Association Between Social Vulnerability and Streptococcus pneumoniae Antimicrobial Resistance in US Adults.

BACKGROUND: Growing evidence indicates antimicrobial resistance disproportionately affects individuals living in socially vulnerable areas. This study evaluated the association between Streptococcus pneumoniae (SP) antimicrobial resistance (AMR) and the CDC/ATSDR Social Vulnerability Index (SVI) in the United States. METHODS: Adult patients ≥ 18 years with 30-day nonduplicate SP isolates from ambulatory/hospital settings from January 2011-December 2022 with zip codes of residence were evaluated across 177 facilities in the BD Insights Research Database. Isolates were identified as SP AMR if they were non-susceptible to ≥ 1 antibiotic class (macrolide, tetracycline, extended-spectrum cephalosporins, or penicillin). Associations between SP AMR and SVI score (overall and themes) were evaluated using generalized estimating equations with repeated measurements within county to account for within-cluster correlations. RESULTS: Of 8,008 unique SP isolates from 574 US counties across 39 states, the overall proportion of AMR was 49.9%. A significant association between socioeconomic status (SES) theme and SP AMR was detected with higher SES theme SVI score (indicating greater social vulnerability) associated with greater risk of AMR. On average, a decile increase of SES, indicating greater vulnerability, was associated with a 1.28% increased risk of AMR (95% confidence interval [CI], 0.61%, 1.95%; P=0.0002). A decile increase of household characteristic score was associated with a 0.81% increased risk in SP AMR (95% CI,0.13%, 1.49%; P=0.0197). There was no association between racial/ethnic minority status, housing type and transportation theme, or overall SVI score and SP AMR. CONCLUSIONS: SES and household characteristics were the SVI themes most associated with SP AMR.

Association of SARS-CoV-2 status and antibiotic-resistant bacteria with inadequate empiric therapy in hospitalized patients: a US multicenter cohort evaluation (July 2019 - October 2021).

BACKGROUND: Antibiotic usage and antibiotic resistance (ABR) patterns changed during the COVID-19 pandemic. Inadequate empiric antibiotic therapy (IET) is a significant public health problem and contributes to ABR. We evaluated factors associated with IET before and during the COVID-19 pandemic to determine the impact of the pandemic on antibiotic management. METHODS: This multicenter, retrospective cohort analysis included hospitalized US adults who had a positive bacterial culture (specified gram-positive or gram-negative bacteria) from July 2019 to October 2021 in the BD Insights Research Database. IET was defined as antibacterial therapy within 48 h that was not active against the bacteria. ABR results were based on susceptibility testing and reports from local facilities. Multivariate analysis was used to identify risk factors associated with IET in patients with any positive bacterial culture and ABR-positive cultures, including multidrug-resistant (MDR) bacteria. RESULTS: Of 278,344 eligible patients in 269 hospitals, 56,733 (20.4%) received IET; rates were higher in patients with ABR-positive (n = 93,252) or MDR-positive (n = 39,000) cultures (34.9% and 45.0%, respectively). Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2)-positive patients had significantly higher rates of IET (25.9%) compared with SARS-CoV-2-negative (20.3%) or not tested (19.7%) patients overall and in the ABR and MDR subgroups. Patients with ABR- or MDR-positive cultures had more days of therapy and longer lengths of stay. In multivariate analyses, ABR, MDR, SARS-CoV-2-positive status, respiratory source, and prior admissions were identified as key IET risk factors. CONCLUSIONS: IET remained a persistent problem during the COVID-19 pandemic and occurred at higher rates in patients with ABR/MDR bacteria or a co-SARS-CoV-2 infection.

A Multicenter Comparison of Prevalence and Predictors of Antimicrobial Resistance in Hospitalized Patients Before and During the Severe Acute Respiratory Syndrome Coronavirus 2 Pandemic.

