SHV-7, A NOVEL CEFOTAXIME-HYDROLYZING BETA-LACTAMASE, IDENTIFIED IN ESCHERICHIA-COLI ISOLATES FROM HOSPITALIZED NURSING-HOME PATIENTS
SHV-7, A NOVEL CEFOTAXIME-HYDROLYZING BETA-LACTAMASE, IDENTIFIED IN ESCHERICHIA-COLI ISOLATES FROM HOSPITALIZED NURSING-HOME PATIENTS
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DOI：
10.1128/aac.39.4.899
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发表时间：
1995-04-01
影响因子：
4.9
通讯作者：
BUSH, K
中科院分区：
文献类型：
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作者：
BRADFORD, PA;URBAN, C;BUSH, K
1993年，从纽约一家医院的老年疗养院患者中分离出4株头孢他啶耐药大肠杆菌。菌株MCQ-2，MCQ-3和MCQ-4被确定为相同的脉冲场凝胶电泳和质粒谱，而菌株MCQ-1是独特的。确定菌株MCQ-1产生TEM-10 β-内酰胺酶。菌株MCQ-2、MCQ-3和MCQ-4也对头孢噻肟耐药。这三种菌株产生两种β-内酰胺酶，pI为5.4（TEM-1）和7.6。β-内酰胺酶测定显示，pI 7.6酶水解头孢噻肟的速度（与苄青霉素相比，相对水解率为30%）比头孢他啶或氨曲南（相对水解率分别为13%和3.3%）更快。对来自菌株MCQ-3的编码pI 7.6 β-内酰胺酶的基因的核苷酸测序揭示了与编码SHV-1的基因在四个核苷酸处不同的bla（SHV）型基因，这导致氨基酸取代：在位置8处苯丙氨酸取代异亮氨酸，在位置43处丝氨酸取代精氨酸，在位置238处丝氨酸取代甘氨酸，以及在位置240处赖氨酸取代谷氨酸。这种新型SHV型超广谱β-内酰胺酶被命名为SHV-7。
Four ceftazidime-resistant Escherichia coli strains were isolated from elderly nursing home patients in a New York hospital during 1993. Strains MCQ-2, MCQ-3, and MCQ-4 were determined to be identical by pulsed-field gel electrophoresis and plasmid profiles, whereas strain MCQ-1 was unique. Strain MCQ-1 was determined to produce a TEM-10 beta-lactamase. Strains MCQ-2, MCQ-3, and MCQ-4 were also noted to be resistant to cefotaxime. These three strains produced two beta-lactamases with pIs of 5.4 (TEM-1) and 7.6. beta-Lactamase assays revealed that the pI 7.6 enzyme hydrolyzed cefotaxime faster (at a relative hydrolysis rate of 30% compared with that of benzylpenicillin) than either ceftazidime or aztreonam (relative hydrolysis rates of 13 and 3.3%, respectively). Nucleotide sequencing of the gene encoding the pI 7.6 beta-lactamase from strain MCQ-3 revealed a bla(SHV)-type gene differing from the gene encoding SHV-1 at four nucleotides which resulted in amino acid substitutions: phenylalanine for isoleucine at position 8, serine for arginine at position 43, serine for glycine at position 238, and lysine for glutamate at position 240. This novel SHV-type extended-spectrum beta-lactamase is designated SHV-7.