Dependencia a colistina debida a la pérdida de lipolisacáridos en Acinetobacter baumannii

Motivación: Determinar la causa genotípica de la dependencia a colistina (1) en Acinetobacter baumannii de estirpes seleccionadas resistentes a colistina, el cual es un antibiótico muy utilizado en clínica para combatir cepas múltirresistentes. Estos mutantes presentan una mutación de pérdida de función en genes esenciales para la biosíntesis del lípido A, que forma parte del lipopolisacáridos (LPS). Henry et al. demostraron que estas estirpes sin LPS tienen alterados los niveles de expresión de otros genes que dan lugar, entre otras cosas, al incremento de sistemas de transporte de lipoproteínas, fosfolípidos y exopolisacáridos para compensar la pérdida del LPS en la membrana externa (2). Por tanto, este fenómeno produce la modificación de la membrana con la consecuente resistencia a colistina y un aumento de permeabilidad.Métodos: Se utilizaron cinco cepas clínicas multirresistentes aisladas de pacientes infectados en las UCIs del hospital Virgen del Rocío, una estirpe tipo sensible. Además, se incluyó una estirpe resistente a colistina con una modificación en el LPS en lugar de ausencia del mismo. Para visualizar la dependencia a colistina, en primer lugar se realizaron ensayos E-test en placas de medio rico con Mueller Hinton Broth (MBHII), usando tiras de colistina. El efecto de dependencia a colistina se estudió en curvas de crecimiento en medio líquido MHBII en agitación a 37ºC en placas multipocillos, comparando el número de ufc/ml de la misma estirpe en ausencia o presencia de colistina a 5 μg/ml.Resultados: Todas las estipes clínicas presentaron una concentración mínima inhibitoria a colistina >256 μg/ml, mientras que la de la estirpe tipo resistente a colistina fue de 48 μg/ml y la cepa con LPS modificado fue 32 μg/ml. Sólo en las cepas sin LPS se observó un halo de mayor crecimiento alrededor de la tira en comparación a la zona alejada de la misma, lo que indica la dependencia a este antibiótico.Respecto a la curva de crecimiento, la presencia de colistina aceleró la entrada en fase exponencial en todas las estirpes en comparación al medio rico sin colistina, alcanzando 1,71 veces más crecimiento en colistina a las 24 horas.Conclusiones: Nuestros resultados muestran que la pérdida de LPS no sólo confiere resistencia a colistina si no que además crea una dependencia a este antibiótico. Sin embargo, este fenómeno de dependencia a colistina no ocurre si la resistencia se ha adquirido por modificación del LPS

Serinol-Based Benzoic Acid Esters as New Scaffolds for the Development of Adenovirus Infection Inhibitors: Design, Synthesis, and In Vitro Biological Evaluation

Over the years, human adenovirus (HAdV) has progressively been recognized as a significant viral pathogen. Traditionally associated with self-limited respiratory, gastrointestinal, and conjunctival infections, mainly in immunocompromised patients, HAdV is currently considered to be a pathogen presenting significant morbidity and mortality in both immunosuppressed and otherwise healthy individuals. Currently available therapeutic options are limited because of their lack of effectivity and related side effects. In this context, there is an urgent need to develop effective anti-HAdV drugs with suitable therapeutic indexes. In this work, we identified new serinol-derived benzoic acid esters as novel scaffolds for the inhibition of HAdV infections. A set of 38 compounds were designed and synthesized, and their antiviral activity and cytotoxicity were evaluated. Four compounds (13, 14, 27, and 32) inhibited HAdV infection at low micromolar concentrations (2.82–5.35 μM). Their half maximal inhibitory concentration (IC50) values were lower compared to that of cidofovir, the current drug of choice. All compounds significantly reduced the HAdV DNA replication process, while they did not block any step of the viral entry. Our results showed that compounds 13, 14, and 32 seem to be targeting the expression of the E1A early gene. Moreover, all four derivatives demonstrated a significant inhibition of human cytomegalovirus (HCMV) DNA replication. This new scaffold may represent a potential tool useful for the development of effective anti-HAdV drugs.This work has been supported by Ministerio de Ciencia, Innovación y Universidades, Plan Estatal 2017-2020 Retos-Proyectos I+D+i (PID2019-104767RB-I00), Ministerio de Economı́a y Competitividad, Plan Estatal 2013-2016 Retos-Proyectos I + D + i (CTQ2016-78580-C2-2-R) and by Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economia, Industria y Competitividad, Spanish Network for Research in Infectious Diseases (REIPI RD16/0016/0009), cofinanced by European Development Regional Fund “A way to achieve Europe”, the Instituto de Salud Carlos III, Proyectos de Investigación en Salud (PI17/01055; PI18/01191) and Proyectos de Desarrollo Tecnológico en Salud (DTS17/00130), the Spanish Adenovirus Network (AdenoNet, BIO2015/68990-REDT), and the program “Nicolás Monardes” (C-0059-2018), Servicio Andaluz de Salud, Junta de Andalucía. M.V.-H. also thanks Ministerio de Economı́a y Competitividad, Plan Estatal 2013-2016 Excelencia I+D+i (CTQ2016-78703-P)

