Development of rabbit models of ventilator-associated bacterial pneumonia produced by carbapenem-resistant Pseudomonas aeruginosa.

Ventilator-associated bacterial pneumonia (VABP) is among the most intractable of carbapenem-resistant Gram-negative bacterial infections. New antimicrobial agents are critically needed for the treatment of VABP. However, current conventionally used animal model systems are inadequate to meet this challenge. We, therefore, developed rabbit models of VABP caused by carbapenem-resistant Pseudomonas aeruginosa. Persistently neutropenic New Zealand White rabbits were used throughout the study. The early-phase intubated model (0-24 h) received mechanical ventilation, while the late-phase intubated model (72-96 h) was ambulatory. The following outcome parameters were studied: survival, residual tissue bacterial burden (CFU/g), residual BAL bacterial burden (CFU/mL), lung weights, pulmonary lesion score, histology, O2 saturation, radiographic imaging, and histology. Each anesthetized rabbit received a predetermined endotracheal bacterial inoculum, and ventilators were set to FiO2 = 40% and PEEP = 8 mmHg. Within the first 12 h post-inoculation, mean bacterial burdens in lung tissue and BAL fluid, respectively, were established at approximately 107 CFU/g and 106 CFU/mL, persisted through 24 h in the early-phase model and increased in the late-phase model to approximately 108 CFU/g and 107 CFU/mL. Mean max SpO2 was ≥98 mmHg, and mean nadir SpO2 was ≥68 mmHg. Serial thoracic radiographs demonstrated progressive multilobar pneumonic infiltrates. Lung histology revealed progressive focal bronchopneumonia, coagulative necrosis, intra-alveolar hemorrhage, alveolar epithelial cell necrosis, and bacterial microcolonies. The new rabbit model of VABP produced by carbapenem-resistant Pseudomonas aeruginosa recapitulates the pathophysiological, microbiological, diagnostic imaging, and histological patterns of human disease by which to assess critically needed new antimicrobial agents against this lethal infection.

Combination of Systemic and Lock-Therapies with Micafungin Eradicate Catheter-Based Biofilms and Infections Caused by Candida albicans and Candida parapsilosis in Neutropenic Rabbit Models.

Vascular catheter-related infections, primarily caused by Candida albicans and Candida parapsilosis, pose significant challenges due to the formation of biofilms on catheters, leading to refractory disease and considerable morbidity. We studied the efficacy of micafungin in systemic and lock therapies to eliminate catheter-based biofilms and deep tissue infections in experimental central venous catheter (CVC)-related candidemia in neutropenic rabbits. Silastic CVCs in rabbits were inoculated with 1 × 103 CFU/mL of C. albicans or C. parapsilosis, establishing catheter-based biofilm, and subjected to various treatments. Neutropenic rabbits treated with a combination of lock therapy and systemic micafungin demonstrated the most significant reduction in fungal burden, from 5.0 × 104 to 1.8 × 102 CFU/mL of C. albicans and from 5.9 × 104 to 2.7 × 102 CFU/mL of C. parapsilosis (p ≤ 0.001), in the CVC after 24 h, with full clearance of blood cultures after 72 h from treatment initiation. The combination of lock and systemic micafungin therapy achieved eradication of C. albicans from all studied tissues (0.0 ± 0.0 log CFU/g) vs. untreated controls (liver 7.5 ± 0.22, spleen 8.3 ± 0.25, kidney 8.6 ± 0.07, cerebrum 6.3 ± 0.31, vena cava 6.6 ± 0.29, and CVC wash 2.3 ± 0.68 log CFU/g) (p ≤ 0.001). Rabbits treated with a combination of lock and systemic micafungin therapy demonstrated a ≥2 log reduction in C. parapsilosis in all treated tissues (p ≤ 0.05) except kidney. Serum (1→3)-ß-D-glucan levels demonstrated significant decreases in response to treatment. The study demonstrates that combining systemic and lock therapies with micafungin effectively eradicates catheter-based biofilms and infections caused by C. albicans or C. parapsilosis, particularly in persistently neutropenic conditions, offering promising implications for managing vascular catheter-related candidemia and providing clinical benefits in cases where catheter removal is not feasible.

