A trial of discontinuation of empiric vancomycin therapy in patients with suspected methicillin-resistant Staphylococcus aureus health care-associated pneumonia

Using Methicillin-Resistant Staphylococcus aureus Nasal Screens to Rule Out Methicillin-Resistant S aureus Pneumonia in Surgical Intensive Care Units

INTRODUCTION

The methicillin-resistant Staphylococcus aureus (MRSA) polymerase chain reaction (PCR) has a high negative predictive value (NPV). We aimed to understand if there was a difference in the NPV of the MRSA screen in surgical intensive care units (ICUs) and to determine its role in antibiotic de-escalation.

METHODS

We performed a single-center, retrospective cohort study of adults with a positive respiratory culture and MRSA nasal PCR admitted to a surgical ICU from 2016 to 2019. Patients were stratified by surgical ICU: cardiothoracic/cardiovascular intensive care unit (CVICU) or transplant/acute care surgery intensive care unit (ACS-ICU). Our primary outcome was the NPV of MRSA screen. Secondary outcome was the duration of empiric MRSA-targeted therapy.

RESULTS

We analyzed 61 patients: 42.6% (n = 26) ACS-ICU and 57.4% (n = 35) CVICU. There were no differences in age, comorbidities, prior MRSA infection, recent antibiotic use, immunocompromised status, or renal replacement therapy. At pneumonia diagnosis, more patients in the ACS-ICU were hospitalized ≥5 d (65.4% versus 8.6%, P < 0.0001) and more patients in the CVICU were in septic shock (88.6% versus 34.5%, P < 0.0001) and thrombocytopenic (40% versus 11.5%, P = 0.02). NPV of the PCR was similar (ACS-ICU: 0.92 [0.75-0.98], CV-ICU 0.89 [0.73-0.96]). On multivariable linear regression, the CVICU was associated with longer empiric therapy (β 1.5, 95% CI 0.8-2.3, P < 0.0001), as was hospitalization for ≥5 d (β 0.73, 95% CI 0.06-1.39, P = 0.03).

CONCLUSIONS

The MRSA nasal PCR screen has a high NPV for ruling out MRSA pneumonia in critically ill surgical patients. However, patients in the CVICU and patients hospitalized ≥5 d had a longer time to de-escalation of MRSA-targeted therapy, potentially due to higher clinical risk profile.

Predictive Value of MRSA Nares Colonization in Diabetic Foot Infections: A Systematic Review and Bivariate Random Effects Meta-Analysis

The primary objective of this study was to assess the negative predictive value of methicillin-resistant Staphylococcus aureus (MRSA) nasal swabs in MRSA diabetic foot infections. MEDLINE and Cochrane Library were searched from inception to May 1, 2020. The following search string was used: (methicillin-resistant S. aureus OR MRSA) AND (nasal OR nares) AND (diabetic OR foot OR diabetic foot infections). All studies that contained data comparing MRSA nasal swab positivity to wound cultures from diabetic foot infections and met the inclusion criteria were included. Among the 86 relevant studies, 6 studies with 8706 diabetic patients were included. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline extension for Diagnostic Test Accuracy reviews was followed. The primary meta-analysis outcomes were the negative and positive predictive values of MRSA nasal swabs for MRSA diabetic foot infections. The pooled specificity and pooled sensitivity were determined by generating hierarchical summary receiver characteristic operating curves. In the bivariate meta-analysis, involving the 6 studies, pooled sensitivity and specificity was 41.7% (95% confidence interval = 32.9, 51) and 94.1% (95% confidence interval = 89.5, 96.8), respectively. In low-moderate MRSA prevalence levels (<15%), negative predictive value of MRSA nasal swab was >90% and positive predictive value was <55%. This meta-analysis suggests that in patients with diabetic foot infections, the nasal swab MRSA screen has a poor positive predictive value but an excellent negative predictive value in regions of low to moderate prevalence of MRSA diabetic foot infections.

Clinical utility of dual anterior nares and oropharynx MRSA screening polymerase chian reaction assay (PCR) for patients with suspected pneumonia

We reviewed the electronic health records of 1,419 inpatients with anterior nares (AN) and oropharynx (OP) MRSA PCR tests. Concordance was 96.5%. In discordant cases, AN negative-OP positive results increased detection of probable MRSA pneumonia by only 0.3%. A dual testing approach has limited utility in detecting MRSA pneumonia and increases resource utilization.

Efficacy and validity of guideline-concordant treatment according to the JRS guidelines for the managements of pneumonia in adults updated in 2017 for nursing and healthcare-associated pneumonia. A propensity-matching score analysis

INTRODUCTION

Patients with nursing and healthcare-associated pneumonia (NHCAP) commonly receive empiric antibiotic therapy according to the guideline's recommendation corresponding to the patient's deteriorated conditions. However, it is unclear whether guideline-concordant treatment (GCT) could be effective or not.

PATIENTS AND METHODS

To evaluate the efficacy and validity of GCT according to the current guideline for pneumonia, we conducted this retrospective study. NHCAP patients who were admitted to our institute between 2014 and 2017 were enrolled. Based on the initial antibiotic treatment, these patients were divided into two groups, the GCT group (n = 83) and the non-GCT group (n = 146). Propensity score matching (PSM) was used to balance the baseline characteristics and potential confounders between the two groups. After PSM, patients' characteristics, microbial profiles, and clinical outcomes were evaluated.

RESULTS

Both groups were well-balanced after PSM, and 78 patients were selected from each group. There were no differences in patients' characteristics or microbial profiles between the two groups. As for outcomes, there were no differences in 30-day, in-hospital mortality rate, duration of antibiotic treatment, or admission. The severity of pneumonia was more severe in patients with the GCT group than those with the non-GCT group. Anti-pseudomonal agents as initial treatment were more frequently seen in patients with the GCT group than those in the non-GCT group.

CONCLUSION

Unlike previous studies, GCT's recommendation for management of pneumonia by the JRS in 2017 would appear to be valid and does not increase the mortality rate.

