Faculty Bibliography

Background. Staphylococcus aureus infection confers high mortality. S. aureus-colonized hospitalized patients are more likely to develop invasive infection and can transmit S. aureus to other patients in the absence of symptoms. Our health system has a baseline S. aureus colonization rate of 21% (MSSA and MRSA combined). To reduce risk of invasive S. aureus infection in our patients, we implemented an inpatient S. aureus screening and decolonization program. Methods. Interventions include universal S. aureus screening and targeted decolonization for all patients on the Medicine and Pediatrics inpatient services. Adult patients are screened at admission and change in the level of care; pediatric patients are screened weekly. S. aureus screening began incrementally by unit between 2016 and 2017, and extended to transplant units in 2018. All cultures are processed in the hospital microbiology lab for identification of MRSA and MSSA. S. aureus decolonization (mupirocin ointment in nares twice daily, chlorhexidine 2% wipes below the chin daily for 5 days) began in 2017 for patients with a central venous catheter, in intensive care unit or multibedded room. Decolonization was extended to all S. aureus-colonized patients beginning in June 2018, with involvement of a dedicated clinical nurse specialist. We compared compliance with screening and decolonization and the secondary outcome of MRSA bacteremia in the 6 month period before and after the addition of the clinical nurse specialist. Results. 21.5% of screened patients were colonized with S. aureus (82.4% MSSA, 17.6% MRSA). Screening compliance improved from 39.4% of eligible patients (N = 1805) to 52.1% (N = 2024) and decolonization increased from 18.6% of colonized patients to 41.2% comparing January-June 2018 with July-December 2018. The MRSA bacteremia rate fell from 0.2/1,000 patient-days in the first half of 2018 to 0.1/1,000 patient-days in the second half of 2018. Conclusion. A system-wide program that includes S. aureus screening and decolonization of hospitalized patients found that 21% of patients had S. aureus colonization. Screening and decolonization compliance increased with the introduction of a dedicated clinical nurse specialist, and the MRSA bloodstream infection rate fell

Background. Methicillin-resistant staphylococcus aureus (MRSA) colonization of hospitalized patients is associated with higher readmission rates and increased morbidity. Depending on the mechanisms of transmission, numerous potential control interventions exist to reduce the burden of disease. However, given the preponderance of asymptomatic colonization, it is challenging to quantify the relative importance of different transmission mechanisms and assess control efficacy. By identifying clusters of transmission, whole-genome sequencing (WGS) provides an opportunity to overcome these challenges. Methods. We sought to apply cluster analysis techniques to WGS data for MRSA, in order to assess MRSA prevalence, transmissibility, the degree of transmission heterogeneity and the potential effectiveness of control. Our model builds upon previous work that showed a direct relationship between the size distribution of infection clusters, the effective reproduction number (R) and the dispersion parameter (k). To demonstrate its functionality, our model was applied to existing WGS data for MRSA isolates collected during a 12 month period in the East of England (DOI: 10.1126/scitranslmed.aak9745) Results. The effective reproduction number for the East of England data is 0.29 (95% CI: 0.24-0.36). The dispersion parameter is 0.09 (0.03-0.33) reflecting a high degree of transmission heterogeneity. This implies all transmission is caused by just 12% of the cases. Targeted control of these cases could have decreased overall burden of MRSA colonization by 29% during the time period of the study. Conclusion. The high degree of transmission heterogeneity seen in MRSA transmission suggests that the risk for infection is variable.This observation motivates the need for more detailed mechanistic modeling of hospital-based MRSA transmission that integrates patients-specific factors, movement data and genome sequencing. Such models could be used to forecast which patients are at greatest risk for either acquiring or transmitting MRSA, thereby improving targeted control

AIMS/OBJECTIVE:non-anterior (NA) surgical approaches on prosthetic joint infection (PJI), and examined the impact of new perioperative protocols on PJI rates following all surgical approaches at a single institution. PATIENTS AND METHODS/METHODS:(13.3 to 57.6, sd 6.1), respectively. Infection rates were calculated yearly for the DA and NA approach groups. Covariates were assessed and used in multivariate analysis to calculate adjusted odds ratios (ORs) for risk of development of PJI with DA compared with NA approaches. In order to determine the effect of adopting a set of infection prevention protocols on PJI, we calculated ORs for PJI comparing patients undergoing THA for two distinct time periods: 2013 to 2014 and 2015 to 2016. These periods corresponded to before and after we implemented a set of perioperative infection protocols. RESULTS:There were 1985 patients in the DA group and 4101 patients in the NA group. The overall rate of PJI at our institution during the study period was 0.82% (50/6086) and decreased from 0.96% (12/1245) in 2013 to 0.53% (10/1870) in 2016. There were 24 deep PJIs in the DA group (1.22%) and 26 deep PJIs in the NA group (0.63%; p = 0.023). After multivariate analysis, the DA approach was 2.2 times more likely to result in PJI than the NA approach (OR 2.2 (95% confidence interval 1.1 to 3.9); p = 0.006) for the overall study period. CONCLUSION/CONCLUSIONS:2019;101-B(6 Supple B):2-8.