Acidic Urine pH and Clinical Outcome of Lower Urinary Tract Infection in Kidney Transplant Recipients Treated with Ciprofloxacin and Fosfomycin

Different factors, including antimicrobial resistance, may diminish the effectiveness of antibiotic therapy, challenging the management of post-transplant urinary tract infection (UTI). The association of acidic urine pH with microbiological and clinical outcomes was evaluated after fosfomycin or ciprofloxacin therapy in 184 kidney transplant recipients (KTRs) with UTI episodes by Escherichia coli (N = 115) and Klebsiella pneumoniae (N = 69). Initial urine pH, antimicrobial therapy, and clinical and microbiological outcomes, and one- and six-month follow-up were assessed. Fosfomycin was prescribed in 88 (76.5%) E. coli and 46 (66.7%) K. pneumoniae UTI episodes in the total cohort. When the urine pH ≤ 6, fosfomycin was prescribed in 60 (52.2%) E. coli and 29 (42.0%) K. pneumoniae. Initial urine pH ≤ 6 in E. coli UTI was associated with symptomatic episodes (8/60 vs. 0/55, p = 0.04) at one-month follow-up, with a similar trend in those patients receiving fosfomycin (7/47 vs. 0/41, p = 0.09). Acidic urine pH was not associated with microbiological or clinical cure in K. pneumoniae UTI. At pH 5, the ciprofloxacin MIC90 increased from 8 to >8 mg/L in E. coli and from 4 to >8 mg/L in K. pneumoniae. At pH 5, the fosfomycin MIC90 decreased from 8 to 4 mg/L in E. coli and from 512 to 128 mg/L in K. pneumoniae. Acidic urine is not associated with the microbiological efficacy of fosfomycin and ciprofloxacin in KTRs with UTI, but it is associated with symptomatic UTI episodes at one-month follow-up in E. coli episodes.This study has been funded by Instituto de Salud Carlos III, through the projects PI17/01405 and PI20/01255, by the Subdirección General de Evaluación y Fomento de la Investigación, Ministerio de Economía, Industria y Competitividad, US-1381501 US/JUNTA/FEDER, UE, by the Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y Competitividad, and the Spanish Network for Research in Infectious Diseases (REIPI, RD16/0016/0009) and co-funded by the European Union.Peer reviewe

SARS-CoV-2 viral load in nasopharyngeal swabs is not an independent predictor of unfavorable outcome

The aim was to assess the ability of nasopharyngeal SARS-CoV-2 viral load at frst patient’s hospital evaluation to predict unfavorable outcomes. We conducted a prospective cohort study including 321 adult patients with confrmed COVID-19 through RT-PCR in nasopharyngeal swabs. Quantitative Synthetic SARS-CoV-2 RNA cycle threshold values were used to calculate the viral load in log10 copies/mL. Disease severity at the end of follow up was categorized into mild, moderate, and severe. Primary endpoint was a composite of intensive care unit (ICU) admission and/or death (n= 85, 26.4%). Univariable and multivariable logistic regression analyses were performed. Nasopharyngeal SARS-CoV-2 viral load over the second quartile (≥7.35 log10 copies/mL, p = 0.003) and second tertile (≥ 8.27 log10 copies/mL, p = 0.01) were associated to unfavorable outcome in the unadjusted logistic regression analysis. However, in the fnal multivariable analysis, viral load was not independently associated with an unfavorable outcome. Five predictors were independently associated with increased odds of ICU admission and/or death: age≥ 70 years, SpO2, neutrophils > 7.5 × ­103 /µL, lactate dehydrogenase≥ 300 U/L, and C-reactive protein≥ 100 mg/L. In summary, nasopharyngeal SARS-CoV-2 viral load on admission is generally high in patients with COVID-19, regardless of illness severity, but it cannot be used as an independent predictor of unfavorable clinical outcome

