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Biomedical subjects

John R Perfect

Publications and source records attributed to John R Perfect.

At least 55 records · Page 3Linked to original sources
PubMed2004

Value of an inhalational model of invasive aspergillosis.

Animal models of invasive aspergillosis have been used for virulence studies and antifungal efficacy evaluations but results have been inconsistent. In an attempt to reproduce human infection, many Aspergillus animal models have utilized a 'pulmonary route' for delivery of conidia, largely through intranasal instillation. However, several radiolabeled particle studies have shown that aerosol delivery is preferable to intranasal instillation to create a more homogenous delivery to the lungs. We hypothesized that an inhalational model would be more robust for studies of invasive aspergillosis pathogenesis and antifungal therapy. We developed an inhalational model of Aspergillus fumigatus infection using a Hinners inhalation chamber and demonstrated by quantitative polymerase chain reaction that this new inhalational model creates a more homogenous murine pneumonia, facilitating analysis of mutant strains and treatment regimens.

Administration, Inhalation↗
PubMed2004

In vitro interactions between antifungals and immunosuppressants against Aspergillus fumigatus isolates from transplant and nontransplant patients.

We performed in vitro antifungal checkerboard testing on 12 Aspergillus fumigatus clinical isolates (6 transplant recipients and 6 nontransplant patients) with three antifungal agents (amphotericin B, voriconazole, and caspofungin) and three immunosuppressants (FK506, cyclosporine, and rapamycin). We were not able to detect a difference in calcineurin inhibitor antifungal activity against isolates from transplant recipients and nontransplant patients.

Amphotericin B↗
PubMed2004

In vitro interactions between antifungals and immunosuppressants against Aspergillus fumigatus.

The optimal treatment for invasive aspergillosis remains elusive, despite the increased efficacy of newer agents. The immunosuppressants cyclosporine (CY), tacrolimus (FK506), and sirolimus (formerly called rapamycin) exhibit in vitro and in vivo activity against Candida albicans, Cryptococcus neoformans, and Saccharomyces cerevisiae, including fungicidal synergy with azole antifungals. We report here that both FK506 and CY exhibit a clear in vitro positive interaction with caspofungin against Aspergillus fumigatus by disk diffusion, microdilution checkerboard, and gross and microscopic morphological analyses. Microscopic morphological analyses indicate that the calcineurin inhibitors delay filamentation, and in combination with caspofungin there is a positive interaction. Our findings suggest a potential role for combination therapy with calcineurin pathway inhibitors and existing antifungal agents to augment activity against A. fumigatus.

Antifungal Agents↗
PubMed2004

Gpr1, a putative G-protein-coupled receptor, regulates morphogenesis and hypha formation in the pathogenic fungus Candida albicans.

In response to various extracellular signals, the morphology of the human fungal pathogen Candida albicans switches from yeast to hypha form. Here, we report that GPR1 encoding a putative G-protein-coupled receptor and GPA2 encoding a Galpha subunit are required for hypha formation and morphogenesis in C. albicans. Mutants lacking Gpr1 (gpr1/gpr1) or Gpa2 (gpa2/gpa2) are defective in hypha formation and morphogenesis on solid hypha-inducing media. These phenotypic defects in solid cultures are suppressed by exogenously added dibutyryl-cyclic AMP (dibutyryl-cAMP). Biochemical studies also reveal that GPR1 and GPA2 are required for a glucose-dependent increase in cellular cAMP. An epistasis analysis indicates that Gpr1 functions upstream of Gpa2 in the same signaling pathway, and a two-hybrid assay reveals that the carboxyl-terminal tail of Gpr1 interacts with Gpa2. Moreover, expression levels of HWP1 and ECE1, which are cAMP-dependent hypha-specific genes, are reduced in both mutant strains. These findings support a model that Gpr1, as well as Gpa2, regulates hypha formation and morphogenesis in a cAMP-dependent manner. In contrast, GPR1 and GPA2 are not required for hypha formation in liquid fetal bovine serum (FBS) medium. Furthermore, the gpr1 and the gpa2 mutant strains are fully virulent in a mouse infection. These findings suggest that Gpr1 and Gpa2 are involved in the glucose-sensing machinery that regulates morphogenesis and hypha formation in solid media via a cAMP-dependent mechanism, but they are not required for hypha formation in liquid medium or during invasive candidiasis.

