Risk factors for treatment failure in patients receiving ß-lactam/ß-lactamase inhibitor combinations for Enterobacteriaceae bloodstream infection: A retrospective, single-centre, cohort study.

The aim of this study was to investigate risk factors for treatment failure in patients receiving in vitro-active therapy with ß-lactam/ß-lactamase inhibitor (BL/BLI) for Enterobacteriaceae bloodstream infection (E-BSI). This was a retrospective, single-centre study of patients diagnosed with E-BSI at an Italian centre over a 4-year period. Exclusion criteria were age <18 years, clinical data unavailable, polymicrobial BSI, failure to receive in vitro-active therapy and death within 72 h from drawing the index blood culture. Patients who received BL/BLI as appropriate empirical and/or definitive therapy for ≥50% of the total treatment duration were selected. The primary endpoint was all-cause 30-day mortality. The secondary endpoint was 90-day relapse. Of 1319 eligible patients, 835 were selected. A total of 714 received BL/BLI as appropriate empirical therapy, of whom 522 remained on BL/BLI as definitive therapy and 192 shifted to another antibiotic for <50% of the treatment duration; 121 received BL/BLI as definitive therapy only. Non-susceptibility to extended-spectrum cephalosporins (NS-ESCs) was detected in 207 episodes (24.8%). All-cause 30-day mortality was 6.8%. In multivariate analysis adjusted for NS-ESC, independent predictors of mortality were Charlson comorbidity index, septic shock, Proteus spp. and CVC-related BSI, whilst urinary source was a protective factor. The 90-day relapse rate was 4.2%. Immunosuppression was the main independent predictor for relapse. BL/BLI was the most common antibiotic administered to patients with E-BSI in this cohort. Among patients appropriately treated with BL/BLI, failure rates were low and were primarily associated with underlying diseases, clinical severity at BSI onset and infection source.

The role of extended infusion ß-lactams in the treatment of bloodstream infections in patients with liver cirrhosis.

INTRODUCTION: Bloodstream infections (BSIs) in patients with liver cirrhosis are associated with significant morbidity and mortality. Early appropriated antibiotic treatment is essential for the correct management of these patients. Areas covered: This review covers several aspects of how the pharmacokinetic/pharmacodynamic behavior of antimicrobials may change in patients with liver cirrhosis. Common features of cirrhosis, including hypoproteinemia, third space expansion and impairment of renal function may alter drug distribution in patients receiving hydrophilic drugs like ß-lactams, which are often frontline agents. ß-lactams exhibit time-dependent pharmacodynamics and achieve maximal bacterial killing when serum drug and tissue concentrations exceed a multiple of the minimal inhibitory concentration (MIC) during the dosing interval (%fT>MIC). Administration of ß-lactams by extended infusion strategies improves the rate of this pharmacodynamic target attainment and has been associated with improved outcomes in several randomized trials in critically-ill patients. Expert commentary: Observational studies have suggested that cirrhotic patients have improved outcomes when beta-lactam therapy is administered by extended or continuum infusion. Given the multiple pathophysiological features of liver cirrhosis that impact antimicrobial behavior and the high incidence of multidrug resistance in this population, additional studies are needed to understand how cirrhosis affects the pharmacokinetics and pharmacodynamics of antibacterial therapy.

Differences in the rate of carbapenem-resistant Enterobacteriaceae colonisation or Clostridium difficile infection following frontline treatment with tigecycline vs. meropenem for intra-abdominal infections.

