Antiplatelet therapy for Staphylococcus aureus bacteremia: Will it stick?

Staphylococcus aureus bacteremia (SAB) remains a clinically challenging infection despite extensive investigation. Repurposing medications approved for other indications is appealing as clinical safety profiles have already been established. Ticagrelor, a reversible adenosine diphosphate receptor antagonist that prevents platelet aggregation, is indicated for patients suffering from acute coronary syndrome (ACS). However, some clinical data suggest that patients treated with ticagrelor are less likely to have poor outcomes due to S. aureus infection. There are several potential mechanisms by which ticagrelor may affect S. aureus virulence. These include direct antibacterial activity, up-regulation of the innate immune system through boosting platelet-mediated S. aureus killing, and prevention of S. aureus adhesion to host tissues. In this Pearl, we review the clinical data surrounding ticagrelor and infection as well as explore the evidence surrounding these proposed mechanisms of action. While more evidence is needed before antiplatelet medications formally become part of the arsenal against S. aureus infection, these potential mechanisms represent exciting pathways to target in the host/pathogen interface.

Rapid antimicrobial resistance detection methods for bloodstream infection in solid organ transplantation: Proposed clinical guidance, unmet needs, and future directions.

Recent advances in antimicrobial resistance detection have spurred the development of multiple assays that can accurately detect the presence of bacterial resistance from positive blood cultures, resulting in faster institution of effective antimicrobial therapy. Despite these advances, there are limited data regarding the use of these assays in solid organ transplant (SOT) recipients and there is little guidance on how to select, implement, and interpret them in clinical practice. We describe a practical approach to the implementation and interpretation of these assays in SOT recipients using the best available data and expert opinion. These findings were part of a consensus conference sponsored by the American Society of Transplantation held on December 7, 2021 and represent the collaboration between experts in transplant infectious diseases, pharmacy, antimicrobial and diagnostic stewardship, and clinical microbiology. Areas of unmet need and recommendations for future investigation are also presented.

Analysis of the use of empiric antimicrobial prophylaxis for temporary cardiac devices at a large academic medical center.

INTRODUCTION: Varying rates of access site infections with temporary percutaneous cardiac devices have been reported in the literature. The purpose of this study is to determine the impact of a change in institutional practice in utilizing antimicrobial prophylaxis to prevent access site infections in patients with these devices. METHODS: This observational, pre-post implementation analysis evaluated the benefit of prophylactic antimicrobial therapy in adult patients with temporary percutaneous cardiac devices admitted to cardiac intensive care units. Patients in the pre-cohort received prophylactic antibiotics for the duration of device insertion. Patients in the post-cohort received a single dose of intravenous antibiotics for veno-arterial extracorporeal membrane oxygenation (VA-ECMO) or Impella® 5.5 device placement, and no antimicrobial prophylaxis for all other devices placed. The primary endpoint was the incidence of definitive access site infection. Secondary endpoints included the incidence of Clostridium difficile infection and initiation of broad-spectrum antibiotics. RESULTS: Fifty patients in the pre-cohort and 45 patients in the post-cohort were evaluated. Devices included intra-aortic balloon pumps, VA-ECMO, Impella® CP and Impella® 5.5. The median duration of device insertion was four days. No significant difference in the primary outcome was seen between the two groups. A significant reduction in prophylactic antimicrobial utilization and total days of antimicrobial exposure was observed in the post-implementation cohort. CONCLUSION: Based on the results of our study, the implemented guideline reduces the utilization of antimicrobial prophylaxis in patients with temporary percutaneous cardiac devices and does not result in an increased rate of infections.

A consensus conference to define the utility of advanced infectious disease diagnostics in solid organ transplant recipients.