Animals↗
PubMed2004

Identification of Cryptococcus neoformans temperature-regulated genes with a genomic-DNA microarray.

The ability to survive and proliferate at 37 degrees C is an essential virulence attribute of pathogenic microorganisms. A partial-genome microarray was used to profile gene expression in the human-pathogenic fungus Cryptococcus neoformans during growth at 37 degrees C. Genes with orthologs involved in stress responses were induced during growth at 37 degrees C, suggesting that a conserved transcriptional program is used by C. neoformans to alter gene expression during stressful conditions. A gene encoding the transcription factor homolog Mga2 was induced at 37 degrees C and found to be important for high-temperature growth. Genes encoding fatty acid biosynthetic enzymes were identified as potential targets of Mga2, suggesting that membrane remodeling is an important component of adaptation to high growth temperatures. mga2Delta mutants were extremely sensitive to the ergosterol synthesis inhibitor fluconazole, indicating a coordination of the synthesis of membrane component precursors. Unexpectedly, genes involved in amino acid and pyrimidine biosynthesis were repressed at 37 degrees C, but components of these pathways were found to be required for high-temperature growth. Our findings demonstrate the utility of even partial-genome microarrays for delineating regulatory cascades that contribute to microbial pathogenesis.

Cryptococcus neoformans↗
PubMed2004

Aspergillus fumigatus empyema, arthritis, and calcaneal osteomyelitis in a lung transplant patient successfully treated with posaconazole.

A 64-year-old male with Aspergillus fumigatus infection that had disseminated from the lung to the ankle and adjacent bone was treated successfully with posaconazole after therapy with itraconazole and amphotericin B lipid complex failed. Marked clinical improvement occurred within 6 weeks of initiation of posaconazole therapy; after 6 months, infection had resolved at all sites. The patient has had no recurrence of infection.

Antifungal Agents↗
PubMed2004

Interlaboratory comparison of results of susceptibility testing with caspofungin against Candida and Aspergillus species.

Seventeen laboratories participated in a study of interlaboratory reproducibility with caspofungin microdilution susceptibility testing against panels comprising 30 isolates of Candida spp. and 20 isolates of Aspergillus spp. The laboratories used materials supplied from a single source to determine the influence of growth medium (RPMI 1640 with or without glucose additions and antibiotic medium 3 [AM3]), the same incubation times (24 h and 48 h), and the same end point definition (partial or complete inhibition of growth) for the MIC of caspofungin. All tests were run in duplicate, and end points were determined both spectrophotometrically and visually. The results from almost all of the laboratories for quality control and reference Candida and Aspergillus isolates tested with fluconazole and itraconazole matched the NCCLS published values. However, considerable interlaboratory variability was seen in the results of the caspofungin tests. For Candida spp. the most consistent MIC data were generated with visual "prominent growth reduction" (MIC(2)) end points measured at 24 h in RPMI 1640, where 73.3% of results for the 30 isolates tested fell within a mode +/- one dilution range across all 17 laboratories. MIC(2) at 24 h in RPMI 1640 or AM3 also gave the best interlaboratory separation of Candida isolates of known high and low susceptibility to caspofungin. Reproducibility of MIC data was problematic for caspofungin tests with Aspergillus spp. under all conditions, but the minimal effective concentration end point, defined as the lowest caspofungin concentration yielding conspicuously aberrant hyphal growth, gave excellent reproducibility for data from 14 of the 17 participating laboratories.

Antifungal Agents↗
PubMed2004

Novel modes of antifungal drug administration.

Administration of antifungals by routes other than that for which the agent was designed or approved have been utilised in attempts to provide directed therapy, reduce adverse effects and improve drug penetration into selected infection sites, such as the central nervous system, lungs and peritoneum. The most widely investigated agent utilising a novel method of drug delivery is amphotericin B. Dose forms for this agent include topicals (aerosol, nasal spray, irrigations, pastes, absorbable sponges, impregnated bone cement and gelatin), oral dosage forms (solutions, suspensions, tablets and so on) and ophthalmic preparations (drops, ointments and injections). Amphotericin B has been administered by routes such as oral, endobronchial, intrathecal, intracisternal, intra-articular, intraperitoneal, ophthalmic and as an antibiotic 'line lock'. Nystatin has been administered as an aerosol, percutaneous paste and bladder washes. Azoles, such as miconazole, fluconazole, ketoconazole and posaconazole, have been administered by novel methods but to a lesser degree. Most of these reports involve miconazole. The dose forms and routes of administration for azoles have included irrigants (bladder, joint), ophthalmic preparations (eye drops, intraocular injections, ointments), impregnated bone cement, endobronchial and intrathecal administration. Finally, both methylene blue (bladder washes) and flucytosine (peritoneal lavage, ophthalmic eye drops) have also been employed. Adequate evaluations of both the safety and efficacy of these therapies are most often hindered by prior or concomitant antifungal therapies, comorbidities and the lack of controlled clinical trials. In addition, the availability of newer treatment options, which demonstrate significant improvement in drug distribution and treatment-related adverse effects make many such novel modes of administration less practical or necessary. In contrast, the inhalation of antifungal aerosols, such as amphotericin B, is rapidly becoming a viable prophylactic option.