Prospective observational pilot study of the T2Resistance panel in the T2Dx system for detection of resistance genes in bacterial bloodstream infections.

Early initiation of antimicrobial therapy targeting resistant bacterial pathogens causing sepsis and bloodstream infections (BSIs) is critical for a successful outcome. The T2Resistance Panel (T2R) detects the following resistance genes within organisms that commonly cause BSIs directly from patient blood samples: blaKPC, blaCTXM-14/15, blaNDM/bla/IMP/blaVIM, blaAmpC, blaOXA, vanA, vanB, and mecA/mecC. We conducted a prospective study in two major medical centers for the detection of circulating resistance genes by T2R in patients with BSIs. T2R reports were compared to antimicrobial susceptibility testing (AST), phenotypic identification, and standard molecular detection assays. Among 59 enrolled patients, 25 resistance genes were identified: blaKPC (n = 10), blaNDM/bla/IMP/blaVIM (n = 5), blaCTXM-14/15 (n = 4), blaAmpC (n = 2), and mecA/mecC (n = 4). Median time-to-positive-T2R in both hospitals was 4.4 hours [interquartile range (IQR): 3.65-4.97 hours] in comparison to that for positive blood cultures with final reporting of AST of 58.34 h (IQR: 45.51-111.2 hours; P < 0.0001). The sensitivity of T2R to detect the following genes in comparison to AST was 100% for blaCTXM-14/15, blaNDM/bla/IMP/blaVIM, blaAmpC, mecA/mecC and 87.5% for blaKPC. When monitored for the impact of significant antimicrobial changes, there were 32 events of discontinuation of unnecessary antibiotics and 17 events of escalation of antibiotics, including initiation of ceftazidime/avibactam in six patients in response to positive T2R results for blaKPC. In summary, T2R markers were highly sensitive for the detection of drug resistance genes in patients with bacterial BSIs, when compared with standard molecular resistance detection systems and phenotypic identification assays while significantly reducing by approximately 90% the time to detection of resistance compared to standard methodology and impacting clinical decisions for antimicrobial therapy. IMPORTANCE: This is the first reported study to our knowledge to identify key bacterial resistance genes directly from the bloodstream within 3 to 5 hours in patients with bloodstream infections and sepsis. The study further demonstrated a direct effect in modifying initial empirical antibacterial therapy in response to T2R signal to treat resistant bacteria causing bloodstream infections and sepsis.

FDA Public Workshop Summary-Addressing Challenges in Inhaled Antifungal Drug Development.

Allergic bronchopulmonary aspergillosis and invasive fungal diseases represent distinct infectious entities that cause significant morbidity and mortality. Currently, administered inhaled antifungal therapies are unapproved, have suboptimal efficacy, and are associated with considerable adverse reactions. The emergence of resistant pathogens is also a growing concern. Inhaled antifungal development programs are challenged by inadequate nonclinical infection models, highly heterogenous patient populations, low prevalence rates of fungal diseases, difficulties defining clinical trial enrollment criteria, and lack of robust clinical trial endpoints. On September 25, 2020, the US Food and Drug Administration (FDA) convened a workshop with experts in pulmonary medicine and infectious diseases from academia, industry, and other governmental agencies. Key discussion topics included regulatory incentives to facilitate development of inhaled antifungal drugs and combination inhalational devices, limitations of existing nonclinical models and clinical trial designs, patient perspectives, and industry insights.

Hyphae of Rhizopus arrhizus and Lichtheimia corymbifera Are More Virulent and Resistant to Antifungal Agents Than Sporangiospores In Vitro and in Galleria mellonella.

