Methicillin-resistant Staphylococcus Aureus Coverage 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.

Clinical utility of methicillin-resistant Staphylococcus aureus nasal PCR to streamline antimicrobial use in treatment of diabetic foot infection with or without osteomyelitis

BackgroundDiabetic Foot Infection (DFI) guidelines recommend empiric methicillin-resistant Staphylococcus aureus (MRSA)-targeted therapy in settings where there is high prevalence of MRSA infections or in cases of severe infection; however, they do not provide recommendations for de-escalation. This approach has the potential to increase unnecessary use of broad-spectrum antibiotics; therefore, additional strategies are needed to optimize appropriate antibiotic use. This study evaluates the effect of MRSA nasal PCR testing on MRSA-targeted antibiotic use and clinical outcomes in patients with DFI.MethodsThis was a retrospective quasi-experimental study of patients admitted to South Texas Veterans Health Care System for DFI, with or without osteomyelitis (OM), who had an MRSA nasal PCR and culture data. Eligible patients were identified from the Corporate Data Warehouse and reviewed via electronic health record. Patients were allocated into two groups: PRE (5/1/2019-4/30/2020) and POST (12/1/2020-11/30/2021) protocol implementation for de-escalation or avoidance of MRSA-targeted antibiotics. The primary outcome was median (interquartile range [IQR]) hours of empiric inpatient MRSA-targeted antibiotic therapy. A Wilcoxon Rank Sum test was used to assess the difference between the groups for the primary outcome. Secondary outcomes included the proportion of patients needing MRSA coverage added back for MRSA after de-escalation, hospital readmission, length of hospital stay (LOS), patient mortality, and acute kidney injury.ResultsA total of 151 patients were included (83 PRE; 68 POST). Most patients were male (98% PRE; 97% POST) with a median age of 64 (IQR, 56–72) years. Incidence of MRSA in DFI in the cohort was 14.7% overall (12% PRE and 17.6% POST). MRSA was detected via nasal PCR in 12% of patients 15.7% PRE and 7.4% POST). After protocol implementation, there was a significant decrease in empiric MRSA-targeted antibiotic therapy use, from a median of 72 (IQR, 27–120) hours in the PRE group, to 24 (IQR, 12–72) hours in the POST group (p < 0.01). No significant differences were found for other secondary outcomes.ConclusionThis study of patients presenting to a Veterans Affairs (VA) hospital with DFI identified a statistically significant decrease in median duration of MRSA-targeted antibiotic use post-protocol implementation. This suggests a favorable effect of MRSA nasal PCR for de-escalation or avoidance of MRSA-targeted antibiotics in DFI.

Current scenario of recently rising up cases of invasive group A streptococcal (iGAS) infections in younger children in many European nations: clinical management and prospective counteracting measures – an update

Current scenario of recently rising up cases of invasive group A streptococcal (iGAS) infections in younger children in many European nations: clinical management and prospective counteracting measures – an update

