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J H Rex

Publications and source records attributed to J H Rex.

At least 37 records · Page 2Linked to original sources
PubMed2001

Differential antifungal activity of isomeric forms of nystatin.

When nystatin is placed in RPMI and other biological fluids, there is loss of pure nystatin, with the development of two distinguishable chromatographic peaks, 1 and 2. Peak 1 appears identical to commercially prepared nystatin. By nuclear magnetic resonance (NMR) and mass spectral analysis, peak 2 appears to be an isomer of peak 1. The isomers are quantitatively and fully interconvertible. Formation of peak 2 is accelerated at a pH of >7.0 and ultimately reaches a near 55:45 (peak 1/peak 2 ratio) mixture. We sought to determine the relative activities of peaks 1 and 2 against Candida spp. Peak 2 consistently showed higher MICs when it was the predominant form during the experiment. Time-kill analyses showed that peak 2 required > or =8 x the concentration of peak 1 to produce a modest and delayed killing effect, which was never of the same magnitude as that produced by peak 1. In both types of assays, the activity of peak 2 corresponded with intra-assay formation of peak 1. Both MIC measurements and time-kill analysis suggest that peak 2 has considerably less activity, if any at all, against Candida spp. Peak 2 may serve as a reservoir for peak 1.

Antifungal Agents↗
PubMed2001

Antifungal susceptibility testing: practical aspects and current challenges.

Development of standardized antifungal susceptibility testing methods has been the focus of intensive research for the last 15 years. Reference methods for yeasts (NCCLS M27-A) and molds (M38-P) are now available. The development of these methods provides researchers not only with standardized methods for testing but also with an understanding of the variables that affect interlaboratory reproducibility. With this knowledge, we have now moved into the phase of (i) demonstrating the clinical value (or lack thereof) of standardized methods, (ii) developing modifications to these reference methods that address specific problems, and (iii) developing reliable commercial test kits. Clinically relevant testing is now available for selected fungi and drugs: Candida spp. against fluconazole, itraconazole, flucytosine, and (perhaps) amphotericin B; Cryptococcus neoformans against (perhaps) fluconazole and amphotericin B; and Aspergillus spp. against (perhaps) itraconazole. Expanding the range of useful testing procedures is the current focus of research in this area.

Animals↗
PubMed2001

Lipid-based antifungal agents: current status.

Immunocompromised patients are well known to be predisposed to developing invasive fungal infections. These infections are usually difficult to diagnose and more importantly, the resulting mortality rate is high. The limited number of antifungal agents available and their high rate of toxicity are the major factors complicating the issue. However, the development of lipid-based formulations of existing antifungal agents has opened a new era in antifungal therapy. The best examples are the lipid-based amphotericin B preparations, amphotericin B lipid complex (ABLC; Abelcet), amphotericin B colloidal dispersion (ABCD; Amphotec or Amphocil), and liposomal amphotericin B (AmBisome). These formulations have shown that antifungal activity is maintained while toxicity is reduced. This progress is followed by the incorporation of nystatin into liposomes. Liposomal nystatin formulation is under development and studies of it have provided encouraging data. Finally, lipid-based formulations of hamycin, miconazole, and ketoconazole have been developed but remain experimental. Advances in technology of liposomes and other lipid formulations have provided promising new tools for management of fungal infections.

Amphotericin B↗
PubMed2001

Nystatin LF (Aronex/Abbott).

