Risk Factors For Methicillin-resistant Staphylococcus Aureus Research Articles

297 Antibiotic prescribing for inpatients with community-acquired bacterial pneumonia (CABP) due to methicillin-resistant Staphylococcus aureus (MRSA) in the All of Us database: Are there differences by age, sex, race, and ethnicity?

OBJECTIVES/GOALS: The purpose of this work is to assess antibiotic prescribing for inpatients with community-acquired bacterial pneumonia (CABP) due to methicillin-resistant Staphylococcus aureus (MRSA) in the All of Us database. The goal of this research is to determine if different subgroups are more or less likely to receive anti-MRSA antibiotics. METHODS/STUDY POPULATION: This is a retrospective cohort study of inpatients with CABP due to MRSA from 2/1/2011 to 7/1/2022 in the All of Us database. Cases will be excluded for other treatment settings, other pathogens, and other types of pneumonia. Patients will be stratified by age, sex, race, and ethnicity. The proportion of patients who received anti-MRSA antibiotic therapy will be compared within groups with the chi-square statistic. Significant associations between patient characteristics and anti-MRSA prescribing (p < 0.05) will be assessed using multivariate logistic regression, with subgroup as the independent variable, anti-MRSA prescribing as the dependent variable, and divergent baseline characteristics as potential confounders. Odds ratios (OR) and 95% confidence intervals (95% CI) will be calculated. RESULTS/ANTICIPATED RESULTS: Previous research by our group has demonstrated differences in guideline-concordant, empiric antibiotic prescribing, for inpatients with CABP in the All of Us database; however, guideline-concordant empiric antibiotics for CABP do not routinely cover for MRSA. Anti-MRSA antibiotics are recommended if the patient has known MRSA or risk factors for MRSA. Investigations of disparity in anti-MRSA prescribing have been limited, especially since the abandonment of the healthcare-associated pneumonia (HCAP) categorization. Since the All of Us database contains information on CABP pathogens, we can study sub-types of CABP; therefore, we now hypothesize that the proportion of inpatients who received anti-MRSA antibiotics for CABP, due to MRSA, in the All of Us database, will differ by age, race, sex, and ethnicity. DISCUSSION/SIGNIFICANCE: This is one of the first studies to evaluate antibiotic prescribing for CABP due to MRSA in the All of Usdatabase. Identifying and understanding differences in care, such as possible discrepancies in anti-MRSA prescribing by age, sex, race, or ethnicity, is essential to develop targeted interventions to address disparities in health outcomes.

Predictors of hospital mortality and multidrug-resistant pathogens in hospitalized pneumonia patients residing in the community

Background and objectiveThe 2019 ATS/ADSA guidelines for adult community-acquired pneumonia (CAP) eliminated healthcare-associated pneumonia (HCAP) and considered it to be a form of CAP. This concept, however, was based on studies with relatively small sample sizes. MethodsWe investigated the risk factors of 30-day mortality, and methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa infections in patients with pneumonia coming from the community using the Diagnosis Procedure Combination database, a nationwide discharge database of acute care hospitals. Furthermore, we compared these factors between CAP and HCAP. ResultsA total of 272,337 patients aged ≥20 years with pneumonia were grouped into 145,082 CAP patients and 127,255 HCAP patients. The 30-day mortality rate (8.9 % vs.3.3 %), MRSA infection (2.4 % vs. 1.4 %), and Pseudomonas aeruginosa infection (1.6 % vs. 1.0 %) were significantly higher in HCAP than in CAP patients. Multivariable logistic regression analysis showed that 12 of 13 identified predictors of mortality (i.e., high age, male, underweight, non-ambulatory status, bedsore, dehydration, respiratory failure, consciousness disturbance, hypotension, admitted in critical care, comorbidity of heart failure, and chronic obstructive pulmonary disease) were identical in CAP and HCAP patients. Similarly, five of six distinct risk factors for MRSA infection, and three of three for Pseudomonas aeruginosa infection were identical between the patients. ConclusionThe risk factors for mortality and MRSA or Pseudomonas aeruginosa infection were almost identical in patients with CAP and HCAP. The assessment of individual risk factors for mortality and MRSA or Pseudomonas aeruginosa infection in CAP and abandoning categorization as HCAP can improve and simplify empiric therapy.

