Molecular Detection of CTX-M Type ESBL Genes in Clinical Isolates of Klebsiella Species
Neesha Shrestha1,
Kuntala Shrestha1, Upendra Thapa Shrestha2, Komal Raj
Rijal2, Gayatri Karki3, Ishworiya Lamichhane1,
Kiran Sapkota4, Sanjib Adhikari2 ,Shyam Prakash Dumre2,
Nabaraj Adhikari2*
1Kantipur College of Medical
Science, Tribhuvan University, Sitapaila, Kathmandu, Nepal
2Central Department of Microbiology,
Tribhuvan University
3Himal Hospital Pvt. Ltd., Thirbum
Marg, Kathmandu
4Sam Houston State University,
Huntsville, Texas, USA
*Corresponding author: Nabaraj Adhikari, Assistant
Professor, Central Department of Microbiology, TU, Email: nabaraj.adhikari@cdmi.tu.edu.np
ABSTRACT
Objective: The objective of
this study is to determine the prevalence of Extended-Spectrum β-Lactamase
(ESBL) production and CTX-M genes among Klebsiella species isolated from
clinical specimens.
Methods: A total of 1,815
clinical samples—including urine, blood, sputum, pus, and body fluids were
collected at Himal Hospital Kathmandu, during 2019–2020. Standard
microbiological techniques were used for isolation and identification of
bacterial pathogens. Antimicrobial susceptibility testing was performed using
the modified Kirby–Bauer disk diffusion method following CLSI (2019)
guidelines. ESBL screening was conducted using third-generation cephalosporins,
and confirmation was done via the Double Disk Synergy Test (DDST). Molecular
detection of the CTX-M gene was performed using PCR with specific primers
targeting a 544 bp amplicon.
Results: Among 1,815
clinical samples, urine constituted the majority (65.8%), followed by blood
(25.1%). Escherichia coli was the predominant isolate (89.1%), while Klebsiella
pneumoniae (6.2%) and Klebsiella oxytoca (0.74%) comprised a smaller
proportion. Of the 28 Klebsiella spp. isolates, the highest antibiotic
sensitivity was observed toward Amikacin (60.7%) and Meropenem (57.1%), whereas
complete resistance to Amoxicillin (100%) and high resistance to Cefixime
(89.3%) and Cefotaxime (75.0%) were recorded. ESBL screening identified 22
(78.6%) potential ESBL producers, of which 18 (64.3%) were confirmed
phenotypically. PCR analysis revealed the CTX-M gene in 7 of the 18
ESBL-positive isolates, demonstrating a notable presence of CTX-M–mediated
resistance among Klebsiella spp.
Conclusion: The findings
highlight a concerning prevalence of ESBL production and CTX-M genes in Klebsiella
species in the study population, underscoring the need for continuous
surveillance, rational antibiotic use, and strengthened antimicrobial
stewardship programs to limit the spread of multidrug-resistant strains.
Keywords: Klebsiella spp., ESBL producer and CTX-M
Date of Submission: November 12, 2025 Date of
Acceptance: December 22, 2025
Published Online: December, 2025 DOI:
https://doi.org/10.3126/tujm.v12i1.88388
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