Nystatin LF (Nyotran) is a liposomal, intravenous nystatin formulation under development by Aronex, under license from the MD Anderson Cancer Research Center, as a systemic antifungal agent against strains including Aspergillus and Candida. Like amphotericin, nystatin is a polyene derivative that binds to ergosterol, a fungal cell membrane component, creating a pore in the membrane and thus killing the cell. Nystatin is an established antifungal agent, but is restricted to topical use as it is ineffective orally and severely toxic when administered iv [187583], [187589]. It has demonstrated good, broad in vitro antifungal activity against clinically relevant filamentous fungi [319465], including fungi resistant to fluconazole and amphotericin B products [264505], [2869821, [287790], 1289522]. The company is also conducting a phase III trial to evaluate its efficacy against cryptococcal meningitis [305531], [334156]. Aronex filed for approval of nystatin LF in Spain in December 1997 [272986] and expected to file an NDA in the US by the end of 1999 1311208], [342003]. However, in an effort to ensure that its US and European filings contained data from the phase III cryptococcal meningitis trial in its entirety, Aronex's marketing partner requested that all the 70-day data be gathered prior to unblinding this study. The filing had initially been based on interim data at the 14- and 21-day endpoint 1344887]. In September 2000, the company anticipated an NDA filing in the US in the fourth quarter of 2001 1382861], 1387947]. In December 1997, Aronex, together with Grupo Ferrer Internacional, filed an MAA in Spain seeking approval for Nyotran for the treatment of systemic fungal infections. Aronex intended to follow the filing with additional filings in other European countries 1272986]. In 1997, a commercialization agreement was signed with Ferrer for Spain and Portugal, with Aronex intending to form other such partnerships throughout Europe and Asia 1248346]. In November 1998, Aronex signed a licensing collaboration with Abbott Laboratories for the worldwide rights to nystatin LF [305531].

Antifungal Agents↗
PubMed2000

Practice guidelines for the treatment of candidiasis. Infectious Diseases Society of America.

Infections due to Candida species are the most common of the fungal infections. Candida species produce a broad range of infections, ranging from nonlife-threatening mucocutaneous illnesses to invasive process that may involve virtually any organ. Such a broad range of infections requires an equally broad range of diagnostic and therapeutic strategies. This document summarizes current knowledge about treatment of multiple forms of candidiasis and is the guideline of the Infectious Diseases Society of America (IDSA) for the treatment of candidiasis. Throughout this document, treatment recommendations are scored according to the standard scoring scheme used in other IDSA guidelines to illustrate the strength of the underlying data. The document covers 4 major topical areas. The role of the microbiology laboratory. To a greater extent than for other fungi, treatment of candidiasis can now be guided by in vitro susceptibility testing. The guidelines review the available information supporting current testing procedures and interpretive breakpoints and place these data into clinical context. Susceptibility testing is most helpful in dealing with infection due to non-albicans species of Candida. In this setting, especially if the patient has been treated previously with an azole antifungal agent, the possibility of microbiological resistance must be considered. Treatment of invasive candidiasis. In addition to acute hematogenous candidiasis, the guidelines review strategies for treatment of 15 other forms of invasive candidiasis. Extensive data from randomized trials are really available only for therapy of acute hematogenous candidiasis in the nonneutropenic adult. Choice of therapy for other forms of candidiasis is based on case series and anecdotal reports. In general, both amphotericin B and the azoles have a role to play in treatment. Choice of therapy is guided by weighing the greater activity of amphotericin B for some non-albicans species (e.g., Candida krusei) against the lesser toxicity and ease of administration of the azole antifungal agents. Flucytosine has activity against many isolates of Candida but is not often used. Treatment of mucocutaneous candidiasis. Therapy for mucosal infections is dominated by the azole antifungal agents. These drugs may be used topically or systemically and have been proven safe and efficacious. A significant problem with mucosal disease is the propensity for a small proportion of patients to suffer repeated relapses. In some situations, the explanation for such a relapse is obvious (e.g., relapsing oropharyngeal candidiasis in an individual with advanced and uncontrolled HIV infection), but in other patients the cause is cryptic (e.g., relapsing vaginitis in a healthy woman). Rational strategies for these situations are discussed in the guidelines and must consider the possibility of induction of resistance over time. Prevention of invasive candidiasis. Prophylactic strategies are useful if the risk of a target disease is sharply elevated in a readily identified group of patients. Selected patient groups undergoing therapy that produces prolonged neutropenia (e.g., some bone-marrow transplant recipients) or who receive a solid-organ transplant (e.g., some liver transplant recipients) have a sufficient risk of invasive candidiasis to warrant prophylaxis.

