Amphotericin B lipid complex for the treatment of invasive fungal infections

COVID associated pulmonary mucormycosis: Outcomes of surgical therapy

OBJECTIVES

This study aims at reporting the surgical outcomes of COVID associated pulmonary mucormycosis with special emphasis on surgical mortality.

METHODS

This prospective observational study was conducted in a dedicated thoracic surgical unit in Gurugram, India over 18 months. An analysis of demography, peri-operative variables were carried out. Various parameters were analysed to assess the factors affecting mortality.

RESULTS

Total of 44 patients with diagnosis of CAPM were managed during the study period. All were started on anti-fungal therapy. However, 33 patients (75%) were operated whereas rest 11 (25%) were not considered suitable for surgery. In the surgical cohort (n  =  33), there were 20 males (60.6%) and 13 females (39.4%), with a mean age of 54.8 years (range, 33-72 years). The mean duration of the symptoms was 1.1 weeks. Non-anatomical wedge resection of lobe(s) was performed in 5 patients (15.1%), lobectomy/bi-lobectomy was required in 26 patients (78.9%) and left pneumonectomy in 2 patients (6%). There were 5 peri-operative deaths (15.1%), all due to fungal sepsis. ECOG scale > 2 (P  ≤  0.001), higher Charlson Comorbidity Index score > 2 (P  =  0.04) and pneumonectomy (P  =  0.02) were the predictors of mortality. On comparison with NCPM, there was no difference in the incidence of post-operative complications (P  =  0.50) and the post-operative mortality (P  =  0.69).

CONCLUSION

Aggressive surgical resection with clear margins should be offered in CAPM, whenever feasible. Surgery for CAPM was not associated with higher post-operative complications including mortality compared to Non-COVID Pulmonary Mucormycosis.

Versatile Encapsulation and Synthesis of Potent Liposomes by Thermal Equilibration

The wide-scale use of liposomal delivery systems is challenged by difficulties in obtaining potent liposomal suspensions. Passive and active loading strategies have been proposed to formulate drug encapsulated liposomes but are limited by low efficiencies (passive) or high drug specificities (active). Here, we present an efficient and universal loading strategy for synthesizing therapeutic liposomes. Integrating a thermal equilibration technique with our unique liposome synthesis approach, co-loaded targeting nanovesicles can be engineered in a scalable manner with potencies 200-fold higher than typical passive encapsulation techniques. We demonstrate this capability through simultaneous co-loading of hydrophilic and hydrophobic small molecules and targeted delivery of liposomal Doxorubicin to metastatic breast cancer cell line MDA-MB-231. Molecular dynamic simulations are used to explain interactions between Doxorubicin and liposome membrane during thermal equilibration. By addressing the existing challenges, we have developed an unparalleled approach that will facilitate the formulation of novel theranostic and pharmaceutical strategies.

Outcomes of early anti-fungal therapy with aggressive surgical resection in pulmonary mucormycosis

Objectives

The standard management protocols are lacking in the management of pulmonary mucormycosis (PM). The present study aims at reporting our clinical experience and proposing an algorithm for the management of PM.

Materials and Methods

This is a retrospective analysis of a prospectively maintained database at a dedicated thoracic surgical unit in New Delhi, India, over 7 years. An analysis of demographic characteristics and perioperative variables including complications was carried out. Various parameters were analyzed to assess the factors affecting mortality after surgical intervention.

Results

Out of total 19 patients, 15 were males (78.9%) and 4 females (21.1%), with a mean age of 43.8 years (range, 19-72 years). Chronic kidney disease (status postrenal transplant on immunosuppressant therapy) was the most common predisposing factor in 11 patients (57.8%). All patients were initially started on antifungal therapy, and after 7-8 days, the response was assessed by computed tomography scan of the chest, and based on that, 15 patients (78.9%) were operated (surgical group) and the rest 4 (21.1%) were not (nonsurgical group). In the surgical group, lobectomy was required in 12 (80%) and pneumonectomy in 3 patients (20%). Postoperative complications occurred in 5 patients (33.3%). There were 3 perioperative deaths (within 90 days of surgery) (20%). Poor Eastern Cooperative Oncology Group performance status (>2) and longer duration of symptoms (>2 weeks) were independent predictors of mortality after surgery. The survivors in the surgical group are doing well. However, all four patients in the nonsurgical group died due to disease progression.