482: ROLE OF PNEUMONIA PCR PANEL ON METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS COVERAGE IN A TRAUMA ICU

Introduction: Pneumonia polymerase chain reaction (PCR) tests are a novel tool used to identify bacterial pathogens within hour(s) after sample collection versus up to 72 hours from a bronchoalveolar lavage (BAL). Early experience revealed a strong correlation between Staphylococcus aureus isolation and detection of resistance, and the trauma intensive care unit (TICU) adopted a protocol in September 2021 to escalate or de-escalate Methicillin-resistant Staphylococcus aureus (MRSA) coverage based on results. Methods: BioFire FilmArray pneumonia PCR panel assay results were evaluated in comparison to BAL culture results between September 2021 to March 2022 for patients admitted to the TICU of a large, academic, level 1 trauma center. Patients were categorized as early (< 5 days) or late (≥5 days) pneumonia in an ICU setting. The PCR panel assay was determined to correlate with the BAL if at least one organism identified in the PCR grew in the BAL. For patients treated for pneumonia, antibiotic regimens, antibiotic days, recurrence and clinical cure were evaluated and Fisher’s exact and Chi-square tests used for statistical analysis. Results: Pneumonia was suspected and PCR and BAL were obtained in 153 instances. Of those, 96 PCR panel assays detected bacteria (62.7%) with false negatives in 10/153 (6.5%) instances. Positive PCR panels correlated with BAL results in 52/96 (54.2%) of cases, with a positive predictive value (PPV) of 46.0%. 32 PCR assays detected S. aureus and 12 were detected in the corresponding BAL (PPV 37.4%). The presence or absence of methicillin-resistance correlated with cultures in all but one instance. Clinical outcomes were similar between groups for acute kidney injury, antibiotics days, MRSA days of coverage, recurrent pneumonia, and clinical cure. Conclusions: Pneumonia PCR panel assay demonstrated a 46% PPV with BAL culture results. The PCR assay demonstrates high sensitivity for S. aureus confirmed by BAL cultures and opportunities for de-escalation of MRSA coverage were identified in a majority of patients. Future educational efforts towards early antimicrobial streamlining may impact MRSA antibiotic duration, and larger sample sizes may reveal more correlation patterns.

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.

International Validation of a Methicillin-Resistant Staphylococcus aureus Risk Assessment Tool for Skin and Soft Tissue Infections.

To promote judicious prescribing of methicillin-resistant Staphylococcusaureus (MRSA)-active therapy for skin and soft tissue infections (SSTI), we previously developed an MRSA risk assessment tool. The objective of this study was to validate this risk assessment tool internationally. A multicenter, prospective cohort study of adults with purulent SSTI was performed at seven international sites from July 2016 to March 2018. Patient MRSA risk scores were computed as follows: MRSA infection/colonization history (2 points); previous hospitalization, previous antibiotics, chronic kidney disease, intravenous drug use, human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), diabetes with obesity (1 point each). Predictive performance of MRSA surveillance percentage, MRSA risk score, and estimated MRSA probability (surveillance percentage adjusted by risk score) were quantified using the area under the receiver operating characteristic curves (aROC) and compared. Performance characteristics of different risk score thresholds across varying baseline MRSA prevalence were examined. Two hundred three patients were included. Common SSTI were wounds (28.6%), abscess (25.1%), and cellulitis with abscess (20.7%). Patients with higher risk scores were more likely to have MRSA (P < 0.001). The MRSA risk score aROC (95%CI) [0.748 (0.678-0.819)] was significantly greater than MRSA surveillance percentage [0.646 (0.569-0.722)] (P = 0.016). Estimated MRSA probability aROC [0.781 (0.716-0.845)] was significantly greater than surveillance percentage (P < 0.001) but not the risk score (P = 0.192). The estimated negative predictive value (NPV) of an MRSA score ≥ 1 (i.e., a score of 0) was greater than 90% when MRSA prevalence was 30% or less. The MRSA risk score and estimated MRSA probability were significantly more predictive of MRSA compared with surveillance percentage. An MRSA risk score of zero had high predictive value and could help avoid unnecessary empiric MRSA coverage in low-acuity patients. Further study, including impact of such risk assessment tools on prescribing patterns and outcomes are required before implementation.

Profile of Antimicrobial Resistance and Sensitivity in Vulvar Abscesses in Women Attending a Tertiary Hospital

Context: Vulvar abscess is a highly prevalent pathology in patients seeking emergency care; however, its epidemiology has yet to be fully clarified. Aims: This study aimed to determine possible risk factors, the most common microorganisms involved and the appropriate antibiotic therapy in cases of vulvar abscesses treated in a tertiary hospital. Settings and Design: This prospective study included 51 women who presented with a vulvar abscess and sought medical help at the hospital’s gynaecological emergency room over a 70-week period. Methods: Drainage of the abscess and microbiological analysis allowed the pathogen responsible for the lesion to be identified, as well as the profile of antimicrobial sensitivity and resistance to be determined. Statistical analysis: Frequencies and percentages, as well as means, medians and standard deviations, were calculated. Associations between the study variables were determined using the chi-square test or Fisher’s exact test. Results: Overall, 52.94% of the cultures were positive for methicillin-resistant Staphylococcus aureus (MRSA). There was no significant difference in age between the patients infected with MRSA and those infected with other agents (p&gt;0.05). The MRSA isolates were sensitive to sulfamethoxazole + trimethoprim and to gentamicin, as were the great majority of the other pathogens. Shaving the vulvar region was the most important risk factor, being present in 74.5% of cases. Conclusion: MRSA is highly prevalent and a major cause of vulvar abscesses. Therefore, in these cases, an antibiotic therapy regimen with coverage for MRSA, such as sulfamethoxazole-trimethoprim, should be initiated as soon as possible.

