The prevalence of gram-negative bacteria with difficult-to-treat resistance and utilization of novel β-lactam antibiotics in the southeastern United States

Objective

To evaluate temporal trends in the prevalence of gram-negative bacteria (GNB) with difficult-to-treat resistance (DTR) in the southeastern United States. Secondary objective was to examine the use of novel β-lactams for GNB with DTR by both antimicrobial use (AU) and a novel metric of adjusted AU by microbiological burden (am-AU).

Design

Retrospective, multicenter, cohort.

Setting

Ten hospitals in the southeastern United States.

Methods

GNB with DTR including Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter spp. from 2015 to 2020 were tracked at each institution. Cumulative AU of novel β-lactams including ceftolozane/tazobactam, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/cilastatin/relebactam, and cefiderocol in days of therapy (DOT) per 1,000 patient-days was calculated. Linear regression was utilized to examine temporal trends in the prevalence of GNB with DTR and cumulative AU of novel β-lactams.

Results

The overall prevalence of GNB with DTR was 0.85% (1,223/143,638) with numerical increase from 0.77% to 1.00% between 2015 and 2020 (P = .06). There was a statistically significant increase in DTR Enterobacterales (0.11% to 0.28%, P = .023) and DTR Acinetobacter spp. (4.2% to 18.8%, P = .002). Cumulative AU of novel β-lactams was 1.91 ± 1.95 DOT per 1,000 patient-days. When comparing cumulative mean AU and am-AU, there was an increase from 1.91 to 2.36 DOT/1,000 patient-days, with more than half of the hospitals shifting in ranking after adjustment for microbiological burden.

Conclusions

The overall prevalence of GNB with DTR and the use of novel β-lactams remain low. However, the uptrend in the use of novel β-lactams after adjusting for microbiological burden suggests a higher utilization relative to the prevalence of GNB with DTR.

Incidence and predictors of complications in Gram-negative bloodstream infection

BACKGROUND

The incidence of metastatic complications in Gram-negative bloodstream infection (GN-BSI) remains undefined. This retrospective cohort study examines the incidence and predictors of complications within 90 days of GN-BSI.

METHODS

Patients with GN-BSIs hospitalized at two Prisma Health-Midlands hospitals in Columbia, South Carolina, USA from 1 January 2012 through 30 June 2015 were included. Complications of GN-BSI included endocarditis, septic arthritis, osteomyelitis, spinal infections, deep-seated abscesses, and recurrent GN-BSI. Kaplan-Meier analysis and multivariate Cox proportional hazards regression were used to examine incidence and risk factors of complications, respectively.

RESULTS

Among 752 patients with GN-BSI, median age was 66 years and 380 (50.5%) were women. The urinary tract was the most common source of GN-BSI (378; 50.3%) and Escherichia coli was the most common bacteria (375; 49.9%). Overall, 13.9% of patients developed complications within 90 days of GN-BSI. The median time to identification of these complications was 5.2 days from initial GN-BSI. Independent risk factors for complications were presence of indwelling prosthetic material (hazards ratio [HR] 1.73, 95% confidence intervals [CI] 1.08-2.78), injection drug use (HR 6.84, 95% CI 1.63-28.74), non-urinary source (HR 1.98, 95% CI 1.18-3.23), BSI due to S. marcescens, P. mirabilis or P. aeruginosa (HR 1.78, 95% CI 1.05-3.03), early clinical failure criteria (HR 1.19 per point, 95% CI 1.03-1.36), and persistent GN-BSI (HR 2.97, 95% CI 1.26-6.99).

CONCLUSIONS

Complications of GN-BSI are relatively common and may be predicted based on initial clinical response to antimicrobial therapy, follow-up blood culture results, and other host and microbiological factors.

Ecologic analysis of antimicrobial use in South Carolina hospitals during 2020-2022

Background

Factors influencing excessive antimicrobial utilization in hospitalized patients remain poorly understood, particularly with the COVID-19 pandemic.

Methods

In this retrospective cohort, we compared administrative data regarding antimicrobial prescriptions in hospitalized patients in South Carolina from March 2020 through September 2022. The study examined variables associated with antimicrobial use across demographics, COVID status, and length of stay, among other variables.

Results

Significant relationships were seen with antimicrobial use in COVID-19 positive patients (OR 2.00, 95% Confidence Interval (CI): 1.9-2.1), young adults (OR 1.08, 95% CI: 0.99-1.12, COVID-19 positive Blacks and Hispanics (OR 1.06, 95% CI: 1.01-1.11, OR 1.05, 95% CI: 0.89-1.23), and COVID-19 positive patients with ≥2 comorbid conditions (OR 1.55, 95% CI: 1.43-1.68).

Discussion

Further analysis in more than one healthcare system should explore these ecologic relationships further to understand if these are common trends to inform ongoing stewardship interventions.

Application of Precision Medicine Concepts in Ambulatory Antibiotic Management of Acute Pyelonephritis

Acute pyelonephritis (APN) is a relatively common community-acquired infection, particularly in women. The early appropriate antibiotic treatment of this potentially life-threatening infection is associated with improved outcomes. The international management guidelines for complicated urinary tract infections and APN recommend using oral antibiotics with <10% resistance among urinary pathogens. However, increasing antibiotic resistance rates among Escherichia coli and other Enterobacterales to fluoroquinolones, trimethoprim-sulfamethoxazole (TMP-SMX), and beta-lactams has left patients without reliable oral antibiotic treatment options for APN. This narrative review proposes using precision medicine concepts to improve empirical antibiotic therapy for APN in ambulatory settings. Whereas resistance rates to a particular antibiotic class may exceed 10% at the population-based level, the predicted antibiotic resistance rates based on patient-specific risk factors fall under 10% in many patients with APN on the individual level. The utilization of clinical tools for the prediction of fluoroquinolones, TMP-SMX, and third-generation cephalosporin resistance improves the ambulatory antibiotic management of APN. It may also reduce the need to switch antibiotic therapy later based on the in vitro antibiotic susceptibility testing results of bacterial isolates in urinary cultures. This approach may mitigate the burden of increasing antibiotic resistance in the community by ensuring that the initial antibiotic prescribed has the highest likelihood of treating APN appropriately.

Ten golden rules for optimal antibiotic use in hospital settings: the WARNING call to action

Antibiotics are recognized widely for their benefits when used appropriately. However, they are often used inappropriately despite the importance of responsible use within good clinical practice. Effective antibiotic treatment is an essential component of universal healthcare, and it is a global responsibility to ensure appropriate use. Currently, pharmaceutical companies have little incentive to develop new antibiotics due to scientific, regulatory, and financial barriers, further emphasizing the importance of appropriate antibiotic use. To address this issue, the Global Alliance for Infections in Surgery established an international multidisciplinary task force of 295 experts from 115 countries with different backgrounds. The task force developed a position statement called WARNING (Worldwide Antimicrobial Resistance National/International Network Group) aimed at raising awareness of antimicrobial resistance and improving antibiotic prescribing practices worldwide. The statement outlined is 10 axioms, or "golden rules," for the appropriate use of antibiotics that all healthcare workers should consistently adhere in clinical practice.

Intravenous versus Partial Oral Antibiotic Therapy in the Treatment of Uncomplicated Bloodstream Infection Due to Streptococcus Species

This retrospective cohort study examines effectiveness of partial oral antibiotic regimens in uncomplicated bloodstream infections (BSIs) due to Streptococcus species compared to standard intravenous therapy. Adult patients with uncomplicated streptococcal BSIs from April 2016 to June 2020 in seven hospitals in South Carolina, USA, were evaluated. Multivariate Cox proportional hazards regression was used to examine the time to treatment failure within 90 days of a BSI after adjustment for the propensity to receive partial oral therapy. Multivariate linear regression was used to examine the hospital length of stay (HLOS). Among the 222 patients included, 99 received standard intravenous antibiotics and 123 received partial oral therapy. Of the standard intravenous therapy group, 46/99 (46.5%) required outpatient parenteral antibiotic therapy (OPAT). There was no difference in the risk of treatment failure between partial oral and standard intravenous therapy (hazards ratio 0.53, 95% CI 0.18, 1.60; p = 0.25). Partial oral therapy was independently associated with a shorter HLOS after adjustments for the propensity to receive partial oral therapy and other potential confounders (-2.23 days, 95% CI -3.53, -0.94; p < 0.001). Transitioning patients to oral antibiotics may be a reasonable strategy in the management of uncomplicated streptococcal BSIs. Partial oral therapy does not seem to have a higher risk of treatment failure and may spare patients from prolonged hospitalizations and OPAT complications.

