Elevated complement C3 and increased CD8 and type 1 helper lymphocyte T populations in patients with post-COVID-19 condition.

BACKGROUND: Biological markers associated to post-COVID-19 condition (PCC) have not been clearly identified. METHODS: Eighty-two patients attending our post-COVID-19 outpatient clinic were recruited and classified as fully recovered (40.2%) or presenting with PCC (59.8%). Clinical and radiological data, laboratory markers, cytokines, and lymphocyte populations were analyzed. RESULTS: Median number of days after hospitalization was 78.5 [p25-p75: 60-93] days. PCC was significantly more frequent in women, in patients with a previously critical COVID-19, and in those with two or more comorbidities. No differences were found in lymphocyte counts, ferritin, C-reactive protein, D-dimer or sCD25, IL-1ß, IL-1Ra, IL-6, CXCL8, IL-17A, IL-18, IL-22, IFN-γ, TNF-α, and IL-10 cytokines levels. PCC patients showed significantly higher levels of complement factor C3 than fully recovered patients: median C3 128 mg/dL [p25-p75:107-135] vs 111 mg/dL [p25-p75: 100-125] (p =.005), respectively. In the flow cytometry assessment of peripheral blood lymphocyte subpopulations, PCC patients showed significantly increased CD8 populations compared to fully recovered patients: median CD8: 529 [p25-p75: 384-683] vs 370/mm3 [p25-p75:280-523], p =.007. When type 1, 2, 17/22, and 17.1 helper and follicular T lymphocyte subpopulations were analyzed, the frequency of Th1 was significantly higher in PCC patients compared to fully recovered patients (30% vs 38.5%, p =.028). CONCLUSION: Patients with a post-COVID-19 condition showed significantly increased immunological parameters of inflammation (complement factor C3 and CD8 and Th1 T lymphocyte populations) compared to fully recovered patients. These parameters could be used as biological markers of this condition.

Hyperinflammatory State and Low T1 Adaptive Immune Response in Severe and Critical Acute COVID-19 Patients.

Background: A better understanding of COVID-19 immunopathology is needed to identify the most vulnerable patients and improve treatment options. Objective: We aimed to identify immune system cell populations, cytokines, and inflammatory markers related to severity in COVID-19. Methods: 139 hospitalized patients with COVID-19-58 mild/moderate and 81 severe/critical-and 74 recovered patients were included in a prospective longitudinal study. Clinical data and blood samples were obtained on admission for laboratory markers, cytokines, and lymphocyte subsets study. In the recovered patients, lymphocyte subsets were analyzed 8-12 weeks after discharge. Results: A National Early Warning Score 2 >2 (OR:41.4; CI:10.38-167.0), ferritin >583 pg/mL (OR:16.3; CI: 3.88-69.9), neutrophil/lymphocyte ratio >3 (OR: 3.5; CI: 1.08-12.0), sIL-2rα (sCD25) >512 pg/mL (OR: 3.3; CI: 1.48-7.9), IL-1Ra >94 pg/mL (OR: 3.2; IC: 1.4-7.3), and IL-18 >125 pg/mL (OR: 2.4; CI: 1.1-5.0) were associated with severe/critical COVID-19 in the multivariate models used. Lower absolute values of CD3, CD4, CD8, and CD19 lymphocytes together with higher frequencies of NK cells, a CD4 and CD8 activated (CD38+HLA-DR+) memory T cell and effector memory CD45RA+ (EMRA) phenotype, and lower T regulatory cell frequencies were found in severe/critical patients relative to mild/moderate and recovered COVID-19 patients. A significant reduction in Th1, Tfh1, and Tc1 with higher Th2, Tfh2, Tc2, and plasma cell frequencies was found in the most severe cases. Conclusion: A characteristic hyperinflammatory state with significantly elevated neutrophil/lymphocyte ratio and ferritin, IL-1Ra, sIL-2rα, and IL-18 levels together with a "low T1 lymphocyte signature" was found in severe/critical COVID-19 patients.