Methicillin‐resistant Staphylococcus aureus among elderly patients with community-acquired pneumonia

IntroductionThe 2019 American Thoracic Society/Infectious Diseases Society of America guidelines for community-acquired pneumonia (CAP) recommend methicillin‐resistant Staphylococcus aureus (MRSA) coverage for patients with prior sputum isolation of MRSA. This study aimed to determine the impact of MRSA coverage on in-hospital mortality in elderly patients with CAP among whom MRSA was isolated. MethodsConsecutive elderly patients who were admitted for CAP and had positive sputum culture for MRSA were retrospectively included, and the association between MRSA coverage and in-hospital mortality was analyzed. ResultsTwenty (18%) of 111 patients received MRSA coverage. Although patients who received MRSA coverage tended to have more frequent prior isolation of MRSA compared to those who did not, no significant difference in in-hospital mortality was observed between both groups (2/20, 10% vs. 8/91, 9%). MRSA coverage was not associated with in-hospital mortality (odds ratio: 1.15; 95% CI: 0.23–5.89, p = 0.864); however, advanced age, hemoglobin level, a high A-DROP score, and C-reactive protein levels were associated with in-hospital mortality. MRSA coverage may not improve the prognosis of elderly patients with CAP who had positive sputum culture for MRSA. ConclusionsA randomized control study is required to determine the efficacy of MRSA coverage on the management of CAP in elderly patients.

Description and Characterization of Intraoperative Bacterial Cultures During Lung Transplant Surgery

<h3>Purpose</h3> Describe and characterize intraoperative bacterial cultures collected during lung transplant surgery. <h3>Methods</h3> This was a single-center retrospective chart review from 1/1/2018 through 5/31/2021. All adult patients undergoing lung transplant at Cedars Sinai Medical Center during the study period were included. No cystic fibrosis patients were transplanted during this time. Intraoperative cultures were collected by swabbing the bronchus. Given single and bilateral lung transplants were performed, a total of 84 patients yielded 116 cultures. The antibiotics utilized post-operatively were vancomycin and cefepime as per institutional protocol. Antibiotics were continued for at least 3 days until intraoperative cultures finalized. Further duration, consolidation, and/or de-escalation was based on clinical course and culture data. <h3>Results</h3> 56% (65/116) of cultures were positive for bacteria. Yearly breakdown yielded similar data: 53.3% (16/30) in 2018; 54.5% (12/22) in 2019; 66.7% (18/27) in 2020; 51.4% (19/37) in 2021. Forty-eight cultures had gram positive (GP) growth, with Staphylococcus being most common (42/48 of GP cultures). Methicillin-Resistant Staphylococcus Aureus (MRSA) accounted for 21.4% (9/42) of these cultures. Gram negative (GN) growth was seen in 38 cultures: Enterobacter (11/38), Klebsiella (10/38), Acinetobacter (7/38), Pseudomonas (4/38), Escherichia (2/38), Stenotrophomonas (1/38), Citrobacter (1/38), Neisseria (1/38), Haemophilus (1/38). <h3>Conclusion</h3> This culture data reinforces that broad spectrum antibiotics are warranted after lung transplant surgery. Given the high incidence of Staphylococcus, including MRSA, it is prudent to provide MRSA coverage until final culture data is available. Although Pseudomonas only accounted for 10.5% of GN cultures, this could be due to the patient population transplanted during the study period. Centers should continue to use their own culture data and population to guide antibiotic choice.