Conclusion

After few days of initiation of antifungal therapy, aggressive surgical resection must be performed (wherever feasible) to improve survival outcome in patients with PM.

Characteristics of pulmonary mucormycosis and the experiences of surgical resection

Background

Pulmonary mucormycosis (PM) is a relatively rare but fatal infection. However, detailed surgery data have been lacking. We summarized the characteristics of this rare disease and clarified the experiences of surgical resection

Methods

We conducted a single-center retrospective study of seven patients with PM who underwent surgical resection at China-Japan Friendship Hospital from May 2011 to May 2018.

Results

Patient ages ranged from 18 to 70 years, with a median age of 47 years. Manual workers (85.7%) were the most common occupation and their educational level was also below high school. Diabetes was the most common underlying condition. The most common radiographic finding was lobar consolidation. Three patients directly underwent open thoracotomy, one patient underwent video-assisted thoracic surgery (VATS) and three patients converted from VATS to thoracotomy. The median operation time was 240 min [interquartile range (IQR), 150–390 min], the median intraoperative blood loss was 500 mL (IQR, 100–1,200 mL) and the median intraoperative blood transfusion was 600 mL (IQR, 0–1,600 mL). In-hospital, 90-day, 1-year and 5-year mortality were 14.3%, 14.3%, 28.8% and 42.9%, respectively.

Conclusions

PM is a rare but fatal infection. Due to chest adhesion and vascular invasion, the proportion of massive bleeding and long operation time has increased sharply.

Antifungal susceptibility profile of Aspergillus fumigatus isolates from avian lungs

ABSTRACT: Susceptibility testing is essential to inform the correct management of Aspergillus infections. In this study we present antifungal susceptibility profile of A. fumigatus isolates recovered from lungs of birds with and without aspergillosis. Fifty three isolates were tested for their antifungal susceptibility to voriconazole (VRC), itraconazole (ITZ), amphotericin (AMB) and caspofungin (CSP) using the M38-A2 broth microdilution reference method. Five isolates were resistant to more than one antifungal drug (CSP + AMB, VRC + ITZ and AMB + ITZ). Fifteen (28%) isolates with susceptible increased exposure (I) to ITZ were sensible to VRC. Resistance to AMB (>2μg/mL) was observed in only four isolates. Eleven (21%) A. fumigatus present resistance to ITZ (13%) and VRC (8%). Fungal isolation from respiratory samples has been regarded as being of limited usefulness in the ante mortem diagnosis of aspergillosis in birds. However, the results suggest that the detection and antifungal susceptibility profile may be helpful for monitoring of therapy for avian species and where antifungal resistance might be emerging and what conditions are associated to the event.

New inhibitors of chorismate synthase present antifungal activity against Paracoccidioides brasiliensis

Aim: A structural model of chorismate synthase (CS) from the pathogenic fungus Candida albicans was used for virtual screening simulations. Methods: Docking, molecular dynamics, cell growth inhibition and protein binding assays were used for search and validation. Results: Two molecules termed CS8 and CaCS02 were identified. Further studies of the minimal inhibitory concentration demonstrated fungicidal activity against Paracoccidioides brasiliensis with a minimal inhibitory concentration and minimal fungicidal concentration of 512 and 32 μg·ml-1 for CS8 and CaCS02, respectively. In addition, CaCS02 showed a strong synergistic effect in combination with amphotericin B without cytotoxic effects. In vitro studies using recombinant CS from P. brasiliensis showed IC50 of 29 μM for CaCS02 supporting our interpretation that inhibition of CS causes the observed fungicidal activity.

