The Open Microbiology Journal

ISSN: 1874-2858 ― Volume 14, 2020

Predominance of CTX-M Type Extended Spectrum β-lactamase (ESBL) Producers Among Clinical Isolates of Enterobacteriaceae in a Tertiary Care Hospital, Kathmandu, Nepal

Biraj Lohani1, 2, *, Mina Thapa1, Laxmi Sharma3, Hriush Adhikari4, Anil K. Sah3, Arun B. Khanal5, Ranga B. Basnet6, Manita Aryal1
1 Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal
2 Department of Microbiology, Pinnacle College, Lalitpur, Nepal
3 Annapurna Research Center, Kathmandu, Nepal
4 SANN International College, Kathmandu, Nepal
5 Nobel College, Kathmandu, Nepal
6 Annapurna Neurological Institute and Allied Sciences, Kathmandu, Nepal



ESBL problem is increasing worldwide and only limited studies on genes of ESBL are performed in Nepal.


We aimed to focus on the molecular detection of plasmid-mediated blaTEM, blaSHV and blaCTX-M genes among the ESBL producing Enterobacteriaceae from different clinical samples.


A total of 550 clinical samples were processed and organisms of Enterobacteriaceae were identified using standard microbiological process. ESBL producers were screened and confirmed using modified Kirby Bauer disc diffusion method by CLSI guidelines. Plasmids extracted from the confirmed ESBL positives were the template for PCR. blaSHV, blaTEM and blaCTX-M genes were amplified using specific primers of respective genes by uniplex PCR. The presence of these genes was confirmed by gel electrophoresis.


Among 550 different clinical samples 343 (62.36%) were culture positive. Of which, 157 (45.57%) belonged to Enterobacteriaceae. Escherichia coli (45.9%) was predominant. Of these 33.2% (52/157) isolates ESBL positive. ESBL- E. coli (52.8%) were prevalent. All ESBL positive organisms were sensitive to imipenem. Of confirmed ESBL positives, 34.6% harboring blaTEM gene, 30.8% harboring blaSHV gene and blaCTX-M genes were present in all ESBL producers. Twenty-eightout of 52 (53.9%) isolates harbored multiple bla genes, the most common combination being blaCTX-M + blaTEM (21.2%).


We report 100% plasmid mediated CTX-M genotype among ESBL producers which might indicate rapid dissemination of blaCTX-Mgenes from the community to the patients. Besides, there is a need for regular monitoring of antibiotic resistance in the country and de-escalate the use of antibiotics so as to preserve the antibiotics for future generation.

Keywords: ESBL, Enterobacteriaceae, BlaTEM, BlaSHV, BlaCTX-M, Gel electrophoresis.

Article Information

Identifiers and Pagination:

Year: 2019
Volume: 13
First Page: 28
Last Page: 33
Publisher Id: TOMICROJ-13-28
DOI: 10.2174/1874285801913010028

Article History:

Received Date: 17/10/2018
Revision Received Date: 15/1/2019
Acceptance Date: 16/1/2019
Electronic publication date: 31/01/2019
Collection year: 2018

© 2019 Lohani et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu, Nepal,Department of Microbiology, Pinnacle College, Lalitpur, Nepal; Tel: +9779803737583; E-mail:

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