Time to First Culture Positivity Among Critically Ill Adults With Methicillin-Resistant Staphylococcus aureus Growth in Respiratory or Blood Cultures

Swab Testing to Optimize Pneumonia treatment with empiric Vancomycin (STOP-Vanc): study protocol for a randomized controlled trial

BACKGROUND

Vancomycin, an antibiotic with activity against methicillin-resistant Staphylococcus aureus (MRSA), is frequently included in empiric treatment for community-acquired pneumonia (CAP) despite the fact that MRSA is rarely implicated in CAP. Conducting polymerase chain reaction (PCR) testing on nasal swabs to identify the presence of MRSA colonization has been proposed as an antimicrobial stewardship intervention to reduce the use of vancomycin. Observational studies have shown reductions in vancomycin use after implementation of MRSA colonization testing, and this approach has been adopted by CAP guidelines. However, the ability of this intervention to safely reduce vancomycin use has yet to be tested in a randomized controlled trial.

METHODS

STOP-Vanc is a pragmatic, prospective, single center, non-blinded randomized trial. The objective of this study is to test whether the use of MRSA PCR testing can safely reduce inappropriate vancomycin use in an intensive care setting. Adult patients with suspicion for CAP who are receiving vancomycin and admitted to the Medical Intensive Care Unit at Vanderbilt University Medical Center will be screened for eligibility. Eligible patients will be enrolled and randomized in a 1:1 ratio to either receive MRSA nasal swab PCR testing in addition to usual care (intervention group), or usual care alone (control group). PCR testing results will be transmitted through the electronic health record to the treating clinicians. Primary providers of intervention group patients with negative swab results will also receive a page providing clinical guidance recommending discontinuation of vancomycin. The primary outcome will be vancomycin-free hours alive, defined as the expected number of hours alive and free of the use of vancomycin within the first 7 days following trial enrollment estimated using a proportional odds ratio model. Secondary outcomes include 30-day all-cause mortality and time alive off vancomycin.

DISCUSSION

STOP-Vanc will provide the first randomized controlled trial data regarding the use of MRSA nasal swab PCR testing to guide antibiotic de-escalation. This study will provide important information regarding the effect of MRSA PCR testing and antimicrobial stewardship guidance on clinical outcomes in an intensive care unit setting.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06272994. Registered on February 22, 2024.

Swab Testing to Optimize Pneumonia treatment with empiric Vancomycin (STOP-Vanc): study protocol for a randomized controlled trial

Background

Vancomycin, an antibiotic with activity against Methicillin-resistant Staphylococcus aureus (MRSA), is frequently included in empiric treatment for community-acquired pneumonia (CAP) despite the fact that MRSA is rarely implicated in CAP. Conducting polymerase chain reaction (PCR) testing on nasal swabs to identify the presence of MRSA colonization has been proposed as an antimicrobial stewardship intervention to reduce the use of vancomycin. Observational studies have shown reductions in vancomycin use after implementation of MRSA colonization testing, and this approach has been adopted by CAP guidelines. However, the ability of this intervention to safely reduce vancomycin use has yet to be tested in a randomized controlled trial.

Methods

STOP-Vanc is a pragmatic, prospective, single center, non-blinded randomized trial. Adult patients with suspicion for CAP who are receiving vancomycin and admitted to the Medical Intensive Care Unit at Vanderbilt University Medical Center will be screened for eligibility. Eligible patients will be enrolled and randomized in a 1:1 ratio to either receive MRSA nasal swab PCR testing in addition to usual care (intervention group), or usual care alone (control group). PCR testing results will be transmitted through the electronic health record to the treating clinicians. Primary providers of intervention group patients with negative swab results will also receive a page providing clinical guidance recommending discontinuation of vancomycin. The primary outcome will be vancomycin-free hours alive, defined as the number of hours alive and free of the use of vancomycin within the first seven days following trial enrollment estimated using a proportional odds ratio model. Secondary outcomes include 30-day all-cause mortality and time alive off vancomycin.

Discussion

STOP-Vanc will provide the first randomized controlled trial data regarding the use of MRSA nasal swab PCR testing to guide antibiotic de-escalation. This study will provide important information regarding the effect of MRSA PCR testing and antimicrobial stewardship guidance on clinical outcomes in an intensive care unit setting.

Trial registration

This trial was registered on ClinicalTrials.gov on February 22, 2024. (ClinicalTrials.gov identifier: NCT06272994).

Advances in Sepsis Care

This review article summarizes current scientific evidence regarding the treatment of sepsis. We highlight recent advances in sepsis management with a focus on antibiotics, fluids, vasopressors, and adjunctive therapies such as corticosteroids and renal replacement therapy.

Time to blood, respiratory and urine culture positivity in the intensive care unit: Implications for de-escalation

Objectives

Concern for late detection of bacterial pathogens is a barrier to early de-escalation efforts. The purpose of this study was to assess blood, respiratory and urine culture results at 72 h to test the hypothesis that early negative culture results have a clinically meaningful negative predictive value.

