Descriptive evaluation of patients receiving one-time intravenous vancomycin doses at a large academic medical center emergency department.

BACKGROUND: Intravenous (IV) vancomycin is commonly used to treat a variety of infections caused by methicillin-resistant Staphylococcus aureus (MRSA). The practice of administering a single dose of IV vancomycin prior to emergency department (ED) discharge may be clinically ineffective and foster antimicrobial resistance. Furthermore, this practice introduces an unnecessary infection risk along with preventable adverse effects while potentially increasing ED length of stay (LOS). There is a paucity of literature identifying patient characteristics and objective findings in this patient population, which may foster future antimicrobial stewardship initiatives in the ED. METHODS: This was a single-center, retrospective, descriptive analysis of adult patients seen in the ED between January 2020 and January 2023 who received a single dose of IV vancomycin and were subsequently discharged from the ED without hospital admission. Information was collected on patient demographics and select comorbidities, vancomycin indication and dosing, ED LOS, initial vitals and labs, concomitant antibiotics administered, culture results, 30-day return ED visits and admissions, and antibiotics prescribed at ED discharge. RESULTS: A total of 295 patients met inclusion criteria. A total of 32.1% of patients met SIRS criteria. The most commonly selected order indication for IV vancomycin was "skin and skin structure infection" (41%). A total of 86.1% of patients received concomitant antibiotics in the ED and only 54.6% of patients were prescribed oral antibiotics at ED discharge. A total of 80% of patients had at least one culture obtained during the ED visit. In those who had at least one culture obtained, 78.4% of patients had negative cultures and 4.2% of patients had MRSA positive cultures, with MRSA skin cultures being the most common (3.1%). Return ED visits and admissions within 30 days were not statistically significantly different between patients who did and did not receive oral antibiotics at ED discharge. CONCLUSIONS: Despite a lack of clinical efficacy reported in prior literature and the potential risks, administration of a one-time dose of IV vancomycin prior to ED discharge is commonly encountered in clinical practice. There are opportunities for enhanced antimicrobial stewardship related to IV vancomycin use in the ED. Areas of future focus include the utilization of oral antimicrobials when clinically appropriate, particularly for skin and soft tissue infections, and clarification of antibiotic allergies.

Characterization of Febrile Neutropenia Management in Children With Malignancies: A Single-Center Evaluation.

OBJECTIVE: Current recommendations for febrile neutropenia (FN) include initiation of broad-spectrum antibiotics without clear indications of when or how to de-escalate or target therapy, especially in those without microbiologically defined bloodstream infections (MD-BSIs). The purpose of this study is to characterize a pediatric FN population, FN management, and identify the proportion of patients with MD-BSI. METHODS: This study was a single-center, retrospective chart review of patients admitted to the University of North Carolina Children's Hospital between January 1, 2016, and December 31, 2019, with a diagnosis of FN. RESULTS: There were 81 unique encounters included in this study. MD-BSI was the etiology of fever in 8 FN episodes (9.9%). The most common empiric antibiotic regimen was cefepime (62%) followed by cefepime and vancomycin (25%). The most common de-escalation type was the discontinuation of vancomycin (83.3%), and the most common type of escalation was the addition of vancomycin (50%). The median antibiotic total duration in patients without MDI-BSI was 3 days (IQR, 5-9). CONCLUSIONS: In this single-center, retrospective review, most FN episodes were not due to an MD-BSI. There were inconsistencies in practice of when discontinuation of antibiotic therapy occurred in patients without MD-BSI. De-escalation or cessation of antibiotic therapy before neutropenia resolution did not result in any documented complication. These data suggest a role for implementing an institutional guideline to improve consistency in antimicrobial use in pediatric patients with febrile neutropenia.

Population Pharmacokinetics of Posaconazole in Immune-Compromised Children and Assessment of Target Attainment in Invasive Fungal Disease.

