Effect of Antibiotic Choice On ReNal Outcomes (ACORN)

Sepsis is a common condition associated with high mortality and morbidity. Antibiotics are an integral component of the management of patients with sepsis. Each hour delay in antibiotic administration in sepsis is associated with an increase in mortality. Clinical guidelines recommend early management bundles, including early broad-spectrum antibiotics, for patients with presumed sepsis in the emergency department and intensive care unit. Since the specific organism causing an infection is rarely known at clinical presentation, empiric broad-spectrum antibiotics are commonly prescribed. For patients at risk for resistant organisms, the most common regimens include vancomycin (to cover gram-positive organisms including methicillin-resistant Staphylococcus aureus) and an anti-pseudomonal cephalosporin or anti-pseudomonal penicillin (to cover gram-negative organisms including Pseudomonas). Cephalosporins and penicillins are beta-lactam antibiotics that act by inhibiting the synthesis of the peptidoglycan layer of bacterial cell walls. They are commonly used for a variety of infections including empiric broad spectrum coverage for sepsis and suspected nosocomial infections. Several cephalosporins and penicillins have anti-pseudomonal activity, including cefepime, a fourth-generation cephalosporin, ceftazidime, a third-generation cephalosporin, and piperacillin-tazobactam, an extended-spectrum penicillin with beta-lactamase inhibitor. Anti-pseudomonal penicillins are the preferred agents for empiric broad spectrum coverage at many centers, and piperacillin-tazobactam, specifically, has the added benefit of treating anaerobic organisms. Acute Kidney Injury (AKI) is a common complication of ICU admission. AKI is associated with a six to eight fold increase in mortality in ICU populations is therefore a common target of critical care trials. Sepsis is the most common cause of AKI and accounts for 40-50% of AKI in the intensive care unit (ICU). As the primary treatment for the underlying cause of sepsis, antibiotics are a critical treatment for acutely ill patients, but antibiotics may cause renal injury, and renally-cleared antibiotics may reach supratherapeutic levels in the setting of AKI. Vancomycin has long been associated with AKI. Recently, a number of retrospective observational analyses have examined a potential association between the concurrent administration of vancomycin and piperacillin-tazobactam and the development of AKI, compared with vancomycin alone. These data, however, are likely to be confounded by indication bias and studies evaluating whether piperacillin-tazobactam causes more AKI than other anti-pseudomonal antibiotics have been inconclusive. Based on this preliminary, observational data, however, some institutions have elected to change their preferred broad spectrum antibiotic regimens from one including an anti-pseudomonal penicillin to one including an anti-pseudomonal cephalosporin. However, others have argued against this approach given the lack of randomized trials comparing the relative efficacy and safety of the two agents as well as observational data suggesting that cephalosporins may be associated with neuro-toxicity. Tens of thousands of patients each year receive either anti-pseudomonal cephalosporins and penicillins, but no randomized trials have ever compared their relative effectiveness or safety. Each class of medications has been hypothesized to have toxicities that may be relevant for acutely ill patients. Because the relationship between antibiotic choice (anti-pseudomonal cephalosporins or anti-pseudomonal penicillins) and clinically relevant outcomes, such as AKI, are unknown, clinical trial data is urgently needed. Rigorous high-quality evidence that anti-pseudomonal cephalosporins, compared to anti-pseudomonal penicillins, decreases, increases or has no impact on the risk of AKI would have the potential to change the care received by thousands of acutely ill adults each year.