The last decade has seen an explosion of advanced assays for the diagnosis of infectious diseases, yet evidence-based recommendations to inform their optimal use in the care of transplant recipients are lacking. A consensus conference sponsored by the American Society of Transplantation (AST) was convened on December 7, 2021, to define the utility of novel infectious disease diagnostics in organ transplant recipients. The conference represented a collaborative effort by experts in transplant infectious diseases, diagnostic stewardship, and clinical microbiology from centers across North America to evaluate current uses, unmet needs, and future directions for assays in 5 categories including (1) multiplex molecular assays, (2) rapid antimicrobial resistance detection methods, (3) pathogen-specific T-cell reactivity assays, (4) next-generation sequencing assays, and (5) mass spectrometry-based assays. Participants reviewed and appraised available literature, determined assay advantages and limitations, developed best practice guidance largely based on expert opinion for clinical use, and identified areas of future investigation in the setting of transplantation. In addition, attendees emphasized the need for well-designed studies to generate high-quality evidence needed to guide care, identified regulatory and financial barriers, and discussed the role of regulatory agencies in facilitating research and implementation of these assays. Findings and consensus statements are presented.

Successful use of azithromycin for Escherichia coli-associated renal allograft malakoplakia: a report of two cases.

Malakoplakia is a chronic granulomatous disease associated with incomplete clearance of bacterial pathogens. A multimodal approach to therapy includes antimicrobials with intracellular activity, reduction in immunosuppression, and debulking of lesions. Azithromycin has an intracellular mechanism of action and enhanced Gram-negative activity compared to other macrolides. Despite some in vitro data to support its use, there are no clinical breakpoints or epidemiological cut-off values for most Enterobacterales from the European Committee on Antimicrobial Susceptibility Testing (EUCAST) or the Clinical and Laboratory Standards Institute (CLSI). We present two cases, previously unreported, of Escherichia coli associated renal allograft malakoplakia successfully treated with azithromycin.

Therapeutic drug monitoring of flucytosine in a cardiac transplant patient receiving continuous veno-venous hemofiltration and intermittent hemodialysis: A case report.

Invasive candidiasis is one of the common infections in solid organ transplant recipients. Guidelines recommend echinocandins or liposomal amphotericin with consideration of flucytosine (5-fluorocytosine; 5-FC) as synergistic therapy for treatment of select deep-seated Candida infections, including complex endovascular infections. Flucytosine undergoes extensive renal elimination; however, optimal dosing in patients with renal impairment, or those requiring renal replacement therapy (RRT), is not well-established. We describe a case of a 60-year old female who underwent orthotopic heart transplant complicated by Candida parapsilosis complex fungemia with mediastinitis and development of end-stage renal disease requiring RRT. Flucytosine therapeutic drug monitoring was performed on continuous veno-venous hemofiltration (CVVH) and intermittent hemodialysis (iHD) to guide appropriate dosing. Our results support 5-FC doses of 25 mg/kg daily while undergoing CVVH with a low fluid replacement rate and 21 mg/kg post-iHD or 17 mg/kg daily while receiving thrice weekly iHD.

Assessment and Optimization of the Empiric Treatment of Urinary Tract Infections in an Academic Emergency Department Observation Unit.

BACKGROUND: Poor adherence to evidence-based guidelines and overuse of broad-spectrum antibiotics has been noted in the emergency department (ED). There is limited evidence on guideline-congruent empiric therapy for urinary tract infections (UTIs) and uropathogen susceptibilities in the ED observation unit (EDOU). OBJECTIVE: The primary objective was to evaluate the prescribing patterns for the empiric treatment of UTI in the EDOU. Secondary objectives were to analyze uropathogen susceptibilities in the EDOU and implement an algorithm for the empiric treatment of UTI. METHODS: This study retrospectively reviewed adult patients who received empiric UTI treatment in the EDOU from January 1, 2018 to April 1, 2018. Eligible patients were categorized as having either uncomplicated or complicated cystitis, or pyelonephritis based on their clinical diagnosis. Antimicrobial therapy was evaluated in accordance with national practice guidelines, institutional guidelines, and local antimicrobial susceptibility patterns. RESULTS: Patients with uncomplicated or complicated cystitis (n = 115) were provided guideline-congruent empiric treatment in 87% of cases. Patients with pyelonephritis (n = 35) were provided guideline-congruent empiric treatment in 57% of cases. Susceptibility patterns of uropathogens isolated from this patient sample differed slightly from the institutional antibiogram, notably depicting a lower Escherichia coli susceptibility rate. Fluoroquinolones were prescribed for a longer than recommended duration in 18 patients (60%). CONCLUSIONS: The majority of patients in this study were provided guideline-congruent empiric therapy. Nevertheless, there are opportunities to optimize empiric UTI treatment and improve antibiotic stewardship in the EDOU.