Evaluation of MRSA surveillance nasal swabs for predicting MRSA infection in SICU patients

BACKGROUND

We aimed to examine the clinical value of serial MRSA surveillance cultures to rule out a MRSA diagnosis on subsequent cultures during a patient's surgical intensive care unit (SICU) admission.

MATERIAL AND METHODS

We performed a retrospective cohort study to evaluate patients who received a MRSA surveillance culture at admission to the SICU (n = 6,915) and collected and assessed all patient cultures for MRSA positivity during their admission. The primary objective was to evaluate the transition from a MRSA negative surveillance on admission to MRSA positive on any subsequent culture during a patient's SICU stay. Percent of MRSA positive cultures by type following MRSA negative surveillance cultures was further analyzed.

MEASUREMENTS AND MAIN RESULTS

6,303 patients received MRSA nasal surveillance cultures at admission with 21,597 clinical cultures and 7,269 MRSA surveillance cultures. Of the 6,163 patients with an initial negative, 53 patients (0.87%) transitioned to MRSA positive. Of the 139 patients with an initial positive, 30 (21.6%) had subsequent MRSA positive cultures. Individuals who had an initial MRSA surveillance positive status on admission predicted MRSA positivity rates for cultures in qualitative lower respiratory cultures (64.3% versus. 3.1%), superficial wound (60.0% versus 1.6%), deep wound (39.0% versus 0.8%), tissue culture (26.3% versus 0.6%), and body fluid (20.8% versus 0.7%) cultures when compared to MRSA negative patients on admission.

CONCLUSION

Following MRSA negative nasal surveillance cultures patients showed low likelihood of MRSA infection suggesting empiric anti-MRSA treatment is unnecessary for specific patient populations. SICU patient's MRSA status at admission should guide empiric anti-MRSA therapy.

Comparative incidence of acute kidney injury in patients on vancomycin therapy in combination with cefepime, piperacillin-tazobactam or meropenem

Recent studies have shown that the incidence of nephrotoxicity increases when vancomycin is combined with a beta-lactam antibiotic. The objective of this study was to compare the incidence of acute kidney injury (AKI) in adult patients who received vancomycin with either piperacillin-tazobactam (VPT), cefepime (VC), or meropenem (VM). This was a single center retrospective chart review. Patients were included if they were 18 years or older, received 48 hours of combination therapy and antibiotics were started within 24 hours of each other. Exclusion criteria were receiving more than one combination of antibiotics, serum creatinine > 1.2 mg/dL, AKI at the time of inclusion, or any form of renal replacement therapy. Two hundred patients met inclusion criteria. A total of 27 (13%) patients experienced AKI. The incidence of AKI was 21.6%, 9%, and 7.4% in the VPT, VC and VM groups, respectively. A patient who received VPT was 5 times more likely to develop AKI when compared to a patient who received VC (adjusted OR 5.09 95% CI (1.51-17.08), p = 0.008) and 7 times more likely to develop AKI when compared to VM (adjusted OR 7.03 95% CI (1.97-28.08), p = 0.002). This study found a statistically significant difference in the incidence of AKI in patient receiving VPT when compared to VC or VM. This finding supports the need for careful monitoring of renal function in patients receiving VPT therapy and routine evaluation for de-escalation of antimicrobial therapy.

Discontinuation Patterns and Cost Avoidance of a Pharmacist-Driven Methicillin-Resistant Staphylococcus aureus Nasal Polymerase Chain Reaction Testing Protocol for De-escalation of Empiric Vancomycin for Suspected Pneumonia

A pharmacist-driven methicillin-resistant Staphylococcus aureus (MRSA) nasal polymerase chain reaction (PCR)-based testing protocol with a 70% acceptance rate for vancomycin discontinuation within 24 hours of negative results significantly reduced unnecessary vancomycin use with an estimated cost avoidance of $40 per vancomycin course. We found high concordance (141 of 147, 96%) of culture-based versus PCR-based MRSA nasal screening.

Culture-negative sepsis

PURPOSE OF REVIEW

The traditional approach to sepsis treatment utilizes broad-spectrum antibiotics. Unfortunately, a significant proportion of infected patients have 'culture-negative' sepsis despite appropriate microbiologic assessment.

RECENT FINDINGS

There has been increased interest in the past decade on the treatment of culture-negative sepsis. Outcome data comparing culture-negative sepsis with culture-positive sepsis are mixed and it is unclear if culture-negative sepsis is a distinct entity. Recent recommendations promoting antibiotic de-escalation in culture-negative sepsis can be difficult to implement. A variety of strategies have been suggested for limiting antibiotic courses among patients with negative cultures, including limiting antibiotic durations, use of antibiotic stewardship programs, early consideration of narrow antibiotics, rapid diagnostic technology, and eliminating anti-MRSA therapy based on surveillance swabs.

SUMMARY

Owing to the difficulty inherent in studying the lack of positive data, and to the uncertainty surrounding diagnosis in patients with culture-negative sepsis, prospective data to guide antibiotic choices are lacking. However, antibiotic de-escalation in culture-negative sepsis is both recommended and feasible in patients showing clinical signs of improvement. Increased use of rapid diagnostics, careful consideration of antibiotic necessity, and antibiotic stewardship programs may result in less antibiotic days and better outcomes.

The Clinical Utility of Methicillin-Resistant Staphylococcus aureus (MRSA) Nasal Screening to Rule Out MRSA Pneumonia: A Diagnostic Meta-analysis With Antimicrobial Stewardship Implications

Background

Recent literature has highlighted methicillin-resistant Staphylococcus aureus (MRSA) nasal screening as a possible antimicrobial stewardship program tool for avoiding unnecessary empiric MRSA therapy for pneumonia, yet current guidelines recommend MRSA therapy based on risk factors. The objective of this meta-analysis was to evaluate the diagnostic value of MRSA nasal screening in MRSA pneumonia.

