Background: Extended spectrum β-lactamases (ESBL) producing E. coli co-producing other β-lactamases and exhibiting co-resistance to different antibiotic classes continue to emerge as a threat to clinical field. This...Background: Extended spectrum β-lactamases (ESBL) producing E. coli co-producing other β-lactamases and exhibiting co-resistance to different antibiotic classes continue to emerge as a threat to clinical field. This study aimed to analyze the co-production of New Delhi metallo-β-lactamase-1 (blaNDM-1) in ESBL producing plasmid-bearing clinical isolates collected from two tertiary care centres in Kerala, South India, and to understand their genetic relatedness. Methods: Antibiotic resistance phenotypes of 44 clinical isolates were determined by disc-diffusion method. Plasmid-bearing isolates, detected by the alkaline-lysis method, which also tested positive for ESBL production, were screened for the presence of blaNDM-1 by polymerase chain reaction. Plasmid, random amplified polymorphic DNA profiles and blaNDM-1 sequence-based phylogenetic tree were analyzed to understand the genotypic similarities among the isolates. Results: Beta-lactam antibiotics, quinolones, cephalosporins, used in this study, and AZM were found to be ineffective against the isolates as significantly high number of isolates were resistant to these antibiotics (P < 0.01). Plasmid bearing isolates constituted 57% (n = 25), all of which were found to be ESBL producers. blaNDM-1 amplicons were noticed in four (16%) isolates and these DNA sequences showed homology between them and with similar sequences reported from other countries like Japan and Korea. Plasmid and RAPD profiles demonstrated that most of the isolates, including those harbouring blaNDM-1 shared genetic similarities as well as an apparent geographical distinctiveness. Conclusion: The predominance of ESBL production and the occurrence of blaNDM-1 in plasmid-bearing isolates observed in our study corroborate the worldwide drug-resistance scenario. This study thus warrants the need for constant surveillance in the face of sparse information available in Kerala State on the emerging drug resistance in clinical bacteria.展开更多
目的探讨1株碳青霉烯类耐药非脱羧勒克菌的耐药机制。方法采用全自动微生物分析仪、基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)技术及16S r RNA序列分析进行菌种鉴定;采用全自动微生物分析仪进行常规药物敏感性试验,用E-test条检...目的探讨1株碳青霉烯类耐药非脱羧勒克菌的耐药机制。方法采用全自动微生物分析仪、基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)技术及16S r RNA序列分析进行菌种鉴定;采用全自动微生物分析仪进行常规药物敏感性试验,用E-test条检测菌株对亚胺培南的最低抑菌浓度(MIC);改良碳青霉烯酶灭活试验(m CIM法)检测碳青霉烯酶表型;聚合酶链反应(PCR)及测序确定耐药基因型;采用接合试验、S1酶切脉冲场凝胶电泳(S1-PFGE)方法分析其携带质粒的特征。结果临床分离非脱羧勒克菌菌株对亚胺培南、除氨曲南外的其他β内酰胺类抗菌药物及氨基糖苷类耐药,对喹诺酮类和磺胺类药物敏感;接合试验使受体菌E.coli J53获得与非脱羧勒克菌相似的耐药谱。碳青霉烯酶表型试验阳性,PCR扩增及测序表明该菌株同时携带blaNDM-1、blaTEM和aac(6')-Ib,而接合子仅携带blaNDM-1;S1-PFGE示非脱羧勒克菌具有3个质粒。结论非脱羧勒克菌对碳青霉烯类药物耐药为携带blaNDM-1基因造成,该基因可能存在于100 kb左右的可接合传递的质粒上。展开更多
文摘Background: Extended spectrum β-lactamases (ESBL) producing E. coli co-producing other β-lactamases and exhibiting co-resistance to different antibiotic classes continue to emerge as a threat to clinical field. This study aimed to analyze the co-production of New Delhi metallo-β-lactamase-1 (blaNDM-1) in ESBL producing plasmid-bearing clinical isolates collected from two tertiary care centres in Kerala, South India, and to understand their genetic relatedness. Methods: Antibiotic resistance phenotypes of 44 clinical isolates were determined by disc-diffusion method. Plasmid-bearing isolates, detected by the alkaline-lysis method, which also tested positive for ESBL production, were screened for the presence of blaNDM-1 by polymerase chain reaction. Plasmid, random amplified polymorphic DNA profiles and blaNDM-1 sequence-based phylogenetic tree were analyzed to understand the genotypic similarities among the isolates. Results: Beta-lactam antibiotics, quinolones, cephalosporins, used in this study, and AZM were found to be ineffective against the isolates as significantly high number of isolates were resistant to these antibiotics (P < 0.01). Plasmid bearing isolates constituted 57% (n = 25), all of which were found to be ESBL producers. blaNDM-1 amplicons were noticed in four (16%) isolates and these DNA sequences showed homology between them and with similar sequences reported from other countries like Japan and Korea. Plasmid and RAPD profiles demonstrated that most of the isolates, including those harbouring blaNDM-1 shared genetic similarities as well as an apparent geographical distinctiveness. Conclusion: The predominance of ESBL production and the occurrence of blaNDM-1 in plasmid-bearing isolates observed in our study corroborate the worldwide drug-resistance scenario. This study thus warrants the need for constant surveillance in the face of sparse information available in Kerala State on the emerging drug resistance in clinical bacteria.