Therapeutic drug concentrations of isavuconazole following the administration of isavuconazonium sulfate capsules via gastro-jejunum tube: A case report.

Invasive fungal infections are a common complication in immunocompromised patients, such as organ transplant recipients. Isavuconazole is a broad-spectrum azole antifungal for the treatment of aspergillosis and mucormycosis. The package insert for isavuconazole recommends against opening the capsule for administration through enteral feeding tubes. We describe the case of a 68-year-old man with a complex post-lung transplant course receiving isavuconazole for presumed invasive aspergillosis (bronchial alveolar lavage galactomannan index of >3.75) therapy administered through a gastrostomy-jejunostomy tube (G-J tube). Therapeutic drug monitoring was performed to ensure appropriate absorption. Peak and trough concentrations were measured in the early and late phases of the treatment course and resulted in trough levels of 2.7 mcg/mL and 4.0 mcg/mL, which is consistent with previously published trough concentrations of isavuconazole when the capsule was administered intact. This case report suggests that opening isavuconazole capsules and administration through a G-J tube results in appropriate absorption and serum drug levels comparable to intact capsules.

Soluble guanylyl cyclase is a critical regulator of migraine-associated pain.

Background Nitric oxide (NO) has been heavily implicated in migraine. Nitroglycerin is a prototypic NO-donor, and triggers migraine in humans. However, nitroglycerin also induces oxidative/nitrosative stress and is a source of peroxynitrite - factors previously linked with migraine etiology. Soluble guanylyl cyclase (sGC) is the high affinity NO receptor in the body, and the aim of this study was to identify the precise role of sGC in acute and chronic migraine. Methods We developed a novel brain-bioavailable sGC stimulator (VL-102), and tested its hyperalgesic properties in mice. We also determined the effect of VL-102 on c-fos and calcitonin gene related peptide (CGRP) immunoreactivity within the trigeminovascular complex. In addition, we also tested the known sGC inhibitor, ODQ, within the chronic nitroglycerin migraine model. Results VL-102-evoked acute and chronic mechanical cephalic and hind-paw allodynia in a dose-dependent manner, which was blocked by the migraine medications sumatriptan, propranolol, and topiramate. In addition, VL-102 also increased c-fos and CGRP expressing cells within the trigeminovascular complex. Importantly, ODQ completely inhibited acute and chronic hyperalgesia induced by nitroglycerin. ODQ also blocked hyperalgesia already established by chronic nitroglycerin, implicating this pathway in migraine chronicity. Conclusions These results indicate that nitroglycerin causes migraine-related pain through stimulation of the sGC pathway, and that super-activation of this receptor may be an important component for the maintenance of chronic migraine. This work opens the possibility for negative sGC modulators as novel migraine therapies.

Biochemical comparison of four commercially available human α1-proteinase inhibitors for treatment of α1-antitrypsin deficiency.

