Methicillin-resistant Staphylococcus aureus nasal colonization is a poor predictor of intensive care unit-acquired methicillin-resistant Staphylococcus aureus infections requiring antibiotic treatment

Negative Nasal Methicillin-Resistant Staphylococcus aureus (MRSA) Polymerase Chain Reaction Rules Out Future MRSA Infections in Severely Injured Trauma Patients

Introduction: Studies have shown that methicillin-resistant Staphylococcus aureus (MRSA) polymerase chain reaction (PCR) swabs aid in de-escalating and decreasing the duration of antibiotic use in respiratory infections. However, the utility of MRSA PCR swabs is unknown for severely injured trauma patients. The aim of this study is to determine if negative MRSA PCR nasal swabs are associated with future MRSA infections in trauma patients admitted to the intensive care unit (ICU). Methods: Trauma patients admitted to the ICU that had a nasal MRSA PCR from July 2022 to March 2024 were evaluated. Demographics, as well as complication rates (including myocardial infarction, stroke, venous thromboembolism, acute respiratory distress syndrome, acute kidney injury), number and site of cultures obtained, days from MRSA PCR to culture, and positivity of a MRSA infection in those cultures, were evaluated. Results: In the study period, 65 severely injured patients were identified with an infection and nasal MRSA PCR. Most patients were male (74%), suffered a blunt mechanism (85%), and had a 28-day mortality rate of 36.9%. The median injury severity score was 26. Of the 65 injured patients, 7 (10.8%) had a positive MRSA PCR. There were 142 cultures obtained. No patient that had a negative PCR had a positive MRSA infection. The performance characteristics of a MRSA PCR swab included sensitivity (100%), specificity (92%), positive predictive value (29%), and negative predictive value (NPV, 100%). Conclusion: The incidence of MRSA-positive infections in trauma patients is low with a negative MRSA PCR swab, NPV of 100%. On the basis of these findings, there should be consideration of withholding empiric MRSA coverage in trauma ICU patients with a negative MRSA PCR. This may aid in reducing unnecessary antibiotic initiation and healthcare costs. Larger studies are needed to validate these findings and help delineate patients for which empiric MRSA coverage can be withheld.

[Epidemiology, diagnosis and treatment of adult patients with nosocomial pneumonia]

BACKGROUND

 Nosocomial pneumonia, encompassing hospital-acquired (HAP) and ventilator-associated pneumonia (VAP), remains a major cause of morbidity and mortality in hospitalized adults. In response to evolving pathogen profiles and emerging resistance patterns, this updated S3 guideline (AWMF Register No. 020-013) provides an evidence-based framework to enhance the diagnosis, risk stratification, and treatment of nosocomial pneumonia.

METHODS

 The guideline update was developed by a multidisciplinary panel representing key German professional societies. A systematic literature review was conducted with subsequent critical appraisal using the GRADE methodology. Structured consensus conferences and external reviews ensured that the recommendations were clinically relevant, methodologically sound, and aligned with current antimicrobial stewardship principles.

RESULTS

 For the management of nosocomial pneumonia patients should be divided in those with and without risk factors for multidrug-resistant pathogens and/or Pseudomonas aeruginosa. Bacterial multiplex-polymerase chain reaction (PCR) should not be used routinely. Bronchoscopic diagnosis is not considered superior to non-bronchoscopic sampling in terms of main outcomes. Combination antibiotic therapy is now reserved for patients in septic shock and high risk for multidrug-resistant pathogens, while select patients may be managed with monotherapy (e. g., meropenem). In clinically stabilized patients, antibiotic therapy should be de-escalated and focused, as well as duration shortened to 7-8 days. In critically ill patients, prolonged application of suitable beta-lactam antibiotics should be preferred. Patients on the intensive care unit (ICU) are at risk for invasive pulmonary aspergillosis (IPA). Diagnostics for Aspergillus should be performed with an antigen test from bronchial lavage fluid.

CONCLUSION

 This updated S3 guideline offers a comprehensive, multidisciplinary approach to the management of nosocomial pneumonia in adults. By integrating novel diagnostic modalities and refined therapeutic strategies, it aims to standardize care, improve patient outcomes, and enhance antimicrobial stewardship to curb the emergence of resistant pathogens.

Utility of MRSA nares PCR for non-respiratory cultures in critically ill patients: an observational evaluation

BACKGROUND

The overuse of antibiotics may lead to complications such as increased resistance, adverse events, and toxicities. Literature demonstrates a negative Methicillin-resistant Staphylococcus aureus (MRSA) nares polymerase chain reaction (PCR) may be used to streamline antibiotic therapy prior to respiratory culture results based on a negative predictive value (NPV) of 95-99%. Additional literature supports a high NPV when MRSA nares PCR is evaluated in non-respiratory cultures; however, this use in critically ill patients has not been studied.

OBJECTIVES

The purpose of this study was to evaluate the clinical utility of MRSA nares PCR in non-respiratory cultures in critically ill patients.

METHODS

This was a single centre, retrospective, cohort evaluation. Outcomes evaluated were NPV, positive predictive value (PPV), sensitivity, and specificity of MRSA nares PCR in critically ill patients. A sub-group analysis based on the site of culture (blood, urine, and wound) was also conducted.

RESULTS

Of the 325 patients screened, 200 critically ill patients were included for analysis. A total of 259 cultures were evaluated with blood being the most common source (n = 124). The MRSA nares PCR was positive in 34 (17%) patients and thirteen (5%) of the 259 cultures were positive for MRSA. For all cultures, the MRSA nares PCR demonstrated an NPV 99%, PPV 28%, sensitivity 77%, and specificity 85%. The subgroup analysis for the individual culture types reflected similar findings.

CONCLUSIONS

A negative MRSA nares PCR may be used to withhold initiation or allow for timely de-escalation of anti-MRSA antibiotics in critically ill patients if clinically applicable.

Key summary of German national guideline for adult patients with nosocomial pneumonia- Update 2024 Funding number at the Federal Joint Committee (G-BA): 01VSF22007

PURPOSE

This executive summary of a German national guideline aims to provide the most relevant evidence-based recommendations on the diagnosis and treatment of nosocomial pneumonia.

METHODS

The guideline made use of a systematic assessment and decision process using evidence to decision framework (GRADE). Recommendations were consented by an interdisciplinary panel. Evidence analysis and interpretation was supported by the German innovation fund providing extensive literature searches and (meta-) analyses by an independent methodologist. For this executive summary, selected key recommendations are presented including the quality of evidence and rationale for the level of recommendation.