Mucorales species cause debilitating, life-threatening sinopulmonary diseases in immunocompromised patients and penetrating wounds in trauma victims. Common antifungal agents against mucormycosis have significant toxicity and are often ineffective. To evaluate treatments against mucormycosis, sporangiospores are typically used for in vitro assays and in pre-clinical animal models of pulmonary infections. However, in clinical cases of wound mucormycosis caused by traumatic inoculation, hyphal elements found in soil are likely the form of the inoculated organism. In this study, Galleria mellonella larvae were infected with either sporangiospores or hyphae of Rhizopus arrhizus and Lichtheimia corymbifera. Hyphal infections resulted in greater and more rapid larval lethality than sporangiospores, with an approximate 10-16-fold decrease in LD50 of hyphae for R. arrhizus (p = 0.03) and L. corymbifera (p = 0.001). Liposomal amphotericin B, 10 mg/kg, was ineffective against hyphal infection, while the same dosage was effective against infections produced by sporangiospores. Furthermore, in vitro, antifungal susceptibility studies show that minimum inhibitory concentrations of several antifungal agents against hyphae were higher when compared to those of sporangiospores. These findings support using hyphal elements of Mucorales species for virulence testing and antifungal drug screening in vitro and in G. mellonella for studies of wound mucormycosis.

A conceptual framework for nomenclatural stability and validity of medically important fungi: a proposed global consensus guideline for fungal name changes supported by ABP, ASM, CLSI, ECMM, ESCMID-EFISG, EUCAST-AFST, FDLC, IDSA, ISHAM, MMSA, and MSGERC.

The rapid pace of name changes of medically important fungi is creating challenges for clinical laboratories and clinicians involved in patient care. We describe two sources of name change which have different drivers, at the species versus the genus level. Some suggestions are made here to reduce the number of name changes. We urge taxonomists to provide diagnostic markers of taxonomic novelties. Given the instability of phylogenetic trees due to variable taxon sampling, we advocate to maintain genera at the largest possible size. Reporting of identified species in complexes or series should where possible comprise both the name of the overarching species and that of the molecular sibling, often cryptic species. Because the use of different names for the same species will be unavoidable for many years to come, an open access online database of the names of all medically important fungi, with proper nomenclatural designation and synonymy, is essential. We further recommend that while taxonomic discovery continues, the adaptation of new name changes by clinical laboratories and clinicians be reviewed routinely by a standing committee for validation and stability over time, with reference to an open access database, wherein reasons for changes are listed in a transparent way.

Real-world Use of Mold-Active Triazole Prophylaxis in the Prevention of Invasive Fungal Diseases: Results From a Subgroup Analysis of a Multicenter National Registry.

Background: Antifungal prophylaxis can prevent invasive fungal diseases (IFDs) in high-risk, immunocompromised patients. This study assessed the real-world use of mold-active triazoles (MATs) for the prevention of IFDs. Methods: This subgroup analysis of a multicenter, observational, prospective registry in the United States from March 2017 to April 2020 included patients who received MATs for prophylaxis (isavuconazole, posaconazole, and voriconazole) at study index/enrollment. The primary objective was to describe patient characteristics and patterns of MAT use. Exploratory assessments included the frequency of breakthrough IFDs and MAT-related adverse drug reactions (ADRs). Results: A total of 1177 patients (256 isavuconazole, 397 posaconazole, 272 voriconazole, and 252 multiple/sequenced MATs at/after index/enrollment) were included in the prophylaxis subgroup analysis. Patient characteristics were similar across MAT groups, but risk factors varied. Hematological malignancy predominated (76.5%) across all groups. Breakthrough IFDs occurred in 7.1% (73/1030) of patients with an investigator's assessment (5.0% [11/221] isavuconazole; 5.3% [20/374] posaconazole; 4.0% [9/226] voriconazole; and 15.8% [33/209] multiple/sequenced MATs). Aspergillus (29.5% [18/61]) and Candida (36.1% [22/61]) species were the most common breakthrough pathogens recovered. ADRs were reported in 14.1% of patients, and discontinuation of MATs due to ADRs was reported in 11.1% of patients (2.0% [5/245] isavuconazole; 8.2% [30/368] posaconazole; and 10.1% [27/267] voriconazole). Conclusions: Breakthrough IFDs were uncommon in patients who received MATs for prophylaxis. Candida and Aspergillus species were the most commonly reported breakthrough pathogens. The discontinuation of MATs due to ADRs was infrequent. These findings support prophylactic strategies with isavuconazole, posaconazole, and voriconazole in high-risk patients.