Methods

PubMed and EMBASE were searched from inception to November 2016 for English studies evaluating MRSA nasal screening and development of MRSA pneumonia. Data analysis was performed using a bivariate random-effects model to estimate pooled sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

Results

Twenty-two studies, comprising 5163 patients, met our inclusion criteria. The pooled sensitivity and specificity of MRSA nares screen for all MRSA pneumonia types were 70.9% and 90.3%, respectively. With a 10% prevalence of potential MRSA pneumonia, the calculated PPV was 44.8%, and the NPV was 96.5%. The pooled sensitivity and specificity for MRSA community-acquired pneumonia (CAP) and healthcare-associated pneumonia (HCAP) were 85% and 92.1%, respectively. For CAP and HCAP both the PPV and NPV increased, to 56.8% and 98.1%, respectively. In comparison, for MRSA ventilated-associated pneumonia, the sensitivity, specificity, PPV, and NPV were 40.3%, 93.7%, 35.7%, and 94.8%, respectively.

Conclusion

Nares screening for MRSA had a high specificity and NPV for ruling out MRSA pneumonia, particularly in cases of CAP/HCAP. Based on the NPV, MRSA nares screening is a valuable tool for AMS to streamline empiric antibiotic therapy, especially among patients with pneumonia who are not colonized with MRSA.

Health Care-Associated Pneumonia: Is It Still a Useful Concept?

"Health care-associated pneumonia (HCAP) was introduced into guidelines because of concerns about the increasing prevalence of drug-resistant pathogens (DRPs) not covered by standard empirical therapy. We now know that DRPs are very localized phenomena with low rates in most sites. Although HCAP risk factors are associated with a higher mortality, this is driven by comorbidities rather than the pathogens. Empirical coverage of DRPs has generally not resulted in better patient outcomes. A far more nuanced approach must be taken for patients with risk factors for DRPs taking into account the local cause and severity of disease.

Systematic Review of the Clinical Utility of Methicillin-Resistant Staphylococcus aureus (MRSA) Nasal Screening for MRSA Pneumonia

Objective: To describe the diagnostic performance characteristics of methicillin-resistant Staphylococcus aureus (MRSA) nasal screening for patients with pneumonia. Data Sources: PubMed and Scopus were searched from 1 January 1990 to 12 December 2018 using terms methicillin-resistant Staphylococcus aureus AND (screening OR active surveillance OR surveillance culture OR targeted surveillance OR chromogenic OR PCR OR polymerase chain reaction OR rapid test) AND (nares OR nasal) AND (pneumonia OR respiratory). Study Selection and Data Extraction: Relevant studies in humans and English were considered. Data Synthesis: In all, 19 studies, including 21 790 patients, were included. Nasal screening for MRSA had a high negative predictive value (NPV; 76% to 99.4% for relevant studies) across all types of pneumonia. Time from nasal screening to culture varied across studies. Relevance to Patient Care and Clinical Practice: MRSA nasal screening has a high NPV for MRSA involvement in pneumonia. Utilizing this test for antimicrobial stewardship program (ASP) purposes can provide a valuable tool for reducing unwarranted anti-MRSA agents and may provide additional cost benefits. A cutoff of 7 days between nasal swab and culture or infection onset seems most appropriate for use of this test for anti-MRSA agent de-escalation for ASP purposes. Conclusions: Consideration for the inclusion of the utility of MRSA nasal screening in MRSA pneumonia should be made for future pneumonia and ASP guidelines. Additional studies are warranted to fully evaluate specific pneumonia classifications, culture types, culture timing, and clinical outcomes associated with the use of this test in patients with pneumonia.

Clinical Utility of Methicillin-Resistant Staphylococcus aureus Nasal Screening for Antimicrobial Stewardship: A Review of Current Literature

Significant clinical and financial consequences are associated with both inadequate and unnecessary exposure to broad-spectrum antibiotics. As such, antimicrobial stewardship programs seek objective, reliable, and cost-effective tests to identify patients at highest or lowest risk for drug-resistant organisms to guide empirical antimicrobial selection. Use of methicillin-resistant Staphylococcus aureus (MRSA) nasal screening to rule out MRSA in lower respiratory tract infections has led to significant reductions in duration of vancomycin therapy. The clinical utility of MRSA nasal screening in other types of infection remains less clear. This review describes the performance of MRSA nasal screening in predicting MRSA infection, highlights practical considerations for use of MRSA nasal screening, and provides guidance for incorporating MRSA nasal screening into clinical practice. With a high negative predictive value when the prevalence of MRSA is low, MRSA nasal screening is a valuable antimicrobial stewardship tool with potential applications beyond lower respiratory tract infections. In appropriately selected patients, negative MRSA nasal screening can prevent initiation or guide discontinuation of anti-MRSA therapy. Antimicrobial stewardship programs should develop institutional guidelines to promote proper use of MRSA nasal screening. Pharmacists are well positioned to assist with education, interpretation, and application of MRSA nasal screening results.

Antibiotic de-escalation in patients with pneumonia in the intensive care unit: A systematic review and meta-analysis

OBJECTIVES OF THE REVIEW

Antibiotic de-escalation is part of an antibiotic stewardship strategy to achieve adequate therapy for infections while avoiding the prolonged use of broad-spectrum antibiotics. However, there is a paucity of clinical evidence on the clinical impact of this strategy in pneumonia patients in the intensive care unit (ICU). This review aimed to evaluate the impact of antibiotic de-escalation therapy for adult patients diagnosed with pneumonia in the ICU.

METHODS USED TO CONDUCT THE REVIEW

This review was conducted in accordance with the Meta-analysis of Observational Studies in Epidemiology (MOOSE) recommendation. Electronic databases including MEDLINE, CINAHL, PubMed, Embase, Cochrane Databases and Cochrane Central Register of Controlled Trials were searched up to March 2017 for relevant trials. The methodological quality of included trials was assessed by using a modified version of the Newcastle-Ottawa Quality Assessment Scale for Case-Control and Cohort Studies. A meta-analysis was conducted using the random-effect model to combine the rate of mortality and length of stay outcomes.