BACKGROUND AND OBJECTIVE: Posaconazole (PSZ) is a triazole antifungal for the management of invasive fungal disease (IFD) in adults and children. Although PSZ is available as an intravenous (IV) solution, oral suspension (OS) and delayed-release tablets (DRTs), OS is the preferred formulation for pediatric use because of potential safety concerns associated with an excipient in the IV formulation and difficulty in swallowing intact tablets by children. However, poor biopharmaceutical characteristics of the OS formulation leads to an unpredictable dose-exposure profile of PSZ in children, potentially risking therapeutic failure. The goal of this study was to characterize the population pharmacokinetics (PK) of PSZ in immunocompromised children and assess therapeutic target attainment. METHODS: Serum concentrations of PSZ were collected retrospectively from records of hospitalized patients. A population PK analysis was performed in a nonlinear mixed-effects modeling framework with NONMEM (v7.4). The PK parameters were scaled to body weight, then potential covariate effects were assessed. The final PK model was used to evaluate recommended dosing schemes through simulation of target attainment (as a percentage of the population having steady-state trough concentrations above the recommended target) using Simulx (v2021R1). RESULTS: Repeated measurement data of 202 serum concentrations of total PSZ were acquired from 47 immunocompromised patients between 1 and 21 years of age receiving PSZ either intravenously or orally, or both. A one-compartment PK model with first-order absorption and linear elimination best fit the data. The estimated absolute bioavailability (95% confidence interval) for suspension (Fs) was 16% (8-27%), which was significantly lower than the reported tablet bioavailability (Ft) [67%]. Fs was reduced by 62% and 75% upon concomitant administration with pantoprazole (PAN) and omeprazole (OME), respectively. Famotidine resulted in a reduction of Fs by only 22%. Both fixed dosing and weight-based adaptive dosing provided adequate target attainment when PAN or OME were not coadministered with the suspension. CONCLUSIONS: The results of this study revealed that both fixed and weight-based adaptive dosing schemes can be appropriate for target attainment across all PSZ formulations, including suspension. Additionally, covariate analysis suggests that concomitant proton pump inhibitors should be contraindicated during PSZ suspension dosing.

Evaluation of early de-escalation of empiric antimicrobial therapy in acute leukemia patients with febrile neutropenia at a large academic medical center.

INTRODUCTION: Recent trials have shown early de-escalation of empiric antimicrobial therapy (EAT) in febrile neutropenia has led to less adverse effects with no difference in patient mortality. In 2019, our institution adjusted internal guidelines to de-escalate EAT after 7 days of intravenous anti-pseudomonal therapy in patients with signs of clinical recovery from febrile neutropenia and no evidence of infection. METHODS: This was a retrospective, single-center, observational, cohort study. Eligible patients were adults with acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL) who received induction chemotherapy and developed febrile neutropenia without documented infection. Patients were separated based on EAT duration: ≤ 9 days and > 9 days. Empiric antimicrobial therapy was defined as the initiation of an anti-pseudomonal beta-lactam. The primary outcome was the difference in number of EAT-free days. Secondary outcomes included fever recurrence, ICU admissions, fever duration, infections post de-escalation, and Clostridioides difficile infection (CDI). RESULTS: Forty-four encounters met inclusion. The EAT ≤ 9 days group had 7 more EAT-free days compared to the EAT > 9 days group (p < 0.001). No between-group differences were identified in terms of fever after EAT discontinuation (p = 0.335), ICU admission (p = 0.498), or CDI (p = 0.498). The EAT > 9 days group experienced longer initial fever (p < 0.001) and received addition of resistant Gram-positive coverage (p = 0.014). More patients receiving EAT > 9 days had a diagnosis of AML (p = 0.001). CONCLUSIONS: Shorter EAT duration did not lead to worse outcomes in patients with AML or ALL who received induction chemotherapy and developed febrile neutropenia without a documented infection source.

Evaluation of Posaconazole Dosing in Children and Young Adults: A Single-Center Review.

OBJECTIVE: Initial posaconazole dosing regimens in children often do not achieve target concentrations, and data continue to support the need for higher initial dosing regimens. The objective of this study is to contribute to the current data regarding suboptimal posaconazole dosing in pediatric patients by retrospectively observing dosing strategies and subsequent drug concentrations. METHODS: This study was conducted at a single institution in 27 patients aged 1 to 21 years. Patients who were initiated on any formulation of posaconazole for prophylaxis or treatment while admitted to the hospital were included. The primary outcome was to determine the percentage of pediatric patients who achieved the targeted trough concentration using their initial posaconazole dosing regimen. Secondary outcomes included percentage of patients who experienced a breakthrough invasive fungal infection (IFI), percentage of patients with elevated liver function tests (LFTs), and discontinuation for any reason. RESULTS: There were 15 patients (55.5%) who reached desired trough serum concentration after the initial dosing regimen. The number of dose modifications to achieve the desired trough ranged from 1 to 3. Most patients received delayed-release tablets (n = 17), and the average doses for reaching prophylactic and treatment trough concentrations were 6.1 mg/kg/day and 11 mg/kg/day, respectively. There were 2 patients (7.4%) who experienced breakthrough IFI. Overall, 5 patients developed elevated LFTs and 7 patients discontinued treatment early. CONCLUSIONS: The results describe a single population of pediatric patients, of whom 55% were able to achieve target trough concentrations of posaconazole with the initial dosing strategy used.

