Tribhuvan University Journal of Microbiology
The Tribhuvan University Journal of Microbiology is published by the Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu, Nepal. Full text content available here and on the journal's own website www.microbiotu.edu.np
Central Department of Microbiology, Tribhuvan University
© Copyright Central Department of Microbiology, Tribhuvan University
Antibacterial Activity of Bacteriocin Like Compound Extracted from Lactic Acid Bacteria Isolated from Farm Soil, Curd, and Gundruk
Objectives: This study was focused on examining the antimicrobial properties of bacteriocin like compound extracted from Lactic acid bacteria (LAB) isolates from curd, farm soil, and Gundruk samples. Methods: A total of 30 samples of farm soil (10), curd (10) and Gundruk (10) were collected from a Kathmandu district and identified strains of LAB. Dot plate technique was used for screening of bacteriocin, then bacteriocin was extracted from precipitation method. Antimicrobial activity was done from cell-free suspension by Agar well diffusion method. Results: In this study, 86% of LAB were isolated and identified as Streptococcus species (46.67%), Lactobacillus species (23.33%) and Pediococcus species (16.67%). Out of the 26 isolates, 7 isolates (23.33%) produced bacteriocin. The antibacterial activity demonstrated inhibition zones ranging from 7–16 mm for farm soil isolates, 10–20 mm for curd isolates, and 7–18 mm for Gundruk isolates. From mixed extraction of bacteriocin (1:1 of Pediococcus spp. and Streptococcus spp.), antibacterial activity was shown to all test bacteria except S. aureus ATCC 43300. Conclusion: This study concluded that LAB isolates from Gundruk exhibited the highest antibacterial activity (18–21 mm), compared to farm soil and curd isolates, highlighting their potential as a more effective natural antimicrobial source.
Water Quality Assessment: Physicochemical Properties and Microbial Characteristics of Water Across Different Sources
Objectives: To assess the quality of drinking water microbiologically as well as to monitor various physicochemical quality parameters. Methods: The study was a laboratory-based cross-sectional study. Thirty samples of water were taken without contamination from different sources such as stone spouts, boring wells, pumps, dug wells, tap water and jar water. The samples were transported with a cold chain maintained and analyzed promptly. Physicochemical parameters were identified using methods indicated in APHA (2005). Spread plate technique and membrane filtration technique were conducted for total bacterial load count and total coliform load count respectively. Bacterial pathogens were isolated and identified through selective enrichment and culture on specific media as well as using biochemical characterstics. Kirby-Bauer disk diffusion technique was used to determine the antibiotic susceptibility pattern of the isolates which revealed varying rates of resistance among the isolates with some of them having multi-drug resistance. Results: The findings indicated that the highest bacteria loads were on pump (1.43 ×106 cfu/ml) and stone spout water (1.02 ×106cfu/ml), whereas, jar water was not contaminated. In stone spout water counts of coliform were recorded at (70 cfu /ml). Conclusion: The most frequently isolated pathogens were E. coli and Klebsiella spp. Isolates showed resistance to amoxicillin which could mean there are threats to health and therefore better monitoring and treatments of water quality should be considered.
Detection of Antimicrobial Activities and Bacteriocin Encoding Genes in Lactic Acid Bacteria Isolated from Fermented Foods in Kirtipur
Objectives: The objective of this study was to isolate and identify Lactic Acid Bacteria (LAB) from fermented foods and evaluate their antimicrobial activities as well as to detect bacteriocin encoding gene and also determine probiotic effect of selective LAB isolates. Methods: A total of 26 fermented food samples were collected from different small scale dairy shops and community of Kirtipur, Kathmandu and LAB were isolated following standard plate count method. Preliminary identification of isolates was done by staining and biochemical tests. The gene encoding specific bacteriocin were detected using polymerase chain reaction. Results: Based on the morphological, microscopy and biochemical characteristics, a total of 40 LAB were screened; among them 25 (62.5%) were Gram-positive rod shape LAB A (Lactobacillus spp) type and 15 (37.5%) isolates were gram-positive cocci shape LAB B type. Among 40 isolates of Lactic Acid Bacteria, cell free supernatant of 24 (60%) showed antibacterial activity with highest being that of isolates Ca3 and Ca4 LAB against all 6 test bacteria. Isolated LAB were most effective against Pseudomonas aeruginosa i.e. out of 24 LAB 20 (83.33%) isolates showed inhibition zone. Enterocin gene were detected in 4 (16.66%) LAB isolates while nisin and pediocin gene were not detected in isolated LAB. All 9 selected LAB isolates were able to resist high acidic condition at pH 3 till 24 hrs, 0.5% and 1% bile salt concentration while isolates C3 (Enterococcus spp) and Ca3 (Lactobacillus spp) were able to resist pH 3 till 48 hof incubation. Therefore, they can survive in stomach high acidic and bile condition indicating their probiotic potentiality. Conclusion: These findings emphasize LAB's potential as natural antibacterial agents that could be exploited in food preservation and as probiotics to improve human health.
