Community-onset Methicillin-resistant Staphylococcus Aureus Research Articles

Relapsing bronchopneumonia due to community-associated methicillin-resistant Staphylococcus aureus: a case report

BackgroundThe emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has increased the incidence of community-onset MRSA infection. Respiratory tract infections caused by MRSA has been noted for their severity; however, repeated relapses that require extended antibiotic therapy are rare.Case presentationWe report a case of relapsing bronchopneumonia caused by CA-MRSA in a 56-year-old man. The patient responded to antibiotics, but repeatedly relapsed after stopping treatment. MRSA was consistently isolated from airway specimens during each relapse. Extended oral antibiotic treatment with trimethoprim/sulfamethoxazole (TMP/SMX) for 6 months achieved infection control. Whole-genome sequencing of the isolated strain revealed that the causative agent was sequence type (ST)1/staphylococcal cassette chromosome mec (SCCmec) type IVa, a clone that is rapidly increasing in Japan.Discussion and conclusionsThis patient had an unusual course of MRSA bronchopneumonia with repeated relapses. Although the choice of antibiotics for long-term use in MRSA respiratory tract infections has not been well established, TMP/SMX was effective and well tolerated for long-term therapy in this case. The clinical course of infections related to the rapid emerging clone, ST1/SCCmec type IVa warrants further attention.

Methicillin resistant Staphylococcus aureus infections in children: A prospective study

Community acquired MRSA (CA MRSA) can cause invasive diseases posing a challenge to treating physicians. The knowledge about the disease load, clinical pattern, risk factors, outcome and susceptibility pattern in a given geo demographic context contribute crucially to the treatment outcome of MRSA infections in children. To study the profile, clinical pattern, factors affecting the immediate outcome and antimicrobial susceptibility of MRSA infections in children A prospective observational study was conducted in children between 2 months and 12 years admitted with MRSA infections, from January 2016 to December 2017 in the Institute of Maternal and Child Health, Government Medical College Kozhikode, Kerala state, India. Out of 431 children evaluated 83(19.3%) had MRSA infections with 44(53%) CA MRSA and 39(47%) hospital associated MRSA (HA MRSA). Twenty one (53.8%) of HA MRSA infections were hospital onset MRSA (HAHO MRSA) and 18(46.2%) community onset MRSA (HACO MRSA). There were 37 infants, 16 toddlers, 12 preschool children, 18 school children, 48 males and 35 females in the study population. Blood (50.6%), pus (33.7%), and body fluids (15.7%) were the sites of isolation. Skin and soft tissue infections (SSTI)(30.10%), pneumonia (28.90%), empyema (9.64%), meningitis (7.23%), septicaemia (12.05%), bone and joint infections (9.64%), peritonitis (2.41%) and septic shock (18.1%) were the clinical presentation. Mortality occurred in 9.9% and paediatric intensive care requirement in 45.8% patients. Anaemia and thrombocytopenia were identified as the risk factors for PICU admissions (corrected OR; 95% C I, 3.38; 1.02–11.18 and 8.35; 1.35–45.03 respectively). Thrombocytopenia was associated with mortality (corrected OR 43.74, 95% C I 3.86–495.9). Susceptibility to clindamycin, co-trimoxazole, amikacin and rifampicin were 79.5%, 73.5%, 68.7% and 90.4% respectively. MRSA constituted a significant proportion of bacterial infections in children, the majority being community onset. Pneumonia and empyema predominate over SSTI. Thrombocytopenia was associated with mortality and PICU admission. Clindamycin, co-trimoxazole and amikacin can be utilised in the treatment of less severe MRSA infections

2455. National Trends in the Rates of Drug-resistant Bacteria Commonly Associated with Healthcare in U.S. Acute Care Hospitals, 2019-2021

Abstract Background The 2022 Special Report: COVID-19 U.S. Impact on Antimicrobial Resistance identified significant increases in the rate of hospital-onset (HO) infections during the year 2020 for bacteria commonly associated with healthcare. Using the same data sources and methodology, we provide updated estimates for the year 2021. Methods We identified a cohort of patients from the PINC AI PHD and BD Research Insights databases with a clinical culture yielding an isolate of an organism of interest with accompanying susceptibility testing. Isolates from patients with no culture yielding the same resistance phenotype of interest in the previous 14 days were counted as an incident case. Community-onset (CO) cultures were obtained ≤ day 3 of hospitalization; HO cultures were obtained ≥ day 4. We used a raking-procedure to determine weights for extrapolating the number of discharges included in our sample to match the distribution of discharges, stratified by bed size, U.S. census division, urban/rural designation, and teaching status, for U.S. hospitals included in the American Hospital Association survey. We examined temporal trends using a multivariable logistic model incorporating a survey design with the corresponding weights and hospital designation as the specific cluster controlling for hospital characteristics, month of discharge, proportion of patients in specific age group, proportion of male patients, and database. Results were stratified by HO and CO. Results From 2019-2021, the overall number of hospitals contributing data was 640. HO rates were significantly higher in 2020 and 2021 compared with 2019. The HO rates of VRE, MDRPseu, and CRE were significantly higher in 2021 when compared to 2020 (Table 1). For CO infections, we found that MRSA rates decreased significantly during the study period, while VRE and CRAB were significantly higher in 2021 compared to 2019 (Table 1). Conclusion Hospital onset antibiotic resistant infection rates in 2021 remain higher than pre-pandemic rates with increasing rates for several pathogens in 2021 compared to 2020, while CO MRSA declined. As infections caused by resistant pathogens represent a serious threat to patient safety, further study of factors contributing to the continued increases and decreases may inform prevention strategies. Disclosures All Authors: No reported disclosures

