Banerjee Tuhina, Bhattacharjee Amitabha, Upadhyay Supriya, Mishra Shweta, Tiwari Karuna, Anupurba Shampa, Sen Malay Ranjan, Basu Sriparna, Kumar Ashok
Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
Department of Microbiology, Assam University, Silchar, India.
Indian J Med Res. 2016 Oct;144(4):622-629. doi: 10.4103/0971-5916.200900.
BACKGROUND & OBJECTIVES: The indiscriminate use of third generation cephalosporin has contributed to the emergence and widespread dissemination of extended spectrum β lactamases (ESBL) genes in Klebsiella pneumoniae. This study was undertaken to elaborate the genetic behaviour of ESBL - producing K. pneumoniae isolates in the neonatal intensive care unit (NICU) of a tertiary care hospital in north India causing successive outbreaks in context with empirical third generation cephalosporin use.
Isolates of K. pneumoniae (43 from blood, 3 from pus and endotracheal tube, 4 from environment) causing successive outbreaks in the NICU of a tertiary care university hospital were studied for two years. Antimicrobial susceptibility testing was done by disc diffusion and minimum inhibitory concentration (MIC) determination by agar dilution methods. ESBL production was determined by phenotypic and genotypic methods. Clonal relatedness among the isolates was studied by enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR). Genetic environment of these isolates was assessed by the presence of integrons and gene cassettes. Transformation experiments were done, and plasmids of these isolates were characterized by stability testing and incompatibility testing. Subsequently, a change in the ongoing antibiotic policy was adopted, and corresponding changes in the behaviour of these isolates studied.
During the period from August 2011 to January 2013, 46 isolates of monoclonal ESBL K. pneumoniae were obtained from different neonates and four similar environmental isolates were studied. Multidrug-resistant ESBL isolates harboured both blaCTXM-15 and bla SHV-5. The dfr and aac-6 ' resistant genes were found in gene cassettes. A 50 kb plasmid belonging to IncFIIA group was detected in all the isolates which was transferable and stable. The emergence and regression of the outbreaks coincided with antibiotic usage in the NICU, with widespread empirical use of cefotaxime being responsible for their persistence in the environment.
INTERPRETATION & CONCLUSIONS: The study indicates that empirical use of third generation cephalosporins may promote the emergence, persistence, and dissemination of resistant isolates in the hospital environment. Periodic review of antibiotic policy is necessary for rationalized use of antibiotics.
第三代头孢菌素的滥用促使肺炎克雷伯菌中广谱β-内酰胺酶（ESBL）基因的出现和广泛传播。本研究旨在阐述印度北部一家三级医院新生儿重症监护病房（NICU）中产ESBL肺炎克雷伯菌分离株的遗传行为，该分离株在经验性使用第三代头孢菌素的情况下引发了连续疫情。
对一家三级大学医院NICU中引发连续疫情的肺炎克雷伯菌分离株（43株来自血液，3株来自脓液和气管内导管，4株来自环境）进行了为期两年的研究。采用纸片扩散法进行药敏试验，通过琼脂稀释法测定最低抑菌浓度（MIC）。通过表型和基因型方法确定ESBL的产生。采用肠杆菌重复基因间共有序列聚合酶链反应（ERIC-PCR）研究分离株之间的克隆相关性。通过整合子和基因盒的存在评估这些分离株的遗传环境。进行了转化实验，并通过稳定性测试和不相容性测试对这些分离株的质粒进行了鉴定。随后，采用了正在进行的抗生素政策的变化，并研究了这些分离株行为的相应变化。
在2011年8月至2013年1月期间，从不同新生儿中获得了46株单克隆产ESBL肺炎克雷伯菌分离株，并对4株相似的环境分离株进行了研究。多重耐药产ESBL分离株同时携带blaCTXM-15和blaSHV-5。在基因盒中发现了dfr和aac-6′耐药基因。在所有分离株中检测到一个属于IncFIIA组的50 kb质粒，该质粒可转移且稳定。疫情的出现和消退与NICU中的抗生素使用情况一致，头孢噻肟的广泛经验性使用导致其在环境中持续存在。
该研究表明，第三代头孢菌素的经验性使用可能会促进医院环境中耐药分离株的出现、持续存在和传播。定期审查抗生素政策对于合理使用抗生素是必要的。
