Methicillin-resistant Staphylococcus Aureus Nasal Screening Research Articles

Ventilator-Associated Methicillin-Resistant Staphylococcus aureus (MRSA) Pneumonia in a Patient with a Negative MRSA Nasal Swab.

BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) pneumonia is associated with high morbidity and mortality. Recently, MRSA testing by nasal swab has been utilized to "exclude" pneumonia caused by MRSA, given its high negative-predictive value (NPV). We present, however, a case of MRSA pneumonia diagnosed by endotracheal aspirate culture (EAC) in a patient with a negative MRSA nasal swab. CASE REPORT A 58-year-old woman presented with septic shock and respiratory failure. Chest X-ray (CXR) on admission was unrevealing; however, computed tomography (CT) revealed multifocal pneumonia. Intensive Care Unit (ICU)-level care was required for mechanical ventilation and vasopressors. She initially improved with treatment of community-acquired pneumonia (CAP) and was extubated on hospital day 6; however, she then developed a fever, tachycardia, and respiratory distress necessitating re-intubation later that day. Repeat CXR demonstrated a new left lower lobe infiltrate. Blood cultures were drawn and vancomycin and cefepime were started to cover for ventilator-associated pathogens. An EAC and nasal swab were collected to test for MRSA. The next day (day 7), the MRSA nasal swab returned negative, and vancomycin was discontinued. Our patient continued to experience fevers, worsening leukocytosis, and ongoing vasopressor need. On hospital day 9, the EAC results were obtained, and were positive for MRSA. Vancomycin was restarted and our patient recovered. CONCLUSIONS Negative MRSA nasal screening may be considered grounds to de-escalate empiric MRSA antibiotics if MRSA prevalence is low. However, in critically ill patients with high risk and suspicion for MRSA pneumonia, discontinuing empiric MRSA coverage should be done with caution or clinicians should wait until respiratory culture results are obtained before de-escalating antibiotics.

Hiding in Plain Sight: Benefit of Abrasion and Laceration Swabs in Identification of Panton-Valentine Leucocidin (PVL)-Meticillin Resistant Staphylococcus aureus (MRSA) Colonisation in Military Personnel.

Background Outbreaks of Panton-Valentine Leucocidin (PVL)-producing methicillin-resistantStaphylococcus aureus(MRSA) skin and soft tissue infections (SSTIs) are a recurrent challenge for the Royal Marines at the Commando Training Centre (CTCRM). The intensity of commando training, its impact on skin integrity, and persistent colonisation reservoirs within the training centre have thwarted attempts to prevent these outbreaks. Aim To present an outbreak of PVL-producing MRSA SSTIs at a military training centre, demonstrating the benefit of additional abrasion and laceration swabs on the identification of colonised personnel and showing the effectiveness of a 10-day decolonisation regime. Method Following the identification of the outbreak of PVL-producing MRSA, all 36 members of the Recruit Troop underwent nasal MRSA screening to identify MRSA carriers. The screening was repeated on day 16 after completing an enhanced 10-day decolonisation regime. A third screening was conducted on the 110th day after a second peak of infection was identified. Various infection control measures, such as enhanced cleaning, restriction of movement and adjustments to the military training serials, were introduced to prevent further spread through the training centre. Results In this outbreak, two-thirds (eighteen) of the Recruit Troop suffered MRSA-PVL skin infections requiring antibiotic therapy and three required hospital admission for surgical management of their abscesses. The outbreak lasted 130 days, with two spikes in infections 10 weeks apart. The outbreak was successfully confined to one troop. Conclusion With concerns about low identification rates of carriers using nasal screening for MRSA, in this outbreak, we improved the identification of asymptomatic carriage with the simple step of additional culture swabs for all cuts and abrasions. Improved identification of colonised recruits, along with an enhanced decolonisation regime and rigid infection control practices, prevented the further spread of the clone through the training centre. In a population with constant ongoing skin trauma, such as the military, contact sport athletes and iIV drug users, our results show that a culture of suitable abrasions/lacerations will improve the identification of MRSA colonisation compared with nasal swabs alone. Despite ongoing skin trauma and the logistical difficulties in delivering effective decolonisation during military training, decolonisation was successful in 79% of recruits after one decolonisation and 87% after the second 10-day decolonisation.