Intravenous therapy with purified plasma-derived alpha1-proteinase inhibitor (α1-PI) concentrates is the only specific treatment for α1-PI deficiency. For the therapy to be safe and efficacious, α1-PI concentrates should be highly pure and contain high amounts of functional protein. This study compared the four plasma-derived α1-PI products commercially available in Europe (Respreeza, Prolastin, Alfalastin, Trypsone) by biochemical methods with respect to function, purity, structure, and chemical modifications. Respreeza had the highest level of functional protein (48.8 mg/mL) and the highest specific activity (0.862 mg active α1-PI per mg total protein). By size exclusion chromatography, Respreeza was 97.4% pure, followed by Alfalastin 88.1%, Prolastin 76.9%, and Trypsone 70.8%. By reversed phase chromatography, Respreeza had an α1-PI purity of 97.7%, followed by Trypsone 88.0%, Prolastin 78.0%, and Alfalastin 69.5%. The main protein band by sodium dodecyl sulphate-polyacrylamide gel electrophoresis was found for all products at approximately 50 kDa. Additional protein bands were found for Prolastin, Alfalastin, and Trypsone. The α1-PI products differed in cysteine oxidation state and C-terminal lysine status. α1-PI products tested differ in purity, concentration, and chemical variation. Respreeza has the highest level of purity. The impact of the non-therapeutic proteins identified has not been evaluated.

Stuck with pancytopenia in dengue fever: Evoke for hemophagocytic syndrome.

The hemophagocytic syndrome is an atypical and rare manifestation of dengue fever (DF). We describe a 15-year-old girl developing DF associated hemophagocytic syndrome who responded with supportive treatment.

Adrenal hematoma and right hemothorax after echis carinatus bite: an unusual manifestation.

Common bleeding manifestations after viperine bite include bleeding from site of bite, bleeding gums, epistaxis, hemoptysis, hematuria, hematemesis, and intracranial bleed. Bleeding in the adrenal gland is a rare manifestation. We report here a patient of viperine bite who developed right adrenal hematoma and right hemothorax after 3 days of bite. To the best of our knowledge this is the first case report of adrenal hematoma and right hemothorax after Echis carinatus bite.

Phase I study of the pharmacokinetics and safety of rezafungin in subjects with moderate/severe hepatic impairment and matched control subjects.

INTRODUCTION: Rezafungin is a second-generation, once-weekly echinocandin antifungal approved for the treatment of invasive candidiasis, including candidemia. In phase II/III studies of rezafungin versus caspofungin, patients with severe hepatic impairment were excluded due to lack of caspofungin data in this population. This open-label, single-dose, phase I study evaluated the pharmacokinetics (primary objective) and safety of rezafungin in subjects with moderate or severe hepatic impairment versus matched, healthy subjects with normal hepatic function. METHODS: Eight subjects each with moderate (Child-Pugh B) or severe (Child-Pugh C) hepatic impairment were matched 1:1 with healthy subjects for age, sex, and body mass index. Each subject received a single 400-mg, intravenous, 1-h infusion of rezafungin. Plasma pharmacokinetic sampling was performed at various time points through 336 h postdose. Pharmacokinetic parameters were derived by non-compartmental analysis. Safety was assessed throughout. RESULTS: All 32 subjects received study treatment and were included in all analyses. Despite overlapping distributions of total plasma concentrations, based on geometric least-squares (LS) mean ratios, the area under the plasma concentration-time curve from time zero (prior to the start of infusion) to infinity (AUC0-∞) was 32% lower in subjects with moderate (LS mean ratio, 67.55; 90% confidence interval [CI]: 53.91, 84.65) and severe (LS mean ratio, 67.84; 90% CI: 57.49, 80.05) hepatic impairment versus matched healthy subjects. The maximum plasma concentration (Cmax) was 12% lower in moderate hepatic impairment and 28% lower in severe hepatic impairment groups. Linear regression showed no significant trend in the degree of hepatic impairment (based on Child-Pugh score) on AUC0-∞ or Cmax (p > 0.05). Treatment-emergent adverse events were reported in seven subjects (21.9%; three subjects in each of the hepatic impairment groups, and one healthy subject), none of which were severe, serious, or resulted in withdrawal. CONCLUSIONS: Rezafungin is well tolerated and can be administered to patients with moderate or severe hepatic impairment without the need for dose adjustment. The modest reduction in exposures in subjects with hepatic impairment is not clinically meaningful and is unlikely to impact efficacy.

Comparative activities of telavancin combined with nafcillin, imipenem, and gentamicin against Staphylococcus aureus.

