Search

Background. Healthcare-associated infections pose a potentially fatal threat to patients worldwide and Staphylococcus aureus is one of the most common causes of healthcare-associated infections. S. aureus is a common commensal pathogen and a frequent cause of bacteremia, with studies demonstrating that nasal and blood isolates from single patients match more than 80% of the time. Here we report on a contemporary collection of colonizing isolates from those with methicillin-resistant S. aureus (MRSA) bloodstream infections to evaluate the diversity within hosts, and detail the clinical features associated with concomitant nasal colonization.Methods. Swabs of the bilateral anterior nares were obtained from patients diagnosed with MRSA bacteremia. A single colony culture from the blood and an average of 6 colonies from the nares were evaluated for MRSA growth. For the nares cultures, we typed multiple isolates for staphylococcal protein A (spa) and derived the clonal complexes. Demographic and clinical data were obtained retrospectively from the electronic medical record system and analysed using univariate and multivariable regression models.Results. Over an 11-month period, 68 patients were diagnosed with MRSA bloodstream infection, 53 were swabbed, and 37 (70%) were colonized with MRSA in the anterior nares. We performed molecular typing on 210 nasal colonies. Spa types and clonal complexes found in the blood were also detected in the nares in 95% of the cases. We also found that 11% of patients carried more than one clone of MRSA in the nares. Male sex and history of prior hospitalization within the past 90 days increased odds for MRSA colonization. Conclusion. The molecular epidemiological landscape of colonization in the setting of invasive disease is diverse and defining the interplay between colonization and invasive disease is critical to combating invasive MRSA disease.

Background Previous viral pandemics have shown that secondary bacterial infections result in higher morbidity and mortality, with Staphylococcus aureus being the primary causative pathogen. The impact of secondary S. aureus bacteremia on mortality in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains unknown. Methods This was a retrospective observational case series of patients with coronavirus disease 2019 (COVID-19) who developed secondary S. aureus bacteremia across 2 New York City hospitals. The primary end point was to describe 14-day and 30-day hospital mortality rates of patients with COVID-19 and S. aureus bacteremia. Secondary end points included predictors of 14-day and 30-day hospital mortality in patients with COVID-19 and S. aureus bacteremia. Results A total of 42 patients hospitalized for COVID-19 with secondary S. aureus bacteremia were identified. Of these patients, 23 (54.8%) and 28 (66.7%) died at 14 days and 30 days, respectively, from their first positive blood culture. Multivariate analysis identified hospital-onset bacteremia (≥4 days from date of admission) and age as significant predictors of 14-day hospital mortality and Pitt bacteremia score as a significant predictor of 30-day hospital mortality (odds ratio [OR], 11.9; 95% CI, 2.03–114.7; P = .01; OR, 1.10; 95% CI, 1.03–1.20; P = .02; and OR, 1.56; 95% CI, 1.19–2.18; P = .003, respectively). Conclusions Bacteremia with S. aureus is associated with high mortality rates in patients hospitalized with COVID-19. Further investigation is warranted to understand the impact of COVID-19 and secondary S. aureus bacteremia.

Background Methicillin-resistant Staphylococcus aureus (MRSA) causes life-threatening infections in both community and hospital settings and is a leading cause of health care–associated infections (HAIs). We sought to describe the molecular epidemiological landscape of patients with MRSA bloodstream infections (BSIs) at an urban medical center by evaluating the clinical characteristics associated with the two dominant endemic clones. Methods Comprehensive clinical data from the electronic health records of 227 hospitalized patients ≥18 years old with MRSA BSI over a 33-month period in New York City were collected. The descriptive epidemiology and mortality associated with the two dominant clones were compared using logistic regression. Results Molecular analysis revealed that 91% of all single-patient MRSA BSIs were due to two equally represented genotypes, clonal complex (CC) 5 (n = 117) and CC8 (n = 110). MRSA BSIs were associated with a 90-day mortality rate of 27%. CC8 caused disease more frequently in younger age groups (56 ± 17 vs 67 ± 17 years old; P < .001) and in those of nonwhite race (odds ratio [OR], 3.45; 95% confidence interval [CI], 1.51–7.87; P = .003), with few other major distinguishing features. Morbidity and mortality also did not differ significantly between the two clones. CC8 caused BSIs more frequently in the setting of peripheral intravenous catheters (OR, 5.96; 95% CI, 1.51–23.50; P = .01). Conclusions The clinical features distinguishing dominant MRSA clones continue to converge. The association of CC8 with peripheral intravenous catheter infections underscores the importance of classical community clones causing hospital-onset infections. Ongoing monitoring and analysis of the dynamic epidemiology of this endemic pathogen are crucial to inform management and prevent disease.