Food and Drug Administration Public Workshop Summary-Development Considerations of Antifungal Drugs to Address Unmet Medical Need.

Pressing challenges in the treatment of invasive fungal infections (IFIs) include emerging and rare pathogens, resistant/refractory infections, and antifungal armamentarium limited by toxicity, drug-drug interactions, and lack of oral formulations. Development of new antifungal drugs is hampered by the limitations of the available diagnostics, clinical trial endpoints, prolonged trial duration, difficulties in patient recruitment, including subpopulations (eg, pediatrics), and heterogeneity of the IFIs. On 4 August 2020, the US Food and Drug Administration convened a workshop that included IFI experts from academia, industry, and other government agencies to discuss the IFI landscape, unmet need, and potential strategies to facilitate the development of antifungal drugs for treatment and prophylaxis. This article summarizes the key topics presented and discussed during the workshop, such as incentives and research support for drug developers, nonclinical development, clinical trial design challenges, lessons learned from industry, and potential collaborations to facilitate antifungal drug development.

Non-Aspergillus Hyaline Molds: A Host-Based Perspective of Emerging Pathogenic Fungi Causing Sinopulmonary Diseases.

The incidence of invasive sino-pulmonary diseases due to non-Aspergillus hyaline molds is increasing due to an enlarging and evolving population of immunosuppressed hosts as well as improvements in the capabilities of molecular-based diagnostics. Herein, we review the following opportunistic pathogens known to cause sinopulmonary disease, the most common manifestation of hyalohyphomycosis: Fusarium spp., Scedosporium spp., Lomentospora prolificans, Scopulariopsis spp., Trichoderma spp., Acremonium spp., Paecilomyces variotii, Purpureocillium lilacinum, Rasamsonia argillacea species complex, Arthrographis kalrae, and Penicillium species. To facilitate an understanding of the epidemiology and clinical features of sino-pulmonary hyalohyphomycoses in the context of host immune impairment, we utilized a host-based approach encompassing the following underlying conditions: neutropenia, hematologic malignancy, hematopoietic and solid organ transplantation, chronic granulomatous disease, acquired immunodeficiency syndrome, cystic fibrosis, and healthy individuals who sustain burns, trauma, or iatrogenic exposures. We further summarize the pre-clinical and clinical data informing antifungal management for each pathogen and consider the role of adjunctive surgery and/or immunomodulatory treatments to optimize patient outcome.

Meeting the Challenges of Sepsis in Severe Coronavirus Disease 2019: A Call to Arms.

Sepsis is a life-threatening organ dysfunction that is caused by a dysregulated host response to infection. Sepsis may be caused by bacterial, fungal, or viral pathogens. The clinical manifestations exhibited by patients with severe coronavirus disease 2019 (COVID-19)-related sepsis overlap with those exhibited by patients with sepsis from secondary bacterial or fungal infections and can include an altered mental status, dyspnea, reduced urine output, tachycardia, and hypotension. Critically ill patients hospitalized with severe acute respiratory syndrome coronavirus 2 infections have increased risk for secondary bacterial and fungal infections. The same risk factors that may predispose to sepsis and poor outcome from bloodstream infections (BSIs) converge in patients with severe COVID-19. Current diagnostic standards for distinguishing between (1) patients who are critically ill, septic, and have COVID-19 and (2) patients with sepsis from other causes leave healthcare providers with 2 suboptimal choices. The first choice is to empirically administer broad-spectrum, antimicrobial therapy for what may or may not be sepsis. Such treatment may not only be ineffective and inappropriate, but it also has the potential to cause harm. The development of better methods to identify and characterize antimicrobial susceptibility will guide more accurate therapeutic interventions and reduce the evolution of new antibiotic-resistant strains. The ideal diagnostic test should (1) be rapid and reliable, (2) have a lower limit of detection than blood culture, and (3) be able to detect a specific organism and drug sensitivity directly from a clinical specimen. Rapid direct detection of antimicrobial-resistant pathogens would allow targeted therapy and result in improved outcomes in patients with severe COVID-19 and sepsis.

