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In total, 13 facilities changed C. difficile testing to reflexive testing by enzyme immunoassay (EIA) only after a positive nucleic acid-amplification test (NAAT); the standardized infection ratio (SIR) decreased by 46% (range, −12% to −71% per hospital). Changing testing practice greatly influenced a performance metric without changing C. difficile infection prevention practice.

In total, 13 facilities changed

Updated Clostridioides difficile infection (CDI) guidelines published in 2018 recommend vancomycin as first-line treatment. Of 833 community-onset CDI cases in metropolitan Atlanta, Georgia in 2018, over half did not receive first-line treatment, although guideline adherence increased over the year. Second-line treatment was more common in patients treated in ambulatory settings.

Background: Nursing home (NH) residents are at high risk for Clostridioides difficile infection (CDI) due to older age, frequent antibiotic exposure, and previous healthcare exposure. Incidence of CDI attributed to NHs is not well established, but it is hypothesized to be related to the magnitude of transfers. We evaluated the relationship between NH CDI incidence and facility characteristics to explain variability in rates in Atlanta, Georgia. Methods: Incident C. difficile cases from 2016 to 2018 were identified through the Georgia Emerging Infections Program (funded by the Centers for Disease Control and Prevention), which conducts active population-based surveillance in the 8-county metro Atlanta area. An incident case was defined as an NH resident with a toxin-positive stool specimen (without a positive test within 8 weeks). Sampled (1 to 3 on age and gender) incident cases were attributed to a NH if a patient was an NH resident within 4 days of specimen collection. Facility characteristics (beds, resident days, admissions, and average length of stay [ALOS]) were obtained from NH cost reports, and facility-specific connectivity metrics were calculated (indegree and betweenness) from 2016 Medicare claims data. Case counts were aggregated to estimate yearly incidence and correlated with facility characteristics and location within the healthcare network using the Spearman correlation. A negative binomial model was used to assess residual variability in NH CDI incidence. Results: In total, 386 incident CDI cases were attributed to 64 NHs (range, 0–27). Approximately half (54.7%) resided in the NH at the time of specimen collection; however, 33.7% were in inpatient units (≤4 days of admission), and 10.9% were in an emergency room (ER). The frequency of NH CDI cases correlated strongly with admissions (r = .70; P < .01), inversely with ALOS (r = −0.53; P < .01), and moderately with resident days (r = .38; P < .01). After accounting for admissions, incidence (per 1,000 admissions) still varied (Fig. 1) (median 14; range, 0–34). The inverse association with ALOS decreased and incidence no longer correlated with the remaining facility characteristics or location within the healthcare transfer network (P > .05, all comparisons). However, there was residual correlation with connectivity metrics (indegree r = 0.26; P = .04). Conclusions: Our data suggest that attributing CDI to NHs requires the inclusion of hospital and ER-based specimen collection. NH CDI incidence appears highest among facilities with a low ALOS and a high number of admissions; incidence rates calculated per 1,000 admissions may best account for infection risk inherent early in a resident’s stay. Residual variability attributed to connectivity to the healthcare network was of borderline significance and should be further explored in the NH setting.Funding: NoneDisclosures: Scott Fridkin, consulting fee, vaccine industry (spouse)

