Methicillin-resistant Staphylococcus Aureus Test 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.

Molecular Identification of Marine Symbiont Bacteria of Holothuria scabra from Tanjung Tiram Beach and its Potential as a Methicilin-Resistant Staphylococcus aureus Antibacterial agent

The resistance of Staphylococcus aureus may occur to many types of antibiotics, especially in the cases of noncompliance in using antibiotics, which is likely to allow the evolution of Multi-Drug Resistant (MDR) bacteria. Holothuria scabra are marine invertebrates that were reported being capable of producing secondary metabolites as antibacterial MDR. The purpose of the study was to identify the Holothuria scabra symbiont bacteria found in Tanjung Tiram, southern Konawe, South Sulewesi, which has the ability to produce antibacterial compounds against MRSA (Methicillin-Resistant Staphylococcus aureus). The stages of this research began with the isolation of bacteria, antibacterial activity test, DNA extraction, amplification by PCR 16S rDNA and sequencing. The results of the study showed that 9 isolates of bacteria were isolated from Holothuria scabra, those are HS1, HS2, HS3, HS4, HS5, HS6, HS7, HS8 and HS9. Among them, 2 isolates showed highest activity against MRSA test bacteria. The highest activities were displayed by HS2 and HS3 isolates code with the largest inhibition zone were 35mm and 36mm. The molecular identification of HS2 isolate has 72% homology with Streptomyces albus, while HS3 isolate has 97% homology with Streptomyces albus.

Change in Methicillin-Resistant Staphylococcus aureus Testing in the Intensive Care Unit as an Antimicrobial Stewardship Initiative.

Background: Methicillin-resistant Staphylococcus aureus (MRSA)-associated infections are a cause of morbidity and mortality in the intensive care unit (ICU). Vancomycin is a treatment option but is not without risks. Methods: A MRSA testing change-the switch from culture to polymerase chain reaction-was implemented at 2 adult (tertiary and community) ICUs located in a Midwestern US health system. Data from 2016 to 2020 were included in the study, and the median change in time to test results was examined. Results: During the study period, 71% of 19,975 patients seen at the 2 ICUs received MRSA testing. In the preintervention period, 91% and 99% of patients at the tertiary and community hospitals received testing via culture, respectively. Culture testing was used 1% and ∼0% of the time at the tertiary and community hospitals, respectively, in the postintervention period. A counterfactual estimate showed 36 (95% credible interval [CrI], 35, 37) and 32 (95% CrI, 31, 33) fewer hours until results were available at the tertiary and community hospitals, respectively. Conclusion: After the testing change, MRSA results were available in less time. Obtaining results sooner can assist with antimicrobial stewardship through the potential delay in initiating therapies such as vancomycin and/or quicker de-escalation of such therapies.

1804. Quality Improvement Project to improve empiric antibiotic therapy for skin and soft tissue infections using the nasal MRSA PCR

Abstract Background Large cohort studies from the Veteran’s Administration support the negative predictive value of the methicillin resistant Staphylococcus aureus (MRSA) nasal polymerase chain reaction (PCR) swabs for skin and soft tissue infection (SSTI). We investigated the use of the nasal MRSA PCR swab to reduce the inappropriate empiric use of vancomycin and piperacillin-tazobactam for SSTI at our institution. Methods Between July and August 2021, we educated Hospital Internal Medicine (HIM) and Internal Medicine Residents (IMR) on the basics of SSTI management and the utility of a negative nasal MRSA PCR swab. Data on empiric use of vancomycin and piperacillin-tazobactam for SSTIs were collected 3/1/2021 to 7/1/2021 (pre-intervention) and 8/30/2021 to 12/29/2021 (post-intervention). We excluded patients who didn’t have an SSTI, weren’t managed by IMR or HIM, and whose empiric antibiotics were for another indication. To account for antibiotics started in the emergency department (ED), a patient was regarded as having received appropriate empiric antibiotics if they were de-escalated in the first 24 hours of being admitted to IMR or HIM. Example of education material. These fliers were distributed to resident rooms following a series of noon conferences Results Pre-intervention there were 106 patient encounters. In 56 of these (52.8%), patients were placed on inappropriate empiric antibiotics. Post-intervention, there were 72 patient encounters. In 23of these (31.9%), patients were placed on inappropriate empiric antibiotic for an absolute risk reduction (ARR) of 20.9% with a statistically significant 95% CI (6.522 - 35.249) and a number needed to treat (NNT) of 4.78. Nasal MRSA PCR testing increased from 40.6% to 56.9%. The ARR among the HIM teams was 21.3% and was statistically significant with a 95% CI (4.24 - 38.394). Their proportion of MRSA testing increased from 41.5% to 50%. The IMR teams had an ARR of 14.8%, which was not statistically significant (95% CI, -11.339 to 40.884). Their MRSA nasal PCR testing increased from 37.5% to 72%. Conclusion Education on SSTI treatment coupled with use of the MRSA nares PCR appeared to improve empiric antibiotic choices. Residents stated that the nasal MRSA PCR facilitated empiric antibiotic choice. Positive ARR was seen in whole and sub-group analyses of physician teams. We theorize that the lack of statistical significance in the IMR group was related to a small sample size. Disclosures All Authors: No reported disclosures.