Evaluating Methicillin-Resistant Staphylococcus aureus Polymerase Chain Reaction Nasal Screening as a Tool for Antimicrobial Stewardship

IntroductionInitiation of broad-spectrum empiric antibiotics is common when infection is suspected in hospitalized adults. The benefits of early utilization of effective antibiotics are well documented. However, the negative effects of inappropriate antibiotic use have led to antimicrobial stewardship mandates. Recent data demonstrate the utility of methicillin-resistant Staphylococcus aureus (MRSA) polymerase chain reaction (PCR) nasal screening to steward anti-MRSA empiric antibiotics in pneumonia. We hypothesize that MRSA PCR nasal swabs would also be effective to rule out other MRSA infection to effectively limit unnecessary antibiotics for any infectious source. MethodsWe performed a single-center retrospective chart review of all adult patient encounters from October 2019-July 2021 with MRSA PCR nasal testing. We then reviewed all charts to evaluate for the presence of infections based on source cultures results, as the gold standard. Sensitivity, specificity, negative predictive value, and positive predictive value were calculated from 2 × 2 contingency tables. ResultsAmong all patients with MRSA nasal screening, 1189 patients had any infection. Prevalence of MRSA nasal carriage among patients screened was 12%. Prevalence of MRSA infection among all infections was 7.5%. MRSA nasal swabs demonstrated a negative predictive value of 100% for MRSA urinary tract infection, 97.9% for MRSA bacteremia, 97.8% for MRSA pneumonia, 92.1% for MRSA wound infection, and 96.6% for other MRSA infections. Overall, MRSA PCR nasal swabs had a sensitivity of 68.5%, specificity of 90.1%, positive predictive value of 23.7%, and negative predictive value of 98.5% for any infections. ConclusionsMRSA PCR nasal swabs have a high negative predictive value for all infections. Our data support the use of MRSA PCR nasal swabs to rule out MRSA infection and thereby allow early de-escalation of MRSA coverage in hospitalized patients requiring empiric antibiotics. Implementation of MRSA screening could decrease antibiotic-associated morbidity, resistance, and costs. More studies should be conducted to validate these results and support these findings.

Does a Positive Methicillin-Resistant Staphylococcus aureus (MRSA) Nasal Screen Predict the Risk for MRSA Skin and Soft Tissue Infection?

Skin and soft tissue infections (SSTIs) are often caused by gram-positive bacteria that colonize the skin. Given the overuse of antibiotics, SSTIs are increasingly caused by resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). Guidance on the utility of MRSA nasal screening for MRSA SSTI is limited. To determine whether MRSA nasal screening predicts the risk of MRSA SSTIs. This was a single-center, retrospective cohort study of adult patients with an SSTI diagnosis that had MRSA nasal screening and wound cultures obtained within 48 hours of starting antibiotics. Sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratios were calculated using VassarStats. Pretest and posttest probabilities were estimated with Microsoft Excel. A total of 884 patient encounters were reviewed between December 1, 2018, and October 31, 2021, and 300 patient encounters were included. The prevalence of MRSA SSTI was 18.3%. The MRSA nasal colonization had a sensitivity of 63.6%, specificity of 93.9%, positive predictive value of 70.0% (95% CI = 55.2%-81.7%), negative predictive value of 92.0% (95% CI = 87.7%-94.9%), positive likelihood ratio of 10.39 (95% CI = 6.12-17.65), negative likelihood ratio of 0.39 (95% CI = 0.27-0.55), positive posttest probability of 70.0%, and negative posttest probability of 8.0%. Given the high positive likelihood ratio, a positive MRSA nasal screen was associated with a large increase in the probability of MRSA SSTI at our institution, and a negative MRSA nasal screen was associated with a small but potentially significant decrease in the probability of MRSA SSTI.