Optimization of Empirical Antimicrobial Therapy in Enterobacterales Bloodstream Infection Using the Extended-Spectrum Beta-Lactamase Prediction Score

Clinical tools for the prediction of antimicrobial resistance have been derived and validated without examination of their implementation in clinical practice. This study examined the impact of utilization of the extended-spectrum beta-lactamase (ESBL) prediction score on the time to initiation of appropriate antimicrobial therapy for bloodstream infection (BSI). The quasi-experimental cohort study included hospitalized adults with BSI due to ceftriaxone-resistant (CRO-R) Enterobacterales at three community hospitals in Columbia, South Carolina, USA before (January 2010 to December 2013) and after (January 2014 to December 2019) implementation of an antimicrobial stewardship intervention. In total, 45 and 101 patients with BSI due to CRO-R Enterobacterales were included before and after the intervention, respectively. Overall, the median age was 66 years, 85 (58%) were men, and 86 (59%) had a urinary source of infection. The mean time to appropriate antimicrobial therapy was 78 h before and 46 h after implementation of the antimicrobial stewardship intervention (p = 0.04). Application of the ESBL prediction score as part of an antimicrobial stewardship intervention was associated with a significant reduction in time to appropriate antimicrobial therapy in patients with BSI due to CRO-R Enterobacterales. Utilization of advanced rapid diagnostics may be necessary for a further reduction in time to appropriate antimicrobial therapy in this population.

1843. Intravenous versus Partial Oral Antibiotic Therapy in the Treatment of Uncomplicated Bloodstream Infection due to Streptococcus species

Background

Effectiveness of oral antibiotics for transition of therapy in uncomplicated bloodstream infections (BSI) due to Streptococcus species remains unclear. This retrospective cohort study examines effectiveness of partial oral antibiotic regimens in patients with uncomplicated BSI due to Streptococcus species compared to standard intravenous (IV) only therapy.

Methods

Adult patients with uncomplicated BSI due to Streptococcus species from April 2016 through June 2020 in 7 hospitals within Prisma Health in South Carolina were evaluated. Patients who died within 7 days of BSI were excluded to reduce the impact of survival bias. Multivariate Cox proportional hazards regression was used to examine time to treatment failure, defined as a composite of all-cause mortality and BSI recurrence within 90 days.

Results

A total of 222 patients with Streptococcus species BSI were included in the analysis. Overall, the median age was 62 years, and 116 (52.3%) were men. Beta-hemolytic streptococci (87; 39.2%) were the most common bloodstream isolates, followed by S. pneumoniae (76; 34.2%) and viridans group streptococci (59; 26.6%). Among this cohort, 99 patients received only IV antibiotics, and the remaining 123 received partial oral therapy. The median duration of therapy in both groups was 14 days, and median duration of IV antibiotics prior to oral transition was 4 days. Most patients in the partial oral group were transitioned to either oral beta-lactams (62; 50.4%) or fluoroquinolones (47; 38.2%). Of the IV only group, 46 (46.5%) required outpatient IV antibiotics. Treatment failure rates were 12.0% and 4.4% in the IV only and partial oral therapy groups, respectively (p=0.04). After adjustments for age, chronic comorbidities, and initial response to therapy within the first 72-96 hours, there was no difference in the risk of treatment failure in the partial oral compared to IV only group (hazards ratio 0.55, 95% CI 0.19-1.64; p=0.28).

Conclusion

Transitioning patients from IV to oral antibiotics may be a reasonable strategy in the management of uncomplicated BSI due to Streptococcus species. Partial oral therapy does not seem to have a higher treatment failure rate than standard IV only therapy and may spare many patients from outpatient IV antibiotics.

Disclosures

All Authors: No reported disclosures.

409. Temporal Trends in Antibiotic Use of New β-lactams for Gram-Negative Bacteria with Difficult-to-Treat Resistance in the Southeastern United States

Background

Several new β-lactam antibiotics were recently developed for treatment of serious infections due to gram-negative bacteria (GNB) with difficult-to-treat resistance (DTR). This multicenter retrospective cohort study examined temporal trends in prevalence of GNB with DTR and the use of new β-lactams in the southeastern United States.

Methods

The prevalence of GNB with DTR, including Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter species was determined in 9 hospitals geographically spread within the Southeastern Research Group Endeavor (SERGE-45) between 2015 to 2020. Antibiotic use (AU) of new β-lactams was also obtained from the 9 hospitals during the study period. New β-lactams included ceftolozane/tazobactam, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/cilastatin/relebactam, and cefiderocol. Logistic regression analysis was utilized to examine temporal trends in prevalence of GNB with DTR and cumulative AU of new β-lactams.

Results

The overall prevalence of GNB with DTR in the 9 hospitals was 0.78% with a numerical increase from 0.67% to 0.97% between 2015 and 2020 (p=0.067) [Figure]. DTR was more prevalent among Acinetobacter spp., followed by P. aeruginosa, and Enterobacterales (11.8%, 3.5%, and 0.2%, respectively). There was a significant increase in the prevalence of DTR isolates among Acinetobacter spp. from 2.7% to 20.7% (p&lt; 0.001) and Enterobacterales from 0.07% to 2.6% (p=0.025), but not P. aeruginosa (p=0.46) between 2015 and 2020. The cumulative AU of new β-lactams in the 9 hospitals was 2 days of therapy per 1000 patient-days. There was numerical increase in AU of these agents from 0.03 to 2.22 days of therapy per 1000 patient days during the 6-year study period (p=0.096) [Figure].

Conclusion

The overall prevalence of GNB with DTR and cumulative use of new β-lactams remain relatively low in the southeastern United States. However, the upward trend in prevalence of DTR isolates, particularly among Acinetobacter spp. and Enterobacterales, is concerning and may drive future increased use of β-lactams. Additional efforts to benchmark the use and appropriateness of new β-lactams are crucial to preserve their efficacy against bacteria with DTR.

Disclosures

P. Brandon Bookstaver, PharmD, Spero Therapeutics: Advisor/Consultant Julie Ann Justo, PharmD, MS, FIDSA, BCPS-AQ ID, bioMerieux: Honoraria|bioMerieux: Honoraria|Entasis Therapeutics: Advisor/Consultant|Entasis Therapeutics: Advisor/Consultant|Gilead Sciences: Advisor/Consultant|Gilead Sciences: Advisor/Consultant|Merck & Co: Advisor/Consultant|Merck & Co: Advisor/Consultant|Shionogi: Advisor/Consultant|Shionogi Inc.: Advisor/Consultant|Spero Therapeutics: Honoraria|Spero Therapeutics: Honoraria|Vaxart: Stocks/Bonds Julie Ann Justo, PharmD, MS, FIDSA, BCPS-AQ ID, bioMerieux: Honoraria|bioMerieux: Honoraria|Entasis Therapeutics: Advisor/Consultant|Entasis Therapeutics: Advisor/Consultant|Gilead Sciences: Advisor/Consultant|Gilead Sciences: Advisor/Consultant|Merck & Co: Advisor/Consultant|Merck & Co: Advisor/Consultant|Shionogi: Advisor/Consultant|Shionogi Inc.: Advisor/Consultant|Spero Therapeutics: Honoraria|Spero Therapeutics: Honoraria|Vaxart: Stocks/Bonds Bruce M. Jones, Pharm.D., FIDSA, BCPS, AbbVie: Advisor/Consultant|AbbVie: Honoraria|La Jolla: Honoraria|Melinta: Advisor/Consultant|Paratek: Honoraria|Regeneron: Honoraria.