Microbiological Assessment of Selected Vegetables from Kathmandu, Nepal
Objectives: To determine the microbial load and antibiotic susceptibility of bacterial isolates from selected vegetables in Kathmandu. Method: This study was conducted in the department of microbiology, Tri-Chandra multiple campus from March to July 2025. A total of 30 samples including, moringa, cucumber, spinach, chili, peas, cauliflower, okra, carrot, cabbage, and brinjal, were collected in sterile containers from markets, hotels, and farms and were transported to the laboratory under cold chain. The samples were cultured on Plate Count Agar (PCA), Potato Dextrose Agar (PDA), and Violet Red Bile Agar (VRBA). The PCA and VRBA plates were incubated at 37℃ for 24 hours and PDA plates at 28℃ for 24-48 hours. Bacterial isolates were identified using Gram staining and various biochemical tests, and antibiotic susceptibility was performed. Fungal presence was detected by using Lactophenol Cotton Blue stain and parasites were identified by Wet Mount method. Results: Spinach from vendor had the highest mesophilic bacterial load (1.54×10⁶CFU/g) and lowest on peas from hotels (1.7×103CFU/g). Coliform were highest in vendor cabbage (2.89×10⁵CFU/g), while peas consistently showed lowest counts (5×102CFU/g) from all sources. Bacteria such as Pseudomonas spp., E. coli, Proteus spp., Enterobacter spp, S. aureus, Klebsiella spp, and fungi like Aspergillus spp, Fusarium spp, Alternaria spp, Cladosporium spp, Candida spp, and parasites G. lamblia, E. histolytica, Ascaris were identified. Most of the bacterial isolates were resistant to the antibiotics used, including Ceftriaxone, Cotrimoxazole, Ceftazidime, Amikacin, Erythromycin, and Ciprofloxacin with only few exhibiting susceptibility. Conclusion: The study revealed a significant presence of pathogens and antibiotic resistant strains highlighting the importance of improved food safety practices, regular microbial monitoring, and public awareness to reduce the risk of foodborne diseases in urban Nepal.
Bacterial Profiling of Fish in Kathmandu Valley Market
Objectives: The purpose of the study was to identify the bacterial species in fishes as well as to enumerate the total viable count and total coliform count in the fish sample from Kathmandu valley market. Methods: A descriptive study was conducted where two species of fish i.e., Rohu and Bachua, were collected from several shops within the Kathmandu valley. Each fish was separated into gills, gut, and skin portions, constituting a total of 18 samples and the samples were then processed according to standard laboratory methods for the isolation and identification of bacteriological species. Results: In a total sample size of 18 samples, 44 isolates were isolated where 20.46% of the isolates were found to be gram-positive bacteria and 79.54% of the isolates were found to be gram-negative bacteria. Escherichia coli accounted for 38.64%, resulting in being the dominant organism. The sample collected from Kalimati in Bachuwa showed the highest bacterial count (1.01×107cfu/gm) while the sample from Lalitpur in Rohu showed the lowest bacterial load (9.68×104cfu/gm). In Rohu samples, the highest coliform load and lowest coliform load was collected from Kalimati (4.25×105cfu/gm) and Lalitpur (3.78×103cfu/gm), respectively. Conclusion: The highest bacterial load, coliform load and isolated pathogens in fishes available in the market of Kathmandu valley from this study concluded that the fishes are highly vulnerable to bacterial contamination, and suggest the potential risk for public’s health issues.
