Effect of rapid methicillin-resistant Staphylococcus aureus nasal polymerase chain reaction screening on vancomycin use in the intensive care unit

Assessing the Predictive Value of Methicillin-Resistant Staphylococcus aureus Nares Colonization Among Transplant Recipients and Patients With Neutropenia

Background

Methicillin-resistant Staphylococcus aureus (MRSA) nares screening has been shown to be a powerful antibiotic stewardship tool for MRSA infections within 7 days of screening across a variety of anatomical locations given the high negative predictive value (NPV). However, the utility outside of 7 days and among transplant recipients and patients with neutropenia is less clear.

Methods

This was a retrospective cohort study across Veterans Affairs medical centers in the United States from 1 January 2007 to 1 January 2023 of patients tested for MRSA colonization and who had a subsequent positive bacterial culture within 28 days of MRSA sc---reening. Sensitivity, specificity, positive predictive value, and NPV were calculated across different time points and anatomical culture locations.

Results

The cohort consisted of 686 174 patients, 6 277 437 MRSA nares tests, and 2 446 766 positive bacterial cultures within 28 days of MRSA testing. The NPV of MRSA nares screening for ruling out a MRSA infection within 28 days was 95.8% across all anatomical culture sites. The NPV was 97.9% among patients with neutropenia and 97.5% in solid organ and hemopoietic stem cell transplant recipients.

Conclusions

MRSA nares screening can reliably be used for de-escalation of anti-MRSA therapy within 28 days of bacterial culture for all patients, including solid organ and hematopoietic transplant recipients and patients with neutropenia.

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).

Utility of Methicillin-Resistant Staphylococcus aureus Nasal PCR Testing in Pediatric Patients With Suspected Respiratory Infections

Observational studies in adults suggest nasal methicillin-resistant Staphylococcus aureus (MRSA) swabs have a high negative predictive value (NPV) for ruling out MRSA pneumonia, however, pediatric data are limited. This retrospective study of 505 pediatric patients found a 99.8% NPV among children with suspected respiratory infections.

Approaches to Reduce Use and Duration of Anti-MRSA Agents for Antimicrobial Stewardship Programs: A Review of Recent Literature

Antimicrobial stewardship programs (ASPs) have the potential to effectively deescalate unnecessary methicillin-resistant Staphylococcus aureus (MRSA) coverage. This review summarizes literature published from 2014 through 2021 describing contemporary ASP methods and their resulting effectiveness at reducing anti-MRSA agent use (ie vancomycin, linezolid, daptomycin, ceftaroline, and clindamycin). This review of the literature examined the following strategies, which had reports of success in either decreasing the use or duration of anti-MRSA agents: prospective review and feedback, antibiotic timeouts, health system or department protocol changes, polymerase chain reaction (PCR) and rapid testing of patient samples. Most of the current literature continue to support most ASP interventions including antibiotic timeouts, pathways, and molecular testing including MRSA nasal PCRs and rapid diagnostic testing can be successful at reducing unnecessary anti-MRSA use.

Comparison of Methicillin-Resistant Staphylococcus aureus Nasal Screening Predictive Value in the Intensive Care Unit and General Ward

BACKGROUND

The clinical utility of methicillin-resistant Staphylococcus aureus (MRSA) nasal screening appears promising for antimicrobial stewardship programs. However, a paucity of data remains on the diagnostic performance of culture-based MRSA screen in the intensive care unit (ICU) for pneumonia and bacteremia.

OBJECTIVE

The objective of this study was to compare the predictive value of culture-based MRSA nasal screening for pneumonia and bacteremia in ICU and general ward patients.

METHODS

This multicenter, retrospective study was conducted over a 23-month period. Adult patients with MRSA nasal screening ≤48 hours of collecting a respiratory and/or blood culture with concurrent initiation of anti-MRSA therapy were included. The primary endpoint was to compare the negative predictive value (NPV) associated with culture-based MRSA nasal screening between ICU and general ward patients with suspected pneumonia.