Background: Antibacterial therapy is frequently used in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) without evidence of bacterial infection, prompting concerns about increased antimicrobial resistance (AMR). We evaluated trends in AMR before and during the SARS-CoV-2 pandemic. Methods: This multicenter, retrospective cohort analysis included hospitalized adults aged ≥18 years with >1-day inpatient admission and a record of discharge or death from 271 US facilities in the BD Insights Research Database. We evaluated rates of AMR events, defined as positive cultures for select gram-negative and gram-positive pathogens from any source, with nonsusceptibility reported by commercial panels before (1 July 2019-29 February 2020) and during (1 March 2020-30 October 2021) the SARS-CoV-2 pandemic. Results: Of 5 518 666 admissions evaluated, AMR rates per 1000 admissions were 35.4 for the prepandemic period and 34.7 for the pandemic period (P ≤ .0001). In the pandemic period, AMR rates per 1000 admissions were 49.2 for SARS-CoV-2-positive admissions, 41.1 for SARS-CoV-2-negative admissions, and 25.7 for patients untested (P ≤ .0001). AMR rates per 1000 admissions among community-onset infections during the pandemic were lower versus prepandemic levels (26.1 vs 27.6; P < .0001), whereas AMR rates for hospital-onset infections were higher (8.6 vs 7.7; P < .0001), driven largely by SARS-CoV-2-positive admissions (21.8). AMR rates were associated with overall antimicrobial use, rates of positive cultures, and higher use of inadequate empiric therapy. Conclusions: Although overall AMR rates did not substantially increase from prepandemic levels, patients tested for SARS-CoV-2 infection had a significantly higher rate of AMR and hospital-onset infections. Antimicrobial and diagnostic stewardship is key to identifying this high-risk AMR population.

Use of Novel Antibiograms to Determine the Need for Earlier Susceptibility Testing and Administration for New ß-Lactam/ß-Lactamase Inhibitors in the United States.

Antimicrobial resistance is a global public health threat, and gram-negative bacteria, such as Enterobacterales and Pseudomonas aeruginosa, are particularly problematic with difficult-to-treat resistance phenotypes. To reduce morbidity and mortality, a reduction in the time to effective antimicrobial therapy (TTET) is needed, especially among critically ill patients. The antibiogram is an effective clinical tool that can provide accurate antimicrobial susceptibility information and facilitate early antimicrobial optimization, decrease TTET, and improve outcomes such as mortality, hospital length of stay, and costs. Guidance is lacking on how to validate the susceptibility to new antibacterial agents. Commonly used traditional and combination antibiograms may not adequately assist clinicians in making treatment decisions. Challenges with the current susceptibility testing of new ß-lactam/ß-lactamase inhibitor combinations persist, impacting the appropriate antibacterial choice and patient outcomes. Novel antibiograms such as syndromic antibiograms that incorporate resistant gram-negative phenotypes and/or minimum inhibitory concentration distributions may assist in determining the need for earlier susceptibility testing or help define an earlier optimal use of the new ß-lactam/ß-lactamase inhibitors. The purpose of this review is to emphasize novel antibiogram approaches that are capable of improving the time to susceptibility testing and administration for new ß-lactam/ß-lactamase inhibitors so that they are earlier in a patient's treatment course.

Multicenter Cohort Study of Ceftaroline Versus Daptomycin for Treatment of Methicillin-Resistant Staphylococcus aureus Bloodstream Infection.

BACKGROUND: Observational data suggest ceftaroline may be effective for methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI), but comparative data with standard of care are limited. This analysis compares the outcomes of MRSA BSI treated with ceftaroline or daptomycin. METHODS: Multicenter, retrospective, observational cohort study of adult patients with MRSA BSI from 2010 to 2017. Patients treated with ≥72 hours of ceftaroline or daptomycin were included. Those clearing BSI before study drug and those with a pneumonia source were excluded. The primary outcome was composite treatment failure, defined as 30-day mortality, BSI duration ≥7 days on study drug, and 60-day MRSA BSI recurrence. Inverse probability of treatment weighted risk difference in composite failure between daptomycin and ceftaroline groups was computed and 15% noninferiority margin applied. RESULTS: Two hundred seventy patients were included; 83 ceftaroline and 187 daptomycin. Ceftaroline was noninferior to daptomycin with respect to composite failure (39% daptomycin, 32.5% ceftaroline; weighted risk difference, 7.0% [95% confidence interval, -5.0% to 19.0%]). No differences between treatment groups was observed for 30-day mortality or other secondary efficacy outcomes. Creatine phosphokinase elevation was significantly more common among daptomycin patients (5.3% vs 0%, P = .034). Rash was significantly more common among ceftaroline patients (10.8 vs 1.1%, P = .001). CONCLUSIONS: No difference in treatment failure or mortality was observed between MRSA BSI treated with ceftaroline or daptomycin. These data support future study of ceftaroline as a primary MRSA BSI treatment and current use of ceftaroline when an alternative to vancomycin and daptomycin is required.