Fear of missing organisms (FOMO): Diabetic foot and osteomyelitis management opportunities

Background: Hospitalizations for diabetic foot infections and lower-extremity osteomyelitis are common. Use of empiric antibiotic therapy for methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa is also common. Guidelines recommend antibiotic therapy based on severity of illness, risk factors for MRSA and P. aeruginosa, and local prevalence. We evaluated the concordance between empiric antibiotic therapy and both culture results and definitive antibiotic therapy with a focus on MRSA and P. aeruginosa. We also evaluated how well MRSA and pseudomonal risk factors were predictive of culture results with these organisms. Methods: We conducted a cohort study of all patients admitted to our hospital system in 2021 with a diagnosis of a diabetic foot infection or lower-extremity osteomyelitis. Patients were included if they had an International Classification of Disease, Tenth Revision (ICD-10) diagnosis code of M86, E10.621, E11.621, or E08.621. Patients were excluded if antibiotics were for another indication or if they were aged <18 years. In patients with multiple hospitalizations only the first hospitalization was included. Empiric antibiotic therapy included antibiotics started by the admitting team. Definitive antibiotic therapy included the final antibiotic course either completed during admission or prescribed at the time of discharge. MRSA risk factors included prior positive culture with MRSA within the last year, hospitalization with IV antibiotics within 90 days, intravenous drug use, or hemodialysis. Pseudomonal risk factors included prior positive culture with P. aeruginosa within the last year or hospitalization with IV antibiotics within 90 days. Results: In 2021, 260 unique patients were admitted with suspected diabetic foot infections or lower-extremity osteomyelitis. 68 patients had >1 admission. Empiric anti-MRSA and antipseudomonal therapy was administered to 224 (86%) and 214 (82%) patients, respectively. Definitive anti-MRSA and antipseudomonal therapy was administered to 76 (30%) and 51 (20%) patients, respectively. Of the 195 patients who had wound cultures, 29 (15%) and 18 (9%) had positive cultures for MRSA and P. aeruginosa respectively (Fig.). The negative predictive value of MRSA risk factors for predicting a negative culture with MRSA was 91%. The negative predictive value of pseudomonal risk factors for predicting a negative culture with P. aeruginosa was 95%. Conclusions: Our data suggest an opportunity for substantial reductions in empiric anti-MRSA and antipseudomonal therapy for diabetic foot infection and lower-extremity osteomyelitis. The absence of MRSA and pseudomonal risk factors was reasonably good at predicting the absence of a positive culture with these organisms.Disclosure: None

Bacterial Genotype, Carrier Risk Factors, and an Antimicrobial Stewardship Approach Relevant to Methicillin-resistant Staphylococcus aureus Prevalence in a Population of Macaques Housed in a Research Facility.

Methicillin-resistant Staphylococcus aureus (MRSA) remains a significant problem for human and animal health and can negatively affect the health status of macaques and other nonhuman primates (NHP) in research colonies. However, few publications provide guidance on the prevalence, genotype, or risk factors for macaques with MRSA and even fewer on how to effectively respond to MRSA once identified in a population. After having a clinical case of MRSA in a rhesus macaque, we sought to determine the MRSA carrier prevalence, risk factors, and genotypes of MRSA in a population of research NHPs. Over a 6-wk period in 2015, we collected nasal swabs from 298 NHPs. MRSA was isolated from 28% (n = 83). We then reviewed each macaque's medical record for a variety of variables including animal housing room, sex, age, number of antibiotic courses, number of surgical interventions, and SIV status. Analysis of these data suggests that MRSA carriage is associated with the room location, age of the animal, SIV status, and the number of antibiotic courses. We used multilocus sequence typing and spa typing on a subset of MRSA and MSSA isolates to determine whether the MRSA present in NHPs was comparable with common human strains. Two MRSA sequence types were predominant: ST188 and a novel MRSA genotype, neither of which is a common human isolate in the United States. We subsequently implemented antimicrobial stewardship practices (significantly reducing antimicrobial use) and then resampled the colony in 2018 and found that MRSA carriage had fallen to 9% (26/285). These data suggest that, as in humans, macaques may have a high carrier status of MRSA despite low clinically apparent disease. Implementing strategic antimicrobial stewardship practices resulted in a marked reduction in MRSA carriage in the NHP colony, highlighting the importance of limiting antimicrobial use when possible.

Reduction in the prevalence of methicillin-resistant Staphylococcus aureus in tissue and wound swab samples taken from outpatients attending a specialist diabetic foot clinic 2005-2021.