RESULTS

A total of 5106 patients representing the ICU (n = 2515) and general ward (n = 2591) were evaluated. The NPV of the MRSA nares for suspected pneumonia was not significantly different between ICU and general ward patient populations (98.3% and 97.6%, respectively; P = 0.41). The MRSA nares screening tool also had a high NPV for suspected bacteremia in ICU (99.8%) and general ward groups (99.7%) (P = 0.56). The overall positive MRSA nares rates in the ICU and general ward patient populations were 9.1% and 8.2%, respectively (P = 0.283). Moreover, MRSA-positive respiratory and blood cultures among ICU patients were 5.8% and 0.8%, respectively.

CONCLUSION AND RELEVANCE

Our findings support the routine use of MRSA nasal screening using the culture-based method in ICU patients with pneumonia. Further research on the clinical performance for MRSA bacteremia in the ICU is warranted.

Evaluation of Anti-Methicillin-Resistant Staphylococcus aureus (MRSA) Prescribing Habits in Patients with a Positive MRSA Nasal Swab in the Absence of Positive Cultures

Methicillin-resistant Staphylococcus aureus (MRSA) polymerase chain reaction (PCR) nasal swabs are guideline-recommended de-escalation tools in certain patients with pneumonia. Prior studies have demonstrated reduced anti-MRSA therapy with negative results, but the impact on durations of therapy has been poorly elucidated in patients with positive PCRs. The objective of this review was to evaluate anti-MRSA treatment durations in patients with a positive MRSA PCR in the absence of MRSA growth on culture. This was a single-center, retrospective observational study evaluating 52 hospitalized, adult patients receiving anti-MRSA therapy with positive MRSA PCRs. The overall median duration of anti-MRSA therapy was five days, including a median of four days after PCR results. This was consistent among intensive care unit (ICU) and non-ICU patient populations and in patients with suspected community-acquired pneumonia (CAP). Among patients with hospital-acquired pneumonia (HAP), the median duration of anti-MRSA therapy was seven days, with a median of six days after PCR results. Overall, patients received a median duration of anti-MRSA therapy that would constitute a full treatment course for many respiratory infections, which indicates that providers may equate a positive MRSA nasal PCR with positive culture growth and highlights the need for education on the interpretation of positive tests.

Antimicrobial Stewardship Techniques for Critically Ill Patients with Pneumonia

Pneumonia is common in the intensive care unit (ICU), infecting 27% of all critically ill patients. Given the high prevalence of this disease state in the ICU, optimizing antimicrobial therapy while minimizing toxicities is of utmost importance. Inappropriate antimicrobial use can increase the risk of antimicrobial resistance, Clostridiodes difficile infection, allergic reaction, and other complications from antimicrobial use (e.g., QTc prolongation, thrombocytopenia). This review article aims to discuss methods to optimize antimicrobial treatment in patients with pneumonia, including the following: procalcitonin use, utilization of methicillin-resistant Staphylococcus aureus nares testing to determine need for vancomycin therapy, utilization of the Biofire^® FilmArray^® pneumonia polymerase chain reaction (PCR), and microbiology reporting techniques.

Should a MRSA Nasal Swab Guide Empiric Antibiotic Treatment?

MRSA Nasal Swab and Empiric Antibiotic TreatmentMRSA nasal screening has emerged as a potential antimicrobial stewardship tool to guide empiric use of anti-MRSA therapy. The authors address diagnostic considerations when performing MRSA nasal screening and clinical situations in which its results may be used to guide empiric antibiotic therapy in hospitalized patients.

Antimicrobial stewardship

PURPOSE OF REVIEW

The optimal use of antimicrobials is necessary to slow resistance development and improve patient outcomes. Antimicrobial stewardship (AMS) is a bundle of interventions aimed at promoting the responsible use of antiinfectives. The ICU is an important field of activity for AMS because of high rates of antimicrobial use, high prevalence of resistant pathogens and complex pharmacology. This review discusses aims and interventions of AMS with special emphasis on the ICU.

