Meropenem-Vaborbactam as Salvage Therapy for Ceftazidime-Avibactam-Resistant Klebsiella pneumoniae Bacteremia and Abscess in a Liver Transplant Recipient.

We report a case of a 24-year-old liver transplant recipient who developed hepatic artery thrombosis and graft failure, which was complicated by subphrenic abscess and persistent Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae bacteremia. Ceftazidime-avibactam treatment led to emergence of resistance, and alternative combination therapy failed due to persistent infection and toxicity. The infection resolved after initiation of meropenem-vaborbactam, which created a bridge to retransplantation. Treatment-emergent ceftazidime-avibactam resistance is increasingly recognized, suggesting a role for meropenem-vaborbactam.

Evaluation of Antimicrobial Stewardship-Related Alerts Using a Clinical Decision Support System.

Background: Information technology, including clinical decision support systems (CDSS), have an increasingly important and growing role in identifying opportunities for antimicrobial stewardship-related interventions. Objective: The aim of this study was to describe and compare types and outcomes of CDSS-built antimicrobial stewardship alerts. Methods: Fifteen alerts were evaluated in the initial antimicrobial stewardship program (ASP) review. Preimplementation, alerts were reviewed retrospectively. Postimplementation, alerts were reviewed in real-time. Data collection included total number of actionable alerts, recommendation acceptance rates, and time spent on each alert. Time to de-escalation to narrower spectrum agents was collected. Results: In total, 749 alerts were evaluated. Overall, 306 (41%) alerts were actionable (173 preimplementation, 133 postimplementation). Rates of actionable alerts were similar for custom-built and prebuilt alert types (39% [53 of 135] vs 41% [253 of 614], P = .68]. In the postimplementation group, an intervention was attempted in 97% of actionable alerts and 70% of interventions were accepted. The median time spent per alert was 7 minutes (interquartile range [IQR], 5-13 minutes; 15 [12-17] minutes for actionable alerts vs 6 [5-7] minutes for nonactionable alerts, P < .001). In cases where the antimicrobial was eventually de-escalated, the median time to de-escalation was 28.8 hours (95% confidence interval [CI], 10.0-69.1 hours) preimplementation vs 4.7 hours (95% CI, 2.4-22.1 hours) postimplementation, P < .001. Conclusions: CDSS have played an important role in ASPs to help identify opportunities to optimize antimicrobial use through prebuilt and custom-built alerts. As ASP roles continue to expand, focusing time on customizing institution specific alerts will be of vital importance to help redistribute time needed to manage other ASP tasks and opportunities.

Influence of Colistin Dose on Global Cure in Patients with Bacteremia Due to Carbapenem-Resistant Gram-Negative Bacilli.

The increasing prevalence of multidrug-resistant (MDR) nosocomial infections accounts for increased morbidity and mortality of such infections. Infections with MDR Gram-negative isolates are frequently treated with colistin. Based on recent pharmacokinetic studies, current colistin dosing regimens may result in a prolonged time to therapeutic concentrations, leading to suboptimal and delayed effective treatment. In addition, studies have demonstrated an association between an increased colistin dose and improved clinical outcomes. However, the specific dose at which these outcomes are observed is unknown and warrants further investigation. This retrospective study utilized classification and regression tree (CART) analysis to determine the dose of colistin most predictive of global cure at day 7 of therapy. Patients were assigned to high- and low-dose cohorts based on the CART-established breakpoint. The secondary outcomes included microbiologic outcomes, clinical cure, global cure, lengths of intensive care unit (ICU) and hospital stays, and 7- and 28-day mortalities. Additionally, safety outcomes focused on the incidence of nephrotoxicity associated with high-dose colistin therapy. The CART-established breakpoint for high-dose colistin was determined to be >4.4 mg/kg of body weight/day, based on ideal body weight. This study evaluated 127 patients; 45 (35%) received high-dose colistin, and 82 (65%) received low-dose colistin. High-dose colistin was associated with day 7 global cure (40% versus 19.5%; P = 0.013) in bivariate and multivariate analyses (odds ratio [OR] = 3.40; 95% confidence interval [CI], 1.37 to 8.45; P = 0.008). High-dose colistin therapy was also associated with day 7 clinical cure, microbiologic success, and mortality but not with the development of acute kidney injury. We concluded that high-dose colistin (>4.4 mg/kg/day) is independently associated with day 7 global cure.

