Detection of carbapenem resistance and its attributable genes in Acinetobacter baumannii isolated from cardiac patients at a referral cardiac hospital of Kathmandu

Abstract

Objective: Acinetobacter baumannii has emerged as a major nosocomial pathogen due to its remarkable ability to develop resistance to multiple antibiotics including carbapenems. The objective of this study was to assess the carbapenem resistance and detect carbapenem-resistant genes in clinical isolates of A. baumannii.

Methods: A cross-sectional study was conducted in Shahid Gangalal National Heart Centre, Kathmandu during February to September 2024. A total of 42 A. baumannii were isolated from different clinical specimens and identified. Antibiotic susceptibility test was performed by Kirby-Bauer disc diffusion method and carbapenemase production was assessed using modified carbapenem inactivation method and EDTA-carbapenem inactivation method. Carbapenem-resistant genes were detected through polymerase chain reaction. Among 1607 samples tested, 349 were culture positive for bacteria.

Results: The prevalence of A. baumannii was 12% (42/349). Among the 42 A. baumannii isolates, 88.1% were resistant to carbapenems. Metallo-β-lactamase production was observed in 35.7% and multidrug resistance in 83.3% isolates. Resistance rates were highest against cefotaxime, cefepime and carbapenems. The blaOXA-23 gene was detected in 69.1% of the isolates, blaNDM-1 in 66.7%, and blaVIM in 14.3%, but none of the isolates harbored the blaIMP. Co-occurrence of blaOXA-23 and blaNDM-1 genes was detected in 20 (47.6%) isolates, blaOXA-23, blaNDM-1 and blaVIM in 4 (9.5%) isolates, and blaNDM-1 and blaVIM in 1 (2.4%) isolate.

Conclusion: This study showed a high burden of carbapenems resistant and multi-drug resistant A. baumannii, likely contributed by the co-occurrence of carbapenem resistant genes. These findings provide valuable insights for clinical management and infection control of A. baumannii.

Keywords: Carbapenem resistance, MDR, Gene co-existence, Acinetobacter baumannii

Citation: B K P, Khadka S, Shrestha UT, Banjara MR. Detection of carbapenem resistance and its attributable genes in Acinetobacter baumannii isolated from cardiac patients at a referral cardiac hospital of Kathmandu. BMC Microbiol. 2026 Jan 9;26(1):128. doi: 10.1186/s12866-025-04692-z. PMID: 41507808; PMCID: PMC12911273.

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Antibiofilm Activity of Bacteriophage Isolated from Sewage-Polluted Water against Escherichia coli

 

Antibiofilm Activity of Bacteriophage Isolated from Sewage-Polluted Water against Escherichia coli

Acharya Amrit^{1, 2}, Ayushma Tamrakar^1†, Smirti Yando^1†, Avinash Chaudhary¹, Upendra Thapa Shrestha^1,2, Dev Raj Joshi², Binod Lekhak²

 

¹ Department of Microbiology, Sainik Awasiya Mahavidhyalaya, Bhaktpur, Nepal

² Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal

†The first three authors contributed equally.

*Corresponding author: Amrit Acharya, Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal, E-mail: amrit.805710@iost.tu.edu.np

ABSTRACT

 

Objectives: This study aimed to explore bacteriophages, viruses that infect bacteria, as an alternative antibiofilm agent.

Methods: A laboratory-based, cross-sectional study was conducted at the Sainik Awasiya Mahavidyalaya Laboratory from February to July 2025. The water samples that were contaminated with effluents were collected from eight rivers and ponds across the Kathmandu valley. E. coli isolates were used as the host strain after being confirmed by biochemical tests. Phages were isolated and enriched from wastewater using centrifugation, filtration, and multiple cycles of incubation with log-phage host bacteria to gain high titres. The plaque assay, host range by spot assay, and Efficacy of Plating (EOP) were performed. Antibiofilm activity was evaluated using the microtiter plate crystal violet assay. The study compared biofilm formation in the isolated E. coli (E.C 8) with that of the standard E. coli (ATCC 8739). Statistical significance was determined using the t-test (p ≤ 0.05).