To assess annual change in prevalence of methicillin resistant Staphylococcus aureus (MRSA) from tissue and wound swab samples from foot ulcers (DFUs) in people with diabetes between 2005 and 2021. A retrospective analysis of everyone with MRSA positive wound or tissue swabs taken from our specialist multidisciplinary foot clinic between July 2005 and July 2021. A total of 406 MRSA positive isolates from DFU swabs were identified from 185 individuals attending the foot clinic. There were 22 hospital-acquired infections (HAIs) and 159 community-acquired infections (CAIs). Fifty-two per cent (n= 37) of these individuals from 2010 to 2021 (n= 71) had presence of at least three risk factors for MRSA. The total number of swabs sent was 6312 from 1916 individuals living with diabetes. Annual MRSA DFU prevalence peaked in 2008 at 14.6% (n= 38), decreased in 2013 to 5.2% (n= 20) and did not exceed 4% (n= 6) from 2015 to 2021. Hospital MRSA was lowest in 2021 (n= 211), a 76% fall from 2007 (n= 880). Incidence of MRSA HAI from 2015 to 2021 ranged from 5.4% (n= 14) in 2020 to 11.5% (n= 41) in 2018. Prevalence of MRSA in DFU infections treated as outpatients is decreasing in line with falls in hospital acquired blood-borne infections and with overall hospital MRSA incidence. This is likely a reflection of the combination of interventions, including stringent antibiotic prescribing and decolonisation strategies. Reduction in prevalence should have positive impact on outcomes in people living with diabetes, reducing the complication of osteomyelitis and necessity for long-term antibiotic administration.

Fear of Missing Organisms (FOMO): the discordance among broad-spectrum empiric antibiotic therapy, microbiologic results, and definitive antibiotic therapy for diabetic foot infections and lower extremity osteomyelitis.

Empiric broad-spectrum antibiotic therapy is commonly prescribed for patients hospitalized with diabetic foot infections (DFI) and lower extremity osteomyelitis (OM). The primary objective was to evaluate the concordance between empiric antibiotic therapy, microbiologic results, and definitive antibiotic therapy with a focus on methicillin-resistant Staphylococcus aureus (MRSA) and resistant gram-negative organisms. The secondary objective was to evaluate the negative predictive values (NPV) of select risk factors for MRSA and resistant gram-negative organisms for microbiologic results with these organisms. Retrospective cohort study. Safety-net health system in Ohio. Adults hospitalized and receiving antibiotic therapy for DFI or lower extremity OM in 2021. For 259 unique patients, empiric therapies with activity against MRSA and resistant gram-negative organisms were administered to 224 (86.5%) and 217 (83.8%) patients, respectively. Definitive therapies with activity against MRSA and resistant gram-negative organisms were administered to 91 (35%) and 74 (28.6%) patients, respectively. Of 234 patients with microbiologic testing, 29 (12.4%) had positive cultures with MRSA and 41 (17.5%) with resistant gram-negative organisms. The NPVs of risk factors for MRSA and resistant gram-negative organisms for the absence of these organisms in culture were 91% and 85%, respectively. For patients hospitalized with DFI and lower extremity OM, our data suggest opportunities for substantial reductions in empiric therapies with activity against MRSA and resistant gram-negative organisms. The absence of risk factors for these organisms was reasonably good at predicting negative cultures with these organisms.

The Potential Threat of Vertical Transmission in Methicillin-Resistant Staphylococcus Aureus Infection: A Systematic Review 2022.

