Evaluation of Antibiotic Resistance Patterns and Biofilm Formation among the Clinical Isolates of Pseudomonas aeruginosa

 Asuma Gurung^{1 ߙ}, Samjhana Gurung^{1 ߙ}, Umesh Kaji Manandhar¹, Raina Chaudhary², Anand Kumar Mandal³ Avinash Chaudhary¹, Dinesh Dhakal¹, Anup Muni Bajracharya⁴, Upendra Thapa Shrestha⁵ *

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

² Shree Birendra Hospital Chhauni, Kathmandu, Nepal

³ Department of Pathology, Bhaktapur Hospital, Bhaktapur, Nepal

⁴ Balkumari College, Chitwan, Nepal

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

 

† These authors contributed equally.

 

*Corresponding author: Upendra Thapa Shrestha, Assistant Professor, Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal, E-mail: upendra.thapashrestha@cdmi.tu.edu.np

ABSTRACT

Objectives: To evaluate the antibiotic resistance pattern of Pseudomonas aeruginosa isolated from clinical specimen and to detect Metallo beta lactamase producers as well as to accesses their biofilm forming capacity by both qualitative and quantitative analysis.  

Methods: The study was conducted in Shree Birendra Hospital, Chhauni, from June to August 2025. The total of 6444 specimens was cultured and isolates of P. aeruginosa were subjected to antibiotic susceptibility tests. Metallo beta lactamase producers were identified by modified Hodge and EDTA synergy tests. Biofilm was detected by the Congo Red Agar and Microtiter Plate Assay method.

Results: Out of 671 positive isolates (15.05%) from pus, urine and wound, 101 isolates of P. aeruginosa were obtained. The highest rate of distribution was observed in in-patients as well as in the age group of 61-70 years. Among the isolates, high resistance was observed against Aztreonam (65.59%) whereas isolates were most sensitive against Tobramycin (76%). 37 were found to produce Metallo beta lactamase enzyme and almost 46% were MDR. The biofilm isolates accounted for 34 by CRA but MPA detected 100 biofilm producers. The biofilm producers showed high resistance against Aztreonam (59.41%) and Levofloxacin (56.44%). Furthermore, the MBLS were the most resistant against Levofloxacin (28.7%) followed by Aztreonam (27.7%), Cefepime (27.7%), Ceftazidime (25.7%), Imipenem (25.7%) and Meropenem (25.7%). Out of all the isolates, 36 biofilm isolates were highlighted to produce MBL enzyme as well.

 Conclusion: Pseudomonas aeruginosa was most frequent in sputum and pus samples from inpatients and older patients, with rising resistance to monobactams, fourth-generation cephalosporins, and fluoroquinolones. High rates of MBL production and biofilm formation contributed to marked β-lactam resistance, emphasizing the need for alternative therapeutic strategies.

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Keywords: Pseudomonas aeruginosa, Metallo beta lactamase, Microtitre plate, Biofilm

Antibiotic resistance and β-lactam resistant genes among bacterial isolates from clinical, river water and poultry samples from Kathmandu, Nepal

  

 JAC Antimicrob Resist https://doi.org/10.1093/jacamr/dlaf186 JAC-Antimicrobial Resistance

 

Antibiotic resistance and β-lactam resistant genes among bacterial isolates from clinical, river water and poultry samples from Kathmandu, Nepal

 

Upendra Thapa Shrestha¹, Manash Shrestha², Nabaraj Shrestha³, Komal Raj Rijal¹ and Megha Raj Banjara^1*

 

¹Central Department of Microbiology, Institute of Science and Technology, Tribhuvan University, Kirtipur, Kathmandu, Nepal;

²Asia Pacific Malaria Elimination Network (APMEN), Singapore;

³Central Veterinary Laboratory (CVL), Tripureshwor, Kathmandu, Nepal

 

*Corresponding author. E-mail: megha.banjara@cdmi.tu.edu.np

 

Received 17 August 2025; accepted 25 September 2025

 

Objective: To assess the antibiotic resistance and beta-lactam resistance genes among bacterial isolates from clinical, river water and poultry samples.

Methods: Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were isolated from clinical, poultry and river water samples collected during 2020–22. They were subjected to antimicrobial susceptibility tests following the CLSI guidelines. The bacteria were screened for β-lactam resistance genes blaTEM, mcr-1, mecA and blaNDM-1.