Antifungal activity of two oxadiazole compounds for the paracoccidioidomycosis treatment

Paracoccidioidomycosis (PCM) is a neglected disease present in Latin America with difficulty in treatment and occurrence of serious sequelae. Thus, the development of alternative therapies is imperative. In the current work, two oxadiazole compounds (LMM5 and LMM11) presented fungicidal activity against Paracoccidioides spp. The minimum inhibitory and fungicidal concentration values ranged from 1 to 32 μg/mL, and a synergic effect was observed for both compounds when combined with Amphotericin B. LMM5 and LMM11 were able to reduce CFU counts (≥2 log10) on the 5th and 7th days of time-kill curve, respectively. The fungicide effect was confirmed by fluorescence microscopy (FUN-1/FUN-2). The hippocratic screening and biochemical analysis were performed in Balb/c male mice that received a high dose of each compound, and the compounds showed no in vivo toxicity. The treatment of experimental PCM with the new oxadiazoles led to significant reduction in CFU (≥1 log10). Histopathological analysis of the groups treated exhibited control of inflammation, as well as preserved lung areas. These findings suggest that LMM5 and LMM11 are promising hits structures, opening the door for implementing new PCM therapies.

Tissue penetration of antifungal agents

Understanding the tissue penetration of systemically administered antifungal agents is critical for a proper appreciation of their antifungal efficacy in animals and humans. Both the time course of an antifungal drug and its absolute concentrations within tissues may differ significantly from those observed in the bloodstream. In addition, tissue concentrations must also be interpreted within the context of the pathogenesis of the various invasive fungal infections, which differ significantly. There are major technical obstacles to the estimation of concentrations of antifungal agents in various tissue subcompartments, yet these agents, even those within the same class, may exhibit markedly different tissue distributions. This review explores these issues and provides a summary of tissue concentrations of 11 currently licensed systemic antifungal agents. It also explores the therapeutic implications of their distribution at various sites of infection.

Comparative pharmacodynamics of amphotericin B lipid complex and liposomal amphotericin B in a murine model of pulmonary mucormycosis

We compared the kinetics of amphotericin B (AMB) lung accumulation and fungal clearance by liposomal amphotericin B (L-AMB) and amphotericin B lipid complex (ABLC) in a neutropenic murine model of invasive pulmonary mucormycosis (IPM). Immunosuppressed BALB/c mice were inoculated with 1 x 10(6) Rhizopus oryzae spores and administered L-AMB or ABLC at daily intravenous doses of 1, 5, or 10 mg/kg of body weight for 5 days starting 12 h after infection. At a dose of 10 mg/kg/day, both L-AMB and ABLC were effective at reducing the R. oryzae lung fungal burden and achieved lung tissue concentrations exceeding the isolate mean fungicidal concentration (MFC) of 8 microg/ml by 72 h. When ABLC was dosed at 5 mg/kg/day, the ABLC-treated animals had significantly higher AMB lung concentrations than the L-AMB treated animals at 24 h (6.64 and 1.44 microg/g, respectively; P = 0.013) and 72 h (7.49 and 1.03 microg/g, respectively; P = 0.005), and these higher concentrations were associated with improved fungal clearance, as determined by quantitative real-time PCR (mean conidial equivalent of R. oryzae DNA per lung, 4.44 +/- 0.44 and 6.57 +/- 0.74 log(10), respectively; P < 0.001). Analysis of the AMB tissue concentration-response relationships revealed that the suppression of R. oryzae growth in the lung required tissue concentrations that approached the MFC for the infecting isolate (50% effective concentration, 8.19 microg/g [95% confidence interval, 2.81 to 18.1 microg/g]). The rates of survival were similar in the animals treated with L-AMB and ABLC at 10 mg/kg/day. These data suggest that higher initial doses may be required during L-AMB treatment than during ABLC treatment of experimental IPM.