Inpatient outcomes for children receiving empiric methicillin‐resistant Staphylococcus aureus coverage for complicated pneumonia

AbstractRigorous evidence for antibiotic management of pediatric complicated pneumonia is lacking, likely contributing to variation in empiric antibiotic(s). Using the Pediatric Health Information System database, we sought to describe use and clinical outcomes of children hospitalized with complicated pneumonia who received empiric antibiotic regimens with and without methicillin‐resistant Staphylococcus aureus (MRSA) coverage. We evaluated empiric antibiotic selection on Day 0–1, grouping based on use of an antibiotic with or without MRSA coverage. We used generalized linear mixed effects models to examine the association of MRSA coverage and outcomes. Across 46 children's hospitals, 71.5% of children (N = 1279) received an empiric antibiotic regimen with MRSA coverage. In adjusted analyses, length of stay, need for repeat pleural drainage procedures, 7‐day emergency department revisits and 7‐day readmissions were similar between groups. Future prospective studies examining the need for MRSA coverage may assist in refining national treatment guidelines for complicated pneumonia in children.

169. Prevalence and Associated Patient Characteristics of Multi-Drug Resistant Organisms and Antibiotic Prescribing Patterns in Hospitalized Patients with Community-Acquired Pneumonia

BackgroundThe 2019 Infectious Diseases Society of America/American Thoracic Society community-acquired pneumonia (CAP) guidelines eliminated the term healthcare-associated pneumonia (HCAP), and recommends to guide the use of broad-spectrum antibiotics by locally validating the prevalence and risk factors of multi-drug resistant organisms (MDROs). The objective of this study is to determine the prevalence and associated patient characteristics of MDROs, and to characterize antibiotic prescribing patterns.MethodsThis was a retrospective, cohort study in adult patients hospitalized from 1/1/19 to 12/31/19. Patients were randomly selected from a patient list of diagnosis codes suggestive of pneumonia. We excluded patients with antibiotic therapy < 48 hours, bacterial co-infections from another site, or transferred from another hospital with length of stay >24 hours. Endpoints evaluated include the percentage of MDRO isolated from a respiratory or blood culture collected within 2 days of admission, comparison of patient characteristics associated with MDROs with those who did not, treatment regimen and duration, and rate of overtreatment and undertreatment. ResultsA total of 220 patients were included. Prevalence of overall MDRO, methicillin-resistant Staphylococcus aureus (MRSA), and Pseudomonas aeruginosa (PSA) was 8%, 3%, and 5%, respectively. Patient characteristics associated with MDROs from are shown in Table 1. Prior MDRO history or recent intravenous (IV) antibiotic exposure during hospitalization was present in 39% of the MDRO cohort. Over half (58%) of the patients were initiated on antibiotics with MRSA and/or PSA coverage. Rate of overtreatment and undertreatment was 89% and 5%, respectively. Mean antibiotic duration was 9 ± 3 days. ConclusionThe low prevalence of MDROs, coupled with the high overtreatment and low undertreatment rate suggests most patients hospitalized with CAP at our institution can receive an antibiotic regimen targeting standard CAP pathogens. Antibiotic stewardship intervention to shorten the duration of therapy should be considered. In addition to microbiology history and recent IV antibiotic exposure during hospitalization, further studies are needed to validate other patient characteristics at risk for MDROs.Disclosures All Authors: No reported disclosures

