Seasonal and Temperature-Associated Increases in Gram-Negative Bacterial Bloodstream Infections among Hospitalized Patients

BACKGROUND: Knowledge of seasonal trends in hospital-associated infection incidence may improve surveillance and help guide the design and evaluation of infection prevention interventions. We estimated seasonal variation in the frequencies of inpatient bloodstream infections (BSIs) caused by common bacterial pathogens and examined associations of monthly BSI frequencies with ambient outdoor temperature, precipitation, and humidity levels. METHODS: A database containing blood cultures from 132 U.S. hospitals collected between January 1999 and September 2006 was assembled. The database included monthly counts of inpatient blood cultures positive for several clinically important Gram-negative bacteria (Acinetobacter spp, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) and Gram-positive bacteria (Enterococcus spp and Staphylococcus aureus). Monthly mean temperature, total precipitation, and mean relative humidity in the postal ZIP codes of participating hospitals were obtained from national meteorological databases. RESULTS: A total of 211,697 inpatient BSIs were reported during 9,423 hospital-months. Adjusting for long-term trends, BSIs caused by each gram-negative organism examined were more frequent in summer months compared with winter months, with increases ranging from 12.2% for E. coli (95% CI 9.2-15.4) to 51.8% for Acinetobacter (95% CI 41.1-63.2). Summer season was associated with 8.7% fewer Enterococcus BSIs (95% CI 11.0-5.8) and no significant change in S. aureus BSI frequency relative to winter. Independent of season, monthly humidity, monthly precipitation, and long-term trends, each 5.6°C (10°F) rise in mean monthly temperature corresponded to increases in gram-negative bacterial BSI frequencies ranging between 3.5% for E. coli (95% CI 2.1-4.9) to 10.8% for Acinetobacter (95% CI 6.9-14.7). The same rise in mean monthly temperature corresponded to an increase of 2.2% in S. aureus BSI frequency (95% CI 1.3-3.2) but no significant change in Enterococcus BSI frequency. CONCLUSIONS: Summer season and higher mean monthly outdoor temperature are associated with substantially increased frequency of BSIs, particularly among clinically important gram-negative bacteria

Advancing Epidemiological Science Through Computational Modeling: A Review with Novel Examples

Computational models have been successfully applied to a wide variety of research areas including infectious disease epidemiology. Especially for questions that are difficult to examine in other ways, computational models have been used to extend the range of epidemiological issues that can be addressed, advance theoretical understanding of disease processes and help identify specific intervention strategies. We explore each of these contributions to epidemiology research through discussion and examples. We also describe in detail models for raccoon rabies and methicillin-resis-tant Staphylococcus aureus, drawn from our own research, to further illustrate the role of computation in epidemiological modeling

Health and Economic Impact of Surgical Site Infections Diagnosed after Hospital Discharge

Although surgical site infections (SSIs) are known to cause substantial illness and costs during the index hospitalization, little information exists about the impact of infections diagnosed after discharge, which constitute the majority of SSIs. In this study, using patient questionnaire and administrative databases, we assessed the clinical outcomes and resource utilization in the 8-week postoperative period associated with SSIs recognized after discharge. SSI recognized after discharge was confirmed in 89 (1.9%) of 4,571 procedures from May 1997 to October 1998. Patients with SSI, but not controls, had a significant decline in SF-12 (Medical Outcomes Study 12-Item Short-Form Health Survey) mental health component scores after surgery (p=0.004). Patients required significantly more outpatient visits, emergency room visits, radiology services, readmissions, and home health aide services than did controls. Average total costs during the 8 weeks after discharge were US$5,155 for patients with SSI and$1,773 for controls (p<0.001)

Antibiotic stewardship implementation and patient-level antibiotic use at hospitals with and without on-site Infectious Disease specialists.

Many US hospitals lack Infectious Disease (ID) specialists, which may hinder antibiotic stewardship efforts. We sought to compare patient-level antibiotic exposure at Veterans Health Administration (VHA) hospitals with and without an on-site ID specialist, defined as an ID physician and/or ID pharmacist. This retrospective VHA cohort included all acute-care patient-admissions during 2016. A mandatory survey was used to identify hospitals' antibiotic stewardship processes and their access to an on-site ID specialist. Antibiotic use was quantified as days of therapy (DOT) per days-present and categorized based on National Healthcare Safety Network definitions. A negative binomial regression model with risk adjustment was used to determine the association between presence of an on-site ID specialist and antibiotic use at the level of patient-admissions. Eighteen of 122 (14.8%) hospitals lacked an on-site ID specialist; there were 525,451 (95.8%) admissions at ID hospitals and 23,007 (4.2%) at non-ID sites. In the adjusted analysis, presence of an ID specialist was associated with lower total inpatient antibacterial use [OR 0.92, (95% CI, 0.85-0.99)]. Presence of an ID specialist was also associated with lower use of broad-spectrum antibacterials [OR 0.61 (95% CI, 0.54-0.70)] and higher narrow-spectrum beta-lactam use [OR 1.43 (95% CI, 1.22-1.67)]. Total antibacterial exposure (inpatient plus post-discharge) was lower among patients at ID versus non-ID sites [OR 0.92 (95% CI, 0.86-0.99)]. Patients at hospitals with an ID specialist received antibiotics in a way more consistent with stewardship principles. The presence of an ID specialist may be important to effective antibiotic stewardship

