PHILADELPHIA, PA—Higher rates of acute kidney injury (AKI) occurred in hospitalized patients receiving a combination of piperacillin-tazobactam and vancomycin than in those receiving vancomycin alone, piperacillin-tazobactam alone, daptomycin and piperacillin-tazobactam, or vancomycin and doripenem, according to a study presented at IDWeek 2014.

Additionally, the risk of AKI in patients receiving this common antimicrobial combination “was also associated with vasopressor use, more days of concurrent ACE inhibitor use, and slighter higher vancomycin troughs,” reported Morgan Scully, MD, of the University of Alabama School of Medicine and Huntsville Hospital, Huntsville, AL.

“More studies are needed to further explore how the concurrent use of vancomycin and piperacillin-tazobactam may be associated with an increased risk of AKI above the risk of either alone,” she added. “This is of particular value as the combination of the two drugs is a common hospital antibiotic regimen.”

A retrospective chart review of 391 patients admitted to a tertiary medical center over a 2-year period were analyzed to compare those receiving at least 48 hours of vancomycin, piperacillin-tazobactam, vancomycin and piperacillin-tazobactam, vancomycin and doripenem, and piperacillin-tazobactam and daptomycin for rates of AKI. All 5 groups had similar mean initial creatinine levels that ranged between 1–1.4mg/dL. The mean vancomycin trough level ranged between 14.53–15.88mcg/mL.

AKI, defined as a rise in creatinine by 0.5mg/dL or 50% above baseline, developed in 26 of 94 patients (28%) in the vancomycin and piperacillin-tazobactam group; 3 of 44 (7%) in the vancomycin alone group; 8 of 101 (8%) in the piperacillin-tazobactam alone group; 12 of 100 (12%) in the vancomycin-doripenem group; and 5 of 53 (9%) receiving piperacillin-tazobactam and daptomycin.

“There were differences in the percent of patients with diabetes,” Dr. Scully reported, “with the piperacillin-tazobactam and daptomycin group having the most (61%) and vancomycin having the least (23.25%).” The vancomycin and piperacillin-tazobactam group also had a higher percentage of patients requiring vasopressors, 29.78% compared with 16.28% of vancomycin, 12.87% of piperacillin-tazobactam, 10% of piperacillin-tazobactam and daptomycin, and only 1.9% of vancomycin and doripenem. Dr. Scully and colleagues noted that in each of the five groups, AKI was associated with a higher percentage of patients requiring vasopressors.

Patients in the vancomycin and piperacillin-tazobactam group who developed AKI had an average of 9.42 days with concurrent diuretic use compared with 2.72 days in those without AKI.