Association Between Implementation of the Severe Sepsis and Septic Shock Early Management Bundle Performance Measure and Outcomes in Patients With Suspected Sepsis in US Hospitals.

Importance: In October 2015, the Centers for Medicare & Medicaid Services began requiring US hospitals to report adherence to the Severe Sepsis and Septic Shock Early Management Bundle (SEP-1). Objective: To evaluate the association of SEP-1 implementation with sepsis treatment patterns and outcomes in diverse hospitals. Design, Setting, and Participants: This retrospective cohort study with interrupted time-series analysis and logistic regression models was conducted among adults admitted to 114 hospitals from October 2013 to December 2017 with suspected sepsis (blood culture orders, ≥2 systemic inflammatory response syndrome criteria, and acute organ dysfunction) within 24 hours of hospital arrival. Data analysis was conducted from September 2020 to September 2021. Exposures: SEP-1 implementation in the fourth quarter (Q4) of 2015. Main Outcomes and Measures: The primary outcome was quarterly rates of risk-adjusted short-term mortality (in-hospital death or discharge to hospice). Secondary outcomes included lactate testing and administration of anti-methicillin-resistant Staphylococcus aureus (MRSA) or antipseudomonal ß-lactam antibiotics within 24 hours of hospital arrival. Generalized estimating equations with robust sandwich variances were used to fit logistic regression models to assess for changes in level or trends in these outcomes, adjusting for baseline characteristics and severity of illness. Results: The cohort included 117 510 patients (median [IQR] age, 67 years [55-78] years; 60 530 [51.5%] men and 56 980 [48.5%] women) with suspected sepsis. Lactate testing rates increased from 55.1% (95% CI, 53.9%-56.2%) in Q4 of 2013 to 76.7% (95% CI, 75.4%-78.0%) in Q4 of 2017, with a significant level change following SEP-1 implementation (odds ratio [OR], 1.34; 95% CI, 1.04-1.74). There were increases in use of anti-MRSA antibiotics (19.8% [95% CI, 18.9%-20.7%] in Q4 of 2013 to 26.3% [95% CI, 24.9%-27.7%] in Q4 of 2017) and antipseudomonal antibiotics (27.7% [95% CI, 26.7%-28.8%] in Q4 of 2013 to 40.5% [95% CI, 38.9%-42.0%] in Q4 of 2017), but these trends preceded SEP-1 and did not change with SEP-1 implementation. Unadjusted short-term mortality rates were similar in the pre-SEP-1 period (Q4 of 2013 through Q3 of 2015) vs the post-SEP-1 period (Q1 of 2016 through Q4 of 2017) (20.3% [95% CI, 20.0%-20.6%] vs 20.4% [95% CI, 20.1%-20.7%]), and SEP-1 implementation was not associated with changes in level (OR, 0.94; 95% CI, 0.68-1.29) or trend (OR, 1.00; 95% CI, 0.97-1.04) for risk-adjusted short-term mortality rates. Conclusions and Relevance: In this cohort study, SEP-1 implementation was associated with an immediate increase in lactate testing rates, no change in already-increasing rates of broad-spectrum antibiotic use, and no change in short-term mortality rates for patients with suspected sepsis. Other approaches to decrease sepsis mortality may be warranted.

Impact of Risk Adjustment Using Clinical vs Administrative Data on Hospital Sepsis Mortality Comparisons.

BACKGROUND: A reliable risk-adjusted sepsis outcome measure could complement current national process metrics by identifying outlier hospitals and catalyzing additional improvements in care. However, it is unclear whether integrating clinical data into risk adjustment models identifies similar high- and low-performing hospitals compared with administrative data alone, which are simpler to acquire and analyze. METHODS: We ranked 200 US hospitals by their Centers for Disease Control and Prevention Adult Sepsis Event (ASE) mortality rates and assessed how rankings changed after applying (1) an administrative risk adjustment model incorporating demographics, comorbidities, and codes for severe illness and (2) an integrated clinical and administrative model replacing severity-of-illness codes with laboratory results, vasopressors, and mechanical ventilation. We assessed agreement between hospitals' risk-adjusted ASE mortality rates when ranked into quartiles using weighted kappa statistics (к). RESULTS: The cohort included 4 009 631 hospitalizations, of which 245 808 met ASE criteria. Risk-adjustment had a large effect on rankings: 22/50 hospitals (44%) in the worst quartile using crude mortality rates shifted into better quartiles after administrative risk adjustment, and a further 21/50 (42%) of hospitals in the worst quartile using administrative risk adjustment shifted to better quartiles after incorporating clinical data. Conversely, 14/50 (28%) hospitals in the best quartile using administrative risk adjustment shifted to worse quartiles with clinical data. Overall agreement between hospital quartile rankings when risk-adjusted using administrative vs clinical data was moderate (к = 0.55). CONCLUSIONS: Incorporating clinical data into risk adjustment substantially changes rankings of hospitals' sepsis mortality rates compared with using administrative data alone. Comprehensive risk adjustment using both administrative and clinical data is necessary before comparing hospitals by sepsis mortality rates.