Results: Bacteriophages were found in six of eight samples. Only Mulpani had a lytic phage with a titre of 7.5 PFU/ml, which was used for further testing. The phage exhibited moderate EOP, ranging from 0.28 to 0.60, and a moderate host range. The isolated phage showed selected antibiofilm activity, as it effectively reduced the biofilm of the isolated E. coli (22.8%).

Conclusion: This emphasizes the ability of lytic phages as antibiofilm agents.

 

Keywords: Effluent, Antibiotic Resistance, Biofilm, Extracellular Polymeric Substances, Bacteriophage

 

Date of Submission: November 03, 2025     Date of Acceptance: December 05, 2025

Published Online: December, 2025               DOI: https://doi.org/10.3126/tujm.v12i1.88373

Citation: Acharya, A., Tamrakar, A., Yando, S., Chaudhary, A., Thapa Shrestha, U., Joshi, D. R., & Lekhak, B. (2025). Antibiofilm Activity of Bacteriophage Isolated from Sewage-Polluted Water against Escherichia coli. Tribhuvan University Journal of Microbiology, 12(1), 89–99. https://doi.org/10.3126/tujm.v12i1.88373

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Quinolones residue in poultry meat and eggs; an alarming public health issue in Nepal (BMC Research Notes)

  

Quinolones residue in poultry meat and eggs; an alarming public health issue in Nepal

Nabaraj Shrestha¹, Sundar Layalu², Serene Amatya³, Samrat Shrestha³, Shobha Basnet⁴, Divya Pradhan⁵ and Upendra Thapa Shrestha^{5 *}

¹Department of Livestock Services, Hariharbhawan, Lalitpur, Nepal

²Clark University, Worcester, USA

³Himalayan College of Agricultural Sciences and Technology (HICAST), Kalanki, Kathmandu, Nepal

⁴ZEST Laboratory, Bhaktapur, Balkot, Nepal

⁵Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu, Nepal

 

*Correspondence: Upendra Thapa Shrestha; upendrats@gmail.com; upendra.thapashrestha@cdmi.tu.edu.np

 

 Abstract

Objective Quinolones, critically important antimicrobials, pose public health risks due to potential antimicrobial resistance, allergic reactions, and other toxicities when residues persist in food. This study aimed to qualitatively and quantitatively assess quinolone residues in chicken meat and eggs supplied to Kathmandu, Nepal. Additionally, data on antibiotic usage trends were collected through a standardized questionnaire using Epicollect + Android application. A total of 120 chicken meat and 120 eggs were collected from five designated sectors. Initial screening for quinolone residues was performed using Enzyme-Linked Immunosorbent Assay, and samples exceeding the maximum residue limit (MRL) were further analyzed using High-Performance Liquid Chromatography.

Results Quinolone residues were detected in 88.3% of chicken meat and 80% of egg samples. Three chicken meat samples from Kathmandu exceeded the MRL (> 100ppb), with Enrofloxacin found in commercial and education sectors and both Enrofloxacin and Ciprofloxacin in the health sector. In eggs, residue prevalence was 83.9% in Kathmandu followed by Bhaktapur (76.9%) and Lalitpur (65%). Household eggs had the most residues (100%), and the education sector had the least (66.7%) (p = 0.0219). These findings indicate widespread and unregulated quinolone use in poultry production, highlighting the urgent need for prudent antibiotic stewardship to reduce antimicrobial resistance and associated health risks.

 

Keywords Antimicrobial residue, Enrofloxacin, Ciprofloxacin, Quinolones, Maximum residue limit

Citation: Shrestha N, Layalu S, Amatya S, Shrestha S, Basnet S, Pradhan D, Shrestha UT. Quinolones residue in poultry meat and eggs; an alarming public health issue in Nepal. BMC Res Notes. 2026 Jan 6;19(1):49. doi: 10.1186/s13104-025-07627-z. PMID: 41495852; PMCID: PMC12870818.

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