Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
Foodborne Pathog Dis. 2010 Jan;7(1):91-5. doi: 10.1089/fpd.2009.0382.
The infections caused by Salmonella remain a significant public health problem throughout the world. beta-Lactams and fluoroquinolones are generally used to treat invasive Salmonella infections, but emergence and spread of antibiotic-resistant strains are being increasingly notified in many countries. In particular, detection of extended-spectrum beta-lactamases (ESBLs) in Salmonella spp. is a newly emerging threat worldwide. This study was carried out to characterize beta-lactamase-producing Salmonella strains identified in Tehran, Iran. Over the 2-year period from 2007 to 2008, 6 of 136 Salmonella isolates recovered from pediatrics patients, including three Salmonella enterica serotypes Enteritidis (S. Enteritidis) and three S. Infantis, showed an ESBL-positive phenotype. Polymerase chain reaction and sequencing were used to identify the genetic determinants responsible for ESBL phenotypes. The Salmonella isolates were also compared by pulsed-field gel electrophoresis. All ESBL-producing strains, but one, carried the bla(CTX-M-15) gene. Moreover, three of four strains that proved to be positive for a bla(TEM) gene were producing a TEM-1 beta-lactamase. Two strains of S. Infantis tested positive for a previously unidentified CTX-M and TEM ESBL, respectively. All ESBL-producing strains carried the insertion sequence ISEcp1 gene. Except for one strain of serotype Infantis, all strains were able to transfer the ESBL determinants by conjugation. Distinct, but closely related, pulsed-field gel electrophoresis patterns were observed among the strains belonging to both serotypes. This study reports for the first time the emergence and characterization of ESBL-producing S. Enteritidis and Infantis strains in Iran.
沙门氏菌引起的感染仍然是全世界一个重大的公共卫生问题。通常使用β-内酰胺类和氟喹诺酮类药物来治疗侵袭性沙门氏菌感染，但在许多国家，抗生素耐药菌株的出现和传播越来越受到关注。特别是，在沙门氏菌属中检测到的扩展谱β-内酰胺酶（ESBLs）是全世界新出现的威胁。本研究旨在对在伊朗德黑兰鉴定的产β-内酰胺酶沙门氏菌菌株进行特征描述。在 2007 年至 2008 年的 2 年期间，从儿科患者中分离出的 136 株沙门氏菌分离株中，有 6 株（包括 3 株肠炎沙门氏菌和 3 株婴儿沙门氏菌）表现出 ESBL 阳性表型。聚合酶链反应和测序用于鉴定负责 ESBL 表型的遗传决定因素。沙门氏菌分离株还通过脉冲场凝胶电泳进行比较。所有产 ESBL 株，但有一株，携带 bla(CTX-M-15)基因。此外，被证明 bla(TEM)基因阳性的 4 株菌中的 3 株产 TEM-1 型β-内酰胺酶。两种婴儿沙门氏菌菌株分别对以前未识别的 CTX-M 和 TEM ESBL 呈阳性。所有产 ESBL 株均携带插入序列 ISEcp1 基因。除了一株婴儿沙门氏菌血清型外，所有菌株均能通过 conjugation 转移 ESBL 决定簇。属于两种血清型的菌株观察到不同但密切相关的脉冲场凝胶电泳模式。本研究首次报告了 ESBL 产肠炎沙门氏菌和婴儿沙门氏菌在伊朗的出现和特征描述。