Predictive Immunological, Virological, and Routine Laboratory Markers for Critical COVID-19 on Admission.

BACKGROUND: Early identification of COVID-19 patients at risk of critical illness is a challenging endeavor for clinicians. We aimed to establish immunological, virological, and routine laboratory markers, which, in combination with clinical information, may allow identifying such patients. METHODS: Blood tests to measure neutrophil/lymphocyte ratio (NLR) and levels of ferritin, CRP, D-dimer, complement components (C3 and C4), cytokines, and lymphocyte subsets, as well as SARS-Cov-2 RT-PCR tests, were performed in COVID-19-confirmed cases within 48 hours of admission. RT-PCR cycle threshold (Ct) values from oropharyngeal or nasopharyngeal swabs were determined on the day of admission. Symptom severity was categorized as mild (grade 1), severe (grade 2), or critical (grade 3). RESULTS: Of 120 patients who were included, 49 had mild, 32 severe, and 39 critical COVID-19. Levels of ferritin >370 ng/mL (OR 16.4, 95% CI 5.3-50.8), D-dimer >440 ng/mL (OR 5.45, 95% CI 2.36-12.61), CRP >7.65 mg/dL (OR 11.54, 95% CI 4.3-30.8), NLR >3.77 (OR 13.4, 95% CI 4.3-41.1), IL-6 >142.5 pg/mL (OR 8.76, 95% CI 3.56-21.54), IL-10 >10.8 pg/mL (OR 16.45, 95% CI 5.32-50.81), sIL-2rα (sCD25) >804.5 pg/mL (OR 14.06, 95% CI 4.56-43.28), IL-1Ra >88.4 pg/mL (OR 4.54, 95% CI 2.03-10.17), and IL-18 >144 pg/mL (OR 17.85, 95% CI 6.54-48.78) were associated with critical COVID-19 in the univariate age-adjusted analysis. This association was confirmed in the multivariate age-adjusted analysis only for ferritin, CRP, NLR, IL-10, sIL-2rα, and IL-18. T, B, and NK cells were significantly decreased in critical patients. SARS-CoV-2 was not detected in blood except in 3 patients who had indeterminate results. RT-PCR Ct values from oropharyngeal or nasopharyngeal swabs on admission were not related to symptom severity. CONCLUSION: Ferritin, D-dimer, CRP, NLR, cytokine (IL-18 and IL-10), and cytokine receptor (IL-6, IL1-Ra, and sCD25) test results combined with clinical data can contribute to the early identification of critical COVID-19 patients.

Daptomycin Plus Fosfomycin Versus Daptomycin Alone for Methicillin-resistant Staphylococcus aureus Bacteremia and Endocarditis: A Randomized Clinical Trial.

BACKGROUND: We aimed to determine whether daptomycin plus fosfomycin provides higher treatment success than daptomycin alone for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia and endocarditis. METHODS: A randomized (1:1) phase 3 superiority, open-label, and parallel group clinical trial of adult inpatients with MRSA bacteremia was conducted at 18 Spanish hospitals. Patients were randomly assigned to receive either 10 mg/kg of daptomycin intravenously daily plus 2 g of fosfomycin intravenously every 6 hours, or 10 mg/kg of daptomycin intravenously daily. Primary endpoint was treatment success 6 weeks after the end of therapy. RESULTS: Of 167 patients randomized, 155 completed the trial and were assessed for the primary endpoint. Treatment success at 6 weeks after the end of therapy was achieved in 40 of 74 patients who received daptomycin plus fosfomycin and in 34 of 81 patients who were given daptomycin alone (54.1% vs 42.0%; relative risk, 1.29 [95% confidence interval, .93-1.8]; P = .135). At 6 weeks, daptomycin plus fosfomycin was associated with lower microbiologic failure (0 vs 9 patients; P = .003) and lower complicated bacteremia (16.2% vs 32.1%; P = .022). Adverse events leading to treatment discontinuation occurred in 13 of 74 patients (17.6%) receiving daptomycin plus fosfomycin, and in 4 of 81 patients (4.9%) receiving daptomycin alone (P = .018). CONCLUSIONS: Daptomycin plus fosfomycin provided 12% higher rate of treatment success than daptomycin alone, but this difference did not reach statistical significance. This antibiotic combination prevented microbiological failure and complicated bacteremia, but it was more often associated with adverse events. CLINICAL TRIALS REGISTRATION: NCT01898338.

