarian cancer.展开更多
Background There is a growing interest in studying the relationship between intrinsic resistance and biofilms resistance to drugs. However, the relationship still remains unclear in the macroscopic bacterial growth. O...Background There is a growing interest in studying the relationship between intrinsic resistance and biofilms resistance to drugs. However, the relationship still remains unclear in the macroscopic bacterial growth. Our study is to illuminate the change of bacterial drug resistance of gyrA mutant and active efflux pump during the development of Pseudomonas aeruginosa (P. aeruginosa) biofilms. Methods The strains of type Ⅱ topoisomerase gene mutant (gyrA mutant) and multidrug resistance (MDR) efflux pump were clinical isolates and detected by polymerase chain reaction (PCR). The process of bacterial biofilms development was observed by scanning electron microscope. Triparental mating experiments were performed to transfer report gene of green fluorescent protein (GFP) into P. aeruginosa biofilms strains and followed by analysis of bacterial survival rate between intrinsic resistance and biofilms resistance.Results The fluorescent strains with pGFPuv could develop mature biofilms on Teflon surface. Before a period of 72 hours, the survival rate of biofilms bacteria and intrinsic resistance strains in ciprofloxacin solution was significantly different (P<0.05). The survival number of intrinsic resistance strains (gyrA mutation and active efflux pump) was illustriously higher than biofilm strain in the initial stage of biofilms development. After 72 hours incubation, there was no clearly difference between mutants and biofilms strains in the survival rate (P>0.05). The carbonyl cyanide m-chlorophenylhydrazone and azithromycin could significantly reduce the drug resistance of biofilm strains and efflux pump strains.Conclusions In the development of P. aeruginosa biofilms, the strains of gyrA mutation and MDR efflux could be conferred with new level of drug resistance. When co-cultured mutated strains with biofilm strains, biofilms may play a major role in bacterial resistance. But after 72 hours incubation (a mature biofilms had been developed), there was no clearly difference between the number of mutant strains and biofilm strains.展开更多
文摘Objective: To analyze the molecular mechanism of integron mediated multi-resistance in an ESBL-producing K.pneumoniae NJ 12 isolate. Methods: Susceptibility test was carried out by Kirby-Bauer method. Class Ⅰ, Ⅱ and Ⅲ integrons were detected by integrase gene PCR with primers that annealed to conserved regions of integron-encoded integrase genes intI1, intI2 and intI3. The variable region of integron was amplified by integron PCR with primers that targeted the conserved flanking regions, and the PCR product was sequenced. Six aminoglycoside modifying-enzyme genes, including ant(2″)-Ⅰ, ant(3″)-Ⅰ, aac(3)-Ⅰ, aac(3)-Ⅱ, aac(6′)-Ⅰ, and aac(6′)-Ⅱ, were detected. Results: K.pneumoniae NJ 12 was resistant to nine antibiotics, including piperacillin, ampicillin, cefuroxime, ceftazidime, cefotaxime, aztreonam, streptomycin, gentamicin and amikacin. This isolate was shown that there was positive with class Ⅰ integron, ant(2″)-Ⅰ, ant(3″)-Ⅰ, aac(3)-Ⅱ and aac(6′)-Ⅰ modifying-enzyme genes. Neither class Ⅱ nor Ⅲ integron was detected; DNA sequencing of the fragment amplified by integron PCR revealed a novel cassette array aadB-cat-bla_ oxa-10/ aadA1. Conclusion: Class Ⅰ integron with a novel cassette array in an ESBL-producing multidrug-resistant K.pneumoniae NJ 12 isolate was reported from Nanjing area of China, with the GenBank accession number DQ141319.
基金National Natural Science Foundation of China (No.30070786)
文摘Objective: To investigate the expression of cyclooxygenase-2 (COX-2) mRNA in drug-sensitive cell and drug-resistant clones of ovarian cancer cell lines. Methods: RT-PCR and immunocytochemistry were used to investigate the expression of cyclooxygenase-2 in 3 clones drug-sensitive and 5 clones drug-resistant ovarian cancer cell. Results: Strong COX-2 mRNA expressions were detected in 3 clones of drug-sensitive cell and weak expressions were detected in 5 clones of drug-resistant cell. The protein expression of COX-2 in drug-sensitive cell was strongly positive reaction in immunocytochemistry stain and there was a weak positive reaction in 5 clones of drug-resistant cell. Conclusion: The expression of COX-2 mRNA in drug-sensitive cell strains is much higher than that in drug-resistant strains of ovarian cancer cell lines, providing a basis of the chemoprevention for ovarian cancer.
文摘Background There is a growing interest in studying the relationship between intrinsic resistance and biofilms resistance to drugs. However, the relationship still remains unclear in the macroscopic bacterial growth. Our study is to illuminate the change of bacterial drug resistance of gyrA mutant and active efflux pump during the development of Pseudomonas aeruginosa (P. aeruginosa) biofilms. Methods The strains of type Ⅱ topoisomerase gene mutant (gyrA mutant) and multidrug resistance (MDR) efflux pump were clinical isolates and detected by polymerase chain reaction (PCR). The process of bacterial biofilms development was observed by scanning electron microscope. Triparental mating experiments were performed to transfer report gene of green fluorescent protein (GFP) into P. aeruginosa biofilms strains and followed by analysis of bacterial survival rate between intrinsic resistance and biofilms resistance.Results The fluorescent strains with pGFPuv could develop mature biofilms on Teflon surface. Before a period of 72 hours, the survival rate of biofilms bacteria and intrinsic resistance strains in ciprofloxacin solution was significantly different (P<0.05). The survival number of intrinsic resistance strains (gyrA mutation and active efflux pump) was illustriously higher than biofilm strain in the initial stage of biofilms development. After 72 hours incubation, there was no clearly difference between mutants and biofilms strains in the survival rate (P>0.05). The carbonyl cyanide m-chlorophenylhydrazone and azithromycin could significantly reduce the drug resistance of biofilm strains and efflux pump strains.Conclusions In the development of P. aeruginosa biofilms, the strains of gyrA mutation and MDR efflux could be conferred with new level of drug resistance. When co-cultured mutated strains with biofilm strains, biofilms may play a major role in bacterial resistance. But after 72 hours incubation (a mature biofilms had been developed), there was no clearly difference between the number of mutant strains and biofilm strains.