Adult↗
PubMed2000

Systematic root cause analysis of adverse drug events in a tertiary referral hospital.

BACKGROUND: Adverse drug events (ADEs) occur frequently, and serious ADEs are associated with mortality or prolonged morbidity. As many ADEs are preventable, identification and modification of systems and processes that permit ADEs has the potential to reduce the rate of ADEs. METHODS: Root cause analysis was systematically employed in a blame-free fashion to investigate the patterns of serious ADEs that occurred during a 29-month period at Hermann Hospital (Houston), and process improvements were implemented on the basis of these findings. The consistently nonpunitive responses to the results of the initial and subsequent root cause analyses was gradually seen, accepted, and ultimately embraced by the hospital staff. RESULTS: The most commonly identified root causes were environmental factors (for example, increased census, increased acuity, change of shift) and staffing issues (for example, personnel new to a unit). Policy changes that led to increased use of forcing or constraining functions (for example, removal of concentrated intravenous potassium solutions from floor stocks) and better personnel support (for example, early awareness and response to localized increases in census and acuity) were particularly effective. Although limited by our lack of active surveillance and not necessarily directly due to the process changes that we implemented, the rate of voluntarily reported serious ADEs/100,000 patient days decreased during this time from 7.2 to 4.0, a decline of 45% (p < 0.001). CONCLUSION: Systematic application of root cause analysis followed by implementation of process changes that target the underlying cause(s) of each event can be successfully implemented in a large hospital.

Adverse Drug Reaction Reporting Systems↗
PubMed2000

Quality control limits for broth microdilution susceptibility tests of ten antifungal agents.

Broth microdilution susceptibility tests of Candida species have now been standardized by the National Committee for Clinical Laboratory Standards (NCCLS). An eight-laboratory collaborative study was carried out in order to document reproducibility of tests of Candida parapsilosis ATCC 22019 and Candida krusei ATCC 6258 by the NCCLS method. Replicate broth microdilution tests were used to define control limits for 24- and 48-h MICs of amphotericin B, flucytosine, fluconazole, voriconazole, ketoconazole, itraconazole, caspofungin (MK 0991), ravuconazole (BMS 207147), posaconazole (SCH 56592), and LY 303366.

Antifungal Agents↗
PubMed2000

Deep Candida infections in the neutropenic and non-neutropenic host: an ISHAM symposium.

A symposium was held on May 8, 2000 to discuss the management of deep infections with Candida species. Among the findings discussed were the following. Candiduria is most often benign, though it occurs in patients with serious underlying diseases. Candida species are now the fourth most common cause of nosocomial bloodstream infections, usually arising from an intravenous catheter. Candida albicans represents only 50-60% of the isolates. There has been no change in the frequency of fluconazole resistance in C. albicans but some of the other species now being isolated from blood are constitutively more resistant to this drug. Nevertheless, for most non-neutropenic patients with candidemia, fluconazole is a reasonable choice for initial therapy. In the neutropenic patient, candidemia is now uncommon. Deep candida infections in neutropenic patients are usually being treated empirically with an amphotericin B formulation. Hepatosplenic candidiasis is usually detected only after recovery from neutropenia but can be suspected by imaging techniques. Improved diagnostic techniques for deep candidiasis in the neutropenic patient remain a critical requirement.

Antifungal Agents↗
PubMed2000

Mycoses in AIDS.

Major changes are occurring in the epidemiology of opportunistic infections (OI) in patients with acquired immune deficiency syndrome (AIDS) and treated with highly active antiretroviral therapy (HAART). A marked decrease of minor and major OI was observed and clinical resistance of thrush to antifungal agents became extremely rare. Primary and secondary prophylaxis against Pneumocystis carinii infections can be stopped; however, the situation is less clear for other OI such as cryptococcosis or endemic mycoses. The epidemiology is dramatically different in the countries which cannot afford the cost of HAART for the majority of patients, such as South Africa. These topics will be discussed in this paper.

AIDS-Related Opportunistic Infections↗
PubMed1999

Treatment of murine fusariosis with SCH 56592.

