Biomedical subjects

John R Perfect

Publications and source records attributed to John R Perfect.

At least 37 records · Page 2Linked to original sources

PubMed2005

Candida glabrata fungemia in transplant patients receiving voriconazole after fluconazole.

The clinical impact of voriconazole resistance in Candida glabrata is not well described. Five hematopoietic stem cell transplant recipients that developed breakthrough Candida glabrata bloodstream infections while receiving voriconazole are described and the clinical management and susceptibility profiles of their isolates are reported. All patients were markedly immunosuppressed, and in all cases, voriconazole use was preceded by prolonged fluconazole exposure (median 60 days); median voriconazole exposure prior to candidemia was 48 days. Isolates from 4 patients were shown to be resistant to fluconazole and itraconazole when tested in vitro; these same isolates had MICs to voriconazole and posaconazole > or = 2 microg/ml. Clinical failure to voriconazole may result from deficits in host defense, retained infected foci, and adaptation of the organism to environmental pressures, the specific sequence and mechanisms of which warrant further study. Clinicians must maintain a high index of suspicion for these infections in highly susceptible hosts despite voriconazole therapy, particularly when voriconazole use is preceded by prolonged fluconazole exposure.

Adolescent↗

PubMed2005

Cryptococcus neoformans: a sugar-coated killer with designer genes.

Cryptococcus neoformans has become a common central nervous system pathogen as the immunocompromised populations enlarge world-wide. This encapsulated yeast has significant advantages for the study of fungal pathogenesis and these include: (1) a clinically important human pathogen; (2) a tractable genetic system; (3) advanced molecular biology foundation; (4) understanding of several virulence phenotypes; (5) well-studied pathophysiology; and (6) robust animal models. With the use of a sequenced genome and site-directed mutagenesis to produce specific null mutants, the virulence composite of C. neoformans has begun to be identified one gene at a time. Studies into capsule production, melanin synthesis, high temperature growth, metabolic pathways and a variety of signaling pathways have led to understandings of what makes this yeast a pathogen at the molecular level. Multiple principles of molecular pathogenesis have been demonstrated in virulence studies with C. neoformans. These include evolutionary differences between the varieties of C. neoformans in their genes for virulence, quantitative impact of genes on the virulence composite, species and site-specific importance of a virulence gene, gene expression correlation with its functional importance or phenotype and the impact of a pathogenesis gene on the host immune response. C. neoformans has now become a primary model to study molecular fungal pathogenesis with the goal of identifying drug targets or vaccine strategies.

Animals↗

PubMed2005

Treatment of non-Aspergillus moulds in immunocompromised patients, with amphotericin B lipid complex.

An assessment was made of the efficacy and renal safety of amphotericin B lipid complex (ABLC) in the treatment of patients with invasive fungal infections caused by moulds other than Aspergillus species, on the basis of a retrospective analysis of data from the Collaborative Exchange of Antifungal Research (CLEAR) database. Data from CLEAR for 64 patients with zygomycosis were published previously. The database was further queried and yielded results for 28 patients with fusariosis and 84 patients infected with other non-Aspergillus moulds. Of 26 patients with fusariosis whose results could be evaluated, 46% (n = 12) were cured or improved, and an additional 12% (n = 3) were stable. Of 79 patients infected with other non-Aspergillus moulds whose results could be evaluated, 61% (n = 48) were cured or improved, and an additional 15% (n = 12) were stable. In an area with little guidance for therapy, the CLEAR data indicate that ABLC can be an effective broad-spectrum treatment choice for several invasive and refractory non-Aspergillus mould infections.

Adolescent↗

PubMed2005

Successful use of amphotericin B lipid complex in the treatment of cryptococcosis.

The efficacy and renal safety of amphotericin B lipid complex (ABLC) injection were assessed in 106 patients with cryptococcal infection. Eighty-three patients (78%) had a central nervous system (CNS) infection. Of these patients, 20 initiated azole therapy concomitantly with ABLC therapy, and 7 had received prior azole therapy, which continued during administration of ABLC. Clinical response (cured or improved) was achieved in 67 (66%) of 101 patients whose results could be evaluated. Response rates were 65% (51/78) for patients with a CNS infection and 70% (16/23) for patients without a CNS infection. The response rate for patients with HIV infection was 58% (30/52). Response rates were 56% (19/34) for patients who were refractory to prior antifungal therapy, 65% (11/17) for patients who were intolerant of prior antifungal therapy, 60% (3/5) for patients with underlying renal disease who received prior antifungal therapy, 76% (25/33) for patients with underlying renal disease who did not receive prior antifungal therapy, and 73% (8/11) for patients with no renal disease who did not receive prior antifungal therapy. A mean serum creatinine level decrease of 0.02 mg/dL occurred. ABLC was an effective treatment for cryptococcal infection in immunocompromised patients.