Ceftolozane/tazobactam for the treatment of multidrug resistant Pseudomonas aeruginosa: experience from the Balearic Islands.

A prospective, descriptive observational study of consecutive patients treated with ceftolozane/tazobactam in the reference hospital of the Balearic Islands (Spain), between May 2016 and September 2017, was performed. Demographic, clinical, and microbiological variables were recorded. The later included resistance profile, molecular typing, and whole genome sequencing of isolates showing resistance development. Fifty-eight patients were treated with ceftolozane/tazobactam. Thirty-five (60.3%) showed respiratory tract infections, 21 (36.2%) received monotherapy, and 37 (63.8%) combined therapy for ≥ 72 h, mainly with colistin (45.9%). In 46.6% of the patients, a dose of 1/0.5 g/8 h was used, whereas 2/1 g/8 h was used in 41.4%. In 56 of the cases (96.6%), the initial Pseudomonas aeruginosa isolates recovered showed a multidrug resistant (MDR) phenotype, and 50 of them (86.2%) additionally met the extensively drug resistant (XDR) criteria and were only susceptible colistin and/or aminoglycosides (mostly amikacin). The epidemic high-risk clone ST175 was detected in 50% of the patients. Clinical cure was documented in 37 patients (63.8%) and resistance development in 8 (13.8%). Clinical failure was associated with disease severity (SOFA), ventilator-dependent respiratory failure, XDR profile, high-risk clone ST175, negative control culture, and resistance development. In 6 of the 8 cases, resistance development was caused by structural mutations in AmpC, including some mutations described for the first time in vivo, whereas in the other 2, by mutations in OXA-10 leading to the extended spectrum OXA-14. Although further clinical experience is still needed, our results suggest that ceftolozane/tazobactam is an attractive option for the treatment of MDR/XDR P. aeruginosa infections.

Características clínicas de las infecciones respiratorias agudas causadas por los virus parainfluenza 1-4 en adultos / Clinical characteristics of acute respiratory infections caused by parainfluenzavirus 1-4 in adults

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Infección respiratoria aguda causada por el metapneumovirus humano: análisis de 39 casos / Acute respiratory infection caused by the human metapneumovirus: Analysis of 39 cases

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Safe Reduction in CD4 Cell Count Monitoring in Stable, Virally Suppressed Patients With HIV Infection or HIV/Hepatitis C Virus Coinfection.

BACKGROUND: It has been suggested that routine CD4 cell count monitoring in human immunodeficiency virus (HIV)-monoinfected patients with suppressed viral loads and CD4 cell counts >300 cell/µL could be reduced to annual. HIV/hepatitis C virus (HCV) coinfection is frequent, but evidence supporting similar reductions in CD4 cell count monitoring is lacking for this population. We determined whether CD4 cell count monitoring could be reduced in monoinfected and coinfected patients by estimating the probability of maintaining CD4 cell counts ≥200 cells/µL during continuous HIV suppression. METHODS: The PISCIS Cohort study included data from 14 539 patients aged ≥16 years from 10 hospitals in Catalonia and 2 in the Balearic Islands (Spain) since January 1998. All patients who had at least one period of 6 months of continuous HIV suppression were included in this analysis. Cumulative probabilities with 95% confidence intervals were calculated using the Kaplan-Meier estimator stratified by the initial CD4 cell count at the period of continuous suppression initiation. RESULTS: A total of 8695 patients were included. CD4 cell counts fell to <200 cells/µL in 7.4% patients, and the proportion was lower in patients with an initial count >350 cells/µL (1.8%) and higher in those with an initial count of 200-249 cells/µL (23.1%). CD4 cell counts fell to <200 cells/µL in 5.7% of monoinfected and 11.1% of coinfected patients. Of monoinfected patients with an initial CD4 cell count of 300-349 cells/µL, 95.6% maintained counts ≥200 cells/µL. In the coinfected group with the same initial count, this rate was lower, but 97.6% of coinfected patients with initial counts >350 cells/µL maintained counts ≥200 cells/µL. CONCLUSIONS: From our data, it can be inferred that CD4 cell count monitoring can be safely performed annually in HIV-monoinfected patients with CD4 cell counts >300 cells/µL and HIV/HCV-coinfected patients with counts >350 cells/µL.

