Africa has experienced rapid urban migration in the past two decades. New informal settlements continue to emerge and expand but the sanitation provision of facilities has not improved at the same pace and this poses ...Africa has experienced rapid urban migration in the past two decades. New informal settlements continue to emerge and expand but the sanitation provision of facilities has not improved at the same pace and this poses a serious health concern to the public especially the urban poor. Open sewage systems and sludge-clogged drainage systems as well as soil contaminated with industrial and domestic wastes are possible sources of germs that probably cause clinical infections and epidemics. In this cross-sectional study, we recorded diverse genera of Gram-negative non-fastidious bacteria that included;Escherichia coli (23%), Klebsiella spp (21%), Enterobacter spp (19%), Citrobacter spp (10%), Pseudomonas aeruginosa (8%), Proteus spp (7%), Salmonella (3%), Yersinia spp (3%), Shigella spp (2%), Morganella morganii (2%), Edwardisella spp (1%), Hafnia spp (1%), Serratia marcesence (0.5%), and Acinetobacter baumannii (0.5%). Most of these isolates were resistant to ampicillin while imipenem and ciprofloxacin were the most effective antimicrobial agents. Resistance combination towards ampicillin, trimethoprim, sulfamethoxazole and streptomycin was also noted in recovered isolates (16%). An overall high antimicrobial resistance was recorded among isolates from slum as compared to those recovered from Juja, a middle-class settlement located at the edge of Nairobi metropolis. The prevalence of isolates with a combined resistance to 3rd generation cephalosporins (cefotaxime, ceftriaxone and ceftazidime), gentamicin and ciprofloxacin was the highest among P. aeruginosa isolates (13%) but none of the Yersinia species and Edwardisella tarda exhibited this resistance. Carriage of blaTEM (52%) was most prevalent in all bacteria species followed by blaCTX-M (20%), blaSHV (18%) while blaOXA (17%) was the least common. The phylogeny analysis revealed significant genetic similarity among strains belonging to E. coli, K. pneumoniae, E. agglomerans and P. mirabilis strains but less relatedness was noted among strains belonging to C. freundi展开更多
抗生素抗性基因(antibiotic resistance genes,ARGs)作为一种新型的环境污染物,成为多个学科关注的焦点.其在不同环境介质中的扩散和传播具有极大的环境危害性,对人类健康造成严重威胁.插入序列共同区(insertion sequence common region...抗生素抗性基因(antibiotic resistance genes,ARGs)作为一种新型的环境污染物,成为多个学科关注的焦点.其在不同环境介质中的扩散和传播具有极大的环境危害性,对人类健康造成严重威胁.插入序列共同区(insertion sequence common region,ISCR),是一种新发现的抗性基因传播元件,因其特殊的遗传结构,能够通过滚环复制及同源重组等机制移动邻近的任何DNA序列,是ARGs在不同DNA分子或不同种属细菌间水平传播的高效媒介.目前世界上发现了27种ISCR元件.大量间接证据表明,ISCR可能与许多耐药基因的移动和扩散有关,特别是多重耐药性(multiple drug resistance,MDR)形成与传播.因此,ISCR很可能是抗生素抗性基因在环境中扩散传播的关键因子.本文就ARGs水平传播、ISCR结构特征、ISCR种类及其相关ARGs及其研究方法等进行综述,并揭示ISCR元件可能的生态风险,提出了今后的研究重点,以期为今后深入开展相关研究打下基础.展开更多
多药耐药基因1(multiple drug resistance gene 1,MDR1)编码的P-糖蛋白(P-glycoprotein,P-gp)可导致多种药物耐药。MDR1基因可能与繁殖器官有密切联系。本研究以长白、大约克、杜洛克和金华母猪为试验群体,通过直接测序的方法检测MDR1...多药耐药基因1(multiple drug resistance gene 1,MDR1)编码的P-糖蛋白(P-glycoprotein,P-gp)可导致多种药物耐药。MDR1基因可能与繁殖器官有密切联系。本研究以长白、大约克、杜洛克和金华母猪为试验群体,通过直接测序的方法检测MDR1基因的多态性,并对母猪的繁殖性能指标进行了关联分析,探讨MDR1基因多态性对母猪繁殖性状的影响。结果表明:MDR1基因外显子1有一处G→A的突变,存在GG、AG、AA3种基因型,等位基因G为优势等位基因,GG基因型为优势等位基因;MDR1基因多态性对初产和经产长白、大约克、杜洛克和金华母猪群体的总产仔数、产活仔数和初生窝重有显著影响(P<0.05)。综合结果分析,MDR1基因多态性对猪的繁殖性能存在影响,可作为潜在的遗传标记,为猪的分子育种提供参考。展开更多