Antifungal Agents↗
PubMed2004

Recent advances in antifungal pharmacotherapy for invasive fungal infections.

Invasive fungal infections carry significant morbidity and mortality. Candida species have become one of the most frequent causes of bloodstream infections, and infections caused by molds such as Aspergillus are becoming more frequent in immunocompromised patients. As this population grows, more invasive fungal infections can be anticipated. In the past, treatment options have been limited for many of these infections due to toxicity and efficacy concerns with the available antifungals. Fortunately, the past few years have brought exciting developments in antifungal pharmacotherapy. Lipid-based formulations of amphotericin B were introduced in the 1990s to attenuate adverse effects caused by amphotericin B deoxycholate (Fungizone, Bristol-Myers Squibb). Most recently, the echinocandins have been added to our antifungal regimen with the introduction of caspofungin (Cancidas, Merck and Co.) and voriconazole (Vfend, Pfizer), a new triazole, has come to market. The introduction of the echinocandins has invigorated the discussion about combination antifungal therapy. Evidence-based studies using these new agents are accumulating, and they are assuming important roles in the pharmacotherapy of invasive fungal infections in seriously ill and complex patients.

Amphotericin B↗
PubMed2004

Management of invasive mycoses in hematology patients: current approaches.

Candidiasis and aspergillosis are the most common fungal infections in hematopoietic stem cell transplant recipients and other hematology/oncology patients. Strategies for reducing the morbidity and mortality associated with these infections include antifungal prophylaxis, empiric therapy in patients with persistent fever and neutropenia, and preemptive therapy. Antifungal therapies include amphotericin B deoxycholate, lipid formulations of amphotericin B, the triazoles (fluconazole, itraconazole, and voriconazole), and the echinocandins (caspofungin and the investigational agents micafungin and anidulafungin). Fluconazole is a reasonable choice for the treatment of invasive candidiasis if the patient has not previously received a triazole and the institution has a low incidence of triazole resistance. If resistance is a concern, an echinocandin, such as caspofungin, is an appropriate option. Voriconazole may be the initial choice in most patients with invasive aspergillosis. If patients are intolerant of or refractory to conventional therapy, effective alternatives include a lipid formulation of amphotericin B or an echinocandin.

Amphotericin B↗
PubMed2004

Use of newer antifungal therapies in clinical practice: what do the data tell us?

Considering the significant morbidity and mortality associated with invasive fungal infections in immunocompromised patients, it is particularly important to make the diagnosis as early as possible and to make best use of the available antifungal drugs for prophylaxis and treatment. The newer antifungal drugs include the lipid products of amphotericin B, such as amphotericin B lipid complex (ABLC) and liposomal amphotericin B; voriconazole (a triazole); and caspofungin (an echinocandin). ABLC and liposomal amphotericin B are as effective as amphotericin B deoxycholate but are less nephrotoxic; ABLC is probably the drug of choice for zygomycosis. Voriconazole is approved for use in the treatment of invasive aspergillosis and may have a role in preventing breakthrough fungal infections in patients with persistent fever and neutropenia. Caspofungin is effective against both invasive aspergillosis and invasive candidiasis.

Amphotericin B↗
PubMed2004

Antifungal resistance: the clinical front.