Doses of 10 to 100 mg of the azole antifungal agent SCH 5692/kg of body weight/day were studied in immunocompetent mice as therapy for systemic infection by Fusarium solani. Treatment was begun 1 h after intravenous infection and continued daily for 4 or 13 doses. Prolongation of survival and organ clearance were dependent on both the dose and the duration of SCH 56592 therapy, with the best results seen at 50 and 100 mg/kg/day. The results at the highest doses of SCH 56592 used (50 or 100 mg/kg/day) were comparable to those obtained with amphotericin B at 1 mg/kg/day. SCH 56592 has potential for therapy of systemic infections caused by F. solani.

Animals↗
PubMed1999

The trailing end point phenotype in antifungal susceptibility testing is pH dependent.

The interpretation of end points in azole antifungal drug susceptibility testing is problematic, in part due to incomplete growth inhibition of Candida species. Such trailing growth can cause the MICs of fluconazole for some isolates to be low (<1 microg/ml) after 24 h of growth but much higher (>64 microg/ml) after 48 h. Isolates having this type of growth have been described as having a low-high phenotype. Although these isolates would be considered resistant by current National Committee of Clinical Laboratory Standards definitions, growing evidence suggests that they are susceptible in vivo. To further characterize these isolates in vitro, microdilution susceptibility testing comparing the complex defined medium RPMI 1640 to a defined minimal medium (yeast nitrogen broth) was performed. Isolates having trailing growth in MOPS (morpholinepropanesulfonic acid)-buffered RPMI 1640 (pH 7.0) were found to have clear end points in the minimal medium at its native pH of 4.5. The pH of the medium influenced the low-high phenotype, as these same isolates trailed in minimal medium adjusted to a pH of >/=6.0 but did not trail in RPMI 1640 adjusted to a pH of </=5.0. This pH effect was independent of the medium buffering capacity, as trailing was decreased in both minimal medium and RPMI 1640 (pH 4.5) buffered in citrate. Adjustment in the pH of MOPS-buffered RPMI 1640 reduced trailing in multiple strains of Candida albicans without affecting the MICs for isolates having known susceptible (low-low) and resistant (high-high) phenotypes. Adjustment of the medium pH could be considered to eliminate trailing in azole drug susceptibility testing.

Antifungal Agents↗
PubMed1999

Microdilution susceptibility testing of amphotericin B, itraconazole, and voriconazole against clinical isolates of Aspergillus and Fusarium species.

We compared the activities of amphotericin B, itraconazole, and voriconazole against clinical Aspergillus (n = 82) and Fusarium (n = 22) isolates by a microdilution method adopted from the National Committee for Clinical Laboratory Standards (NCCLS-M27A). RPMI 1640 (RPMI), RPMI 1640 supplemented to 2% glucose (RPMI-2), and antibiotic medium 3 supplemented to 2% glucose (AM3) were used as test media. MICs were determined after 24, 48, and 72 h. A narrow range of amphotericin B MICs was observed for Aspergillus isolates, with minor variations among species. MICs for Fusarium isolates were higher than those for Aspergillus isolates. MICs of itraconazole were prominently high for two previously defined itraconazole-resistant Aspergillus fumigatus isolates and Fusarium solani. Voriconazole showed good in vitro activity against itraconazole-resistant isolates, but the MICs of voriconazole for F. solani were high. RPMI was the most efficient medium for detection of itraconazole-resistant isolates, followed by RPMI-2. While the significance remains unclear, AM3 lowered the MICs, particularly those of amphotericin B.

Amphotericin B↗
PubMed1999

Disk diffusion method for determining susceptibilities of Candida spp. to MK-0991.

We have developed an agar-based methodology for testing susceptibilities of Candida spp. to the new antifungal agent MK-0991, a glucan synthase inhibitor. Results obtained with this method correlated well with the results obtained by the National Committee for Clinical Laboratory Standards M27-A broth microdilution reference method. However, as noted with prior comparisons of broth- and agar-based systems, some isolates yielded inhibition zones which were not consistent with the MICs obtained for them. Understanding the implications of these differences will require testing in an in vivo system.