1301. Risk Factors for Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa in Community Acquired Pneumonia

Abstract Background The 2019 American Thoracic Society and Infectious Diseases Society of America Community-Acquired Pneumonia (CAP) guidelines concluded that the major risk factors for methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PsA) include prior isolation of these organisms and previous hospitalization with IV antibiotic use within 90 days. However, the guidelines recognized that results may vary by region and recommended local validation of risk factors. The primary objective of this study was to determine which potential risk factors are associated with MRSA and Pseudomonas aeruginosa in CAP in our institution. This study also evaluated appropriateness of antibiotics used for empiric CAP therapy. Methods This was a single-center, retrospective cohort study performed in an urban academic medical center in Cleveland, OH. Adults hospitalized for CAP who had a respiratory culture performed between January 2016 and September 2020 were included. Patients were randomized in a 1:1:1 ratio into MRSA, PsA, and non-resistant CAP (NR-CAP) groups. Patients with bacterial co-infections or resistant pathogens other than MRSA or PsA were excluded. Results The study included 111 patients with 37 patients in each group. The median age was 61 years (IQR 52-70), and 58.6% of patients were male. There were no independent risk factors for MRSA (Table 1). Independent risk factors for PsA included prior isolation and enteral feeding (Table 2). MRSA risk factors as defined by the 2019 CAP guidelines were found in 48.6% of patients with MRSA CAP (Figure 1). Guideline-defined PsA risk factors were found in 56.8% of patients with PsA CAP (Figure 2). In NR-CAP, 62.2% received empiric MRSA coverage while only 27% had a guideline-defined risk factor; PsA coverage was administered in 78.4% of NR-CAP patients, but risk factors were found in only 24.3% of this cohort. MRSA and P. aeruginosa Risk Factor Analyses Empiric MRSA and P. aeruginosa Coverage and Guideline-Defined Risk Factors Conclusion Our findings were consistent with the risk factors identified in the 2019 CAP guidelines, but additional risk factors may be present in our patient population. Empiric coverage for MRSA and PsA was disproportionately high relative to the rate of recovery. This study encourages local validation of risk factors; however, further analyses are needed to determine the impact on empiric therapy. Disclosures All Authors: No reported disclosures

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

Optimizing Treatment of Hand Infections: Is MRSA Coverage Always Necessary?

Background:Multiple publications have highlighted the prevalence of methicillin resistant Staphylococcus aureus (MRSA) as a cause of hand infections. We hypothesized that these publications have shifted the empiric treatment of hand infections. The aim of this study was to identify the current standard of care, the most common causative bacteria, and factors leading to extended length of stay for hand infection patients at a suburban hospital to improve treatment and establish an optimized care protocol.Methods:Retrospective cohort analysis was conducted to identify all patients admitted for hand infections over an 8-year period. A comprehensive chart review of each patient’s hospital course was completed.Results:A total of 70 patients were included. Maximum white blood cell count ≥ 12 was associated with a significantly longer hospital length of stay (9.1 days versus 5.4 days) compared to WBC values < 12 (P < 0.05). Also, 11 out of 23 (47.8%) underwent two or more incision and drainages (I&D’s), compared with patients with maximum WBC < 12. Vancomycin use as an empiric antibiotic was widespread (68 patients, 97.1%), despite only 14 (20%) having MRSA positive cultures. Univariate analysis identified a significant increased likelihood for increased length of stay (P < 0.05) and rise in creatinine (P < 0.05) in patients with an initial vancomycin trough level > 20.Conclusions:This analysis of hand infection treatment in a suburban hospital demonstrates the incidence of MRSA hand infections may not be universally high across institutions. Each hospital should review its own data to optimize hand infection treatment and its associated costs.

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.

1026. Is Empiric Coverage Necessary? Incidence of Pseudomonas aeruginosa and Methicillin-Resistant Staphylococcus aureus in Foot Infections

