Impacto de la multirresistencia en la patogenicidad de Pseudomonas aeruginosa: perspectiva epidemiológica-clinica y experimental

[spa] P. aeruginosa es uno de los principales patógenos nosocomiales y posee una gran capacidad de desarrollar resistencias a los antimicrobianos con la emergencia de cepas multirresistentes (MDR) y extremadamente resistentes (XDR). En las últimas décadas se ha producido un incremento de las infecciones por cepas multirresistentes que plantea la necesidad de desarrollar estrategias de control de infección y un uso prudente de los antimicrobianos. En este contexto se desarrolla la presente tesis doctoral en la que se incluyen ocho trabajos publicados en revistas científicas, que están encaminados tanto a mejorar el conocimiento epidemiológico de P. aeruginosa como a evaluar el impacto de la multirresistencia en la patogenicidad y virulencia de P. aeruginosa desde una perspectiva clínica, epidemiológica y experimental. La posible existencia de un coste biológico asociado a la multirresistencia supondría una menor virulencia de las cepas multirresistentes y podría justificar un uso más selectivo de las antibioticoterapias empíricas. Este proyecto doctoral incluye un estudio retrospectivo de neumonías asociada a ventilación mecánica por P. aeruginosa en el que se demostró que la mortalidad precoz era superior en las causadas por cepas no multirresistentes que en aquellas causadas por cepas multirresistentes. En un segundo estudio retropectivo, se identificó el consumo de fluoroquinolonas como principal factor de riesgo para el desarrollo de bacteriemia por P. aeruginosa XDR. Esta tesis incluye un estudio observacional prospectivo en el que se realizó vigilancia activa de colonización intestinal y de infección por P. aeruginosa. Gracias a este estudio se demostró que: 1) la colonización intestinal por cepas de P. aeruginosa MDR es más tardía que la colonización por cepas sensibles; 2) el consumo previo de fluoroquinolonas y carbapenémicos son los principales factores de riesgo para la colonización por P. aeruginosa multirresistente; 3) la colonización intestinal es un requerimiento clave para el desarrollo posterior de infección por P. aeruginosa; 4) la invasividad clínica fue mayor en las cepas no multirresistentes que en las multirresistentes, desarrollando los pacientes colonizados por cepas de P. aeruginosa no multirresistente con más frecuencia y precocidad infección que aquellos colonizados por cepas multirresistentes policlonales; 5) la intensidad de la respuesta inflamatoria se asoció con la severidad de la infección por P. aeruginosa, especialmente en infecciones bacteriémicas y 6) la respuesta inflamatoria fue superior en las infecciones por P. aeruginosa XDR en las que había un mayor porcentaje de infecciones bacteriémicas. En esta tesis también se incluye un estudio multicéntrico de pacientes con bacteriemia por P. aeruginosa se investigaron los genotipos del sistema de secreción tipo III y su relación con el pronóstico de los pacientes; demostrándose que el genotipo exoU+ es uno de los principales determinantes de virulencia de P. aeruginosa y se asocia a una mayor mortalidad precoz. Este genotipo fue más frecuente en los fenotipos no multirresistentes que en los multirresistentes. Finalmente, mediante un modelo experimental in vitro e in vivo se evaluó el impacto de la multirresistencia en la patogenicidad y virulencia de P. aeruginosa. En el modelo de peritonitis-sepsis murino se observó que las cepas multirresistentes presentaron menor capacidad de producir infección localizada y diseminada, menor capacidad de producir respuesta inflamatoria y menor mortalidad que las cepas sensibles. En conjunto, nuestros resultados sugieren que las cepas de Pseudomonas aeruginosa multirresistente producen una colonización más tardía y sufren un coste biológico, manifestado con una menor tasa de crecimiento in vitro, una menor invasividad clínica, una menor capacidad de producir respuesta inflamatoria y una menor mortalidad atribuible de las cepas multirresistentes. Esto permite considerar un mayor margen en el abordaje empírico de estas situaciones clínicas y una utilización más ajustada de la antibioterapia.[eng] Pseudomonas aeruginosa is one of the most common nosocomial pathogens worldwide, and continuously evolving resistance to multiple antimicrobial agents has become a significant health problem. However, the biological implications of antibiotic resistance on the pathogenicity and virulence of P. aeruginosa are not clearly established. It is believed that acquisition of resistance mechanisms may have a negative impact on bacterial fitness (a fitness cost), resulting in impaired bacterial physiology and, in turn, a loss of virulence. Improve knowledge about the possible biological cost associated with resistance may help to implement infection control strategies as well as improve antibiotic prescription. In this context, this doctoral thesis evaluates the impact of multidrug resistance on the pathogenicity of P. aeruginosa through epidemiological, clinical and experimental studies. Using clinical and epidemiological data, we investigated if there were differences in the outcome, in the ability to develop colonization and infection between multidrug resistant (MDR) and non-MDR P. aeruginosa strains. In a retrospective study we observed that early mortality was higher in ventilator-associated pneumonia caused by non-MDR P. aeruginosa than those caused by MDR strains. In a prospective study we demonstrated that intestinal colonization occurred more prematurely for non-MDR P. than for MDR isolates. The ability to produce infection (clinical invasiveness) was also higher in patient colonized by non-MDR isolates than those colonized by MDR strains. Furthermore, using in vitro and in vivo models we demonstrated that MDR profiles were associated with a reduction in virulence of P. aeruginosa. In vitro growth rate was shorter in non-MDR than in MDR isolates. In a mice peritonitis/sepsis model we observed that non-MDR P. aeruginosa isolates had a greater ability to produce infection, to elicit inflammatory response and to cause mortality than MDR strains. Overall, our data suggest that multidrug resistance is associated with a biological cost in P. aeruginosa

