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• Prevalence and Antibiotic Resistance Profile of Colistin-Resistant Escherichia coli Isolated from Chicken Sold at Markets in Gia Lam commune, Ha Noi

  Hoang Minh Duc, Nguyen Thi Lan, Tran Hiep, Hoang Viet Giang, Tran Thi Khanh Hoa, Tran Thi Cam Ly, Cam Thi Thu Ha, Hoang Minh Son

  Date Received: 21-11-2025 / Date Accepted: 27-03-2026 / Date Published: 29-04-2026

   Abstract PDF (VIETNAMESE)

  The study was conducted to determine the prevalence and antibiotic resistance profile of colistin-resistant E. coli isolated from chickens sold at several markets in Gia Lam commune, Ha Noi. A total of 50 rectal swab samples were randomly collected from chickens at 10 markets for the isolation of colistin-resistant E. coli using culture on selective media supplemented with colistin (2 mg/l). The antibiotic resistance profiles of the isolates were investigated using the disk diffusion method and multiplex-PCR was performed to detect colistin-resistant genes (mcr) genes. The results showed that 56% (28/50) of the swab samples were positive for colistin-resistant E. coli. The isolates exhibited high resistance rates to ampicillin and tetracycline (96.43%), trimethoprim/sulfamethoxazole (85.71%), and streptomycin (85.71%). None of isolates were resistant to cefepime, ceftazidime, and meropenem. The results of PCR indicate that all isolates carried the mcr-1 gene. The findings of this study reflect the current status of antibiotic resistance in E. coli, providing a scientific basis for proposing measures to control antibiotic use in poultry production, thereby reducing the risk of transmission to the food chain.

  DOI: https://doi.org/10.31817/tckhnnvn.2026.24.4.05

• Antibiotic Resistance Profile of Colistin-Resistant Escherichia coli Isolated from Raw Pork Sold at Retail Markets

  Cam Thi Thu Ha, Hoang Minh Duc, Hoang Minh Son

  Date Received: 18-06-2025 / Date Accepted: 07-12-2025 / Date Published: 24-12-2025

   Abstract PDF (VIETNAMESE)

  The emergence and widespread dissemination of colistin-resistant E. coli is a significant challenge to both human and animal health. This study aimed to determine the prevalence and antibiotic resistance profile of colistin-resistant E. coli isolated from raw pork sold at traditional markets in Dong Anh, Hanoi. E. coli was isolated using culture on selective media. The antibiotic resistance of E. coli was determined using a microbroth dilution method following the guidelines of the Clinical and Laboratory Standards Institute. The mcr gene was detected by multiplex-PCR. The results of this study showed that 26% (13/50) of the pork samples were positive for colistin-resistant E. coli. High resistance levels were observed for florfenicol, ampicillin, streptomycin, tetracycline, trimethoprim/ sulfamethoxazole, and nalidixic acid, with resistance rates ranging from 84.62% to 100%. All colistin-resistant E. coli isolates were identified as multidrug-resistant strains and carried the mcr-1 gene. These findings highlight that raw pork poses a potential risk for the transmission of colistin-resistant E. coli from meat to humans, thereby increasing the risk of antimicrobial-resistant bacterial infections in the community.

  DOI: https://doi.org/10.31817/tckhnnvn.2025.23.12.03

• Characteristics of Colistin and Other Important Antibiotics Resistance Genes of Escherichia coli Isolated from Pig and Farm-Workers in Soc Son, Ha Noi

  Dang Thi Thanh Son, Tran Thi Nhat, Phan Thi Phuong Thao, Nguyen Thi Thanh Thuy, Etiene Loire, Truong Nhat My

  Date Received: 26-02-2025 / Date Published: 26-02-2025

   Abstract PDF (VIETNAMESE)

  Antibiotic-resistant bacteria and the circulation of drug-resistant genes are a threat to public health globally. Research results show that the rate of detected of colistin ressitant E. coli from pigs in small- scale pig farm in Soc Son - Hanoi was 72% (36/50 farms) and from farm-workers was 16% (8/50 farms). Of these, 10 E. coli strains from 05 farms were selected for analyzing their genomic sequences by Oxford Nanopore Technologies (ONT) systerm (one strain from pig and one strain from farm-worker each of five farms). The studied results showed that 38 resistance genes (14 genes located on chromosome và 31 genes located on plasmids) with 9 antibiotic group. 10 strains were determined to carry to 7-22 resistance genes simultaneously. E. coli strains carried resistance genes of β-lactams, colistin, tetracycline, sulfonamide, quinolon, phenicol, aminoglycoside, marcolide, trimethoprim. The mcr-1 and/or mcr-3 were found in 10 E. coli strains carrying colistin-resistance phenotype. One strain isolated from farmer and 3 strains isolated from pigs carried 2 mcr-1 and mcr-3 simultaneously. One E. coli strain (barcode 60 - PCE 20.1) was detected from pigs and another (barcode 67- PCE 31.1) was isolated from farm-workers were of the same resistance gen characteristic eventhought they were detected from two diffirent farms.