1864. Trends in Staphylococcus aureus Bacteremia Rates among U.S. Acute Care Hospitals, January 2017- June 2021

Abstract Background Previous estimates of methicillin-resistant and -sensitive Staphylococcus aureus (MRSA, MSSA) bacteremia rates in hospitalized patients showed decreases in hospital-onset (HO) MRSA, no changes in community-onset (CO) MRSA and HO MSSA, and slight increases in CO MSSA rates from 2012–2017; more recent trends have not been well characterized. Methods We calculated monthly S. aureus bacteremia rates using microbiology data from hospitals reporting antibiotic susceptibility results in the Premier Healthcare Database from January 2017- June 2021. S. aureus blood isolates resistant to methicillin, oxacillin, or cefoxitin were categorized as MRSA. Positive blood cultures collected on or before hospital day 3 were categorized as CO; those collected on day 4 or later were categorized as HO. Annual rate differences were assessed using generalized estimating equation models with a negative binomial distribution adjusting for hospital bed size, teaching status, urban/rural designation, discharge month, census division, distributions of patient age, sex and race and hospital-level clustering. Results Among 11 million discharges from 356 hospitals, we identified 5,627 HO S. aureus bacteremia events: 2,558 (45%) MRSA and 3,069 (55%) MSSA. In 2017, we observed HO MRSA bacteremia rates of 0.41 and HO MSSA rates of 0.49 per 10,000 patient-days. Compared with 2017, adjusted rates of HO MRSA and MSSA bacteremia were significantly higher in 2019, 2020, and 2021 (Figure 1). Of 42,587 CO S. aureus bacteremia events, 19,107 (45%) were MRSA and 23,480 (55%) MSSA. CO MRSA bacteremia rates were lowest in 2017 (1.52 per 1,000 discharges), and adjusted rates were significantly higher in all later years (Figure 2); we observed significant regional variability in annual differences (p=0.018). The observed CO MSSA bacteremia rate was 2.03 per 1,000 discharges in 2017, and adjusted rates were significantly higher in 2020 and 2021. Figure 1.Hospital-Onset MRSA and MSSA Bacteremia Incidence Rate Ratios* with 95% confidence intervals, 2017 – 2021**.*Reference year =2017.**2021 includes data during January – June.***Statistically significant at p<0.05.Figure 2.Community-Onset MRSA and MSSA Bacteremia Incidence Rate Ratios* with 95% confidence intervals, 2017 - 2021***Reference year =2017.**2021 includes data during January – June.***Statistically significant at p<0.05. Conclusion In contrast with previous trends, recent S. aureus bacteremia rates in this cohort have increased in comparison to 2017. Potential explanations warranting exploration include differences in regional trends and pandemic-associated changes in inpatient risk, severity of illness, length of stay, and hospital utilization Disclosures All Authors: No reported disclosures.

2056. Trends in the Rates of Multidrug-resistant Bacteria Commonly Associated with Healthcare in U.S. Acute Care Hospitals, 2019-June 2021

Abstract Background Several studies demonstrated an increase in hospital-onset (HO) infections during the COVID-19 pandemic. We examined trends in the rates of multidrug-resistant (MDR) infections among acute care hospitals in the United States (U.S.) for bacteria commonly associated with healthcare: methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum cephalosporin resistance in Enterobacteriaceae suggestive of extended-spectrum beta-lactamase production (ESBL), vancomycin resistant Enterococcus (VRE), MDR Pseudomonas aeruginosa, carbapenem resistant Enterobacteriaceae (CRE), and carbapenem-resistant Acinetobacter species (CRAB). Methods We measured incidence of clinical cultures yielding the bacterial species of interest among hospitalized patients in a dynamic cohort of hospitals submitting data to the Premier Healthcare Database Special COVID-19 Release during 2019-June 2021. Community-onset (CO) cultures were obtained ≤ day 3 of hospitalization; HO were obtained ≥ day 4. We determined monthly hospital-specific rates for each species. We used generalized estimating equations (GEE) multivariable negative binomial regression models adjusting for hospital characteristics to examine trends. Results From 2019-June 2021, the overall number of hospitals contributing data was 318. Rates for each pathogen are shown in Figures 1 and 2. All pathogens’ HO rates were significantly higher in 2021 compared with 2019. The rates of ESBL, VRE, and CRE were also significantly higher in 2021 when compared to 2020 (Table 1a). For CO rates, we found that MRSA rates decreased significantly during the study period, while ESBL, VRE, and CRE increased with varying degree of significance (Table 1b). Rates of CO MDR Pseudomonas and CO CRAB did not significantly change. Conclusion Our study confirmed that the rates of several MDR infections increased during the COVID-19 pandemic through June 2021, especially HO infections. CO MRSA was the only pathogen with consistent and significant decline. As infections caused by MDR pathogens represent a serious threat to patient safety, further study of factors contributing to the emerging trends may inform prevention strategies during a pandemic. Disclosures All Authors: No reported disclosures.