Prevalence of Antibiotic-Resistant Pathogens in Culture-Proven Sepsis and Outcomes Associated With Inadequate and Broad-Spectrum Empiric Antibiotic Use.

Importance: Broad-spectrum antibiotics are recommended for all patients with suspected sepsis to minimize the risk of undertreatment. However, little is known regarding the net prevalence of antibiotic-resistant pathogens across all patients with community-onset sepsis or the outcomes associated with unnecessarily broad empiric treatment. Objective: To elucidate the epidemiology of antibiotic-resistant pathogens and the outcomes associated with both undertreatment and overtreatment in patients with culture-positive community-onset sepsis. Design, Setting, and Participants: This cohort study included 17 430 adults admitted to 104 US hospitals between January 2009 and December 2015 with sepsis and positive clinical cultures within 2 days of admission. Data analysis took place from January 2018 to December 2019. Exposures: Inadequate empiric antibiotic therapy (ie, ≥1 pathogen nonsusceptible to all antibiotics administered on the first or second day of treatment) and unnecessarily broad empiric therapy (ie, active against methicillin-resistant Staphylococcus aureus [MRSA]; vancomycin-resistant Enterococcus [VRE]; ceftriaxone-resistant gram-negative [CTX-RO] organisms, including Pseudomonas aeruginosa; or extended-spectrum ß-lactamase [ESBL] gram-negative organisms when none of these were isolated). Main Outcomes and Measures: Prevalence and empiric treatment rates for antibiotic-resistant organisms and associations of inadequate and unnecessarily broad empiric therapy with in-hospital mortality were assessed, adjusting for baseline characteristics and severity of illness. Results: Of 17 430 patients with culture-positive community-onset sepsis (median [interquartile range] age, 69 [57-81] years; 9737 [55.9%] women), 2865 (16.4%) died in the hospital. The most common culture-positive sites were urine (9077 [52.1%]), blood (6968 [40.0%]), and the respiratory tract (2912 [16.7%]). The most common pathogens were Escherichia coli (5873 [33.7%]), S aureus (3706 [21.3%]), and Streptococcus species (2361 [13.5%]). Among 15 183 cases in which all antibiotic-pathogen susceptibility combinations could be calculated, most (12 398 [81.6%]) received adequate empiric antibiotics. Empiric therapy targeted resistant organisms in 11 683 of 17 430 cases (67.0%; primarily vancomycin and anti-Pseudomonal ß-lactams), but resistant organisms were uncommon (MRSA, 2045 [11.7%]; CTX-RO, 2278 [13.1%]; VRE, 360 [2.1%]; ESBLs, 133 [0.8%]). The net prevalence for at least 1 resistant gram-positive organism (ie, MRSA or VRE) was 13.6% (2376 patients), and for at least 1 resistant gram-negative organism (ie, CTX-RO, ESBL, or CRE), it was 13.2% (2297 patients). Both inadequate and unnecessarily broad empiric antibiotics were associated with higher mortality after detailed risk adjustment (inadequate empiric antibiotics: odds ratio, 1.19; 95% CI, 1.03-1.37; P = .02; unnecessarily broad empiric antibiotics: odds ratio, 1.22; 95% CI, 1.06-1.40; P = .007). Conclusions and Relevance: In this study, most patients with community-onset sepsis did not have resistant pathogens, yet broad-spectrum antibiotics were frequently administered. Both inadequate and unnecessarily broad empiric antibiotics were associated with higher mortality. These findings underscore the need for better tests to rapidly identify patients with resistant pathogens and for more judicious use of broad-spectrum antibiotics for empiric sepsis treatment.

Membrane docking geometry of GRP1 PH domain bound to a target lipid bilayer: an EPR site-directed spin-labeling and relaxation study.

The second messenger lipid PIP(3) (phosphatidylinositol-3,4,5-trisphosphate) is generated by the lipid kinase PI3K (phosphoinositide-3-kinase) in the inner leaflet of the plasma membrane, where it regulates a broad array of cell processes by recruiting multiple signaling proteins containing PIP(3)-specific pleckstrin homology (PH) domains to the membrane surface. Despite the broad importance of PIP(3)-specific PH domains, the membrane docking geometry of a PH domain bound to its target PIP(3) lipid on a bilayer surface has not yet been experimentally determined. The present study employs EPR site-directed spin labeling and relaxation methods to elucidate the membrane docking geometry of GRP1 PH domain bound to bilayer-embedded PIP(3). The model target bilayer contains the neutral background lipid PC and both essential targeting lipids: (i) PIP(3) target lipid that provides specificity and affinity, and (ii) PS facilitator lipid that enhances the PIP(3) on-rate via an electrostatic search mechanism. The EPR approach measures membrane depth parameters for 18 function-retaining spin labels coupled to the PH domain, and for calibration spin labels coupled to phospholipids. The resulting depth parameters, together with the known high resolution structure of the co-complex between GRP1 PH domain and the PIP(3) headgroup, provide sufficient constraints to define an optimized, self-consistent membrane docking geometry. In this optimized geometry the PH domain engulfs the PIP(3) headgroup with minimal bilayer penetration, yielding the shallowest membrane position yet described for a lipid binding domain. This binding interaction displaces the PIP(3) headgroup from its lowest energy position and orientation in the bilayer, but the headgroup remains within its energetically accessible depth and angular ranges. Finally, the optimized docking geometry explains previous biophysical findings including mutations observed to disrupt membrane binding, and the rapid lateral diffusion observed for PIP(3)-bound GRP1 PH domain on supported lipid bilayers.