1841. Incidence and Predictors of Complications in Gram Negative Bloodstream Infection

Background

The incidence of complications in Gram negative bloodstream infection (GN-BSI) is not clearly defined. This retrospective cohort study evaluates the incidence of complications within 90 days of GN-BSI and examines the predictors for these complications.

Methods

Hospitalized adult patients with monomicrobial GN-BSI at Prisma Health-Midlands hospitals in South Carolina between 1/1/2012 and 6/30/2015 were evaluated. Complications of GN-BSI were defined as endocarditis, septic arthritis, osteomyelitis, spinal infections, deep seated abscesses, and recurrent GN-BSI within 90 days of the initial episode. Clinical and microbiological variables were assessed as potential risk factors for complications, including initial response to antimicrobial therapy within the first 72-96 hours of GN-BSI using the early clinical failure criteria. Kaplan-Meier analysis and multivariate Cox proportional hazards regression were used to examine the incidence and risk factors of complicated GN-BSI, respectively.

Results

A total 752 patients with GN-BSI were included in the study. The median age was 66 years and 380 (50.6%) were women. The urinary tract was the most common source of GN-BSI (378; 50.2%) and Escherichia coli was the most common bacteria (375; 49.9%). Overall, 13.9% developed complications within 90 days of GN-BSI. The median time to identification of these complications was 5.2 days from the index GN-BSI (interquartile range 1-28 days). The incidence of complications was notably higher in BSI due to Serratia species (39.7%), Proteus mirabilis (35.7%), and Pseudomonas aeruginosa (21.5%) than other bacteria (11.1%; log-rank p< 0.001). Independent risk factors for complications included early clinical failure criteria, non-urinary source, presence of indwelling prosthetic devices, BSI due to Serratia species, P. mirabilis or P. aeruginosa, and persistent GN-BSI (Table).

Conclusion

At least 13.9% of patients developed complications within 90 days of GN-BSI. Risk of development of complications may be predicted by specific host and microbiological factors. Stratification of patients based on these risk factors may aid in identifying patients requiring further diagnostic work up for early detection of complications.

Disclosures

Julie Ann Justo, PharmD, MS, FIDSA, BCPS-AQ ID, bioMerieux: Honoraria|bioMerieux: Honoraria|Entasis Therapeutics: Advisor/Consultant|Entasis Therapeutics: Advisor/Consultant|Gilead Sciences: Advisor/Consultant|Gilead Sciences: Advisor/Consultant|Merck & Co: Advisor/Consultant|Merck & Co: Advisor/Consultant|Shionogi: Advisor/Consultant|Shionogi Inc.: Advisor/Consultant|Spero Therapeutics: Honoraria|Spero Therapeutics: Honoraria|Vaxart: Stocks/Bonds Julie Ann Justo, PharmD, MS, FIDSA, BCPS-AQ ID, bioMerieux: Honoraria|bioMerieux: Honoraria|Entasis Therapeutics: Advisor/Consultant|Entasis Therapeutics: Advisor/Consultant|Gilead Sciences: Advisor/Consultant|Gilead Sciences: Advisor/Consultant|Merck & Co: Advisor/Consultant|Merck & Co: Advisor/Consultant|Shionogi: Advisor/Consultant|Shionogi Inc.: Advisor/Consultant|Spero Therapeutics: Honoraria|Spero Therapeutics: Honoraria|Vaxart: Stocks/Bonds P. Brandon Bookstaver, PharmD, Spero Therapeutics: Advisor/Consultant.

408. Benchmarking the Use of New β-lactams Utilizing a Novel Metric of Microbiological Burden

Background

Several methods are used to account for various hospital characteristics when comparing antimicrobial use (AU) between heterogenous hospitals. Recently, a new antimicrobial stewardship metric that adjusts AU by microbiological burden (a-AU) of the bacteria was proposed (Figure 1). It accounts for the resistant phenotypes observed at a given institution, allowing for a more balanced comparison of AU across hospitals. This multicenter retrospective cohort study examined the use of new β-lactams for Gram-negative bacteria (GNB) with difficult-to-treat resistance (DTR) by both AU and adjusted (a-AU) metrics in the southeastern United States.

Methods

AU of new β-lactams was determined in 9 hospitals within the Southeastern Research Group Endeavor (SERGE-45) between 2015 to 2020. New β-lactams included ceftolozane/tazobactam, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/cilastatin/relebactam, and cefiderocol. AU was adjusted for prevalence of GNB with DTR including Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter species. DTR was defined as nonsusceptibility to all of the following: cefepime or ceftazidime, levofloxacin or ciprofloxacin, meropenem or imipenem, and piperacillin/tazobactam if tested. Hospitals were ranked by AU and a-AU from lowest to highest. Descriptive statistics were utilized.

Results

The cumulative mean AU and a-AU from 2015 to 2020 were 1.96 (range 0.10 to 6.44) and 2.3 (range 0.20 to 8.05) days of therapy (DOT)/1000 patient days, respectively (Figure 2). After adjusting for the prevalence of GNB with DTR, 6 hospitals moved by at least 1 position in ranking (2 hospitals moved up; 4 hospitals moved down) and 1 hospital moved by at least 2 positions in ranking.

Conclusion

Overall, the AU of new β-lactams increased after adjusting for the local microbiological burden suggests a potential higher use of antibiotics in relationship to the observed prevalence of GNB with DTR. More than half of the hospitals had a shift in ranking after microbiological adjustment reflecting a more balanced comparison of antibiotic use across heterogenous hospitals.

Disclosures

P. Brandon Bookstaver, PharmD, Spero Therapeutics: Advisor/Consultant Julie Ann Justo, PharmD, MS, FIDSA, BCPS-AQ ID, bioMerieux: Honoraria|bioMerieux: Honoraria|Entasis Therapeutics: Advisor/Consultant|Entasis Therapeutics: Advisor/Consultant|Gilead Sciences: Advisor/Consultant|Gilead Sciences: Advisor/Consultant|Merck & Co: Advisor/Consultant|Merck & Co: Advisor/Consultant|Shionogi: Advisor/Consultant|Shionogi Inc.: Advisor/Consultant|Spero Therapeutics: Honoraria|Spero Therapeutics: Honoraria|Vaxart: Stocks/Bonds Julie Ann Justo, PharmD, MS, FIDSA, BCPS-AQ ID, bioMerieux: Honoraria|bioMerieux: Honoraria|Entasis Therapeutics: Advisor/Consultant|Entasis Therapeutics: Advisor/Consultant|Gilead Sciences: Advisor/Consultant|Gilead Sciences: Advisor/Consultant|Merck & Co: Advisor/Consultant|Merck & Co: Advisor/Consultant|Shionogi: Advisor/Consultant|Shionogi Inc.: Advisor/Consultant|Spero Therapeutics: Honoraria|Spero Therapeutics: Honoraria|Vaxart: Stocks/Bonds Bruce M. Jones, Pharm.D., FIDSA, BCPS, AbbVie: Advisor/Consultant|AbbVie: Honoraria|La Jolla: Honoraria|Melinta: Advisor/Consultant|Paratek: Honoraria|Regeneron: Honoraria.

Temporal Association between Influenza Vaccination Coverage and Ambulatory Antibiotic Use in Children

In this population-based retrospective cohort study, increased influenza vaccination coverage was temporally associated with a reduction in ambulatory antibiotic use in children. After adjustment for yearly vaccine effectiveness, antibiotic prescription rate declined by 3/1000 person-months for each 1% increase in influenza vaccination coverage between 2012 and 2017 in South Carolina (P < 0.001).

It is time to define an organizational model for the prevention and management of infections along the surgical pathway: a worldwide cross-sectional survey

BACKGROUND

The objectives of the study were to investigate the organizational characteristics of acute care facilities worldwide in preventing and managing infections in surgery; assess participants' perception regarding infection prevention and control (IPC) measures, antibiotic prescribing practices, and source control; describe awareness about the global burden of antimicrobial resistance (AMR) and IPC measures; and determine the role of the Coronavirus Disease 2019 pandemic on said awareness.

