Antimicrobial Resistance Profile and Biofilm Formation of <i>Listeria monocytogenes</i> Isolated from Meat
Introduction: <i>Listeria monocytogenes</i> is the causative agent of listeriosis, a serious infectious disease with one of the highest case fatality rates among foodborne diseases affecting humans. Objectives: This study investigated the prevalence, antimicrobial resistance pattern and...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-04-01
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| Series: | Antibiotics |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2079-6382/14/5/454 |
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| Summary: | Introduction: <i>Listeria monocytogenes</i> is the causative agent of listeriosis, a serious infectious disease with one of the highest case fatality rates among foodborne diseases affecting humans. Objectives: This study investigated the prevalence, antimicrobial resistance pattern and biofilm production capacity of <i>L. monocytogenes</i> isolated in meats. Materials: A total of 75 samples were analyzed, including fresh meats and meat preparations, in Northern Portugal. Methods: The strains were identified using morphological and molecular methods. Antimicrobial resistance was determined using the Kirby–Bauer disk diffusion method, against a panel of 12 antibiotics and the presence of the respective antimicrobial resistance genes was investigated by polymerase chain reaction (PCR). The ability to form biofilms was evaluated by the microtiter biofilm assay. Results: The overall prevalence of <i>L. monocytogenes</i> among screened samples was 17.33%. The isolates were resistant to trimethoprim-sulfamethoxazole (85.71%), ciprofloxacin (38.10%), meropenem (33.33%), tetracycline and erythromycin (28.57%), rifampicin (23.81%), and kanamycin (14.29%). Six isolates (28.57%) exhibited a multidrug-resistance profile. All strains showed positive result for the virulence gene specific to listeriolysin O (<i>hly</i>A). In the genotypic resistance analysis of the strains, the genes identified were <i>tet</i>K (23.81%), <i>aad</i>A, <i>tet</i>L, <i>bla</i><sub>OXA-48</sub> (14.29%), <i>erm</i>C, and <i>msr(A/B)</i> (4.76%). All isolates had the ability to form biofilms, with no significant differences in biofilm biomass production at 24 h and 48 h. Some of these strains showed a high capacity for biofilm production. Conclusions: These findings raise public health concerns due to resistance to first-line antibiotics and the biofilm-forming capacity of these isolates, which pose risks to the food industry. Enhanced monitoring and surveillance are essential to guide public health strategies in order to mitigate the threat posed by <i>L. monocytogenes</i> in food. |
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| ISSN: | 2079-6382 |