The Clinical Value of Methicillin-Resistant Staphylococcus aureus Nasal Screening in the Management of Diabetic Foot Infections.

Nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) remains an important risk factor for diabetic foot infections (DFIs). We explored herein the clinical value of MRSA-nasal screening in the management of DFIs. In this retrospective case-control study, patients admitted with a DFI between 1/1/2014-6/30/2020 were studied and divided into cases (positive MRSA-nasal screening) and controls (negative MRSA-nasal). We included 171 patients (22 cases and 149 controls). MRSA nasal screening had a negative predictive value (NPV) of 86%. Compared to controls, cases were treated with intravenous vancomycin for a longer duration: (median [IQR], 5[3,11] vs 2[2,6]) days, P = .037). In multivariate analysis, a negative MRSA nasal screening was associated with a 74% decreased risk of AKI (OR = 0.26, 95% CI = 0.07-0.89). MRSA nasal screening in patients admitted with DFI has a high NPV. Obtained early, it can shorten the duration of intravenous vancomycin, consequently preventing AKI.

234. Does nasal screening for methicillin resistant Staphylococcus aureus (MRSA) prevent deep surgical site infections for elective cervical spinal fusion?

<h3>BACKGROUND CONTEXT</h3> Preoperative MRSA screening and decolonization has demonstrated success for some orthopaedic subspecialties in prevention of surgical site infections (SSIs). Spine surgery, however, has seen varied results, potentially secondary to the anatomic and surgical heterogeneity of the patients included in prior studies. Given that prior research has demonstrated greater propensity for gram positive SSIs in the cervical spine, we sought to investigate if MRSA screening would be more impactful in the cervical spine. <h3>PURPOSE</h3> The purpose of this study was to determine the relationship between nasal MRSA testing and SSI rates specifically in the setting of primary posterior cervical instrumented spine surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study. <h3>PATIENT SAMPLE</h3> Adult patients undergoing primary instrumented posterior cervical procedures from January 2015-December 2019 at two tertiary academic referral centers in an urban setting <h3>OUTCOME MEASURES</h3> Physiologic measures: subfascial presumed infected collection or abscess within 90 days of the index operation. <h3>METHODS</h3> Adult patients undergoing primary instrumented posterior cervical procedures from January 2015-December 2019 were reviewed for MRSA testing < 90-days before surgery, preoperative mupirocin, perioperative antibiotics and SSI defined as operative incision and drainage (I&D) < 90-days after surgery. Trauma, tumor and infection cases were excluded. Logistic regression modeling was used with SSI the primary outcome and MRSA screening the primary predictor with clinical and demographic factors as covariates. <h3>RESULTS</h3> This study included 668 patients, of whom MRSA testing was performed in 212 patients (31.7%) and 6 (2.8%) were colonized with MRSA. Twelve patients (1.8%) underwent an I&D. On adjusted analysis, preoperative MRSA testing was not associated with postoperative I&D risk. Perioperative vancomycin similarly had no association with postoperative I&D risk. Notably, six patients (50%) grew MSSA from intraoperative cultures, with no cases of MRSA. <h3>CONCLUSIONS</h3> There was no association between preoperative nasal MRSA screening and SSIs in primary posterior cervical instrumented procedures, nor was there any association between vancomycin or infection rate. Furthermore, there was a preponderance of gram-positive infections but none caused by MRSA. Given these findings, the considerable cost and effort associated with MRSA testing in the setting of primary posterior cervical instrumentation may not be justified. Further research should investigate if higher-risk scenarios demonstrate greater utility of preoperative testing. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Does Nasal Screening for Methicillin-Resistant Staphylococcus aureus (MRSA) Prevent Deep Surgical Site Infections for Elective Cervical Spinal Fusion?