RESULTS

The original guideline contains 26 recommendations for the diagnosis and treatment of adults with nosocomial pneumonia, thirteen of which are based on systematic review and/or meta-analysis, while the other 13 represent consensus expert opinion. For this key summary, we present 11 most relevant for everyday clinical practice key recommendations with evidence overview and rationale, of which two are expert consensus and 9 evidence-based (4 strong, 5 weak and 2 open recommendations). For the management of nosocomial pneumonia patients should be divided in those with and without risk factors for multidrug-resistant pathogens and/or Pseudomonas aeruginosa. Bacterial multiplex-polymerase chain reaction (PCR) should not be used routinely. Bronchoscopic diagnosis is not considered superior to´non-bronchoscopic sampling in terms of main outcomes. Only patients with septic shock and the presence of an additional risk factor for multidrug-resistant pathogens (MDRP) should receive empiric combination therapy. In clinically stabilized patients, antibiotic therapy should be de-escalated and focused. In critically ill patients, prolonged application of suitable beta-lactam antibiotics should be preferred. Therapy duration is suggested for 7-8 days. Procalcitonin (PCT) based algorithm might be used to shorten the duration of antibiotic treatment. Patients on the intensive care unit (ICU) are at risk for invasive pulmonary aspergillosis (IPA). Diagnostics for Aspergillus should be performed with an antigen test from bronchial lavage fluid.

CONCLUSION

The current guideline focuses on German epidemiology and standards of care. It should be a guide for the current treatment and management of nosocomial pneumonia in Germany.

Novel and Rapid Diagnostics for Common Infections in the Critically Ill Patient

There are several novel platforms that enhance detection of pathogens that cause common infections in the intensive care unit. These platforms have a sample to answer time of a few hours, are often higher yield than culture, and have the potential to improve antibiotic stewardship.

Predictive Value of Methicillin-Resistant Staphylococcus aureus Nasal Swab PCR Assay for MRSA Infection in Critically Ill Pediatric Patients

BACKGROUND

Critically ill pediatric patients are frequently initiated methicillin-resistant Staphylococcus aureus (MRSA) active antibiotics during infection evaluation even though MRSA infections are rare in many patient populations. The MRSA nasal swab polymerase chain reaction assay (MRSA-NS-PCR) is a test that has been shown to have a high negative predictive value (NPV) for MRSA infection in adults. This study evaluated the diagnostic test characteristics of the MRSA-NS-PCR in predicting the presence of MRSA infection in critically ill pediatric patients.

STUDY DESIGN

A retrospective cohort study was performed in a 44-bed pediatric intensive care unit (PICU) between 2013 and 2017. 3860 pediatric patients (54% male, median age 4 years [IQR 1-11 years]) admitted to the PICU who met pediatric systemic inflammatory response syndrome (pSIRS) criteria, were screened with a MRSA-NS-PCR, and had cultures obtained within seven days of MRSA-NS-PCR collection were included. Predictive values and post-test probabilities of the MRSA-NS-PCR for MRSA infection were calculated.

RESULTS

MRSA-NS-PCR was positive in 8.6% of patients. MRSA infection was identified in 40 patients, equaling an incidence rate of 2 per 1000 patient days. The MRSA-NS-PCR demonstrated a positive predictive value (PPV) of 9.7%, a NPV of 99.8%, and a post-test probability for a negative test of 0.2% for MRSA infection.

CONCLUSIONS

The MRSA-NS-PCR has a poor PPV but a high NPV for MRSA infection in PICU patients when the incidence of MRSA infection is low. Creation of protocols to guide antimicrobial selection based on MRSA-NS-PCR results may lead to improved antimicrobial stewardship and significant risk reduction.

Antimicrobial treatment imprecision: an outcome-based model to close the data-to-action loop

Health-care systems, food supply chains, and society in general are threatened by the inexorable rise of antimicrobial resistance. This threat is driven by many factors, one of which is inappropriate antimicrobial treatment. The ability of policy makers and leaders in health care, public health, regulatory agencies, and research and development to deliver frameworks for appropriate, sustainable antimicrobial treatment is hampered by a scarcity of tangible outcome-based measures of the damage it causes. In this Personal View, a mathematically grounded, outcome-based measure of antimicrobial treatment appropriateness, called imprecision, is proposed. We outline a framework for policy makers and health-care leaders to use this metric to deliver more effective antimicrobial stewardship interventions to future patient pathways. This will be achieved using learning antimicrobial systems built on public and practitioner engagement; solid implementation science; advances in artificial intelligence; and changes to regulation, research, and development. The outcomes of this framework would be more ecologically and organisationally sustainable patterns of antimicrobial development, regulation, and prescribing. We discuss practical, ethical, and regulatory considerations involved in the delivery of novel antimicrobial drug development, and policy and patient pathways built on artificial intelligence-augmented measures of antimicrobial treatment imprecision.

Diagnostic usefulness of serum procalcitonin in patients with bacterial sepsis

Background

The Sequential Organ Failure Assessment (SOFA) score is used for the diagnosis of sepsis and involves clinical and laboratory parameters that may not be readily and/or timely available in most resource-poor settings. Procalcitonin (PCT) has its level changed in response to bacterial sepsis and its measurement costs only a fraction of the total cost of investigations required to calculate SOFA score. This study aims to determine the diagnostic usefulness of PCT in bacterial sepsis.

Materials and Methods

Ninety-nine participants were studied, divided into three groups: apparently healthy volunteers, those with bacterial infection without sepsis (SOFA score <2), and patients with bacterial sepsis (positive culture and SOFA ≥2). PCT level of each participant was measured and median group levels compared. Pearson's correlation was used to determine the correlation between serum PCT levels and SOFA scores in the sepsis group using a significance level of 5 percent (P < 0.05). Diagnostic usefulness of PCT was assessed using receiver operating characteristic (ROC).

Result

Positive correlation was found between serum PCT levels and SOFA scores among patients with sepsis r = 0.42, P = 0.016. At a concentration of ≥4.25 ng/ml, serum PCT as a surrogate for SOFA score had a sensitivity and specificity of 57.60% and 84.80%, respectively, for indicating sepsis. The area under the ROC curve (AUC) was 0.74 (95% CI {0.62 to 0.86}, P = 0.001).

Conclusion

Serum PCT concentration was significantly higher in bacterial sepsis compared to bacterial infection without sepsis and healthy state. PCT concentration demonstrated positive correlation with SOFA score in bacterial sepsis and can be used as surrogate for sepsis screening/monitoring in resource-poor settings.

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.

Methicillin-Resistant Staphylococcus aureus Nasal Swab Is Insufficient to Withhold Empiric Methicillin-Resistant Staphylococcus aureus Pneumonia Coverage in a Trauma Population

INTRODUCTION

Methicillin-resistant staphylococcus aureus (MRSA) nasal colonization is a predictor of MRSA pneumonia in intensive care unit (ICU) patients. Negative nasal swabs have shown up to a 97% negative predictive value for MRSA pneumonia in nontrauma populations, though little investigation has been pursued in trauma patients.

MATERIALS AND METHODS

All trauma patients admitted to the ICU from April 2018 to February 2019 were screened for MRSA colonization by nasal swab. Patients with suspicion for pneumonia underwent bronchoalveolar lavage or quantitative sputum culture and were started on empiric antibiotic therapy based on the swab result. Swab-positive patients were started on empiric MRSA coverage and swab-negative patients were not.