Impact of combination antimicrobial therapy on mortality risk for critically ill patients with carbapenem-resistant bacteremia.

There are limited treatment options for carbapenem-resistant Gram-negative infections. Currently, there are suggestions in the literature that combination therapy should be used, which frequently includes antibiotics to which the causative pathogen demonstrates in vitro resistance. This case-control study evaluated risk factors associated with all-cause mortality rates for critically ill patients with carbapenem-resistant Gram-negative bacteremia. Adult patients who were admitted to an intensive care unit with sepsis and a blood culture positive for Gram-negative bacteria resistant to a carbapenem were included. Patients with polymicrobial, recurrent, or breakthrough infections were excluded. Included patients were classified as survivors (controls) or nonsurvivors (cases) at 30 days after the positive blood culture. Of 302 patients screened, 168 patients were included, of whom 90 patients died (53.6% [cases]) and 78 survived (46.4% [controls]) at 30 days. More survivors received appropriate antibiotics (antibiotics with in vitro activity) than did nonsurvivors (93.6% versus 53.3%; P < 0.01). Combination therapy, defined as multiple appropriate agents given for 48 h or more, was more common among survivors than nonsurvivors (32.1% versus 7.8%; P < 0.01); however, there was no difference in multiple-agent use when in vitro activity was not considered (including combinations with carbapenems) (87.2% versus 80%; P = 0.21). After adjustment for baseline factors with multivariable logistic regression, combination therapy was independently associated with decreased risk of death (odds ratio, 0.19 [95% confidence interval, 0.06 to 0.56]; P < 0.01). These data suggest that combination therapy with multiple agents with in vitro activity is associated with improved survival rates for critically ill patients with carbapenem-resistant Gram-negative bacteremia. However, that association is lost if in vitro activity is not considered.

Association between colistin dose and microbiologic outcomes in patients with multidrug-resistant gram-negative bacteremia.

BACKGROUND: Colistin is increasingly used for the treatment of multidrug-resistant gram-negative infections. However, colistin dosing varies greatly and the optimal regimen is unknown. The purpose of this study was to determine if colistin dosing correlates with patient outcomes. METHODS: This retrospective study included patients with gram-negative bacteremia treated with intravenous colistin for at least 72 hours. The primary objective was to determine if colistin dose (mg of colistin base activity/kg/day) independently predicts day-7 microbiological success. Secondary objectives included evaluation for an association between colistin dose and 7-day mortality, 28-day mortality, and the development of acute kidney insufficiency (AKI). RESULTS: Seventy-six patients were included in the analysis, with 52 patients (68%) achieving 7-day microbiological success. The median colistin dose was significantly higher in patients who achieved microbiological success (2.9 vs 1.5 mg/kg/day; P = .011). After adjusting for baseline severity of illness and concomitant tigecyline use, higher colistin dose independently correlated with microbiological success (adjusted odds ratio per 1 mg/kg/day = 1.74; 95% confidence interval, 1.11-2.71; P = .015). The median colistin dose was also significantly higher among survivors at day 7 (2.7 vs 1.5 mg/kg/day; P = .007). However, no difference was observed in colistin dose when comparing survivors and nonsurvivors at day 28. A significantly higher colistin dose was given to patients who developed AKI during therapy (3.8 vs 1.6 mg/kg/day; P < .001). CONCLUSIONS: Higher colistin dose independently predicted microbiological success, which may partially explain the similar association with 7-day mortality. However, higher colistin doses may also precipitate worsening renal function.

Spectrum scores: Toward a better definition of de-escalation.

Spectrum scores measure antimicrobial utilization while also quantifying the spectrum of activity. Accordingly, changes in spectrum score can be used to identify antimicrobial de-escalation. We show that spectrum-score-based de-escalation has a 95.7% positive percentage agreement and 81.6% negative percentage agreement versus de-escalation defined as stopping either antistaphylococcal or antipseudomonal agents.

Mixed methods evaluation of handshake antimicrobial stewardship on adult inpatient medicine floors.