Beta-lactams enhance the killing activity of vancomycin. Due to structural and mechanistic similarities between vancomycin and telavancin, we investigated the activity of telavancin combined with nafcillin and imipenem compared to the known synergistic combination of telavancin and gentamicin. Thirty strains of Staphylococcus aureus, 10 methicillin-susceptible S. aureus (MSSA), 10 methicillin-resistant S. aureus (MRSA), and 10 heterogeneously vancomycin-intermediate S. aureus (hVISA), were tested for synergy by time-kill methodology. Six strains (2 each of MSSA, MRSA, and hVISA) were further evaluated in an in vitro pharmacokinetic/pharmacodynamic (PK/PD) model with simulated regimens of 10 mg/kg of body weight of telavancin once daily alone and combined with 2 g nafcillin every 4 h, 500 mg imipenem every 6 h, or 5 mg/kg gentamicin once daily over 72 h. In the synergy test, 67% of strains displayed synergy with the combination of telavancin and gentamicin, 70% with telavancin and nafcillin, and 63% with telavancin and imipenem. In the PK/PD model, the activities of all three combinations against MRSA and hVISA were superior to all individual drugs alone (P ≤ 0.002) and were similar to each other (P ≥ 0.187). The activities of all three combinations against MSSA were generally similar to each other except for one strain where the combination of telavancin and imipenem was superior to all other regimens (P ≤ 0.011). The activity of the combination of telavancin and beta-lactam agents was similar to that of telavancin and gentamicin against S. aureus, including resistant strains. Because beta-lactam combinations are less likely to be nephrotoxic than telavancin plus gentamicin, these beta-lactam combinations may have clinical utility.

Evaluating the Safety of Maribavir for the Treatment of Cytomegalovirus.

Purpose of Review: Cytomegalovirus (CMV) infections are a common complication in solid organ (SOT) and hematopoietic stem cell transplant (HSCT) recipients, leading to increased morbidity and mortality. Currently available treatment options have reduced the burden of infection, but utilization of these agents can be limited by toxicities such as nephrotoxicity and/or myelosuppression as well as emergence of resistance. The expansion of our current armamentarium towards CMV infection is crucial. Here, we review an emerging therapy, maribavir, and the safety and efficacy of this potential new agent for the prophylaxis and treatment of CMV infections including resistant/refractory disease. Recent Findings: Maribavir is a novel agent with CMV activity approved by Federal Food and Drug Administration (FDA) in December 2021 for resistant/refractory disease. Compared to currently available treatment for CMV infection, maribavir has a unique mechanism of action, retains activity against most (val)ganciclovir resistant strains, provides a more predictable pharmacokinetic profile, and fewer severe toxicities. Maribavir has been studied in phase 2 and 3 studies with ongoing phase 3 studies. While maribavir failed to meet the primary endpoints in the initial phase 3 study for prophylaxis therapy in allogeneic-HSCT and liver transplant recipients, results from the phase 2 study when used for pre-emptive therapy after HSCT show similar efficacy to valganciclovir, and results from the phase 3 study examining resistant/refractory disease demonstrate superiority to investigator-initiated therapy of (val)ganciclovir, foscarnet, or cidofovir. Summary: Maribavir provides a new agent for the management of resistant/refractory CMV infection. Results of the recently published phase 3 study provide further insight into the role of this novel therapy.

Renal Crisis as the Initial Manifestation of Scleroderma.

We report the case of a young Hispanic woman who was originally admitted to the emergency department following hypertensive urgency and right-sided blurry vision. The patient did not carry a diagnosis of scleroderma at the time of the visit. However, upon further evaluation, the patient was found to have a scleroderma renal crisis. An angiotensin-converting enzyme (ACE) inhibitor was initiated promptly with subsequent normalization of the blood pressure and creatinine level. Scleroderma renal crisis is a rare, highly feared complication of scleroderma that if left untreated can be life-threatening. Therefore, it is important to identify this condition early and initiate therapy without delay.