Amphotericin B Formulations and Drug Targeting

Amphotericin B is a low-soluble polyene antibiotic which is able to self-aggregate. The aggregation state can modify its activity and pharmacokinetical characteristics. In spite of its high toxicity it is still widely employed for the treatment of systemic fungal infections and parasitic disease and different formulations are marketed. Some of these formulations, such as liposomal formulations, can be considered as classical examples of drug targeting. The pharmacokinetics, toxicity and activity are clearly dependent on the type of amphotericin B formulation. New drug delivery systems such as liposomes, nanospheres and microspheres can result in higher concentrations of AMB in the liver and spleen, but lower concentrations in kidney and lungs, so decreasing its toxicity. Moreover, the administration of these drug delivery systems can enhance the drug accessibility to organs and tissues (e.g., bone marrow) otherwise inaccessible to the free drug. During the last few years, new AMB formulations (AmBisome, Abelcet, and Amphotec) with an improved efficacy/toxicity ratio have been marketed. This review compares the different formulations of amphotericin B in terms of pharmacokinetics, toxicity and activity and discusses the possible drug targeting effect of some of these new formulations.

Management of Candida infections in the adult intensive care unit

The epidemiology of Candida infection in intensive care units (ICUs) and the management strategies for such infections in non-neutropenic intensive care patients are discussed in this review. Candida species are one of the leading causes of nosocomial bloodstream infections and a significant cause of morbidity in patients admitted to the ICU. Prophylactic, pre-emptive and empiric treatment strategies for Candida infections have been explored in ICU patients. Routine prophylaxis should not be administered to the whole population of ICU patients, because the concerns about the selection of azole-resistant Candida strains or the induction of resistance are justified. Treatment of fungal infections is now possible with newer antifungal agents, including newer azoles (e.g., voriconazole, posaconazole) and echinocandins (e.g., micafungin, anidulafungin). However, there is a critical need for improvement in diagnosis of invasive Candida infection in order to provide clinicians the opportunity to intervene earlier in the diseases course.

Outcomes of invasive zygomycosis infections in renal transplant recipients

Zygomycosis is an infrequent and difficult-to-treat fungal infection that is found in patients with underlying immunocompromised states. The advent of the lipid amphotericin B products has allowed for treatment with higher doses of therapy and less systemic toxicity. We reviewed the outcomes of 6 renal transplant recipients diagnosed with biopsy-proven invasive zygomycosis who received amphotericin B lipid complex (ABLC) in doses greater than 5 mg/kg between 2000 and 2004. All 6 patients had baseline diabetes mellitus, were receiving immunosuppressive agents, and subsequently underwent concomitant surgery. Three of the 6 patients that survived had undergone significant surgical debridement, reduction of their immunosuppression to minimal prednisone, and received prolonged course of ABLC at 10 mg/kg/day. All survivors lost graft function during the course of their therapy. The 3 patients who died all had delays in diagnosis of their disease and subsequent surgical and appropriate medical therapy. Therefore, in renal transplant recipients the early diagnosis of invasive zygomycosis is imperative along with early therapy with surgical debridement, reduced immunosuppression, and the use of high doses of ABLC.

Comparative analysis of amphotericin B lipid complex and liposomal amphotericin B kinetics of lung accumulation and fungal clearance in a murine model of acute invasive pulmonary aspergillosis