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.

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.

Nasal screening for methicillin-resistant Staphylococcus aureus does not reduce surgical site infection after primary lumbar fusion

BACKGROUND CONTEXTPreoperative methicillin-resistant Staphylococcus aureus (MRSA) testing and decolonization has demonstrated success for arthroplasty patients in surgical site infections (SSIs) prevention. Spine surgery, however, has seen varied results. PURPOSEThe purpose of this study was to determine the impact of nasal MRSA testing and operative debridement rates on surgical site infection after primary lumbar fusion. STUDY DESIGN/SETTINGRetrospective cohort study and/or Consolidated medical enterprise PATIENT SAMPLEAdult patients undergoing primary instrumented lumbar fusions from January 2015 to December 2019 were reviewed. OUTCOME MEASURESThe primary outcome was incision and drainage performed in the operating room within 90 days of surgery. METHODSMRSA testing <90-day’s before surgery, mupirocin prescription <30-day’s before surgery, perioperative antibiotics, and Elixhauser comorbidity index were collected for each subject. Bivariate analysis used Wilcoxon rank-sum testing and logistic regression modeling Multivariable logistic regression modeling assessed for associations with MRSA testing, intravenous vancomycin use, and I&D rate. RESULTSThe study included 1,884 patients for analysis, with mean age of 63.1 (SE 0.3) and BMI 29.5 (SE 0.1). MRSA testing was performed in 755 patients (40.1%) and was more likely to be performed in patients with lower Elixhauser index scores (OR 0.98, 95% CI 0.96–0.99, p=.021) on multivariable analysis. Vancomycin use increased significantly over time (OR 1.49 and/or year, 95% CI 1.3–1.8, p<.001) despite no change in mupirocin or I&D rates. MRSA testing, mupirocin prescriptions, perioperative parenteral vancomycin use, and intrawound vancomycin powder use had no impact on I&D rates. I&D risk was associated with higher BMI (OR 1.06, 95% CI 1.02–1.12, p=.009) and higher number of blood product units transfused (OR 1.23, 95% CI 1.03–1.46, p=.022). CONCLUSIONSThe present study demonstrates no impact on surgical I&D rates from the use of preoperative MRSA testing. Increased BMI and transfusions were associated with operative I&D rates for surgical site infection. As a result of the hospital directive, vancomycin use increased over time with no associated change in infection rates, underscoring the need for focused interventions, and engagement with antibiotic stewardship programs.

Isolation, characterization, anti-MRSA evaluation, and in-silico multi-target anti-microbial validations of actinomycin X2 and actinomycin D produced by novel Streptomyces smyrnaeus UKAQ_23

