Estudi epidemiològic i dels patrons antimicrobians del bacteri intracel·lular facultatiu Legionella a l’ambient

El gènere Legionella va ser descobert el 1976 a arran d’un brot de pneumònia per Legionella pneumophila a Philadelphia (Estats Units) que va causar més d’una vintena de morts. Des d’aleshores, s’han publicat nombrosos estudis per conèixer més d’aquest peculiar bacteri. El gènere Legionella és un gènere present a la natura i amb un reservori principalment relacionat amb el medi aquàtic. S’estima que les seves concentracions a la natura són baixes però poden augmentar en sistemes d’aigua artificials. A l’inici de la dècada dels 1980, Rowbotham va veure que el gènere era capaç de multiplicar-se intracel·lularment a l’interior de protozous. A més, els protozous podien fer de reservori i ajudar a la disseminació de la malaltia. I així, va proposar una nova idea al camp de la microbiologia: bacteris com el gènere Legionella podien parasitar organismes unicel·lulars com les amebes i utilitzar els mateixos processos i estratègies per infectar els macròfags humans. El mecanisme de transmissió inclou la inhalació d’aerosols que continguin el bacteri i que un cop arriben als alvèols pulmonars, poden causar legionel·losi, sobretot en determinats grups de risc en la població. Amb l’era de la genòmica, aquest concepte s’ha estudiat en profunditat i s’ha vist que no només utilitzen els mateixos processos per infectar humans, sinó que manipulen les funcions de l’hoste amb proteïnes “impostores” per poder replicar-se i créixer en detriment de l’hoste. Així, utilitzen proteïnes amb motius eucariotes molt similars a les de l’hoste per dur a terme les seves funcions. Però la vida del gènere Legionella encara pot ser molt més complicada. A part de ser un bacteri intracel·lular, pot formar part de complexos biofilms o passar a un estat més resistent al qual anomenem VBNC. Així doncs, el gènere té múltiples estratègies per protegir-se i per sobreviure a la natura i, conseqüentment, es poden colonitzar els sistemes d’aigua artificials. Per evitar la disseminació i les elevades concentracions de legionel·la en aquests sistemes, s’han descrit una sèrie de mesures preventives de control d’instal·lacions i de desinfecció en continu de l’aigua. La concentració baixa d’aquests bacteris a l’aigua és la principal mesura preventiva per evitar possibles brots i disseminació de la legionel·losi. Malgrat aquestes mesures, les colonitzacions persistents en edificis d’alt risc encara són un problema de Salut Pública degut a la complexa biologia del microorganisme. L’estudi en profunditat d’aquests bacteris intracel·lulars d’aquesta tesi és clau per entendre la seva complexa ecologia i per aplicar estratègies efectives per una bona prevenció.Legionella genus was discovered after a pneumonia outbreak in Philadelphia (United States) in 1976 that caused up to twenty deaths. Since then, many research studies have been conducted to clarify different aspects of these peculiar bacteria. Legionella spp. are present naturally in different environmental ecosystems with special mention to aquatic environments. Their concentration in those habitats are estimated to be low but this may change when they are in more comfortable environmental conditions such as in man-made water systems. In the early 1980s, Rowbotham discovered that Legionella spp is capable of multiplying intracellularly inside protozoa. Moreover, they act as an environmental reservoir and can help to disseminate these bacteria. This discovery led him to a new perspective in Microbiology: Legionella genus can parasite unicellular eukaryotes like FLA and use the same processes and strategies to infect human macrophages. Aerosols containing these bacteria are responsible for the transmission of the disease and they cause LD when they arrive to the lung alveoli, especially in immunocompromised people. These concepts have been studied since then and they have been amplified using genomic techniques. Legionella spp not only they use the same processes for infecting humans but also, they can hijack important host functions and cell pathways using their “eukaryotic-like” proteins or proteins with eukaryotic domains. Those proteins mimicry the ones present in host cell pathways to manipulate host functions to the pathogen’s advantage. However, Legionella life cycle can be even more complicated. Apart from being intracellular bacteria, they can be part of complex biofilms or change into a more resistant form known as VBNC. These bacteria have several and different strategies to protect them and to survive in nature and, consequently, in colonized artificial water systems. To avoid high concentrations of Legionella in water systems and to avoid LD dissemination, many prevention strategies and disinfection methods have been described and regulated by law. Maintenance of low concentrations of Legionella in water is the key to prevent outbreaks and LD cases. Despite all these measures, there are buildings permanently colonized by Legionella spp which are still a concern for Public Health authorities. The need for studying these bacteria is what is done in this thesis and it is important to have a broader picture and to understand their complex ecology and, ultimately, to apply effective prevention strategies