Adult↗

PubMed2005

Is it time to abandon the use of amphotericin B bladder irrigation?

In this article, we review the issues surrounding funguria and its management. With this background, the value of bladder irrigation with amphotericin B for the management of funguria is directly examined. Amphotericin B bladder irrigation is used frequently in clinical practice. Although its use is not standardized, there are multiple studies that attempt to show the impact on funguria management. These bladder irrigations have been used either for treatment of funguria or (less commonly) as a diagnostic test in attempts to identify upper urinary tract disease. Despite their widespread therapeutic use and relative safety, it is not clear from our experience and a review of the literature that amphotericin B bladder irrigations have any diagnostic or therapeutic value. The patient may be best served by removal of the urinary catheter, if possible, rather than by instillation of bladder irrigation with amphotericin B.

Amphotericin B↗

PubMed2005

Cytochrome c peroxidase contributes to the antioxidant defense of Cryptococcus neoformans.

Cryptococcus neoformans is an opportunistic pathogen and the leading cause of fungal meningitis. To survive within the host, this organism must be able to protect itself from oxidative stress. Cytochrome c peroxidase (Ccp1) is a mitochondrial antioxidant that catalyzes the degradation of hydrogen peroxide. In the present study, we characterized the contribution of the C. neoformans Ccp1 to antioxidant defense and for virulence. Consistent with studies of Ccp1 function in Sacchromyces cerevisiae, we found that Ccp1 contributes to resistance against exogenous oxidative stress in vitro. However, the oxidative stress phenotype does not diminish the virulence of ccp1 mutant strains in a murine model of C. neoformans disease. These results suggest that Ccp1 is involved in a complex system of protection against exogenous oxidative stress and that the elimination of this component of the antioxidant defense system does not diminish the virulence of C. neoformans.

Adaptation, Physiological↗

PubMed2005

Phenotypic and genotypic evaluation of fluconazole resistance in vaginal Candida strains isolated from HIV-infected women from Brazil.

We conducted a study to determine the antifungal susceptibility of vaginal Candida isolates from HIV-infected Brazilian women. Among 127 women enrolled, positive cultures for yeast were obtained from 31 of 38 (81%) women with symptomatic vulvovaginitis, and from 41 of 89 (46%) asymptomatic women. Susceptibility testing demonstrated 11 of the 72 isolates had either resistance or dose-dependent susceptibility to azole drugs, including four Candida albicans strains. Expression of the MDR1, CDR1, CDR2 and ERG11 genes was evaluated in all of the C. albicans isolates, and all four of the strains with reduced susceptibility to fluconazole had increased expression of CDR1 as compared to the fluconazole-sensitive strains. No increased expression of the other genes was identified. This large survey of Candida isolates from HIV-infected women from Brazil demonstrates that reduced susceptibility to azoles occurs at a low frequency among vaginal yeast isolates, and when present in C. albicans, azole resistance is associated with increased expression of CDR1.

AIDS-Related Opportunistic Infections↗

PubMed2005

Novel use of a swimming pool biocide in the treatment of a rare fungal mastoiditis.

OBJECTIVE: To describe an extremely rare fungal mastoiditis caused by Lecythophora hoffmannii, its recalcitrant behavior to therapy, and eventual successful treatment with adjunctive therapy using polyhexamethylene biguanide (a common swimming pool biocide). STUDY DESIGN: Case report and review of literature of human Lecythophora hoffmannii infections. METHODS: Medline database was searched using the keywords Lecythophora and hoffmannii. All articles that described Lecythophora hoffmannii as the cause of human infection at any site were identified. Literature and patient's records were considered for complete data review and extraction. RESULTS: We present the second known case in the literature of a human infection with Lecythophora hoffmannii. We also present the process to definitively identify and then to successfully eradicate this unusual fungal infection using polyhexamethylene biguanide as adjunctive treatment. CONCLUSIONS: Successful treatment of a chronic Lecythophora hoffmannii fungal mastoiditis involved a combination of radical surgical removal of all apparent infected tissue along with local treatments with polyhexamethylene biguanide, a common swimming pool biocide agent under the brand name Baquacil (Avecia, Manchester, United Kingdom). Given the prolonged course of treatment, this report particularly stresses the importance of concurrent surgery combined with creative local antimicrobial therapy to eliminate an unusual fungal infection in an immunocompetent host.