Retrospective cohort study. The objective of this study was to determine the relationship between nasal methicillin-resistant Staphylococcus aureus (MRSA) testing and surgical site infection (SSI) rates in the setting of primary posterior cervical instrumented spine surgery. Preoperative MRSA screening and decolonization has demonstrated success for some orthopedic subspecialties in prevention of SSIs. Spine surgery, however, has seen varied results, potentially secondary to the anatomic and surgical heterogeneity of the patients included in prior studies. Given that prior research has demonstrated greater propensity for gram positive SSIs in the cervical spine, we sought to investigate if MRSA screening would be more impactful in the cervical spine. Adult patients undergoing primary instrumented posterior cervical procedures from January 2015 to December 2019 were reviewed for MRSA testing <90 days before surgery, preoperative mupirocin, perioperative antibiotics, and SSI defined as operative incision and drainage (I&D) <90 days after surgery. Logistic regression modeling used SSI as the primary outcome, MRSA screening as primary predictor, and clinical and demographic factors as covariates. This study included 668 patients, of whom MRSA testing was performed in 212 patients (31.7%) and 6 (2.8%) were colonized with MRSA. Twelve patients (1.8%) underwent an I&D. On adjusted analysis, preoperative MRSA testing was not associated with postoperative I&D risk. Perioperative vancomycin similarly had no association with postoperative I&D risk. Notably, 6 patients (50%) grew methicillin sensitive Staphylococcus aureus from intraoperative cultures, with no cases of MRSA. There was no association between preoperative nasal MRSA screening and SSIs in primary posterior cervical instrumented procedures, nor was there any association between vancomycin or infection rate. Furthermore, there was a preponderance of gram positive infections but none caused by MRSA. Given these findings, the considerable cost and effort associated with MRSA testing in the setting of primary posterior cervical instrumentation may not be justified. Further research should investigate if higher-risk scenarios demonstrate greater utility of preoperative testing.

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

BackgroundIn 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 MethodsThis 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.ResultsOf 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).ConclusionThe 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.

Effectiveness of an electronic health system-based best-practice advisory to enhance the time to de-escalation of vancomycin for respiratory indications.

Methicillin-resistant Staphylococcus aureus (MRSA) infection is highly unlikely when nasal-swab results are negative. We evaluated the impact of an electronic prompt regarding MRSA nasal screening on the length of vancomycin therapy for respiratory indications. Retrospective, single-center cohort study. Tertiary-care academic medical center (Mayo Clinic) in Jacksonville, Florida. Eligible patients received empiric treatment with vancomycin for suspected or confirmed respiratory infections from January through April 2019 (preimplementation cohort) and from October 2019 through January 2020 (postimplementation cohort). The electronic health system software was modified to provide a best-practice advisory (BPA) prompt to the pharmacist upon order verification of vancomycin for patients with suspected or confirmed respiratory indications. Pharmacists were prompted to order a MRSA nasal swab if it was not already ordered by the provider. We reviewed patient records to determine the time from vancomycin prescription to de-escalation. The secondary end point was incidence of acute kidney injury. The study included 120 patients (preimplementation, n = 61; postimplementation, n = 59). Median time to de-escalation was significantly shorter for the postimplementation cohort: 76 hours (interquartile range [IQR], 52-109) versus 42 hours (IQR, 37-61; P = .002). Acute kidney injury occurred in 11 patients (18%) in the preimplementation cohort and in 3 patients (5%) in the postimplementation cohort (P = .01; number needed to treat, 8). Implementation of a BPA notification for MRSA nasal screening helped decrease the time to de-escalation of vancomycin.