RECENT FINDINGS

AMS-interventions can improve the quality and quantity of antimicrobial prescribing in the ICU without compromising patient outcomes. The de-escalation of empiric therapy according to microbiology results and the limitation of treatment duration are important steps to reduce resistance pressure. Owing to the complex nature of critical illness, the pharmacological optimization of antimicrobial therapy is an important goal in the ICU. AMS-objectives and strategies are also applicable to patients with sepsis. This is reflected in the most recent guidelines by the Surviving Sepsis Campaign. AMS-interventions need to be adapted to their respective setting and be mindful of local prescribing cultures and prescribers' attitudes.

SUMMARY

AMS in the ICU is effective and safe. Intensivists should be actively involved in AMS-programs and propagate responsible use of antimicrobials.

Pharmacist-Driven Methicillin-Resistant S. aureus Polymerase Chain Reaction Testing for Pneumonia

BACKGROUND

Nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) can be detected using nasal swab polymerase chain reaction (PCR) assay and is associated with clinical MRSA infection. The MRSA nasal PCR has a rapid turnaround time and a negative predictive value for MRSA pneumonia of >98%; however, data are limited in critically ill patients.

OBJECTIVE

The purpose of this study is to determine the impact of a pharmacist-driven algorithm, utilizing MRSA PCR nasal screening on duration of anti-MRSA therapy in patients admitted to the intensive care unit (ICU) with suspected pneumonia.

METHODS

A single-center pre/post study was conducted in 4 ICUs at a large tertiary care community hospital. Adult patients admitted to the ICU initiated on vancomycin or linezolid for pneumonia managed using a pharmacist-driven MRSA PCR algorithm were included in the algorithm cohort. A historical cohort with standard management was matched 1:1 by age, type of pneumonia, and Acute Physiology and Chronic Health Evaluation II (APACHE II) score. The primary outcome was duration of anti-MRSA therapy. Secondary outcomes included MRSA rates, number of vancomycin levels, new onset of acute kidney injury (AKI), ICU length of stay (LOS), hospital LOS, and mortality.

RESULTS

Of the 245 patients screened, 50 patients met inclusion criteria for the algorithm cohort and were matched to 50 patients in the historical cohort. The duration of anti-MRSA therapy was significantly lower compared with the historical cohort (47 vs 95 hours; P < 0.001). Secondary outcomes were similar between groups for MRSA rates, new onset of AKI, LOS, and mortality. There were less vancomycin levels ordered in the algorithm cohort (2 vs 3, P = 0.026).

CONCLUSIONS

A pharmacist-driven MRSA PCR algorithm significantly reduced anti-MRSA duration of therapy in critically ill patients with pneumonia. Future studies should validate these results in critically ill populations and in settings where MRSA pneumonia is more prevalent.

Utility of Methicillin-Resistant Staphylococcus aureus Nares Screening in Hospitalized Children with Acute Infectious Disease Syndromes

Studies in adults support the use of a negative methicillin-resistant Staphylococcus aureus (MRSA) nares screening (MNS) to help limit empiric anti-MRSA antibiotic therapy. We aimed to evaluate the use of MNS for anti-MRSA antibiotic de-escalation in hospitalized children (<18 years). Records of patients admitted between 1 January 2015 and 31 December 2020 with a presumed infectious diagnosis who were started on anti-MRSA antibiotics, had a PCR-based MNS, and a clinical culture performed were retrospectively reviewed. A total of 95 children were included with a median age (range) of 2 (0–17) years. The top three diagnosis groups were skin and soft tissue infections (n = 38, 40%), toxin-mediated syndromes (n = 17, 17.9%), and osteoarticular infections (n = 14, 14.7%). Nasal MRSA colonization and growth of MRSA in clinical cultures was found in seven patients (7.4%) each. The specificity and the negative predictive value (NPV) of the MNS to predict a clinical MRSA infection were both 95.5%. About half (n = 55, 57.9%) had anti-MRSA antibiotics discontinued in-house. A quarter (n = 14, 25.5%) were de-escalated based on the negative MNS test alone, and another third (n = 21, 38.2%) after negative MNS test and negative culture results became available. A high NPV suggests that MNS may be useful for limiting unnecessary anti-MRSA therapy and thereby a useful antimicrobial stewardship tool for hospitalized children. Prospective studies are needed to further characterize the utility of MNS for specific infectious diagnoses.