Name: mrsa: host adaptation and transmission
Uploaded: 2026-03-12T13:36:05.000Z
Duration: 1 min 25 s
Channel: JoVE

La résistance aux antibiotiques est la capacité d’un microbe à résister aux effets des antibiotiques.Un agent pathogène communément connu, Staphylococcus aureus, a développé une résistance à la méthicilline, entraînant un Staphylococcus aureus résistant à la méthicilline, ou SARM (MRSA).Le MRSA provoque de graves infections cutanées et des tissus mous chez l’humain, entraînant des millions d’hospitalisations et de décès dans le monde chaque année.Les patients âgés et immunodéprimés sont les plus à risque en raison de l’utilisation prolongée et étendue d’antibiotiques à large spectre.Les stratégies pour lutter contre le MRSA incluent l’utilisation de phytochimiques, de la thérapie par phages, des nanoparticules et des probiotiques.Les phytochimiques — métabolites secondaires extraits des plantes — sont largement utilisés pour inhiber la croissance du MRSA.Les phages spécifiques au MRSA peuvent réduire les populations de MRSA en induisant la lyse cellulaire.Les nanoparticules exercent une contrainte en libérant des ions métalliques lourds dans les cellules. Elle modifie la perméabilité de la membrane et perturbe les fonctions cellulaires essentielles.Enfin, certaines souches probiotiques sécrètent des composés antimicrobiens qui inhibent la croissance du MRSA.

importance clinique de la résistance aux antibiotiques

Clinical Significance of Antibiotic Resistance

Le Staphylococcus aureus résistant à la méthicilline (MRSA) représente une menace grave pour la santé publique, découlant de sa capacité à résister aux antibiotiques β-lactamiques grâce à l’acquisition du gène mecA dans le mec du chromosome staphylococcal à cassette (SCCmec). Ce gène code pour la protéine de liaison à la pénicilline 2a (PBP2a), qui altère l’efficacité de liaison de la méthicilline et d’autres lactames β. Le MRSA a évolué en lignées clonales distinctes touchant aussi bien les humains que les animaux, renforçant son importance dans le paradigme One Health.Les souches de MRSA sont classées en associations aux soins de santé (HA-MRSA), associées à la communauté (CA-MRSA) et associées au bétail (LA-MRSA). Ces lignées présentent une variation du complexe clonal (CC) et une spécificité de l’hôte. Par exemple, le CC398 — initialement d’origine humaine — a subi une adaptation chez l’élevage, en particulier chez les porcs, entraînant sa transmission zoonotique inversée. Plusieurs CC tels que CC1, CC5, CC8 et CC97 ont été identifiés entre les espèces hôtes, impliquant un flux génétique interespèces complexe et une adaptation environnementale.La prévalence mondiale du MRSA varie considérablement. Par exemple, le CA-MRSA représente 79 % des isolats au Japon, tandis que le LA-MRSA a été détecté chez jusqu’à 38,6 % des bovins laitiers malaisiens. La colonisation LA-MRSA chez les animaux présente un risque zoonotique, en particulier pour ceux en contact étroit, comme les agriculteurs et les vétérinaires. Les rapports ont confirmé des événements de transmission entre animaux et humains, soulignant la nécessité d’une surveillance intégrée.La pathogenicité du MRSA est déterminée par un ensemble de facteurs de virulence, notamment les MSCRAMM, les entérotoxines et la leucocidine de Panton-Valentine (PVL). La formation de biofilms et les modulines solubles en phénol augmentent encore la persistance et l’évasion immunitaire. Des îlots de pathogénicité comme SaPIbov et des éléments génétiques mobiles comme SCCmec de type XI, abritant mecC , sont essentiels à l’adaptation de l’hôte. De plus, la toxine lukMF ', fortement exprimée dans les souches adaptées aux bovins, aggrave la gravité de la mammite chez les bovins laitiers.Les antibiotiques traditionnels, dont la vancomycine et la daptomycine, restent des traitements clés, bien que la résistance augmente. De nouveaux antimicrobiens tels que le tedizolid et la délafloxacine, ainsi que des approches non antibiotiques — phytochimiques, probiotiques, nanoparticules et bactériophages — montrent un potentiel prometteur. Notamment, les nanoparticules d’argent synthétisées par le vert et les souches probiotiques de Lactobacillus et Bifidobacterium ont démontré une efficacité in vitro significative contre le SARM

Importance clinique de la résistance aux antibiotiques

Methicillin-resistant Staphylococcus aureus (MRSA) presents a critical public health threat, arising from its capacity to resist &#946;-lactam antibiotics ...