RESULTS

MRSA nasal swab screening was performed in 601 trauma ICU patients. Ninety-six patients subsequently underwent pneumonia workup and were started on an empiric antibiotic regimen based on nasal swab results. Seventeen (17.7%) patients were MRSA nasal swab positive on screening, and 22 (22.9%) patients subsequently had significant growth of MRSA on quantitative respiratory culture. The sensitivity of nasal swab was 50.0% and the specificity was 91.9%. Eleven patients had a negative MRSA nasal swab but a positive MRSA pneumonia (11.5%). Patients with inadequate antibiotic coverage had statistically longer hospital length of stay, ICU length of stay, ventilator days, and rates of unplanned intubation compared to patients with adequate antibiotic coverage.

CONCLUSIONS

Nasal swab screening was not sensitive enough in a trauma population with a high endemic incidence of MRSA colonization to warrant withholding empiric antibiotic MRSA coverage in patients with suspected pneumonia.

Novel and Rapid Diagnostics for Common Infections in the Critically Ill Patient

There are several novel platforms that enhance detection of pathogens that cause common infections in the intensive care unit. These platforms have a sample to answer time of a few hours, are often higher yield than culture, and have the potential to improve antibiotic stewardship.

Evaluation of the Negative Predictive Value of Methicillin-Resistant Staphylococcus aureus Nasal Swab Screening in the Medical Intensive Care Units and Its Effect on Antibiotic Duration

Background

In addition to active surveillance of methicillin-resistant Staphylococcus aureus (MRSA) carrier, MRSA nasal screening can be valuable for antibiotic de-escalation. This study aimed to assess the correlations between the MRSA nasal swab and subsequent culture results in patients admitted to medical intensive care units (MICU). The impact of MRSA nasal swab on the antibiotic duration was also evaluated.

Materials and Methods

This retrospective study enrolled patients who received glycopeptides in the MICU of a medical center in 2019. Patients treated with glycopeptides for over 2 days before MICU admission were excluded. The associated data were collected through the electronic medical record system. The negative predictive value (NPV) of MRSA nasal swabs for MRSA infection was calculated, and their influence on empirical glycopeptide treatment duration was analyzed.

Results

Of the 338 patients who met the inclusion criteria, 277 underwent MRSA nasal screening. The NPV of MRSA-negative nasal swab for subsequent MRSA infection was 98.4%. The glycopeptide treatment duration of the patients with and without nasal screening was not significantly different (4.2 ± 2.8 vs 4.4 ± 3.0 days, p = 0.577). Of the 120 patients with MRSA-negative nasal swab and no subsequent MRSA infection, 75 continued empirical glycopeptides therapy. The additional treatment time was 3 days (interquartile range: 2–6 days).

Conclusion

The MRSA nasal swabs have high NPV for MRSA infection in critically ill patients. However, it has no impact on the empirical glycopeptide treatment duration. The value of MRSA nasal swabs should be advocated to optimize antibiotic therapy.

Antibiotic Decision-Making in the ICU

It is well established that Intensive Care Units (ICUs) are a focal point in antimicrobial consumption with a major influence on the ecological consequences of antibiotic use. With the high prevalence and mortality of infections in critically ill patients, and the clinical challenges of treating patients with septic shock, the impact of real life clinical decisions made by intensivists becomes more significant. Both under- and over-treatment with unnecessarily broad spectrum antibiotics can lead to detrimental outcomes. Even though substantial progress has been made in developing rapid diagnostic tests that can help guide antibiotic use, there is still a time window when clinicians must decide the empiric antibiotic treatment with insufficient clinical data. The continuous streams of data available in the ICU environment make antimicrobial optimization an ongoing challenge for clinicians but at the same time can serve as the input for sophisticated models. In this review, we summarize the evidence to help guide antibiotic decision-making in the ICU. We focus on 1) deciding IF: to start antibiotics, 2) choosing the spectrum of the empiric agents to use, and 3) de-escalating the chosen empiric antibiotics. We provide a perspective on the role of machine learning and artificial intelligence models for clinical decision support systems that can be incorporated seamlessly into clinical practice in order to improve the antibiotic selection process and, more importantly, current and future patients' outcomes.

Prospective Nasal Screening for Methicillin-Resistant Staphylococcus aureus in Critically Ill Patients With Suspected Pneumonia

We carried out a prospective de-escalation study based on methicillin-resistant Staphylococcus aureus (MRSA) nasal cultures in intensive care unit patients with suspected pneumonia. Days of anti-MRSA therapy was significantly reduced in the intervention group (2 [0–3] days vs 1 [0–2] day; P < .01). Time to MRSA de-escalation was also shortened in the intervention group.

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.

Predictive Value of the Methicillin-Resistant Staphylococcus aureus Nasal Swab for Methicillin-Resistant Staphylococcus aureus Ventilator-Associated Pneumonia in the Trauma Patient

Background: Many trauma centers have empiric treatment algorithms for ventilator-associated pneumonia (VAP) treatment prior to culture results that include antibiotic agents for methicillin-resistant Staphylococcus aureus (MRSA) coverage that can have adverse effects. This is the only study to evaluate risk factors and MRSA nasal swabs to risk-stratify trauma patients for MRSA VAP, thereby potentially limiting the need for empiric vancomycin. Patients and Methods: This was a single institution retrospective cohort study. Adult patients admitted to the trauma intensive care unit (ICU) between January 2013 and December 2017 who had a MRSA nasal swab and subsequently met criteria for VAP were included. Demographics, risk factors for MRSA pneumonia, and culture results were collected. Results: A total of 140 patients met inclusion criteria. The negative predictive value (NPV) of MRSA nasal swab at predicting subsequent MRSA pneumonia was 97%. The sensitivity, specificity, and positive predictive value were 50.0%, 96.2%, and 44.4%, respectively. Smokers were more likely to develop MRSA pneumonia, odds ratio: 7.0 (p = 0.02). When considering non-smokers with a negative MRSA nasal swab, NPV was 100%. Conclusions: This is the only study to date that assesses the utility of MRSA nasal swab and risk factor data to guide empiric VAP antibiotic therapy in trauma patients. Smoking was found to be a risk factor for MRSA pneumonia. The use of MRSA nasal swabs in combination with smoking status to guide empiric use of MRSA coverage antibiotic agents is recommended because of a 100% NPV. When utilized, as many as 68% of patients may safely be spared MRSA coverage antibiotic agents and the related adverse effects.

Utility of methicillin-resistant Staphylococcus aureus (MRSA) nasal screening in patients with acute myeloid leukemia (AML)

BACKGROUND

Current literature has demonstrated the utility of the MRSA nasal screen as a de-escalation tool to decrease unnecessary anti-MRSA antibiotic therapy. However, data on the applicability of this test in patients with hematologic malignancy is lacking.