Energy Expenditure in Critically Ill Adult Patients With Acute Brain Injury: Indirect Calorimetry vs. Predictive Equations.

Introduction: Predictive equations (PE) are used in lieu of indirect calorimetry (IC) due to cost and limited resources; however, these equations may not be as accurate as IC in estimating resting energy expenditure (REE) in critically ill patients, putting them at risk of malnutrition. The purpose of this study is to compare predicted and measured energy expenditure (MEE) in critically ill adults with acute brain injury. Materials and Methods: This was a retrospective review of adult patients admitted to the Neurosciences ICU with acute brain injury between May 1st, 2014 and April 1st, 2016 who had IC performed. The Harris Benedict (HBE), Penn State University, and Mifflin St Jeor (MSJ) PE were used in comparison to IC results. Subgroup analyses stratified patients based on BMI and type of acute brain injury. Results: One hundred and forty-four patients met inclusion criteria. Comparing predicted and MEE found no significant difference (p = 0.1). High degrees of interpatient variability were discovered, with standard deviations ranging from 17 to 29% of each PE. Pearson's correlations indicated weak associations when HBE, Penn State, and MSJ were individually compared to MEE (r = 0.372, 0.409, and 0.372, respectively). A significant difference was found between predicted and MEE in patients with a BMI < 30 kg/m2 (p < 0.01) and in those with aneurysmal subarachnoid hemorrhage (p < 0.01). Discussion: Due to interpatient variability that exists among REE of critically ill patients with acute brain injury, IC should be used when feasible.

Optical fiber-coupled ocular spectrometer for measurement of drug concentration in the anterior eye--applications in pharmaceuticals research.

This paper describes in detail a novel optoelectronic system designed to measure drug absorption in the anterior segment of the eye following topical application of drug formulations. This minimally invasive measurement technique offers both a method for determining drug concentration in human eyes, and demonstrates an alternative to current testing processes in model animals, which require paracentesis of the anterior chamber of the eye. The optoelectronic technique can be used with formulations, which possess appropriate spectral characteristics, namely unique absorption or fluorescence spectra. Preliminary experiments using our measurement system have been performed in rabbit and man, where we have been successful in achieving the direct measurement of topically applied brimonidine, an alpha-2 agonist used in the treatment of glaucoma. This demonstrates the feasibility of performing real-time, in vivo testing of ophthalmic drug formulations in the eye of human test subjects. We further demonstrate the novel application of the optoelectronic system for detection of topically applied UV-absorbing compounds in rabbit cadaver eyes, with a view to evaluating potential ocular sunscreen formulations. In summary, this method can be applied for the rapid comparison of the penetration of different drug formulations into the anterior eye at greatly reduced cost and time.

Ascorbate elevates perfusion pressure in the bovine extraocular long posterior ciliary artery: role of endothelium-derived hyperpolarizing factor (EDHF).

Ascorbate blocks agonist-induced, endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation in the bovine perfused ciliary artery and this is associated with a rise in perfusion pressure. We now report the origins of this ascorbate-induced rise in perfusion pressure. In segments of ciliary artery perfused at 2.5 ml/min, the addition of ascorbate (10-150 microM) enhanced U46619-induced perfusion pressure. Ascorbate produced no enhancement in the absence of U46619, suggesting that its effects resulted not from a constrictor action but through removal of a tonic vasodilator influence. Experiments revealed the endothelial source of this vasodilator influence, and EDHF, but not nitric oxide or prostanoids, appeared to be involved. The ascorbate-induced enhancement of vasoconstrictor tone was not seen in a static myograph or in segments perfused at low rates of flow, but was seen at flow rates of 2.5 ml(-1) and above. We conclude that ascorbate augments vasoconstrictor tone through inhibition of flow-induced EDHF activity.

Biphasic neurogenic vasodilatation in the bovine intraocular long posterior ciliary artery: involvement of nitric oxide and an additional unidentified neurotransmitter.