Copyright (c) 2025 Central Department of Microbiology, Tribhuvan University
Isolation and Characterization of Bacillus spp with Potent Proteolytic and Antipathogenic Activities
Objectives: The current study aimed to determine the proteolytic and antipathogenic activity of Bacillus spp isolated from soil samples collected across various ecological and land-use categories in multiple locations within the Kathmandu Valley. Methods: A cross-sectional study was conducted at the Med-Micro Nepal Community Development and Research Centre, Kathmandu. Seventeen different soil samples were collected and processed to isolate Bacillus species. The isolates were identified as Bacillus spp on the basis of their morphological characteristics, Gram's staining, spore staining and biochemical tests based on Bergey's Manual of Systematics of Archaea and Bacteria. The proteolytic activity was screened and determined by well diffusion method on 1% gelatin agar media for both crude and purified form of enzyme. Similarly, antipathogenic assay was done on Mueller Hinton agar by agar well diffusion method. Results: All 17 Bacillus isolates exhibited proteolytic activity, with enhanced activity observed upon partial purification. Notably, isolate AM showed the highest increase (25%) in protease activity, while RS and RH displayed the largest overall proteolytic zones (32 mm and 31 mm, respectively). Isolates RH, RK, FM, FN, and FS demonstrated both strong antipathogenic and proteolytic activities, suggesting a potential correlation between protease production and antimicrobial efficacy. Conclusion: These findings highlight the therapeutic potential of selected proteolytic Bacillus strains, particularly against Streptococcus spp and E. coli.
Bacteriological Profile and Antibiotic Subsceptiblity Patterns of Asymptomatic UTI among Female Students of R.R.M Campus Janakpurdham, Madhesh Pradesh, Nepal
Objective: The primary goal of this study was to identify common pathogenic microorganisms and their patterns of antibiotic susceptibility from asymptomatic UTI cases. Methods: A Total of 151 mid-stream urine samples were collected from female students for bacteriological identification and antimicrobial susceptibility testing. Conventional biochemical tests identified the isolates, and their antibiotic susceptibility was determined according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Results: Of the 151 samples analyzed, 30.46% exhibited significant bacterial growth, with Staphylococcus aureus being the most prevalent (30.43%), followed by Escherichia coli (17.39%) and Klebsiella pneumoniae (10.86%). Gram-negative bacterial isolates showed a higher level of resistance to amoxicillin (33%-100%), amoxicillin (60%-100%), amoxicillin-clavunic acid (20%-100%), ceftriaxone (60%-100%), cotrimoxazole (40%-100%), nitrofurantoin (40%-100%), and ciprofloxacin (40%-100%). Piperacillin and Tazobactam, levofloxacin, imipenem, and amikacin were less resistant. Gram-positive bacterial uropathogens showed a high level of resistance to amoxicillin (65%-100%), ciprofloxacin (50%-100%), levofloxacin (50%-100%), and clindamycin (64%-100%). Imipenem, gentamicin, piperacillin, and tazobactam have shown reduced resistance. Conclusion: Uropathogens were found to be highly prevalent, and bacterial isolates were shown to be highly resistant to routinely recommended medications. In order to prevent an asymptomatic infection from developing into a symptomatic UTI, routine UTI screening, regular health education on the risk of asymptomatic infectious diseases for females in the reproductive age group, and antibiotic susceptibility testing should be implemented.