Antimicrobial stewardship and antibiograms: importance of moving beyond traditional antibiograms.

The rapid evolution of resistance, particularly among Gram-negative bacteria, requires appropriate identification of patients at risk followed by administration of appropriate empiric antibiotic therapy. A primary tenet of antimicrobial stewardship programs (ASPs) is the establishment of empiric antibiotic recommendations for commonly encountered infections. An important tool in providing empiric antibiotic therapy recommendations is the use of an antibiogram. While the majority of institutions use a traditional antibiogram, ASPs have an opportunity to enhance antibiogram data. The authors provide the rationale for why ASPs should implement alternative antibiograms, and the importance of incorporating an antibiogram into clinical decision support systems with the goal of providing effective empiric antibiotic therapy.

Variable linezolid exposure and response and the role of therapeutic drug monitoring: Case series.

Two patients with normal renal function, yet each showed unexpected, supra- and subtherapeutic linezolid plasma concentrations resulting in toxicity and ineffective therapy, respectively. TDM helps to early identify and correct such excursions.

Towards precision medicine: Therapeutic drug monitoring-guided dosing of vancomycin and ß-lactam antibiotics to maximize effectiveness and minimize toxicity.

PURPOSE: The goal of this review is to explore the role of antimicrobial therapeutic drug monitoring (TDM), especially in critically ill, obese, and older adults, with a specific focus on ß-lactams and vancomycin. SUMMARY: The continued rise of antimicrobial resistance prompts the need to optimize antimicrobial dosing. The aim of TDM is to individualize antimicrobial dosing to achieve antibiotic exposures associated with improved patient outcomes. Initially, TDM was developed to minimize adverse effects during use of narrow therapeutic index agents. Today, patient and organism complexity are expanding the need for precision dosing through TDM services. Alterations of pharmacokinetics and pharmacodynamics (PK/PD) in the critically ill, obese, and older adult populations, in conjunction with declining organism susceptibility, complicate attainment of therapeutic targets. Over the last decade, antimicrobial TDM has expanded with the emergence of literature supporting ß-lactam TDM and a shift from monitoring vancomycin trough concentrations to monitoring of the ratio of area under the concentration (AUC) curve to minimum inhibitory concentration (MIC). PK/PD experts should be at the forefront of implementing precision dosing practices. CONCLUSION: Precision dosing through TDM is expanding and is especially important in populations with altered PK/PD, including critically ill, obese, and older adults. Due to wide PK/PD variability in these populations, TDM is vital to maximize antimicrobial effectiveness and decrease adverse event rates. However, there is still a need for studies connecting TDM to patient outcomes. Providing patient-specific care through ß-lactam TDM and transitioning to vancomycin AUC/MIC monitoring may be challenging, but with experts at the forefront of this initiative, PK-based optimization of antimicrobial therapy can be achieved.

Clinical and Microbiologic Outcomes in Patients with Monomicrobial Stenotrophomonas maltophilia Infections.

Stenotrophomonas maltophilia is an opportunistic pathogen observed in nosocomial infections. Due to biofilm production and resistance to numerous antimicrobials, eradication is difficult. This study evaluated outcomes for monomicrobial S. maltophilia infections. Seventy-six patients were included, with 45 patients on trimethoprim-sulfamethoxazole and 31 patients on levofloxacin. Overall clinical cure, microbiological eradication, and 28-day mortality were observed in 79%, 82%, and 14% of patients, respectively. The use of trimethoprim-sulfamethoxazole or levofloxacin resulted in high cure rates; however, a trend toward resistance selection with levofloxacin was identified.

Training a Drug to Do New Tricks: Insights on Stability of Meropenem Administered as a Continuous Infusion.