247. The Predictive Value of Methicillin-Resistant Staphylococcus aureus Surveillance Swabs in Septic Arthritis

BackgroundSeptic arthritis is a destructive form of acute arthritis secondary to infection. With an annual incidence of 2 to 5 cases per 100 000 individuals, it is associated with significant morbidity and mortality. Prompt source control and antimicrobial therapy remain the mainstays of management. Epidemiology, microbiology studies, and local resistance patterns are important in guiding therapeutic decisions. Staphylococcal and streptococcal species are the most common pathogens with Methicillin-resistant Staphylococcus aureus (MRSA) becoming an increasingly important pathogen. The increasing incidence of MRSA provides clinicians with the challenge of deciding which patients require empiric coverage for MRSA. MRSA nasal screening has been shown to have a high negative predictive value in pneumonia, bloodstream infections, and nosocomial infections in critically ill patients. However, little is known about the diagnostic utility of MRSA surveillance swabs for predicting MRSA infections in septic arthritis. MethodsA retrospective cohort study was performed in 3 tertiary hospitals from September 1, 2010 to December 31, 2020. All adult patients with confirmed septic arthritis of the ankle, wrist, knee, or hip and an MRSA surveillance swab performed within 72 hours of admission were included in the study. These data were used to calculate the sensitivity, specificity, positive predictive value and negative predictive value for MRSA surveillance swabs. ResultsOne hundred seventy-two patients met inclusion criteria. Thirty patients had positive MRSA surveillance swabs. The prevalence of MRSA in joint cultures was 11.04%. The positive predictive value of MRSA surveillance swabs was 42.3% and the negative predictive value was 93.5% in all participants. The MRSA surveillance swab had a negative predictive value of 100% in participants with no risk factors for MRSA colonization. ConclusionThe negative predictive value of MRSA surveillance swabs used independently is insufficient to confidently rule out MRSA as the causative pathogen in septic arthritis. When used in combination with MRSA risk factors, the absence of MRSA risk factors may help clinicians rule out MRSA as a causative pathogen. Disclosures All Authors: No reported disclosures

The evaluation of five commercial bacteriophage cocktails against methicillin-resistant Staphylococcus aureus isolated from nasal swab samples.

Infections due to methicillin-resistant Staphylococcus aureus (MRSA) are a growing concern for public health resulting in increase in morbidity, length of hospital stay, and cost of treatment. MRSA nasal swab screening may give clinicians additional information for decision of empiric antimicrobial agents. While increasing antibiotic resistance leads to new treatment approaches, bacteriophages are one of the most promising methods for these alternatives. It was aimed to determine the effectiveness of bacteriophages against MRSA isolates. Nasal swab samples were collected from outpatients without any evidence of infection who applied to Hatay, Mersin and Gaziantep family and immigration health centers. A series (35) were isolated from Turkish patients, and G series (64) were isolated from Syrian immigrants. Methicillin resistance was determined phenotypically and genotypically. Also, antibiotic susceptibilities of all isolates were determined against erythromycin, clindamycin, gentamicin, linezolid, rifampicin, and mupirocin. The total antimicrobial resistance rates of isolates were found to be 11%, 28%, 8%, 5%, 16%, 19%, and 29% respectively. The high susceptibility rate against ciprofloxacin (88.8%) was remarkable. The overall susceptibility of MRSA strains to ENKO, INTESTI, PYO, SES, and staphylococcal bacteriophages was 67.7%, 55.5%, 53.5%, 61.6% and 44.4%, respectively.The antibiotic susceptibility rates (except erythromycin) and efficacy of bacteriophages were higher in group A. Considering that high efficacy rates were not achieved in the study and the sensitivity rates of Turkish isolates to all phages were found to be higher than those of Syrian isolates, searching for phages in the geographic regions where the pathogen is common may be helpful to obtain suitable phages for treatment.

9. The impact of nasal screening for methicillin-resistant staphylococcus aureus on surgical site infection after primary lumbar fusion