Airborne Bacteria and Fungi in the Urban Area of Kathmandu
Objectives: The study was conducted to enumerate and identify the airborne bacteria and fungi in the urban area of Kathmandu using the settle plate method and to determine the antibiotic susceptibility pattern of the identified bacteria. Methods: The cross-sectional study was done from March to May 2025. A total of 39 air samples were collected from 3 distinct sites: Asan, Kamaladi Ganesh Mandir, and Tri-Chandra Multiple Campus, with 13 samples from each site, using the gravity settle plate method in Nutrient Agar and Potato dextrose agar media at 37°C for 24 hours for bacteria and 28°C for 3-5 days for fungi and the research was carried out at the Department of Microbiology, Tri-Chandra Multiple Campus. Results: The bacterial load ranged from 640 to 4x104 CFU/m3, while fungal load ranged from 8.4x102 to 4.9x103 CFU/m3. The dominant bacterial isolates were Micrococcus spp. (25.17%), followed by Bacillus spp. (21.79%), S. aureus (19.05%), E. coli (18.37%), and Klebsiella spp. (15.65%), whereas Aspergillus spp. (21.4%) was the most dominant fungi followed by Fusarium spp. (18.25%), Penicillium spp. (15.9%), Cladosporium spp. (15.1%), Mucor spp. (14.3%), Rhizopus spp. (8.7%), and Alternaria spp. (6.4%). Conclusion: The present study shows that air contains various bacteria and fungi, which can be harmful to human health. It highlights the need to reduce air pollution and raise public awareness.
Exploring Bacillus spp Protease Activity in Slaughterhouse Soils
Objective: To correlate protease-producing Bacillus spp with physicochemical parameters from slaughterhouse soils. Methods: In this study, eight soil samples were collected from three slaughterhouses located in the Kathmandu Valley and designated as K1, 2, L1-3, and B1-3. Sterile methods were employed to collect the samples, and their physicochemical properties, including temperature, pH, moisture, electrical conductivity, alkalinity, and nutrients, were analyzed. This was followed by enrichment and isolation of protease-producing Bacillus spp. Results: The collected soils were pale to neutral grey and had alkaline pH. The soils contained moderate water, up to 14%. Even with low organic matter, it had high nitrogen levels. This study isolated Bacillus spp that produce proteases and measured the specific protease activity. Conclusion: Protease-producing Bacillus found in soils are directly proportional to the nutrients, especially in soils with higher nitrogen levels, which tend to have a greater abundance of protease bacteria. This indicates that soil fertility influences bacterial protease functions.
Evaluation of Antibiotic Resistance Patterns and Biofilm Formation among the Clinical Isolates of Pseudomonas aeruginosa
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.
Determination of Antibacterial Efficacy of Different Soaps Found in the Local Market against Common Pathogenic Bacteria
Objective: This study aimed to evaluate the antibacterial efficacy of different type of soaps against Staphylococcus aureus, Escherichia coli and Bacillus species. Methods: A laboratory-based experimental study was conducted from February 2024 to July 2024. Eight commonly used soaps (Herbal, Non-medicated, Medicated, Liquid and Laundry) were randomly collected from the local market of Kathmandu valley. The bacterial cultures used for test were standardized to 0.5McFarland. The soap solutions were prepared by dissolving each soap in sterile distilled water (100mg/ml), and two-fold dilution made for MIC testing. Antibacterial activity was assessed by Agar Well Diffusion method using Mueller-Hinton Agar. Wells were filled with 1ml of each prepared soap solution and incubated at 37°C for 24 hours. Zones of Inhibition were measured, and MIC was determined as the lowest dilution showing no visible growth. Results: Non-medicated soaps showed mean ZOI of 16.7mm (NM1 brand being effective with mean ZOI of 21 mm) and medicated soap showed mean ZOI of 16.1mm. Handwash showed ZOI range between 16-19mm with mean of 17.3mm. Herbal soap has a strong 17mm of mean ZOI with range of 8-23mm. The brand NM1 soap showed most effective against E. coli (20mm) and least against S. aureus (15mm) with MIC value 1.56mg/ml. Herbal soap showed maximum effect against E. coli (20mm) with MIC value 6.25mg/ml and of 3.125mg/ml against S. aureus. Other soaps showed MIC in the range from 3.125mg/ml to 50mg/ml. Conclusion: Non-medicated soap showed the strongest antibacterial activity against Bacillus and E. coli, while Herbal soap was most effective against S. aureus. Difference in efficacy among soaps are attributed to variation in their antimicrobial compound. The finding challenges the idea that medicated soaps are always more effective than non-medicated ones. Soap formulation should prioritize proven antimicrobial efficacy while remaining affordable for widespread use.