Genomic Epidemiology Suggests Community Origins of Healthcare-Associated USA300 Methicillin-Resistant Staphylococcus aureus.

Hospital-onset (HO) methicillin-resistant Staphylococcus aureus (MRSA) infections have declined over the past decade due to infection control strategies; community-onset (CO) and healthcare-associated community-onset (HACO) MRSA, particularly USA300, has declined less. We examined the role of community strains to explain the difference. We performed whole-genome sequencing (WGS) on MRSA clinical isolates from Cook County Health patients during 2011-2014. We defined infections as CO, HO, or HACO epidemiologically. We integrated genomic, community exposure, and statewide hospital discharge data to infer MRSA origin. Among 1020 individuals with available WGS, most were USA300 wound infections (580 CO, 143 HO, 297 HACO). USA300 HO, CO, and HACO infections were intermixed on the USA300 phylogeny, consistent with common strains circulating across community and healthcare settings. Community exposures (eg, substance abuse, incarceration, homelessness) were associated with HACO and HO infections, and genetically linked individuals from both groups had little overlap in healthcare facilities, supporting community origins. Most repeat infections-over months to years-occurred in individuals persistently carrying their own strains. These individuals were more likely to have genetic linkages, suggesting a role of persistent colonization in transmission. Efforts to reduce presumed nosocomial USA300 spread may require understanding and controlling community sources and transmission networks, particularly for repeat infections.

Decrease in MRSA Bacteremia After Implementation of Intranasal Mupirocin Decolonization Protocol

Background: Methicillin-resistant Staphylococcus aureus (MRSA) remains a key pathogen in burn patients and is associated with increased morbidity and mortality. Disruption of skin barrier exposes these individuals to a myriad of infections. Various decolonization approaches, including chlorhexidine baths and intranasal mupirocin, have shown favorable outcomes in preventing MRSA infections in this cohort. Methods: In August 2020, a mupirocin decolonization protocol was implemented in Michigan’s largest trauma-level 1 burn intensive care unit. All patients admitted to the burn unit received daily intranasal mupirocin for the initial 5 days of hospitalization. We compared MRSA bacteremia rates per 1,000 patient days from January–July 2020 to those after August 2020. A hospital-acquired MRSA bacteremia infection was defined as a positive blood culture after hospital day 3. Patient characteristics and hospital course were collected through medical chart review. A 2-tailed t test was used for analysis. Results: We identified 5 cases of hospital-onset MRSA bacteremia and no cases of community-onset MRSA bacteremia. On average, there were 2.6 cases per 1,000 patient days before mupirocin implementation and 1.0 cases per 1,000 patient days after mupirocin implementation (P = .26) (Figure 1). In this patient cohort, the average total body surface area burned was 45.6% (range, 18%–90%), and 60% (n = 3) of patients had sputum culture positive for MRSA prior to developing bacteremia (Table 1). Also, 2 patients (40%) with MRSA bacteremia died. Notably, the patient in the postintervention cohort was admitted in July, prior to implementation. Conclusions: Implementation of a decolonization protocol with intranasal mupirocin in burn-surgery patients markedly decreased the incidence of MRSA bacteremia in this cohort. This is the first study to evaluate the use of mupirocin as a decolonizing agent in burn victims. Continued long-term surveillance is recommended, and this strategy has potential for application to other high-risk cohorts.Funding: NoDisclosures: None

Substance Use Diagnoses Among Persons with Community-Onset Methicillin-Resistant Staphylococcus aureus Bloodstream Infections