We have investigated the neurogenic factors inducing relaxation in the intraocular segment of the bovine long posterior ciliary artery. In precontracted vessels, electrical field stimulation (EFS, 0.5-128 Hz, 10 s trains) in the presence of guanethidine (30 microM) evoked biphasic relaxation: optimal relaxation for the first and second components occurred at 10 and 50 s, respectively. The first component, but not the second, was abolished by L-NAME (100 microM) or ODQ (3 microM). Relaxation to exogenous CGRP (0.1-300 nM) was inhibited by the CGRP antagonist, CGRP(8-37) (1-5 microM), but neither component of neurogenic relaxation was affected. Preincubation with the sensory nerve excitotoxin, capsaicin (1 microM), had no effect on either the first or second components of neurogenic relaxation. Substance P (0.1 nM-0.1 microM) induced relaxation, but rapid and complete desensitisation occurred within minutes. Neither desensitisation to substance P (0.1 microM) nor incubation with the NK(1) antagonist, L-733,060 (0.3 microM), had any effect on the first or second components of neurogenic relaxation.VIP (0.1 nM-0.3 microM) induced relaxation and this was followed by substantial desensitisation. Neither desensitisation to VIP (0.6 microM) nor treatment with the protease, alpha-chymotrypsin (10 U ml(-1)), had any effect on the first or second components of neurogenic relaxation. The results indicate that nitric oxide mediates the first component of neurogenic relaxation in the bovine intraocular ciliary artery. The neurotransmitter mediating the second component remains to be determined but is unlikely to be CGRP, substance P or VIP.

Requirement for flow in the blockade of endothelium-derived hyperpolarizing factor (EDHF) by ascorbate in the bovine ciliary artery.

We previously reported that ascorbate inhibits endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation in the bovine perfused ciliary circulation and rat perfused mesentery, but not in rings of bovine or porcine coronary artery. In this study, we have compared the ability of ascorbate to inhibit EDHF-mediated vasodilatation in a single vessel, the bovine long posterior ciliary artery, when perfused and when mounted as rings in a myograph. Both in segments perfused at a flow rate of 2.5 ml min(-1) and in rings mounted in a myograph, bradykinin and acetylcholine each induced vasodilator responses that were mediated jointly by EDHF and nitric oxide, as revealed by their respective blocking agents, apamin/charybdotoxin, and L-NAME. Ascorbate (50 and 150 microm) induced a time (max at 2-3 h)-dependent inhibition of the EDHF-mediated component of vasodilatation to bradykinin or acetylcholine in perfused segments, but not in rings. Ascorbate (50 microm) failed to inhibit bradykinin-induced vasodilatation at a flow rate of 1.25 ml min(-1) or below, but produced graded blockade at the higher flow rates of 2.5 and 5 ml min(-1). Furthermore, using a pressure myograph where pressure and flow were independently controlled, it was confirmed that the inhibitory action of ascorbate (150 microm) was directly related to flow per se and not any associated changes in pressure. Thus, we have shown in the bovine ciliary artery that ascorbate inhibits EDHF-mediated vasodilatation under conditions of flow but not in a static myograph. The mechanism by which flow renders EDHF susceptible to inhibition by ascorbate remains to be determined.

Evaluation of potassium ion as the endothelium-derived hyperpolarizing factor (EDHF) in the bovine coronary artery.

1. This study explored the role of the potassium ion in endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation in the bovine coronary artery. 2. Bradykinin-induced, EDHF-mediated vasodilatation was blocked by the Na(+)-K(+) ATPase inhibitor, ouabain (1 micro M), in a time-dependent manner, with maximal blockade seen after 90 min. In contrast, the K(IR) channel inhibitor, Ba(2+) (30 micro M), had no effect. 3. When the potassium content of the bathing solution was increased in a single step from 5.9 to 7-19 mM, powerful vasodilatation (max. 75.9+/-3.6%) was observed. Vasodilatation was transient and, consequently, cumulative addition of potassium produced little vasodilatation, with vasoconstriction predominating at the higher concentrations. 4. The magnitude of potassium-induced vasodilatation was similar in endothelium-containing and endothelium-denuded rings, and was unaffected by Ba(2+) (30 micro M), but abolished by ouabain (1 micro M). 5. Ouabain (1 micro M, 90 min) powerfully blocked bradykinin-induced, nitric oxide-mediated vasodilatation as well as that induced by the nitrovasodilator, glyceryl trinitrate, but that induced by the K(ATP) channel opener, levcromakalim, was hardly affected. 6. Thus, activation of Na(+)-K(+) ATPase is likely to be involved in the vasodilator responses of the bovine coronary artery to both nitric oxide and EDHF. These findings, together with the ability of potassium to induce powerful, ouabain- but not Ba(2+)-sensitive, endothelium-independent vasodilatation, are consistent with this ion contributing to the EDHF response in this tissue.

Differential effects of ascorbate on endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation in the bovine ciliary vascular bed and coronary artery.