Antibiofilm Activity of Bacteriophage Isolated from Sewage-Polluted Water against Escherichia coli
Objectives: This study aimed to explore bacteriophages, viruses that infect bacteria, as an alternative antibiofilm agent. Method: 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.
Assessment of Antibiotic Resistance of Escherichia coli Isolated from Poultry Droppings in the Kathmandu Valley
Objective: To assess antibiotic resistance in Escherichia coli isolated from chicken droppings from selected poultry farms within Kathmandu valley. Methods: Stool samples of chicken from 21 different farms were collected aseptically and transported to Central Department of Microbiology laboratory. Samples were cultured in MacConkey and M-Endo agar to isolate E. coli and was confirmed phenotypically using biochemical tests. The isolates were tested for antimicrobial susceptibility by modified Kirby-Bauer disk diffusion method following CLSI guidelines. Results: E. coli were isolated from all 104 dropping samples. E. coli isolates were resistant to ampicillin/sulbactam (91.34%), cefoxitin (98.07%), chloramphenicol (77.88%), ciprofloxacin (83.65%), contrimoxazole (79.81%), gentamicin (65.38%), levofloxacin (83.65%), and tetracycline (100%). While less proportions of E. coli were resistant to ceftriaxone (16.35%), colistin (3.85%) and imipenem (25%). Out of 104 isolates, 94 (90.38%) were multidrug resistant (MDR). Frequency of cleaning of the coop (p = 0.0017), farm size (p <0.001), farm operation (p<0.001), water source (p < 0.001) and common diseases of poultry (p < 0.001) were found significantly associated with MDR E. coli. Conclusion: High prevalence of MDR E. coli was found on chicken within Kathmandu valley, which might be introduced into humans through food chain. Therefore, adherence of biosecurity measures for reducing the use of antibiotics in the poultry farms is suggested.
Molecular Detection of CTX-M Type ESBL Genes in Clinical Isolates of Klebsiella Species
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.
An Integrative Analysis of Community-Level Determinants of Pediatric Diarrhea in Peri-Urban area of Kathmandu
Objectives: This study aimed to identify community-level environmental and behavioral determinants associated with acute pediatric diarrhea in three peri-urban coverage hospitals in Kathmandu. Methods: This cross-sectional community-based study was carried out in three peri-urban Kathmandu hospitals starting in May 2024 and recruited 550 children under five years of age presenting with diarrheal symptoms following guardian consent, utilizing semi-structured questionnaires for data collection. Results: Abdominal cramps (66.7%) and mucus in stool (64.2%) were the most prevalent symptoms whereas blood in stool (8.5%) and blood in urine (1.6%) were least common. Statistical analysis revealed that the predominant source of drinking water (Jar Water, 65.8%) was strongly associated with both vomiting and watery stool (both χ², p < 0.001). Multivariate logistic regression identified age (adjusted OR = 1.32, 95% CI = 1.15–1.52) and putting toys in the mouth (adjusted OR = 2.02, 95% CI = 1.29–3.15) as significant, independent predictors of fever (p ≤ .002). While the fever model showed 69.8% classification accuracy, its overall fit was borderline poor (Hosmer-Lemeshow p = 0.045). ROC analysis confirmed age as the best single predictor, while stool consistency and mucus in stool had poor individual discriminatory power. Conclusions: These findings underscore the necessity of targeted public health interventions focusing on child-specific hygiene practices and the safety of household drinking water sources in this rapidly urbanizing context.
