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Objectives To assess the impact of piperacillin/tazobactam MICs on in-hospital 30 day mortality in patients with third-generation cephalosporin-resistant Escherichia coli bloodstream infection treated with piperacillin/tazobactam, compared with those treated with carbapenems. Methods A multicentre retrospective cohort study was conducted in three large academic hospitals in Italy between 2018 and 2022. The study population comprised patients with monomicrobial third-generation cephalosporin-resistant E. coli bloodstream infection, who received either piperacillin/tazobactam or carbapenem therapy within 48 h of blood culture collection. The primary outcome was in-hospital 30 day all-cause mortality. A propensity score was used to estimate the likelihood of receiving empirical piperacillin/tazobactam treatment. Cox regression models were performed to ascertain risk factors independently associated with in-hospital 30 day mortality. Results Of the 412 consecutive patients included in the study, 51% received empirical therapy with piperacillin/tazobactam, while 49% received carbapenem therapy. In the propensity-adjusted multiple Cox model, the Pitt bacteraemia score [HR 1.38 (95% CI, 0.85–2.16)] and piperacillin/tazobactam MICs of 8 mg/L [HR 2.35 (95% CI, 1.35–3.95)] and ≥16 mg/L [HR 3.69 (95% CI, 1.86–6.91)] were significantly associated with increased in-hospital 30 day mortality, while the empirical use of piperacillin/tazobactam was not found to predict in-hospital 30 day mortality [HR 1.38 (95% CI, 0.85–2.16)]. Conclusions Piperacillin/tazobactam use might not be associated with increased mortality in treating third-generation cephalosporin-resistant E. coli bloodstream infections when the MIC is <8 mg/L. [ABSTRACT FROM AUTHOR]

We herein report on EUCAST RAST results for BCs consecutively collected between June 2019 and December 2019 that contained E. coli (n" 134) or K. pneumoniae (n" 66) isolates (Table S1, available as Supplementary data at JAC Online), of which 75 (37.5%) were phenotypically resistant to third-generation cephalosporins and/or carbapenems. In conclusion, we showed that the EUCAST RAST method affords an accurate and relatively easy means of testing antimicrobial susceptibility of E. coli and K. pneumoniae isolates directly in positive BC samples. Note that we tested only BC samples containing E. coli or K. pneumoniae, which are two species for which all DD plates could be read at the three timepoints. [Extracted from the article]

Objectives: To investigate the potential synergism of colistin in combination with N-acetylcysteine against Acinetobacter baumannii strains grown in planktonic phase or as biofilms.Methods: Sixteen strains were investigated, including nine colistin-susceptible (MIC range 0.5-1 mg/L) and seven colistin-resistant (MIC range 16-256 mg/L) strains. Synergism of colistin in combination with N-acetylcysteine was investigated by chequerboard assays. The activity of colistin/N-acetylcysteine combinations was further evaluated by time-kill assays with planktonic cultures (three colistin-resistant strains and one colistin-susceptible strain) and by in vitro biofilm models (three colistin-resistant and three colistin-susceptible strains).Results: Chequerboard assays revealed a relevant synergism of colistin/N-acetylcysteine combinations with all colistin-resistant strains, whereas no synergism was observed with colistin-susceptible strains. Time-kill assays showed a concentration-dependent potentiation of colistin activity by N-acetylcysteine against colistin-resistant strains, with eradication of the culture by combinations of N-acetylcysteine at 8000 mg/L plus colistin at 2 or 8 mg/L. A static effect during the first 8 h of incubation was demonstrated with the colistin-susceptible strain exposed to 0.25 × MIC colistin plus 8000 mg/L N-acetylcysteine. A remarkable antibiofilm synergistic activity of 8 mg/L colistin plus 8000 mg/L N-acetylcysteine was demonstrated with all colistin-resistant and colistin-susceptible strains. The effects were greater with colistin-resistant strains (marked reduction of viable biofilm cells was observed at sub-MIC colistin concentrations).Conclusions: N-acetylcysteine, at concentrations achievable by topical administration, was shown to revert the colistin-resistant phenotype in A. baumannii, and to exert a relevant activity against biofilms of colistin-susceptible and colistin-resistant A. baumannii strains. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "High-dose daptomycin for cardiac implantable electronic device-related infectiveendocarditis," in the November 28, 2011 issue of the journal.