BACKGROUND: The antibiotic armamentarium used to combat multi-drug resistant organisms (MDROs) include carbapenems. Continuous infusion (CI) dosing is frequently employed to maximize beta-lactam efficacy; however, use of meropenem CI has been limited due to concerns with product instability. OBJECTIVE: The primary objective of this study was to quantify meropenem serum concentrations to reflect drug stability when administered as CI over 8- or 12-h exchanges. In addition, a stability experiment was performed to further establish meropenem integrity over 12 h. The secondary objectives were to assess the ability of meropenem to achieve target pharmacokinetic/pharmacodynamic (PK/PD) exposures relative to the minimum inhibitory concentration (MIC) of the pathogen, and to determine clinical cure. METHODS: This was a retrospective, observational study on use of CI meropenem (infused either over 8- or 12- h) at a 1% concentration. The stability experiment was conducted on 1% meropenem at room temperature. RESULTS: In 22 patients, a median meropenem daily dose of 6 g/day (range 2-6 g/day) resulted in a median serum concentration of 17.8 mg/L (interquartile range, 9.3-27.8 mg/L). In 95% of cases, meropenem delivered as CI resulted in free drug concentrations at or above the MIC of the pathogen for the entire dosing interval. Clinical cure was achieved in 80% of patients included in this review. The stability experiment revealed negligible drug degradation at the end of the 12-h dosing interval. CONCLUSIONS: The data from this study provides compelling evidence for the use of meropenem as CI utilizing either a 12- or 8-h exchange process.

Preventing the Post-Antibiotic Era by Training Future Pharmacists as Antimicrobial Stewards.

Antimicrobials enable modern medicine, but their efficacy is a limited resource. In the past 20 years, antimicrobial development has slowed dramatically while antimicrobial resistance continues to rise. In response to this, there has been an increased focus on strategically managing antimicrobial use with an approach called "antimicrobial stewardship." Antimicrobial stewardship programs have been endorsed by health systems, professional societies, regulators, and government. These programs have been shown to reduce antimicrobial use, slow the growth of antimicrobial resistance, and improve patient outcomes. This commentary will discuss recent mandates for antimicrobial stewardship, compare current approaches to teaching infectious diseases pharmacotherapy with the skills and knowledge required for antimicrobial stewardship, and provide recommendations for and examples of best practices in training student pharmacists to become antimicrobial stewards.

Assessing antimicrobial stewardship initiatives: Clinical evaluation of cefepime or piperacillin/tazobactam in patients with bloodstream infections secondary to AmpC-producing organisms.

Management of micro-organisms harbouring AmpC ß-lactamases remains challenging. Carbapenems are often considered first-line agents. Due to growing concern regarding carbapenem-resistant Enterobacteriaceae, integrating non-carbapenem treatment strategies is being explored for these pathogens. The primary objective of this study was to evaluate clinical outcomes in patients with bacteraemia secondary to AmpC-producing organisms treated with cefepime or piperacillin/tazobactam (TZP). A retrospective study of adult patients receiving cefepime or TZP for the treatment of AmpC -producing organisms with positive cefoxitin screen (i.e. Citrobacter, Enterobacter or Serratia spp. along with cefoxitin resistance) isolated from blood cultures was conducted. The primary endpoint was clinical cure at end of therapy (EOT). Secondary endpoints included microbiological eradication, frequency of susceptibility changes following treatment, and 7- and 30-day all-cause mortality. Clinical cure at EOT was 87.1%, with 93.2% of patients achieving microbiological eradication. The 7- and 30-day mortality rates were 3.8% and 10.6%, respectively. Organism susceptibility was exceptionally high, with minimum inhibitory concentrations (MICs) of ≤2 µg/mL in 90% of patients treated with cefepime (n = 108). Selection for resistance to third-generation cephalosporins or primary antimicrobial therapy was infrequent at 6.1% (8/132). In conclusion, use of cefepime or TZP for management of AmpC bloodstream infections was associated with clinical and microbiological cure with infrequent selection for resistance.

Survival in Patients with Candida glabrata Bloodstream Infection Is Associated with Fluconazole Dose.

