Mondialisation de la résistance bactérienne aux antibiotiques

Global dissemination of bacterial resistance to antimicrobials

Service de Microbiologie, CHU de Caen, Avenue de la Côte de Nacre, 14033, Caen Cedex, France.

^* leclercq-r@chu-caen.fr

Résumé

La dissémination mondiale de la résistance bactérienne aux antibiotiques n'est pas u n fait nouveau. Cependant, elle atteint maintenant plusieurs bactéries responsables d'infections communautaires et des antibiotiques importants pour le traitement de ces infections. L'émergence récente de la résistance à la méticilline chez les souches communautaires de Staphylococcus aureus est couplée à une plus grande virulence des souches qui produisent une toxine associée aux infections cutanées et à des pneumonies. Un autre exemple récent est la brutale émergence des Escherichia coli communautaires résistants aux céphalosporines de troisième génération par production de β-lactamase CTX-M et qui peuvent atteindre des sujets sans facteur de risque particulier. Les échanges internationaux et les circulations de population expliquent, mais seulement en partie, la dissémination à grande échelle de ces résistances. Le contrôle d e la dissémination des souches résistantes en communauté est un défi qu'il importe de relever sous peine de perdre le bénéfice de nos antibiotiques les plus actifs.

Abstract

Spread of bacterial resistance to antimicrobials is related to the transmissibility of resistant bacteria, but also to the spread of plasmids from bacteria to bacteria and of transposons from DNA to DNA. Global spread of antimicrobial resistance is not new. It has first been observed in the 1940s with the resistance of Staphylococus aureus to penicillins by production of penicillinase due to plasmids that disseminated in strains from ail continents. Resistance to ampicillin in E. coli and more recently to penicillins in pneumococci are additional examples. Success of résistant clones depends on several factors, including fitness of the bacterial clone and antibiotic sélective pressure. Recently, community acquired methicillin-resistant S. aureus have emerged worldwide. The isolates combine antibiotic resistance and increased virulence due to the secretion of a Panton-Valentine toxin. They are highly prevalent in certain countries such as the USA and are a major cause of cutaneous infections in children. Although, initially, each continent had a specifie staphylococcal clone, a greater diversity of clonal types has recently been shown within each continent, related in part to exchange of isolates via international travels. The emergence in the community of E. coli producing CTX-M type extended spectrum beta-lactamase is another cause of concern. Patients without any risk factors may present urinary infections due to this type of microorganism, Again, various types of CTX-Menzymes are described that are more or less predominant according to the country. International exchanges may also, in part, explain the global spread of resistant isolates, although other non identified factors seem to be involved. Control of the spread of antibiotic-resistant microorganisms is an important challenge and is required to preserve our armentarium of antibiotics.