Comparative Study of Surgical Site Infections and Antimicrobial Resistance with Focus on Carbapenem Resistant Klebsiella pneumoniae
Objectives: The aim of this study evaluates the trends in surgical site infections (SSIs), bacterial distribution, antimicrobial resistance, and molecular detection of resistance genes in two different phases. Methods: The clinical specimens were collected from SSIs patients in both phases. The bacteria was isolated using standard microbiological techniques and further identified by the VITEK 2 system. Phenotypic screening for carbapenemase was conducted through Modified carbapenem inactivation method (mCIM) while presence of blaKPC, acrA, and acrB genes were detected by PCR. Results: In phase two, the SSIs rate reduced by 33% particularly due to improvement in prophylactic practices. The number of isolated bacteria decreased by 73.13%, with Gram-negative bacteria remaining predominant. The study reported significant increase in resistance in Klebsiella pneumoniae particularly to amikacin (100%), colistin (80%), and tigecycline (20%) whereas found 100% susceptible to doripenem. All carbapenem resistant K. pneumoniae were found mCIM positive but blaKPC negative, while acrA and acrB genes were detected in all the isolates. Conclusion: Implementation of improved antimicrobial prophylaxis guidelines resulted in a significant reduction in infection rates. However, an increase in antimicrobial resistance among K. pneumoniae was observed. Although the blaKPC gene was not detected in carbapenem-resistant isolates, the presence of efflux pump genes in all resistant strains suggests their contributory role in resistance. These findings underscore the urgent need for strengthened antibiotic stewardship and continuous surveillance of resistance mechanisms to curb antimicrobial resistance in surgical settings.
The One Health Approach: A Critical Pathway for Public Health and Sustainable Development in the Developing World
One Health, which views interdependencies between human, animal, and environmental health, is receiving increasing attention across the globe as an effective way to handle the complexities associated with health issues. In developing countries, like Nepal, where the economic survival of human populations is ecologically interwoven with animals, wild animals, and the natural environment, One Health is no longer a theoretical or academic model but the need of the day. Nepal is an exemplary situation for applying the concepts of One Health. There is a large number of people that depend on agriculture and animal resources as a means of living. Direct contact between human and animal populations and minimal biosecurity measures make them vulnerable to incidents of transmitting and acquiring diseases from each other. These include rabies, bird flu, brucellosis, leptospirosis, Q fever, tick-borne viral diseases, and Japanese encephalitis, which continue to threaten the community at large. Furthermore, these diseases continue to have an increased impact on the rural sectors and the commonly deprived sections of the community, thereby worsening the already prevailing disparity between those who are able to access better healthcare and those who are deprived.
Assessment of Oxygen Demand and Antibiotic Resistant Citrobacter spp. in the Bagmati River
Objectives: To correlate the Oxygen demand with antibiotic resistant Citrobacter species in Bagmati river. Methods: A Cross-sectional study was conducted from May to August 2025 at the Department of Microbiology, Tri-Chandra Multiple Campus, Kathmandu. Fifteen water samples collected in duplicate were examined for biological oxygen demand (BOD), dissolved oxygen (DO), most probable number (MPN) counts and presence of antibiotic resistant Citrobacter species. The correlation analysis was conducted using Exploratory software version 6.10.3.1. Results: The MPN count of total coliforms was lowest at the upstream site (4 MPN/100 mL), and peaked downstream (35,000 MPN/100 mL). This was accompanied by a decline in DO (8.7, 4.2, and 1.2 mg/L) and an increase in BOD (0.1, 250.8, and 425.4 mg/L). Citrobacter appeared as pink, non-metallic colonies on EMB agar, and 394 isolates were confirmed biochemically. Among these, 100% were resistant to ampicillin (penicillin) and 99 % (390/394) toward erythromycin (macrolide), while resistance to cefotaxime (68%), amikacin (53%,aminoglycoside), ciprofloxacin (49%, fluoroquinolone), and chloramphenicol (44%, phenicol) was also recorded. Positive correlation (r = 0.835, p< 0.05) was observed for presence of Citrobacter and BOD and whereas negative correlation (r= -0.85, p<0.05) was observed for presence of Citrobacter and level of DO. Conclusion: The increase in BOD and decrease of DO in the downstream region and its correlation with the presence of antibiotic resistant Citrobacter species signifies polluted water as contributor to antibiotic resistant coliform.
