Risk of Acute Kidney Injury in Patients on Concomitant Vancomycin and Piperacillin-Tazobactam Compared to Those on Vancomycin and Cefepime.

BACKGROUND: Recent evidence suggests that among patients receiving vancomycin, receipt of concomitant piperacillin-tazobactam increases the risk of nephrotoxicity. Well-controlled, adequately powered studies comparing rates of acute kidney injury (AKI) among patients receiving vancomycin + piperacillin-tazobactam (VPT) compared to similar patients receiving vancomycin + cefepime (VC) are lacking. In this study we compared the incidence of AKI among patients receiving combination therapy with VPT to a matched group receiving VC. METHODS: A retrospective, matched, cohort study was performed. Patients were eligible if they received combination therapy for ≥48 hours. Patients were excluded if their baseline serum creatinine was >1.2mg/dL or they were receiving renal replacement therapy. Patients receiving VC were matched to patients receiving VPT based on severity of illness, intensive care unit status, duration of combination therapy, vancomycin dose, and number of concomitant nephrotoxins. The primary outcome was the incidence of AKI. Multivariate modeling was performed using Cox proportional hazards. RESULTS: A total of 558 patients were included. AKI rates were significantly higher in the VPT group than the VC group (81/279 [29%] vs 31/279 [11%]). In multivariate analysis, therapy with VPT was an independent predictor for AKI (hazard ratio = 4.27; 95% confidence interval, 2.73-6.68). Among patients who developed AKI, the median onset was more rapid in the VPT group compared to the VC group (3 vs 5 days P =< .0001). CONCLUSION: The VPT combination was associated with both an increased AKI risk and a more rapid onset of AKI compared to the VC combination.

Colistin Resistance in Carbapenem-Resistant Klebsiella pneumoniae: Laboratory Detection and Impact on Mortality.

Background: Polymyxins including colistin are an important "last-line" treatment for infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKp). Increasing use of colistin has led to resistance to this cationic antimicrobial peptide. Methods: A cohort nested within the Consortium on Resistance against Carbapenems in Klebsiella pneumoniae (CRACKLE) was constructed of patients with infection, or colonization with CRKp isolates tested for colistin susceptibility during the study period of December, 2011 to October, 2014. Reference colistin resistance determination as performed by broth macrodilution was compared to results from clinical microbiology laboratories (Etest) and to polymyxin resistance testing. Each patient was included once, at the time of their first colistin-tested CRKp positive culture. Time to 30-day in-hospital all-cause mortality was evaluated by Kaplan-Meier curves and Cox proportional hazard modeling. Results: In 246 patients with CRKp, 13% possessed ColR CRKp. ColR was underestimated by Etest (very major error rate = 35%, major error rate = 0.4%). A variety of rep-PCR strain types were encountered in both the ColS and the ColR groups. Carbapenem resistance was mediated primarily by blaKPC-2 (46%) and blaKPC-3 (50%). ColR was associated with increased hazard for in-hospital mortality (aHR 3.48; 95% confidence interval, 1.73-6.57; P < .001). The plasmid-associated ColR genes, mcr-1 and mcr-2 were not detected in any of the ColR CRKp. Conclusions: In this cohort, 13% of patients with CRKp presented with ColR CRKp. The apparent polyclonal nature of the isolates suggests de novo emergence of ColR in this cohort as the primary factor driving ColR. Importantly, mortality was increased in patients with ColR isolates.

Epidemiology of Acute Kidney Injury among Patients Receiving Concomitant Vancomycin and Piperacillin-Tazobactam: Opportunities for Antimicrobial Stewardship.

Despite their common use as an empirical combination therapy for the better part of a decade, there has been a recent association between combination therapy with vancomycin and piperacillin-tazobactam and high rates of acute kidney injury (AKI). The reasons for this increased association are unclear, and this analysis was designed to investigate the association. Retrospective cohort and case-control studies were performed. The primary objective was to assess if there is an association between extended-infusion piperacillin-tazobactam in combination with vancomycin and development of AKI. The secondary objectives were to identify risk factors for AKI in patients on the combination, regardless of infusion strategy, and to evaluate the impact of AKI on clinical outcomes. AKI occurred in 105/320 (33%) patients from the cohort receiving combination therapy with vancomycin and piperacillin-tazobactam, with similar rates seen in those receiving intermittent (53/160 [33.1%]) and extended infusions (52/160 [32.5%]) of piperacillin-tazobactam. Independent risk factors for AKI in the cohort included having a documented Gram-positive infection, the presence of sepsis, receipt of a vancomycin loading dose (odds ratio [OR], 2.22; 95% confidence interval [CI], 1.05 to 4.71), and receipt of any concomitant nephrotoxin (OR, 2.44; 95% CI, 1.41 to 4.22). For at-risk patients remaining on combination therapy, the highest rates of AKI occurred on days 4 (10.7%) and 5 (19.3%). The incidence of AKI in patients on combination therapy with vancomycin and piperacillin-tazobactam is high, occurring in 33% of patients. Receipt of piperacillin-tazobactam as an extended infusion did not increase this risk. Modifiable risk factors for AKI include receipt of a vancomycin loading dose, concomitant nephrotoxins, and longer durations of therapy.

Clinical and Molecular Epidemiology of Extended-Spectrum Beta-Lactamase-Producing Escherichia Coli Infections in Metro Detroit: Early Dominance of the ST-131 Clone.

INTRODUCTION: Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli infections have become endemic worldwide. We aimed to describe the molecular and clinical epidemiology of ESBL-producing E. coli infections during a period of rising global prevalence. METHODS: Three hundred sixty-nine consecutive ESBL-producing E. coli infections in Detroit from 2010-2011 were analyzed. Sequence typing (ST) and CH typing were performed. Clinical characteristics and outcomes were compared between patients infected with ST131 and non-ST131 isolates. RESULTS: Ninety-six percent of isolates were ST 131, and 78.6% of ST 131 isolates produced blaCTX-M-15. Median time to effective therapy was 48 h vs. 35 h (P = 0.38) in the ST131 vs. non-ST131 groups. Ninety-day mortality rates (8% vs. 8%, P = 1.0) were similar between the two groups. CONCLUSION: blaCTX-M-15 ST131 E. coli predominated in Detroit during an early period of global ST131 dissemination. Patients with ST131 E. coli infections had similar clinical outcomes to those with non-ST131 E. coli infections.

Surgical Site Infections Following Birmingham Hip Resurfacing.

The Birmingham Hip Resurfacing procedure (BHR) is metal-on-metal resurfacing procedure for hip arthritis. BHR was associated with low risk of surgical site infection (SSI; 0.6%). In addition to antimicrobials, superficial SSIs were treated with incision and drainage, whereas deep incisional or organ-space SSIs required removal of prosthesis. Infect Control Hosp Epidemiol 2016;1-4.

Impact of changes in the NHSN catheter-associated urinary tract infection (CAUTI) surveillance criteria on the frequency and epidemiology of CAUTI in intensive care units (ICUs).

The impact of the 2013 NHSN CAUTI definition on CAUTI rates was analyzed. A total of 107 CAUTI episodes were identified; 60 according to NHSN 2013 definitions only and 47 according to the 2012 and 2013 definitions. Physician-diagnosed "other infections" were more common among patients who had CAUTI only according to NHSN 2013 definitions (P<.001).