Evaluation of Biofilm Production and Antibiotic Resistance/Susceptibility Profiles of <i>Pseudomonas</i> spp. Isolated from Milk and Dairy Products

Dairy-borne <i>Pseudomonas</i> spp., known for causing spoilage, may also exhibit antibiotic resistance and form biofilms, enhancing their persistence in dairy environments and contaminating final products. This study examined biofilm formation and antibiotic resistance in 106 <i>P...

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Main Authors: Iván Briega, Sonia Garde, Carmen Sánchez, Eva Rodríguez-Mínguez, Antonia Picon, Marta Ávila
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Foods
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Online Access:https://www.mdpi.com/2304-8158/14/7/1105
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author Iván Briega
Sonia Garde
Carmen Sánchez
Eva Rodríguez-Mínguez
Antonia Picon
Marta Ávila
author_facet Iván Briega
Sonia Garde
Carmen Sánchez
Eva Rodríguez-Mínguez
Antonia Picon
Marta Ávila
author_sort Iván Briega
collection DOAJ
description Dairy-borne <i>Pseudomonas</i> spp., known for causing spoilage, may also exhibit antibiotic resistance and form biofilms, enhancing their persistence in dairy environments and contaminating final products. This study examined biofilm formation and antibiotic resistance in 106 <i>Pseudomonas</i> spp. strains isolated from milk, whey, and spoiled dairy products. Phylogenetic analysis (based on partial <i>ileS</i> sequences) grouped most strains within the <i>P. fluorescens</i> group, clustering into the <i>P. fluorescens</i>, <i>P. gessardii</i>, <i>P. koorensis</i>, and <i>P. fragi</i> subgroups. Biofilm formation in polystyrene microplates was assessed at 6 °C and 25 °C by crystal violet staining. After 48 h, 72% and 65% of <i>Pseudomonas</i> strains formed biofilms at 6 °C and 25 °C, respectively, with higher biomass production at 6 °C. High biofilm producers included most <i>P. fluorescens</i>, <i>P. shahriarae</i>, <i>P. salmasensis</i>, <i>P. atacamensis</i>, <i>P. gessardii</i>, <i>P. koreensis,</i> and <i>P. lundensis</i> strains. The <i>adnA</i> gene, associated with biofilm formation, was detected in 60% of the biofilm producers, but was absent in <i>P. fragi</i>, <i>P. lundensis</i>, <i>P. weihenstephanensis</i>, and <i>P. putida</i>. Antibiotic susceptibility was tested using the disk diffusion method. All strains were susceptible to amikacin and tobramycin; however, 73% of the strains were resistant to aztreonam, 28% to imipenem and doripenem, 19% to ceftazidime, 13% to meropenem, and 7% to cefepime. A multiple antibiotic resistance index (MARI) > 0.2 was found in 30% of the strains, including multidrug-resistant (<i>n</i> = 15) and extensively drug-resistant (<i>n</i> = 3) strains. These findings highlight <i>Pseudomonas</i> spp. as persistent contaminants and antibiotic resistance reservoirs in dairy environments and products, posing public health risks and economic implications for the dairy industry.