<h3>BACKGROUND CONTEXT</h3> Surgical site infections (SSI) constitute significant morbidity in spine surgery. Efforts at SSI prevention include preoperative methicillin-resistant Staphylococcus aureus (MRSA) screening and decolonization, with demonstrated success for arthroplasty patients along with vascular and cardiothoracic surgical patients. The variety of surgical approaches and anatomic regions within spine surgery can limit the impact of analyses at the subspecialty level. Despite the success of MRSA nasal screening and decolonization in reducing SSI rates in other disciplines, the impact on spine surgery is less understood. <h3>PURPOSE</h3> To determine the relationship between nasal MRSA testing and operative debridement rates for surgical site infection after primary lumbar fusion. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study at two academic tertiary referral centers. <h3>PATIENT SAMPLE</h3> Adult patients (>18 years) were identified from January 2015 to March 2020 based on CPT codes for spinal instrumentation and fusion. Inclusion criteria were primary instrumented posterior lumbar fusion between 1-3 levels and exclusion criteria were revision surgery, tumor, infection, lateral-only surgery or operative surgeon with fewer than 20 cases. <h3>OUTCOME MEASURES</h3> Operative incision and drainage (I&D) of the index lumbar spine wound within 90-days after surgery was the primary outcome. <h3>METHODS</h3> Chart text, operative reports and laboratory reports were reviewed for data abstraction. Multivariable logistic regression modeling assessed for demographic differences between MRSA testing groups as well as factors contributing to I&D risk. <h3>RESULTS</h3> There were 2,148 patients included with a mean age 62.5 (SD 12.9), 56.9% female, and mean BMI 29.4 (SD 6.2). MRSA testing 90 days prior to surgery was completed in 884 (41.1%) of patients, and 19 (2.2%) of tested patients were colonized with MRSA preoperatively. Thirty-six (1.7%) patients underwent surgical I&D within 90 days of their index procedure for a surgical site infection. I&D risk was not associated with presence or result of MRSA testing, preoperative mupirocin prescriptions, or type of intraoperative antibiotic after controlling for surgeon. I&D risk was associated with higher BMI (5.7% increased risk for every 1 unit increase in BMI or a coefficient of 0.057, 95% confidence interval 0.017 to 0.097, p = 0.005) after controlling for age, diabetes and smoking status. <h3>CONCLUSIONS</h3> The present study demonstrates no difference in surgical I&D rates between patients who underwent MRSA testing, who had positive MRSA colonization or who underwent other interventions aimed at decreasing SSI rates such as preoperative mupirocin decolonization or addition of intraoperative vancomycin. Increased BMI was associated with risk of undergoing an operative I&D for surgical site infection, suggesting that patient factors dominate over clinical interventions in the prevention of surgical site infection after primary lumbar spine fusion. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

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

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. 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. 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%). 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.

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.

Performance of nasal methicillin-resistant Staphylococcus aureus screening for intra-abdominal infections in critically ill adult patients.

Intra-abdominal infections (IAIs) are a common reason for intensive care unit (ICU) admissions, and methicillin-resistant Staphylococcus aureus (MRSA) is an uncommon pathogen in IAIs. Although more data are available in the setting of non-abdominal sources, there are limited data on the performance of nasal MRSA screening for MRSA IAIs. The primary objective of this study was to evaluate the performance of nasal MRSA screening for MRSA IAIs in critically ill adult patients. This was a multicenter, retrospective, cohort study. A 14-hospital healthcare system between January 1, 2014, and August 31, 2019. Adult patients admitted to an ICU for at least 24 h with a diagnosis code for an IAI, a nasal MRSA surveillance screen within 30 days, and an intra-abdominal culture were eligible for inclusion. The primary outcome was to evaluate the performance of nasal MRSA screening for MRSA IAIs by calculating the accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Out of 863 patients randomly screened, a total of 192 patients were included. The study population had a mean age of 60 (SD ±15) years, and 101 (53%) patients were male. Six (3.1%) patients were positive for an MRSA IAI, of which four (66.7%) demonstrated a positive nasal MRSA screen. A total of 186 (96.8%) patients were negative for a MRSA IAI, of which 19 (10.2%) were nasal MRSA-positive and 167 (89.8%) were nasal MRSA-negative. Nasal MRSA screening demonstrated the following performance: accuracy 89.1% (95% CI: 83.8%-93.1%), sensitivity 66.7% (95% CI: 22.3%-95.7%), specificity 89.8% (95% CI: 84.5%-93.7%), PPV 17.4% (95% CI: 9.4%-30.0%), and NPV 98.8% (95% CI: 96.4%-99.6%). There were no significant differences in clinical outcomes, including renal replacement-free days, ICU and hospital length of stay, and in-hospital mortality. Among critically ill adult patients with IAIs, a negative nasal MRSA screen within 30days may help to empirically exclude MRSA as a causative pathogen.