This systematic review paper aimed to assess and analyze the prevalence of maternal colonization of Staphylococcus aureus (S. aureus) also known as methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) in the peripartum period and its significance on vertical transmission to the neonate and if it is a potential threat to the health of newborns. For this, multiple databases, such as PubMed, MEDLINE, ScienceDirect, and the database of Elsevier, were used to scout for relevant articles, and results were reported adhering to the principles set by Preferred Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines 2020. A specific medical subject headings (MeSH) criterion was designed to search for relevant publications on PubMed. A total of 26 articles were finally selected after a meticulous screening process, including detailed inclusion and exclusion criteria, manual reading of titles and abstracts, and availability of accessible full-text articles. A few articles were also selected after going through the citations section of the initially selected papers. Quality appraisal was done on the selected publications. Maternal colonization of S. aureus is determined to be highly prevalentwith the hypothesis that nasal colonization had higher rates than recto-vaginal sites. Increasing maternal age, history of vaginitis, and multiparity were the most common risk factors for MRSA and MSSA colonization. Premature babies were at the highest risk of MRSA colonization. Breast milk is also a risk factor for neonatal MRSA transmission. Through this systematic review, we concluded that although the rate of vertical transmission of MRSA is lower than that of MSSA, we felt that it held significance as neonates with the bug have poor outcomes due to skin and soft tissue infections and there is spread of MRSA to other neonates in the wardsand spread to siblings in cases of triplets and quadruplets and even death due to potential MRSA sepsis. Women in Africa and China had high prevalence rates of MRSA and S. aureus which can probably be attributed to a lack of access to adequate healthcare facilities. We recommend screening with regular recto-vaginal swabs and nasal swabs especially in regions with a high burden of MRSA to be performed at regular intervals after confirmation of pregnancy, as prevention and screening are effective to avoid serious complications.

Clinical characteristics and factors related to infection with SCCmec type II and IV Methicillin-resistant Staphylococcus aureus in a Japanese secondary care facility: a single-center retrospective study

ObjectivesDifferences in virulence genes, including psm-mec, which is a phenol-soluble modulin-mec (PSM-mec) encoding gene, of predominant staphylococcal cassette chromosome mec (SCCmec) types II and IV Methicillin-resistant Staphylococcus aureus (MRSA) may contribute to the virulence and clinical features of MRSA in Japan. We aimed to clarify the clinical characteristics and risk factors of infection among SCCmec types II and IV MRSA isolates from a Japanese secondary acute care hospital. MethodsWe analysed 58 SCCmec type II and 83 SCCmec type IV MRSA isolates collected from blood, central venous catheter tips, deep or superficial tissues, and sputum. ResultsSCCmec type II MRSA risk factors for progression to infection were seb, enterotoxin gene cluster, psm-mec mutation, and vancomycin minimum inhibitory concentrations (MIC) of 1 or 2 mg/L as virulence factors (adjusted odds ratio [aOR] = 11.8; 95% confidence interval [CI]: 2.49–77.7; P = 0.004); solid tumour was a host factor (aOR = 25.9; 95% CI: 3.66–300; P = 0.003). SCCmec type IV MRSA risk factors were sea, cna, and vancomycin MIC of 1 or 2 mg/L as virulence factors (aOR = 3.14; 95% CI: 1.06–10.6; P = 0.049) and intravascular indwelling catheter as host factors (aOR = 3.78; 95% CI: 1.03–14.5; P = 0.045). Compared with SCCmec type II, SCCmec type IV MRSA resulted in more frequent bloodstream infections and higher Sequential Organ Failure Assessment scores. ConclusionWe found that factors related to virulence genes and bacteriological and host characteristics are associated with SCCmec types II and IV MRSA infection and severity. These risk factors may be useful criteria for designing infection control programs.

A Retrospective Study of the Overuse of Extended-Spectrum Antibiotics in Patients With Community-Acquired Pneumonia With Risk for Methicillin-Resistant Staphylococcus aureus and/or Pseudomonas aeruginosa.

Background The changing epidemiology of pneumonia is due to aging hosts and the emergence of new pathogens that requireongoing evaluation and updates on antibiotic treatment. Guidelines from the 2019 Infectious Diseases of American Society/American Thoracic Society (IDSA/ATS) provide recommendations for the treatment and management of community-acquired pneumonia (CAP) with risk for methicillin-resistant Staphylococcus aureus (MRSA) and/or Pseudomonas aeruginosa. The objective of this research is to examine patients with CAP with riskfor MSRA and/or Pseudomonas aeruginosa to assess the overuse of extended-spectrum antibiotics. Methods A retrospective study using a convenience sample of medical records from 118 adult patients with CAP with risk factors for MRSA and/or Pseudomonas was completed from August to December 2019. Descriptive analyses were employed to compute the number and percentages of demographic variables (age, gender), overuse of antibiotics, duration of treatment, and risk factors. Results Of 118 patients, 59.3% were males and 77.9% were aged 60 years and older. Seventy-four percent (74%) of patients were prescribed extended-spectrum antibiotics. Most patients(42%) were treated with extended-spectrum antibiotics and did not meet the risk factors based on the 2019 IDSA/ATS recommended guidelines. Twenty percent (20%) were prescribed antibiotics for eight days or more. Patients with known risk factors, including low positive blood (5%) and respiratory (26%) cultures, antibiotic use (25%), and admission to the hospital within 90 days (30%) were identified. Conclusion In this sample, the overuse of antibiotics was high. The significant percentage of patients that were over-treated with extended-spectrum antibiotics could lead to adverse outcomes.