Streptomyces smyrnaeus UKAQ_23, isolated from the mangrove-sediment, collected from Jubail,Saudi Arabia, exhibited substantial antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA), including non-MRSA Gram-positive test bacteria. The novel isolate, under laboratory-scale conditions, produced the highest yield (561.3 ± 0.3 mg/kg fermented agar) of antimicrobial compounds in modified ISP-4 agar at pH 6.5, temperature 35 °C, inoculum 5% v/w, agar 1.5% w/v, and an incubation period of 7 days. The two major compounds, K1 and K2, were isolated from fermented medium and identified as Actinomycin X2 and Actinomycin D, respectively, based on their structural analysis. The antimicrobial screening showed that Actinomycin X2 had the highest antimicrobial activity compared to Actinomycin D, and the actinomycins-mixture (X2:D, 1:1, w/w) against MRSA and non-MRSA Gram-positive test bacteria, at 5 µg/disc concentrations. The MIC of Actinomycin X2 ranged from 1.56–12.5 µg/ml for non-MRSA and 3.125–12.5 µg/ml for MRSA test bacteria. An in-silico molecular docking demonstrated isoleucyl tRNA synthetase as the most-favored antimicrobial protein target for both actinomycins, X2 and D, while the penicillin-binding protein-1a, was the least-favorable target-protein. In conclusion, Streptomyces smyrnaeus UKAQ_23 emerged as a promising source of Actinomycin X2 with the potential to be scaled up for industrial production, which could benefit the pharmaceutical industry.

Association between length of residence and prevalence of MRSA colonization among residents in geriatric long-term care facilities

BackgroundA high prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization has been reported among residents in geriatric long-term care facilities (LTCFs). Some studies indicate that MRSA might be imported from hospitals into LTCFs via resident transfer; however, other studies report that high MRSA prevalence might be caused by cross-transmission inside LTCFs. We aimed to assess which factors have a large impact on the high MRSA prevalence among residents of geriatric LTCFs.MethodsWe conducted a cohort study among 260 residents of four geriatric LTCFs in Japan. Dividing participants into two cohorts, we separately analyzed (1) the association between prevalence of MRSA carriage and length of LTCF residence (Cohort 1: n = 204), and (2) proportion of residents identified as MRSA negative who were initially tested at admission but subsequently identified as positive in secondary testing performed at ≥2 months after their initial test (Cohort 2: n = 79).ResultsAmong 204 residents in Cohort 1, 20 (9.8%) were identified as positive for MRSA. Compared with residents identified as MRSA negative, a larger proportion of MRSA-positive residents had shorter periods of residence from the initial admission (median length of residence: 5.5 vs. 2.8 months), although this difference was not statistically significant (p = 0.084). Among 79 residents in Cohort 2, 60 (75.9%) were identified as MRSA negative at the initial testing. Of these 60 residents, only one (1.7%) had subsequent positive conversion in secondary MRSA testing. In contrast, among 19 residents identified as MRSA positive in the initial testing, 10 (52.6%) were negative in secondary testing.ConclusionsThe prevalence of MRSA was lower among residents with longer periods of LTCF residence than among those with shorter periods. Furthermore, few residents were found to become MRSA carrier after their initial admission. These findings highlight that MRSA in LTCFs might be associated with resident transfer rather than spread via cross-transmission inside LTCFs.

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

Liquid and Dry Swabs for Culture- and PCR-Based Detection of Colonization with Methicillin-Resistant Staphylococcus aureus during Admission Screening.

Rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) colonization status facilitates isolation and decolonization and reduces MRSA infections. Liquid but not dry swabs allow fully automated detection methods. However, the accuracy of culture and polymerase chain reaction (PCR) using liquid and dry swabs has not been analyzed. We compared different swab collection systems for routine nasal–throat MRSA screening in patients admitted to a tertiary care trauma center in Germany. Over 3 consecutive months, dry swabs (month 1), ESwabs (month 2), or MSwabs (month 3) were processed using Cepheid GeneXpert, Roche cobas and BD-MAX™ MRSA tests compared to chromogenic culture. Among 1680 subjects, the MRSA detection rate using PCR methods did not differ significantly between dry swabs, ESwab, and MSwab (6.0%, 6.2%, and 5.3%, respectively). Detection rates using chromogenic culture were 2.9%, 3.9%, and 1.9%, using dry, ESwab, and MSwab, respectively. Using chromogenic culture as the “gold standard”, negative predictive values for the PCR tests ranged from 99.2–100%, and positive predictive values from 33.3–54.8%. Thus, efficient and accurate MRSA screening can be achieved using dry, as well as liquid E- or MSwab, collection systems. Specimen collection using ESwab or MSwab facilitates efficient processing for chromogenic culture in full laboratory automation while also allowing molecular testing in automated PCR systems.

