b Nafcillin and oxacillin are used interchangeably in clinical practice, yet few studies have evaluated the safety of these two agents. Our objective was to compare the differential tolerabilities of nafcillin and oxacillin among hospitalized patients. We conducted a retrospective cohort study of all patients who received 12 g/day of nafcillin or oxacillin for at least 24 h. Two hundred twentyfour patients were included. Baseline characteristics and comorbidities were similar among patients receiving nafcillin (n ‫؍‬ 160) and those receiving oxacillin (n ‫؍‬ 64). Hypokalemia, defined as a potassium level of <3.3 mmol/liter or <2.9 mmol/liter or as a >0.5-mmol/liter decrease from the baseline level, occurred more frequently among patients who received nafcillin (51%, 20%, and 56%, respectively) than among those who received oxacillin (17%, 3%, and 34%, respectively; P < 0.0001, P ‫؍‬ 0.0008, and P ‫؍‬ 0.005, respectively). By multivariate logistic regression analysis, receipt of nafcillin was an independent predictor of severe hypokalemia (odds ratio [OR] ‫؍‬ 6.74; 95% confidence interval [CI], 1.46 to 31.2; P ‫؍‬ 0.02). Rates of hepatotoxicity did not differ between groups; however, acute kidney injury occurred more commonly with nafcillin than with oxacillin (18% versus 6%; P ‫؍‬ 0.03). Overall, 18% of patients who received nafcillin discontinued therapy prematurely due to adverse events, compared to 2% of patients who received oxacillin (P ‫؍‬ 0.0004). Nafcillin treatment is associated with higher rates of adverse events and treatment discontinuation than oxacillin among hospitalized adult patients. These findings have important implications for patients in both inpatient and outpatient settings, particularly patients who require long-term therapy and cannot be monitored routinely. Future randomized controlled studies evaluating the efficacy, costs, and tolerability of nafcillin versus oxacillin are warranted.

We conducted a retrospective study to determine the risk factors associated with vancomycin-resistant enterococci (VRE) acquisition/infection in newly diagnosed acute myeloid leukemia and myelodysplastic syndrome patients undergoing chemotherapy with the 7 + 3 regimen of cytarabine and idarubicin. Although only 2.5% (6/235) patients were colonized with VRE on admission, 59% (134/229) of patients acquired VRE during their hospitalization. Multivariable analysis identified the use of intravenous vancomycin (p = .024; HR: 1.548) and cephalosporin (p = .009; HR: 1.596) as the risk factors for VRE acquisition. VRE infection developed in 14% (33/229) of patients, with bloodstream infections accounting for 82% (27/33) of cases. VRE infection occurred in 25/126 (20%) of the VRE-colonized patients, but only 8/103 (8%) of those who were not (p = .01). Our study provides the evidence for the role of intravenous cephalosporin and vancomycin in VRE acquisition and highlights the clinical significance of VRE colonization in these patients.

Rhabdomyolysis is a clinical syndrome associated with electrolyte abnormalities and myoglobinuria. Signs and symptoms of rhabdomyolysis include elevated creatinine phosphokinase (CPK) and aspartate transaminase (AST), muscle pain, urine discoloration, fatigue, nausea, vomiting and fever. 1 If untreated, rhabdomyolysis can lead to renal failure and death. 2 Rhabdomyolysis can occur as a result of traumatic injury or chemical causes. 1-3 Prior case reports describing fluoroquinolone-induced rhabdomyolysis occurred within the first week of fluoroquinolone initiation. 4-10 Most of these involved the co-administration of simvastatin and either ciprofloxacin or levofloxacin. 4,5,7-10 We report a rare case of delayed-onset acute rhabdomyolysis that coincided with initiation of levofloxacin in a patient on long-term atorvastatin. A literature search of articles published in English through August 2018 was conducted using PubMed to identify other publications on fluoroquinolone-induced rhabdomyolysis with and without concomitant statin therapy. The following search terms were used alone and in combination: rhabdomyolysis, fluoroquinolone, statin, levofloxacin, atorvastatin. Citations of included articles were also reviewed to identify additional publications. | C A S E DE SCRIP TI ONA 65-year-old white male presented to an outside hospital with complaints of right knee pain, swelling, subjective fevers, chills, and inability to bear weight in the setting of prior right total knee arthroplasty. He was started on vancomycin and aztreonam for empiric treatment of a right knee prosthetic joint infection and was subsequently transferred to our facility for surgical intervention. The