Antibiotic Stewardship Implementation and Antibiotic Use at Hospitals With and Without On-site Infectious Disease Specialists.

BackgroundMany US hospitals lack infectious disease (ID) specialists, which may hinder antibiotic stewardship efforts. We sought to compare patient-level antibiotic exposure at Veterans Health Administration (VHA) hospitals with and without an on-site ID specialist, defined as an ID physician and/or ID pharmacist.MethodsThis retrospective VHA cohort included all acute-care patient admissions during 2016. A mandatory survey was used to identify hospitals' antibiotic stewardship processes and their access to an on-site ID specialist. Antibiotic use was quantified as days of therapy per days present and categorized based on National Healthcare Safety Network definitions. A negative binomial regression model with risk adjustment was used to determine the association between presence of an on-site ID specialist and antibiotic use at the level of patient admissions.ResultsEighteen of 122 (14.8%) hospitals lacked an on-site ID specialist; there were 525 451 (95.8%) admissions at ID hospitals and 23 007 (4.2%) at non-ID sites. In the adjusted analysis, presence of an ID specialist was associated with lower total inpatient antibacterial use (odds ratio, 0.92; 95% confidence interval, .85-.99). Presence of an ID specialist was also associated with lower use of broad-spectrum antibacterials (0.61; .54-.70) and higher narrow-spectrum β-lactam use (1.43; 1.22-1.67). Total antibacterial exposure (inpatient plus postdischarge) was lower among patients at ID versus non-ID sites (0.92; .86-.99).ConclusionsPatients at hospitals with an ID specialist received antibiotics in a way more consistent with stewardship principles. The presence of an ID specialist may be important to effective antibiotic stewardship

Implementation of antimicrobial stewardship policies in U.S. hospitals: findings from a national survey.

OBJECTIVE: To describe the use of antimicrobial stewardship policies and to investigate factors associated with implementation in a national sample of acute care hospitals. DESIGN: Cross-sectional survey. PARTICIPANTS: Infection Control Directors from acute care hospitals participating in the National Healthcare Safety Network (NHSN). METHODS: An online survey was conducted in the Fall of 2011. A subset of hospitals also provided access to their 2011 NHSN annual survey data. RESULTS: Responses were received from 1,015 hospitals (30% response rate). The majority of hospitals (64%) reported the presence of a policy; use of antibiograms and antimicrobial restriction policies were most frequently utilized (83% and 65%, respectively). Respondents from larger, urban, teaching hospitals and those that are part of a system that shares resources were more likely to report a policy in place (P CONCLUSION: This study provides a snapshot of the implementation of antimicrobial stewardship policies in place in U.S. hospitals and suggests that statewide efforts in California are achieving their intended effect. Further research is needed to identify factors that foster the adoption of these policies

Incidence and Outcomes Associated With Clostridium difficile Infections: A Systematic Review and Meta-analysis