METHODS

A cross-sectional web-based survey was conducted contacting 1432 health care workers (HCWs) belonging to a mailing list provided by the Global Alliance for Infections in Surgery. The self-administered questionnaire was developed by a multidisciplinary team. The survey was open from May 22, 2021, and June 22, 2021. Three reminders were sent, after 7, 14, and 21 days.

RESULTS

Three hundred four respondents from 72 countries returned a questionnaire, with an overall response rate of 21.2%. Respectively, 90.4% and 68.8% of participants stated their hospital had a multidisciplinary IPC team or a multidisciplinary antimicrobial stewardship team. Local protocols for antimicrobial therapy of surgical infections and protocols for surgical antibiotic prophylaxis were present in 76.6% and 90.8% of hospitals, respectively. In 23.4% and 24.0% of hospitals no surveillance systems for surgical site infections and no monitoring systems of used antimicrobials were implemented. Patient and family involvement in IPC management was considered to be slightly or not important in their hospital by the majority of respondents (65.1%). Awareness of the global burden of AMR among HCWs was considered very important or important by 54.6% of participants. The COVID-19 pandemic was considered by 80.3% of respondents as a very important or important factor in raising HCWs awareness of the IPC programs in their hospital. Based on the survey results, the authors developed 15 statements for several questions regarding the prevention and management of infections in surgery. The statements may be the starting point for designing future evidence-based recommendations.

CONCLUSION

Adequacy of prevention and management of infections in acute care facilities depends on HCWs behaviours and on the organizational characteristics of acute health care facilities to support best practices and promote behavioural change. Patient involvement in the implementation of IPC is still little considered. A debate on how operationalising a fundamental change to IPC, from being solely the HCWs responsibility to one that involves a collaborative relationship between HCWs and patients, should be opened.

Evaluation of early clinical failure criteria in Enterococcus species bloodstream infection

PURPOSE

Early clinical failure criteria (ECFC) were recently introduced to predict unfavorable outcomes in patients with Gram-negative bloodstream infections (BSI). ECFC include hypotension, tachycardia, tachypnea or mechanical ventilation, altered mental status, and leukocytosis evaluated at 72-96 h after BSI. The aim of this retrospective cohort study was to assess performance of ECFC in predicting 28-day mortality in Enterococcus species BSI.

METHODS

Hospitalized adults with Enterococcus species BSI at Prisma Health hospitals from 1 January 2015 to 31 July 2018 were identified. Multivariate logistic regression was used to determine the association between ECFC and 28-day mortality. Area under the receiver operating characteristic (AUROC) curve was used to measure model discrimination.

RESULTS

Among 157 patients, 28 (18%) died within 28 days of BSI. After adjustments in multivariate model, the risk of 28-day mortality increased in the presence of each additional ECFC (OR 1.6, 95% CI 1.2-2.3, p = 0.005). Infective endocarditis (OR 3.9, 95% CI 1.4-10.7, p = 0.01) was independently associated with 28-day mortality. AUROC curve of ECFC model in predicting 28-day mortality was 0.74 with ECFC of 2 identified as the best breakpoint. Mortality was 8% in patients with ECFC < 2 compared to 33% in those with ECFC ≥ 2 (p < 0.001).

CONCLUSION

ECFC had good discrimination in predicting 28-day mortality in patients with Enterococcus species BSI. These criteria may have utility in future clinical investigations.

Candida parapsilosis bloodstream infection in an immunocompromised host with discordant multiplex polymerase chain reaction and conventional blood culture results: a case report

Prompt treatment of candidemia, especially in immunocompromised hosts, is known to improve outcomes. We present a case of discordance among results of Gram stain, multiplex polymerase chain reaction (PCR)-based rapid diagnostic technology, and conventional cultures that subsequently resulted in delayed therapy and hospitalization. An immunocompromised patient presented to the outpatient oncology clinic with signs and symptoms of systemic infection. Blood cultures were obtained, and Gram stain showed gram-negative rods, while multiplex PCR results (BioFire® FilmArray® BCID 1) returned positive for both Enterobacter cloacae and Candida parapsilosis. Conventional cultures only grew E. cloacae. Because of the discordant results, the primary team elected to give ertapenem monotherapy and defer antifungal therapy. The patient’s symptoms progressed, and 11 days later, the patient was admitted with subsequent positive blood cultures for C. parapsilosis. The patient required a 9-day hospitalization due to complications associated with candidemia. This case highlights the value of understanding and interpretation of rapid diagnostics, shared decision-making in antimicrobial management of high-risk patients, and the important responsibility of antimicrobial stewardship teams across the continuum of care.

Prediction of mortality in Staphylococcus aureus bloodstream infection using quick Pitt bacteremia score

OBJECTIVES

The quick Pitt bacteremia score (qPitt) predicts mortality in patients with serious infections due to gram-negative bacteria. This retrospective cohort study examines utility of qPitt to predict mortality in patients with Staphylococcus aureus bloodstream infection (SAB).

METHODS

Multivariate logistic regression was used to examine risk factors for 28-day mortality in hospitalized adults with SAB at four Prisma Health hospitals in South Carolina, USA from January 2015 to December 2017. Area under receiver operating characteristic curve (AUROC) was used to examine model discrimination.

RESULTS

Among 692 patients with SAB, 305 (44%) had methicillin-resistant S. aureus (MRSA), and 129 (19%) died within 28 days. After adjustment for age, comorbidities, and MRSA, each component of the qPitt was associated with 28-day mortality. There was a 3-fold increase in the risk of 28-day mortality for each one-point increase in qPitt. Predicted 28-day mortality was 3%, 9%, 22%, 45%, and 70% for qPitt of 0, 1, 2, 3, and ≥4, respectively. AUROC of the qPitt in predicting 28-day, 14-day, and in-hospital mortality were 0.80, 0.81, and 0.80, respectively.

CONCLUSIONS

The qPitt predicts mortality with good discrimination in SAB. These results support using qPitt as a measure of acute severity of illness in future studies.

Change in Antimicrobial Use During COVID-19 Pandemic in South Carolina Hospitals: A Multicenter Observational Cohort Study

Objectives

This retrospective cohort study examined the impact of the pandemic on antimicrobial use (AU) in South Carolina hospitals.

Methods

Antimicrobial use in days of therapy (DOT) per 1000 days-present was evaluated in 17 hospitals in South Carolina. Matched-pairs mean difference was used to compare AU during the pandemic (March–June 2020) with that during the same months in 2019 in hospitals that did and did not admit patients with COVID-19.

Results

There was a 6.6% increase in overall AU in the seven hospitals that admitted patients with COVID-19 (from 530.9 to 565.8; mean difference (MD) 34.9 DOT/1000 days-present; 95% CI 4.3, 65.6; P = 0.03). There was no significant change in overall AU in the remaining 10 hospitals that did not admit patients with COVID-19 (MD 6.0 DOT/1000 days-present; 95% CI –55.5, 67.6; P = 0.83). Most of the increase in AU in the seven hospitals that admitted patients with COVID-19 was observed in broad-spectrum antimicrobial agents. A 16.4% increase was observed in agents predominantly used for hospital-onset infections (from 122.3 to 142.5; MD 20.1 DOT/1000 days-present; 95% CI 11.1, 29.1; P = 0.002). There was also a 9.9% increase in the use of anti-methicillin-resistant Staphylococcus aureus (MRSA) agents (from 66.7 to 73.3; MD 6.6 DOT/1000 days-present; 95% CI 2.3, 10.8; P = 0.01).

Conclusion

The COVID-19 pandemic appears to drive overall and broad-spectrum antimicrobial use in South Carolina hospitals admitting patients with COVID-19. Additional antimicrobial stewardship resources are needed to curtail excessive antimicrobial use in hospitals to prevent subsequent increases in antimicrobial resistance and Clostridioides difficile infection rates, given the continuing nature of the pandemic.