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spelling doaj-art-c7c3d0dd7a394ef3830a34c044654e1b2025-08-20T02:15:58ZengMDPI AGFoods2304-81582025-03-01147110510.3390/foods14071105Evaluation of Biofilm Production and Antibiotic Resistance/Susceptibility Profiles of <i>Pseudomonas</i> spp. Isolated from Milk and Dairy ProductsIván Briega0Sonia Garde1Carmen Sánchez2Eva Rodríguez-Mínguez3Antonia Picon4Marta Ávila5Departamento de Tecnología de Alimentos, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), CSIC, Carretera de La Coruña km 7, 28040 Madrid, SpainDepartamento de Tecnología de Alimentos, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), CSIC, Carretera de La Coruña km 7, 28040 Madrid, SpainDepartamento de Tecnología de Alimentos, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), CSIC, Carretera de La Coruña km 7, 28040 Madrid, SpainDepartamento de Tecnología de Alimentos, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), CSIC, Carretera de La Coruña km 7, 28040 Madrid, SpainDepartamento de Tecnología de Alimentos, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), CSIC, Carretera de La Coruña km 7, 28040 Madrid, SpainDepartamento de Tecnología de Alimentos, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), CSIC, Carretera de La Coruña km 7, 28040 Madrid, SpainDairy-borne <i>Pseudomonas</i> spp., known for causing spoilage, may also exhibit antibiotic resistance and form biofilms, enhancing their persistence in dairy environments and contaminating final products. This study examined biofilm formation and antibiotic resistance in 106 <i>Pseudomonas</i> spp. strains isolated from milk, whey, and spoiled dairy products. Phylogenetic analysis (based on partial <i>ileS</i> sequences) grouped most strains within the <i>P. fluorescens</i> group, clustering into the <i>P. fluorescens</i>, <i>P. gessardii</i>, <i>P. koorensis</i>, and <i>P. fragi</i> subgroups. Biofilm formation in polystyrene microplates was assessed at 6 °C and 25 °C by crystal violet staining. After 48 h, 72% and 65% of <i>Pseudomonas</i> strains formed biofilms at 6 °C and 25 °C, respectively, with higher biomass production at 6 °C. High biofilm producers included most <i>P. fluorescens</i>, <i>P. shahriarae</i>, <i>P. salmasensis</i>, <i>P. atacamensis</i>, <i>P. gessardii</i>, <i>P. koreensis,</i> and <i>P. lundensis</i> strains. The <i>adnA</i> gene, associated with biofilm formation, was detected in 60% of the biofilm producers, but was absent in <i>P. fragi</i>, <i>P. lundensis</i>, <i>P. weihenstephanensis</i>, and <i>P. putida</i>. Antibiotic susceptibility was tested using the disk diffusion method. All strains were susceptible to amikacin and tobramycin; however, 73% of the strains were resistant to aztreonam, 28% to imipenem and doripenem, 19% to ceftazidime, 13% to meropenem, and 7% to cefepime. A multiple antibiotic resistance index (MARI) > 0.2 was found in 30% of the strains, including multidrug-resistant (<i>n</i> = 15) and extensively drug-resistant (<i>n</i> = 3) strains. These findings highlight <i>Pseudomonas</i> spp. as persistent contaminants and antibiotic resistance reservoirs in dairy environments and products, posing public health risks and economic implications for the dairy industry.https://www.mdpi.com/2304-8158/14/7/1105<i>Pseudomonas</i> spp.spoilagedairy productsbiofilmantibiotic resistancephylogeny
spellingShingle Iván Briega
Sonia Garde
Carmen Sánchez
Eva Rodríguez-Mínguez
Antonia Picon
Marta Ávila
Evaluation of Biofilm Production and Antibiotic Resistance/Susceptibility Profiles of <i>Pseudomonas</i> spp. Isolated from Milk and Dairy Products
Foods
<i>Pseudomonas</i> spp.
spoilage
dairy products
biofilm
antibiotic resistance
phylogeny
title Evaluation of Biofilm Production and Antibiotic Resistance/Susceptibility Profiles of <i>Pseudomonas</i> spp. Isolated from Milk and Dairy Products
title_full Evaluation of Biofilm Production and Antibiotic Resistance/Susceptibility Profiles of <i>Pseudomonas</i> spp. Isolated from Milk and Dairy Products
title_fullStr Evaluation of Biofilm Production and Antibiotic Resistance/Susceptibility Profiles of <i>Pseudomonas</i> spp. Isolated from Milk and Dairy Products
title_full_unstemmed Evaluation of Biofilm Production and Antibiotic Resistance/Susceptibility Profiles of <i>Pseudomonas</i> spp. Isolated from Milk and Dairy Products
title_short Evaluation of Biofilm Production and Antibiotic Resistance/Susceptibility Profiles of <i>Pseudomonas</i> spp. Isolated from Milk and Dairy Products
title_sort evaluation of biofilm production and antibiotic resistance susceptibility profiles of i pseudomonas i spp isolated from milk and dairy products
topic <i>Pseudomonas</i> spp.
spoilage
dairy products
biofilm
antibiotic resistance
phylogeny
url https://www.mdpi.com/2304-8158/14/7/1105
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