Background Methicillin-resistant Staphylococcus aureus (MRSA) is a serious nosocomial pathogen, and is listed as a “High Priority Pathogen” by the WHO due to concerns of antimicrobial resistance and lack of novel therapeutics. Even in vancomycin-susceptible MRSA, increased rates of treatment failure occur in the setting of an increased minimum inhibitory concentration (MIC) to vancomycin, which is considered the gold-standard of therapy. We performed a case series of 25 patients infected with MRSA with an elevated MIC to vancomycin. Additionally, we describe the use of combination therapy with beta-lactams for the management of these highly complex cases. Methods We conducted a retrospective case series of 25 patients hospitalized at MSH between 8/2014–5/2019 who were treated for MRSA bacteremia where the isolate had an MIC ≥ 2. Data was centralized into the REDCap program. Clonal typing of bacteria and analysis of clinical features were performed in SAS and R. Results In total, 25 patients developed MRSA bacteremia with a vancomycin MIC ≥ 2. The majority of cases involved infection from vascular access, arteriovenous fistula/graft, and septic joint/osteomyelitis. All 25 patients were initially treated with vancomycin, with modification of therapy varying widely depending on clinician. The most common vancomycin-alternative was daptomycin (14/25 patients, alone and in combination). Combination therapy with vancomycin or daptomycin and a beta-lactam was used in 9 cases (36% of cases). Average number of days to clearance was 18.3 (range 1–69 days). Univariate and multivariate analyses revealed significant correlation MRSA bacteremia with vancomycin MIC ≥ 2 and admission from a nursing home or skilled nursing facility (p=0.02), history of MRSA colonization (p=0.006), and persistent bacteremia (bacteremia >7 days)(p< .0.001). Conclusion With few novel therapeutics under development, management of MRSA bacteremia with a rising MIC to vancomycin is a clinical challenge for practitioners. In our case series we found that treatment is largely patient and practitioner-dependent, and far from standardized. Further definition of the clinical risk factors for development and novel therapeutic strategies will enable understanding of how to best manage these challenging infections. Disclosures All Authors: No reported disclosures

Background Staphylococcus aureus is a common commensal pathogen and a frequent cause of bacteremia, with nasal and blood isolates from single patients matching >80% of the time. Based on our prior work on paired single-patient isolates,1 our aim was to collect a contemporary set of colonizing isolates from those with methicillin-resistant S. aureus (MRSA) bloodstream infections (BSIs), evaluate the within-host diversity by whole-genome sequencing (WGS), and detail the clinical features linked to colonization. Methods Adult patients with MRSA BSIs were screened for MRSA in the anterior nares from July 2018 to March 2019. Blood isolates underwent WGS, and spa and agr function screens were performed on three unique nasal isolates per patient. Clinical data from the electronic medical records underwent uni- and multivariate analyses on clinical features and outcomes. Results Of 55 unique patients with MRSA BSIs, screening of 45 subjects revealed that 67% were colonized with MRSA. The majority (64%) were males, 32% had prior colonization, and the most common infection sources were vascular access (27%), skin (24%), and unknown (24%). For those with nasal colonization, blood isolates were composed of 57% clonal complex (CC)5/t002, 33% CC8/t008, and 10% other. 81% of nasal isolates matched the blood, with 20% of nasal isolates harboring diverse spa types and 23% carried agr mutants. During this time frame, WGS found one transmission event involving a colonized subject. Colonization was associated with male gender (OR=4.52 95% CI [1.05–19.49]; P = 0.04) and prior hospital admission within the last 3 months (OR=6.12 95% CI [1.44–26.09]; P = 0.01) in multivariate analysis, with no differences in outcomes. Conclusion Colonization is an important component of invasive MRSA disease, and we found high rates of colonization with a predominance of the CC5. We also noted significant diversity and high proportion of agr mutants. At-risk groups included males and those with prior hospitalization. Combined molecular and clinical analyses can define the intrahost and interhost transmission dynamics of MRSA, and enables the development of targeted approaches in order to curtail disease. 1. Altman, D. R. et al. Genome Plasticity of agr-defective Staphylococcus aureus during clinical infection. Infect. Immun.(2018). Disclosures All authors: No reported disclosures.