METHODS

This is a single-center, retrospective cohort study of patients with acute myeloid leukemia (AML) with or without a history of hematopoietic cell transplant (HCT), with pneumonia and MRSA nasal screening with respiratory cultures obtained. The primary outcome was to determine the negative predictive value (NPV) of the MRSA nasal screen for MRSA pneumonia. Secondary outcomes included sensitivity, specificity, positive predictive value (PPV) of the MRSA nasal screen and prevalence of MRSA pneumonia.

RESULTS

Of 98 patients with AML and pneumonia, the prevalence of MRSA pneumonia was 4.1% with confirmed positive MRSA respiratory cultures observed in 4 patient cases. In patients with confirmed MRSA pneumonia, 3 had positive MRSA nasal screens while 1 had a false negative result, possibly due to a long lag time (21 days) between MRSA nasal screen and pneumonia diagnosis. Overall, the MRSA nasal screen demonstrated 75% sensitivity and 100% specificity, with a PPV of 100% and a NPV of 98.9%.

CONCLUSIONS

Given the low prevalence, empiric use of anti-MRSA therapy in those AML and HCT patients with pneumonia may not be warranted in clinically stable patients. For patients in whom empiric anti-MRSA antibiotics are initiated, nasal screening for MRSA may be utilized to de-escalate anti-MRSA antibiotics in patients with AML with or without HCT.

Evaluation of the timing of MRSA PCR nasal screening: How long can a negative assay be used to rule out MRSA-positive respiratory cultures?

PURPOSE

Previous studies indicate that the polymerase chain reaction (PCR) nasal assay for methicillin-resistant Staphylococcus aureus (MRSA) has a consistently high (>95%) negative predictive value (NPV) in ruling out MRSA pneumonia; however, optimal timing of PCR assay specimen and respiratory culture collection is unclear.

METHODS

A study including 736 patients from a community hospital system was conducted. Patients were included if they had undergone MRSA nasal screening with a PCR assay and had documented positive respiratory culture results.

RESULTS

In the full cohort, the MRSA PCR nasal screen assay was demonstrated to have an NPV of 94.9% (95% confidence interval [CI], 92.8%-96.5%) in ruling out MRSA-positive respiratory cultures. When evaluating the NPV by level of care (ie, where the MRSA PCR nasal assay sample was collected), no significant difference between values for samples collected in an intensive care unit vs medical/surgical units was identified (NPV [95%CI], 94.9% [92.7%-96.6%] vs 95.3% [88.4%-98.7%]). Additionally, NPV remained high with use of both invasive (NPV [95%CI], 96.8% [92.7%-99.0%]) and noninvasive (NPV [95%CI], 94.5% [91.7%-96.2%]) respiratory sampling methods. Finally, when evaluating the effect of time between MRSA PCR nasal screening and respiratory sample collection, we found high NPVs for all evaluated timeframes: within 24 hours, 93.8% (90.1%-96.4%); within 25 to 48 hours, 98.6% (92.7%-100.0%); within 49 hours to 7 days, 95.7% (91.4%-98.3%); within 8 to 14 days, 92.9% (85.1%-97.3%); and after more than 14 days, 95.5% (84.5%-99.4%).

CONCLUSION

We report high NPVs for up to 2 weeks between specimen collections, which allows clinicians to use a negative MRSA PCR nasal screen assay to rule out MRSA pneumonia, potentially leading to decreased exposure to MRSA-active antibiotics.

VanA rectal swab screening as a predictor of subsequent vancomycin-resistant enterococcal bloodstream infection in critically ill adults

OBJECTIVE

To evaluate whether vanA rectal screening for vancomycin-resistant Enterococcus (VRE) predicts vancomycin resistance for patients with enterococcal bloodstream infection (BSI).

DESIGN

A retrospective cohort study.

SETTING

Large academic medical center.

METHODS

The predictive performance of a vanA rectal swab was evaluated in 161 critically ill adults with an enterococcal BSI from January 1, 2007, to September 1, 2014, and who had a vanA rectal swab screening obtained within 14 days prior to blood culture.

RESULTS

Of the patients meeting inclusion criteria, 83 (51.6%) were vanA swab positive. Rectal-swab-positive patients were more likely to be younger, to be immunocompromised, to have an indwelling central vascular catheter, and to have a history of MDR bacteria. The vanA rectal swab had sensitivity and negative predictive values of 83.6% and 85.9%, respectively, and specificity and positive predictive values of 71.3% and 67.5%, respectively, for predicting a vancomycin-resistant enterococcal BSI in critically ill adults.

CONCLUSIONS

VanA rectal swabs may be useful for antimicrobial stewardship at institutions with VRE screening already in place for infection control purposes. A higher PPV would be warranted to implement a universal vanA screen on all ICU patients.

Impact of Nasal Swabs on Empiric Treatment of Respiratory Tract Infections (INSERT-RTI)

Methicillin-resistant Staphylococcusaureus (MRSA) polymerase-chain-reaction nasal swabs (PCRNS) are a rapid diagnostic tool with a high negative predictive value. A PCRNS plus education “bundle” was implemented to inform clinicians on the utility of PCRNS for anti-MRSA therapy de-escalation in respiratory tract infections (RTI). The study included patients started on vancomycin with a PCRNS order three months before and after bundle implementation. The primary objective was the difference in duration of anti-MRSA therapy (DOT) for RTI. Secondary objectives included hospital length of stay (LOS), anti-MRSA therapy reinitiation, 30-day readmission, in-hospital mortality, and cost. We analyzed 62 of 110 patients screened, 20 in the preintervention and 42 in the postintervention arms. Mean DOT decreased after bundle implementation by 30.3 h (p = 0.039); mean DOT for patients with a negative PCRNS decreased by 39.7 h (p = 0.014). Median cost was lower after intervention [USD$51.69 versus USD$75.30 (p < 0.01)]. No significant difference in LOS, mortality, or readmission existed. The bundle implementation decreased vancomycin therapy and cost without negatively impacting patient outcomes.

Methicillin-Resistant Staphylococcus aureus Infection and Treatment Options

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of infection worldwide, including a wide array of both hospital- and community-acquired infections-most commonly bacteremia, upper and lower respiratory tract infection, skin and soft-tissue infection, osteomyelitis, and septic arthritis. This chapter describes the epidemiology of MRSA infection, its ability to confer antibiotic resistance and produce a wide array of virulence factors, and its pivotal role in human infection, especially cystic fibrosis. It also provides an introduction to the strategies for treatment of both chronic and acute MRSA infections.