Take the initiative to reduce surgical site infections

Take the initiative to reduce surgical site infections

The Impact of Healthcare-Associated Methicillin-Resistant Staphylococcus aureus Infections on Postdischarge Health Care Costs and Utilization across Multiple Health Care Systems.

To measure how much of the postdischarge cost and utilization attributable to methicillin-resistant Staphylococcus aureus (MRSA) health care-associated infections (HAIs) occur within the US Department of Veterans Affairs (VA) system and how much occurs outside. Health care encounters from 3 different settings and payment models: (1) within the VA; (2) outside the VA but paid for by the VA (purchased care); and (3) outside the VA and paid for by Medicare. Historical cohort study using data from admissions to VA hospitals between 2007 and 2012. We assessed the impact of a positive MRSA test result on costs and utilization during the 365days following discharge using inverse probability of treatment weights to balance covariates. Among a cohort of 152,687 hospitalized Veterans, a positive MRSA test result was associated with an overall increase of 6.6 (95 percent CI: 5.7-7.5) inpatient days and $9,237 (95 percent CI: $8,211-$10,262) during the postdischarge period. VA inpatient admissions, Medicare reimbursements, and purchased care payments accounted for 60.6 percent, 22.5 percent, and 16.9 percent of these inpatient costs. While most of the excess postdischarge health care costs associated with MRSA HAIs occurred in the VA, non-VA costs make up an important subset of the overall burden.

Differences in Pre- and Post-dischcarge Methicillin-resistant Staphylococcus aureus (MRSA) infection rates by colonization status in US Department of Veterans Affairs (VA) hospitals

BackgroundLittle is known about how MRSA infection rates differ between patients who are colonized on admission compared with those who acquire colonization during an inpatient stay. In addition, most studies focus on MRSA infections that are diagnosed prior to discharge while ignoring those that are identified post-discharge. The VA implemented an active surveillance program for MRSA in 2007 in which all inpatients are tested for MRSA on admission. This surveillance data along with the ability to follow patients longitudinally allowed us to estimate the difference in infection rates for those who import vs. those who acquire MRSA colonization during their stay and to characterize post-discharge MRSA infections.MethodsWe constructed a dataset of 3,659,911 acute care inpatient admissions to 125 VA hospitals nationwide between January 1, 2008 and December 31/2015 who had surveillance tests performed for MRSA carriage. Admissions were restricted to individuals with at least 365 days of VA activity prior to admission. We categorized these admissions into 3 groups: no colonization, importation, and acquisition based on MRSA test results throughout the admission. We then captured MRSA infections in these individuals prior to discharge and at 30 and 90 days post-discharge. Infections were defined as positive MRSA cultures taken from sterile sites (including blood, catheter site, or bone).ResultsDuring the 8-year period, we identified 4,037 total pre-discharge MRSA infections, 2,793 MRSA infections at 30 days post-discharge, and 7,018 infections at 90 days post-discharge. During the pre-discharge time period, patients who acquired MRSA carriage were more likely to progress to an infection prior to discharge than those who imported the pathogen (RR = 2.6, P < 0.001). For patients who acquired MRSA carriage, the percentage who progressed to infection prior to discharge decreased from 2.0% in 2010 to 1.4% in 2015. The results from our analyses can be found in Figures 1–3.ConclusionWe found that roughly half of post-discharge infections were in patients who acquired the organism pre-discharge. These may be preventable with optimal infection control. In addition, there were nearly twice as many post-discharge MRSA infections at 90 days than during the pre-discharge period.Disclosures All authors: No reported disclosures.