Background: In recent years, the historic declines in the incidence of methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSIs) in the United States have slowed. We examined trends in the incidence of community-onset (CO) MRSA BSIs among hospitalized persons with and without substance-use diagnoses. Methods: Using data from >200 US hospitals reporting to the Premier Healthcare Database (PHD) during 2012–2017, we conducted a retrospective study among hospitalized persons aged ≥18 years. MRSA BSIs with substance use were defined as hospitalizations having both a blood culture positive for MRSA and at least 1 International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) or ICD-10-CM diagnostic code for substance use including opioids, cocaine, amphetamines, or other substances (excluding cannabis, alcohol, and nicotine). MRSA BSIs were considered community onset when a positive blood culture was collected within 3 days of admission. We assessed annual trends and described characteristics of CO MRSA BSI hospitalizations, stratified by substance use. Results: Of 20,049 MRSA BSIs from 2012 to 2017, 17,634 (88%) were CO. Overall, MRSA BSI incidence decreased 7%, from 178.5 to 166.2 per 100,000 hospitalizations during the study period; However, CO MRSA BSI rates remained stable (152.7 to 149.9 per 100,000 hospitalizations). Among CO MRSA BSIs, 1,838 (10%) were BSIs with substance-use diagnoses; the incidence of CO MRSA BSIs with substance use increased 236% (from 8.2 to 27.6 per 100,000 hospitalizations) and represented a greater proportion of the CO MRSA rate over the study period (Fig. 1). The incidence of CO MRSA BSIs without substance use decreased 15% (from 144.5 to 122.4 per 100,000 hospitalizations). Patients with CO MRSA BSIs with substance use were younger (median, 40 vs 65 years), more likely to be female (50% vs 40%), white (79% vs 69%), and to leave against medical advice (15% vs 1%). Among patients not leaving against medical advice, CO BSI patients with substance-use diagnoses had longer lengths of stay (median, 11 vs 9 days), lower in-hospital mortality (9% vs 14%), and higher hospitalization costs (median, $22,912 vs $17,468) compared to patients without substance-use diagnoses. Conclusions: Although the overall CO MRSA BSI rate remained unchanged from 2012 to 2017, infections with substance use diagnoses increased >3-fold, and infections without substance use diagnoses decreased. These data suggest that the emergence of MRSA associated with substance-use diagnoses threatens potential progress in reducing the incidence of CO MRSA infections. Additional strategies may be needed to prevent MRSA BSI in patients with substance-use diagnoses, and to maintain national progress in the reduction of MRSA infections overall.Funding: NoneDisclosures: None

Molecular Epidemiology of Community-Onset (CO), Community-Onset Healthcare-Associated (CO-HA) and Hospital-Onset (HO) Methicillin-Resistant Staphylococcus aureus (MRSA)

Background: Previous work suggests an intermingling of community and hospital transmission networks driving the MRSA epidemic, but how those with CO-HA infections fit into the network remains unclear. We integrated epidemiologic data and whole-genome sequencing (WGS) from existing MRSA clinical isolates to determine whether there were distinguishable features of CO-HA MRSA infections that could guide interventions. Methods: We examined 955 existing clinical MRSA isolates from 2011 to 2013 from patients at Cook County Health, the major public healthcare network in Chicago, Illinois. We performed electronic and manual chart review to ascertain community (eg, illicit drug use, incarceration history) and healthcare exposures and comorbidities. WGS was performed on all sequences, and sequences were typed with multilocus sequence typing (MLST). We assessed the distribution of epidemiological factors and sequence type (ST) across onset type. Results: Infections were more frequent in males (70%); 61% of individuals with infection were African American and 21% were Hispanic. Overall, wound infections were the most common (81%) followed by blood (7%) and respiratory (6%). 82% of infections were ST8 (most USA300), 8% were ST5 (USA100) and 10% were other STs (Fig. 1a). Using standard epidemiologic definitions, we identified 523 CO, 295 CO-HA, and 137 HO infections. USA300 infections were common across CO, CO-HA, and HO categories, whereas USA100 was more frequently observed among CO-HA and HO. Current illicit drug use and history of incarceration—factors typically associated with CO-MRSA—were observed among both CO-HA and HO infections. 38% of CO-HA and 36% of HO had a history of MRSA infection or nasal colonization in the prior 6 months. As expected, 73% of CO-HA had a history of recent hospitalization, but this was also true for 44% of HO cases; points for intervention for both groups, especially CO-HA patients, include outpatient, inpatient, and ER care. Diabetes was common across categories, and HIV was more commonly observed among CO-HA cases (Fig. 1b). Conclusions: We characterized the genomic and epidemiologic features of CO-HA MRSA infections relative to CO and HO. By MLST and epidemiological analysis, CO-HA infections share similarities to both CO and HO. Although USA300 infections were the most common strain type, our findings highlight the need for WGS to discern relationships between individuals to understand the intermixing of healthcare and community networks for CO-HA infections. Higher resolution genomic analysis may help guide whether interventions need to be at hospital discharge or in the community to have the most impact on decreasing CO-HA MRSA infections.Funding: Funding: from CDC Broad Agency Announcement: Genomic Epidemiology of Community-Onset Invasive USA300 MRSA Infections; Contract ID: 75D30118C02923Disclosures: None

570. Impact of Discontinuation of Methicillin-Resistant Staphylococcus aureus Contact Precautions on Bloodstream Infection Rates at an Academic Medical Center