Background: US hospitals are required to report C. difficile infections (CDIs) to the NHSN as a performance measure tied to payment penalties for poor scores. Currently, only the charted CDI test results performed last in reflex testing scenarios are reported to the NHSN (CDI events). We describe the reduction in NHSN CDI events from the addition of a reflex toxin enzyme immunoassay (EIA) after a positive nucleic acid amplification test (NAAT) in teaching and nonteaching hospitals, and we estimate the impact on standardized infection ratios (SIR). Methods: Reporting of all CDI test results, by test method, occurred during April 2018–July 2019 to the Georgia Emerging Infections program (funded by the Centers for Disease Control and Prevention), which conducts active population-based surveillance in an 8-county Atlanta area (population, 4 million). Among facilities starting reflex EIA testing, results were aggregated by test method during months of reflex testing to calculate facility-specific reduction in NHSN CDI events (% reduction; 1-[no. EIA+/no. NAAT+]). Differences in percent reduction between facilities by characteristic were compared using the Kruskal-Wallis test. We simulated expected changes in the SIR for a range of reductions, assuming equal effect on both community-onset (CO) and hospital-onset (HO) tests. Each facility’s historical NHSN CDI events prior to reflex testing were used to estimate changes to facility-specific SIRs by reducing values by the corresponding facility’s percent reduction. Results: Overall, 13 acute-care hospitals (bed size, 52–633; ICU bed size, 6–105) started reflex testing during the study period (mean, 7 months, 15,800 admissions, 66,400 patient days), resulting in 550 +NAAT tests reflexing to 180 +EIA tests (pooled mean 58% reduction). Percent reduction varied (mean, 67%; range, 42%–81%) but did not differ between larger (≥217 beds) and smaller hospitals (61 vs 50% reduction; P > .05) or by outsourced versus inhouse testing (65% vs 54% reduction; P > .05). Simulations identified a threshold reduction at which point effect on HO counteract the effects on CO events enough to reduce the SIR; thresholds for nonteaching and teaching were 26% and 32% reduction, respectively (Fig. 1). The estimated reductions in facility-specific SIRs using measured percent reductions on historic NHSN CDI events closely paralleled the simulation, and the mean estimated change in SIR was −46% (range, −12% to −71%) (Fig. 1). Conclusions: Although the magnitude of the effect varied, all 13 facilities experienced dramatic reductions in CDI events reportable to NHSN due to reflex testing; applying these reductions to historical NHSN data illustrates anticipated reductions in their facility-specific SIRs due to this testing change.Funding: NoneDisclosures: Scott Fridkin, consulting fee, vaccine industry (various) (spouse)

Background:Staphylococcus aureus is the leading cause of joint infections. These infections may arise in native or prosthetic joints. Previous analysis of population-based surveillance has documented racial differences in incidence of invasive S. aureus bloodstream infections. We hypothesized that racial differences in incidence would not persist among of S. aureus joint infections. Methods: We utilized data from the Georgia Emerging Infections Program (GA EIP), which conducts CDC-funded active, population-based surveillance for iSA within the 8-county area of Atlanta. Cases were defined as residents of the surveillance area with S. aureus isolated during 2016–2018 from joint fluid or tissue, and cultures within a 30-day period after the initial culture date were considered a single case. Age- and race-specific incidence were calculated using US census data; incidence rate ratios (RR) and adjusted rate ratios (aRR) were calculated using the Mantel-Hanzel method. Results: Between 2016 and 2018, 500 iSA joint infections were identified (iMRSA, 28.2% and iMSSA, 71.8%): 34.4% occurred in black patients and 65.6% occurred in white patients. Also, 90 cases (18%) had a bloodstream infection (BSI) within 30 days of the joint infection. Incidence of iSA joint infections dropped 22% from 9.4 per 100,000 in 2016 to 7.5 per 100,000 in 2018 (RR, 0.79; 95% CI, 0.7–0.9). Adjusting for year, incidence was 40% lower among blacks than whites (RR, 0.6,; 95% CI, 0.5–0.7); this finding was attributed to blacks having 60% lower incidence of iMSSA joint infections compared to whites (aRR, 0.4; 95% CI, 0.3–0.5) but similar MRSA incidence (aRR, 1.2; 95% CI, 0.8–1.6). The highest incidence was observed among whites aged >65 years with iMSSA infections (30.2 per 100,000) (Fig. 1). Among cases with a full chart review (n = 138), surgery in the prior 90 days was uncommon (n = 42, 30.4%), and a preceding major orthopedic procedure was even more rare (n = 13, 9.4%). Antecedent therapeutic injections and arthroscopic procedures are under investigation. Conclusions: Unlike S. aureus bacteremia, where previous analysis demonstrates higher incidences among blacks predominantly due to MRSA, our data demonstrate that the incidence of S. aureus joint infections is higher in whites, predominantly due to MSSA. Investigations in differential practices regarding orthopedic illness and injury should be pursued.Funding: NoneDisclosures: Scott Fridkin reports that his spouse receives consulting fees from the vaccine industry.