文摘Africa has experienced rapid urban migration in the past two decades. New informal settlements continue to emerge and expand but the sanitation provision of facilities has not improved at the same pace and this poses a serious health concern to the public especially the urban poor. Open sewage systems and sludge-clogged drainage systems as well as soil contaminated with industrial and domestic wastes are possible sources of germs that probably cause clinical infections and epidemics. In this cross-sectional study, we recorded diverse genera of Gram-negative non-fastidious bacteria that included;Escherichia coli (23%), Klebsiella spp (21%), Enterobacter spp (19%), Citrobacter spp (10%), Pseudomonas aeruginosa (8%), Proteus spp (7%), Salmonella (3%), Yersinia spp (3%), Shigella spp (2%), Morganella morganii (2%), Edwardisella spp (1%), Hafnia spp (1%), Serratia marcesence (0.5%), and Acinetobacter baumannii (0.5%). Most of these isolates were resistant to ampicillin while imipenem and ciprofloxacin were the most effective antimicrobial agents. Resistance combination towards ampicillin, trimethoprim, sulfamethoxazole and streptomycin was also noted in recovered isolates (16%). An overall high antimicrobial resistance was recorded among isolates from slum as compared to those recovered from Juja, a middle-class settlement located at the edge of Nairobi metropolis. The prevalence of isolates with a combined resistance to 3rd generation cephalosporins (cefotaxime, ceftriaxone and ceftazidime), gentamicin and ciprofloxacin was the highest among P. aeruginosa isolates (13%) but none of the Yersinia species and Edwardisella tarda exhibited this resistance. Carriage of blaTEM (52%) was most prevalent in all bacteria species followed by blaCTX-M (20%), blaSHV (18%) while blaOXA (17%) was the least common. The phylogeny analysis revealed significant genetic similarity among strains belonging to E. coli, K. pneumoniae, E. agglomerans and P. mirabilis strains but less relatedness was noted among strains belonging to C. freundi
文摘抗生素抗性基因(antibiotic resistance genes,ARGs)作为一种新型的环境污染物,成为多个学科关注的焦点.其在不同环境介质中的扩散和传播具有极大的环境危害性,对人类健康造成严重威胁.插入序列共同区(insertion sequence common region,ISCR),是一种新发现的抗性基因传播元件,因其特殊的遗传结构,能够通过滚环复制及同源重组等机制移动邻近的任何DNA序列,是ARGs在不同DNA分子或不同种属细菌间水平传播的高效媒介.目前世界上发现了27种ISCR元件.大量间接证据表明,ISCR可能与许多耐药基因的移动和扩散有关,特别是多重耐药性(multiple drug resistance,MDR)形成与传播.因此,ISCR很可能是抗生素抗性基因在环境中扩散传播的关键因子.本文就ARGs水平传播、ISCR结构特征、ISCR种类及其相关ARGs及其研究方法等进行综述,并揭示ISCR元件可能的生态风险,提出了今后的研究重点,以期为今后深入开展相关研究打下基础.
文摘多药耐药基因1(multiple drug resistance gene 1,MDR1)编码的P-糖蛋白(P-glycoprotein,P-gp)可导致多种药物耐药。MDR1基因可能与繁殖器官有密切联系。本研究以长白、大约克、杜洛克和金华母猪为试验群体,通过直接测序的方法检测MDR1基因的多态性,并对母猪的繁殖性能指标进行了关联分析,探讨MDR1基因多态性对母猪繁殖性状的影响。结果表明:MDR1基因外显子1有一处G→A的突变,存在GG、AG、AA3种基因型,等位基因G为优势等位基因,GG基因型为优势等位基因;MDR1基因多态性对初产和经产长白、大约克、杜洛克和金华母猪群体的总产仔数、产活仔数和初生窝重有显著影响(P<0.05)。综合结果分析,MDR1基因多态性对猪的繁殖性能存在影响,可作为潜在的遗传标记,为猪的分子育种提供参考。