New testing guidelines for community-acquired pneumonia.

The purpose of this article is to review diagnostic testing recommendations outlined in the current American Thoracic Society (ATS)/Infectious Diseases Society of America (IDSA) community-acquired pneumonia (CAP) guideline and the 2021 ATS guideline for noninfluenza respiratory viruses. Diagnostic testing in CAP with gram stain, lower respiratory and blood cultures, Streptococcal and Legionella urinary antigens are not routinely recommended unless identified as severe CAP or with risk factors for Methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa infection. Influenza virus testing remains a strong recommendation during periods of community viral spread.An additional 2021 ATS clinical practice guideline reviewed the use of molecular testing for noninfluenza viral pathogens in adults with suspected CAP and recommended testing in those hospitalized with severe CAP and/or various immunocompromising conditions. Diagnostic testing remains an important component of confirming and treating CAP. The CAP guideline includes recommendations surrounding diagnostic testing with lower respiratory gram stain and culture, blood cultures, Legionella and Pneumococcal urinary antigen, influenza viral testing and serum procalcitonin.There is a strong recommendation to obtain influenza virus testing during periods of community spread. However, the use of other diagnostics such as gram stain, lower respiratory and blood culture, and urinary antigen testing are dependent on severity of illness and whether a patient has been identified as having strong risk factors for MRSA or P. aeruginosa infection. The 2021 ATS clinical practice document did not routinely recommend testing noninfluenza respiratory viruses unless identified as having severe CAP and/or various immunocompromising conditions.

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

Empiric Vancomycin Reduction in a Pediatric Intensive Care Unit.

At our institution, empirical vancomycin is overused in children with suspected bacterial community-acquired infections (CAIs) admitted to the PICU because of high community rates of methicillin-resistant Staphylococcus aureus (MRSA). Our goal was to reduce unnecessary vancomycin use for CAIs in the PICU. Empirical PICU vancomycin indications for suspected CAIs were developed by using epidemiological risk factors for MRSA. We aimed to reduce empirical PICU vancomycin use in CAIs by 30%. After retrospectively testing, the indications were implemented and monthly PICU empirical vancomycin use during baseline (May 2017-April 2018) and postintervention (May 2018-July 2019) periods. Education was provided to PICU providers, vancomycin indications were posted, and the antibiotic order set was revised. Statistical process control methods tracked improvement over time. Proven S aureus infections for which vancomycin was not empirically prescribed and linezolid or clindamycin use were balancing measures. We identified 1620 PICU patients with suspected bacterial CAIs. Empirical vancomycin decreased from a baseline of 73% to 45%, a 38% relative reduction. No patient not prescribed empirical vancomycin later required the addition of vancomycin or other MRSA-targeted antibiotics. There was no change in nephrotoxicity or in the balancing measures. Development of clear and concise recommendations, combined with clinician education and decision support via an order set, was an effective and safe strategy to reduce PICU vancomycin use. Retrospective validation of the recommendations with local data were key to obtaining PICU clinician buy in.

The burden of methicillin-resistant Staphylococcus aureus in the delivery of eye care.

BackgroundTo describe the clinical presentation, burden and antimicrobial resistance of Methicillin-Resistant Staphylococcus aureus (MRSA) eye infections and to recommend a streamlined protocol for the management of ocular MRSA colonisation detected by pre-operative screening.MethodsA retrospective review of all ocular samples which resulted in the isolation of MRSA between 1st of January 2013 and 31st of December 2019 at the Royal Victoria Eye and Ear Hospital.ResultsA total of 185 samples taken from the ocular surface were MRSA positive. The majority were MRSA colonisation of the ocular surface obtained as part of an MRSA screen (139/6955 patients screened; 2%). Forty-six represented MRSA infections (46/7904 eye samples; 0.58%), most occurring in older patients the majority of whom had known local or systemic risk factors for colonisation. The most common presentation was conjunctivitis (n = 24), followed by pre-septal cellulitis (n = 9). MRSA infections with the poorest clinical outcomes and the longest inpatient stay, were keratitis (n = 6) and post-operative endophthalmitis (n = 2). Our study demonstrated over 60% resistance to azithromycin, fusidic acid and ciprofloxacin, although resistance to chloramphenicol was uncommon.ConclusionThis study demonstrates that MRSA infections of the eye most commonly manifest as a mild infection, typically conjunctivitis, and are generally non-sight threatening. The majority of presentations occur in the context of known MRSA risk factors and in an older populous. Resistance to chloramphenicol is rare, thus it remains an excellent first line treatment. Its use to eradicate MRSA from the ocular surface is proposed to streamline the delivery of surgical eye care.