Effectiveness of Methicillin-Resistant Staphylococcus aureus (MRSA) Nasal Screening for Reduction of Vancomycin Use for Pneumonia

Background: Methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization has been a well-established risk for developing MRSA pneumonia. In previous studies, the MRSA nasal screening test has shown an excellent negative predictive value (NPV) for MRSA pneumonia in patients without exclusion criteria such as mechanical ventilation, hemodynamic instability, cavitary lesions, and underlying pulmonary disease. MRSA nasal screening can be used as a stewardship tool to de-escalate broad antibiotic coverage, such as vancomycin. Objective: The purpose of this study was to determine whether implementation of a MRSA nasal screening questionnaire improves de-escalation of vancomycin for patients with pneumonia. Methods: A retrospective review was performed on 250 patients from October 2018 to January 2019 who received MRSA nasal screening due to their prescriber choosing only “respiratory” on the vancomycin dosing consult form. Data obtained included demographics and clinical outcomes. Statistical analyses were performed, and P &lt; .05 was considered significant. Results: Of the 250 patients screened, only 19 patients (8%) were positive for MRSA. Moreover, 40% of patients met exclusion criteria. In 149 patients without exclusion criteria, the MRSA nasal swab had a 98% NPV. Although not statistically significant, vancomycin days of therapy (DOT) based on MRSA nasal swab result was 1 day shorter in those with negative swabs (3.49 days negative vs 4.58 days positive; P = .22). Vancomycin DOT was significantly reduced in pneumonia patients without exclusion criteria (3.17 days “no” vs 4.17 days “yes”; P = .037). Conclusions: The implementation of an electronic MRSA nasal screening questionnaire resulted in reduced vancomycin DOT in pneumonia patients at UAB Hospital. The MRSA nasal swab is an effective screening tool for antibiotic de-escalation based on its 98% NPV for MRSA pneumonia if utilized in the correct patient population.Funding: NoneDisclosures: Rachael Anne Lee reports a speaker honoraria from Prime Education, LLC.

Methicillin-Resistant Staphylococcus aureus (MRSA) Admission Screening in the Neonatal Intensive Care Unit (NICU): Algorithm for Hospital Transfers

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent source of infection in the neonatal intensive care unit (NICU). Due to the serious consequences associated with MRSA infections in neonates, much effort has been made to prevent and control epidemics in NICUs. Since 2006, our hospital has performed MRSA nasal surveillance screening of all newborns in the NICU in accordance with the recommendations of the Chicago-Area Neonatal MRSA Working Group. In 2017, a MRSA infection was identified in a newborn shortly after transfer from an outside hospital and who had an initial negative MRSA admission screen. As a result, we modified the admission screening process for all transfers from outside NICUs. Methods: The Evanston Hospital Infant Special Care Unit is a level 3 NICU in the northern suburbs of Chicago with 44 NICU beds and 450 admissions per year. Effective July 1, 2017, all NICU transfers have a nasal MRSA screen performed upon admission and after 48 hours. The transferred baby is placed on contact isolation until both screening results return negative. Nasal MRSA testing is performed using both PCR on the BD MAX MRSA Assay platform and is confirmed by culture using MRSA CHROMagar TM. Results: Between July 1, 2017, and October 31, 2019, 112 neonates were transferred from outside NICUs. Moreover, 105 (94%) had at least 1 MRSA screen completed and 99 (88%) had both MRSA screens completed. Of 99 with 2 screens, only 1 neonate had an initial positive nasal MRSA screen. Of the remaining 98 negative babies, none had a repeat positive nasal MRSA screen within 48 hours of admission. of 99 neonates with 2 serial admission MRSA screens, 82 (83%) were transferred within 48 hours of birth. In addition, 17 neonates were transferred &gt;48 hours after birth, including the 1 MRSA-positive baby. Conclusions: In an attempt to identify all potential MRSA-positive neonates transferred to our NICU, we instituted a policy of 2 admission nares swabs. However, our data suggest that a single initial MRSA swab may be sufficient. If continued collection of a second screen is performed, it may be sufficient to screen babies who have been hospitalized for at least 48 hours prior to transfer, which eliminates 83% of admission testing and results in a cost savings.Funding: NoneDisclosures: None