Evaluation of the eazyplex MRSA assay for the rapid detection of Staphylococcus aureus in pleural and synovial fluid

Loop-mediated isothermal amplification (LAMP) is a simple and sensitive technique for rapid microbiological diagnosis. The aim of this study was to evaluate the analytical and diagnostic performance of the LAMP eazyplex MRSA test for the direct detection and differentiation of methicillin-susceptible (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) in synovial/pleural fluid. Analytical validation included the determination of the limit of detection (LoD) and analytical specificity of the eazyplex MRSA test. A diagnostic evaluation of the eazyplex test against bacterial culture was performed on routine pleural/synovial samples collected prospectively from patients aged less than 18 years with complicated pneumonia with empyema or arthritis admitted to the Children's Hospital Sant Joan de Déu in Barcelona, Spain, between April 2015 and May 2016. The new system appropriately detected a quality control panel of clinical samples with DNA of MSSA, MRSA, and other pathogens. The LoD was established at 6.4×103 CFU/ml for S. aureus and 1.0×104 CFU/ml for MRSA. Diagnostic validation of the eazyplex MRSA assay was performed on 51 prospective clinical invasive samples, resulting in sensitivity and specificity values of 83.3% and 97.8%, respectively, for S. aureus detection. The mean turnaround time was 70min. The eazyplex MRSA assay was found to be a useful test for the rapid detection of S. aureus in invasive samples such as pleural/synovial fluid.

Effect of the Methicillin-Resistant Staphylococcus aureus Nasal Polymerase Chain Reaction on Vancomycin Days and Clinical Outcomes in Pneumonia

BackgroundPrevious studies have demonstrated that the methicillin-resistant Staphylococcus aureus(MRSA) nasal polymerase chain reaction (PCR) assay has a high negative predictive value for MRSA pneumonia, and that a negative result may be used to guide antibiotic de-escalation. Despite increasing use in clinical practice, limited data exist regarding the impact of nasal MRSA testing on the duration of MRSA-directed therapy and patient outcomes. This study evaluated the effect of the MRSA nasal PCR result on vancomycin days and clinical outcomes in patients treated for pneumonia with empiric vancomycin therapy.MethodsA retrospective study of adult inpatients with an MRSA nasal PCR assay ordered between January 2015 and September 2015 was conducted. Patients with confirmed or presumed pneumonia and who were treated with empiric vancomycin therapy were included. Outcomes were compared for patients with a negative vs. a positive MRSA nasal PCR result. The primary outcome was the number of days of vancomycin therapy. Secondary outcomes included restart of vancomycin within 7 days, length of hospitalization, 30-day readmission, 30-day mortality, and predictive value of the MRSA PCR assay. Analyses were performed for the overall cohort and a propensity score-matched cohort.Results324 patients were included. In the overall cohort, the median duration of vancomycin therapy was 3 (interquartile range [IQR] 2–6) days in the negative MRSA nasal PCR group (n = 282) and 6 (IQR 4–9) days in the positive nasal PCR group (n = 42), P < 0.01. In the propensity score-matched cohort, the median number of vancomycin days was 3 (IQR 2–5) and 5 (IQR 4–8.5) in the negative (n = 137) and positive (n = 39) nasal PCR groups, respectively, P < 0.01. This difference persisted in an additional analysis of only patients with no positive respiratory cultures. No significant differences were observed in any secondary outcomes. The MRSA PCR assay demonstrated a positive predictive value of 45% and a negative predictive value of 98%.ConclusionA negative MRSA nasal PCR correlated with fewer days of vancomycin therapy without negatively impacting other clinical outcomes. The use of the MRSA nasal PCR assay may reduce the duration of MRSA-active therapy in PCR-negative patients.Disclosures All authors: No reported disclosures.

Isolation of Methicillin-resistant Staphylococcus aureus (MRSA) using a flocked swab elution transport system; with identification by PCR

Admission screening is an essential part of the control of methicillin-resistant Staphylococcus aureus (MRSA). Using collection systems that maintain viability and have high organism recovery, combined with accurate and rapid laboratory testing is critical for the success of a screening program. This review evaluates the performance of PCR testing, particularly the Roche LightCycler MRSA test, in the detection of MRSA. In addition, the clinical performance of the Copan Elution swab (ESwab) is reviewed. Several commercial molecular tests developed for use in detecting MRSA colonisation have been evaluated against culture methods, and all appear to provide high sensitivity, good specificity, and the potential for rapid reporting of MRSA colonisation. The new LightCycler MRSA advanced test is another of these assays with rapid detection time and high sensitivity. Compared with the BD GeneOhm MRSA assay, this new test also appears to have improved test specificity. The ESwab has an equal or even better recovery of bacteria, including MRSA, compared with other swab systems, via culture, and PCR. The advantages of using the ESwab are: the use of a liquid Amies medium allowed multiple uses (both culture, and PCR can be performed with one collected sample); and, specimens from multiple sites can be pooled into the same liquid transport media which limits the test costs and broadens the screening capabilities. However, there are limited publications on the clinical performance of the ESwab and more research is required on this new swab transport system.