Methicillin-Resistant Staphylococcus Aureus Bacteremia: Epidemiology, Clinical Characteristics, Risk Factors, and Outcomes in a Tertiary Care Center in Riyadh, Saudi Arabia.

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) has become increasingly common in hospitals worldwide. In an era of pandemics, it is important to understand all types of infectious diseases in order to control its outcome and reduce mortality rates related to it. This study aims to identify the epidemiology of MRSA bloodstream infection, risk factors, and mortality in King Abdulaziz Medical City in Riyadh.MethodsThis is a retrospective chart review study from January 2013 to June 2017. All patients with positive blood culture for MRSA at King Abdulaziz Medical City (KAMC), which is a tertiary care center in Riyadh, Saudi Arabia, were included. Data were extracted from electronic and paper medical records for patients who had a positive blood culture for MRSA. Data collected included demographics, microbiological details, risk factors, and 30-day mortality.ResultsFrom 2013 through June 2017, 633 Staphylococcus aureus bacteremia were reported in KAMC, of which 184 (29.1%) were MRSA with a mean age of 60±19 years. Almost all of our isolates were susceptible to vancomycin, linezolid, and tigecycline. The most common infectious syndrome these patients presented with was an endovascular infection which accounts for 30.4% while 19.9% presented as a case of pneumonia. The mortality within 30 days of collection of the positive blood culture was 20.65%. Male gender (OR = 2.33; 95% CI = 1.34-4.05; P-value = 0.003) and patients with history of recent hospital (OR = 2.34; 95% CI = 1.27-4.34; P-value = 0.007) or ICU (OR = 1.66; 95% CI = 1.09-2.52; P-value = 0.018) admissions were more likely to acquire MRSA.ConclusionsThe incidence of MRSA bacteremia at King Abdulaziz Medical City is high and increasing in conjunction with incidence rate posing a significantly high rate of mortality. Recent history of hospital admission, ICU admission and males were found to be significantly associated with higher rates of MRSA infection. Some modifiable risk factors that could be used to facilitate the reduction of MRSA acquisition rates is to avoid unnecessary hospital and ICU admissions.

Validation of Methicillin-Resistant Staphylococcus aureus (MRSA) Risk Factors in Predicting MRSA Community-Acquired Pneumonia at an Academic Medical Center.

Background: The 2019 Infectious Diseases Society of America community-acquired pneumonia (CAP) guidelines recommend antimethicillin- resistant Staphylococcus aureus (MRSA) therapy in patients with CAP based on previously identified risk factors for MRSA with an emphasis on local epidemiology and institutional validation of risk. Thus, we sought to assess the ability of guideline-recognized risk factors to predict MRSA CAP at our institution. Methods: This was a single-center, retrospective cohort study from January 2016 to March 2020. Patients were included if they were >18 years old, diagnosed with CAP, and had a MRSA nasal screen and respiratory culture obtained on admission. Patients were excluded if CAP diagnosis was not met, respiratory cultures were not obtained within 48 hours of antibiotic initiation, or they had cystic fibrosis. Sensitivity, specificity, negative predictive value, positive predictive value, and likelihood ratios (LR) were calculated using Vasser Stats 2019. Pre/post-test odds and pre/post-test probabilities were calculated using Excel 2019. Results: Of 705 screened patients, 221 were included. MRSA prevalence in CAP patients at our institution was 3.6%. History of MRSA isolated from a respiratory specimen had high specificity (98%), high positive LR of 20 (95% CI 5.3-74.8), and high post-test probability of 42.8%. Receipt of IV antibiotics during hospitalization within the past 90 days had a positive LR of 1.9 (95% CI 0.74-4.84). A positive MRSA nasal screen on admission had a positive LR of 6.9 (95% CI 4.0-12.1), negative LR 0.28 (95% CI 0.08-0.93), positive post-test probability of 20.7%, and negative post-test probability of 1.04%. Conclusion: Our study utilized institutional data to validate guideline recognized risk factors for MRSA CAP specifically at our institution. Risk factors including history of MRSA isolated from a respiratory specimen, and positive post-admission MRSA nasal screen were validated as significant risk factors; receipt of IV antibiotics during hospitalization within the past 90 days was not shown to be a risk factor for MRSA CAP based on our institutional data. Validated risk factors may help providers discern which patients with CAP at our institution would benefit most from empiric MRSA treatment.