FINDINGS OF THE REVIEW

Nine observational trials involving 2128 patients were considered eligible for inclusion. Although based on low quality evidence, there was a statistically significant difference in favour of the impact of de-escalation on hospital stay but not mortality (MD -5.96 days; 95% CI -8.39 to -3.52).

INTERPRETATIONS AND IMPLICATIONS OF THE FINDINGS

This review highlights the need for more rigorous studies to be carried out before a firm conclusion on the benefit of de-escalation therapy is supported.

The Role of Negative Methicillin-Resistant Staphylococcus aureus Nasal Surveillance Swabs in Predicting the Need for Empiric Vancomycin Therapy in Intensive Care Unit Patients

OBJECTIVES The role of methicillin-resistant Staphylococcus aureus (MRSA) nasal surveillance swabs (nasal swabs) in guiding decisions about prescribing vancomycin is unclear. We aimed to determine the likelihood that patients with negative MRSA nasal swabs develop subsequent MRSA infections; to assess avoidable vancomycin days for patients with negative nasal swabs; and to identify risk factors for having a negative nasal swab and developing a MRSA infection during the intensive care unit (ICU) stay. METHODS This retrospective cohort study was conducted in 6 ICUs at a tertiary-care hospital from December 2013 through June 2015. The negative predictive value (NPV), defined as the ability of a negative nasal swab to predict no subsequent MRSA infection, was calculated. Days of vancomycin continued or restarted after 3 days from the collection time of the first negative nasal swab were determined. A matched case-control study identified risk factors for having a negative nasal swab and developing MRSA infection. RESULTS Of 11,441 patients with MRSA-negative nasal swabs, the rate of subsequent MRSA infection was 0.22%. A negative nasal swab had a NPV of 99.4% (95% confidence interval [CI], 99.1%-99.6%). Vancomycin was continued or started after nasal swab results were available in 1,431 patients, translating to 7,364 vancomycin days. No risk factors associated with MRSA infection were identified. CONCLUSIONS In our hospital with a low prevalence of MRSA transmission, a negative MRSA nasal swab was helpful in identifying patients with low risk of MRSA infection in whom empiric vancomycin therapy could be stopped and in whom the subsequent initiation of vancomycin therapy during an ICU admission could be avoided. Infect Control Hosp Epidemiol 2018;39:290-296.

Multifunctional Biochar for Highly Efficient Capture, Identification, and Removal of Toxic Metals and Superbugs from Water Samples

According to the World Health Organization, more than two billion people in our world use drinking water sources which are not free from pathogens and heavy metal contamination. Unsafe drinking water is responsible for the death of several millions in the 21st century. To find facile and cost-effective routes for developing multifunctional materials, which has the capability to resolve many of the challenges associated with drinking water problem, here, we report the novel design of multifunctional fluorescence-magnetic biochar with the capability for highly efficient separation, identification, and removal of pathogenic superbugs and toxic metals from environmental water samples. Details of synthesis and characterization of multifunctional biochar that exhibits very good magnetic properties and emits bright blue light owing to the quantum confinement effect are reported. In our design, biochar, a carbon-rich low-cost byproduct of naturally abundant biomass, which exhibits heterogeneous surface chemistry and strong binding affinity via oxygen-containing group on the surface, has been used to capture pathogens and toxic metals. Biochar dots (BCDs) of an average of 4 nm size with very bright photoluminescence have been developed for the identification of pathogens and toxic metals. In the current design, magnetic nanoparticles have been incorporated with BCDs which allow pathogens and toxic metals to be completely removed from water after separation by an external magnetic field. Reported results show that owing to the formation of strong complex between multifunctional biochar and cobalt(II), multifunctional biochar can be used for the selective capture and removal of Co(II) from environmental samples. Experimental data demonstrate that multifunctional biochar can be used for the highly efficient removal of methicillin-resistant Staphylococcus aureus (MRSA) from environmental samples. Reported results also show that melittin, an antimicrobial peptide-attached multifunctional biochar, has the capability to completely disinfect MRSA superbugs after magnetic separation. A possible mechanism for the selective separation of Co(II), as well as separation and killing of MRSA, has been discussed.

Nasal-Swab Results for Methicillin-Resistant Staphylococcus aureus and Associated Infections

BACKGROUND

Nasal-swab screening for methicillin-resistant Staphylococcus aureus (MRSA) has a quicker turnaround time than other bacterial culture methods, with results available within 24 h. Although MRSA nasal-swab screening is not intended to guide antimicrobial therapy, this method may give clinicians additional information for earlier tailoring of empiric antimicrobial agents.

OBJECTIVE

To describe the diagnostic characteristics of nasal-swab screening in predicting MRSA infections in hospitalized patients receiving empiric treatment with IV vancomycin.

METHODS

A retrospective observational chart review was conducted for newly admitted adult patients of the Peter Lougheed Centre in Calgary, Alberta, who were treated empirically with IV vancomycin from January to October 2015 and who underwent nasal-swab screening for MRSA. The diagnostic characteristics of nasal-swab screening were calculated in relation to corresponding culture results for samples collected on admission.

RESULTS

For the 273 patients included in this study, nasal-swab screening for MRSA showed the following diagnostic characteristics in relation to bacterial culture results: sensitivity 58.3% (95% confidence interval [CI] 28.6%-83.5%), specificity 93.9% (95% CI 90.0%-96.3%), positive predictive value 30.4% (95% CI 14.1%-53.0%), negative predictive value 98.0% (95% CI 95.1%-99.3%), positive likelihood ratio 9.5 (95% CI 4.9-18.7), and negative likelihood ratio 0.4 (95% CI 0.2-0.9).