BackgroundEmpiric antibiotics for foot infections often include coverage of Pseudomonas aeruginosa (PA) and Methicillin-resistant Staphylococcus aureus (MRSA) due to their presumed frequency and ability to cause severe infection. The purpose of this study was to: 1) determine the incidence of PA and MRSA in foot infections; 2) identify variables associated with the presence of PA or MRSA; and 3) examine empiric antibiotic trends for foot infections to determine if empiric coverage of PA and MRSA is warranted.MethodsRetrospective study of foot infections at five large urban hospitals in San Diego during 2018. Data were collected from the medical records including demographics, host factors, laboratory data, pathology and imaging data, culture results, and empiric antibiotics. Patients with a foot infection treated as an inpatient in our healthcare system who had a culture collected were included.Results310 patients with foot infections were included. Mean age was 61.6 years; 220 (71%) were male; 248 (80%) had diabetes; 40 (13%) had end-stage renal disease (ESRD), and 122 (39%) had peripheral arterial disease (PAD). PA was present in 28 (9%) cases. No patient had a positive blood culture for PA. MRSA was present in 55 (18%) cases. Only one patient had a positive blood culture for MRSA. On univariate analysis, wound location not in the forefoot (p=0.047) and presence of PAD (p=0.048) were associated with PA. These failed to remain significant in multivariate analysis (OR=0.42, p=0.074 and OR=2.54, p=0.0504, respectively). Factors associated with MRSA included shallower depth of wound (OR=0.36; p=0.043). 199/310 patients (64%) received empiric antibiotic coverage for PA while 262/310 patients (85%) received empiric MRSA coverage. Of those who received empiric anti-PA coverage, 174 were overtreated (87%). Of those who received empiric anti-MRSA coverage, 218 (83%) were overtreated.ConclusionThe incidence of PA in foot infections was overall low, and none had positive blood cultures. MRSA was more often present, however, most patients did not have bacteremia or severe infections. In our study, the majority of empiric anti-PA, as well as anti-MRSA, antibiotic coverage for foot infections was unnecessary questioning the need for upfront, empiric coverage for these pathogens in foot infections.Disclosures All Authors: No reported disclosures

1471. Evaluation of Antibiotic De-escalation in Post Cardiac Arrest Patients with Culture-Negative versus Culture-Positive Aspiration Pneumonia

BackgroundCardiac arrest patients are often empirically treated for aspiration pneumonia with broad-spectrum antibiotics. Previous literature has shown no difference in clinical outcomes when discontinuing antimicrobial therapy for suspected aspiration pneumonia with negative respiratory cultures, but the application is limited in this population. This study aimed to assess antibiotic de-escalation practices for suspected aspiration pneumonia in post cardiac arrest patients with respiratory cultures and explore clinical outcomes.MethodsThis retrospective cohort conducted at a level 1 trauma center included adult out-of-hospital cardiac arrest patients who received antimicrobial therapy for suspected aspiration pneumonia. The primary endpoint was incidence of antibiotic de-escalation before day seven comparing culture-negative and culture-positive patients. De-escalation included discontinuation of methicillin-resistant Staphylococcus aureus (MRSA) coverage, Pseudomonas aeruginosa coverage, atypical coverage or all antibiotics when respective pathogens were not identified from microbiologic or serologic methods. Secondary endpoints included type of de-escalation and clinical outcomes.ResultsEighty-six patients were included: 45 culture-negative and 41 culture-positive. Figure 1 depicts the breakdown of organisms isolated. Guideline-directed empiric therapy was used in 18.6% of patients, with the remainder receiving excessively broad empiric coverage. Antibiotic de-escalation before day seven occurred in 28 (80%) culture-negative patients and 32 (82%) culture-positive patients (p = 0.82), excluding patients who died before day seven. Providers frequently stopped unnecessary MRSA coverage in both groups. In-hospital mortality was higher in the group of patients without antibacterial de-escalation (62% vs. 33%, p=0.03), but hospital length of stay, ICU length of stay, and number of ventilator-free days were not different between groups.Figure 1: Epidemiology of Pathogens Isolated From Respiratory Cultures in Cardiac Arrest Patients ConclusionCulture results were not associated with antibiotic de-escalation in post cardiac arrest patients with suspected aspiration pneumonia. Opportunities exist for further de-escalation in this population, particularly patients with unnecessary pseudomonal coverage.Disclosures All Authors: No reported disclosures

Trends and risk factors in the antibiotic management of skin and soft tissue infections in the United States