Methods

We retrospectively reviewed all patients admitted to the medical intensive care unit between March 2012 and July 2018 with blood cultures obtained. Blood, respiratory and urine culture results were assessed for time to positivity, defined as the time between culture collection and preliminary species identification. The primary outcome was the negative predictive value of negative blood culture results at 72 h. Secondary outcomes included sensitivity, specificity, positive predictive value and negative predictive value of blood, respiratory and urine culture results.

Results

The analysis included 1567 blood, 514 respiratory and 1059 urine cultures. Of the blood, respiratory and urine cultures ultimately positive, 90.3%, 76.2% and 90.4% were positive at 72 h. The negative predictive value of negative 72-h blood, respiratory and urine cultures were 0.99, 0.82 and 0.97, respectively. Antibiotic de-escalation had good specificity, positive predictive value and negative predictive value for finalized negative cultures.

Conclusion

Negative blood and urine culture results at 72 h had a high negative predictive value. These findings have important ramifications for antimicrobial stewardship efforts and support protocolized re-evaluation of empiric antibiotic therapy at 72 h. Caution should be used in patients with clinically suspected pneumonia, since negative respiratory culture results at 72 h were weakly predictive of finalized negative cultures.

Retrospective Study of Acute Kidney Injury Incidence in Patients with Newly Diagnosed Acute Promyelocytic Leukemia

Purpose

Acute promyelocytic leukemia (APL) constitutes 5–10% of all cases of newly diagnosed acute myeloid leukemia. However, data on the epidemiology and risk factors for acute kidney injury (AKI) in patients with newly diagnosed APL are lacking. This study determined the incidence rate of AKI during induction chemotherapy for patients with newly diagnosed APL and the risk factors for AKI.

Patients and Methods

We conducted a retrospective observational study of patients with newly diagnosed APL in the Shonan Kamakura General Hospital between April 2004 and April 2020. Data of 27 patients with newly diagnosed APL were analyzed. The patients were classified as no AKI and AKI stages 1, 2 or 3.

Results

The incidence rate of AKI during induction chemotherapy was 40% (11/27). Among patients who developed AKI, four patients experienced AKI stage 3, and two patients required renal replacement therapy. No significant differences were found in the white blood cell count and baseline renal function between the groups; however, D-dimer and C-reactive protein levels upon admission were significantly higher in patients with AKI than in patients without AKI. Among patients who developed AKI, in hospital mortality at 90 days was 36% (4/11), which was significantly higher than among patients without AKI (p = 0.02). Patients who developed AKI were administered vancomycin more frequently, while almost all blood culture results were negative.

Conclusion

Incidence of AKI development in patients with newly diagnosed APL during induction chemotherapy was approximately 40%. Moreover, patients who developed AKI tended to be administered vancomycin more frequently. Unnecessary use of vancomycin should be avoided in patients with newly diagnosed APL, and using alternative non-nephrotoxic drugs should be considered for patients at risk of AKI.

Time to First Culture Positivity for Gram-Negative Rods Resistant to Ceftriaxone in Critically Ill Adults

BACKGROUND

The optimal timing for the de-escalation of broad-spectrum antibiotics with activity against Pseudomonas aeruginosa and resistant Gram-negative rods (GNRs) in critically ill adults remains unknown.

RESEARCH QUESTION

We tested the hypothesis that cultures will identify GNRs that ultimately demonstrate resistance to ceftriaxone within 48 hours, potentially allowing safe de-escalation at this time point.

STUDY DESIGN AND METHODS

We conducted a secondary analysis of data from the Isotonic Solutions and Major Adverse Renal Events Trial: a pragmatic, cluster-randomized, multiple-crossover trial comparing balanced crystalloids versus saline for intravenous fluid administration in 15,802 critically ill adults at 5 intensive care units (ICUs) at Vanderbilt University Medical Center in Nashville, TN, USA. The primary endpoint was the time-to-positivity of respiratory and blood cultures that ultimately demonstrated growth of GNRs resistant to ceftriaxone. Multivariable logistic regression modeling was used to examine risk factors for the growth of cultures after 48 hours.

RESULTS

A total of 524 respiratory cultures had growth of GNRs, of which 284 (54.2%) had resistance to ceftriaxone. A total of 376 blood cultures grew GNRs, of which 70 (18.6%) had resistance to ceftriaxone. At 48 hours, 87% of respiratory cultures and 85% of blood cultures that ultimately grew GNRs resistant to ceftriaxone had demonstrated growth. Age, gender, predicted risk of inpatient mortality and prior use of antibiotics did not predict the growth of cultures after 48 hours.

INTERPRETATION

Among a cohort of critically ill adults, 13% of respiratory cultures and 15% of blood cultures that ultimately grew GNRs resistant to ceftriaxone did not demonstrate growth until at least 48 hours after collection. Further work is needed to determine the ideal time for critically ill adults to de-escalate from broad-spectrum antibiotics targeting Pseudomonas aeruginosa and extended-spectrum β-lactamase-producing gram-negative pathogens.