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The construction of two types of double-barreled microelectrodes of sufficiently small tip size to record cytosolic pH (pHc) in renal tubular epithelial cells is described. Mean pHc in control anesthetized rats was 7.10 and mean basolateral membrane potential (Em) was -51.8 mV. These results suggest that hydrogen ions are actively extruded from either or both poles of the proximal tubular cell but that bicarbonate exit across the basolateral membrane is passive. In animals treated with acetazolamide, pHc was significantly elevated (mean 7.35) but Em was unchanged, suggesting that proton extrusion continues but that the rate of reaction of OH- with CO2 is diminished due to carbonic anhydrase inhibition. A pH higher than that of arterial blood was obtained from sites presumed to be in the interstitium. The evidence for the various assignments of microelectrode tip position is discussed.

Background: Carbapenem-resistant Enterobacteriaceae (CRE) are endemic in the Chicago region. We assessed the regional impact of a CRE control intervention targeting high-prevalence facilities; that is, long-term acute-care hospitals (LTACHs) and ventilator-capable skilled nursing facilities (vSNFs). Methods: In July 2017, an academic–public health partnership launched a regional CRE prevention bundle: (1) identifying patient CRE status by querying Illinois’ XDRO registry and periodic point-prevalence surveys reported to public health, (2) cohorting or private rooms with contact precautions for CRE patients, (3) combining hand hygiene adherence, monitoring with general infection control education, and guidance by project coordinators and public health, and (4) daily chlorhexidine gluconate (CHG) bathing. Informed by epidemiology and modeling, we targeted LTACHs and vSNFs in a 13-mile radius from the coordinating center. Illinois mandates CRE reporting to the XDRO registry, which can also be manually queried or generate automated alerts to facilitate interfacility communication. The regional intervention promoted increased automation of alerts to hospitals. The prespecified primary outcome was incident clinical CRE culture reported to the XDRO registry in Cook County by month, analyzed by segmented regression modeling. A secondary outcome was colonization prevalence measured by serial point-prevalence surveys for carbapenemase-producing organism colonization in LTACHs and vSNFs. Results: All eligible LTACHs (n = 6) and vSNFs (n = 9) participated in the intervention. One vSNF declined CHG bathing. vSNFs that implemented CHG bathing typically bathed residents 2–3 times per week instead of daily. Overall, there were significant gaps in infection control practices, especially in vSNFs. Also, 75 Illinois hospitals adopted automated alerts (56 during the intervention period). Mean CRE incidence in Cook County decreased from 59.0 cases per month during baseline to 40.6 cases per month during intervention (P < .001). In a segmented regression model, there was an average reduction of 10.56 cases per month during the 24-month intervention period (P = .02) (Fig. 1), and an estimated 253 incident CRE cases were averted. Mean CRE incidence also decreased among the stratum of vSNF/LTACH intervention facilities (P = .03). However, evidence of ongoing CRE transmission, particularly in vSNFs, persisted, and CRE colonization prevalence remained high at intervention facilities (Table 1). Conclusions: A resource-intensive public health regional CRE intervention was implemented that included enhanced interfacility communication and targeted infection prevention. There was a significant decline in incident CRE clinical cases in Cook County, despite high persistent CRE colonization prevalence in intervention facilities. vSNFs, where understaffing or underresourcing were common and lengths of stay range from months to years, had a major prevalence challenge, underscoring the need for aggressive infection control improvements in these facilities.Funding: The Centers for Disease Control and Prevention (SHEPheRD Contract No. 200-2011-42037)Disclosures: M.Y.L. has received research support in the form of contributed product from OpGen and Sage Products (now part of Stryker Corporation), and has received an investigator-initiated grant from CareFusion Foundation (now part of BD).

BackgroundvSNF patients are at high risk of colonization and infection with C. auris. CHG bathing has been used as an intervention to reduce nosocomial transmission of multi-drug-resistant organisms, but its effect on C. auris is unclear.MethodsWe studied a 70-bed ventilator ward in a 300-bed vSNF in Chicago, IL with a high prevalence of C. auris and established CHG bathing. Swab samples were collected from patients for culture, microbiome analysis, and CHG skin concentration testing (Table 1).ResultsWe collected 2,467 samples (950 culture, 950 microbiome, 567 CHG) from 57 patients during 2 surveys conducted January–March 2019. Forty-six (81%) patients had C. auris cultured from ≥1 body site. Mean (±SD) age was 59 (±14) years, 40% were women, 70% were African American, mean (±SD) Charlson score was 3 (±2). Patients colonized with C. auris were more likely to be mechanically ventilated (50% vs. 0%, P < 0.001), have a gastrostomy tube (78% vs. 27%, P < 0.001) or have urinary catheter (72% vs. 23%, P = 0.01) than noncolonized patients. Frequency of C. auris isolation varied among 10 body sites tested (P < 0.001); colonization of anterior nares (41%) and hands (40%) was detected most often (Figure 1). By ITS1 analysis, all isolates were members of the C. auris South American clade. Skin microbiome sequencing confirmed culture Results. While Malassezia is the dominant genera observed in healthy volunteers and patients in this vSNF, C. auris was observed to dominate the fungal community of multiple skin sites, including nares, hands, inguinal, toe web (Figure 2). Other Candida spp. were also identified on the skin of patients in the current study, but at lower relative abundance. CHG was detected on skin of 52 (91%) patients (median CHG concentration 19.5 µg/mL; IQR 4.9–78.1 µg/mL). In a mixed-effects model controlling for body site and multiple measurements per patient, odds of C. auris detection by culture were less at CHG concentrations ≥625 µg/mL than at lower concentrations (Figure 3; OR 0.25, 95% CI: 0.10–0.66; P = 0.005).ConclusionFrequent C. auris colonization of vSNF patients’ anterior nares and hands suggests that nasal decolonization and patient hand hygiene are potential options to reduce C. auris transmission. High concentrations of CHG may be needed to suppress C. auris on skin. Disclosures All Authors: No reported Disclosures.

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