Infecciones respiratorias agudas por bocavirus humanos en la población adulta ¿una rareza? / Acute respiratory infections by human bocavirus in the adult population. Really unfrequent?

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Clinical progression of severely immunosuppressed HIV-infected patients depends on virological and immunological improvement irrespective of baseline status.

OBJECTIVES: The aim of this study was to analyse factors associated with progression to AIDS/death in severely immunosuppressed HIV-infected patients receiving ART. METHODS: This study included naive patients from the PISCIS Cohort with CD4 <200 cells/mm(3) at enrolment and who initiated ART consisting of two nucleoside analogues plus either a PI or an NNRTI between 1998 and 2011. The PISCIS Cohort is a multicentre, observational study of HIV-infected individuals aged >18 years followed at 14 participating hospitals in Catalonia and the Balearic Islands (Spain). Clinical and laboratory parameters were assessed every 3-4 months during follow-up. Cox regression models were used to assess the effect of CD4 and viral load on the risk of progression to AIDS/death, adjusting for baseline variables and confounders. RESULTS: 2295 patients were included and, after 5 years, 69.9% reached CD4 ≥200 cells/mm(3), 64.4% had an undetectable viral load and 482 (21%) progressed to AIDS/death. The lowest rate of disease progression was found in patients who reached both immunological and viral responses during follow-up, regardless of their baseline situation (1.9% in baseline CD4 >100 cells/mm(3) and viral load <5 log copies/mL; 2.3% in baseline CD4 ≤100 cells/mm(3) and/or viral load >5 log copies/mL). Achieving a CD4 count ≥200 cells/mm(3) was the main predictor of decreased progression to AIDS/death. In those not reaching this CD4 threshold, virological response reduced disease progression by half. CONCLUSIONS: Even in the worse baseline scenario of CD4 ≤100 cells/mm(3) and high baseline viral loads, positive virological and immunological responses were associated with dramatic decreases in progression.

Influence of virulence genotype and resistance profile in the mortality of Pseudomonas aeruginosa bloodstream infections.

BACKGROUND: The type III secretion system (TTSS) is a major virulence determinant of Pseudomonas aeruginosa. The objective of this study was to determine whether the TTSS genotype is a useful prognostic marker of P. aeruginosa bacteremia mortality. We also studied the potential association between TTSS genotypes and multidrug-resistant (MDR) profiles, and how this interaction impacts the outcome of bloodstream infections. METHODS: We performed a post hoc analysis of a published prospective multicenter cohort of P. aeruginosa bloodstream infections. The impact in mortality of TTSS genotypes (exoS, exoT, exoU, and exoY genes) and resistance profiles was investigated. Cox regression analysis was used to control for confounding variables. RESULTS: Among 590 patients, the 30-day mortality rate was 30% (175 patients), and 53% of them died in the first 5 days (early mortality). The unadjusted probabilities of survival until 5 days was 31.4% (95% confidence interval [CI], 17.4%-49.4%) for the patients with exoU-positive isolates and 53.2% (95% CI, 44.6%-61.5%) for exoU-negative isolates (log rank P = .005). After adjustment for confounders, exoU genotype (adjusted hazard ratio [aHR], 1.90 [95% CI, 1.15-3.14]; P = .01) showed association with early mortality. In contrast, late (30-day) mortality was not influenced by TTSS genotype but was independently associated with MDR profiles (aHR,1.40 [95% CI, 1.01-1.94]; P = .04). Moreover, the exoU genotype (21% of all isolates) was significantly less frequent (13%) among MDR strains (particularly among extensively drug-resistant isolates, 5%), but was positively linked to moderately resistant (1-2 antipseudomonals) phenotypes (34%). CONCLUSIONS: Our results indicate that the exoU genotype, which is associated with specific susceptibility profiles, is a relevant independent marker of early mortality in P. aeruginosa bacteremia.