Impact of generic entry on hospital antimicrobial use: a retrospective quasi-experimental interrupted time series analysis

Background: the impact of antimicrobials generic entry (GE) is controversial. Their introduction could provide an economic benefit yet may also increase their consumption, leadingto a higher risk of resistance. Our aim was to analyze the impact of GE on trends of antimicrobialconsumption in an acute-care hospital. Methods: a retrospective quasi-experimental interrupted timeseries analysis was conducted at a 400-bed tertiary hospital in Barcelona, Spain. All antimicrobials forsystemic use for which a generic product entered the hospital from January 2000 to December 2019 were included. Antimicrobial consumption was expressed as DDD/100 bed days. Results: after GE, the consumption of cefotaxime (0.09,p< 0.001), meropenem (0.54,p< 0.001), and piperacillin-tazobactam (0.13,p< 0.001) increased, whereas the use of clindamycin (−0.03,p< 0.001) anditraconazole (−0.02,p= 0.01) was reduced. An alarming rise in cefepime (0.004), daptomycin (1.02),and cloxacillin (0.05) prescriptions was observed, despite not achieving statistical significance. Onthe contrary, the use of amoxicillin (−0.07), ampicillin (−0.02), cefixime (−0.06), fluconazole (−0.13),imipenem-cilastatin (−0.50) and levofloxacin (−0.35) decreased. These effects were noticed beyondthe first year post GE. Conclusions: GE led to an increase in the consumption of broad-spectrummolecules. The potential economic benefit of generic antibiotics could be diluted by an increase inresistance. Antimicrobial stewardship should continue to monitor these molecules despite GE

Streptococcus suis infection and malignancy in man, Spain

Streptococcus suis is an emerging zoonotic agent. Human infection is associated with occupational exposure to swine. Affected persons are usually, but not always, healthy (1,2). Immunosuppressive conditions can predispose persons to S. suis infection, and cancer has classically been associated as a risk factor for S. suis infection (1,2). Nevertheless, the actual number of reported cases is low (27). We describe a severe case of S. suis infection in a man who had not been exposed to swine but for whom disseminated cancer was diagnosed 5 months after the infection

Acute inflammatory response of patients with Pseudomonas aeruginosa infections: a prospective study