Objective: To evaluate the effects of handshake antimicrobial stewardship on medicine floors at a large tertiary care hospital. Design: Retrospective observational study. Setting: 1,278-bed academic hospital. Patients: Adults admitted to non-ICU medicine services. Interventions: A handshake stewardship team consisting of an infectious diseases (ID) physician and pharmacist reviewed charts of patients receiving antimicrobials on medicine floors without a formal ID consult. Recommendations were communicated in-person to providers and acceptance rates were examined with descriptive statistics. Additional data regarding program perception among providers were obtained via surveys. Antibiotic usage trends were extracted from National Healthcare Safety Network Antimicrobial Use option data and evaluated using an interrupted time-series analysis pre- and post-intervention. Results: The overall acceptance rate of interventions was 80%, the majority being recommendations either to discontinue (37%) or de-escalate therapy (28%). Medical residents and hospitalists rated the intervention favorably with 90% reporting recommendations were helpful all or most of the time. There was a statistically significant decrease in vancomycin (78 vs 70 DOT/1,000 d present (DP), p = 0.002) and meropenem (24 vs 17 DOT/1,000 DP, p = 0.007) usage and a statistically significant increase in amoxicillin-clavulanate usage (11 vs 15 DOT/1,000 DP, p < 0.001). Overall antibiotic usage remained unchanged by the intervention, though pre-intervention there was a nonsignificant overall increasing trend while post-intervention there was a nonsignificant decreasing trend in overall usage. There was no change in in-hospital mortality. Conclusion: The addition of handshake stewardship with adult medicine services was favorably viewed by participants and led to shifts in antibiotic usage.

Experience with fosfomycin for treatment of urinary tract infections due to multidrug-resistant organisms.

Fosfomycin has shown promising in vitro activity against multidrug-resistant (MDR) urinary pathogens; however, clinical data are lacking. We conducted a retrospective chart review to describe the microbiological and clinical outcomes of urinary tract infections (UTIs) with MDR pathogens treated with fosfomycin tromethamine. Charts for 41 hospitalized patients with a urine culture for an MDR pathogen who received fosfomycin tromethamine from 2006 to 2010 were reviewed. Forty-one patients had 44 urinary pathogens, including 13 carbapenem-resistant Klebsiella pneumoniae (CR-Kp), 8 Pseudomonas aeruginosa, and 7 vancomycin-resistant Enterococcus faecium (VRE) isolates, 7 extended-spectrum beta-lactamase (ESBL) producers, and 9 others. In vitro fosfomycin susceptibility was 86% (median MIC, 16 µg/ml; range, 0.25 to 1,024 µg/ml). Patients received an average of 2.9 fosfomycin doses per treatment course. The overall microbiological cure was 59%; failure was due to either relapse (24%) or reinfection UTI (17%). Microbiological cure rates by pathogen were 46% for CR-Kp, 38% for P. aeruginosa, 71% for VRE, 57% for ESBL producers, and 100% for others. Microbiological cure (n = 24) was compared to microbiological failure (n = 17). There were significantly more solid organ transplant recipients in the microbiological failure group (59% versus 21%; P = 0.02). None of the patients in the microbiological cure group had a ureteral stent, compared to 24% of patients within the microbiological failure group (P = 0.02). Fosfomycin demonstrated in vitro activity against UTIs due to MDR pathogens. For CR-KP, there was a divergence between in vitro susceptibility (92%) and microbiological cure (46%). Multiple confounding factors may have contributed to microbiological failures, and further data regarding the use of fosfomycin for UTIs due to MDR pathogens are needed.

The Implementation and Effect of Weekend Pharmacy-Driven Antimicrobial Stewardship Services at a Large Academic Medical Center.

BACKGROUND: In September 2018, pharmacy antimicrobial stewardship (AMS) services were expanded to include weekends at this academic medical center. Activities performed by AMS pharmacists on the weekends include blood culture rapid diagnostic (RDT) review, antiretroviral therapy (ART) review, prospective audit and feedback (PAF) utilizing clinical decision support, vancomycin dosing, and operational support. The purpose of this study was to assess the operational and clinical impact of these expanded AMS services. METHODS: This single-center, quasi-experimental study included data from weekends before (9/2017-11/2017) and after (9/2018-11/2018) implementation. The descriptive primary outcome was the number of activities completed for each AMS activity type in the post-implementation group only. Secondary outcomes were time to AMS opportunity resolution, time to escalation or de-escalation following PAF or RDT alert, time to resolution of miscellaneous AMS related opportunities, length of stay (LOS), and antimicrobial use outcomes. RESULTS: During the post-implementation period 1258 activities were completed, averaging 97/weekend. Inclusion criteria for time to resolution outcomes were met by 72 patients pre-implementation and 59 patients post. The median (IQR) time to AMS opportunity resolution decreased from 18.5 hours pre-intervention (7.7-35.7) to 8.5 hours post-intervention (IQR 1.8-14.0), p < 0.01. Time to escalation was 11.6 hours compared to 1.7 hours (p = 0.1), de-escalation 16.7 hours compared to 10.8 hours (p = 0.03), and miscellaneous opportunity 40.8 hours compared to 13.2 hours (p = 0.01). No differences were observed in LOS or antimicrobial use outcomes. CONCLUSION: Presence of pharmacist-driven weekend AMS services significantly reduced time to resolution of AMS opportunities. These data support the value of weekend AMS services.