Differential body composition effects of protease inhibitors recommended for initial treatment of HIV infection: a randomized clinical trial.

BACKGROUND: It is unclear whether metabolic or body composition effects differ between protease inhibitor-based regimens recommended for initial treatment of human immunodeficiency virus (HIV) infection. METHODS: ATADAR is a phase 4, open-label, multicenter, randomized clinical trial. Stable antiretroviral-naive HIV-infected adults were randomly assigned to atazanavir/ritonavir 300/100 mg or darunavir/ritonavir 800/100 mg in combination with tenofovir/emtricitabine daily. Predefined endpoints were treatment or virological failure, drug discontinuation due to adverse effects, and laboratory and body composition changes at 96 weeks. RESULTS: At 96 weeks, 56 (62%) atazanavir/ritonavir and 62 (71%) darunavir/ritonavir patients remained free of treatment failure (estimated difference 8.2%; 95% confidence interval [CI], -.6 to 21.6) and 71 (79%) atazanavir/ritonavir and 75 (85%) darunavir/ritonavir patients remained free of virological failure (estimated difference 6.3%; 95% CI, -.5 to 17.6). Seven patients discontinued atazanavir/ritonavir and 5 discontinued darunavir/ritonavir due to adverse effects. Total and high-density lipoprotein cholesterol similarly increased in both arms, but there was a greater increase in triglycerides in the atazanavir/ritonavir arm. At 96 weeks, body fat (estimated difference 2862.2 gr; 95% CI, 726.7 to 4997.7; P = .0090), limb fat (estimated difference 1403.3 gr; 95% CI, 388.4 to 2418.2; P = .0071), and subcutaneous abdominal adipose tissue (estimated difference 28.4 cm(2); 95% CI, 1.9 to 55.0; P = .0362) increased more in the atazanavir/ritonavir arm than in darunavir/ritonavir arm. Body fat changes in the atazanavir/ritonavir arm were associated with higher insulin resistance. CONCLUSIONS: We found no major differences between atazanavir/ritonavir and darunavir/ritonavir in efficacy, clinically relevant side effects, or plasma cholesterol fractions. However, atazanavir/ritonavir led to higher triglycerides and more total and subcutaneous fat than darunavir/ritonavir. Also, fat gains with atazanavir/ritonavir were associated with insulin resistance. Clinical Trials Registration. NCT01274780.

Impact of prior virological failure and nucleos(t)ide genotypic resistance mutations on the efficacy of switching from ritonavir-boosted protease inhibitors to raltegravir.