Biofilm Forming Antibiotic Resistant Enteric Bacteria from Drinking Jar Water in Kathmandu Valley, Nepal
Objectives: To determine bacteriological quality of drinking jar water from Kathmandu valley, Nepal and detect biofilm forming antibiotic resistant enteric bacteria. Methods: A cross-sectional study was conducted during February-March 2023. Drinking jar water samples (n=36) were collected from Kathmandu valley. Isolation and enumeration of coliform were done by membrane filtration method. Bacterial isolates were characterized by biotyping, antibiotic susceptibility pattern was assessed and biofilm formation was detected by tube adhesion method. Results: Bacteriological analysis revealed the contamination of 97.2% of water samples with total coliform and 11.1% of water samples with thermotolerant coliform. Among 78 bacterial isolates, Klebsiella spp. (32.1%) was the most common bacteria followed by Escherichia coli (15.4%). Most of E. coli and Klebsiella spp. isolates were resistant to antibiotics. Multiple antibiotic resistant (MAR) Klebsiella spp. and thermotolerant Klebsiella spp. were detected. Biofilm forming E. coli (38.5%) and Klebsiella spp. (37.9%) were more resistant to antibiotics tested. Conclusion: The higher number of drinking jar water in Kathmandu valley were contaminated with coliform and presence of biofilm forming antibiotic resistant enteric bacteria in water showed a high risk of waterborne infections to consumers. Quality control of drinking jar water is essential to improve water quality and prevent waterborne diseases.
Bioactive Potential of Guava Leaves against Bacterial Pathogens
Objectives: The study was conducted to analyze antimicrobial activities of leaf extract of Guava against Gram positive and Gram negative bacteria. Method: The leaf samples of Guava were collected from different parts of Lalitpur district and were processed to analyze the antimicrobial property of different solvent extract of guava leaf by using Agar well diffusion method. Results: The results of the study indicated that three out of three of the crude solvent extract prepared from the leaves of guava, Methanol, Ethanol and Distilled water showed inhibitory activity against bacteria. Only Gram-positive bacteria, Staphylococcus aureus were susceptible to the all the extract, while Escherichia coli did not show any inhibitory action. Among the four sample extract of guava leaf from different solvent, the distilled water showed highest zone of inhibition by 25mm, followed by methanol extract with 20mm zone of inhibition and ethanol extract by 19mm zone of inhibition. At 10mg/50µL, the distilled water extract showed more antimicrobial activity with mean zones of inhibition 23.66mm than Methanol and Ethanol extracts with mean zone of inhibition 18mm and 16.33mm respectively. Conclusion: Leaf extract of Guava showed the antibacterial activity against Staphylococcus aureus.
Analysis of Bacteriological Quality and Antibiogram of Escherichia coli and Staphylococcus aureus in Raw Milk Sold in Janakpurdham
Objectives: To assess the microbiological quality of raw milk sold in Janakpurdham, Nepal, by determining the Total Viable Count (TVC) and Total Coliform Count (TCC), isolating Escherichia coli and Staphylococcus aureus, and evaluating its antibiotic susceptibility pattern. Methods: A total of 74 raw milk samples were aseptically collected from dairies and farmers in Janakpurdham from March to June 2025. TVC was determined using the pour plate method on Nutrient Agar, and TCC/E. coli isolation on Eosin Methylene Blue Agar. S. aureus isolation was done on mannitol salt agar after enrichment. Conventional biochemical tests were used to confirm the isolates. Antimicrobial susceptibility of the isolates was performed using the Kirby-Bauer disk diffusion method. Results: Mean TVC was 1.13 × 10⁹ CFU/ml (range: 2.075 × 10⁸–2.76 × 10⁹), and mean TCC was 7.40 × 10⁷ CFU/ml (range: 2.0 × 10⁵–5.28 × 10⁸). E. coli was isolated from all seventy-four samples. Susceptibility was highest to gentamicin (100%) and chloramphenicol (85.13%), but 100% resistance was observed to ampicillin and amoxicillin-clavulanate. 60.81% isolates were multidrug-resistant. S. aureus was detected in 48 samples (65%). Antibiotic susceptibility testing revealed 100% resistance to ampicillin and 72.9% to cefoxitin, while varying resistance was observed for linezolid, erythromycin, clindamycin, and others. Conclusion: Raw milk in Janakpurdham exhibits high microbial contamination and antibiotic-resistant bacteria, posing public health risks; therefore, improved hygiene and antibiotic stewardship are essential.