What is the most cost\u2010effective strategy for nasal screening and Staphylococcus aureus decolonization in patients undergoing total hip arthroplasty?

BackgroundTo reduce periprosthetic joint infection after total hip arthroplasty (THA), several nasal screening and decolonization strategies for methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) have been performed. These include universal decolonization (UD; i.e., no screening and decolonization for all patients), universal screening and target decolonization (US; i.e., screening for all patients and decolonization for bacterial positive patients), and target screening and decolonization (TS; i.e., screening and decolonization for high-risk populations only). Although TS is the most cost-effective strategy, useful risk factors must be identified. The purpose of this study was to evaluate the presence of predictive factors that enable the TS strategy to be successfully implemented and to compare the costs of each strategy.MethodsA total of 1654 patients scheduled for primary or revision THA (1464 female, 190 male; mean age 64 years) were screened prior to surgery for bacterial colonization of the nasal mucosa. Risk factors for positive MRSA and S. aureus (including both MRSA and MSSA) tests were analyzed according to the following parameters: sex, age ≥ 80 years, body mass index ≥ 30 kg/m2, antibiotic use within 3 years, corticosteroid use, serum albumin < 3.5 g/dL, glomerular filtration rate < 50 mL/min, presence of brain, thyroid, cardiac, or pulmonary disease, diabetes, asthma, smoking status, and whether revision surgery was performed. The average cost of each strategy was calculated.ResultsIn total, 29 patients (1.8 %) tested positive for MRSA and 445 (26.9 %) tested positive for S. aureus. No parameters were identified as independent risk factors for MRSA and only female sex was identified as a risk factor for S. aureus (p = 0.003; odds ratio: 1.790; 95 % confidence interval: 1.210–2.640). The average cost of each strategy was 1928.3 yen for UD, 717.6 yen for US, and 717.6 yen for TS (for eradicating MRSA), and 1928.3 yen for UD, 1201.6 yen for US, and 1160.4 yen for TS (for eradicating S. aureus).ConclusionsNo useful predictive parameters for implementing the TS strategy were identified. Based on cost implications, US is the most cost-effective strategy for THA patients.

Methicillin-resistant Staphylococcus aureus in hip fracture.

Infection after surgery increases treatment costs and is associated with increased mortality. Hip fracture patients have historically had high rates of methicillin-resistant Staphylococcus aureus (MRSA) colonization and surgical site infection (SSI). This paper reports the impact of routine MRSA screening and the "cleanyourhands" campaign on rates of MRSA SSI and patient outcome. A total of 13,503 patients who presented with a hip fracture over 17 years formed the study population. Multivariable logistic regression was performed to determine risk factors for MRSA and SSI. Autoregressive integrated moving average (ARIMA) modelling adjusted for temporal trends in rates of MRSA. Kaplan-Meier estimators were generated to assess for changes in mortality. In all, 6,189 patients were identified before the introduction of screening and 7,314 in the post-screening cohort. MRSA infection fell from 69 cases to 15 in the post-screening cohort (p < 0.001). The ARIMA confirmed a significant reduction in MRSA SSI post-screening (p = 0.043) but no significant impact after hand hygiene alone (p = 0.121). Overall SSI fell (2.4% to 1.5%), however deep infection increased slightly (0.89% to 1.06%). ARIMA showed neither intervention affected overall SSI ("cleanyourhands" -0.172% (95% confidence interval (CI) -0.39% to 0.21); p = 0.122, screening -0.113% per year, (95% CI -0.34 to 0.12); p = 0.373). One-year mortality after deep SSI was unchanged after screening (50% vs 45%; p = 0.415). Only warfarinization (OR 3.616 (95% CI 1.366 to 9.569); p = 0.010) and screening (OR 0.189 (95% CI 0.086 to 0.414); p < 0.001) were significant covariables for developing MRSA SSI. While screening and decolonization may reduce MRSA-associated SSI, the benefit to patient outcome remains unclear. Overall deep SSI remains an unsolved problem that has seen little improvement over time. Preventing other hospital-associated infections should not be forgotten in the fight against MRSA. Cite this article: Bone Joint J 2021;103-B(1):170-177.