Screening of antibiotic-resistant staphylococci in the nasal cavity of patients and healthy individuals

The normal microbiota play critical roles in the general health of an individual and the functions of the microbiota colonized the nasal cavity in maintaining the health of the respiratory tract are well known. The nasal cavity is one of the potential bio-sources of the pathogenic opportunistic bacteria that have the ability to resist standard antibiotics. My aim was an evaluation of the prevalence of antibiotic-resistant staphylococci in the nasal cavity of healthy individuals and compared them with the strains isolated from patients. The work was designed as prospective, descriptive study in Medical University Hospital (MUH) and Botany and Microbiology Department, King Saud University (KSU), Riyadh, respectively. Strain isolation, purification, and preservation were performed according to standard protocols and the identification of pure bacterial cultures was carried out using a fully automatic system (VITEK 2 system). The isolates identified as Staphylococcus spp. were subjected to investigation. In patients, 34 out of 6668 isolates were Staphylococcus spp. obtained from the nasal cavity, while 32 out of 320 isolates from the nasal cavity of healthy individuals were Staphylococcus spp. The results confirmed that all the isolates were resistant to ampicillin and benzylpenicillin, but showed susceptibility to vancomycin, fusidic acid, gentamicin, linezolid, rifampicin, teicoplanin, tetracycline, and trimethoprim/sulfamethoxazole. A significant association (P < 0.05) was observed between all the isolates resistant to ampicillin and clindamycin in patients and healthy individuals. The antibiotic-resistant staphylococci are prevalent in the nasal cavity among healthy individuals and patients, and a statistically significant association exists between sources of bacterial isolates and antibiotic resistance.

Risk stratification and treatment of ICU-acquired pneumonia caused by multidrug- resistant/extensively drug-resistant/pandrug-resistant bacteria

PURPOSE OF REVIEW

Describe the risk factors and discuss the management of multidrug-resistant (MDR) bacteria responsible for pneumonia among critically ill patients, including methicillin-resistant Staphylococcus aureus, extended spectrum beta-lactamase-producing Enterobactericeae, carbapenem-resistant Enterobactericeae, multidrug resistant Pseudomonas aeruginosa, and Acinetobacter baumannii.

RECENT FINDINGS

Multiple factors have been associated with infections because of MDR bacteria, including prolonged hospital stay, presence of invasive devices, mechanical ventilation, colonization with resistant pathogens, and use of broad-spectrum antibiotics. Management of these infections includes the prompt use of appropriate antimicrobial therapy, implementation of antimicrobial stewardship protocols, and targeted active microbiology surveillance. Combination therapy and novel molecules have been used for the treatment of severe infections caused by resistant bacteria.

SUMMARY

The exponential increase of antimicrobial resistance among virulent pathogens currently represents one of the main challenges for clinicians in the intensive care unit. Knowledge of the local epidemiology, patient risk stratification, and infection-control policies remain key elements for the management of MDR infections. Results from clinical trials on new molecules are largely awaited.

Carriage of Methicillin-resistant Staphylococcus aureus in a Colony of Rhesus (Macaca mulatta) and Cynomolgus (Macaca fascicularis) Macaques

Methicillin-resistant Staphylococcus aureus (MRSA) carriage and infection are well documented in the human and veterinary literature; however only limited information is available regarding MRSA carriage and infection in laboratory NHP populations. The objective of this study was to characterize MRSA carriage in a representative research colony of rhesus and cynomolgus macaques through a cross-sectional analysis of 300 animals. MRSA carriage was determined by using nasal culture. Demographic characteristics of carriers and noncarriers were compared to determine factors linked to increased risk of carriage, and MRSA isolates were analyzed to determine antimicrobial susceptibility patterns, staphylococcal chromosome cassette mec (SCCmec) type, and multilocus sequence type (ST). Culture results demonstrated MRSA carriage in 6.3% of the study population. Animals with greater numbers of veterinary or experimental interventions including antibiotic administration, steroid administration, dental procedures, and surgery were more likely to carry MRSA. Susceptibility results indicated that MRSA isolates were resistant to β-lactams, and all isolates were resistant to between 1 and 4 non β-lactam antibiotics. In addition, 73.7% of MRSA isolates were identified as ST188-SCCmec IV, an isolate previously observed in an unrelated population of macaques and 15.8% were ST3268-SCCmec V, which has only been described in macaques. A single isolate had a novel sequence type, ST3478, and carried SCCmec V. These results suggest that NHP-adapted strains of MRSA exist and highlight the emergence of antimicrobial resistance in laboratory NHP populations.

Predictive characteristics of methicillin-resistant Staphylococcus aureus nares screening tests for methicillin resistance among S. aureus clinical isolates from hospitalized veterans

For patients with possible Staphylococcus aureus infection, providers must decide whether to treat empirically for methicillin-resistant S. aureus (MRSA). Nares MRSA colonization screening tests could inform decisions regarding empiric MRSA-active antibiotic use.1,2.

Healthcare-associated pneumonia: is there any reason to continue to utilize this label in 2019?

BACKGROUND

There is an ongoing controversy on the role of the healthcare-associated pneumonia (HCAP) label in the treatment of patients with pneumonia.

OBJECTIVE

To provide an update of the literature on patients meeting criteria for HCAP between 2014 and 2018.

SOURCES

The review is based on a systematic literature search using PubMed-Central full-text archive of biomedical and life sciences literature at the U.S. National Institutes of Health's National Library of Medicine (NIH/NLM).

CONTENT

Studies compared clinical characteristics of patients with HCAP and community-acquired pneumonia (CAP). HCAP patients were older and had a higher comorbidity. Mortality rates in HCAP varied from 5% to 33%, but seemed lower than those cited in the initial reports. Criteria behind the HCAP classification differed considerably within populations. Microbial patterns differed in that there was a higher incidence of methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, and, to a lesser extent, enterobacteriaceae. Definitions and rates of multidrug-resistant (MDR) pneumonia also varied considerably. Broad-spectrum guideline-concordant treatment did not reduce mortality in four observational studies. The HCAP criteria performed poorly as a predictive tool to identify MDR pneumonia or pathogens not covered by treatment for CAP. A new score (Drug Resistance in Pneumonia, DRIP) outperformed HCAP in the prediction of MDR pathogens. Comorbidity and functional status, but not different microbial patterns, seem to account for increased mortality.

IMPLICATIONS

HCAP should no longer be used to identify patients at risk of MDR pathogens. The use of validated predictive scores along with implementation of de-escalation strategies and careful individual assessment of comorbidity and functional status seem superior strategies for clinical management.

Rapid Detection of Methicillin-Resistant Staphylococcus aureus in BAL: A Pilot Randomized Controlled Trial

BACKGROUND

Guidelines recommend empirical vancomycin or linezolid for patients with suspected pneumonia at risk for methicillin-resistant Staphylococcus aureus (MRSA). Unneeded vancomycin or linezolid use may unnecessarily alter host flora and expose patients to toxicity. We therefore sought to determine if rapid testing for MRSA in BAL can safely decrease use of vancomycin or linezolid for suspected MRSA pneumonia.

METHODS

Operating characteristics of the assay were initially validated against culture on residual BAL. A prospective, unblinded, randomized clinical trial to assess the effect of antibiotic management made on the basis of rapid diagnostic testing (RDT) compared with usual care was subsequently conducted, with primary outcome of duration of vancomycin or linezolid administration. Secondary end points focused on safety.