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clinical-significance-of-antibiotic-resistance

Education

Enseignement

JoVE Core

Microbiology

Microbiologie

Unit

Unité

Antimicrobial Agents

Agents antimicrobiens

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

mrsa: host adaptation and transmission

MRSA, or methicillin-resistant Staphylococcus aureus, is a major public health threat. It resists beta-lactam antibiotics because it carries the mecA gene inside the staphylococcal cassette chromosome mec, or SCCmec. The mecA gene makes penicillin-binding protein 2a, which reduces how well methicillin and related beta-lactam drugs can bind.

MRSA has spread into separate clonal lineages that affect both humans and animals. These lineages fit the One Health idea, which links human, animal, and environmental health. MRSA is often grouped as healthcare-associated MRSA, community-associated MRSA, and livestock-associated MRSA. These groups also show different clonal complexes and host preferences.

One example is CC398. It began in humans, then adapted to livestock, especially pigs, and later spread back from animals to people. Other clonal complexes, including CC1, CC5, CC8, and CC97, have been found across host species. This pattern shows gene flow between species and adaptation to different environments.

MRSA prevalence also differs by region and host. Community-associated MRSA makes up 79% of isolates in Japan. Livestock-associated MRSA has been found in up to 38.6% of dairy cattle in Malaysia. Because LA-MRSA can colonize animals, it can also pose a zoonotic risk to people who work closely with them, such as farmers and veterinarians.

Transmission has also been reported between pets and humans. These findings show why integrated surveillance matters. MRSA pathogenicity is driven by virulence factors such as MSCRAMMs, enterotoxins, and Panton-Valentine leukocidin, or PVL. Biofilm formation and phenol-soluble modulins also help the bacteria persist and avoid immune attack.

Mobile genetic elements are important in host adaptation. SaPIbov and SCCmec type XI, which carries mecC, are examples. In bovine-adapted strains, the lukMF' toxin is strongly expressed and can worsen mastitis in dairy cattle. These features help explain how MRSA survives in different hosts and disease settings.

Treatment still relies on antibiotics such as vancomycin and daptomycin, but resistance is increasing. Newer drugs, including tedizolid and delafloxacin, may offer more options. Non-antibiotic strategies are also being studied, including phytochemicals, probiotics, nanoparticles, and bacteriophages. Green-synthesized silver nanoparticles and probiotic strains of Lactobacillus and Bifidobacterium have shown promising results against MRSA in laboratory studies.

MRSA: Host Adaptation and Transmission

inhibitors of gram-positive cell wall synthesis

inhibitors-of-gram-positive-cell-wall-synthesis

How Antibiotics Block Bacterial Cell Walls

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inhibitors-of-bacterial-protein-synthesis

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Interferons Block Viral Replication

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mechanism of antibiotic resistance in mrsa

mechanism-of-antibiotic-resistance-in-mrsa

How Bacteria Outsmart Antibiotics

Antibiotic resistance in bacteria happens when microbes evolve the ability to survive drugs that once killed them or slowed their growth. Genetic change and antibiotic exposure drive this process. Over time, useful treatments can stop working. Bacteria can resist antibiotics in several ways. Some make drug-inactivating enzymes, such as beta-lactamases. Others use efflux pumps to push antibiotics out of the cell. Resistance can also come from mutations that change the drug target, from lower...

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clinical significance of antibiotic resistance

MRSA, or methicillin-resistant Staphylococcus aureus, is a major public health threat. It resists beta-lactam antibiotics because it carries the mecA gene inside the staphylococcal cassette chromosome mec, or SCCmec. The mecA gene makes penicillin-binding protein 2a, which reduces how well methicillin and related beta-lactam drugs can bind. MRSA has spread into separate clonal lineages that affect both humans and animals. These lineages fit the One Health idea, which links human, animal, and...

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inhibitors-of-virion-maturation-and-assembly

HIV Protease Inhibitors and Maturation

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antiprotozoal agents

Leishmaniasis and Trypanothione Reductase

Leishmaniasis is a parasitic disease caused by several Leishmania species. It affects millions of people each year and remains a major public health problem in endemic regions. Treatment often relies on pentavalent antimonials, including meglumine antimoniate and sodium stibogluconate. The way these drugs work has not been fully clear. One important target is trypanothione reductase, or TR, an enzyme that helps keep Leishmania in redox balance. TR is not found in mammalian hosts, so it is a...

key terms and concepts

Learn how MRSA spreads between humans and animals, why it resists beta-lactam antibiotics, and what treatments and new control methods are being studied.

MRSA: Host Adaptation and Transmission | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

MRSA: Host Adaptation and Transmission

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