CONCLUSIONS

Given the high specificity of this rapid method, clinicians should ensure that patients who are receiving empiric treatment for MRSA infection and who have a positive result on nasal-swab screening continue to receive MRSA coverage until culture results are available. In addition, the high negative predictive value and positive likelihood ratio for nasal-swab screening in a low-prevalence setting suggest that a negative result significantly reduces the probability of MRSA infection. Although nasal-swab screening for MRSA is currently used for determining isolation precautions, this method also had utility in helping clinicians to predict the probability of MRSA infection and in guiding decisions about antimicrobial therapy.

Frequency of empiric antibiotic de-escalation in an acute care hospital with an established Antimicrobial Stewardship Program

BACKGROUND

Expanding antimicrobial resistance patterns in the face of stagnant growth in novel antibiotic production underscores the importance of antibiotic stewardship in which de-escalation remains an integral component. We measured the frequency of antibiotic de-escalation in a tertiary care medical center with an established antimicrobial stewardship program to provide a plausible benchmark for de-escalation.

METHODS

A retrospective, observational study was performed by review of randomly selected electronic medical records of 240 patients who received simultaneous piperacillin/tazobactam and vancomycin from January to December 2011 at an 885-bed tertiary care medical center. Patient characteristics including antibiotic regimen, duration and indication, culture results, length of stay, and hospital mortality were evaluated. Antibiotic de-escalation was defined as the use of narrower spectrum antibiotics or the discontinuation of antibiotics after initiation of piperacillin/tazobactam and vancomycin therapy. Subjects dying within 72 h of antibiotic initiation were considered not de-escalated for subsequent analysis and were subtracted from the study population in determining a modified mortality rate.

RESULTS

The most commonly documented indications for piperacillin/tazobactam and vancomycin therapy were pneumonia and sepsis. Of the 240 patients studied, 151 (63%) had their antibiotic regimens de-escalated by 72 h. The proportion of patients de-escalated by 96 h with positive vs. negative cultures was similar, 71 and 72%, respectively. Median length of stay was 4 days shorter in de-escalated patients, and the difference in adjusted mortality was not significant (p = 0.82).

CONCLUSIONS

The empiric antibiotic regimens of approximately two-thirds of patients were de-escalated by 72 h in an institution with a well-established antimicrobial stewardship program. While this study provides one plausible benchmark for antibiotic de-escalation, further studies, including evaluations of antibiotic appropriateness and patient outcomes, are needed to inform decisions on potential benchmarks for antibiotic de-escalation.

Using MRSA Screening Tests To Predict Methicillin Resistance in Staphylococcus aureus Bacteremia

Bloodstream infections with Staphylococcus aureus are clinically significant and are often treated with empirical methicillin resistance (MRSA, methicillin-resistant S. aureus) coverage. However, vancomycin has associated harms. We hypothesized that MRSA screening correlated with resistance in S. aureus bacteremia and could help determine the requirement for empirical vancomycin therapy. We reviewed consecutive S. aureus bacteremias over a 5-year period at two tertiary care hospitals. MRSA colonization was evaluated in three ways: as tested within 30 days of bacteremia (30-day criterion), as tested within 30 days but accounting for any prior positive results (ever-positive criterion), or as tested in known-positive patients, with patients with unknown MRSA status being labeled negative (known-positive criterion). There were 409 S. aureus bacteremias: 302 (73.8%) methicillin-susceptible S. aureus (MSSA) and 107 (26.2%) MRSA bacteremias. In the 167 patients with MSSA bacteremias, 7.2% had a positive MRSA test within 30 days. Of 107 patients with MRSA bacteremia, 68 were tested within 30 days (54 positive; 79.8%), and another 21 (19.6%) were previously positive. The 30-day criterion provided negative predictive values (NPV) exceeding 90% and 95% if the prevalence of MRSA in S. aureus bacteremia was less than 33.4% and 19.2%, respectively. The same NPVs were predicted at MRSA proportions below 39.7% and 23.8%, respectively, for the ever-positive criterion and 34.4% and 19.9%, respectively, for the known-positive criterion. In MRSA-colonized patients, positive predictive values exceeded 50% at low prevalence. MRSA screening could help avoid empirical vancomycin therapy and its complications in stable patients and settings with low-to-moderate proportions of MRSA bacteremia.

Derivation and Multicenter Validation of the Drug Resistance in Pneumonia Clinical Prediction Score

The health care-associated pneumonia (HCAP) criteria have a limited ability to predict pneumonia caused by drug-resistant bacteria and favor the overutilization of broad-spectrum antibiotics. We aimed to derive and validate a clinical prediction score with an improved ability to predict the risk of pneumonia due to drug-resistant pathogens compared to that of HCAP criteria. A derivation cohort of 200 microbiologically confirmed pneumonia cases in 2011 and 2012 was identified retrospectively. Risk factors for pneumonia due to drug-resistant pathogens were evaluated by logistic regression, and a novel prediction score (the drug resistance in pneumonia [DRIP] score) was derived. The score was then validated in a prospective, observational cohort of 200 microbiologically confirmed cases of pneumonia at four U.S. centers in 2013 and 2014. The DRIP score (area under the receiver operator curve [AUROC], 0.88 [95% confidence interval {CI}, 0.82 to 0.93]) performed significantly better (P = 0.02) than the HCAP criteria (AUROC, 0.72 [95% CI, 0.64 to 0.79]). At a threshold of ≥4 points, the DRIP score demonstrated a sensitivity of 0.82 (95% CI, 0.67 to 0.88), a specificity of 0.81 (95% CI, 0.73 to 0.87), a positive predictive value (PPV) of 0.68 (95% CI, 0.56 to 0.78), and a negative predictive value (NPV) of 0.90 (95% CI, 0.81 to 0.93). By comparison, the performance of HCAP criteria was less favorable: sensitivity was 0.79 (95% CI, 0.67 to 0.88), specificity was 0.65 (95% CI, 0.56 to 0.73), PPV was 0.53 (95% CI, 0.42 to 0.63), and NPV was 0.86 (95% CI, 0.77 to 0.92). The overall accuracy of the HCAP criteria was 69.5% (95% CI, 62.5 to 75.7%), whereas that of the DRIP score was 81.5% (95% CI, 74.2 to 85.6%) (P = 0.005). Unnecessary extended-spectrum antibiotics were recommended 46% less frequently by applying the DRIP score (25/200, 12.5%) than by use of HCAP criteria (47/200, 23.5%) (P = 0.004), without increasing the rate at which inadequate treatment recommendations were made. The DRIP score was more predictive of the risk of pneumonia due to drug-resistant pathogens than HCAP criteria and may have the potential to decrease antibiotic overutilization in patients with pneumonia. Validation in larger cohorts of patients with pneumonia due to all causes is necessary.