Results: Among 2835 clinical samples, E. coli was the most frequently isolated bacterium (10.3%, 292), followed by S. aureus (6.0%, 169) and P. aeruginosa (4.0%, 143). Of the E. coli isolates, 64.4% exhibited multidrug resistance (MDR) and 43.8% were extended-spectrum β-lactamase (ESBL) producers, with 44.5% and 16.4% harbouring the blaTEM and mcr-1 genes, respectively. Among S. aureus isolates, 80.9% of methicillin-resistant strains (MRSA) carried the mecA gene, while 30.1% of metallo-β-lactamase (MBL)-producing P. aeruginosa were positive for the blaNDM-1 gene. In poultry samples, 30.4% of E. coli isolates harboured the blaTEM gene among 128 ESBL producers, and the prevalence of colistin-resistant isolates carrying mcr-1 was higher than in clinical samples. In contrast, the occurrence of ESBL-producing E. coli and MRSA, along with their associated resistance genes, was lower in water samples.

Conclusions: This study demonstrated widespread multidrug resistance (MDR) and ESBL production among clinical, poultry and river water bacterial isolates in the Kathmandu valley. Colistin-resistant E. coli carrying the mcr-1 gene, methicillin-resistant S. aureus (MRSA) with mecA and metallo-β-lactamase (MBL)-producing P. aeruginosa harboring blaNDM-1 were detected across sources. These findings emphasize an urgent One Health approach to curb the growing threat of antimicrobial resistance in the region.

Citation: Thapa Shrestha U, Shrestha M, Shrestha N, Rijal KR, Banjara MR. Antibiotic resistance and β-lactam resistant genes among bacterial isolates from clinical, river water and poultry samples from Kathmandu, Nepal. JAC Antimicrob Resist. 2025 Oct 17;7(5):dlaf186. doi: 10.1093/jacamr/dlaf186. PMID: 41113068; PMCID: PMC12531798.

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Antibiogram Profile of Respiratory Pathogens and Identifying Predisposing Factors of Respiratory Tract Infections among Patients Visiting Bhaktapur Hospital

Antibiogram Profile of Respiratory Pathogens and Identifying Predisposing Factors of Respiratory Tract Infections among Patients Visiting Bhaktapur Hospital

Shreemila Bajracharya1†, Jharana Thapa1†, Pushpa Thapa Magar1†, Ananda Kumar Mandal2, Niraj Manandhar2, Avinash Chaudhary1, Dinesh Dhakal1, Upendra Thapa Shrestha3*

 

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

²Bhaktapur Hospital, Bhaktapur, Nepal

³Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal

 

†These authors contributed equally.

 

*Corresponding author: Upendra Thapa Shrestha, Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal, E-mail: upendrats@gmail.com

 

ABSTRACT

 

Objectives: To address the current problem of MDR infections and respiratory bacterial pathogens and identify the risk factors associated with respiratory tract infections (RTIs).

Methods: A total of 327 RTI specimens were cultured using a conventional microbiological method to identify potential bacterial pathogens. The isolates were then subjected to antibiotic susceptibility testing using modified Kirby Bauer’s disc diffusion method. In addition, the risk factors associated with RTIs were obtained by direct interviews with patients using a structured questionnaire.

Results: The overall prevalence of RTIs among the study population was found to be 11.9%. The highest rate of infections was observed among patients of age group 61-70 years in both sexes and from ICU wards. Among the bacterial pathogens, Acinetobacter baumannii was isolated in the highest number followed by Pseudomonas aeruginosa. 64.2% A. baumannii isolates were resistant to Azithromycin but 100% sensitive to meropenem. P. aeruginosa resistance rate was 50% to Piperacillin-tazobactam, ciprofloxacin, Polymyxin B and Ceftriaxone, and had the highest MDR. Half of the Staphylococcus aureus isolates were MRSA. Risk factors such as previous infections, family history with RTIs, chronic use of antibiotics, and smoking were found to be significantly associated with RTIs.

Conclusion: We observed high MDR among the respiratory pathogens with growing resistance to β-lactam, macrolides, and Polymyxins whch necessitates alternative drugs in management. There is also need for targeted preventive strategies, prohibition of irrational use of antibiotics, and avoidance of exposure to risk factors such as smoking, outdoor air pollution, and chronic use of antibiotics.

 

Keywords: Respiratory tract infections, MDR, risk factors, Nepal

Citation: Bajracharya S, Thapa J, Thapa Magar P, Mandal AK, Manandhar N, Chaudhary A, Dhakal D, Thapa Shrestha U. Antibiogram profile of respiratory pathogens and identifying the predisposing factors of respiratory tract infections among the patients visiting Bhaktapur Hospital. TUJM, 2024; 11(1): 119-129.

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