1. The ability of ascorbate to inhibit endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation was compared in the bovine perfused ciliary vascular bed and isolated rings of coronary artery. 2. Acetylcholine-induced, EDHF-mediated vasodilatation of the ciliary circulation was blocked following inclusion of ascorbate (50 micro M, 120 min) in the perfusion fluid. The blockade was highly selective since ascorbate had no effect on the vasodilator actions of the K(ATP) channel opener, levcromakalim, nor on the tonic vasodepressor action of basally released nitric oxide. 3. The possibility that concentration of ascorbate by the ciliary body was a prerequisite for blockade to occur was ruled out, since EDHF was still blocked when the anterior and posterior chambers were continuously flushed with Krebs solution or when both the aqueous and vitreous humour were drained. 4. Ascorbate at 50 micro M failed to affect bradykinin- or acetylcholine-induced, EDHF-mediated vasodilatation in rings of bovine coronary artery. Raising the concentration to 3 mM did produce blockade of EDHF, but this was nonselective, since vasodilator responses to endothelium-derived nitric oxide were also inhibited. 5. Thus, ascorbate (50 micro M) is not a universal blocker of EDHF. Whether its ability to block in the bovine ciliary circulation, but not in the coronary artery, is due to differences in the nature of EDHF at the two sites, differences in vessel size (resistance arterioles versus conduit artery), the presence or absence of flow, or to some other factor remains to be determined.

Effects of ion transport and channel-blocking drugs on aqueous humor formation in isolated bovine eye.

PURPOSE: To investigate the role of active chloride secretion by the ciliary epithelium in the formation of aqueous humor (AH), by using the in vitro perfused eye. METHODS: Bovine eyes collected from an abattoir were cannulated through the ophthalmic artery and perfused with oxygenated Krebs' solution at 37 degrees C. Aqueous humor formation (AHF) was measured by the fluorescein-dilution technique. Drugs were added to the perfusate and/or to the anterior chamber. RESULTS: NaK-adenosine triphosphatase (ATPase) inhibitor, ouabain (1.0 mM), produced a significant reduction in AHF by 46% and 42% when added to the stromal or aqueous side, respectively. When added to both sides (1.0 mM), it produced a reduction of 61%. Bumetanide (0.1 mM), a specific inhibitor of Na-K-2Cl cotransport, and furosemide (0.1 mM), a nonspecific anion transport inhibitor, produced 35% and 45% reductions when applied to the stromal side. DIDS (0.001-0.1 mM), which is believed to inhibit the Cl-HCO(3) exchanger, Na-HCO(3) cotransporter, and chloride channel, produced a dose-dependent reduction when added to the stromal side. The inhibition was 55% by the highest concentration used. 5-Nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB; 0.1 mM), a chloride channel blocker in the nonpigmented cells, produced a 25% reduction when applied to the aqueous side. Acetazolamide (0.1 mM), a carbonic anhydrase inhibitor, applied to the stromal side, produced 31% reduction. CONCLUSIONS: At least 60% of the AH is formed by active secretion in bovine eyes. Transport of anions through the ciliary epithelium (CE), particularly the chloride ion, plays a crucial role in AHF.

Ascorbate blocks endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation in the bovine ciliary vascular bed and rat mesentery.

1. The effects of ascorbate were assessed on vasodilatation mediated by endothelium-derived hyperpolarizing factor (EDHF) in the ciliary vascular bed of the bovine isolated perfused eye and in the rat isolated perfused mesenteric arterial bed. 2. In the bovine eye, EDHF-mediated vasodilator responses induced by acetylcholine or bradykinin were powerfully blocked when ascorbate (50 microM) was included in the perfusion medium for at least 120 min; with acetylcholine a normally-masked muscarinic vasoconstrictor response was also uncovered. 3. The blockade of EDHF-mediated vasodilatation by ascorbate was time-dependent (maximum blockade at 120 min) and concentration-dependent (10 - 150 microM). 4. Ascorbate (50 microM) also blocked acetylcholine-induced, EDHF-mediated vasodilator responses in the rat mesenteric arterial bed in a time-dependent manner (maximum blockade at 180 min). 5. The ability of ascorbate to block EDHF-mediated vasodilatation is likely to result from its reducing properties, since this action was mimicked in the bovine eye by two other reducing agents, namely, N-acetyl-L-cysteine (1 mM) and dithiothreitol (100 microM), but not by the redox-inactive analogue, dehydroascorbate (50 microM). 6. In conclusion, concentrations of ascorbate present in normal plasma block EDHF-mediated vasodilator responses in the bovine eye and rat mesentery. The mechanism and physiological consequences of this blockade remain to be determined.