BackgroundContact precautions (CP) in methicillin-resistant Staphylococcus aureus (MRSA) patients along with hand hygiene has been considered a gold standard to prevent transmission. The actual impact of these measures in reducing MRSA infections is still controversial. At our institution, we evaluated the impact of discontinuation of MRSA CP on hospital-onset (HO) and community-onset (CO) MRSA bloodstream (BSI) rates. We also analyzed consequential cost savings.MethodsThe University of Mississippi Medical Center is a 700+ bed academic facility located in Jackson, MS. Patients admitted to any inpatient units with diagnoses or history of MRSA infection or colonization were subjected to CP during their stay. In July 2018, we discontinued MRSA CP across all inpatient units (except neonatal intensive care unit). HO MRSA BSI rate was calculated per National Healthcare Safety Network (NHSN) laboratory-identified event. CO MRSA BSI was reported per NHSN admission prevalence rate. One-way Analysis of Variance (ANOVA) was performed to compare pre-and post-intervention data.ResultsThere was a rise in HO MRSA BSI rate after discontinuation of CP (July 2018-March 2019) in comparison to the 9-month pre-intervention period (October 2017-June 2018); however, the difference was not statistically significant (1.79/10,000 patient-days vs. 1.2/10,000 patient-days; P = 0.056). Similarly, CO MRSA BSI prevalence rate did not show a statistically significant difference between pre- and post-intervention period (0.103 vs. 0.08; P = 0.584).The total annualized cost savings on personal protective equipment (PPE) was an estimated $193,398 post-intervention. Hand hygiene (HH) compliance was higher in post-intervention compared with pre-intervention period (83% vs. 78%, P = 0.0007).ConclusionAt our institute, discontinuation of MRSA CP was associated with an insignificant rise in HO MRSA BSI rates. No impact was observed on CO MRSA BSI prevalence. We had a 34% reduction in PPE expenditure. We observed an increase in HH compliance post-discontinuation of CP, but it did not reduce MRSA BSI rates. Further studies are needed to evaluate the impact of bundling hand hygiene practices with other horizontal strategies (prevention bundles, chlorhexidine bathing, environmental disinfection practices) in prevention of MRSA infections. Disclosures All authors: No reported disclosures.

558. Evaluating Length of Stay Data for Use in Targeting Prevention of Methicillin-Resistant Staphylococcus aureus (MRSA) Bloodstream Infections

BackgroundEvidence suggests that interventions such as MRSA decolonization are useful in the prevention of MRSA bloodstream infections (BSI) both during hospitalization and post-discharge. However, decolonization may be costly and have diminishing effectiveness when used on all inpatients. Hospital length of stay (LOS) is a known risk factor for MRSA BSI. To determine whether LOS could be useful in prioritizing patients for intervention, we aimed to evaluate (i) distribution of time from admission to hospital-onset (HO) MRSA BSI, and (ii) frequency and LOS of hospitalizations that preceded community-onset (CO) MRSA BSI.MethodsMRSA-positive blood cultures among adults admitted to New York hospitals from 2013 to 20s16 were identified in the Centers for Disease Control and Prevention’s (CDC’s) National Healthcare Safety Network (NHSN). We linked these data to admissions in New York’s hospital discharge dataset, the Statewide Planning and Research Cooperative System (SPARCS), where the NHSN blood culture collection date was between a patient’s SPARCS admission and discharge dates and there was an exact match for birth date, gender and facility. Time to MRSA BSI was defined as the number of days from admission (day 1) to collection of a blood culture positive for MRSA. We defined positive blood cultures collected on days 1–3 as CO, and those collected ≥day 4 as HO.ResultsWe linked 10,425 (79%) MRSA BSIs from NHSN to SPARCS. 78% (8,147) of MRSA BSIs were CO and 22% (2,278) were HO. The median time to HO MRSA BSI was 10 days (IQR 6–21) (Figure 1), in contrast to the median LOS for all hospitalizations of 4 days (IQR 3–7). By definition, 35% of all hospitalizations were never at risk of HO MRSA BSI because their LOS was < 4 days. Among CO MRSA BSI, 48% were discharged from a hospital in the 90 days preceding their BSI (Figure 2). The median LOS of these prior hospitalizations was 8 days (IQR 5–14), and 87% were at least 4 days in length.ConclusionOver half of HO MRSA BSI occur on or after day 10 of hospitalization and a large fraction of CO MRSA BSI had a lengthy hospitalization shortly before their BSI diagnosis. Our results suggest that patients likely to have a long LOS could be evaluated as potential targets for prevention strategies (e.g., decolonization) to reduce both HO and CO MRSA BSI. Disclosures All authors: No reported disclosures.

562. Reducing MRSA Bacteremia in Adult Patients through MRSA Decolonization Bundle

BackgroundPatients colonized with methicillin-resistant Staphylococcus aureus (MRSA) are at an increased risk of developing a subsequent MRSA infection. Moreover, these individuals may serve as an endogenous reservoir to spread the bacteria to other patients. In an attempt to reduce MRSA bacteremia rates, a decolonization protocol was developed and implemented at a tertiary teaching hospital in Detroit, Michigan. In this study, we evaluate the intervention’s impact on community-onset (CO) and hospital onset (HO) MRSA bacteremia rates.MethodsInfection Control developed an MRSA decolonization bundle for adults that consisted of daily Chlorhexidine gluconate (CHG) bathing and twice-daily nasal swabs with 10% Povidone–iodine (PI) or Nozin for individuals with iodine allergies. Patients with known risk factors for developing an MRSA infection, such as patients residing in an intensive care unit and/or undergoing specified procedure, were prescribed the bundle for their length of stay (Figure 1). Countraindications for nasal decolonization included inhalation injuries, CSF leaks, ENT surgeries, and transphenoidal surgeries. A retrospective chart review of high-risk patients was conducted to determine compliance with the elements of the MRSA decolonization bundle. Rates of CO and HO MRSA bacteremia per 1,000 patient-days were graphed against compliance with bundle elements (2 nasal swabs and 1 CHG bath per day). To quantify the correlation, a linear regression model and the Pearson coefficient was used.ResultsApproximately 2,000 and 1,000 opportunities for nasal decolonization and CHG bathing, respectively, were identified between September 2018 and March 2019. The data suggest a strong correlation between compliance with MRSA decolonization elements and rate of HO MRSA bacteremia (R2 = 0.785) and a moderate association between nasal decolonization and rate of CO bacteremia (R2 = 0.322) (Figures 2 and 3).ConclusionThe MRSA decolonization bundle of CHG bathing and nasal swabs appears to be an effective strategy to decrease HO MRSA bacteremia rates with higher bundle compliance being associated with lower rates of infection. Disclosures All authors: No reported disclosures.