Using active methicillin-resistant Staphylococcus aureus surveillance nasal swabs to predict clinical respiratory culture results

PURPOSE

Results of a study to determine the utility of methicillin-resistant Staphylococcus aureus (MRSA) active surveillance via nasal-swab screening in predicting the results of clinical respiratory cultures are reported.

METHODS

A retrospective chart review-based descriptive analysis was conducted at a Veterans Affairs (VA) medical center. VA databases were used to identify adult patients admitted to the facility over a one-year period who underwent both respiratory culture testing and active MRSA surveillance nasal-swab screening during the hospitalization; only data on patients who had a MRSA surveillance swab within 48 hours before or after respiratory culture testing were included in the analysis. The sensitivity, specificity, and positive and negative predictive values of the MRSA screening method were calculated.

RESULTS

Data on a total of 297 respiratory cultures and corresponding nasal-swab results were reviewed. The positive predictive value of the nasal-swab method of MRSA surveillance screening was calculated as 37.5% (95% confidence interval [CI], 21.1-56.3%); the negative predictive value was 99.3% (95% CI, 97.3-99.9%). MRSA screening by nasal swab had a calculated specificity of 92.9% (95% CI, 89.3-95.6%) and sensitivity of 87.5% (95% CI, 57.2-98.2%). Using Fisher's exact test, it was determined that there was a significant association between swab and culture results (p < 0.001).

CONCLUSION

This analysis demonstrated a notable association between negative results of nasal-swab screening for MRSA and an absence of MRSA growth on respiratory clinical cultures at the study site, suggesting that airway swab screening can be a useful tool for streamlining antimicrobial therapy.

Antimicrobial de-escalation of treatment for healthcare-associated pneumonia within the Veterans Healthcare Administration

OBJECTIVES

The objective of this study was to measure quantitatively antimicrobial de-escalation utilizing electronic medication administration data based on the spectrum of activity for antimicrobial therapy (i.e. spectrum score) to identify variables associated with de-escalation in a nationwide healthcare system.

METHODS

A retrospective cohort study of patients hospitalized for healthcare-associated pneumonia was conducted in Veterans Affairs Medical Centers (n = 119). Patients hospitalized for healthcare-associated pneumonia on acute-care wards between 5 and 14 days who received antimicrobials for ≥ 3 days during calendar years 2008-11 were evaluated. The spectrum score method was applied at the patient level to measure de-escalation on day 4 of hospitalization. De-escalation was expressed in aggregate and facility-level proportions. Logistic regression was used to assess variables associated with de-escalation. ORs with 95% CIs were reported.

RESULTS

Among 9319 patients, the de-escalation proportion was 28.3% (95% CI 27.4-29.2), which varied 6-fold across facilities [median (IQR) facility-level de-escalation proportion 29.1% (95% CI 21.7-35.6)]. Variables associated with de-escalation included initial broad-spectrum therapy (OR 1.5, 95% CI 1.4-1.5 for each 10% increase in spectrum), collection of respiratory tract cultures (OR 1.1, 95% CI 1.0-1.2) and care in higher complexity facilities (OR 1.3, 95% CI 1.1-1.6). Respiratory tract cultures were collected from 35.3% (95% CI 32.7-37.7) of patients.

CONCLUSIONS

De-escalation of antimicrobial therapy was limited and varied substantially across facilities. De-escalation was associated with respiratory tract culture collection and treatment in a high complexity-level facility.

Antibiotic de-escalation in the ICU: how is it best done?

PURPOSE OF REVIEW

An antimicrobial policy consisting of the initial use of wide-spectrum antimicrobials followed by a reassessment of treatment when culture results are available is termed de-escalation therapy. Our aim is to examine the safety and feasibility of antibiotic de-escalation in critically ill patients providing practical tips about how to accomplish this strategy in the critical care setting.

RECENT FINDINGS

Numerous studies have assessed the rates of de-escalation therapy (range from 10 to 60%) in patients with severe sepsis or ventilator-associated pneumonia as well as the factors associated with de-escalation. De-escalation generally refers to a reduction in the spectrum of administered antibiotics through the discontinuation of antibiotics or switching to an agent with a narrower spectrum. Diverse studies have identified the adequacy of initial therapy as a factor independently associated with de-escalation. Negative impact on different outcome measures has not been reported in the observational studies. Two randomized clinical trials have evaluated this strategy in patients with ventilator-associated pneumonia or severe sepsis. These trials alert us about the possibility that this strategy may be linked to a higher rate of reinfections but without an impact on mortality.

SUMMARY

Antibiotic de-escalation is a well tolerated management strategy in critically ill patients but unfortunately is not widely adopted.

Rapid automated microscopy for microbiological surveillance of ventilator-associated pneumonia

RATIONALE

Diagnosis of ventilator-associated pneumonia (VAP) is imprecise.

OBJECTIVES

To (1) determine whether alternate-day surveillance mini-bronchoalveolar lavage (mini-BAL) in ventilated adults could reduce time to initiation of targeted treatment and (2) evaluate the potential for automated microscopy to reduce analysis time.

METHODS

Adult intensive care unit patients who were anticipated to require ventilation for at least a further 48 hours were included. Mini-BALs were processed for identification, quantitation, and antibiotic susceptibility, using (1) clinical culture (50 ± 7 h) and (2) automated microscopy (∼5 h plus offline analysis).

