Molecular epidemiology of antibiotic resistance genes in multiresistant epidemic Salmonella typhimurium DT 104.
Molecular epidemiology of antibiotic resistance genes in multiresistant epidemic Salmonella typhimurium DT 104.
复制标题
多重耐药流行性鼠伤寒沙门氏菌 DT 104 抗生素耐药基因的分子流行病学。
DOI：
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发表时间：
1998
影响因子：
2.6
通讯作者：
E. Threlfall
中科院分区：
文献类型：
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作者：
A. Ridley;E. Threlfall
对人和动物来源的流行性多重耐药鼠伤寒沙门氏菌DT104进行了耐药基因的流行病学调查。从1984-1997年间分离的45株人和21株动物菌株，包括8株从其他欧洲国家、美国、特立尼达和南非分离的对氨苄西林、氯霉素、链霉素、磺胺类、壮观霉素、四环素类(R-型ACSSuSpT)耐药的菌株，用PCR方法检测整合子的存在。在所有对ACSSuSpT产生抗性的菌株中观察到整合子热点，有两个拷贝，由大约1.0和1.2kb的两个离散条带决定。核苷酸直接测序表明，1.0kb的基因产物为ant(3“)-Ia，对链霉素和壮观霉素耐药；1.2kb的扩增产物含有blaPSE-1基因，编码β-内酰胺酶PSE-1(CARB-2)。两个整合子都编码在约10kb的单个XbaI宏限制片段上。这种耐药表型的所有DT 104分离株都含有相同的插入基因盒，无论来源和起源国家，支持流行克隆传播的说法。对15株对奈利地酸和环丙沙星(R型ACSSuSpTNxCp)有额外耐药性的多重耐药菌株的gyrA基因的喹诺酮耐药决定区(QRDR)的序列分析发现，在密码子Asp-87处有两个离散的碱基替换。Asp-87-->；Asn在7/10人和4/5动物分离株中最常见，这表明该密码子在多重耐药鼠伤寒沙门氏菌DT 104对环丙沙星耐药性的形成中起主要作用。
The epidemiology of antibiotic resistance genes in epidemic multiresistant S. typhimurium DT 104 of human and animal origin was investigated. DNA prepared from 45 human and 21 animal strains isolated between 1984 and 1997, including eight isolated in other European countries, the USA, Trinidad, and South Africa and resistant to ampicillin, chloramphenicol, streptomycin, sulphonamides, spectinomycin, tetracyclines (R-type ACSSuSpT) were examined for the presence of integrons by PCR. Integron hot spots were observed in all strains conferring resistance to ACSSuSpT in two copies, determined by two discrete bands of approximately 1.0 and 1.2 kb. Direct nucleotide sequencing of the individual amplicons of selected strains indicated that the 1.0 kb gene product was ant (3")-Ia, responsible for resistance to streptomycin and spectinomycin; the 1.2 kb amplicon contained the gene blaPSE-1, encoding the beta-lactamase PSE-1 (CARB-2). Both integrons were encoded on a single XbaI macrorestriction fragment of approximately 10 kb. All isolates of DT 104 of this resistance phenotype contained the same inserted gene cassettes, irrespective of source and country of origin, supporting the suggestion of the spread of an epidemic clone. Sequence analysis of the quinolone resistance determining region (QRDR) of gyrA of 15 multiresistant strains conferring additional resistance to nalidixic acid and ciprofloxacin (R-type ACSSuSpTNxCp) identified two discrete base substitutions at codon Asp-87. Conversion of Asp-87 --> Asn was most commonly observed, in 7/10 human and 4/5 animal isolates, suggesting that this codon plays a major role in the development of ciprofloxacin resistance in multiresistant S. typhimurium DT 104.