A Spatial Analysis of Health Disparities Associated with Antibiotic Resistant Infections in Children Living in Atlanta (2002-2010).

Background:Antibiotic resistant bacteria like community-onset methicillin resistant Staphylococcus aureus (CO-MRSA) have continued to cause infections in children at alarming rates and are associated with health disparities. Geospatial analyses of individual and area level data can enhance disease surveillance and identify socio-demographic and geographic indicators to explain CO-MRSA disease transmission patterns and risks.Methods:A case control epidemiology approach was undertaken to compare children with CO-MRSA to a noninfectious condition (unintentional traumatic brain injury (uTBI)). In order to better understand the impact of place based risks in developing these types of infections, data from electronic health records (EHR) were obtained from CO-MRSA cases and compared to EHR data from controls (uTBI). US Census data was used to determine area level data. Multi-level statistical models were performed using risk factors determined a priori and geospatial analyses were conducted and mapped.Results:From 2002–2010, 4,613 with CO-MRSA and 34,758 with uTBI were seen from two pediatric hospitals in Atlanta, Georgia. Hispanic children had reduced odds of infection; females and public health insurance were more likely to have CO-MRSA. Spatial analyses indicate significant ‘hot spots’ for CO-MRSA and the overall spatial cluster locations, differed between CO-MRSA cases and uTBI controls.Conclusions:Differences exist in race, age, and type of health insurance between CO-MRSA cases compared to noninfectious control group. Geographic clustering of cases is distinct from controls, suggesting placed based factors impact risk for CO-MRSA infection.

Twenty-Year Trends in Antimicrobial Susceptibilities Among Staphylococcus aureus From the SENTRY Antimicrobial Surveillance Program.

Background Staphylococcus aureus is among the most common human pathogens, with therapy complicated by the epidemic spread of methicillin-resistant Staphylococcus aureus (MRSA).MethodsThe SENTRY Antimicrobial Surveillance Program evaluated the in vitro activity of >20 antimicrobials against 191 460 clinical S. aureus isolates collected from 427 centers in 45 countries from 1997 to 2016. Each center contributed isolates and clinical data for consecutive episodes of bacteremia, pneumonia in hospitalized patients, urinary tract infection, and skin and skin structure infection.ResultsOverall, 191 460 S. aureus isolates were collected, of which 77 146 (40.3%) were MRSA, varying geographically from 26.8% MRSA in Europe to 47.0% in North America. The highest percentage of MRSA was in nosocomial isolates from patients aged >80 years. Overall, MRSA occurrences increased from 33.1% in 1997–2000 to a high of 44.2% in 2005–2008, then declined to 42.3% and 39.0% in 2009–2012 and 2013–2016, respectively. S. aureus bacteremia had a similar trend, with nosocomial and community-onset MRSA rates peaking in 2005–2008 and then declining. Vancomycin activity against S. aureus remained stable (minimum inhibitory concentration [MIC]90 of 1 mg/L and 100% susceptibility in 2016; no increase over time in isolates with a vancomycin MIC >1 mg/L). Several agents introduced during the surveillance period exhibited in vitro potency against MRSA.ConclusionsIn a large global surveillance program, the rise of MRSA as a proportion of all S. aureus peaked a decade ago and has declined since, consistent with some regional surveillance program reports. Vancomycin maintained high activity against S. aureus, and several newer agents exhibited excellent in vitro potencies.

Incidence of community onset MRSA in Australia: least reported where it is Most prevalent