Functional characterization of the re-face loop spanning residues 536-541 and its interactions with the cofactor in the flavin mononucleotide-binding domain of flavocytochrome P450 from Bacillus megaterium.

Flavocytochrome P450BM-3, a bacterial monooxygenase, contains a flavin mononucleotide-binding domain bearing a strong structural homology to the bacterial flavodoxin. The flavin mononucleotide (FMN) serves as the one-electron donor to the heme iron, but in contrast to the electron transfer mechanism of mammalian cytochrome P450 reductase, the FMN semiquinone state is not thermodynamically stable and appears transiently as the anionic rather than the neutral form. A unique loop region comprised of residues (536)Y-N-G-H-P-P(541), which forms a type I' reverse turn and provides several interactions with the FMN isoalloxazine ring, was targeted in this study. Nuclear magnetic resonance studies support the presence of a strong hydrogen bond between the backbone amide of Asn537 and FMN N5, the anionic ionization state of the hydroquinone, and for a change in the hybridization state of the N5 upon reduction. Replacement of Tyr536, which flanks the flavin ring, with a basic residue (histidine or arginine) did not significantly influence the redox properties of the FMN or the accumulation of the anionic semiquinone. The central residues of the type I' turn (Asn-Gly) were replaced with various combinations of glycine and alanine as a means of altering the turn and its interactions. Gly538 was found to be crucial in maintaining the type I' turn conformation of the loop and the strong H-bonding interaction at N5. The functional role of the tandem Pro-Pro sequence which anchors and possible "rigidifies" the loop was investigated through alanine replacements. Despite changes in the stabilities of the oxidized and hydroquinone redox states of the FMN, none of the replacements studied significantly altered the two-electron midpoint potentials. Pro541 does contribute to some degree to the strength of the N5 interaction and the formation of the anionic semiquinone. Unlike that of the flavodoxin, it would appear that the conformation of the FMN rather than the loop changes in response to reduction in this flavoprotein.

Effect of the Insertion of a Glycine Residue into the Loop Spanning Residues 536-541 on the Semiquinone State and Redox Properties of the Flavin Mononucleotide-Binding Domain of Flavocytochrome P450BM-3 from Bacillus megaterium.

Despite sharing sequence and structural similarities with other diflavin reductases such as NADPH-cytochrome P450 reductase (CPR) and nitric oxide synthase, flavocytochrome P450BM-3 displays some unique redox and electron transferring properties, including the inability to thermodynamically stabilize the neutral semiquinone (SQ) state of the flavin mononucleotide (FMN) cofactor. Rather, the anionic SQ species is only transiently formed during rapid reduction. Why is this? The absence of a conserved glycine residue and, as a consequence, the shorter and less flexible cofactor-binding loop in P450BM-3 represents a notable difference from other diflavin reductases and the structurally related flavodoxin. This difference may facilitate the formation of a strong hydrogen bond between backbone amide NH group of Asn537 and N5 of the oxidized FMN, an interaction not found in the other proteins. In the flavodoxin, the conserved glycine residue plays a crucial role in a redox-linked conformational change that contributes to the thermodynamic stabilization of the neutral SQ species of the FMN through the formation of a hydrogen bond with the N5H group of the flavin. In this study, a glycine residue was inserted after Tyr536 in the loop within the isolated FMN-binding domain as well as the diflavin reductase domain of P450BM-3, a position equivalent to Gly141 in human CPR. As a result, the insertion variant was observed to accumulate the neutral form of the FMN SQ species much like CPR. The midpoint potential for the SQ/HQ couple decreased by 68 mV, while that for the OX/SQ couple remained unchanged. (15)N NMR data provide evidence of the disruption of the hydrogen bond between the backbone amide group of Asn537 and the N5 atom in the oxidized state of the FMN. Molecular models suggest that the neutral FMN SQ could be stabilized through hydrogen bonding with the backbone carbonyl group of the inserted glycine residue in a manner similar to that of CPR and the flavodoxin. The insertion of the glycine at the same location within the diflavin domain resulted in a purified protein that retained nearly stoichiometric levels of bound FAD but tended to lose the FMN cofactor. This preparation retained one-third of the ferricyanide reductase activity but <1% of the cytochrome c reductase activity of the wild type. However, the insertion variant reconstituted with FMN regained nearly half of the wild-type cytochrome c reductase activity. These results demonstrate the importance of the unique structural characteristics of the shorter loop in P450BM-3 in establishing the unique redox properties of the FMN in this protein but not its general cytochrome reductase activity.