MEASUREMENTS AND MAIN RESULTS

Seventy-seven mini-BALs were performed in 33 patients. One patient (3%) was clinically diagnosed with VAP. Of 73 paired samples, culture identified 7 containing pneumonia panel bacteria (>10(4) colony-forming units/ml) from five patients (15%) (4 Staphylococcus aureus [3 methicillin-resistant S. aureus], 2 Stenotrophomonas maltophilia, 1 Klebsiella pneumoniae) and resulted in antimicrobial changes/additions to two of five (40%) of those patients. Microscopy identified 7 of 7 microbiologically positive organisms and 64 of 66 negative samples compared with culture. Antimicrobial responses were concordant in four of five comparisons. Antimicrobial changes/additions would have occurred in three of seven microscopy-positive patients (43%) had those results been clinically available in 5 hours, including one patient diagnosed later with VAP despite negative mini-BAL cultures.

CONCLUSIONS

Microbiological surveillance detected infection in patients at risk for VAP independent of clinical signs, resulting in changes to antimicrobial therapy. Automated microscopy was 100% sensitive and 97% specific for high-risk pneumonia organisms compared with clinical culturing. Rapid microscopy-based surveillance may be informative for treatment and antimicrobial stewardship in patients at risk for VAP.

Inappropriate continued empirical vancomycin use in a hospital with a high prevalence of methicillin-resistant Staphylococcus aureus

Vancomycin is frequently inappropriately prescribed, especially as empirical treatment. The aim of this study was to evaluate (i) the amount of inappropriate continued empirical vancomycin use as a proportion of total vancomycin use and (ii) the risk factors associated with inappropriate continued empirical vancomycin use. We reviewed the medical records of adult patients who had been prescribed at least one dose of parenterally administered vancomycin between January and June 2012, in a single tertiary care hospital. When empirically prescribed vancomycin treatment was continued after 96 h without documentation of beta-lactam-resistant Gram-positive microorganisms in clinical specimens with significance, the continuation was considered inappropriate, and the amount used thereafter was considered inappropriately used. We identified risk factors associated with inappropriate continued empirical vancomycin use by multiple logistic regression. During the study period, the amount of parenterally administered vancomycin prescribed was 34.2 defined daily doses (DDDs)/1,000 patient-days (1,084 prescriptions for 971 patients). The amount of inappropriate continued empirical vancomycin use was 8.5 DDDs/1,000 patient-days, which represented 24.9% of the total parenterally administered vancomycin used (8.5/34.2 DDDs/1,000 patient-days). By multivariate analyses, inappropriate continued empirical vancomycin use was independently associated with the absence of any documented etiological organism (adjusted odds ratio [aOR], 1.60 [95% confidence interval {CI}, 1.06 to 2.41]) and suspected central nervous system (CNS) infections (aHR, 2.33 [95% CI, 1.20 to 4.50]). Higher Charlson's comorbidity index scores were inversely associated with inappropriate continued empirical vancomycin use (aHR, 0.90 [95% CI, 0.85 to 0.97]). Inappropriate continued empirical vancomycin use represented 24.9% of the total amount of vancomycin prescribed, which indicates room for improvement.

Guía de consenso para el abordaje de la neumonía adquirida en la comunidad en el paciente anciano

La incidencia de la neumonía adquirida en la comunidad se incrementa con la edad y se asocia a una elevada morbimortalidad debido a los cambios fisiológicos asociados al envejecimiento y a una mayor presencia de enfermedades crónicas. Debido a la importancia que tiene desde un punto de epidemiológico y pronóstico, y a la enorme heterogeneidad descrita en el manejo clínico, creemos que existía la necesidad de realizar un documento de consenso específico para este perfil de paciente. El propósito de este fue realizar una revisión de las evidencias en relación con los factores de riesgo para la etiología, la presentación clínica, el manejo y el tratamiento de la neumonía adquirida en la comunidad en los ancianos con el fin de elaborar una serie de recomendaciones específicas basadas en el análisis crítico de la literatura. Este documento es fruto de la colaboración de diferentes especialistas en representación de la Sociedad Española de Medicina de Urgencias y Emergencias (SEMES), Sociedad Española de Geriatría y Gerontología (SEGG), Sociedad Española de Quimioterapia (SEQ), Sociedad Española de Medicina Interna (SEMI), Sociedad Española de Neumología y Cirugía Torácica (SEPAR), Sociedad Española de Hospitalización a Domicilio (SEHAD) y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica (SEIMC).

Nasal screening is useful in excluding methicillin-resistant Staphylococcus aureus in ventilator-associated pneumonia

Methicillin-resistant Staphylococcus aureus screening performed for infection control purposes may be useful in guiding decisions regarding the use of broad-spectrum antibiotics in the intensive care unit. A cohort study of adults with ventilator-associated pneumonia (VAP) found that admission MRSA nasal swabs had a negative predictive value of 94% for later MRSA VAP.

Does universal active MRSA surveillance influence anti-MRSA antibiotic use? A retrospective analysis of the treatment of patients admitted with suspicion of infection at Veterans Affairs Medical Centers between 2005 and 2010

OBJECTIVES

After the implementation of an active surveillance programme for MRSA in US Veterans Affairs (VA) Medical Centers, there was an increase in vancomycin use. We investigated whether positive MRSA admission surveillance tests were associated with MRSA-positive clinical admission cultures and whether the availability of surveillance tests influenced prescribers' ability to match initial anti-MRSA antibiotic use with anticipated MRSA results from clinical admission cultures.

METHODS

Analyses were based on barcode medication administration data, microbiology data and laboratory data from 129 hospitals between January 2005 and September 2010. Hospitalized patient admissions were included if clinical cultures were obtained and antibiotics started within 2 days of admission. Mixed-effects logistic regression was used to examine associations between positive MRSA admission cultures and (i) admission MRSA surveillance test results and (ii) initial anti-MRSA therapy.