BackgroundThis is the first review of literature and synthesis of data on community onset methicillin resistant Staphylococcus aureus (CO-MRSA) infections in Australia. Incidence of CO-MRSA varies considerably in Australia, depending on geographic and demographic factors.MethodsData for the rates of MRSA infections were collected from articles identified using PubMed, Scopus, the grey literature and data from State and Federal Government Surveillance Systems. We synthesized data and developed a framework for how data was selected, collated, linked, organized and interpreted.ResultsThe results of our literature search demonstrates considerable gaps in the reporting of CO-MRSA in Australia. Consequently, total incidences were under reported; however the available data suggests the incidence varied between 44 (Tasmania) and 388 (southern Northern Territory) cases per 100,000 person years. Hospitalised cases of CO-MRSA varied between 3.8 (regional Victoria) and 329 (southern Northern Territory). Taking the median percentage of infections by site for all regions available, skin and soft tissue infections (SSTIs) consisted of 56% of hospitalized CO-MRSA, compared with bacteremias, which represented 14%. No region had a complete data set of CO-MRSA infections treated in out-patient settings and so incidences were underestimates. Nevertheless, estimates of the incidence of CO-MRSA treated outside hospitals varied between 11.3 (Melbourne) and 285 (Northern Territory) per 100,000 person-years. These infections were chiefly SSTIs, although urinary tract infections were also noted.Incidences of CO-MRSA blood-stream infections and outpatient skin and soft tissue infections have been increasing with time, except in Tasmania. CO-MRSA is observed to affect people living in remote areas and areas of socioeconomic disadvantage disproportionately.ConclusionsWe generated the first estimates of the incidence of CO-MRSA infections in Australia and identified stark regional differences in the nature and frequency of infections. Critically, we demonstrate that there has been a lack of consistency in reporting CO-MRSA and a general dearth of data. The only government in Australia that requires reporting of CO-MRSA is the Tasmanian, where the infection was least prevalent. Some regions of Australia have very high incidences of CO-MRSA. To improve surveillance and inform effective interventions, we recommend a standardized national reporting system in Australia that reports infections at a range of infection sites, has broad geographic coverage and consistent use of terminology. We have identified limitations in the available data that hinder understanding the prevalence of CO-MRSA.

Analysis of antimicrobial resistance and risk factors of community-onset methicillin-resistant staphylococcus aureus infection

Objective: To analyze risk factors and drug resistance of community-onset methicillin-resistant staphylococcus aureus (CO-MRSA) infection through the investigation of patients infected with CO-MRSA. Methods: The clinical data of 97 cases infected with community-onset staphylococcus aureus (COSA) was collected in this hospital from July 2016 to June 2017. Epidemiological survey method and the variables were determined according to expert consultation, literature and practical work experience. Results: Among 97 patients infected with COSA, the diagnosis rate of CO-MRSA was 21.65%(21/97). The drug sensitivity results showed that: CO-MRSA was high resistant to erythromycin, tetracycline and clindamycin, and the drug resistance rate exceeded 50%. Multiple variables were analyzed by Logistic regression. The usage of antimicrobial agents in the past three months and the history of hospitalization within one year were the independent risk factors. The MRSA infection rate was 57.89%(11/19) of the persons who had taken antibacterial agents in the recent three months.The MRSA infection rate was 48.28%(14/29) of the persons who had been hospitalized in the past one year. OR value of two risk factors was respectively 10.006(95%CI: 2.200-45.519, P=0.030) and 11.519(95%CI: 2.405-55.177, P=0.002). Conclusions: Most COSA is sensitive to methicillin, but CO-MRSA is multidrug resistant and has more risk factors. The clinicians should reasonably use the antibacterial agents according to the drug sensitivity in order to prevent the occurrence of multidrug resistant MRSA.

Prevalence of Fosfomycin Resistance in Methicillin-Resistant Staphylococcus aureus Isolated from Patients in a University Hospital in China from 2013 to 2015.

In this study, we investigated the fosfomycin susceptibility rates among different methicillin-resistant Staphylococcus aureus (MRSA) clones. A total of 293 MRSA isolates obtained from Sir Run Run Shaw hospital during 2013-2015 were tested for fosfomycin susceptibility. The overall fosfomycin resistance rate among these MRSA isolates was 53.2%. Although 91.9% of the ST5 MRSA isolates (MIC50>1,024 mg/L) were resistant to fosfomycin, no fosfomycin-resistant isolate was found among the 69 ST59 MRSA isolates (MIC50/90, 0.5/4 mg/L). The fosfomycin resistance rate among the MRSA isolates recovered from skin and soft tissue infections was 19.1%, which was lower than the rates detected among MRSA isolates from other types of invasive infections. The fosfomycin resistance rate in community-onset MRSA was 30.2%, which was lower than that detected in healthcare-associated MRSA of 70.7%. One MRSA isolate had the fosB7 gene, whereas most (127/156) of the fosfomycin-resistant MRSA isolates had deletions in glpT genes. These findings highlight the importance of monitoring the fosfomycin susceptibility in MRSA isolates for epidemiological purposes.

Multidrug and Mupirocin Resistance in Environmental Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates from Homes of People Diagnosed with Community-Onset MRSA Infection.