LightCycler? MRSA Advanced Test for Rapid MRSA Detection in Referral Patients Admitted to Intensive Care Units

OBJECTIVE: We studied the prevalence of Methicillin Resistant Staphylococcus Aureus (MRSA) nasal carrier in patients who were transferred and admitted to the intensive care unit (ICU). MATERIALS AND METHOD: By using LightCycler® MRSA advanced test for the direct detection of MRSA DNA in nasal colonization by polymerase chain reaction (PCR) and comparing to standard MRSA isolated from plates culture media. RESULTS: From December 2010 to May 2011, 100 patients were enrolled. They were referred to be admitted in ICUs of Bangkok Hospital Medical Center (BMC) (87), Samitivej Hospital Sukhumvit (12) and Bangkok Hospital Pattaya (1). Seventeen patients were excluded from the study. Of 83 patients, the light cycler MRSA test detected MRSA from an anterior nasal swab in 12 (14.5%) patients while concomitant plates culture grew MRSA in 10 (12.1%) (Kappa = 0.7913, 95% condence interval (CI) = 0.594-0.988). CONCLUSION: The LightCycler® MRSA advanced test is a diagnostic test for rapid MRSA detection. The test aids in the detection of hospital infection and in the control of MRSA infections by rapid detection, therefore identifying the appropiate and isolated patient whom has MRSA colonization particularly in high risk patients.

Contemporary potencies of minocycline and tetracycline HCL tested against Gram-positive pathogens: SENTRY Program results using CLSI and EUCAST breakpoint criteria

Tetracycline class agents vary widely in their activity against emerging important antimicrobial-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter spp. Also, published susceptibility breakpoints are discordant between the Clinical and Laboratory Standards Institute (CLSI), the European Committee on Antimicrobial Susceptibility Testing (EUCAST), and regulatory-approved documents. We have assessed the impact of these differences for tetracycline HCL and minocycline when tested against contemporary Gram-positive pathogens. The SENTRY Antimicrobial Surveillance Program (2011) compared minocycline and tetracycline HCL activity via reference methods (M07-A9) using a worldwide collection of S. aureus (SA; 4917 strains with 1955 MRSA), Streptococcus pneumoniae (SPN; 1899), S. pyogenes (GRA; 246), and S. agalactiae (GRB; 217). Regardless of applied categorical breakpoints, minocycline exhibited wider coverage (% susceptible) than tetracycline HCL of 4.5–11.8/0.5–2.6/1.4–2.3/0.4–0.4% for MRSA/SPN/GRB/GRA, respectively. Lower EUCAST susceptible breakpoints produced reduced susceptibility rates for minocycline ranging from no difference (≤0.5 μg/mL) for GRA to −8.9% (≤1 μg/mL) for MRSA (97.2% susceptible by CLSI; 88.3% by EUCAST). Use of tetracycline HCL-susceptible results to predict minocycline susceptibility was very accurate (99.0–100.0%), with absolute categorical agreement rates ranging from 92.1% to 98.4% (CLSI) to 98.4% to 99.6% (EUCAST) for streptococci; greatest predictive error was noted using the CLSI breakpoints (14.7%) compared to EUCAST criteria (only 5.0%; acceptable), both for MRSA testing dominated by false-resistant results for minocycline. In conclusion, minocycline demonstrates continued superior in vitro activity compared to tetracycline HCL when testing SA (especially MRSA) and pathogenic streptococci. When testing tetracyclines, laboratories must recognize the expanded spectrum of minocycline against certain pathogens and utilize methods minimizing interpretive error. We conclude that EUCAST breakpoint criteria (≤0.5 or ≤1 μg/mL) represent the most conservative (better recognize strains with tet resistance mechanisms) and accurate tetracycline breakpoint guidelines for testing contemporary isolates of Gram-positive cocci.