RESULTS

Sensitivity of RPCR was 95.7%, with a negative likelihood ratio of 0.04 for MRSA. The clinical trial randomized 45 patients: 22 to antibiotic management made on the basis of RDT and 23 to usual care. Duration of vancomycin or linezolid administration was significantly reduced in the intervention group (32 h [interquartile range, 22-48] vs 72 h [interquartile range, 50-113], P < .001). Proportions with complications and length of stay trended lower in the intervention group. Hospital mortality was 13.6% in the intervention group and 39.1% for usual care (95% CI of difference, -3.3 to 50.3, P = .06). Standardized mortality ratio was 0.48 for the intervention group and 1.18 for usual care.

CONCLUSIONS

A highly sensitive BAL RDT for MRSA significantly reduced use of vancomycin and linezolid in ventilated patients with suspected pneumonia. Management made on the basis of RDT had no adverse effects, with a trend to lower hospital mortality.

TRIAL REGISTRY

ClinicalTrials.gov; No. NCT02660554; URL: www.clinicaltrials.gov.

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.

Low incidence of multidrug-resistant bacteria and nosocomial infection due to a preventive multimodal nosocomial infection control: a 10-year single centre prospective cohort study in neurocritical care

Background

Nosocomial infection (NI) control is an important issue in neurocritical care due to secondary brain damage and the increased morbidity and mortality of primary acute neurocritical care patients. The primary aim of this study was to determine incidence of nosocomial infections and multidrug-resistant bacteria and seek predictors of nosocomial infections in a preventive multimodal nosocomial infection protocol in the neurointensive care unit (NICU). The secondary aim focused on their impact on stay, mortality and cost in the NICU.

Methods

A10-year, single-centre prospective observational cohort study was conducted on 3464 acute brain disease patients. There were 198 (5.7%) patients with nosocomial infection (wound 2.1%, respiratory 1.8%, urinary 1.0%, bloodstream 0.7% and other 0.1%); 67 (1.9%) with Extended spectrum beta-lactamase (ESBL); 52 (1.5%) with Methicillin-resistant Staphylococcus aureus (MRSA), nobody with Vancomycin-resistant enterococcus (VRE). The protocol included hygienic, epidemiological status and antibiotic policy. Univariate and multivarite logistic regression analysis was used for identifying predictors of nosocomial infection.

Results

From 198 NI patients, 153 had onset of NI during their NICU stay (4.4%; wound 1.0%, respiratory 1.7%, urinary 0.9%, bloodstream 0.6%, other 0.1%); ESBL in 31 (0.9%) patients, MRSA in 30 (0.9%) patients. Antibiotics in prophylaxis was given to 63.0% patients (59.2 % for operations), in therapy to 9.7% patients. Predictors of NI in multivariate logistic regression analysis were airways (OR 2.69, 95% CI 1.81-3.99, p<0.001), urine catheters (OR 2.77, 95% CI 1.00-7.70, p=0.050), NICU stay (OR 1.14, 95% CI 1.12-1.16, p<0.001), transfusions (OR 1.79, 95% CI 1.07-2.97, p=0.025) antibiotic prophylaxis (OR 0.50, 95% CI 0.34-0.74, p<0.001), wound complications (OR 2.30, 95% CI 1.33-3.97, p=0.003). NI patients had longer stay (p<0.001), higher mortality (p<0.001) and higher TISS sums (p<0.001) in the NICU.

Conclusions

The presented preventive multimodal nosocomial infection control management was efficient; it gave low rates of nosocomial infections (4.2%) and multidrug-resistant bacteria (ESBL 0.9%, MRSA 0.9% and no VRE). Strong predictors for onset of nosocomial infection were accesses such as airways and urine catheters, NICU stay, antibiotic prophylaxis, wound complications and transfusion. This study confirmed nosocomial infection is associated with worse outcome, higher cost and longer NICU stay.

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.

Active identification of patients who are methicillin-resistant Staphylococcus aureus colonized is not associated with longer duration of vancomycin therapy

BACKGROUND

Excessive prescribing of vancomycin among patients admitted to inpatient wards is a challenge for antimicrobial stewardship programs, especially in the setting of expanded screening programs for methicillin-resistant Staphylococcus aureus (MRSA). Studies examining factors associated with longer duration of vancomycin use are limited.

METHODS

We conducted a retrospective cohort study to assess the impact of universal MRSA admission screening on duration of vancomycin use at the VA Boston Healthcare System during the period from January 2013-November 2015.

RESULTS

A total of 2,910 patients were administered intravenous vancomycin during the study period. A clinical culture positive for MRSA was strongly associated with vancomycin administration lasting >72 hours (odds ratio [OR], 2.72; 95% confidence interval [CI], 1.86-3.97; P < .001). After controlling for clinical culture results, admission MRSA colonization was not associated with vancomycin use past 72 hours (OR, 0.94; 95% CI, 0.8-1.1). A negative MRSA nasal swab on admission had a high negative predictive value for all MRSA infections evaluated (99.6% for pneumonia, 99.6% for bloodstream infection, and 98.1% for skin and soft tissue infection).

CONCLUSIONS

Admission surveillance for MRSA nasal colonization is not a major driver of prolonged vancomycin use. A negative admission MRSA nasal screen may be a useful tool for antimicrobial stewardship programs to limit vancomycin use, particularly in noncritically ill patients.

Active surveillance for carbapenem-resistant Acinetobacter baumannii in a medical intensive care unit: Can it predict and reduce subsequent infections and the use of colistin?

BACKGROUND

Infection caused by carbapenem-resistant Acinetobacter baumannii (CRAB) has become a major problem in intensive care units (ICUs), with high incidence and mortality. This prospective study investigated the diagnostic value and influence of active surveillance, followed by isolation and enhanced contact precaution (IECP), on the subsequent CRAB infection and colistin use.

METHODS

The study prospectively enrolled 1,115 patients who were admitted to the medical ICU of Chonnam National University Hwasun Hospital between April 2011 and November 2014. Active surveillance cultures were obtained from the throat or trachea, skin, and urine. IECP was performed beginning April 2013.

RESULTS

Active surveillance detected CRAB in 168 (15%) patients and CRAB infection developed in 70 (6%) patients. Endotracheal tube was independently associated with both CRAB colonization and infection, whereas IECP was inversely associated with both CRAB colonization and infection in multivariate analysis (all P values <.001). The sensitivity, specificity, and positive and negative predictive values of active surveillance for subsequent CRAB infection were 84%, 90%, 47%, and 98%, respectively. The rate of CRAB acquisition, CRAB infection, and the use of colistin were significantly lower during the IECP period compared with the control period (6.5 vs 34.1, 2.6 vs 14.7, and 19.9 vs 65.5 per 1,000 patient-days, respectively; all P <.001).