SARS-CoV-2 RNAemia is associated with severe chronic underlying diseases but not with nasopharyngeal viral load

Supported by Plan Nacional de I + D + i 2013–2016 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y Competitividad, Spanish Network for Research in Infectious Diseases (REIPI, RD16/0016/0001, RD16/0016/0005, RD16/0016/0007, RD16/0016/0009, RD16/0016/0010, R D16/0016/0013) cofinanced by European Development Regional Fund “A way to achieve Europe”, Operative program Intelligent Growth 2014–2020. JSC and EC received grants from the Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación, Proyectos de Investigación sobre el SARSCoV-2 y la enfermedad COVID-19 ( COV20/00580 ; COV20/00370 ). J.S.C. is a researcher belonging to the program “Nicolás Monardes” (C-0059–2018), Servicio Andaluz de Salud, Junta de Andalucía, Spain

Impact of SARS-CoV-2 RNAemia and other risk factors on long-COVID: A prospective observational multicentre cohort study

As the COVID-19 pandemic has progressed, long-COVID has emerged as a major problem that poses a significant challenge for attending physicians and health care policy makers. Therefore, we read with much interest the recently published unicentre study in the Journal of Infection by Righi et al.,1 carried out on 465 adult COVID-19 patients (235 [50.5%] hospital-admitted) followed-up during nine months, concluding that those with advanced age, intensive care unit (ICU) admission, and multiple symptoms at onset were more likely to have long-term COVID-19 symptoms, with negative impact on physical and mental wellbeing. Other studies have found that female gender, age, longer hospital stay, pre-existing hypertension, cardiovascular disease, diabetes, chronic obstructive pulmonary disease, smoking, obesity, and chronic alcoholism increase the likelihood of long-COVID.2,3 It is known that SARS-CoV-2 RNAemia is a predictor of COVID-19 severity and in-hospital complications.4,5 However, to the best of our knowledge, only two studies have assessed, up to one or three months after the acute COVID-19 onset, whether SARS-CoV-2 RNAemia may have an impact on long-COVID,6,7 both finding that RNAemia at presentation might predict the persistence of symptoms. However, these studies did not provide information regarding long-COVID symptoms nor the association with SARS-CoV-2 RNAemia beyond three months, and could not differentiate between “true” long-COVID and the convalescence phase of the SARS-CoV-2 infection.A.R. has received a predoctoral research grant from the Instituto de Salud Carlos III, Spanish Ministry of Science, Innovation and Universities, (PFIS grant FI18/00183). G.A.A. reports a predoctoral research grant from the 201808-10 project, funded by La Marató de TV3. This study was supported by the Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y Competitividad, the Spanish Network for Research in Infectious Diseases (REIPI, RD16/0016/0001, RD16/0016/0005, RD16/0016/0009, RD16/0016/0013)-co-financed by the European Development Regional Fund, A way to achieve Europe, Operative program Intelligent Growth 2014-2020, and the Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC) [CB21/13/00009; CB21/13/00006], Madrid, Spain. J.S.C. and E.C. received grants from the Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación, Proyectos de Investigación sobre el SARS-CoV-2 y la enfermedad COVID-19 (COV20/00580; COV20/00370). J.S.C. is a researcher belonging to the program “Nicolás Monardes” (C-0059–2018), Servicio Andaluz de Salud, Junta de Andalucía, Spain. Samples and data from patients included in this study from the Hospital Universitario Cruces (Bizkaia, Spain) were provided by the Basque Biobank (www.biobancovasco.org) and were processed following standard operation procedures with appropriate approval of the Ethical and Scientific Committees.Peer reviewe

SARS-CoV-2 viral load in nasopharyngeal swabs is not an independent predictor of unfavorable outcome