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BackgroundIncreasing evidence suggests that daptomycin (DAP) demonstrates in vitro synergy in combination with other anti-staphylococcal agents, including ceftaroline (CPT) and oxacillin (OXA), against MRSA. Nevertheless, optimal combinations remain undefined. Here, our objective was to compare DAP in combination with CPT or OXA against MRSA bloodstream isolates collected from patients with persistent bacteremia despite >7 days of vancomycin treatment.MethodsMinimum inhibitory concentrations (MICs) for DAP, CPT, and OXA were determined in duplicate by reference broth microdilution methods. We used time-kill analyses (TKA) to test free peak concentrations (fCmax) of DAP (8 µg/mL), CPT (16 µg/mL), and OXA (4 µg/mL) alone and in combination against 1 × 108 CFU/mL to simulate high-inocula infections. Bactericidal and synergistic activity were defined as a ≥3-log10 decrease in CFU/mL and >2-log10 decrease in CFU/mL in combination compared with the most active single agent, respectively, at 24 hours.ResultsA representative isolate was selected from 12 patients with persistent MRSA bacteremia. Median (range) MICs were 0.5 (0.5–1), 0.5 (0.5–1), and 64 (64–≥128) µg/mL for DAP, CPT, and OXA, respectively. By TKA (n = 5 isolates), median log-kills were −3.81, −1.90, and +1.99 log10CFU/mL for DAP, CPT, OXA, respectively. Corresponding rates of bactericidal activity were 80%, 20%, and 0%, respectively. In combination, median log-kills were −7.83 and −4.82 log10CFU/mL for DAP+CPT and DAP+OXA, respectively (P = 0.111; Figure 1). DAP was synergistic in combination with CPT or OXA against 80% and 60% of isolates, respectively. Median log-kills in combination with CPT or OXA were higher than DAP alone (P = 0.003 and P = 0.0497, respectively). At 24 hours, colony counts were below the lower limit of detection (50 CFU/mL) against 60% and 20% of isolates exposed to DAP+CPT or DAP+OXA, respectively.ConclusionAmong persistent MRSA bloodstream isolates, combinations of DAP + CPT or OXA demonstrates synergy and statistically greater killing effects in vitro at fCmax concentrations than DAP alone. Log-kills were greatest with DAP+CPT, which merits further validation in pre-clinical models. Disclosures All authors: No reported disclosures.

Background Candida parapsilosis fungemia typically occurs in patients with intravascular catheters or prosthetic devices. In 2017, we noted an increase in C. parapsilosis infective endocarditis (IE).MethodsWe retrospectively reviewed C. parapsilosis fungemia and IE from January 2015 to February 2018. Species were identified using MALDI-TOF, and confirmed by ITS sequencing.ResultsBetween 2010 and 2017, there was no increase in cases of C. parapsilosis fungemia (mean: 13/year), but there was a significant increase in C. parapsilosis IE (P = 0.048) (Figure 1). From January 2015 to February 2018, 22% (12/54) of C. parapsilosis fungemia was complicated by IE. Demographics of C. parapsilosis fungemia included: community-acquired infection (87%), presence of vascular catheters (80%), opiate noninjection drug use (non-IDU, 44%), IDU (20%), and presence of cardiac devices (18%). Ninety-one percent (49/54) of C. parapsilosis fungemia was caused by C. parapsilosis sensu strictu (Cpss); C. orthopsilosis and C. metapsilosis accounted for 4% (2/54) each (1 isolate could not be subtyped). Cpss, C. orthopsilosis, and C. metapsilosis accounted for 83% (10/12), 8% (1/12), and 8% (1/12) of IE, respectively. Ninety-two% (11/12) of C. parapsilosis IE was left-sided, and 33% (4/12) involved multiple valves. Risk factors for C. parapsilosis IE were past or active IDU (P < 0.001), community-acquired fungemia (P = 0.02), prosthetic heart valve (P = 0.01) or implanted cardiac device (P = 0.03). Receipt of an antibiotic within 30 days was a risk for C. parapsilosis fungemia without IE (P = 0.001). Median age for IE vs. fungemia was 38 vs. 57 years (P = 0.09). By multivariate logistic regression, IDU (P < 0.0001), prosthetic valve (P = 0.006) or implanted cardiac device (P = 0.04) were independent risks for C. parapsilosis IE. 70% (7/10), 20% (2/10), and 10% (1/10) of patients with IDU and C. parapsilosis IE primarily used heroin, buprenorphine/naltrexone, and cocaine, respectively. 50% (6/12) of patients with C. parapsilosis IE underwent surgery; most common initial AF regimens were caspofungin and amphotericin B. Nonsurgical patients were suppressed with long-term azole; one relapsed requiring surgery. Thirty-day and in-hospital mortality for patients with fungemia vs. IE were 32% vs. 17% and 26% vs. 17%, respectively.Conclusion C. parapsilosis IE has emerged at our center. Unique aspects of C. parapsilosis pathogenesis that may account for emergence are a propensity to colonize skin, adhere to prosthetic material and form biofilm. C. parapsilosis IE may be an under-appreciated consequence of IDU and opioid abuse. Disclosures All authors: No reported disclosures.