Pharmacist-Driven MRSA Nasal PCR Screening and the Duration of Empirical Vancomycin Therapy for Suspected MRSA Respiratory Tract Infections.

ObjectiveTo assess the effect of a pharmacist-driven, polymerase chain reaction (PCR)−based nasal screening protocol for methicillin-resistant Staphylococcus aureus (MRSA) on vancomycin therapy duration and on rates of adverse drug events and 30-day hospital readmission.Patients and MethodsFrom July 8, 2017, through January 31, 2019, we performed a retrospective, multicenter, preimplementation-postimplementation study. Patients with a vancomycin order to treat lower respiratory tract infection (LRTI) underwent MRSA PCR screening; tests were ordered by health care providers, including physicians, physician assistants, and advanced practice registered nurses. During the preimplementation period (July 8, 2017, through September 30, 2018), pharmacists could order MRSA PCR screening only after receiving a verbal order from a health care provider. During the postimplementation period (October 1, 2018, through January 31, 2019), a collaborative practice agreement allowed pharmacists to order MRSA PCR screening tests.ResultsThe preimplementation group included 241 patients, and the postimplementation group included 74 patients. Of these patients, 124 in the preimplementation group and 62 in the postimplementation group received MRSA PCR screening. Twenty patients (16.1%) in the preimplementation group and 9 (14.5%) in the postimplementation group had a positive MRSA PCR screening test result (between-group difference, 1.6%; P=.80). Duration of therapy was significantly shorter in the postimplementation group (median [interquartile range], 14.3 [5.0-28.6] hours vs 24.0 [12.4-47.0] hours; P<.001).ConclusionVancomycin therapy carries a risk of adverse events and may increase health care costs. A pharmacist-driven protocol for MRSA nasal swab PCR screening effectively reduces the duration of vancomycin therapy for patients with lower respiratory tract infection.

Methicillin-resistant Staphylococcus aureus (MRSA) screening upon inpatient hospital admission: Is there concordance between nasal swab results and samples taken from skin and soft tissue?

Methicillin-resistant Staphylococcus aureus (MRSA) infections are associated with increased mortality and healthcare costs. In 2007, a Veterans' Affairs (VA) hospital implemented a MRSA nasal screening program, following a nationwide VA mandate, in an effort to reduce healthcare-associated MRSA infections. To evaluate the correlation between the nasal screening results for MRSA and culture results of wound and tissue sites. This retrospective study was conducted on inpatients at our VA hospital. Patients were included if they had undergone nasal screening for MRSA plus culture of a wound or tissue site within 30 days of hospital admission. In total, 337 patients underwent nasal screening and wound culture and 211 underwent nasal screening and wound and tissue cultures. The prevalence of MRSA nasal colonization was 14.2% for wound samples and 15.2% for tissue samples. The sensitivities of MRSA nasal screening for detecting MRSA were 64.6% for wound cultures and 65.5% for tissue cultures. Specificities were 86.2% and 88.8% for wound and tissue cultures, respectively. The positive predictive values (PPVs) were 43.7% and 51.2% for wound and tissue cultures, respectively, and the negative predictive values (NPVs) were high at 93.6% and 93.5%, respectively. In cases of wound or tissue samples for which culture results are pending, a negative MRSA nasal swab may be a component of the decision to withhold or discontinue MRSA-active agents.

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

To describe the diagnostic performance characteristics of methicillin-resistant Staphylococcus aureus (MRSA) nasal screening for patients with pneumonia. 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). Relevant studies in humans and English were considered. 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. 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.