Robust pharmacodynamic indices that align fluconazole dose or exposure with outcomes in invasive candidiasis due to Candida glabrata remain elusive. The purpose of this retrospective multicenter study was to evaluate a cohort of 127 patients with C. glabrata fungemia treated with fluconazole, using adjusted analyses to identify risk factors for 28-day death. No significant correlations were found between fluconazole area under the curve (AUC), AUC/MIC ratio, or MIC and survival. In multivariate logistic regression analyses, however, higher average fluconazole dose (odds ratio [OR], 1.006 [95% confidence interval [CI], 1.001 to 1.010]; P = 0.008), average fluconazole dose of ≥400 mg (OR, 3.965 [95% CI, 1.509 to 10.418]; P = 0.005), and higher fluconazole dose on day 1 of therapy (OR, 1.007 [95% CI, 1.002 to 1.011]; P = 0.002) were found to be independent predictors of 28-day survival. Additionally, the presence of a central venous catheter at the time of infection was found to be a significant risk factor for death. In conclusion, we found fluconazole dose to be an independent predictor of 28-day survival for patients with C. glabrata fungemia, with doses of ≥400 mg/day being associated with 28-day survival rates approaching 90%. These data indicate the use and efficacy of fluconazole in the treatment of this serious infection. Aggressive dosing appears to be necessary when fluconazole is used for the treatment of C. glabrata fungemia, irrespective of MIC.

Optimization of Voriconazole Therapy for the Treatment of Invasive Fungal Infections in Adults.

Therapeutic concentrations of voriconazole in invasive fungal infections (IFIs) are ensured using a drug monitoring approach, which relies on attainment of steady-state pharmacokinetics. For voriconazole, time to reach steady state can vary from 5-7 days, not optimal for critically ill patients. We developed a population pharmacokinetic/pharmacodynamic model-based approach to predict doses that can maximize the net benefit (probability of efficacy-probability of adverse events) and ensure therapeutic concentrations, early on during treatment. The label-recommended 200 mg voriconazole dose resulted in attainment of targeted concentrations in ≥80% patients in the case of Candida spp. infections, as compared to only 40-50% patients, with net benefit ranging from 5.8-61.8%, in the case of Aspergillus spp. infections. Voriconazole doses of 300-600 mg were found to maximize the net benefit up to 51-66.7%, depending on the clinical phenotype (due to CYP2C19 status and pantoprazole use) of the patient and type of Aspergillus infection.

Ampicillin for the treatment of complicated urinary tract infections caused by vancomycin-resistant Enterococcus spp (VRE): a single-center university hospital experience.

Vancomycin-resistant enterococci (VRE) are a common cause of urinary tract infections (UTIs) and are typically multidrug resistant, including ampicillin. This retrospective study evaluated outcomes of 84 adult patients hospitalized between January 2007 and December 2015 with ampicillin- and vancomycin-resistant enterococcus isolates causing UTI and treated with ampicillin. Treatment response was classified as clinical cure and microbiological eradication. Clinical cure was achieved in 88.1% (74/84) of patients. In patients with follow-up cultures, microbiological eradication was achieved in 86% (50/58) of patients. Cure rates were similar in patients with indwelling urinary catheters (n = 45) receiving catheter exchange/removal (90.47%; 19/21) versus catheter retention (87.5%; 21/24). Presence of co-morbidities, such as diabetes and chronic kidney disease, were not associated with increased risk of treatment failure. Immunocompromised patients achieved lower cure rates of 78.1% (25/32) compared with 94.2% (49/52) among those without immune impairment (P = 0.038). Presence of an underlying urinary tract abnormality was also associated with a lower cure rate of 71.4% (15/21) compared with 93.7% (59/63) in those without urinary tract abnormalities (P = 0.0135). Overall cure rates remained high in all groups providing good evidence to support ampicillin for the treatment of complicated UTI caused by ampicillin- and vancomycin-resistant enterococci.

Acute kidney injury risk associated with piperacillin/tazobactam compared with cefepime during vancomycin therapy in hospitalised patients: a cohort study stratified by baseline kidney function.

Recent studies have found an association between piperacillin/tazobactam when added to vancomycin and acute kidney injury (AKI) risk. However, studies were limited by the small sample size and residual confounding. The aim of this study was to compare the risk of AKI with vancomycin plus piperacillin/tazobactam (VPT) versus vancomycin plus cefepime (VC) and to examine whether pre-existing renal impairment mediates the risk. This was a retrospective cohort study using electronic health records for patients admitted to two hospitals in 2012-2013. The outcome, AKI, was defined as an increase in serum creatinine level of ≥0.3 mg/dL or ≥50% from baseline. Patients were stratified by level of renal impairment as estimated by baseline creatinine clearance. Inverse probability of treatment weighting was used to balance baseline covariates between groups. Cox proportional hazards regression was used to evaluate VPT risk of AKI compared with VC. A total of 935 (17.53%) AKI cases were identified among 5335 patients receiving VPT or VC. VPT was associated with a higher risk of AKI relative to VC, with an adjusted hazard ratio (aHR) of 1.25 [95% confidence interval (CI) 1.11-1.42] in the total population and 1.70 (95% CI 1.44-2.02) in patients with normal baseline renal function. However, no elevated risk was found in patients with prior renal impairment (aHR = 0.81, 95% CI 0.65-1.01). VPT was associated with a higher risk of AKI relative to VC. The association was true in patients with normal renal function but not in those with pre-existing renal impairment.

