Susceptibility Provision Enhances Effective De-escalation (SPEED): utilizing rapid phenotypic susceptibility testing in Gram-negative bloodstream infections and its potential clinical impact

Abstract Objectives We evaluated the performance and time to result for pathogen identification (ID) and antimicrobial susceptibility testing (AST) of the Accelerate Pheno™ system (AXDX) compared with standard of care (SOC) methods. We also assessed the hypothetical improvement in antibiotic utilization if AXDX had been implemented. Methods Clinical samples from patients with monomicrobial Gram-negative bacteraemia were tested and compared between AXDX and the SOC methods of the VERIGENE® and Bruker MALDI Biotyper® systems for ID and the VITEK® 2 system for AST. Additionally, charts were reviewed to calculate theoretical times to antibiotic de-escalation, escalation and active and optimal therapy Results ID mean time was 21 h for MALDI-TOF MS, 4.4 h for VERIGENE® and 3.7 h for AXDX. AST mean time was 35 h for VITEK® 2 and 9.0 h for AXDX. For ID, positive percentage agreement was 95.9% and negative percentage agreement was 99.9%. For AST, essential agreement was 94.5% and categorical agreement was 93.5%. If AXDX results had been available to inform patient care, 25% of patients could have been put on active therapy sooner, while 78% of patients who had therapy optimized during hospitalization could have had therapy optimized sooner. Additionally, AXDX could have reduced time to de-escalation (16 versus 31 h) and escalation (19 versus 31 h) compared with SOC. Conclusions By providing fast and reliable ID and AST results, AXDX has the potential to improve antimicrobial utilization and enhance antimicrobial stewardship

Neutralizing Antibody Responses against Autologous and Heterologous Viruses in Acute versus Chronic Human Immunodeficiency Virus (HIV) Infection: Evidence for a Constraint on the Ability of HIV To Completely Evade Neutralizing Antibody Responses

Acute human immunodeficiency virus (HIV) infection is associated with the rapid development of neutralization escape mutations. The degree to which viral evolution persists in chronic infection has not been well characterized, nor is it clear if all patients develop high-level neutralization antibody escape. We therefore measured neutralizing antibody responses against autologous and heterologous viruses in a cohort of acutely and chronically infected subjects (n = 65). Neutralizing antibody responses against both autologous virus and heterologous viruses were lower among individuals with acute infection than among those with chronic infection. Among chronically infected individuals, there was a negative correlation between the level of neutralizing antibodies against autologous virus and the level of viremia. In contrast, there was a positive correlation between the level of neutralizing antibodies against a panel of heterologous viruses and the level of viremia. Viral evolution, as defined by the presence of higher neutralizing titers directed against earlier viruses than against contemporaneous viruses, was evident for subjects with recent infection but absent for those with chronic infection. In summary, neutralizing antibody responses against contemporaneous autologous viruses are absent in early HIV infection but can be detected at low levels in chronic infection, particularly among those controlling HIV in the absence of therapy. HIV replication either directly or indirectly drives the production of increasing levels of antibodies that cross-neutralize heterologous primary isolates. Collectively, these observations indicate that although HIV continuously drives the production of neutralizing antibodies, there may be limits to the capacity of the virus to evolve continuously in response to these antibodies. These observations also suggest that the neutralizing antibody response may contribute to the long-term control of HIV in some patients while protecting against HIV superinfection in most patients

Nephrotoxicity of Vancomycin in Combination with Beta-lactam Agents: Ceftolozane-tazobactam vs. Piperacillin-tazobactam

BACKGROUND: Vancomycin (VAN)-associated acute kidney injury (AKI) is increased when VAN is combined with certain beta-lactam (BL) such as piperacillin-tazobactam (TZP) but not had been evaluated with ceftolozane-tazobactam (C/T). We aim to investigate the AKI incidence of VAN in combination with C/T (VAN/C/T) compared to VAN in combination to TZP (VAN-TZP). METHOD: We conducted a multi-center observational comparative study across the United States. The primary analysis was a composite outcome of AKI: 1) RIFLE, 2) AKIN, or 3) VAN-induced-nephrotoxicity according to the consensus guidelines. Multivariable logistic regression analysis had been conducted to adjust for confounding variables and stratified Kaplan-Meir analysis to assess the time-to-nephrotoxicity between the two groups. RESULTS: We included (n = 90) VAN/C/T and (n = 284) VAN-TZP at an enrollment ratio of 3:1. The primary outcome occurred in 12.2% vs. 25.0% in the VAN-C/T and VAN-TZP groups, respectively (P = 0.011). After adjusting for confounding variables, VAN-TZP was associated with increased odds of AKI compared with patients receiving VAN-C/T; with an aOR of 3.308 [1.560-6.993]. Results of the stratified Kaplan-Meir with log-rank time-to-nephrotoxicity analysis indicate that time to AKI was significantly shorter among patients receiving VAN-TZP (P = 0.004). Cox proportional hazards analysis demonstrated that TZP was consistent with the primary analysis (P = 0.001). CONCLUSIONS: Collectively, our results suggest that the AKI is not likely to be related to tazobactam but rather to the piperacillin which is a component in the VAN-TZP combination but not the VAN-C/T