Evaluation of a hybrid antimicrobial restriction process at a large academic medical center.

We conducted a retrospective review of a hybrid antimicrobial restriction process demonstrating adherence to appropriate use criteria in 72% of provisional-only orders, in 100% of provisional orders followed by ID orders, and in 97% of ID-initiated orders. Therapy interruptions occurred in 24% of provisional orders followed by ID orders.

Assessment of Antibiotic De-escalation by Spectrum Score in Patients With Nosocomial Pneumonia: A Single-Center, Retrospective Cohort Study.

BACKGROUND: Hospital-acquired and ventilator-associated pneumonia (HAP/VAP) cause significant mortality. Guidelines recommend empiric broad-spectrum antibiotics followed by de-escalation (DE). This study sought to assess the impact of DE on treatment failure. METHODS: This single-center retrospective cohort study screened all adult patients with a discharge diagnosis code for pneumonia from 2016 to 2019. Patients were enrolled if they met predefined criteria for HAP/VAP ≥48 hours after admission. Date of pneumonia diagnosis was defined as day 0. Spectrum scores were calculated, and DE was defined as a score reduction on day 3 versus day 1. Patients with DE were compared to patients with no de-escalation (NDE). The primary outcome was composite treatment failure, defined as all-cause mortality or readmission for pneumonia within 30 days of diagnosis. RESULTS: Of 11860 admissions screened, 1812 unique patient-admissions were included (1102 HAP, 710 VAP). Fewer patients received DE (876 DE vs 1026 NDE). Groups were well matched at baseline, although more patients receiving DE had respiratory cultures ordered (56.6% vs 50.6%, P = .011). There was no difference in composite treatment failure (35.0% DE vs 33.8% NDE, P = .604). De-escalation was not associated with treatment failure on multivariable Cox regression analysis (hazard ratio, 1.13; 95% confidence interval, 0.96-1.33). Patients receiving DE had fewer antibiotic days (median 9 vs 11, P < .0001), episodes of Clostridioides difficile infection (2.2% vs 3.8%, P = .046), and hospital days (median 20 vs 22 days, P = .006). CONCLUSIONS: De-escalation and NDE resulted in similar rates of 30-day treatment failure; however, DE was associated with fewer antibiotic days, episodes of C difficile infection, and days of hospitalization.

Antimicrobial Stewardship Practice in the Ambulatory Setting From a National Cohort.

BACKGROUND: The majority of antimicrobial use occurs in the ambulatory setting. Antimicrobial stewardship programs (ASPs) are effective in improving appropriate prescribing and are now required by accreditation bodies. METHODS: This was a cross-sectional, multicenter survey describing the current state of ambulatory ASPs in a national cohort of Vizient member hospitals with ambulatory healthcare settings and serves as a benchmark for stewardship strategies related to program effectiveness. RESULTS: One hundred twenty-nine survey responses from a variety of institution types across 44 states were received. Survey respondents reported a fully functioning ASP in 7% (9 of 129) of ambulatory practices compared with 88% (114 of 129) of inpatient institutions. Effectiveness in at least 1 antibiotic use-related outcome (ie, utilization, resistance, Clostridioides difficile infection, or cost) in the past 2 years was reported in 18% (18 of 100) of ambulatory and 84% (103 of 123) of inpatient ASPs. Characteristics of ambulatory ASPs demonstrating effectiveness were institution guidelines (89%, 16 of 18), rapid diagnostic testing for respiratory viruses or group A Streptococcus (89% 16 of 18), outpatient antibiograms (78% 14 of 18), and dedicated pharmacist support (72%, 13 of 18). Ambulatory ASP effectiveness was shown to increase as programs met more of the Centers for Disease Control and Prevention (CDC) Core Elements of Outpatient Antimicrobial Stewardship (P < .001). CONCLUSIONS: Antimicrobial stewardship programs are needed in the ambulatory setting, but they are not common. Currently, few ambulatory ASPs in this survey self-identify as fully functioning. The CDC Core Elements of antimicrobial stewardship should remain foundational for ASP development and expansion.