Impact of the CYP2C19 genotype on voriconazole exposure in adults with invasive fungal infections.

OBJECTIVES: Voriconazole, a first-line agent for the treatment of invasive fungal infections (IFIs), is metabolized by CYP2C19. A significant proportion of patients fail to achieve therapeutic trough concentrations with standard weight-based voriconazole dosing, placing them at increased risk for treatment failure, which can be life threatening. We sought to test the association between the CYP2C19 genotype and subtherapeutic voriconazole concentrations in adults with IFIs. PATIENT AND METHODS: Adults receiving weight-based voriconazole dosing for the treatment of IFIs were genotyped for the CYP2C19*2, *3, and *17 polymorphisms, and CYP2C19 metabolizer phenotypes were inferred. Steady-state voriconazole trough plasma concentrations and the prevalence of subtherapeutic troughs (<2 mg/l) were compared between patients with the CYP2C19*17/*17 (ultrarapid metabolizer, UM) or *1/*17 (rapid metabolizer, RM) genotype versus those with other genotypes. Logistic regression, adjusting for clinical factors, was performed to estimate the odds of subtherapeutic concentrations. RESULTS: Of 70 patients included (mean age 52.5±18 years), 39% were RMs or UMs. Compared with patients with the other phenotypes, RMs/UMs had a lower steady-state trough concentration (4.26±2.2 vs. 2.86±2.3, P=0.0093) and a higher prevalence of subtherapeutic troughs (16 vs. 52%, P=0.0028), with an odds ratio of 5.6 (95% confidence interval: 1.64-19.24, P=0.0044). CONCLUSION: Our findings indicate that adults with the CYP2C19 RM or UM phenotype are more likely to have subtherapeutic concentrations with weight-based voriconazole dosing. These results corroborate previous findings in children and support the potential clinical utility of CYP2C19 genotype-guided voriconazole dosing to avoid underexposure in RMs and UMs.

Multicenter Observational Study of Ceftaroline Fosamil for Methicillin-Resistant Staphylococcus aureus Bloodstream Infections.

Novel therapies for methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) are needed in the setting of reduced antibiotic susceptibilities and therapeutic failure. Ceftaroline is a cephalosporin antibiotic with MRSA activity. Although not FDA approved for MRSA BSI, ceftaroline has generated much interest as a potential treatment option. However, detailed descriptions of its use in this setting remain limited. To address this, we conducted a retrospective, multicenter, observational study of adult patients with MRSA BSI treated with at least 72 h of ceftaroline from 2011 to 2015. Safety outcomes were examined in the overall cohort, while efficacy outcomes were examined among patients who had not cleared their BSI prior to ceftaroline initiation. Data were also stratified by ceftaroline monotherapy or combination therapy. Predictors of clinical failure on ceftaroline treatment were also sought. Overall, 211 patients were included in the safety population; Clostridium difficile infection, rash, and neutropenia occurred in 6 patients (2.8%), 7 patients (3.3%), and 3 patients (1.4%), respectively. Clinical success was observed in 86 (68.3%) of the 126 patients included in the efficacy population. The monotherapy and combination therapy subgroups had similar proportions of patients experiencing success (69.7 and 64.9%, respectively). The median BSI durations post-ceftaroline treatment were 2 days (interquartile range, 1 to 4 days) for monotherapy and 3 days (interquartile range, 1.5 to 5 days) for combination therapy. Higher acute physiology and chronic health evaluation II scores and comorbid malignancy independently predicted treatment failure. Ceftaroline appears effective for MRSA BSI as both monotherapy and combination therapy. However, comparative studies are needed to further delineate the role of ceftaroline in MRSA BSI treatment.