A pandemic recap: lessons we have learned

On January 2020, the WHO Director General declared that the outbreak constitutes a Public Health Emergency of International Concern. The world has faced a worldwide spread crisis and is still dealing with it. The present paper represents a white paper concerning the tough lessons we have learned from the COVID-19 pandemic. Thus, an international and heterogenous multidisciplinary panel of very differentiated people would like to share global experiences and lessons with all interested and especially those responsible for future healthcare decision making. With the present paper, international and heterogenous multidisciplinary panel of very differentiated people would like to share global experiences and lessons with all interested and especially those responsible for future healthcare decision making.

Impact of follow up blood cultures on outcomes of patients with community-onset gram-negative bloodstream infection

BACKGROUND

The role of follow up blood cultures (FUBC) in the management of gram-negative bloodstream infection (GN-BSI) remains controversial. This retrospective cohort study examines the association between obtaining FUBC and mortality in GN-BSI.

METHODS

Hospitalized adults with community-onset GN-BSI at Prisma Health-Midlands hospitals in South Carolina, USA from January 1, 2010 to June 30, 2015 were identified. Patients who died or were discharged from hospital within 72 h were excluded to minimize impact of survival and selection biases on results, respectively. Multivariate Cox proportional hazards regression was used to examine association between obtaining FUBC and 28-day all-cause mortality after adjustment for the propensity to obtain FUBC.

FINDINGS

Among 766 patients with GN-BSI, 219 (28.6%) had FUBC obtained and 15 of 219 (6.8%) FUBC were persistently positive. Overall, median age was 67 years, 438 (57%) were women, 457 (60%) had urinary source of infection, and 426 (56%) had BSI due to Escherichia coli. Mortality was significantly lower in patients who had FUBC obtained than in those who did not have FUBC (6.3% vs. 11.7%, log-rank p = 0.03). Obtaining FUBC was independently associated with reduced mortality (hazards ratio 0.47, 95% confidence intervals: 0.23-0.87; p = 0.02) after adjustments for age, chronic comorbidities, acute severity of illness, appropriateness of empirical antimicrobial therapy, and propensity to obtain FUBC.

INTERPRETATION

Improved survival in hospitalized patients with GN-BSI who had FUBC is consistent with the results of recent publications from Italy and North Carolina supporting utilization of FUBC in management of GN-BSI.

FUNDING

This study had no funding source.

Risk and clinical outcomes of acute myocardial infarction and acute ischemic stroke following gram-negative bloodstream infection

Objectives

This retrospective cohort study examines incidence, risk factors, and clinical outcomes of acute myocardial infarction (AMI) and acute ischemic stroke (AIS) within one year of gram-negative bloodstream infection (GN-BSI) based on predefined clinical criteria.

Methods

Hospitalized adults with GN-BSI at Prisma Health-Midlands hospitals in South Carolina, USA from 2010 through 2015 were identified. Kaplan-Meier analysis was used to determine incidence of AMI and AIS within one year after GN-BSI. Multivariate Cox proportional hazards regression models were used to examine risk factors for AMI or AIS and impact on 1-year mortality.

Results

Among 1292 patients with GN-BSI, 263 and 17 developed AMI and AIS within 1-year with incidences of 23.4% and 1.9%, respectively. Majority of AMI were type 2 (164; 62%); 99 patients had type 1 AMI with incidence of 8.9%. Age >65 years (hazard ratio [HR] 1.52, 95% CI: 1.17-1.99), prior coronary artery disease or stroke (HR 1.74, 95% CI: 1.34-2.25), hypertension (HR 1.55, 95% CI: 1.13-2.15), end-stage renal disease (HR 1.52, 95% CI: 1.09-2.08), and quick Pitt bacteremia score (HR 1.55 per point, 95% CI: 1.40-1.72) were predictors of AMI/AIS. Development of type 1 AMI or AIS after GN-BSI was independently associated with increased 1-year mortality (HR 1.47, 95% CI: 1.03-2.07).

Conclusions

AMI and AIS occur frequently within one year of GN-BSI and have negative impact on 1-year survival. Future randomized clinical trials are needed to determine the most effective clinical interventions for prevention of AMI/AIS following BSI in high risk patients and improve survival after these events.

Use of Antibiotics in Chronic Obstructive Pulmonary Disease: What is Their Current Role in Older Patients?

Chronic obstructive pulmonary disease (COPD) has considerable morbidity and mortality in the older adult population. The role of antibiotics in the management of acute exacerbations of COPD (AECOPD) is currently evolving. Despite only mild benefits, most patients with AECOPD in ambulatory settings receive antibiotics based on clinical criteria. Utilization of point-of-care C-reactive protein (CRP) has reduced antibiotic prescriptions by 20% without compromising clinical outcomes. A strict protocol allowing antibiotic use only in patients with clinical criteria and CRP ≥ 20 mg/L has the potential to reduce antibiotic prescriptions for AECOPD in ambulatory settings by nearly 50%. Amoxicillin and doxycycline are commonly prescribed for AECOPD based on a favorable benefit-to-risk ratio. Prophylactic antibiotics have also been used in selected patients with severe COPD and frequent exacerbations. The use of continuous or intermittent azithromycin has demonstrated efficacy in reducing the frequency of AECOPD in this population; however, this approach has potential for the development of antibiotic resistance and adverse effects. The use of azithromycin prophylaxis in older patients with frequent AECOPD should be determined on a case-by-case basis after careful review, discussion, and counseling of the potential benefits and risks. The role of continuous doxycycline and pulsed moxifloxacin prophylaxis for frequent AECOPD remains controversial.

Evaluating appropriateness and diagnostic stewardship opportunities of multiplex polymerase chain reaction gastrointestinal testing within a hospital system

Objective:

This single-center, retrospective, observational cohort study evaluates the appropriateness of the BioFire® FilmArray® Gastrointestinal (GI) multiplex PCR panel testing at a community-teaching hospital.

Methods:

All adult, hospitalized patients at Prisma Health Richland Hospital with a documented GI multiplex PCR panel from 1 April 2015 through 28 February 2018 were included in the analysis. Inappropriate use of the GI panel was defined as a test obtained without documented diarrhea, greater than 2 days of hospitalization, redundant use with other diagnostic tests (e.g. Clostridioides difficile PCR), or laxative use in the preceding 48 h. Antibiotic use and host variables were compared between groups with positive and negative results.

Results:

During the study period, 442 GI panels were obtained, among which 268 (61%) were deemed inappropriate. Primary reasons for inappropriate testing were lack of documented diarrhea (n = 92), greater than 2 days of hospitalization (n = 116), having a duplicate C. difficile PCR test ordered (n = 118), or laxative use in the 48 h before testing (n = 36). A total of 141 (32%) GI panels were positive. The most frequently identified pathogens were C. difficile (51.1%, n = 72), Enteropathogenic Escherichia coli (17.7%, n = 25), and Norovirus GI/GII (12.1%, n = 17). Patients with negative GI panel results were initiated on antibiotics significantly less frequently than those with positive GI panels (62.5% versus 80.2%, p < 0.00001).

Conclusion:

Stewardship opportunities exist to optimize the diagnostic application of the GI multiplex PCR panel.

Role of Early De-escalation of Antimicrobial Therapy on Risk of Clostridioides difficile Infection Following Enterobacteriaceae Bloodstream Infections

BACKGROUND

There is a paucity of data on the effect of early de-escalation of antimicrobial therapy on rates of Clostridioides difficile infection (CDI). This retrospective cohort study evaluated impact of de-escalation from antipseudomonal β-lactam (APBL) therapy within 48 hours of Enterobacteriaceae bloodstream infections (BSIs) on 90-day risk of CDI.

METHODS

Adult patients hospitalized for >48 hours for treatment of Enterobacteriaceae BSI at Palmetto Health hospitals in Columbia, South Carolina, from 1 January 2011 through 30 June 2015 were identified. Multivariable Cox proportional hazards regression was used to examine time to CDI in patients who received >48 hours or ≤48 hours of APBL for empirical therapy of Enterobacteriaceae BSI after adjustment for the propensity to receive >48 hours of APBL.