The past two decades have witnessed an alarming expansion of staphylococcal disease caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). The factors underlying the epidemic expansion of CA-MRSA lineages such as USA300, the predominant CA-MRSA clone in the United States, are largely unknown. Previously described virulence and antimicrobial resistance genes that promote the dissemination of CA-MRSA are carried by mobile genetic elements, including phages and plasmids. Here, we used high-resolution genomics and experimental infections to characterize the evolution of a USA300 variant plaguing a patient population at increased risk of infection to understand the mechanisms underlying the emergence of genetic elements that facilitate clonal spread of the pathogen. Genetic analyses provided conclusive evidence that fitness (manifest as emergence of a dominant clone) changed coincidently with the stepwise emergence of (i) a unique prophage and mutation of the regulator of the pyrimidine nucleotide biosynthetic operon that promoted abscess formation and colonization, respectively, thereby priming the clone for success; and (ii) a unique plasmid that conferred resistance to two topical microbiocides, mupirocin and chlorhexidine, frequently used for decolonization and infection prevention. The resistance plasmid evolved through successive incorporation of DNA elements from non-S. aureus spp. into an indigenous cryptic plasmid, suggesting a mechanism for interspecies genetic exchange that promotes antimicrobial resistance. Collectively, the data suggest that clonal spread in a vulnerable population resulted from extensive clinical intervention and intense selection pressure toward a pathogen lifestyle that involved the evolution of consequential mutations and mobile genetic elements.

Background. Catheter-associated urinary tract infections (CAUTI) negatively impact patient morbidity, mortality and insurance reimbursement rates in acute care hospitals. Since CAUTIs are solely defined by the National Health and Safety Network (NHSN), not by clinical definition or urinalysis (UA) result, eliminating unnecessary urine cultures will improve the accuracy of reportable CAUTI rates. Negative UA can accurately detect false-positive (FP) CAUTIs in patients with 100% negative predictive value. Methods. We conducted a retrospective analysis of 2017 CAUTIs reported from two acute care hospitals (A and B) to determine the effectiveness of a UA screening protocol and the distribution of FPs. Hospital B implemented a UA screening protocol requiring a UA prior to urine culture. Hospital A relied solely on microbiology cultures. FPs were identified by a negative UA result, the absence of bacteria, performed on the same or prior day to the urine culture that resulted in a CAUTI. Results. Our analysis showed that 13 (34%) of the 38 reported CAUTIs with an associated UA result at hospital A were FPs. Patients with a UC line duration >7 days had a CAUTI FP rate of 62% compared with 27% of those with a line duration between 3 and 7 days (Figure 1) (OR 4.6, CI: 0.9, 23.7, P = 0.09). Hospital A (no screening protocol) was 37.4 times more likely to have a FP CAUTI compared with hospital B (UA screening protocol) (CI: 2.1, 660.6; P < 0.0004). Conclusion. A positive culture with a negative UA is indicative of asymptomatic colonization, not true infection. Preventing FP CAUTIs would result in a 34% reduction in CAUTI rates at hospital A, placing the hospital in a better reimbursement benchmark (Figure 2). Interventions include: (1) A best practice alert in the patient's electronic medical record that can be used to notify the providers to re-evaluate patients with UCs in place >= 5 days, (2) A screening protocol that requires a UA order prior to/during specimen collection and prevents processing of urine cultures with a negative UA. In patients with UCs, a protocol should be implemented to reduce FP CAUTIs to better understand the true epidemiology of CAUTIs in hospitals and increase reporting accuracy. (Figure Presented)

Background. The multiplex polymerase chain reaction respiratory pathogen panel (RPP) is used frequently in emergency departments (EDs) for the rapid identification of viruses and atypical bacteria of the respiratory tract. Its clinical value is unclear, as numerous studies have demonstrated that its use has a limited impact on antibiotic prescribing. We aimed to describe the relationship between RPP results and antibiotic prescribing rates for ED patients in our large academic medical center. Methods. We retrospectively analyzed the charts of 1,061 patients aged 18-90 who were treated and released from two EDs from January 1, 2015 to January 31, 2018 and underwent RPP testing. Patients with evidence of bacterial infection were excluded based on RPP detection of atypical bacteria and microbiological analysis of blood, urine, wound, and sputum specimens. The results of the RPP and the rates of subsequent respiratory pathogen-directed antibiotic prescribing (including ED and outpatient pharmacy orders) were compared. Results. Antibiotic prescription rates were 21.5% in patients who tested negative for any respiratory virus, compared with 14.5% in patients who tested positive (OR 0.70, P < 0.01). When positive RPPs were subdivided based on virus type (influenza and non-influenza) and compared with negative RPPs, only influenza-detection was associated with a significant reduction in antibiotic prescriptions (Table 1). Conclusion. In our study population, the presence of a respiratory virus detected by the RPP was correlated with a significant decrease in antibiotic prescribing. This effect was largely driven by influenza detection. This demonstrates that at our institution, the RPP may have a role in reducing unnecessary antibiotic utilization, but providers need further guidance in the interpretation of non-influenza respiratory virus positivity. (Table Presented)