RESULTS

Among 569,815 included admissions, positive MRSA surveillance tests were strong predictors of MRSA-positive admission cultures (OR 8.5; 95% CI 8.2-8.8). The negative predictive value of MRSA surveillance tests was 97.6% (95% CI 97.5%-97.6%). The diagnostic OR between initial anti-MRSA antibiotics and MRSA-positive admission cultures was 3.2 (95% CI 3.1-3.4) for patients without surveillance tests and was not significantly different for admissions with surveillance tests.

CONCLUSIONS

The availability of nasal MRSA surveillance tests in VA hospitals did not seem to improve the ability of prescribers to predict the necessity of initial anti-MRSA treatment despite the high negative predictive value of MRSA surveillance tests. Prospective trials are needed to establish the safety and effectiveness of using MRSA surveillance tests to guide antibiotic therapy.

Active surveillance of the trachea or throat for MRSA is more sensitive than nasal surveillance and a better predictor of MRSA infections among patients in intensive care

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common causes of infection in the intensive care unit (ICU). Although surveillance culture for MRSA is recommended for ICU patients, no comparative study investigating the optimal sites and frequency of culture has been performed in this population.

METHODS

A prospective observational cohort study was performed in an 18-bed emergency intensive care unit (EICU) in a tertiary teaching hospital. A total of 282 patients were included. Samples for MRSA detection were obtained at the time of admission, 48 h after admission, and then weekly thereafter. All subjects were routinely monitored for the development of MRSA infection during their stay in the ICU.

RESULTS

MRSA colonization was detected in 129 (46%) patients over the course of the study. The sensitivity of MRSA surveillance culture was significantly higher in throat or tracheal aspirates (82%; 106/129) than in anterior nares (47%; 61/129) (P<0.001). The sensitivity of MRSA surveillance culture for subsequent MRSA infection and MRSA pneumonia was also higher in the throat/trachea (69 and 93%, respectively) than in the anterior nares (48 and 50%, respectively). The area under the curve for subsequent MRSA infection was higher in trachea/throat (0.675) than in the anterior nares (0.648); however, this difference was not significant (P>0.05). The area under the curve for MRSA pneumonia was significantly higher in trachea/throat (0.791; 95% CI, 0.739-0.837) than anterior nares (0.649; 95% CI, 0.590-0.705) (P = 0.044).

CONCLUSION

MRSA colonization was more common in the trachea/throat than in the anterior nares in ICU patients. Cultures from throat or tracheal aspirates were more sensitive and predictive of subsequent MRSA pneumonia than cultures from the anterior nares in this population.

Antimicrobial Stewardship Programs: Appropriate Measures and Metrics to Study their Impact

Antimicrobial stewardship is a new field that struggles to find the right balance between meaningful and useful metrics to study the impact of antimicrobial stewardship programs (ASPs). ASP metrics primarily measure antimicrobial use, although microbiological resistance and clinical outcomes are also important measures of the impact an ASP has on a hospital and its patient population. Antimicrobial measures looking at consumption are the most commonly used measures, and are focused on defined daily doses, days of therapy, and costs, usually standardized per 1,000 patient-days. Each measure provides slightly different information, with their own upsides and downfalls. Point prevalence measurement of antimicrobial use is an increasingly used approach to understanding consumption that does not entirely rely on sophisticated electronic information systems, and is also replicable. Appropriateness measures hold appeal and promise, but have not been developed to the degree that makes them useful and widely applicable. The primary reason why antimicrobial stewardship is necessary is the growth of antimicrobial resistance. Accordingly, antimicrobial resistance is an important metric of the impact of an ASP. The most common approach to measuring resistance for ASP purposes is to report rates of common or important community- or nosocomial-acquired antimicrobial-resistant organisms, such as methicillin-resistant Staphylococcus aureus and Clostridium difficile. Such an approach is dependent on detection methods, community rates of resistance, and co-interventions, and therefore may not be the most accurate or reflective measure of antimicrobial stewardship interventions. Development of an index to reflect the net burden of resistance holds theoretical promise, but has yet to be realized. Finally, programs must consider patient outcome measures. Mortality is the most objective and reliable method, but has several drawbacks. Disease- or organism-specific mortality, or cure, are increasingly used metrics.

Predictive value of methicillin-resistant Staphylococcus aureus (MRSA) nasal swab PCR assay for MRSA pneumonia

Pneumonia due to methicillin-resistant Staphylococcus aureus (MRSA) is associated with poor outcomes and frequently merits empirical antibiotic consideration despite its relatively low incidence. Nasal colonization with MRSA is associated with clinical MRSA infection and can be reliably detected using the nasal swab PCR assay. In this study, we evaluated the performance of the nasal swab MRSA PCR in predicting MRSA pneumonia. A retrospective cohort study was performed in a tertiary care center from January 2009 to July 2011. All patients with confirmed pneumonia who had both a nasal swab MRSA PCR test and a bacterial culture within predefined time intervals were included in the study. These data were used to calculate sensitivity, specificity, positive predictive value, and negative predictive value for clinically confirmed MRSA pneumonia. Four hundred thirty-five patients met inclusion criteria. The majority of cases were classified as either health care-associated (HCAP) (54.7%) or community-acquired (CAP) (34%) pneumonia. MRSA nasal PCR was positive in 62 (14.3%) cases. MRSA pneumonia was confirmed by culture in 25 (5.7%) cases. The MRSA PCR assay demonstrated 88.0% sensitivity and 90.1% specificity, with a positive predictive value of 35.4% and a negative predictive value of 99.2%. In patients with pneumonia, the MRSA PCR nasal swab has a poor positive predictive value but an excellent negative predictive value for MRSA pneumonia in populations with low MRSA pneumonia incidence. In cases of culture-negative pneumonia where initial empirical antibiotics include an MRSA-active agent, a negative MRSA PCR swab can be reasonably used to guide antibiotic de-escalation.