BACKGROUND: The virological efficacy of switching from a ritonavir-boosted protease inhibitor (PI/r)- to a raltegravir (RAL)-containing regimen remains controversial according to the results of SWITCHMRK and SPIRAL studies. The aim of this analysis is to assess the impact of prior resistance mutations to nucleos(t)ides and other potential factors on the virological outcome. METHODS: This was a substudy of the prospective, open-label, multicentre SPIRAL study. Demographic, virological variables, prior episodes of virological failures (VF) and archived resistance mutations to nucleos(t)ides were identified from databases and its impact measured by genotypic sensitive scores (GSS) according to the genotypic resistance interpretation algorithm from the Stanford HIV Drug Resistance Database on outcome was analysed. RESULTS: Of 250 patients (128 RAL and 122 PI/r) included in the main SPIRAL study, 74 (30%) had previous VF with prior genotypic resistance tests (GRT). Median time of virological suppression prior to inclusion in SPIRAL study was 63.5 months. GSS for backbone nucleos(t)ides was <1 in 15/38 (39%) in the RAL arm and in 9/36 (25%) in the PI/r arm (P=0.13). Among those with nucleos(t)ides GSS <1, 0/15 (0%) in the RAL versus 2/9 (22%) in the PI/r arm developed VF (P=0.13). Moreover 0/11 subjects with null or residual (GSS≤0.5) backbone activity developed VF in the RAL arm. CONCLUSIONS: The 48-week virological efficacy of switching from a PI/r to RAL in subjects with long-term virological suppression was not compromised by a reduction of the nucleos(t)ide backbone activity.

La «intervención del tercer día»: análisis de los factores asociados al seguimiento de recomendaciones sobre la prescripción de antibióticos / 'Third day intervention': An analysis of the factors associated with following the recommendations on the prescribing of antibiotics

IINTRODUCCIÓN: Los programas de control de uso de antibióticos suelen incluir intervenciones basadas en recomendaciones no impositivas a los prescriptores. Interesa conocer los factores relacionados con la adherencia a las recomendaciones y su funcionamiento en la práctica real. MÉTODOS: Estudio multicéntrico, controlado y aleatorizado, realizado en 32 unidades de hospitalización. Especialistas en enfermedades infecciosas revisaron, alrededor del tercer día, las prescripciones de antibióticos, estableciendo recomendaciones. Describimos la implantación de la intervención, analizamos los factores asociados al seguimiento de las recomendaciones y el impacto de la intervención. RESULTADOS: Se realizaron 3.192 intervenciones. Las fuentes de información empleadas para la elaboración de las recomendaciones variaron significativamente entre los centros. En el 65% se recomendó alguna modificación del tratamiento: suspender los antibióticos (47%), modificar la vía de administración (26%), cambiar o variar el número de antibióticos (27%) y cambiar la dosis (5%). En el 75% se recomendó simplificar el tratamiento. La adherencia fue del 68%, con variaciones significativas entre los centros, y fue mayor cuando se recomendó ajuste de dosis o cambio de vía, durante el primer periodo del estudio y cuando las recomendaciones se realizaban, además de por escrito, verbalmente. No se pudo constatar impacto en el consumo de antibióticos ni en la incidencia de patógenos resistentes. CONCLUSIONES: Una elevada proporción de tratamientos antibióticos son susceptibles de modificación, generalmente hacia la simplificación. La adherencia a las recomendaciones fue elevada, aunque variable, dependiendo del centro, del tipo de recomendación, del periodo del estudio y de que la recomendación se realizara mediante un comentario verbal además de escrito

INTRODUCTION: Stewardship programs on the use of antibiotics usually include interventions based on non-compulsory recommendations for the prescribers. Factors related to the adherence to expert recommendations, and the implementation of these programmes in daily practice, are of interest. METHODS: A randomized, controlled, multicentre intervention study was performed in 32 hospitalization units. Antibiotic prescriptions were evaluated by an infectious disease specialist on the third day. We describe the implementation of the intervention, the factors associated with adherence to recommendations, and the impact of the intervention. RESULTS: A total of 3,192 interventions were carried out. Information sources used to prepare the recommendations varied significantly between centres. A modification was recommended in 65% of cases: withdrawal (47%), change in administration route (26%), change of drugs or number of antibiotics (27%), and change in dose (5%). Simplification of treatment accounted for 75% of all recommendations. Adherence was 68%, with significant differences between hospitals, and higher when the recommendations consisted of a dose adjustment or change of route, during the first intervention period, and also when recommendations were personally commented on, in addition to writing a note in the clinical chart. We did not find any reduction in antibiotic consumption or variation in the incidence of resistant pathogens. CONCLUSIONS: An important proportion of antibiotic prescriptions may be susceptible to improvement, most of them towards simplification. The adherence to the intervention was high, but significant variations at different centres were observed, depending on the type of recommendation, and the study period. Those recommendations that were personally commented on were more followed more than those only written