RESULTS

Among 808 patients with Enterobacteriaceae BSI, 414 and 394 received >48 and ≤48 hours of APBL, respectively. Incidence of CDI was higher in patients who received >48 hours than those who received ≤48 hours of APBL (7.0% vs 1.8%; log-rank P = .002). After adjustment for propensity to receive >48 hours of APBL and other variables in the multivariable model, receipt of >48 hours of APBL (hazard ratio [HR], 3.56 [95% confidence interval {CI}, 1.48-9.92]; P = .004) and end-stage renal disease (HR, 4.27 [95% CI, 1.89-9.11]; P = .001) were independently associated with higher risk of CDI.

CONCLUSIONS

The empirical use of APBL for >48 hours was an independent risk factor for CDI. Early de-escalation of APBL using clinical risk assessment tools or rapid diagnostic testing may reduce the incidence of CDI in hospitalized adults with Enterobacteriaceae BSIs.

Multicenter, Observational Cohort Study Evaluating Third-Generation Cephalosporin Therapy for Bloodstream Infections Secondary to Enterobacter, Serratia, and Citrobacter Species

OBJECTIVES

There is debate on whether the use of third-generation cephalosporins (3GC) increases the risk of clinical failure in bloodstream infections (BSIs) caused by chromosomally-mediated AmpC-producing Enterobacterales (CAE). This study evaluates the impact of definitive 3GC therapy versus other antibiotics on clinical outcomes in BSIs due to Enterobacter, Serratia, or Citrobacter species.

METHODS

This multicenter, retrospective cohort study evaluated adult hospitalized patients with BSIs secondary to Enterobacter, Serratia, or Citrobacter species from 1 January 2006 to 1 September 2014. Definitive 3GC therapy was compared to definitive therapy with other non-3GC antibiotics. Multivariable Cox proportional hazards regression evaluated the impact of definitive 3GC on overall treatment failure (OTF) as a composite of in-hospital mortality, 30-day hospital readmission, or 90-day reinfection.

RESULTS

A total of 381 patients from 18 institutions in the southeastern United States were enrolled. Common sources of BSIs were the urinary tract and central venous catheters (78 (20.5%) patients each). Definitive 3GC therapy was utilized in 65 (17.1%) patients. OTF occurred in 22/65 patients (33.9%) in the definitive 3GC group vs. 94/316 (29.8%) in the non-3GC group (p = 0.51). Individual components of OTF were comparable between groups. Risk of OTF was comparable with definitive 3GC therapy vs. definitive non-3GC therapy (aHR 0.93, 95% CI 0.51-1.72) in multivariable Cox proportional hazards regression analysis.

CONCLUSIONS

These outcomes suggest definitive 3GC therapy does not significantly alter the risk of poor clinical outcomes in the treatment of BSIs secondary to Enterobacter, Serratia, or Citrobacter species compared to other antimicrobial agents.

Impact of Reappraisal of Fluoroquinolone Minimum Inhibitory Concentration Susceptibility Breakpoints in Gram-Negative Bloodstream Isolates

The Clinical Laboratory Standards Institute lowered the fluoroquinolone minimum inhibitory concentration (MIC) susceptibility breakpoints for Enterobacteriaceae and glucose non-fermenting Gram-negative bacilli in January 2019. This retrospective cohort study describes the impact of this reappraisal on ciprofloxacin susceptibility overall and in patients with risk factors for antimicrobial resistance. Gram-negative bloodstream isolates collected from hospitalized adults at Prisma Health-Midlands hospitals in South Carolina, USA, from January 2010 to December 2014 were included. Matched pairs mean difference (MD) with 95% confidence intervals (CI) were calculated to examine the change in ciprofloxacin susceptibility after MIC breakpoint reappraisal. Susceptibility of Enterobacteriaceae to ciprofloxacin declined by 5.2% (95% CI: −6.6, −3.8; p < 0.001) after reappraisal. The largest impact was demonstrated among Pseudomonas aeruginosa bloodstream isolates (MD −7.8, 95% CI: −14.6, −1.1; p = 0.02) despite more conservative revision in ciprofloxacin MIC breakpoints. Among antimicrobial resistance risk factors, fluoroquinolone exposure within the previous 90 days was associated with the largest change in ciprofloxacin susceptibility (MD −9.3, 95% CI: −16.1, −2.6; p = 0.007). Reappraisal of fluoroquinolone MIC breakpoints has a variable impact on the susceptibility of bloodstream isolates by microbiology and patient population. Healthcare systems should be vigilant to systematically adopt this updated recommendation in order to optimize antimicrobial therapy in patients with bloodstream and other serious infections.

Empirical fluoroquinolones versus broad-spectrum beta-lactams for Gram-negative bloodstream infections in the absence of antimicrobial resistance risk factors

OBJECTIVES

Increasing antimicrobial resistance rates limit empirical antimicrobial treatment options for Gram-negative bloodstream infections (GN-BSI). However, antimicrobial resistance may be predicted based on patient-specific risk factors using precision medicine concepts. This retrospective, 1:2 matched cohort examined clinical outcomes in hospitalized adults without major risk factors for antimicrobial resistance receiving empirical fluoroquinolones or broad-spectrum beta-lactams (BSBL) for GN-BSI at Prisma Health-Midlands hospitals in Columbia, SC, USA from January 2010 through June 2015.

METHODS

Multivariable logistic regression was used to examine early treatment failure at 72-96 h from GN-BSI. Cox proportional hazards regression was used to examine 28-day mortality and hospital length of stay (HLOS).

RESULTS

Among 74 and 148 patients receiving empirical fluoroquinolones and BSBL for GN-BSI, respectively, median age was 68 years, 159 (72%) were women, and 152 (68%) had a urinary source of infection. Early treatment failure rates were comparable in fluoroquinolone and BSBL groups (27% vs. 30%, respectively, odds ratio 0.82, 95% confidence intervals [CI] 0.43-1.54, P = 0.53), as well as 28-day mortality (8.9% vs. 9.7%, respectively, hazards ratio [HR] 0.74, 95% CI 0.26-1.90, P = 0.54). Median HLOS was 6.1 days in the fluoroquinolone group and 7.1 days in the BSBL group (HR 0.73, 95% CI 0.54-0.99, P = 0.04). Transition from intravenous to oral therapy occurred sooner in the fluoroquinolone group than in the BSBL group (3.0 vs. 4.9 days, P < 0.001).

CONCLUSIONS

In the absence of antimicrobial resistance risk factors, fluoroquinolones provide an additional empirical treatment option to BSBL for GN-BSI. Shorter HLOS in the fluoroquinolone group may be due to earlier transition from intravenous to oral antimicrobial therapy.

Prediction of trimethoprim/sulfamethoxazole resistance in community-onset urinary tract infections

OBJECTIVES

This study aimed to predict trimethoprim/sulfamethoxazole (SXT) resistance in patients with community-onset urinary tract infection (UTI) due to Enterobacteriaceae based on patient-specific risk factors.

METHODS

This was a retrospective case-control study in Prisma Health facilities in central South Carolina, USA, including three community hospitals, affiliated emergency departments and ambulatory clinics, including adult patients with community-onset UTI due to Enterobacteriaceae (1 April 2015 to 29 February 2016). Multivariate logistic regression was used to examine risk factors for SXT resistance.

RESULTS

Among 351 unique patients with community-onset UTI, 71 (20.2%) had SXT-resistant Enterobacteriaceae urinary isolates. Overall, median age was 64 years and 252 (71.8%) were female. A multivariate model identified prior urinary infection/colonisation with SXT-resistant Enterobacteriaceae (OR=8.58, 95% CI 3.92-18.81; P<0.001) and SXT use within past 12 months (OR=2.58, 95% CI 1.13-5.89; P=0.02) as predictors of SXT resistance among urinary isolates. Most patients with UTI (285; 81.2%) had no risk factors for SXT resistance. SXT resistance rates increased from 13% in the absence of risk factors to 31% in patients with prior SXT use, 66% in those with prior urinary infection/colonisation with SXT-resistant Enterobacteriaceae and 73% in the presence of both risk factors.