The emergence of resistance and changes in the spectrum of Candida infections have led to an increased interest in susceptibility testing of antifungal drugs. Such testing may be particularly useful in patients with invasive candidiasis who have been previously treated with azole antifungals, those whose infections are not responding to treatment, and those with infections caused by non-albicans species of Candida. The choice of a specific antifungal depends on the clinical status of the patient, the relative toxicity and efficacy of the drug in the given patient population, the infecting species and antifungal susceptibility of the isolate, and the patient's prior exposure to antifungal agents. Infectious Diseases Society of America recommendations for the initial management of candidemia and acute disseminated candidiasis include an azole, caspofungin, amphotericin B (AmB), or a combination of fluconazole plus AmB. Caspofungin and voriconazole show good activity against most Candida species and may be good alternatives for patients with Candida glabrata and Candida krusei infections and for those with relapsing infections.

Amphotericin B↗
PubMed2003

Candidemia in women with breast carcinoma treated with high-dose chemotherapy and autologous bone marrow transplantation.

BACKGROUND: Invasive fungal infections, including candidemia, pose a major threat to patients with impaired immune defenses, including bone marrow transplantation (BMT) recipients. During 1992-1997, 845 women with multiple lymph node positive or metastatic breast carcinoma underwent high-dose chemotherapy (HDC) and subsequent autologous BMT at Duke University Medical Center. No systemic antifungal prophylaxis was administered. The purpose of the current study was to evaluate the risk and long-term outcome of candidemia in this patient population. METHODS: Clinical data were collected on patients with candidemia, and a group of age-matched control patients were identified who underwent HDC and BMT for breast carcinoma in the same time period. The difference in crude mortality between these two groups was used to calculate the attributable mortality of candidemia. The genetic relatedness of the fungal blood stream isolates was investigated by DNA fingerprinting. Antifungal susceptibility testing was performed using serial microdilution. RESULTS: Twenty-nine of 845 women developed candidemia (3.4%). The crude mortality of women with candidemia was 35% at 90 days after transplantation but 11% among women in the matched control group who were without infection (P = 0.01), for an attributable mortality rate of 24%. The most common pathogen was Candida tropicalis (50%), followed by Candida albicans (23%). The mortality was highest for women who were infected with C. albicans, followed by C. tropicalis, and other Candida species (P = 0.037). DNA fingerprinting of the yeasts revealed genetic heterogeneity in all species. However, 9 of 15 C. tropicalis isolates had identical DNA fingerprint profiles, suggesting spread of this genotype from a common source. All yeast isolates were susceptible to amphotericin B, and 20 of 30 isolates were susceptible to <or= 8 microg/mL of fluconazole. CONCLUSIONS: Candidemia was relatively infrequent after HDC and autologous BMT in women with for multiple lymph node positive or metastatic breast carcinoma. This was true even in the absence of systemic antifungal prophylaxis. The mortality attributable to candidemia in this patient population was 24% and was higher among patients who were infected by C. albicans compared with patients who were infected by other Candida, non-albicans species.

Adult↗
PubMed2003

Voriconazole treatment for less-common, emerging, or refractory fungal infections.

Treatments for invasive fungal infections remain unsatisfactory. We evaluated the efficacy, tolerability, and safety of voriconazole as salvage treatment for 273 patients with refractory and intolerant-to-treatment fungal infections and as primary treatment for 28 patients with infections for which there is no approved therapy. Voriconazole was associated with satisfactory global responses in 50% of the overall cohort; specifically, successful outcomes were observed in 47% of patients whose infections failed to respond to previous antifungal therapy and in 68% of patients whose infections have no approved antifungal therapy. In this population at high risk for treatment failure, the efficacy rates for voriconazole were 43.7% for aspergillosis, 57.5% for candidiasis, 38.9% for cryptococcosis, 45.5% for fusariosis, and 30% for scedosporiosis. Voriconazole was well tolerated, and treatment-related discontinuations of therapy or dose reductions occurred for <10% of patients. Voriconazole is an effective and well-tolerated treatment for refractory or less-common invasive fungal infections.

Adolescent↗
PubMed2003

Newer antifungal therapy for emerging fungal pathogens.

As the number of immunocompromised patients increases, there is a concomitant increase in the number and diversity of fungal infections. Fungi that were once considered harmless or contaminants are now pathogenic in the immunocompromised host. Often these emerging pathogens are indistinguishable from the more familiar fungal infections; however, they are generally more recalcitrant to conventional antifungal therapies. With the antifungal armamentarium now expanding, the clinician now has many more options for these difficult-to-treat mycoses. We review many of the newer antifungal agents (second-generation triazoles, echinocandins, etc.) as therapeutic options for the recently emerging fungal pathogens.

Animals↗