New antibiotics for healthcare-associated pneumonia.

Current antibiotics available for the treatment of healthcare-associated pneumonia (HCAP) may result in clinical failure due to resistance development, side effect intolerance, or poor pharmacokinetic-pharmacodynamic profiles. New agents active against common HCAP pathogens are needed. The mechanism of action, spectrum of activity, pharmacokinetics, adverse effects, and clinical efficacy of seven new agents in clinical development or recently approved with either methicillin-resistant Staphylococcus aureus (MRSA) or pseudomonal activity are reviewed. They include doripenem, a new antipseudomonal carbapenem; ceftobiprole and ceftaroline, two anti-MRSA cephalosporins; iclaprim, a selective dihydrofolate reductase antagonist; and three glycopeptides, dalbavancin, telavancin, and oritavancin.

A Retrospective Multisite Case-Control Series of Concomitant Use of Daptomycin and Statins and the Effect on Creatine Phosphokinase.

OBJECTIVE: Daptomycin has been associated with increased creatine phosphokinase (CPK) due to muscle injury leading to myalgias and muscle weakness. Statins have been proven to cause the same effects and it is recommended to discontinue the use of statins while on daptomycin. Evidence regarding this drug interaction is mixed. This study evaluated the risk of CPK elevation in concomitant use of daptomycin and statins compared to daptomycin alone. METHOD: This is a multisite retrospective case-control study of patients who received daptomycin therapy with monitoring of CPK. Rates of CPK elevations were compared in patients receiving daptomycin with a statin versus daptomycin alone. To estimate the association between CPK elevation and daptomycin therapy controlling for other risk factors, logistic regression was used to analyze data. Statistical significance was determined at ɑ of 0.05. RESULTS: A total of 3658 patients were included in the study, with 2787 on daptomycin therapy alone and 871 with concurrent statin use. The incidence of CPK elevation was 90 events (3.2%) in the daptomycin group and 26 events (3.0%) in the concurrent statin group. Patients who received daptomycin therapy in addition to statins had no statistically significant difference from patients on daptomycin alone (hazard ratio, 1.05; P = .85; 95% confidence interval, 0.61-1.84). After adjusting for potential risk factors, the hazards ratio remained almost the same. CONCLUSIONS: Concomitant use of daptomycin and statin did not show an increase risk of CPK elevation. Clinicians may consider concomitant use of daptomycin and statin therapy with weekly CPK monitoring.

Evaluation of an electronic antimicrobial time-out on antimicrobial utilization at a large health system.

We evaluated the impact of an electronic health record based 72-hour antimicrobial time-out (ATO) on antimicrobial utilization. We observed that 6 hours after the ATO, 21% of empiric antimicrobials were discontinued or de-escalated. There was a significant reduction in the duration of antimicrobial therapy but no impact on overall antimicrobial usage metrics.

Implementation of a Stewardship Initiative on Respiratory Viral PCR-based Antibiotic Deescalation.