Estudi epidemiològic i dels patrons antimicrobians del bacteri intracel·lular facultatiu Legionella a l’ambient

El gènere Legionella va ser descobert el 1976 a arran d’un brot de pneumònia per Legionella pneumophila a Philadelphia (Estats Units) que va causar més d’una vintena de morts. Des d’aleshores, s’han publicat nombrosos estudis per conèixer més d’aquest peculiar bacteri. El gènere Legionella és un gènere present a la natura i amb un reservori principalment relacionat amb el medi aquàtic. S’estima que les seves concentracions a la natura són baixes però poden augmentar en sistemes d’aigua artificials. A l’inici de la dècada dels 1980, Rowbotham va veure que el gènere era capaç de multiplicar-se intracel·lularment a l’interior de protozous. A més, els protozous podien fer de reservori i ajudar a la disseminació de la malaltia. I així, va proposar una nova idea al camp de la microbiologia: bacteris com el gènere Legionella podien parasitar organismes unicel·lulars com les amebes i utilitzar els mateixos processos i estratègies per infectar els macròfags humans. El mecanisme de transmissió inclou la inhalació d’aerosols que continguin el bacteri i que un cop arriben als alvèols pulmonars, poden causar legionel·losi, sobretot en determinats grups de risc en la població. Amb l’era de la genòmica, aquest concepte s’ha estudiat en profunditat i s’ha vist que no només utilitzen els mateixos processos per infectar humans, sinó que manipulen les funcions de l’hoste amb proteïnes “impostores” per poder replicar-se i créixer en detriment de l’hoste. Així, utilitzen proteïnes amb motius eucariotes molt similars a les de l’hoste per dur a terme les seves funcions. Però la vida del gènere Legionella encara pot ser molt més complicada. A part de ser un bacteri intracel·lular, pot formar part de complexos biofilms o passar a un estat més resistent al qual anomenem VBNC. Així doncs, el gènere té múltiples estratègies per protegir-se i per sobreviure a la natura i, conseqüentment, es poden colonitzar els sistemes d’aigua artificials. Per evitar la disseminació i les elevades concentracions de legionel·la en aquests sistemes, s’han descrit una sèrie de mesures preventives de control d’instal·lacions i de desinfecció en continu de l’aigua. La concentració baixa d’aquests bacteris a l’aigua és la principal mesura preventiva per evitar possibles brots i disseminació de la legionel·losi. Malgrat aquestes mesures, les colonitzacions persistents en edificis d’alt risc encara són un problema de Salut Pública degut a la complexa biologia del microorganisme. L’estudi en profunditat d’aquests bacteris intracel·lulars d’aquesta tesi és clau per entendre la seva complexa ecologia i per aplicar estratègies efectives per una bona prevenció.Legionella genus was discovered after a pneumonia outbreak in Philadelphia (United States) in 1976 that caused up to twenty deaths. Since then, many research studies have been conducted to clarify different aspects of these peculiar bacteria. Legionella spp. are present naturally in different environmental ecosystems with special mention to aquatic environments. Their concentration in those habitats are estimated to be low but this may change when they are in more comfortable environmental conditions such as in man-made water systems. In the early 1980s, Rowbotham discovered that Legionella spp is capable of multiplying intracellularly inside protozoa. Moreover, they act as an environmental reservoir and can help to disseminate these bacteria. This discovery led him to a new perspective in Microbiology: Legionella genus can parasite unicellular eukaryotes like FLA and use the same processes and strategies to infect human macrophages. Aerosols containing these bacteria are responsible for the transmission of the disease and they cause LD when they arrive to the lung alveoli, especially in immunocompromised people. These concepts have been studied since then and they have been amplified using genomic techniques. Legionella spp not only they use the same processes for infecting humans but also, they can hijack important host functions and cell pathways using their “eukaryotic-like” proteins or proteins with eukaryotic domains. Those proteins mimicry the ones present in host cell pathways to manipulate host functions to the pathogen’s advantage. However, Legionella life cycle can be even more complicated. Apart from being intracellular bacteria, they can be part of complex biofilms or change into a more resistant form known as VBNC. These bacteria have several and different strategies to protect them and to survive in nature and, consequently, in colonized artificial water systems. To avoid high concentrations of Legionella in water systems and to avoid LD dissemination, many prevention strategies and disinfection methods have been described and regulated by law. Maintenance of low concentrations of Legionella in water is the key to prevent outbreaks and LD cases. Despite all these measures, there are buildings permanently colonized by Legionella spp which are still a concern for Public Health authorities. The need for studying these bacteria is what is done in this thesis and it is important to have a broader picture and to understand their complex ecology and, ultimately, to apply effective prevention strategies