Objective The aim of this study was to examine the trends and risk factors of antibiotic treatment for skin and soft tissue infections (SSTIs), in the United States. Methods We conducted a retrospective analysis of SSTIs visits utilizing the 2011–2016 National Ambulatory Medical Care Survey. Results There were over 43 million visits for SSTIs in the US. We found no association between antibiotic treatment and gender, age, race, insurance, region, and metropolitan statistical area. Methicillin-resistant Staphylococcus aureus (MRSA) antibiotics were prescribed at 34.8% of SSTI visits, methicillin-sensitive Staphylococcus aureus (MSSA) antibiotics at 27.5%, and other antibiotics at 21.7%. Among visits treated with an antibiotic, 40.4% (n = 378) received an antibiotic with MSSA coverage, while 59.6% (n = 558) received an antibiotic with MRSA coverage. Region where the visit occurred was associated with the use of MSSA versus MRSA antibiotics (p = .013). Mean age of visits receiving MSSA antibiotics was significantly older than visits receiving MRSA antibiotics, 53.8 ± 1.2 vs. 50.9 ± 0.9 (p = .045). Conclusions This study found that providers more frequently utilize antibiotics with MRSA coverage for SSTIs. Antibiotic class chosen was associated with region, with MRSA coverage antibiotics more likely to be prescribed in the South. Additionally, individuals receiving antibiotics with MSSA coverage were older than those receiving antibiotics with MRSA coverage.

Correlation Between Patients With Methicillin-Resistant Staphylococcus aureus (MRSA) Nares Colonization and MRSA Diabetic Foot Infections.

Infectious Diseases Society of America diabetic foot infection (DFI) guidelines indicate empiric methicillin-resistant Staphylococcus aureus (MRSA) coverage for patients with a history of MRSA infection, when local prevalence of MRSA is high, or infection is clinically severe. These recommendations may lead to overutilization of empiric MRSA coverage, which can result in serious consequences. A strong negative predictive value (NPV) has been reported in literature for pneumonia, and recently, for all anatomical sites of infection. While these findings are promising, further validation is needed before clinicians may confidently use MRSA nares to guide empiric therapy for DFIs. A retrospective electronic medical record review was completed between October 1, 2013 and October 1, 2019. Patients met inclusion criteria if they were at least 18, admitted with a DFI, had MRSA nares test results, and DFI cultures. Patients were excluded if pregnant or MRSA infection within 1 year prior to index admission for DFI. A total of 200 patients met inclusion criteria. The majority of study participants were male with a mean age of 63. NPV of MRSA nares for MRSA DFIs was determined to be 94% and positive predictive value 58%. Sensitivity and specificity were 56% and 94%, respectively. Results of this study are consistent with prior literature supporting strong correlation of NPV for MRSA nares. The DFIs evaluated suggest a strong NPV of MRSA nares for MRSA DFIs, which may allow for faster de-escalation of empiric anti-MRSA antibiotic therapy and lower risk of adverse events associated with anti-MRSA therapy.

Postoperative Infections in Dermatologic Surgery: The Role of Wound Cultures.

Dermatologic surgery is associated with low postoperative infection rates, averaging from approximately 1% to 4.25%. Often, postoperative infections are treated empirically based on clinical diagnosis of infection, given it can take 48 to 72 hours for a wound culture to identify a pathogen. We aimed to evaluate the efficacy of empiric antibiotics in dermatologic surgery postoperative infections and if wound cultures change postoperative antibiotic therapy. A 7-center, retrospective analysis of postoperative infections, with culture data, in dermatologic surgery patients was performed. Of 91 cases of clinically diagnosed postoperative infection, 82.4% (n = 75) were successfully treated with empiric oral antibiotics (95% confidence interval [0.73-0.89], p < .0001). In 16 (17.6%) cases, initial empiric antibiotics were unsuccessful, and wound culture results altered antibiotic therapy in 9 cases (9.9%) with 6 (6.6%) of these cases requiring additional coverage for methicillin-resistant Staphylococcus aureus (MRSA). Empiric antibiotic treatment is usually appropriate for patients with postoperative surgical-site infections with wound cultures altering antibiotic management in a minority of cases. When empiric antibiotics fail, lack of MRSA coverage is usually the cause; therefore, providers should be aware of local MRSA prevalence and susceptibilities.