OBJECTIVE: Respiratory viral polymerase chain reaction (RV PCR) tests assist in rapidly identifying viral pathogens and differentiating viral versus bacterial causes of pneumonia. Studies evaluating the use of RV PCR tests on antibiotic use in adults have demonstrated mixed results. We implemented an antimicrobial stewardship (ASP) intervention for patients with a positive RV PCR test result who were receiving broad-spectrum antibiotics and aimed to assess the impact on antibiotic usage. METHODS: Retrospective quasi-experimental study of adult hospitalized patients comparing time to antibiotic deescalation, duration of antibiotic therapy, and antiviral use preintervention (January-March 2016) and postintervention (January-March 2017). RESULTS: Of 172 ASP alerts reviewed, 55 (32%) were considered actionable. Of these, 47% of interventions were accepted. No significant difference was observed in median time to antibiotic deescalation (pre: 2.7 days vs post: 2.3 days, p=0.88). Time to discontinuation of antimicrobial therapy pre- and postintervention was reduced from 4 to 1.9 days (p=0.057) for piperacillin-tazobactam, from 2.7 to 1.8 days (p=0.75) for ceftriaxone, and from 3.6 to 2 days (p=0.4) for levofloxacin, respectively. Time to initiation of oseltamivir for influenza was significantly shorter in the postintervention group (pre: 11.3 hrs vs post: 3.6 hrs, p=0.02). CONCLUSION: A third of patients receiving broad-spectrum antibiotics with a positive RV PCR had an opportunity for antimicrobial optimization, although this did not translate into a significant impact on the time to antibiotic deescalation or overall antibiotic use. Combination of RV PCR results with biomarkers to rule out bacterial coinfections and chest radiographic findings may help enhance the likelihood of accepted antibiotic deescalation recommendations and represents an area of future research.

Cost-effectiveness of three different strategies for the treatment of first recurrent Clostridium difficile infection diagnosed in a community setting.

OBJECTIVE: A significant portion of patients with Clostridium difficile infections (CDI) experience recurrence, and there is little consensus on its treatment. With the availability of newer agents for CDI and the added burdens of recurrent disease, a cost-effectiveness analysis may provide insight on the most efficient use of resources. DESIGN: A decision-tree analysis was created to compare the cost-effectiveness of 3 possible treatments for patients with first CDI recurrence: oral vancomycin, fidaxomicin, or bezlotoxumab plus vancomycin. The model was performed from a payer's perspective with direct cost inputs and a timeline of 1 year. A systematic review of literature was performed to identify clinical, utility, and cost data. Quality-adjusted life years (QALY) and incremental cost-effectiveness ratios were calculated. The willingness-to-pay (WTP) threshold was set at $100,000 per QALY gained. The robustness of the model was tested using one-way sensitivity analyses and probabilistic sensitivity analysis. RESULTS: Vancomycin had the lowest cost ($15,692) and was associated with a QALY gain of 0.8019 years. Bezlotoxumab plus vancomycin was a dominated strategy. Fidaxomicin led to a higher QALY compared to vancomycin, at an incremental cost of $500,975 per QALY gained. Based on our WTP threshold, vancomycin alone was the most cost-effective regimen for treating the first recurrence of CDI. Sensitivity analyses demonstrated the model's robustness. CONCLUSIONS: Vancomycin alone appears to be the most cost-effective regimen for the treatment of first recurrence of CDI. Fidaxomicin alone led to the highest QALY gained, but at a cost beyond what is considered cost-effective.

Evaluation of Prophylactic Antibiotic Use for Delayed Sternal Closure After Cardiothoracic Operation.

BACKGROUND: Clinical practice guidelines provide recommendations for surgical prophylaxis in patients undergoing cardiothoracic procedures. However, currently no recommendations guide the management of antibiotic prophylaxis in patients who require delayed sternal closure after cardiothoracic operation. METHODS: This is a single-center, retrospective analysis. Data were extracted from The Society of Thoracic Surgery database and electronic medical record from July 2011 through January 2016. Patients included are adults (≥18 years old) after cardiothoracic operation with delayed sternal closure. RESULTS: A total of 167 patients were included for analysis. The majority of patients (131, 78.4%) were continued on routine antibiotics and 36 patients (21.6%) were switched to broad-spectrum antibiotics for prophylaxis. Of patients on routine antibiotic prophylaxis, 6 (4.6%) experienced a sternal surgical site infection, whereas 3 patients (8.3%) switched to broad-spectrum agents before chest closure experienced a sternal surgical site infection (p = 0.407). Eleven patients (6.6%) received an abbreviated duration of antibiotics, 52 patients (31.1%) were continued on antibiotics until the time of sternal closure, and 104 patients (62.3%) were continued on antibiotics past the time of sternal closure. The incidence of infection based on duration of prophylactic antibiotic was 0, 1 (1.9%), and 8 (7.7%), respectively (p = 0.352). CONCLUSIONS: Substantial variation was found in the duration and selection of antibiotic prophylaxis for patients with delayed sternal closure after cardiothoracic operation. Broad-spectrum antimicrobial agents and extended durations of antibiotic prophylaxis were not associated with benefits in the incidence of sternal wound infection and may increase the risk of adverse effects.