CONCLUSION

SXT resistance in Enterobacteriaceae urinary isolates may be predicted based on prior urine culture results and SXT use within the previous year. Utilisation of a patient-specific antibiogram may allow empirical SXT use in patients with community-onset UTI in the absence of risk factors for resistance.

Utility of Combination Antimicrobial Therapy in Adults with Bloodstream Infections due to Enterobacteriaceae and Non-Fermenting Gram-Negative Bacilli Based on In Vitro Analysis at Two Community Hospitals

This study examined the utility of combination therapy for bloodstream isolates of Enterobacteriaceae and non-fermenting Gram-negative bacilli (NFGN) from adults at two community hospitals from January 2010 through to June 2015. Changes to in vitro antimicrobial susceptibilities by adding ciprofloxacin or gentamicin to third-generation cephalosporins (3GC) were examined overall and in patients with risk factors for 3GC resistance. Overall ceftriaxone susceptibility among Enterobacteriaceae was 996/1063 (94%) and 247/295 (84%) in patients with 3GC resistance risk factors. Susceptibilities increased marginally by adding ciprofloxacin or gentamicin (mean difference 2.4% (95% CI 1.5, 3.4) and 3.0% (95% CI 2.0, 4.0), respectively, overall and 5.4% (95% CI 2.8, 8.0) and 7.1% (95% CI 4.2, 10.1), respectively, in patients with risk factors). Eighty-three of 105 (79%) NFGN were susceptible to ceftazidime overall and 20/29 (69%) in patients with prior beta-lactam use. Overall mean increase in susceptibilities was 15.2% (95% CI: 8.3, 22.2) and 17.1% (95% CI: 9.8, 24.5) for ciprofloxacin and gentamicin combinations, respectively; and 27.6% (95% CI: 10.3, 44.9) for either one with recent beta-lactam use. In this setting, empirical combination therapy had limited utility for Enterobacteriaceae bloodstream isolates but provided significant additional antimicrobial coverage to ceftazidime for NFGN, particularly in patients with prior beta-lactam use.

1043. Evaluation of Early Clinical Failure Criteria for Gram-Negative Bloodstream Infections

Background

Early identification of patients at high risk of morbidity and mortality following Gram-negative bloodstream infections (GN-BSI) based on initial clinical course may prompt adjustments to optimize diagnostic and treatment plans. This retrospective cohort study aims to develop early clinical failure criteria (ECFC) to predict unfavorable outcomes in patients with GN-BSI.

Methods

Adults with community-onset GN-BSI who survived hospitalization for at least 96 hours at Palmetto Health hospitals in Columbia, SC, USA from January 1, 2010 to June 30, 2015 were identified. Multivariate logistic regression was used to examine association between clinical variables within 72–96 hours of BSI and unfavorable outcomes (28-day mortality or hospital length of stay >14 days).

Results

Among 766 patients with GN-BSI, 225 (29%) had unfavorable outcomes. After adjustments for Charlson Comorbidity Index and appropriateness of empirical antimicrobial therapy in multivariate model, predictors of unfavorable outcomes included systolic blood pressure <100 mmHg or vasopressor use (adjusted odds ratio [aOR] 1.8, 95% confidence interval [CI] 1.1–2.5), heart rate >100/minute (aOR 1.7, 95% CI 1.1–2.5), respiratory rate ≥22/minute or mechanical ventilation (aOR 2.1, 95% CI 1.4–3.3), altered mental status (aOR 4.5, 95% CI 2.8–7.1), and peripheral WBC count >12 × 10³/mm³ (aOR 2.7, 95% CI 1.8–4.1) at 72–96 hours from index BSI. Area under receiver operating characteristic curve of ECFC model in predicting unfavorable outcomes was 0.77 (0.84 and 0.71 in predicting 28-day mortality and prolonged hospitalization separately, respectively). Predicted 28-day mortality increased from 1% in patients with no ECFC to 3%, 7%, 16%, 32%, and 54% in presence of each additional criterion (P < 0.001). Predicted hospital length of stay was 7.5 days in patients without any ECFC and increased by 4.0 days (95% CI 3.1–4.9, P < 0.001) in presence of each additional criterion.

Conclusion

Risk of 28-day mortality or prolonged hospitalization can be estimated within 72–96 hours of GN-BSI using ECFC. These criteria may have utility in future clinical research in assessing response to antimicrobial therapy based on a standard evidence-based definition of early clinical failure.

Disclosures

P. B. Bookstaver, CutisPharma: Scientific Advisor, <$1,000. Melinta Therapeutics: Speaker’s Bureau, <$1,000.

975. Clostridium difficile Infection and Antibiotic Prescription Rates in the Community: Explaining the Gender Gap

Background

Previous studies have reported higher incidence rates of community-associated Clostridium difficile infection (CA-CDI) in women than in men. This cross-sectional population-based study examines whether this difference in CA-CDI rates across genders is driven by or independent of antibiotic use.

Methods

Medicaid and State Employee Health Plan pharmacy claims for outpatient oral antibiotics and associated medical claims were utilized for estimation of community antibiotic prescription rates in South Carolina population 18 to 64 years of age from January 1, 2015 to December 31, 2015. CA-CDI cases were identified from National Healthcare Safety Network (NHSN) and South Carolina Infectious Disease and Outbreak Network (SCION) through complete enumeration of South Carolina population of the same age and study period as above. Incidence rates of CA-CDI were reported in both men and women 18–39 and 40–64 years of age before and after adjustments for antibiotic prescription rates in the same gender and age group. The 95% confidence intervals (CI) were calculated to examine statistical difference in incidence rates across genders within the same age group.

Results

During the calendar year 2015, a total of 1,564 CA-CDI cases were identified in South Carolina residents 18–64 years of age. The incidence rate of CA-CDI per 100,000 person-years was higher in women than in men in age groups 18–39 years (37.3 [95% CI: 32.8–41.8] vs. 21.0 [95% CI: 17.6–24.4]) and 40–64 years (86.4 [95% CI: 80.1–92.8] vs. 56.6 [95% CI: 51.2–61.9]. Similarly, antibiotic prescription rates per 100 person-years were higher in women than men in the 2 respective age groups (118.8 [95% CI: 118.3–119.3] vs. 54.3 [95% CI: 53.9–54.8] and 130.4 [95% CI: 129.8–130.9] vs. 83.8 [95% CI: 83.3–84.4]. After adjustments for antibiotic prescriptions, there was no significant difference in the incidence rates of CA-CDI per 100,000 prescriptions between women and men 18–39 years of age (31.4 [95% CI: 27.6–35.2] vs. 38.6 [95% CI: 32.4–44.8] and 40–64 years old (66.3 [95% CI 61.5–71.2] vs. 67.5 [95% CI: 61.1–73.8]).

Conclusion

Higher crude incidence rates of CA-CDI in women are likely due to higher outpatient antibiotic prescription rates in women when compared with men.

Disclosures

P. B. Bookstaver, CutisPharma: Scientific Advisor, <$1,000. Melinta Therapeutics: Speaker’s Bureau, <$1,000.

475. Burden of Clostridium difficile Infection in South Carolina: A Population-Based Study

Background

Methods

Results

Conclusion

Disclosures

A Global Declaration on Appropriate Use of Antimicrobial Agents across the Surgical Pathway

This declaration, signed by an interdisciplinary task force of 234 experts from 83 different countries with different backgrounds, highlights the threat posed by antimicrobial resistance and the need for appropriate use of antibiotic agents and antifungal agents in hospitals worldwide especially focusing on surgical infections. As such, it is our intent to raise awareness among healthcare workers and improve antimicrobial prescribing. To facilitate its dissemination, the declaration was translated in different languages.