Patients with community-onset (CO) methicillin-resistant Staphylococcus aureus (MRSA) infections contribute to MRSA contamination of the home environment and may be reexposed to MRSA strains from this reservoir. This study evaluates One Health risk factors, which focus on the relationship between humans, animals, and the environment, for the increased prevalence of multiple antimicrobial-resistant MRSA isolates in the home environment. During a trial of patients with CO-MRSA infection, MRSA was isolated from the household environment at the baseline and 3 months later, following randomization of patients and household members to mupirocin-based decolonization therapy or an education control group. Up to two environmental MRSA isolates collected at each visit were tested. MRSA isolates were identified in 68% (65/95) of homes at the baseline (n = 104 isolates) and 51% (33/65) of homes 3 months later (n = 56 isolates). The rates of multidrug resistance (MDR) were 61% among isolates collected at the baseline and 55% among isolates collected at the visit 3 months later. At the baseline, 100% (14/14) of MRSA isolates from rural homes were MDR. While antimicrobial use by humans or pets was associated with an increased risk for the isolation of MDR MRSA from the environment, clindamycin use was not associated with an increased risk for the isolation of MDR MRSA. Incident low-level mupirocin-resistant MRSA strains were isolated at 3 months from 2 (5%) of 39 homes that were randomized to mupirocin treatment but none of the control homes. Among patients recently treated for a CO-MRSA infection, MRSA and MDR MRSA were common contaminants in the home environment. This study contributes to evidence that occupant use of antimicrobial drugs, except for clindamycin, is associated with MDR MRSA in the home environmental reservoir. (This study has been registered at ClinicalTrials.gov under registration no. NCT00966446.)IMPORTANCE MRSA is a common bacterial agent implicated in skin and soft tissue infections (SSTIs) in both community and health care settings. Patients with CO-MRSA infections contribute to environmental MRSA contamination in these settings and may be reexposed to MRSA strains from these reservoirs. People interact with natural and built environments; therefore, understanding the relationships between humans and animals as well as the characteristics of environmental reservoirs is important to advance strategies to combat antimicrobial resistance. Household interactions may influence the frequency and duration of exposure, which in turn may impact the duration of MRSA colonization or the probability for recurrent colonization and infection. Therefore, MRSA contamination of the home environment may contribute to human and animal recolonization and decolonization treatment failure. The aim of this study was to evaluate One Health risk factors that may be amenable to intervention and may influence the recovery of MDR and mupirocin resistance in CO-MRSA isolates.

Swine exposure and methicillin-resistant Staphylococcus aureus infection among hospitalized patients with skin and soft tissue infections in Illinois: A ZIP code-level analysis

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA), a bacterial pathogen, is a predominant cause of skin and soft tissue infections (SSTI) in the United States. Swine-production facilities have been recognized as potential environmental reservoirs of MRSA. To better understand how swine production may contribute to MRSA infection, we evaluated the association between MRSA infection among SSTI inpatients and exposure measures derived from national swine inventory data. MethodsBased on adjusted odds ratios from logistic regression models, we evaluated the association between swine exposure metrics and MRSA infections among all Illinois inpatient hospitalizations for SSTI from January 2008 through July 2011. We also assessed if swine exposures had greater association with suspected community-onset MRSA (CO-MRSA) compared to suspected hospital-onset MRSA (HO-MRSA). Exposures were estimated using the Farm Location and Agricultural Production Simulator, generating the number of farms with greater than 1000 swine per residential ZIP code and the residential ZIP code-level swine density (swine/km2). ResultsFor every increase in 100 swine/km2 within a residential ZIP code, the adjusted OR (aOR) for MRSA infection was 1.36 (95% CI: 1.28−1.45). For every additional large farm (i.e., >1000 swine) per ZIP code, the aOR for MRSA infection was 1.06 (95% CI: 1.04−1.07). The aOR for ZIP codes with any large farms compared to those with no large farms was 1.24 (95% CI: 1.19−1.29). We saw no evidence of an increased association for CO-MRSA compared to HO-MRSA with either continuous exposure metric (aORs=0.99), and observed inconsistent results across exposure categories. ConclusionsThese publicly-available, ecological exposure data demonstrated positive associations between swine exposure measures and individual-level MRSA infections among SSTI inpatients. Though it is difficult to draw definitive conclusions due to limitations of the data, these findings suggest that the risk of MRSA may increase based on indirect environmental exposure to swine production. Future research can address measurement error related to these data by improving exposure assessment precision, increased specification of MRSA strain, and better characterization of specific environmental exposure pathways.

Genetic diversity of pvl- positive community-onset methicillin-resistant Staphylococcus aureus isolated at a university hospital in Japan

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is pathogenic to healthy individuals and a significant issue throughout the world. Panton-Valentine leukocidin gene (pvl)-positive sequence type (ST) 8-staphylococcal cassette chromosome (SCC) mec type IV (ST8-IV) as represented by the USA300 clone, is the most prevalent CA-MRSA in many countries. However, the prevalence of pvl-positive CA-MRSA was limited in Japan. Here, we report the incidence of pvl-positive community-onset MRSA (CO-MRSA) isolated from 10 patients seen between 2009 and 2014at a Japanese university hospital. All patients were Japanese and eight cases involved severe skin infections. Antimicrobial susceptibility patterns of the pvl-positive isolates were consistent with those of a typical CA-MRSA clone. Detailed molecular epidemiological analyses showed that three isolates were ST8-IV USA300 clones, whereas the other seven were ST30-IV (three isolates), ST30-I (one isolate), ST59-V (two isolates), and ST1-V (one isolate) clones. No clear difference of infection severity was found between the patients associated with the USA300 clone and those with the other clones. Our findings show that, not only the USA300 clone, but also diverse pvl-positive CO-MRSA clones exist in the community and cause severe skin infections in Japan.