Biguanides↗

PubMed2005

Cryptococcus neoformans mitochondrial superoxide dismutase: an essential link between antioxidant function and high-temperature growth.

Manganese superoxide dismutase is an essential component of the mitochondrial antioxidant defense system of most eukaryotes. In the present study, we used a reverse-genetics approach to assess the contribution of the Cryptococcus neoformans manganese superoxide dismutase (Sod2) for antioxidant defense. Strains with mutations in the SOD2 gene exhibited increased susceptibility to oxidative stress as well as poor growth at elevated temperatures compared to isogenic wild-type strains. The sod2Delta mutants were also avirulent in a murine model of inhaled cryptococcosis. Reconstitution of a sod2Delta mutant restored Sod2 activity, eliminated the oxidative stress and temperature-sensitive (ts) phenotypes, and complemented the virulence phenotype. Characterization of the ts phenotype revealed a dependency between Sod2 antioxidant activity and the ability of C. neoformans cells to adapt to growth at elevated temperatures. The ts phenotype could be suppressed by the addition of either ascorbic acid (10 mM) or Mn salen (200 muM) at 30 degrees C, but not at 37 degrees C. Furthermore, sod2Delta mutant cells that were incubated for 24 h at 37 degrees C under anaerobic, but not aerobic, conditions were viable when shifted to the permissive conditions of 25 degrees C in the presence of air. These data suggest that the C. neoformans Sod2 is a major component of the antioxidant defense system in this human fungal pathogen and that adaptation to growth at elevated temperatures is also dependent on Sod2 activity.

Animals↗

PubMed2005

Cryptococcus neoformans {alpha} strains preferentially disseminate to the central nervous system during coinfection.

Cryptococcus neoformans is a fungal pathogen that has evolved over the past 40 million years into three distinct varieties or sibling species (gattii, grubii, and neoformans). Each variety manifests differences in epidemiology and disease, and var. grubii strains are responsible for the vast majority of human disease. In previous studies, alpha strains were more virulent than congenic a strains in var. neoformans, whereas var. grubii congenic a and alpha strains exhibited equivalent levels of virulence. Here the role of mating type in the virulence of var. grubii was further characterized in a panel of model systems. Congenic var. grubii a and alpha strains had equivalent survival rates when cultured with amoebae, nematodes, and macrophages. No difference in virulence was observed between a and alpha congenic strains in multiple inbred-mouse genetic backgrounds, and there was no difference in accumulations in the central nervous system (CNS) late in infection. In contrast, during coinfections, a and alpha strains are equivalent in peripheral tissues but alpha cells have an enhanced predilection to penetrate the CNS. These studies reveal the first virulence difference between congenic a and alpha strains in the most common pathogenic variety and suggest an explanation for the prevalence of alpha strains in clinical isolates.

Animals↗

PubMed2005

Immunology of infection caused by Cryptococcus neoformans.

Cryptococcus neoformans is an opportunistic fungal pathogen that may lead to life-threatening meningoencephalitis and pulmonary infections in immunosuppressed hosts. The lack of an effective fungicidal regimen and the development of antifungal resistant strains suggest that continued investigation is necessary to devise immunotherapeutic strategies and/or drug targets to combat C. neoformans infections. Studies to date involve investigating the host-pathogen interaction of cryptococcal infections through the genetic manipulation of the yeast, as well as the characterization of the host immune response. Macrophage phagocytosis and killing assays have proven to be invaluable tools in evaluating the putative effects of the genetic manipulation of C. neoformans strains on the virulence composite of the yeast. In addition, the assay is used to assess the efficacy of various immunotherapeutic agents (i.e., antibodies and cytokines) to enhance this cell-based antifungal activity. The purpose of this chapter is to provide a brief overview on host immunity to C. neoformans infection and, in addition, describe a protocol for performing macrophage phagocytosis and killing assays with C. neoformans and its mutants.

Animals↗

PubMed2005

Liposomal amphotericin B: clinical experience and perspectives.