BACKGROUND: The timely identification of a cluster is a critical requirement for infection prevention and control (IPC) departments because these events may represent transmission of pathogens within the health care setting. Given the issues with manual review of hospital infections, a surveillance system to detect clusters in health care settings must use automated data capture, validated statistical methods, and include all significant pathogens, antimicrobial susceptibility patterns, patient care locations, and health care teams. METHODS: We describe the use of SaTScan statistical software to identify clusters, WHONET software to manage microbiology laboratory data, and electronic health record data to create a comprehensive outbreak detection system in our hospital. We also evaluated the system using the Centers for Disease Control and Prevention's guidelines. RESULTS: During an 8-month surveillance time period, 168 clusters were detected, 45 of which met criteria for investigation, and 6 were considered transmission events. The system was felt to be flexible, timely, accepted by the department and hospital, useful, and sensitive, but it required significant resources and has a low positive predictive value. CONCLUSIONS: WHONET-SaTScan is a useful addition to a robust IPC program. Although the resources required were significant, this prospective, real-time cluster detection surveillance system represents an improvement over historical methods. We detected several episodes of transmission which would have eluded us previously, and allowed us to focus infection prevention efforts and improve patient safety.

Background. Antibiotic (ABX) use and outcome measures (rate of HO-CDI, local antimicrobial resistance) are recommended ASP metrics. These metrics can be used for internal benchmarking to assess ASP performance within an institution over time. Methods. An adult ASP at our 750-bed academic medical center was implemented in 2008. ASP interventions include prospective audit and feedback, prior authorization with fuoroquinolone (FLQ) restriction as an ASP target and implementation of facility-specifc guidelines for common infections. Newer ASP initiatives were Cepheid/Xpert for blood cultures with Gram-positive cocci in pairs and clusters with daily real-time ASP interventions (11/2014), oral vancomycin secondary prophylaxis for patients with prior CDI (4/2014) and optimization of beta-lactam (BL) dosing (pip-eracillin-tazobactam [PTZ] extended infusion hospital-wide 4/2013; cefepime [CEF] 4/2015 and meropenem 7/2015 protocols). ABX use is measured in days of therapy per 1000 patient-days (DOT/1000 PD) and length of therapy/admission when ABX were administered (LOT/ADM). NHSN defnition is used for HO-CDI. For resistance trends the first unique isolate/patient/year regardless of source or susceptibility profle was included. Statistical analysis of trends during 8-years period 2009-2016 was performed by Poisson (SAS). Results. Major shifs in ABX use include decrease in FLQ use (-17%, P < 0.01) with compensatory increase in cefriaxone (CTX, +12%, P < 0.01), antipseudomonal BL (+3%, P < 0.01) and no change in carbapenem (+0.6%, P=0.5) as well as an increase in nafcillin and oxacillin (+7%, P < 0.01) use. There was a decrease in aggregate LOT/ADM (-4%, P < 0.01) with no change in DOT/1000 PD. We observed a decrease in HO-CDI rate (-17%, P < 0.01). Major resistance trends include reduction in Enterobacteriaceae spp. and Pseudomonas aeruginosa isolates nonsusceptible (NS) to FLQ (-4%, P < 0.01;-10%, P < 0.01, respectively) with increase in Enterobacteriaceae spp. NS to cefriaxone, (+3%, P < 0.01). A decrease in P. aeruginosa NS to PTZ (-11%, P < 0.01) and no change for CEF was reported. There was no Difference in Enterobacteriaceae spp. NS to PTZ or CEF. Conclusion. Overall, reported trends aligned with ASP initiatives. Increased CTX NS is of concern and warrants an ASP-led strategy to decrease CTX use

A global outbreak of invasive Mycobacterium chimaera infections after cardiac surgery has recently been linked to bioaerosols from contaminated heater-cooler units. The majority of cases have occurred after valvular surgery or aortic graft surgery and nearly half have resulted in death. To date, infections in patients with left ventricular assist devices (LVADs) have not been characterized in the literature. We report two cases of device-associated M. chimaera infection in patients with continuous-flow LVADs and describe challenges related to diagnosis and management in this population.