The severity of Pseudomonas aeruginosa (PA) infection may be determined by the interaction with the host immune system. We designed a prospective study to assess the relationship between the inflammatory response and the clinical presentation and outcome of PA infection. We also investigated whether there are differences in the inflammatory response depending on the resistance profile of PA. Interleukin-6 (IL-6), IL-10, procalcitonin (PCT), and C-reactive protein (CRP) were measured. Sixty-nine infection episodes were recorded; 40 caused by non-multidrug-resistant (non-MDR) strains [29 (73%) respiratory; 8 (20%) bacteremia], 12 by MDR non-extensively drug-resistant (MDR-non-XDR) [9 (75%) respiratory; 3 (25%) bacteremia], and 17 by XDR strains [9 (53%) respiratory; 7 (41%) bacteremia]. All inflammatory parameters were significantly higher in patients who developed acute organ dysfunction and bacteremia. PCT levels were higher in patients with early mortality [p = 0.050]. Inflammatory biomarkers were higher in patients with XDR than in those with non-MDR PA [IL-6 430 (67-951) vs. 77 (34-216), p = 0.02; IL-10 3.3 (1.5-16.3) vs. 1.3 (0-3.9), p = 0.02; and PCT 1.1 (0.6-5.2) vs. 0.3 (0.1-1.0), p = 0.008]. The intensity of inflammatory response was associated with the severity of PA infection, particularly if bacteremia occurred. Only PCT was documented useful to predict the outcome. XDR infections presented a higher inflammatory response; related in part to the larger number of bloodstream infections in this group

The balance between antibiotic resistance and fitness/virulence in Pseudomonas aeruginosa: an update on basic knowledge and fundamental research

The interplay between antibiotic resistance and bacterial fitness/virulence has attracted the interest of researchers for decades because of its therapeutic implications, since it is classically assumed that resistance usually entails certain biological costs. Reviews on this topic revise the published data from a general point of view, including studies based on clinical strains or in vitro-evolved mutants in which the resistance phenotype is seen as a final outcome, i.e., a combination of mechanisms. However, a review analyzing the resistance/fitness balance from the basic research perspective, compiling studies in which the different resistance pathways and respective biological costs are individually approached, was missing. Here we cover this gap, specifically focusing on Pseudomonas aeruginosa, a pathogen that stands out because of its extraordinary capacity for resistance development and for which a considerable number of recent and particular data on the interplay with fitness/virulence have been released. The revised information, split into horizontally-acquired vs. mutation-driven resistance, suggests a great complexity and even controversy in the resistance-fitness/virulence balance in the acute infection context, with results ranging from high costs linked to certain pathways to others that are seemingly cost-free or even cases of resistance mechanisms contributing to increased pathogenic capacities. The elusive mechanistic basis for some enigmatic data, knowledge gaps, and possibilities for therapeutic exploitation are discussed. The information gathered suggests that resistance-fitness/virulence interplay may be a source of potential antipseudomonal targets and thus, this review poses the elementary first step for the future development of these strategies harnessing certain resistance-associated biological burdens

Evolution of Antimicrobial Consumption During the First Wave of COVID-19 Pandemic

Background: The first wave of COVID-19 pandemic may have significantly impacted antimicrobial consumption in hospitals. The objective of this study was to assess the evolution of antimicrobial consumption during this period. Methods : A retrospective quasi-experimental before-after study was conducted in a Spanish tertiary care hospital. The study compared two periods: pre-pandemic, from January 2018 to February 2020, and during the COVID-19 pandemic from March to June 2020. Antimicrobial consumption was analyzed monthly as defined daily doses (DDD)/100 bed-days and overall hospital and ICU consumption were evaluated. Results: An increase in the hospital consumption was noticed. Although only ceftaroline achieved statistical significance (p = 0.014), a rise was observed in most of the studied antimicrobials. A clear temporal pattern was detected. While an increase in ceftriaxone and azithromycin was observed during March, an increment in the consumption of daptomycin, carbapenems, linezolid, ceftaroline, novel cephalosporin/β-lactamase inhibitors or triazoles during April-May was noticed. In the ICU, these findings were more evident, namely ceftriaxone (p = 0.029), carbapenems (p = 0.002), daptomycin (p = 0.002), azithromycin (p = 0.030), and linezolid (p = 0.011) but followed a similar temporal pattern. Conclusion : An increase in the antimicrobial consumption during the first wave of COVID-19 pandemic was noticed, especially in the ICU. Availability of updated protocols and antimicrobial stewardship programs are essential to optimize these outcomes

Arabidopsis SWC4 Binds DNA and Recruits the SWR1 Complex to Modulate Histone H2A.Z Deposition at Key Regulatory Genes