While amphotericin B deoxycholate (Fungizone, Apothecon Pharmaceuticals) has been considered by many to be the gold standard for the treatment for numerous invasive fungal infections for over 45 years, toxicities associated with its use often necessitate treatment modification or discontinuation. Lipid-based formulations, including liposomal amphotericin B (AmBisome, Fujisawa Healthcare, Inc.), were developed to decrease many of these toxicities while retaining broad antifungal spectrum and potency of amphotericin B. In clinical trials, liposomal amphotericin B has demonstrated efficacy comparable to that of amphotericin B deoxycholate while reducing the incidence of treatment-related nephrotoxicity, electrolyte-wasting, and infusion-related reactions. In addition, recent clinical trials have also compared liposomal amphotericin B with other antifungal classes. Acquisition costs of liposomal amphotericin B are substantially higher than those of amphotericin B deoxycholate and other antifungals. While pharmacoeconomic analyses consider outcomes and other treatment-related costs, they have yet to clearly demonstrate the cost-effectiveness of liposomal amphotericin B when compared with amphotericin B deoxycholate or other antifungal agents. This review will focus primarily on recent liposomal amphotericin B experience and attempt to put its use into perspective considering other available antifungal agents.

Amphotericin B↗

PubMed2004

A meta-analysis of medical versus surgical therapy for Candida endocarditis.

OBJECTIVES: The optimal management of Candida infective endocarditis (IE) is unknown. METHODS: We reviewed all 879 cases of Candida IE reported from 1966-2002 in the peer-reviewed literature to better understand the role of medical and surgical therapies. This review included 163 patients from 105 reports that met our inclusion criteria: 31 cases treated with antifungal monotherapy, 25 cases treated with medical antifungal combination therapy, and 107 cases treated with adjunctive surgical plus medical antifungal therapy. We also used meta-analytic techniques to evaluate 22 observational case-series (72 patients) of the 105 reports with two or more patients with definite Candida IE. RESULTS: We found that in patients who underwent adjunctive surgery there was a lower reported proportion of deaths [prevalence odds ratio (POR)=0.56; 95% confidence interval (CI)=0.16, 1.99)]. Higher mortality was noted in patients treated prior to 1980 (POR=2.03; 95% CI=0.55, 7.61), treated with antifungal monotherapy (POR=1.49; 95% CI=0.39, 5.81), infected with Candida parapsilosis (POR=1.51; 95% CI=0.41, 5.52), or with left-sided endocarditis (POR=2.36; 95% CI=0.55, 10.07). CONCLUSIONS: Medical antifungal therapy of Candida IE is poorly characterized, and recent antifungal developments lend promise for those patients who cannot undergo surgery.

Adolescent↗

PubMed2004

Design of aerosolized amphotericin b formulations for prophylaxis trials among lung transplant recipients.

BACKGROUND: Emphasis has been placed on the need for antifungal prophylaxis when transplanted organs are directly exposed to the environment. In lung transplantation, one strategy for prevention has been aerosolization of polyenes into the lung. Despite widespread use of amphotericin B aerosols, there are still few studies on how to validate their effectiveness or optimize pharmacokinetics. METHODS: We compared results of several of our own studies of lung transplant recipients receiving formulations of amphotericin B with results of other studies. RESULTS: Recent aerosol studies suggest that aerosols of a lipid formulation of amphotericin B are safe and better tolerated than is amphotericin B deoxycholate. Their use in prophylaxis is associated with very few pulmonary fungal infections. CONCLUSION: This safe drug delivery at a local body site to directly protect the transplanted organ without systemic antifungal drug exposure is attractive from a cost and toxicity standpoint. However, careful multicenter, comparative studies are still needed to ensure that this strategy is consistently successful.

Aerosols↗

PubMed2004

Cryptococcus neoformans mitochondrial genomes from serotype A and D strains do not influence virulence.

Cryptococcus neoformans is an encapsulated pathogenic yeast producing meningoencephalitis. Two primary strains in genetic studies, serotype A H99 and serotype D JEC21, possess dramatic differences in virulence. Since it has been shown that mitochondrial gene expression is prominent at the site of the infection and there are significant differences between mitochondrial gene structure and regulation between the serotype A and D strains, this study used AD hybrids to move serotype A and D mitochondria under different genomic influences. When the serotype D MATa strain is involved in the mating crosses, there is uniparental transmission of mitochondrial DNA, but with the serotype A MATa strain, mitochondrial DNA can be inherited from either parent and recombination in the mitochondrial genome may also occur. In virulence studies between serotype A and D strains, it was found that the primary genetic control of the virulence composite for growth in the central nervous system is encoded in the nuclear DNA and not through mitochondrial DNA.