Development of a Corticosteroid-Immunosuppressed Mouse Model to Study the Pathogenesis and Therapy of Influenza-Associated Pulmonary Aspergillosis.

Influenza-associated pulmonary aspergillosis (IAPA) is a feared complication in patients with influenza tracheobronchitis, especially those receiving corticosteroids. Herein, we established a novel IAPA mouse model with low-inoculum Aspergillus infection and compared outcomes in mice with and without cortisone acetate (CA) immunosuppression. CA was an independent predictor of increased morbidity/mortality in mice with IAPA. Early antifungal treatment with liposomal amphotericin B was pivotal to improve IAPA outcomes in CA-immunosuppressed mice, even after prior antiviral therapy with oseltamivir. In summary, our model recapitulates key clinical features of IAPA and provides a robust preclinical platform to study the pathogenesis and treatment of IAPA.

Osteoarticular Mycoses.

Osteoarticular mycoses are chronic debilitating infections that require extended courses of antifungal therapy and may warrant expert surgical intervention. As there has been no comprehensive review of these diseases, the International Consortium for Osteoarticular Mycoses prepared a definitive treatise for this important class of infections. Among the etiologies of osteoarticular mycoses are Candida spp., Aspergillus spp., Mucorales, dematiaceous fungi, non-Aspergillus hyaline molds, and endemic mycoses, including those caused by Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides species. This review analyzes the history, epidemiology, pathogenesis, clinical manifestations, diagnostic approaches, inflammatory biomarkers, diagnostic imaging modalities, treatments, and outcomes of osteomyelitis and septic arthritis caused by these organisms. Candida osteomyelitis and Candida arthritis are associated with greater events of hematogenous dissemination than those of most other osteoarticular mycoses. Traumatic inoculation is more commonly associated with osteoarticular mycoses caused by Aspergillus and non-Aspergillus molds. Synovial fluid cultures are highly sensitive in the detection of Candida and Aspergillus arthritis. Relapsed infection, particularly in Candida arthritis, may develop in relation to an inadequate duration of therapy. Overall mortality reflects survival from disseminated infection and underlying host factors.

Therapeutic Bacteriophages for Gram-Negative Bacterial Infections in Animals and Humans.

Drug-resistant Gram-negative bacterial pathogens are an increasingly serious health threat causing worldwide nosocomial infections with high morbidity and mortality. Of these, the most prevalent and severe are Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii, and Salmonella typhimurium. The extended use of antibiotics has led to the emergence of multidrug resistance in these bacteria. Drug-inactivating enzymes produced by these bacteria, as well as other resistance mechanisms, render drugs ineffective and make treatment of such infections more difficult and complicated. This makes the development of novel antimicrobial agents an urgent necessity. Bacteriophages, which are bacteria-killing viruses first discovered in 1915, have been used as therapeutic antimicrobials in the past, but their use was abandoned due to the widespread availability of antibiotics in the 20th century. The emergence, however, of drug-resistant pathogens has re-affirmed the need for bacteriophages as therapeutic strategies. This review describes the use of bacteriophages as novel agents to combat this rapidly emerging public health crisis by comprehensively enumerating and discussing the innovative use of bacteriophages in both animal models and in patients infected by Gram-negative bacteria.

Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor (rhu GM-CSF) as Adjuvant Therapy for Invasive Fungal Diseases.