  DOI: https://doi.org/10.1234/z77jv460

• Assessment of Extraction Efficacy and Antibacterial Activity of Ethanol Extract of Caesalpinia sappanL.against Escherichia coli

  Nguyen Ba Tiep, Nguyen Tan Dat

  Date Received: 30-05-2016 / Date Accepted: 16-10-2016 / Date Published: 13-06-2025

   Abstract PDF (VIETNAMESE)

  Maceration extraction of Caesalpinia sappan L. (CS) in ethanol solvent (96%) followedby steam distillation at 80-90oC resulted in an average extract efficacy of 6.80%. Ten percent extract sollution showed inhibitory effects on E. coli. The effectswere concentration-dependent and higher on standard E. colistrain in comparison to those on chicken-derived isolates. The strain dependent inhibition was similarly observed for doxycycline, ciprofloxacin and colistin. The 10% sollution of CS extract exerted preventiveand treatment effects on experimental infection with E. coliin Yellow-featherchickens. The results can be considered asscientific basisfor further studies on prevention and treatment potentialof CS extracts.

  DOI: https://doi.org/10.31817/tckhnnvn.2016.14.9.

• Detection of Salmonella typhimuriumCausing Salmonellosisin Layer Ducks Raised in Phung Thuong Commune, Phuc Tho, Hanoi

  Truong Ha Thai, Chu Thi Thanh Huong, Vu Thi Thu Tra, Cam Thi Thu Ha, Truong Lan Oanh

  Date Received: 15-03-2023 / Date Accepted: 05-01-2024 / Date Published: 12-06-2025

   Abstract PDF (VIETNAMESE)

  The purpose of this study was to identify Salmonella typhimurium (S.typhimurium), causing salmonellosis in layer ducks farmed in Phung Thuong commune, Phuc Tho, Ha Noi. A total of 32 farm households were selected based on farm-scale and breeding method. Forty-four salmonelosis-suspected ducks were necropsied to monitor gross lessions; of which, 33 ducks had gross lessions of the disease. We collected livers (15 samples), spleens(11 samples), and ovary (7 samples) from 33 ducks with gross lession of the disease, besides, irregular egg yolks (15) were collected for bacteria isolation and then typing by PCRmethod. Results indicated that liver samples had the highest percentage of positive samples (60.0%), followed by spleen (54.5%), ovary (42.9%) and the lowest was the irregular egg yolk sample (40.0%). Twenty-four S.typhimurium strains were isolated and detected by PCR method. Testing the antibiotic sensitivity of the S.typhimurium isolates showed that thesestrains were most susceptible to colistin(100%), followed by doxycycline (79.2%) and gentamicin (70.8%) but moderately sensitvie or resistant to amoxicillin, ampicillinand neomycin.

  DOI: https://doi.org/10.31817/tckhnnvn.2024.22.2.

• Antibiotic Resistance and Production of Extended Spectrum β-lactamase (ESBL) of SalmonellaIsolated from Pork and Chicken Meat in Local Markets of Soc Son District, Ha Noi

  Cam Thi Thu Ha, Hoang Minh Duc, Pham Hong Ngan

  Date Received: 10-08-2023 / Date Accepted: 20-11-2023

   Abstract PDF (VIETNAMESE)

  This study was conducted to identify anti-biotic resistance profile and ESBL- encoding genes of the Salmonellaisolates from one hundred meat samples (50 chicken and 50 pork samples) randomly collected in local markets in Soc Son district, Ha Noi. The results showed that Salmonellawere detected in 41.0% samples, of which 42.0% of chicken samples and 40.0% of pork samples were positive for Salmonella. The isolates exhibited highly resistance to tetracycline (97.56%), flofenicol (78.05%) and ampicillin (63.41%), but low resistance to ceftazidime (7.32%), ciprofloxacin (7.32%). However, all isolates were susceptible to meropenem and colistin. Notably, 68.29% of Salmonellaisolates were multi-resitant strains. 6/41 (14.63%) Salmonellaisolates produced ESBL, in which, one isolate carried blaCTX-M-9gene, three isolatescarried blaTEMgene, one isolatecarried blaCTX-M-1and blaCTEM, and one isolatesimultaneously carried blaCTX-M-1, blaCTX-M-8/25, blaCTEMgens.