Animals↗

PubMed2004

Infections due to Aspergillus terreus: a multicenter retrospective analysis of 83 cases.

Current in vitro and in vivo data indicate that invasive aspergillosis due to Aspergillus terreus is resistant to treatment with amphotericin B. Because little clinical data are available to guide therapy, we performed a retrospective cohort study of cases of invasive A. terreus infections from 1997-2002 to determine whether the use of voriconazole, compared with use of other antifungal therapies, led to an improved patient outcome. We analyzed a total of 83 cases of proven or probable invasive A. terreus infection (47% and 53%, respectively). A total of 66.3% of patients (55 of 83) died during management of IA, with 55.8% mortality (19 of 34 patients) in the voriconazole group and 73.4% mortality (36 of 49) in the group that received therapy with other antifungals. By use of Cox proportional hazards modeling, decreased mortality at 12 weeks was observed in those patients who received voriconazole (hazard ratio, 0.29; 95% CI, 0.15-0.56). Voriconazole is likely to be a better treatment choice for A. terreus infection than is a polyene.

Antifungal Agents↗

PubMed2004

Comparative safety of amphotericin B lipid complex and amphotericin B deoxycholate as aerosolized antifungal prophylaxis in lung-transplant recipients.

BACKGROUND: Aerosolized administrations of amphotericin B deoxycholate (AmBd) and amphotericin B lipid complex (ABLC) in lung transplant recipients were compared for safety and tolerability. The incidence of invasive fungal infections in patients receiving aerosolized amphotericin B formulations as sole prophylaxis was determined. METHODS: A prospective, randomized (1:1), double-blinded trial was conducted with 100 subjects. AmBd and ABLC were administered postoperatively by nebulizer at doses of 25 mg and 50 mg, respectively, which were doubled in mechanically ventilated patients. The planned treatment was once every day for 4 days, then once per week for 7 weeks. Treatment-related adverse events and invasive fungal infections were quantitated for 2 months after study drug initiation. RESULTS: Intent-to-treat analysis revealed study drug was discontinued for intolerance in 6 of 49 (12.2%) and 3 of 51 (5.9%) patients in the AmBd- and ABLC-treated groups, respectively (p=0.313). Subjects receiving AmBd were more likely to have experienced an adverse event (odds ratio 2.16, 95% confidence interval 1.10, 4.24, p=0.02). Primary prophylaxis failure within 2 months of study drug initiation was observed in 7 of 49 (14.3%) AmBd-treated patients and 6 of 51 (11.8%) ABLC-treated patients. No fungal pneumonias were observed. Only two (2%) patients experienced documented primary prophylaxis failure with Aspergillus infections within the follow-up period. CONCLUSIONS: Both aerosol AmBd and ABLC appear to be associated with a low rate of invasive pulmonary fungal infection in the early posttransplant period. Patients receiving ABLC were less likely to experience a treatment-related adverse event.

Adolescent↗

PubMed2004

Urease expression by Cryptococcus neoformans promotes microvascular sequestration, thereby enhancing central nervous system invasion.

Our objective was to determine the role of the cryptococcal virulence factor urease in pulmonary-to-central nervous system, dissemination, invasion, and growth. C. neoformans H99, the urease knockout strain (ure1) derived from H99, and the urease restored strain ure1+URE1-1 were used for the studies. The absence of cryptococcal urease (ure1infection) resulted in significant protection from the high mortality observed in H99-infected mice. All H99-infected mice had extremely high cryptococcal loads in their brains at the time of death, whereas only two of six animals that died of ure1 infection had detectable C. neoformans in the brain. Histological analysis of the blood-to-brain invasion by C. neoformans H99 demonstrated wedging of the yeasts in small capillaries, altered structure of microvessel walls, formation of mucoid cysts initiated in the proximity of damaged microcapillaries, and the absence of an inflammatory response. Direct inoculation of H99, ure1, and ure1+URE1-1 into the brain demonstrated that urease was not required to grow in the brain. However, the dissemination patterns in the brain, spleen, and other organs after intravenous inoculation indicated that cryptococcal urease contributes to the central nervous system invasion by enhancing yeast sequestration within microcapillary beds (such as within the brain) during hematogenous spread, thereby facilitating blood-to-brain invasion by C. neoformans.

Animals↗