Microbiologic Predictors of Pelvic Osteomyelitis Related to Decubitus Ulcers

Background

Management of pelvic osteomyelitis related to decubitus ulcers (PODU) remains challenging, whereas definitive therapy is based on blood, bone, or deep tissue cultures, empirical therapy prior to culture results may be indicated in patients with sepsis or cellulitis surrounding PODU. The objective of this retrospective case series is to develop an institutional protocol for empirical therapy of PODU when indicated based on local microbiology results.

Methods

Hospitalized adults with PODU from 1 August 2005 to 1 August 2015 at Palmetto Health hospitals in Columbia, SC were identified. PODU was defined based on clinical, radiographic, and microbiology criteria. Descriptive statistical methods (Fisher’s exact) were used for preliminary analysis.

Results

Seventy-five cases with PODU were included with a mean age of 53 years and male predominance (48; 64%). The most common comorbidities were paraplegia (45, 60%), diabetes (23, 31%) and previous strokes (17, 23%). Forty-nine cases (65%) received antibiotics within a year of PODU. Prior infections or colonization with P. aeruginosa within the past year was present in 24/75 (32%) cases. Most cases had multiple sources of cultures: blood (61; 81%), bone/deep tissue (37; 49%), and/or superficial (73; 97%). Among a total of 99 clinical isolates, 56 (57%) were Gram-positive cocci (GPC) and 43 (43%) were Gram-negative bacilli (GNB). The most common organisms were Enterobacteriaceae (26; 26%), coagulase negative staphylococci (CONS) (20, 20%), Stapylococcus aureus (19, 19%), [12 (12%) methicillin-resistant S. aureus], and P. aeruginosa (9, 9%). Of the Enterobacteriaceae, 69% (18/26) were susceptible to ciprofloxacin and 88% (23/26) to ceftriaxone. All cases (9/9) of PODU due to P. aeruginosa had a prior infection/colonization with P. aeruginosa within 1 year as compared with 15/66 (23%) in those with PODU due to other organisms (P = 0.001).

Conclusion

The microbiology of PODU is diverse (including GPC and GNB). Prior positive P. aeruginosa culture was a predictor of P. aeruginosa PODU. When empirical antimicrobial therapy is indicated, data support the use of intravenous vancomycin plus ceftriaxone in the absence of prior infection/colonization with P. aeruginosa, or intravenous vancomycin plus an anti-pseudomonal agent in the presence of prior P. aeruginosa within the past year.

Disclosures

All authors: No reported disclosures.

Combination therapy vs. monotherapy for Gram-negative bloodstream infection: matching by predicted prognosis

The utility of empirical combination antimicrobial therapy for Gram-negative bloodstream infection (BSI) remains unclear. This retrospective, quasi-experimental matched cohort study examined the impact of empirical combination therapy on mortality in patients with Gram-negative BSI. Hospitalized adults with Gram-negative BSI from 1 January 2010 to 31 December 2013 at Palmetto Health Hospitals in Columbia, SC, USA were identified. Patients receiving combination therapy or beta-lactam monotherapy were matched 1:1 based on age, sex and Bloodstream Infection Mortality Risk Score (BSIMRS). Multivariate Cox proportional hazards regression with propensity score adjustment was used to examine overall 28-day mortality and within predefined BSIMRS categories (<5 and ≥5). A total of 380 patients receiving combination therapy or monotherapy for Gram-negative BSI were included in the study. Median age was 66 years and 204 (54%) were female. Overall, 28-day mortality in patients who received combination therapy and monotherapy was 13% and 15%, respectively (P = 0.51). After stratification by BSIMRS, mortality in both combination therapy and monotherapy groups was 1.1% in patients with BSIMRS <5 (P = 0.98) and 27% and 32%, respectively, in patients with BSIMRS ≥5 (P = 0.47). After adjusting for propensity to receive combination therapy, risk of mortality was not significantly different for combination therapy compared to monotherapy (hazard ratio [HR] 0.90, 95% confidence interval [CI] 0.51-1.60). This finding persisted for both subgroups of BSIMRS <5 (HR 0.96, 95% CI 0.04-24.28) and BSIMRS ≥5 (HR 0.83, 95% CI 0.46-1.48). There is no survival benefit from empirical combination therapy over monotherapy in patients with Gram-negative BSI, regardless of predicted prognosis at initial presentation.

Development of Institutional Guidelines for Management of Gram-Negative Bloodstream Infections: Incorporating Local Evidence

Background: Appropriate empirical antimicrobial therapy is associated with improved outcomes of patients with Gram-negative bloodstream infections (BSI). Objective: Development of evidence-based institutional management guidelines for empirical antimicrobial therapy of Gram-negative BSI. Methods: Hospitalized adults with Gram-negative BSI in 2011-2012 at Palmetto Health hospitals in Columbia, SC, USA, were identified. Logistic regression was used to examine the association between site of infection acquisition and BSI due to Pseudomonas aeruginosa or chromosomally mediated AmpC-producing Enterobacteriaceae (CAE). Antimicrobial susceptibility rates of bloodstream isolates were stratified by site of acquisition and acute severity of illness. Retained antimicrobial regimens had predefined susceptibility rates ≥90% for noncritically ill and ≥95% for critically ill patients. Results: Among 390 patients, health care-associated (odds ratio [OR]: 3.0, 95% confidence interval [CI]: 1.5-6.3] and hospital-acquired sites of acquisition (OR: 3.7, 95% CI: 1.6-8.4) were identified as risk factors for BSI due to P aeruginosa or CAE, compared with community-acquired BSI (referent). Based on stratified bloodstream antibiogram, ceftriaxone met predefined susceptibility criteria for community-acquired BSI in noncritically ill patients (95%). Cefepime and piperacillin-tazobactam monotherapy achieved predefined susceptibility criteria in noncritically ill (95% both) and critically ill patients with health care-associated and hospital-acquired BSI (96% and 97%, respectively) and critically ill patients with community-acquired BSI (100% both). Conclusions: Incorporation of site of acquisition, local antimicrobial susceptibility rates, and acute severity of illness into institutional guidelines provides objective evidence-based approach for optimizing empirical antimicrobial therapy for Gram-negative BSI. The suggested methodology provides a framework for guideline development in other institutions.

Optimal duration of antimicrobial therapy for uncomplicated Gram-negative bloodstream infections

PURPOSE

Optimal antimicrobial treatment duration for Gram-negative bloodstream infection (BSI) remains unclear. This retrospective cohort study examined effectiveness of short (7-10 days) and long (>10 days) courses of antimicrobial therapy for uncomplicated Gram-negative BSI.

METHODS

Hospitalized adults with uncomplicated Gram-negative BSI at Palmetto Health hospitals in Columbia SC, USA from January 1, 2010 to December 31, 2013 were identified. Multivariate Cox proportional hazards regression with propensity score adjustment was used to examine risk of treatment failure in the two groups.

RESULTS

During the study period, 117 and 294 patients received short and long courses of antimicrobial therapy for uncomplicated Gram-negative BSI, respectively. Overall, the median age was 67 years, 258 (63%) were women, 282 (69%) had urinary source of infection, and 271 (66%) had BSI due to Escherichia coli. The median duration of antimicrobial therapy was 8.5 and 13.3 days in the short and long treatment groups, respectively. After adjustment for the propensity to use a short course of therapy, risk of treatment failure was higher in patients receiving short compared to long courses of antimicrobial agents (HR 2.60, 95% CI: 1.20-5.53, p = 0.02). Other risk factors for treatment failure included liver cirrhosis (HR 5.83, 95% CI: 1.89-15.02, p = 0.004) and immune compromised status (HR 4.30, 95% CI: 1.57-10.80, p = 0.006). Definitive antimicrobial therapy with intravenous or highly bioavailable oral agents was associated with reduced risk of treatment failure (HR 0.33, 95% CI: 0.14-0.73, p = 0.006).

CONCLUSIONS

The current results support common clinical practice of 2 weeks of antimicrobial therapy for uncomplicated Gram-negative BSI.