Deposition of the H2A.Z histone variant by the SWR1 complex (SWR1-C) in regulatory regions of specific loci modulates transcription. Characterization of mutations in Arabidopsis thaliana homologs of yeast SWR1-C has revealed a role for H2A.Z exchange in a variety of developmental processes. Nevertheless, the exact composition of plant SWR1-C and how it is recruited to target genes remains to be established. Here we show that SWC4, the Arabidopsis homolog of yeast SANT domain protein Swc4/Eaf2, is a DNA-binding protein that interacts with SWR1-C subunits. We demonstrate that the swc4-1 knockout mutant is embryo-lethal, while SWC4 RNAi knockdown lines display pleiotropic phenotypic alterations in vegetative and reproductive traits, including acceleration of flowering time, indicating that SWC4 controls post-embryonic processes. Transcriptomic analyses and genome-wide profiling of H2A.Z indicate that SWC4 represses transcription of a number of genes, including the floral integrator FT and key transcription factors, mainly by modulating H2A.Z deposition. Interestingly, SWC4 silencing does not affect H2A.Z deposition at the FLC locus nor expression of this gene, a master regulator of flowering previously shown to be controlled by SWR1-C. Importantly, we find that SWC4 recognizes specific AT-rich DNA elements in the chromatin regions of target genes and that SWC4 silencing impairs SWR1-C binding at FT. Collectively, our data suggest that SWC4 regulates plant growth and development by aiding SWR1-C recruitment and modulating H2A.Z deposition.This work was supported by grants BIO2010-15589, BIO2013-43098-R, and BIO2016-77559-R to J.A.J. and M.P., and grant RYC-2013-14689 to P.C. from the Spanish Ministerio de Economia y Competitividad (MINECO/FEDER, EU), and Marie Curie FP7-PEOPLE-2011-IEF grant 298790 to P.C. and J.A.J. from the European Commission. The CBGP is a Severo Ochoa Center of Excellence (SEV-2016-0672). The CNIC is supported by the Spanish Ministerio de Economia, Industria y Competitividad and the Pro CNIC Foundation, and is also a Severo Ochoa Center of Excellence (SEV-2015-0505).S

Risk Factors for Amoxicillin-Clavulanate Resistance in Community-Onset Urinary Tract Infections Caused by Escherichia coli or Klebsiella pneumoniae : The Role of Prior Exposure to Fluoroquinolones

Background: High rates of amoxicillin-clavulanate (AMC) resistance among Enterobacterales isolated from urinary tract infections (UTIs) were observed in our area. The aim of this study was to identify risk factors associated with AMC resistance in patients with community-onset UTI in emergency departments (EDs). Methods: A retrospective study was performed of all ED patients with positive urine cultures for Escherichia coli or Klebsiella pneumoniae in a Spanish tertiary-care hospital. Results: 330 urine cultures in all were included: 261 (79.1%) for E. coli and 69 (20.90%) for K. pneumonia. Rates of AMC resistance were 14.94% and 34.78%, respectively. UTI was clinically confirmed in 212 (64.24%) cases. Previous antimicrobial exposure was independently associated with AMC resistance development in E. coli and K. pneumoniae urinary isolates (OR = 2.94, 95% CI = 1.55-5.58). Analyses of infected patients revealed that previous exposure to fluoroquinolones (OR = 3.33, 95% CI = 1.10-10.12, p = 0.034) and to AMC (OR = 5.68, 95% CI = 1.97-16.44, p = 0.001) was significantly associated with isolation of AMC-resistant strains. Conclusions: Prior antibiotic exposure, particularly to AMC or fluoroquinolones, was the only independent risk factor associated with development of AMC resistance in E. coli and K. pneumoniae urinary isolates from patients attending the ED

Genomic value of isocitrate-dehydrogenase (IDH1/2) in glioma origin and progression (ONCOLGroup)