CONCLUSIONS

Active surveillance has good specificity and negative predictive value for subsequent CRAB infection. Active surveillance followed by IECP was inversely associated with the acquisition of CRAB and subsequent CRAB infection, and was associated with a reduction in colistin use in ICU patients.

Methicillin-Resistant Staphylococcus aureus Pneumonia in Critically Ill Trauma and Burn Patients: A Retrospective Cohort Study

BACKGROUND

The timing and risk factors for methicillin-resistant Staphylococcus aureus (MRSA) pneumonia in trauma patients are not well characterized. This information is critical for the selection of appropriate empiric antibiotics. The objective of this study was to determine the incidence of MRSA pneumonia in early-onset and late-onset pneumonia and to identify risk factors for MRSA in the trauma-burn intensive care unit (ICU).

PATIENTS AND METHODS

We conducted a retrospective cohort study from January 2012 to March 2015 of patients in the trauma and burn ICU with clinical and microbiologic evidence of pneumonia. Demographics, injury type and severity, co-morbidities, antimicrobial agents, and MRSA nasal colonization at ICU admission were extracted from the medical record. A multi-variable exact logistic regression was performed to assess predictors of MRSA pneumonia.

RESULTS

Eighty patients with 88 episodes of pneumonia were included in the cohort. Ten patients had MRSA pneumonia, an overall incidence of 11.4% of pneumonia episodes with a median onset of seven days. The proportion of MRSA pneumonia episodes was not significantly different in early-onset (<5 days) or late-onset pneumonia, and there were no statistically significant risk factors for developing MRSA pneumonia. The majority of patients with MRSA had at least one known risk factor including homelessness, substance abuse, and receipt of broad-spectrum antibiotic agents.

CONCLUSIONS

The 11.4% overall incidence of MRSA pneumonia in this trauma-burn cohort was similar to what has been reported in other trauma populations, although MRSA was equally likely to be identified in early- and late-onset pneumonia. Our results suggest that risk factors other than duration of hospitalization may be important considerations in the decision to initiate MRSA-active empiric therapy for pneumonia in the trauma-burn ICU.

Genetic Lineages of Methicillin-Resistant Staphylococcus aureus Acquired during Admission to an Intensive Care Unit of a General Hospital

OBJECTIVES

The objectives of this study were to determine the frequency of methicillin-resistant Staphylococcus aureus (MRSA) colonization or infection while on admission to the intensive care unit (ICU), and examine the genetic backgrounds of the MRSA isolates to establish transmission among the patients.

SUBJECTS AND METHODS

This study involved screening 2,429 patients admitted to the ICU of Farwania Hospital from January 2005 to October 2007 for MRSA colonization or infection. The MRSA isolates acquired after admission were investigated using a combination of molecular typing techniques to determine their genetic backgrounds.

RESULTS

Of 2,429 patients screened, 25 (1.0%) acquired MRSA after admission to the ICU. Of the 25 MRSA, 19 (76%) isolates belonged to health care-associated (HA-MRSA) clones: ST239-III (n = 17, 68%) and ST22-IV (n = 2, 8%). The remaining 6 MRSA isolates belonged to community-associated clones: ST80-IV (n = 3, 12%), ST97-IV (n = 2, 8%), and ST5-IV (n = 1, 4%). The ST239-III-MRSA clone was associated with infection as well as colonization, and was isolated from patients from 2005 to 2007.

CONCLUSIONS

The HA-MRSA clone ST239-III persistently colonized patients admitted to the ICU, indicating the possibility of its transmission among the patients over time.

Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.These guidelines are intended for use by healthcare professionals who care for patients at risk for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), including specialists in infectious diseases, pulmonary diseases, critical care, and surgeons, anesthesiologists, hospitalists, and any clinicians and healthcare providers caring for hospitalized patients with nosocomial pneumonia. The panel's recommendations for the diagnosis and treatment of HAP and VAP are based upon evidence derived from topic-specific systematic literature reviews.

Update on ventilator-associated pneumonia

PURPOSE OF REVIEW

To highlight the importance of escalating pathogen resistance in ventilator-associated pneumonia (VAP) along with diagnostic and treatment implications.

RECENT FINDINGS

In a period of rising bacterial resistance, VAP remains an important infection occurring in critically ill patients. Risk factors for multidrug-resistant pathogens depend on both local epidemiology and host factors. New diagnostic techniques and antimicrobials can help with rapid bacterial identification and timely and appropriate treatment while avoiding emergence of bacterial resistance.

SUMMARY

Clinicians should be aware of risk factors for multidrug-resistant pathogens causing VAP and also of particularities of diagnosis and treatment of this important clinical entity.

Usefulness of previous methicillin-resistant Staphylococcus aureus screening results in guiding empirical therapy for S aureus bacteremia

Staphylococcus aureus bacteremia (SAB), which may be caused by methicillin-resistant S aureus (MRSA), is a leading cause of bloodstream infections. SAB and MRSA can cause an increase in mortality, result in longer hospital stays and increase medical costs. However, it is possible that MRSA colonization may predict infection. Using a retrospective cohort investigation, this study evaluated the clinical utility of past MRSA screening swabs for predicting methicillin resistance and its use in guiding empirical antibiotic therapy for SAB.

BACKGROUND:

Staphylococcus aureus bacteremia (SAB) is an important infection. Methicillin-resistant S aureus (MRSA) screening is performed on hospitalized patients for infection control purposes.

OBJECTIVE:

To assess the usefulness of past MRSA screening for guiding empirical antibiotic therapy for SAB.

METHODS:

A retrospective cohort study examined consecutive patients with confirmed SAB and previous MRSA screening swab from six academic and community hospitals between 2007 and 2010. Diagnostic test properties were calculated for MRSA screening swab for predicting methicillin resistance of SAB.

RESULTS:

A total of 799 patients underwent MRSA screening swabs before SAB. Of the 799 patients, 95 (12%) had a positive and 704 (88%) had a negative previous MRSA screening swab. There were 150 (19%) patients with MRSA bacteremia. Overall, previous MRSA screening swabs had a positive likelihood ratio of 33 (95% CI 18 to 60) and a negative likelihood ratio of 0.45 (95% CI 0.37 to 0.54). Diagnostic accuracy differed depending on mode of acquisition (ie, community-acquired, nosocomial or health care-associated infection) (P<0.0001) and hospital (P=0.0002). At best, for health care-associated infection, prior MRSA screening swab had a positive likelihood ratio of 16 (95% CI 9 to 28) and a negative likelihood ratio of 0.27 (95% CI 0.17 to 0.41).

CONCLUSIONS:

A negative prior MRSA screening swab cannot reliably rule out MRSA bacteremia and should not be used to guide empirical antibiotic therapy for SAB. A positive prior MRSA screening swab greatly increases likelihood of MRSA, necessitating MRSA coverage in empirical antibiotic therapy for SAB.