The reformulation of amphotericin B (AMB) into a lipid complex (AMB lipid complex [ABLC]) or liposomal carrier (liposomal AMB [L-AMB]) changes the rate and extent of drug distribution to the lung. The importance of pharmacokinetic differences among the various lipid AMB formulations in the treatment of invasive pulmonary aspergillosis (IPA) remains unknown. We compared the kinetics of AMB lung accumulation and fungal clearance of ABLC- and L-AMB-treated mice with acute IPA. BALB/c mice were immunosuppressed with cyclophosphamide and cortisone before intranasal inoculation with 1.5x10(6) Aspergillus fumigatus 293 conidia. ABLC or L-AMB was administered in daily intravenous doses (1, 5, or 10 mg/kg of body weight), starting 12 h after infection and continuing until day 5. At predetermined times (0, 24, 72, and 120 h), mice were euthanized, and lungs were harvested for determinations of lung fungal burdens (quantitative PCR) and total AMB lung tissue concentrations. Both ABLC and L-AMB were effective at reducing lung fungal burdens at doses of >or=5 mg/kg/day. Clearance of A. fumigatus during the first 24 h was associated with AMB tissue concentrations of >4 microg/g. At 5 mg/kg/day, ABLC produced a more rapid fungal clearance than did L-AMB, but at the end of therapy, fungal burden reductions were similar for both formulations and were not improved with higher dosages. These data suggest that ABLC delivers active AMB to the lung more rapidly than does L-AMB, resulting in faster Aspergillus clearance in an experimental model of IPA. However, pharmacodynamic differences between the two formulations were less apparent when mice were dosed at 10 mg/kg/day.

Pulmonary fungal infections

PURPOSE OF REVIEW

Invasive fungal infections of the lung have historically been associated with an extremely high mortality. This review aims to disseminate the most recent advances in the diagnosis and management of fungal infections of the lung.

RECENT FINDINGS

The number and diversity of immunosuppressed populations are growing rapidly. Transplant immunosuppression is becoming more aggressive early in the posttransplant period, potentially increasing the risk of invasive fungal infections. The galactomannan antigen test and the beta-D-glucan test have emerged as methods of serially monitoring at-risk patients for invasive aspergillosis. Their utility has been established in some neutropenic populations but not in solid organ transplant recipients. In-vitro studies, animal studies, and retrospective human studies support the use of combination antifungal therapy for invasive aspergillosis. Unfortunately no randomized clinical trials exist.

SUMMARY

Invasive pulmonary aspergillosis will continue to be a major problem in immunocompromised patients in the future. Immense advances in the last 2-3 years are sure to improve outcome. Well-designed multicenter evaluations are still necessary, however, to optimize management as management options widen.

Drug dosing in chronic kidney disease

Patients with chronic kidney disease (CKD) are at high risk for adverse drug reactions and drug-drug interactions. Drug dosing in these patients often proves to be a difficult task. Renal dysfunction-induced changes in human pathophysiology regularly results may alter medication pharmacodynamics and handling. Several pharmacokinetic parameters are adversely affected by CKD, secondary to a reduced oral absorption and glomerular filtration; altered tubular secretion; and reabsorption and changes in intestinal, hepatic, and renal metabolism. In general, drug dosing can be accomplished by multiple methods; however, the most common recommendations are often to reduce the dose or expand the dosing interval, or use both methods simultaneously. Some medications need to be avoided all together in CKD either because of lack of efficacy or increased risk of toxicity. Nevertheless, specific recommendations are available for dosing of certain medications and are an important resource, because most are based on clinical or pharmacokinetic trials.

Invasive aspergillosis in organ transplant recipients: new issues in epidemiologic characteristics, diagnosis, and management

Changing transplantation practices, novel immunosuppressive protocols, and evolving recipient characteristics have led to notable changes in the epidemiology of invasive aspergillosis in transplant recipients. The frequency of disseminated infection and of central nervous system involvement has declined significantly in organ transplant recipients in the recent years. Amongst variables that may have contributed to these trends is an overall lesser severity of illness of transplant recipients in the current era. Calcineurin-inhibitor immunosuppressive agents may also have had a role in altering the disease course and the risk of dissemination. A new paradigm in the management of post-transplant immunosuppression is the use of calcineurin-inhibitor and corticosteroid sparing regimens by pretreatment of the recipient with T-cell depleting agents (Campath 1-H or thymoglobulin) and utilization of minimal post-transplant immunosuppression. The impact of these potent lymphoablative regimens on opportunistic mycoses in organ transplant recipients remains to be fully discerned. Although still unacceptably high, the mortality rate in organ transplant recipients with invasive aspergillosis in the current era appears to have declined. A focus of a great interest and controversy is the use of combination therapy for invasive aspergillosis in transplant recipients.