Estudi epidemiològic i dels patrons antimicrobians del bacteri intracel·lular facultatiu Legionella a l'ambient /

El gènere Legionella va ser descobert el 1976 a arran d'un brot de pneumònia per Legionella pneumophila a Philadelphia (Estats Units) que va causar més d'una vintena de morts. Des d'aleshores, s'han publicat nombrosos estudis per conèixer més d'aquest peculiar bacteri. El gènere Legionella és un gènere present a la natura i amb un reservori principalment relacionat amb el medi aquàtic. S'estima que les seves concentracions a la natura són baixes però poden augmentar en sistemes d'aigua artificials. A l'inici de la dècada dels 1980, Rowbotham va veure que el gènere era capaç de multiplicar-se intracel·lularment a l'interior de protozous. A més, els protozous podien fer de reservori i ajudar a la disseminació de la malaltia. I així, va proposar una nova idea al camp de la microbiologia: bacteris com el gènere Legionella podien parasitar organismes unicel·lulars com les amebes i utilitzar els mateixos processos i estratègies per infectar els macròfags humans. El mecanisme de transmissió inclou la inhalació d'aerosols que continguin el bacteri i que un cop arriben als alvèols pulmonars, poden causar legionel·losi, sobretot en determinats grups de risc en la població. Amb l'era de la genòmica, aquest concepte s'ha estudiat en profunditat i s'ha vist que no només utilitzen els mateixos processos per infectar humans, sinó que manipulen les funcions de l'hoste amb proteïnes "impostores" per poder replicar-se i créixer en detriment de l'hoste. Així, utilitzen proteïnes amb motius eucariotes molt similars a les de l'hoste per dur a terme les seves funcions. Però la vida del gènere Legionella encara pot ser molt més complicada. A part de ser un bacteri intracel·lular, pot formar part de complexos biofilms o passar a un estat més resistent al qual anomenem VBNC. Així doncs, el gènere té múltiples estratègies per protegir-se i per sobreviure a la natura i, conseqüentment, es poden colonitzar els sistemes d'aigua artificials. Per evitar la disseminació i les elevades concentracions de legionel·la en aquests sistemes, s'han descrit una sèrie de mesures preventives de control d'instal·lacions i de desinfecció en continu de l'aigua. La concentració baixa d'aquests bacteris a l'aigua és la principal mesura preventiva per evitar possibles brots i disseminació de la legionel·losi. Malgrat aquestes mesures, les colonitzacions persistents en edificis d'alt risc encara són un problema de Salut Pública degut a la complexa biologia del microorganisme. L'estudi en profunditat d'aquests bacteris intracel·lulars d'aquesta tesi és clau per entendre la seva complexa ecologia i per aplicar estratègies efectives per una bona prevenció.Legionella genus was discovered after a pneumonia outbreak in Philadelphia (United States) in 1976 that caused up to twenty deaths. Since then, many research studies have been conducted to clarify different aspects of these peculiar bacteria. Legionella spp. are present naturally in different environmental ecosystems with special mention to aquatic environments. Their concentration in those habitats are estimated to be low but this may change when they are in more comfortable environmental conditions such as in man-made water systems. In the early 1980s, Rowbotham discovered that Legionella spp is capable of multiplying intracellularly inside protozoa. Moreover, they act as an environmental reservoir and can help to disseminate these bacteria. This discovery led him to a new perspective in Microbiology: Legionella genus can parasite unicellular eukaryotes like FLA and use the same processes and strategies to infect human macrophages. Aerosols containing these bacteria are responsible for the transmission of the disease and they cause LD when they arrive to the lung alveoli, especially in immunocompromised people. These concepts have been studied since then and they have been amplified using genomic techniques. Legionella spp not only they use the same processes for infecting humans but also, they can hijack important host functions and cell pathways using their "eukaryotic-like" proteins or proteins with eukaryotic domains. Those proteins mimicry the ones present in host cell pathways to manipulate host functions to the pathogen's advantage. However, Legionella life cycle can be even more complicated. Apart from being intracellular bacteria, they can be part of complex biofilms or change into a more resistant form known as VBNC. These bacteria have several and different strategies to protect them and to survive in nature and, consequently, in colonized artificial water systems. To avoid high concentrations of Legionella in water systems and to avoid LD dissemination, many prevention strategies and disinfection methods have been described and regulated by law. Maintenance of low concentrations of Legionella in water is the key to prevent outbreaks and LD cases. Despite all these measures, there are buildings permanently colonized by Legionella spp which are still a concern for Public Health authorities. The need for studying these bacteria is what is done in this thesis and it is important to have a broader picture and to understand their complex ecology and, ultimately, to apply effective prevention strategies