Importance: An understanding of the incidence and outcomes of Clostridium difficile infection (CDI) in the United States can inform investments in prevention and treatment interventions. Objective: To quantify the incidence of CDI and its associated hospital length of stay (LOS) in the United States using a systematic literature review and meta-analysis. Data Sources: MEDLINE via Ovid, Cochrane Library Databases via Wiley, Cumulative Index of Nursing and Allied Health Complete via EBSCO Information Services, Scopus, and Web of Science were searched for studies published in the United States between 2000 and 2019 that evaluated CDI and its associated LOS. Study Selection: Incidence data were collected only from multicenter studies that had at least 5 sites. The LOS studies were included only if they assessed postinfection LOS or used methods accounting for time to infection using a multistate model or compared propensity score-matched patients with CDI with control patients without CDI. Long-term-care facility studies were excluded. Of the 119 full-text articles, 86 studies (72.3%) met the selection criteria. Data Extraction and Synthesis: Two independent reviewers performed the data abstraction and quality assessment. Incidence data were pooled only when the denominators used the same units (eg, patient-days). These data were pooled by summing the number of hospital-onset CDI incident cases and the denominators across studies. Random-effects models were used to obtain pooled mean differences. Heterogeneity was assessed using the I2 value. Data analysis was performed in February 2019. Main Outcomes and Measures: Incidence of CDI and CDI-associated hospital LOS in the United States. Results: When the 13 studies that evaluated incidence data in patient-days due to hospital-onset CDI were pooled, the CDI incidence rate was 8.3 cases per 10 000 patient-days. Among propensity score-matched studies (16 of 20 studies), the CDI-associated mean difference in LOS (in days) between patients with and without CDI varied from 3.0 days (95% CI, 1.44-4.63 days) to 21.6 days (95% CI, 19.29-23.90 days). Conclusions and Relevance: Pooled estimates from currently available literature suggest that CDI is associated with a large burden on the health care system. However, these estimates should be interpreted with caution because higher-quality studies should be completed to guide future evaluations of CDI prevention and treatment interventions

Using Audit and Feedback to Improve Antimicrobial Prescribing in Emergency Departments: A Multicenter Quasi-Experimental Study in the Veterans Health Administration

Background: In this pilot trial, we evaluated whether audit-and-feedback was a feasible strategy to improve antimicrobial prescribing in emergency departments (EDs). Methods: We evaluated an audit-and-feedback intervention using a quasi-experimental interrupted time-series design at 2 intervention and 2 matched-control EDs; there was a 12-month baseline, 1-month implementation, and 11-month intervention period. At intervention sites, clinicians received (1) a single, one-on-one education about antimicrobial prescribing for common infections and (2) individualized feedback on total and condition-specific (uncomplicated acute respiratory infection [ARI]) antimicrobial use with peer-to-peer comparisons at baseline and every quarter. The primary outcome was the total antimicrobial-prescribing rate for all visits and was assessed using generalized linear models. In an exploratory analysis, we measured antimicrobial use for uncomplicated ARI visits and manually reviewed charts to assess guideline-concordant management for 6 common infections. Results: In the baseline and intervention periods, intervention sites had 28 016 and 23 164 visits compared to 33 077 and 28 835 at control sites. We enrolled 27 of 31 (87.1%) eligible clinicians; they acknowledged receipt of 33.3% of feedback e-mails. Intervention sites compared with control sites had no absolute reduction in their total antimicrobial rate (incidence rate ratio = 0.99; 95% confidence interval, 0.98-1.01). At intervention sites, antimicrobial use for uncomplicated ARIs decreased (68.6% to 42.4%; P < .01) and guideline-concordant management improved (52.1% to 72.5%; P < .01); these improvements were not seen at control sites. Conclusions: At intervention sites, total antimicrobial use did not decrease, but an exploratory analysis showed reduced antimicrobial prescribing for viral ARIs. Future studies should identify additional targets for condition-specific feedback while exploring ways to make electronic feedback more acceptable

Incidence and Outcomes Associated With Infections Caused by Vancomycin-Resistant Enterococci in the United States: Systematic Literature Review and Meta-Analysis

Information about the health and economic impact of infections caused by vancomycin-resistant enterococci (VRE) can inform investments in infection prevention and development of novel therapeutics. To systematically review the incidence of VRE infection in the United States and the clinical and economic outcomes. We searched various databases for US studies published from January 1, 2000, through June 8, 2015, that evaluated incidence, mortality, length of stay, discharge to a long-term care facility, readmission, recurrence, or costs attributable to VRE infections. We included multicenter studies that evaluated incidence and single-center and multicenter studies that evaluated outcomes. We kept studies that did not have a denominator or uninfected controls only if they assessed postinfection length of stay, costs, or recurrence. We performed meta-analysis to pool the mortality data. Five studies provided incidence data and 13 studies evaluated outcomes or costs. The incidence of VRE infections increased in Atlanta and Detroit but did not increase in national samples. Compared with uninfected controls, VRE infection was associated with increased mortality (pooled odds ratio, 2.55), longer length of stay (3-4.6 days longer or 1.4 times longer), increased risk of discharge to a long-term care facility (2.8- to 6.5-fold) or readmission (2.9-fold), and higher costs ($9,949 higher or 1.6-fold more). VRE infection is associated with large attributable burdens, including excess mortality, prolonged in-hospital stay, and increased treatment costs. Multicenter studies that use suitable controls and adjust for time at risk or confounders are needed to estimate the burden of VRE infections