['Third day intervention': an analysis of the factors associated with following the recommendations on the prescribing of antibiotics]. / La "intervención del tercer día": análisis de los factores asociados al seguimiento de recomendaciones sobre la prescripción de antibióticos.

INTRODUCTION: Stewardship programs on the use of antibiotics usually include interventions based on non-compulsory recommendations for the prescribers. Factors related to the adherence to expert recommendations, and the implementation of these programmes in daily practice, are of interest. METHODS: A randomized, controlled, multicentre intervention study was performed in 32 hospitalization units. Antibiotic prescriptions were evaluated by an infectious disease specialist on the third day. We describe the implementation of the intervention, the factors associated with adherence to recommendations, and the impact of the intervention. RESULTS: A total of 3,192 interventions were carried out. Information sources used to prepare the recommendations varied significantly between centres. A modification was recommended in 65% of cases: withdrawal (47%), change in administration route (26%), change of drugs or number of antibiotics (27%), and change in dose (5%). Simplification of treatment accounted for 75% of all recommendations. Adherence was 68%, with significant differences between hospitals, and higher when the recommendations consisted of a dose adjustment or change of route, during the first intervention period, and also when recommendations were personally commented on, in addition to writing a note in the clinical chart. We did not find any reduction in antibiotic consumption or variation in the incidence of resistant pathogens. CONCLUSIONS: An important proportion of antibiotic prescriptions may be susceptible to improvement, most of them towards simplification. The adherence to the intervention was high, but significant variations at different centres were observed, depending on the type of recommendation, and the study period. Those recommendations that were personally commented on were more followed more than those only written.

Effect of adequate single-drug vs combination antimicrobial therapy on mortality in Pseudomonas aeruginosa bloodstream infections: a post Hoc analysis of a prospective cohort.

BACKGROUND: Empirical combination therapy is recommended for patients with known or suspected Pseudomonas aeruginosa (PA) infection as a means to decrease the likelihood of administering inadequate antimicrobial treatment, to prevent the emergence of resistance, and to achieve a possible additive or even synergistic effect. METHODS: We performed a post hoc analysis of patients with PA bloodstream infections from a published prospective cohort. Mortality was compared in patients treated with adequate empirical and definitive combination therapy (AECT, ADCT), and adequate empirical and definitive single-drug therapy (AESD, ADSD). Confounding was controlled by Cox regression analysis, and a propensity score for receiving AECT or ADCT was also used. RESULTS: The final cohort comprised 593 patients with a single episode of PA bacteremia. The 30-day mortality was 30% (176 patients); 76 patients (13%) died during the first 48 hours. The unadjusted probabilities of survival until day 30 were 69.4% (95% confidence interval [CI], 59.1-81.6) for the patients receiving AECT, 73.5% (95% CI, 68.4%-79.0%) for the AESD group, and 66.7% (95% CI, 61.2%-72.7%) for patients who received inadequate empirical therapy (P = .17, log-rank test). After adjustment for confounders, the AESD group (adjusted hazard ratio [AHR], 1.17; 95% CI, .70-1.96; P = .54) and patients who received ADSD (AHR, 1.34; 95% CI, .73-2.47; P = .35) showed no association with 30-day mortality compared with the AECT and ADCT groups, respectively. CONCLUSIONS: These results suggests that treatment with combination antimicrobial therapy did not reduce the mortality risk compared with single-drug therapy in PA bloodstream infections.