Background: Sargramostim (yeast-derived, glycosylated recombinant human granulocyte-macrophage colony-stimulating factor [rhu GM-CSF]) augments innate and adaptive immune responses and accelerates hematopoietic recovery of chemotherapy-induced neutropenia. However, considerably less is known about its efficacy as adjunctive immunotherapy against invasive fungal diseases (IFDs). Methods: The clinical courses of 15 patients with pediatric malignancies and IFDs treated adjunctively with sargramostim at a single institution were analyzed in a retrospective cohort review. Further, a systematic review of published reports of rhu GM-CSF for IFDs was also conducted. Results: Among 65 cases, 15 were newly described pediatric patients and 50 were previously published cases of IFDs treated with rhu GM-CSF. Among the newly reported pediatric patients, IFDs were caused by Candida spp., Trichosporon sp., and molds (Aspergillus spp., Rhizopus sp., Lichtheimia sp., and Scedosporium sp). Twelve (80%) were neutropenic at baseline, and 12 (80%) were refractory to antifungal therapy. Among 12 evaluable patients, the overall response rate was 92% (8 [67%] complete responses, 3 [25%] partial responses, and 1 [8%] stable). Treatment is ongoing in the remaining 3 patients. Among 50 published cases (15 Candida spp., 13 Mucorales, 11 Aspergillus spp., 11 other organisms), 20 (40%) had baseline neutropenia and 36 (72%) were refractory to standard therapy before rhu GM-CSF administration. Consistent with responses in the newly reported patients, the overall response rate in the literature review was 82% (40 [80%] complete responses, 1 [2%] partial response, and 9 [18%] no response). Conclusions: Sargramostim may be a potential adjunctive immunomodulator for selected patients with hematological malignancies and refractory IFDs.

Ibrexafungerp, a Novel Triterpenoid Antifungal in Development for the Treatment of Mold Infections.

Molds are ubiquitous in the environment, and immunocompromised patients are at substantial risk of morbidity and mortality due to their underlying disease and the resistance of pathogenic molds to currently recommended antifungal therapies. This combination of weakened-host defense, with limited antifungal treatment options, and the opportunism of environmental molds renders patients at risk and especially vulnerable to invasive mold infections such as Aspergillus and members of the Order Mucorales. Currently, available antifungal drugs such as azoles and echinocandins, as well as combinations of the same, offer some degree of efficacy in the prevention and treatment of invasive mold infections, but their use is often limited by drug resistance mechanisms, toxicity, drug-drug interactions, and the relative paucity of oral treatment options. Clearly, there is a need for agents that are of a new class that provides adequate tissue penetration, can be administered orally, and have broad-spectrum efficacy against fungal infections, including those caused by invasive mold organisms. Ibrexafungerp, an orally bioavailable glucan synthase inhibitor, is the first in a new class of triterpenoid antifungals and shares a similar target to the well-established echinocandins. Ibrexafungerp has a very favorable pharmacokinetic profile for the treatment of fungal infections with excellent tissue penetration in organs targeted by molds, such as the lungs, liver, and skin. Ibrexafungerp has demonstrated in vitro activity against Aspergillus spp. as well as efficacy in animal models of invasive aspergillosis and mucormycosis. Furthermore, ibrexafungerp is approved for use in the USA for the treatment of women with vulvovaginal candidiasis. Ibrexafungerp is currently being evaluated in clinical trials as monotherapy or in combination with other antifungals for treating invasive fungal infections caused by yeasts and molds. Thus, ibrexafungerp offers promise as a new addition to the clinician's armamentarium against these difficult-to-treat infections.

Are Nutraceuticals Effective in COVID-19 and Post-COVID Prevention and Treatment?

The beginning of the end or the end of the beginning? After two years mastered by coronavirus disease 19 (COVID-19) pandemic, we are now witnessing a turnaround. The reduction of severe cases and deaths from COVID-19 led to increasing importance of a new disease called post-COVID syndrome. The term post-COVID is used to indicate permanency of symptoms in patients who have recovered from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Immune, antiviral, antimicrobial therapies, as well as ozone therapy have been used to treat COVID-19 disease. Vaccines have then become available and administered worldwide to prevent the insurgence of the disease. However, the pandemic is not over yet at all given the emergence of new omicron variants. New therapeutic strategies are urgently needed. In this view, great interest was found in nutraceutical products, including vitamins (C, D, and E), minerals (zinc), melatonin, probiotics, flavonoids (quercetin), and curcumin. This review summarizes the role of nutraceuticals in the prevention and/or treatment of COVID-19 disease and post-COVID syndrome.