227. Evaluation of Empiric Vancomycin Utilization at 72 Hours Post Admission: is De-escalation of Vancomycin Appropriate?

BackgroundAt both of our institutions in 2018, the average vancomycin days of therapy per 1,000 patient days was 112. The purpose of this study was to examine a 72-hour time-out as an effective de-escalation tool by evaluating the indication and clinical appropriateness of the continuation of empiric vancomycin therapy.MethodsA retrospective chart review was performed from January 2018 to October 2018 at two community hospitals. Patients > 18 years who received at least 3 days of empiric vancomycin therapy were included. Patients were excluded if immunocompromised, pregnant, on hemodialysis, received vancomycin for surgical prophylaxis, or expired within 72 hours of vancomycin initiation. Criteria for appropriate continuation of vancomycin at 3 days: positive culture for methicillin-resistant Staphylococcus aureus (MRSA), presence of infection with or without defined sources with systemic signs of infection (i.e. white blood cells >12,000 cells/L or < 5,000 cells/L and/or elevated temperature ≥ 37.5°C), or pending wound/sputum cultures after vancomycin initiation.ResultsA total of 160 adult patients initiated on vancomycin were analyzed; 118 of 160 (74%) met appropriate criteria. The most common indications for vancomycin were: skin and soft tissue infections (SSTI) 82 patients (51%); pneumonia 37 patients (23%); and positive blood culture 20 patients (13%). Risk factors for MRSA were similar between both groups. Forty-four (28%) patients had cultures pending and 23 patients (14%) had a known non-MRSA pathogen at time of assessment. American Indian race (OR 3.01 (1.21, 7.53) p-value= 0.0174) and SSTI indication (OR 2.87 (1.24, 6.80) p-value= 0.0147) were associated with not meeting appropriate criteria. ConclusionApproximately 25% of patients receiving empiric vancomycin therapy did not meet clinical criteria for continuation beyond 72 hours. The indication most commonly associated with continued vancomycin utilization was SSTI. These results identified indications in which empiric vancomycin prescribing can be optimized, and a 72-hour antibiotic time-out may be warranted as a stewardship intervention. Timely culture obtainment and intervention when another pathogen is identified are possible strategies to ensure success of 72-hour time-out.Disclosures All Authors: No reported disclosures

Risk Factor Evaluation for Methicillin-Resistant Staphylococcus aureus and Pseudomonas aeruginosa in Community-Acquired Pneumonia.

The 2019 community-acquired pneumonia guidelines recommend using recent respiratory cultures and locally validated epidemiology plus risk factor assessment to determine empirical coverage of methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. To develop a methodology for evaluating local epidemiology and validating local risk factors for P aeruginosa and MRSA. This multicenter, retrospective cohort evaluated adult patients admitted for pneumonia. Risk factors for MRSA and P aeruginosa were evaluated using multivariable logistic regression and reported as adjusted odds ratios (aORs). There were 10 723 cases evaluated. Lung abscess/empyema had the highest odds associated with MRSA (aOR = 4.24; P < 0.0001), followed by influenza (aOR = 2.34; P = 0.01), end-stage renal disease (ESRD; aOR = 2.09; P = 0.006), illicit substance use (aOR = 1.7; P = 0.007), and chronic obstructive pulmonary disease (COPD; aOR = 1.26; P = 0.04). For P aeruginosa, the highest odds were in bronchiectasis (aOR = 6.13; P < 0.0001), lung abscess/empyema (aOR = 3.36; P = 0.005), and COPD (aOR = 1.84; P < 0.0001). Isolated COPD without other risk factors did not pose an increased risk of either organism. Influenza, ESRD, lung abscess/empyema, and illicit substance use were local risk factors for MRSA. Bronchiectasis and lung abscess/empyema were risk factors for Pseudomonas. COPD was associated with MRSA and Pseudomonas. However, isolated COPD had similar rates of MRSA and Pseudomonas pneumonia compared with the total population. This study established a feasible methodology for evaluating local risk factors.