Pseudomonas aeruginosaPseudomonas\ aeruginosa antimicrobial susceptibility profiles, resistance mechanisms and international clonal lineages: update from ESGARS-ESCMID/ISARPAE Group

International audienceScopePseudomonas aeruginosa, a ubiquitous opportunistic pathogen considered one of the paradigms of antimicrobial resistance, is among the main causes of hospital-acquired and chronic infections associated with significant morbidity and mortality. This growing threat results from the extraordinary capacity of P. aeruginosa to develop antimicrobial resistance through chromosomal mutations, the increasing prevalence of transferable resistance determinants (such as the carbapenemases and the extended spectrum β-lactamases), and the global expansion of epidemic lineages. The general objective of this initiative is to provide a comprehensive update of P. aeruginosa resistance mechanisms, especially for the extensively drug-resistant (XDR)/difficult to treat resistance (DTR) international high-risk epidemic lineages, and how the recently approved β-lactams and β-lactam/β-lactamase inhibitor combinations may affect resistance mechanisms and the definition of susceptibility profiles.MethodsTo address this challenge, the European Study Group for Antimicrobial Resistance Surveillance (ESGARS) from the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) launched the “Improving Surveillance of Antibiotic-Resistant Pseudomonas aeruginosa in Europe” (ISARPAE) initiative in 2022, supported by the Joint programming initiative on antimicrobial resistance (JPIAMR) network call and included a panel of over 40 researchers from 18 European Countries. Thus, an ESGARS-ISARPAE position paper was designed and the final version agreed after four rounds of revision and discussion by all panel members.Questions addressed in the position paperTo provide an update on (i) the emerging resistance mechanisms to classical and novel antipseudomonal agents, with a particular focus on β-lactams, (ii) the susceptibility profiles associated with the most relevant β-lactam resistance mechanisms, (iii) the impact of the novel agents and resistance mechanisms on the definitions of resistance profiles and (iv) the globally expanding XDR/DTR high-risk lineages and their association with transferable resistance mechanisms.ImplicationThe evidence presented herein can be used for coordinated epidemiological surveillance and decision-making at the European and global level

Pseudomonas aeruginosa antimicrobial susceptibility profiles, resistance mechanisms and international clonal lineages: update from ESGARS-ESCMID/ISARPAE Group

Scope: Pseudomonas aeruginosa, a ubiquitous opportunistic pathogen considered one of the paradigms of antimicrobial resistance, is among the main causes of hospital-acquired and chronic infections associated with significant morbidity and mortality. This growing threat results from the extraordinary capacity of P. aeruginosa to develop antimicrobial resistance through chromosomal mutations, the increasing prevalence of transferable resistance determinants (such as the carbapenemases and the extended spectrum β-lactamases), and the global expansion of epidemic lineages. The general objective of this initiative is to provide a comprehensive update of P. aeruginosa resistance mechanisms, especially for the extensively drug-resistant (XDR)/difficult to treat resistance (DTR) international high-risk epidemic lineages, and how the recently approved β-lactams and β-lactam/β-lactamase inhibitor combinations may affect resistance mechanisms and the definition of susceptibility profiles. Methods: To address this challenge, the European Study Group for Antimicrobial Resistance Surveillance (ESGARS) from the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) launched the "Improving Surveillance of Antibiotic-Resistant Pseudomonas aeruginosa in Europe" (ISARPAE) initiative in 2022, supported by the Joint programming initiative on antimicrobial resistance (JPIAMR) network call and included a panel of over 40 researchers from 18 European Countries. Thus, an ESGARS-ISARPAE position paper was designed and the final version agreed after four rounds of revision and discussion by all panel members. Questions addressed in the position paper: To provide an update on (i) the emerging resistance mechanisms to classical and novel antipseudomonal agents, with a particular focus on β-lactams, (ii) the susceptibility profiles associated with the most relevant β-lactam resistance mechanisms, (iii) the impact of the novel agents and resistance mechanisms on the definitions of resistance profiles and (iv) the globally expanding XDR/DTR high-risk lineages and their association with transferable resistance mechanisms. Implication: The evidence presented herein can be used for coordinated epidemiological surveillance and decision-making at the European and global level