OBJECTIVES: We hypothesised that treatment with a tigecycline-based antimicrobial regimen for intra-abdominal infection (IAI) could be associated with lower rates of subsequent carbapenem-resistant Enterobacteriaceae (CRE) colonisation or Clostridium difficile infection (CDI) compared with a meropenem-based regimen. METHODS: We performed a retrospective, single-centre, matched (1:1) cohort analysis of all patients who received at least 5 days of empirical or targeted tigecycline (TIG)- or meropenem (MER)-based treatment regimens for IAI over a 50-month period. Patients with previous CRE colonisation and CDI were excluded. Risk factors for CRE and CDI were assessed with a Cox regression model that included treatment duration as a time-dependent variable. Thirty-day mortality was assessed with Kaplan-Meier curves. RESULTS: We identified 168 TIG-treated and 168 MER-treated patients. The cumulative incidence rate ratio of CDI was 10-fold lower in TIG-treated vs. MER-treated patients (incidence rate ratio [IRR] 0.10/1000 patient-days, 95%CI 0.002-0.72, P = 0.007), but similar incidence rates were found for CRE colonisation (IRR 1.39/1000 patient-days, 95%CI 0.68-2.78, P = 0.36). In a multivariate Cox regression model, the receipt of a TIG- vs. MER-based regimen was associated with significantly lower rates of CDI (HR 0.07, 95%CI 0.03-0.71, P = 0.02), but not CRE (HR 1.12, 95% CI 0.45-2.83, P = 0.80). All-cause 30-day mortality was similar in the two groups (P = 0.46). CONCLUSION: TIG-based regimens for IAI were associated with a 10-fold lower incidence of CDI compared with MER-based regimens, but there was no difference in the incidence of CRE colonisation.

Effect of combination therapy containing a high-dose carbapenem on mortality in patients with carbapenem-resistant Klebsiella pneumoniae bloodstream infection.

OBJECTIVES: To evaluate the impact of high-dose (HD) carbapenem-based combination therapy on clinical outcome in patients with monomicrobial carbapenem-resistant Klebsiella pneumoniae (CR-KP) bloodstream-infection (BSI). METHODS: Post hoc analysis of all adult patients with CR-KP BSI who were treated with a combination antibiotic regimen, collected over a six-year period in six large Italian teaching hospitals. To control for confounding effects of HD carbapenem combination on 14-day mortality, a multivariate Cox regression analysis was performed. Due to imbalances between patients, a propensity score for receiving HD carbapenem was added to the model. RESULTS: 595 patients with CR-KP BSI were analysed, 77% of isolates showed a carbapenem MIC ≥16 mg/L, 428 (71.9%) received HD carbapenem-based combination therapy. Overall, 127 patients (21.3%) died within 14 days after BSI onset. Multivariate analysis showed the Charlson comorbidity index (HR 1.31, 95%CI 1.20-1.43, P <0.001), septic shock at BSI onset (HR 3.14, 95%CI 2.19-4.50, P <0.001), and colistin-resistant strain (HR 1.52, 95%CI 1.02-2.24, P = 0.03) were independently associated with 14-day mortality, whereas admission to surgical ward (HR 0.44, 95%CI 0.25-0.78, P = 0.005) and HD carbapenem use (HR 0.69, 95%CI 0.47-1.00, P = 0.05) were protective factors. When adjusted for the propensity score, HD carbapenem use showed a greater protective effect (HR 0.64, 95%CI 0.43-0.95, P = 0.03). Stratifying the model for carbapenem MIC, the benefit of HD carbapenem was also observed for strains with carbapenem MIC ≥16 mg/L. CONCLUSIONS: In patients receiving combination therapy for CR-KP BSI, the use of HD carbapenem seems to be associated with better outcome, even in the presence of high-level carbapenem resistance.

Bloodstream infections in patients with liver cirrhosis.

Bloodstream infections are a serious complication in patients with liver cirrhosis. Dysregulated intestinal bacterial translocation is the predominant pathophysiological mechanism of infections in this setting. For this reason enteric Gram-negative bacteria are commonly encountered as the first etiological cause of infection. However, through the years, the improvement in the management of cirrhosis, the recourse to invasive procedures and the global spread of multidrug resistant pathogens have importantly changed the current epidemiology. Bloodstream infections in cirrhotic patients are characterized by high mortality rate and complications including metastatic infections, infective endocarditis, and endotipsitis (or transjugular intrahepatic portosystemic shunt-related infection). For this reason early identification of patients at risk for mortality and appropriated therapeutic management is mandatory. Liver cirrhosis can significantly change the pharmacokinetic behavior of antimicrobials. In fact hypoproteinaemia, ascitis and third space expansion and impairment of renal function can be translated in an unpredictable drug exposure.