Anti-Bacterial Agents↗
PubMed1999

Optimizing voriconazole susceptibility testing of Candida: effects of incubation time, endpoint rule, species of Candida, and level of fluconazole susceptibility.

Voriconazole is a new triazole antifungal agent that has potent activity against many isolates of Candida, including Candida krusei and Candida glabrata. In this work, we studied the impact of glucose supplementation, incubation time, agitation of the plates prior to reading, endpoint determination rule, visual versus spectrophotometric reading, Candida species, and fluconazole MIC on the MIC of voriconazole for Candida isolates tested by using the microdilution format assay of the National Committee for Clinical Laboratory Standards (NCCLS) M27-A antifungal susceptibility testing methodology. For both voriconazole and fluconazole, a spectrophotometric endpoint of 50% reduction in turbidity relative to the growth control correlated most closely with the NCCLS-defined visual endpoint of "prominent decrease in turbidity." Correlation was generally better after 24 h of incubation than after 48 h. Supplementation of the medium to contain 20 g of glucose/liter did not alter the MIC significantly but did enhance growth and simplify visual readings. All Candida species appeared potentially susceptible to voriconazole, including isolates of C. krusei. For some isolates for which fluconazole MICs were markedly elevated voriconazole MICs were also elevated, but the clinical significance of these observations remains to be determined.

Amphotericin B↗
PubMed1998

Multidimensional flow-cytometric analysis of dendritic cells in peripheral blood of normal donors and cancer patients.

We studied the potential of multidimensional flow cytometry to evaluate the frequency and maturation/activation status of dendritic cells in minimally manipulated peripheral blood mononuclear cell preparations (i.e., only separated on Ficoll-Hypaque) of normal donors and cancer patients. A rare subset of HLA-DR+ leukocytes (less than 1% mononuclear cells) was detected in blood of normal donors that displayed all the features of dendritic cells: these cells had high forward-light-scatter characteristics and coexpressed CD4, CD86 and CD54 surface antigens, but lacked the lineage-associated surface markers of T cells, B cells, monocytes, granulocytes or NK i.e. they were CD3-, CD19-, CD20-, CD14-, CD11b-, CD16-, CD56-). These physical and phenotypic properties were virtually identical to those of immunomagnetically sorted leukocytes characterized as dendritic-cells on the basis of morphology, phenotype and high stimulatory activity in allogeneic mixed-lymphocyte cultures. Using this flow-cytometric approach we observed that the frequency of dendritic cell-like cells in peripheral blood mononuclear cell specimens of cancer patients receiving chemotherapy alone or those recovering from stem cell transplantation was significantly lower than that of normal individuals (mean +/- SE: 0.36 +/- 0.05%, 0.14 +/- 0.06%, and 0.75 +/- 0.04% respectively). Multidimensional flow-cytometric analysis of dendritic cells might represent an important new tool for assessing immunocompetence, and for monitoring the effects of therapeutic regimens on the immune system.

Dendritic Cells↗
PubMed1998

Predictors of adverse outcome in cancer patients with candidemia.

BACKGROUND: Many factors, including severity of illness, neutropenia, intravenous catheter management, and drug therapy may affect the outcome of candidemia in cancer patients. METHODS: The records of all patients at M. D. Anderson Cancer Center who developed one or more positive blood cultures for Candida spp between January 1, 1988, and December 31, 1992, were retrospectively reviewed. Four hundred ninety-one episodes of candidemia were identified, for which 476 had complete medical records, which were reviewed in detail. RESULTS: By 3-month follow-up, 52% of the patients had died. Neutropenia, higher APACHE III score, and visceral dissemination were associated with poor prognosis. Cure rates, adjusted for severity of illness, were similar for fluconazole and amphotericin B treatment. Exchange of central venous catheters was associated with a modest improvement in prognosis. CONCLUSION: Several factors that influence the outcome of candidemia in cancer patients have been identified. These factors may be relevant for the clinical management of cancer patients with candidemia, and for the design of therapeutic trials.

Adult↗