The aim was to assess the ability of nasopharyngeal SARS-CoV-2 viral load at first patient’s hospital evaluation to predict unfavorable outcomes. We conducted a prospective cohort study including 321 adult patients with confirmed COVID-19 through RT-PCR in nasopharyngeal swabs. Quantitative Synthetic SARS-CoV-2 RNA cycle threshold values were used to calculate the viral load in log10 copies/mL. Disease severity at the end of follow up was categorized into mild, moderate, and severe. Primary endpoint was a composite of intensive care unit (ICU) admission and/or death (n = 85, 26.4%). Univariable and multivariable logistic regression analyses were performed. Nasopharyngeal SARS-CoV-2 viral load over the second quartile (≥ 7.35 log10 copies/mL, p = 0.003) and second tertile (≥ 8.27 log10 copies/mL, p = 0.01) were associated to unfavorable outcome in the unadjusted logistic regression analysis. However, in the final multivariable analysis, viral load was not independently associated with an unfavorable outcome. Five predictors were independently associated with increased odds of ICU admission and/or death: age ≥ 70 years, SpO2, neutrophils > 7.5 × 103/µL, lactate dehydrogenase ≥ 300 U/L, and C-reactive protein ≥ 100 mg/L. In summary, nasopharyngeal SARS-CoV-2 viral load on admission is generally high in patients with COVID-19, regardless of illness severity, but it cannot be used as an independent predictor of unfavorable clinical outcome

Efficacy of dual carbapenem treatment in a murine sepsis model of infection due to carbapenemase-producing Acinetobacter baumannii

[Objectives] To evaluate the in vivo efficacy of a dual carbapenem combination containing imipenem plus meropenem against carbapenem-resistant Acinetobacter baumannii producing carbapenemases OXA-23 or OXA-58.[Methods] An experimental model of peritonitis using C57BL/6J female mice was developed and the minimum lethal doses were calculated for infections due to OXA-23 or OXA-58 producers of A. baumannii clinical isolates. The efficacies of the carbapenems in monotherapy and in combination were tested.[Results] Meropenem was better than imipenem in mice infected with either of the carbapenem-resistant A. baumannii (CRAb) strains. The combination of meropenem plus imipenem significantly improved the clearance of CRAbs from spleen compared with non-treated groups. The carbapenem-containing combination was better than imipenem for treating mice infected with both carbapenemase producers. In blood, the carbapenem combination significantly decreased the bacterial load of the OXA-23 producers compared with imipenem or meropenem used in monotherapy.[Conclusions] These results suggest that dual carbapenem combination could be an option for the treatment of infections due to carbapenemase-producing A. baumannii such as OXA-23 and OXA-58 producers.This study was carried out as part of our routine work. Authors from the Institute of Biomedicine of Seville, Seville, Spain, are supported by Plan Nacional de I + D+i 2013–2016 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y Competitividad, Spanish Network for Research in Infectious Diseases (REIPI RD16/0016/0009)—co-financed by European Development Regional Fund A way to achieve Europe, Operative programme Intelligent Growth 2014–2020. T.C.C. is supported by the V Plan Propio of the University of Seville (USE-19631-N). M.E.P.I. is supported by the programme ‘Nicolás Monardes’ (C1-0038–2019), Servicio Andaluz de Salud, Junta de Andalucía, Spain.Peer reviewe

Phenotypic changes associated with Colistin resistance due to Lipopolysaccharide loss in Acinetobacter baumannii

Acinetobacter baumannii can acquire resistance to colistin via complete loss of lipopolysaccharide (LPS) biosynthesis due to mutations in the lpxA, lpxC and lpxD genes. However, although colistin is increasingly being used for the treatment of multidrug resistant infections, very few A. baumannii clinical isolates develop colistin resistance through loss of LPS biosynthesis. This may suggest that LPS loss affects virulence traits that play a role in the transmission and pathogenesis of A. baumannii. In this study we characterize multiple virulence phenotypes of colistin resistant, LPS-deficient derivatives of the ATCC 19606 strain and five multidrug resistant clinical isolates and their colistin resistant, LPS-deficient derivatives. Our results indicate that LPS loss results in growth defects compared to the parental strain in vitro both in laboratory media and human serum (competition indices of 0.58 and 7.0 × 10−7, respectively) and reduced ability to grow and disseminate in vivo (competition index 6.7 × 10−8). Infection with the LPS-deficient strain resulted in lower serum levels of pro-inflammatory cytokines TNF-α and IL-6 compared to the parent strain, and was less virulent in a mouse model of disseminated sepsis. LPS loss also significantly affected biofilm production, surface motility, growth under iron limitation and susceptibility to multiple disinfectants used in the clinical setting. These results demonstrate that LPS loss has a significant effect on multiple virulence traits, and may provide insight into the low incidence of colistin resistant strains lacking LPS that have been reported in the clinical setting