Risk Factors of Methicillin-Resistant Staphylococcus aureus Infection and Correlation With Nasal Colonization Based on Molecular Genotyping in Medical Intensive Care Units: A Prospective Observational Study

Methicillin-resistant Staphylococcus aureus (MRSA) is a common and important cause of colonization and infection in medical intensive care units (ICU). The aim of this study was to assess association factors between MRSA nasal colonization and subsequent infections in medical ICU patients by clinical investigation and molecular genotyping. A prospective cohort observational analysis of consecutive patients admitted to medical ICUs between November 2008 and May 2010 at a tertiary teaching hospital were included. To detect MRSA colonization, the specimens from the nares were obtained within 3 days of admission to the ICU and again 1 week following admission to the ICU. Genetic relatedness for colonized and clinical isolates from each study patient with MRSA infection were analyzed and compared. A total of 1266 patients were enrolled after excluding 195 patients with already present MRSA infections. Subsequent MRSA infection rates were higher in patients with nasal colonization than in those without (39.1% versus 14.7%, respectively). Multivariate Poisson regression analysis demonstrated that nasal MRSA colonization (relative risk [RR]: 2.50; 95% confidence interval [CI]: 1.90-3.27; P < 0.001) was independent predictors for subsequent MRSA infections. History of tracheostomy, however, was a protective predictor in all patients (RR: 0.38; 95% CI: 0.18-0.79; P = 0.010) and in patients with MRSA nasal colonization (RR: 0.22; 95% CI: 0.55-0.91; P = 0.037). Molecular genetics studies revealed that most MRSA isolates were healthcare-associated clones and that nasal and clinical isolates exhibited up to 75% shared identity. Methicillin-resistant S. aureus nasal colonization was significantly associated with subsequent MRSA infection among medical ICU patients. Previous MRSA infection was associated with subsequent MRSA infections, and history of tracheostomy associated with reducing this risk. Most MRSA isolates were healthcare-associated strains that were significantly correlated between nasal and clinical isolates.

Nasal methicillin-resistant Staphylococcus aureus polymerase chain reaction: a potential use in guiding antibiotic therapy for pneumonia

CONTEXT

The role at admission of nasal polymerase chain reaction (PCR) for patients with methicillin-resistant Staphylococcus aureus (MRSA) in guiding antibiotic therapy for lower respiratory tract infection is unknown.

OBJECTIVE

To determine whether nasal MRSA PCR at admission can predict the absence of MRSA in lower respiratory tract secretions.

DESIGN

We performed a retrospective study of adult patients admitted to a large urban hospital. Patients had a nasal MRSA PCR test and a lower respiratory tract culture obtained within 48 hours of admission and the culture yielded S aureus.

MAIN OUTCOME MEASURES

Sensitivity, specificity, and positive and negative predictive values.

RESULTS

Our results showed high sensitivity (93.3%) and negative predictive value (95.2%) of nasal PCR for MRSA in the lower respiratory tract.

CONCLUSION

With its high sensitivity and negative predictive value, a nasal MRSA PCR test performed within 48 hours of hospital admission could help guide the discontinuation of MRSA-directed empiric antibiotic therapy in patients who are unlikely to be infected with this organism. A prospective study is needed to confirm these findings.

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.

The prevalence and significance of methicillin-resistant Staphylococcus aureus colonization at admission in the general ICU Setting: a meta-analysis of published studies

OBJECTIVE

To estimate the prevalence and significance of nasal methicillin-resistant Staphylococcus aureus colonization in the ICU and its predictive value for development of methicillin-resistant S. aureus infection.

DATA SOURCES

MEDLINE and EMBASE and reference lists of all eligible articles.

STUDY SELECTION

Studies providing raw data on nasal methicillin-resistant S. aureus colonization at ICU admission, published up to February 2013. Analyses were restricted in the general ICU setting. Medical, surgical, and interdisciplinary ICUs were eligible. ICU studies referring solely on highly specialized ICUs populations and reports on methicillin-resistant S. aureus outbreaks were excluded.

DATA EXTRACTION

Two authors independently assessed study eligibility and extrapolated data in a blinded fashion. The two outcomes of interest were the prevalence estimate of methicillin-resistant S. aureus nasal colonization at admission in the ICU and the sensitivity/specificity of colonization in predicting methicillin-resistant S. aureus-associated infections.

DATA SYNTHESIS

Meta-analysis, using a random-effect model, and meta-regression were performed. Pooled data extracted from 63,740 evaluable ICU patients provided an estimated prevalence of methicillin-resistant S. aureus nasal colonization at admission of 7.0% (95% CI, 5.8-8.3). Prevalence was higher for North American studies (8.9%; 95% CI, 7.1-10.7) and for patients screened using polymerase chain reaction (14.0%; 95% CI, 9.6-19). A significant per year increase in methicillin-resistant S. aureus colonization was also noted. In 17,738 evaluable patients, methicillin-resistant S. aureus infections (4.1%; 95% CI, 2.0-6.8) developed in 589 patients. The relative risk for colonized patients was 8.33 (95% CI, 3.61-19.20). Methicillin-resistant S. aureus nasal carriage had a high specificity (0.96; 95% CI, 0.90-0.98) but low sensitivity (0.32; 95% CI, 0.20-0.48) to predict methicillin-resistant S. aureus-associated infections, with corresponding positive and negative predictive values at 0.25 (95% CI, 0.11-0.39) and 0.97 (95% CI, 0.83-1.00), respectively.

CONCLUSIONS

Among ICU patients, 5.8-8.3% of patients are colonized by methicillin-resistant S. aureus at admission, with a significant upward trend. Methicillin-resistant S. aureus colonization is associated with a more than eight-fold increase in the risk of associated infections during ICU stay, and methicillin-resistant S. aureus infection develops in one fourth of patients who are colonized with methicillin-resistant S. aureus at admission to the ICU.

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.

MRSA nasal colonization in children: prevalence meta-analysis, review of risk factors and molecular genetics

BACKGROUND

We report a meta-analysis of methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization prevalence in children and a review of the risk factors as well as molecular genetic characterization.

METHODS

All relevant studies reporting prevalence data on MRSA nasal colonization in children published between January 2000 and August 2010 were retrieved from the MEDLINE database and analyzed.

RESULTS

After screening 544 studies, 50 studies were included. We obtained an estimate of MRSA prevalence of 2.7% (95% confidence interval [CI]: 2.2-3.1); of 5.2% (95% CI: 3.1-7.3) in children with underlying conditions and of 2.3% (95% CI: 1.8-2.7) in healthy children; 5.4% (95% CI: 3.1-7.7) in children recruited in hospitals and 3% (95% CI: 2.4-3.6) in children recruited in the community. Staphylococcal cassette chromosome mec type IV is the most diffused cassette globally.

CONCLUSION

The hospital remains the environment where the microorganism circulates most. Children with underlying conditions could act as vectors of microorganisms between the hospital and the community. MRSA prevention strategies should be tailored to each specific institution, taking into account the nosocomial prevalence of MRSA nasal colonization and infections, and the prevalence of nasal colonization in the community that refers to the specific health care center.