Las mutaciones heterocigotas del gen que codifica la isocitrato deshidrogenasa (IDH) ocurren con relativa frecuencia en los gliomas; sin embargo, su relevancia durante el desarrollo tumoral es desconocida. Estas alteraciones provocan una pérdida en la afinidad de la enzima por el sustrato, inhibiendo la actividad de la isoforma silvestre de la IDH1 a través de la formación de heterodímeros inactivos. La expresión forzada de la mutación IDH1/2 en cultivos celulares reduce la formación del producto de la enzima, el α-ketoglutarato (α-KG), e incrementa los niveles del factor inducido por la hipoxia tipo 1 (HIF-1α, un elemento de transcripción que facilita el crecimiento tumoral en presencia de bajas concentraciones de oxígeno, hallazgo regulado en parte por el α-KG. La expresión del HIF-1α suele ser mayor entre los gliomas portadores de la mutación IDH, en los que la vía de señalización del HIF está implicada en su progresión. Varios grupos independientes han demostrado el papel que tienen las mutaciones del gen IDH1/2 como marcador pronóstico, especialmente para los pacientes con gliomas de bajo grado y con glioblastomas secundarios que presentan un patrón oligodendroglial. Este conocimiento proporciona una clara oportunidad para mejorar las estrategias diagnósticas y terapéuticas para los pacientes con gliomas, que en la actualidad no se encuentran dirigidas contra alteraciones moleculares específicas. Este artículo presenta una revisión detallada del papel de las mutaciones del gen IDH en la progresión y el mantenimiento de los gliomas, y explora algunas opciones terapéuticas dirigidas contra este entorno.Revisión de tema22-33Heterozygous mutations in the gene encoding isocitrate dehydrogenase (IDH) occur in gliomas, but their mechanistic role in tumor development is unknown. Tumor-derived IDH mutations impair the enzyme affinity for its substrate and dominantly inhibit wild-type IDH1 activity through the formation of catalytically inactive heterodimers. Forced expression of mutant IDH1 in cultured cells reduces formation of the enzyme product, α-ketoglutarate (α-KG), and increases the levels of hypoxia-inducible factor subunit 1 (HIF-1α, a transcription factor that facilitates tumor growth when oxygen is low and whose stability is regulated by α-KG. HIF-1α levels were higher in human gliomas harboring an IDH1 mutation than in tumors without a mutation, thus, IDH1/2 contributes to tumor progression in part through induction of the HIF-1 pathway. Numerous independent research groups had demonstrated the role of IDH mutations as a prognostic marker, especially for those patients with low grade gliomas and secondary glioblastomas with oligodendroglial pattern. This knowledge indicates great opportunities to improve diagnostic and therapeutic strategies for gliomas, which are not currently targeted at the specific molecular alterations. This paper presents a detailed review of the role of the IDH gene mutations in progression and manteinance of gliomas, and explores some therapeutic options directed against this environment

Randomized Clinical Trial of the Need for Antibiotic Treatment for Low-Risk Catheter-Related Bloodstream Infection Caused by Coagulase-Negative Staphylococci

According to clinical guidelines, the management of catheter-related bloodstream infections (CRBSI) due to coagulase-negative staphylococci (CoNS) includes catheter removal and antibiotic treatment for 5 to 7 days. However, in low-risk episodes, it remains uncertain whether antibiotic therapy is necessary. This randomized clinical trial aims to determine whether the non-administration of antibiotic therapy is as safe and effective as the recommended strategy in low-risk episodes of CRBSI caused by CoNS. With this purpose, a randomized, open-label, multicenter, non-inferiority clinical trial was conducted in 14 Spanish hospitals from 1 July 2019 to 31 January 2022. Patients with low-risk CRBSI caused by CoNS were randomized 1:1 after catheter withdrawal to receive/not receive parenteral antibiotics with activity against the isolated strain. The primary endpoint was the presence of any complication related to bacteremia or to antibiotic therapy within 90 days of follow-up. The secondary endpoints were persistent bacteremia, septic embolism, time until microbiological cure, and time until the disappearance of a fever. EudraCT: 2017-003612-39 INF-BACT-2017. A total of 741 patients were assessed for eligibility. Of these, 27 were included in the study; 15 (55.6%) were randomized to the intervention arm (non-antibiotic administration) and 12 (44.4%) to the control arm (antibiotic therapy as per standard practice). The primary endpoint occurred in one of the 15 patients in the intervention group (septic thrombophlebitis) and in no patients in the control group. The median time until microbiological cure was 3 days (IQR 1-3) in the intervention arm and 1.25 days (IQR 0.5-2.62) in the control arm, while the median time until fever resolution was zero days in both arms. The study was stopped due to the insufficient number of recruited patients. These results seem to indicate that low-risk CRBSI caused by CoNS can be managed without antibiotic therapy after catheter removal; efficacy and safety are not affected