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Biomedical subjects

M G Rinaldi

Publications and source records attributed to M G Rinaldi.

At least 91 records · Page 5Linked to original sources

Fluconazole disk diffusion susceptibility testing of Candida species.

We describe a simple procedure for detecting fluconazole-resistant yeasts by a disk diffusion method. Forty clinical Candida sp. isolates were tested on RPMI-glucose agar with either 25- or 50-microgram fluconazole disks. With 25-microgram disks, zones of inhibition of >/=20 mm at 24 h accurately identified 29 of 29 isolates for which MICs were </=8 microgram/ml, and with 50-microgram disks, zones of >/=27 mm identified 28 of 29 such isolates. All 11 isolates for which MICs were >8 microgram/ml were identified by using either disk. Disk diffusion may be a useful screening method for clinical microbiology laboratories.

AIDS-Related Opportunistic Infections↗

Disseminated aspergillosis caused by Aspergillus ustus in a patient following allogeneic peripheral stem cell transplantation.

The first case of disseminated aspergillosis caused by Aspergillus ustus in an allogeneic peripheral stem cell transplant patient is described. The patient, a 46-year-old female with a history of myelodysplastic syndrome, underwent high-dose chemotherapy and total body irradiation prior to transplantation. She was released from the hospital 49 days posttransplant (p.t.) in a stable condition with an absolute neutrophil count (ANC) of 2,700 cells per microl. Multiple antimicrobial agents, including itraconazole (ITR), were prescribed during hospitalization and at the time of discharge. Three days after discharge, the patient was readmitted with hemorrhagic cystitis, persistent thrombocytopenia, and bilateral pulmonary consolidation, although no fever was present. The ANC at the time of readmission was 3,500. Upon detection of a pulmonary nodule (day 67 p.t.), a bronchoalveolar lavage was performed; the lavage fluid was positive for both cytomegalovirus and parainfluenza virus and negative for fungus. The patient was placed on ganciclovir. A biopsy specimen from a leg lesion also noted on day 67 p.t. revealed septate hyphae consistent with Aspergillus species, and a culture subsequently yielded Aspergillus ustus. Confirmation detection of A. ustus was made by demonstration of characteristic reproductive structures with the presence of Hülle cells. On day 67 p.t., ITR was discontinued and liposomal amphotericin B (AMB) was initiated. The patient's condition worsened, and she died 79 days p.t. At the time of autopsy, septate hyphae were present in heart, thyroid, and lung tissues, with lung tissue culture positive for A. ustus. In vitro susceptibility testing indicated probable resistance to AMB but not to ITR. This case supports the need for the development of rapid methods to determine antifungal susceptibility.

Aspergillosis↗

U.S. case report of cerebral phaeohyphomycosis caused by Ramichloridium obovoideum (R. mackenziei): criteria for identification, therapy, and review of other known dematiaceous neurotropic taxa.

We report a case of cerebral phaeohyphomycosis in a 36-year-old male caused by the neurotropic fungus Ramichloridium obovoideum (Matushima) de Hoog 1977 (Ramichloridium mackenziei Campbell et Al-Hedaithy 1993). This man resided in the Middle East, where the fungus appears to be endemic and, possibly, geographically restricted, since all previous reports of brain abscesses due to this organism have been for patients indigenous to this area. As a servant of the Saudi Arabian royal family, he appeared in the United States seeking treatment for chronic weight loss, fatigue, decreased memory, and a more recent 2-week history of right-hand weakness which worsened to involve the entire right upper extremity. On the day prior to his admission, he had a focal motor seizure with rotation of the head and eyes to the right, followed by secondary generalization. A computerized tomogram showed a ring-enhancing hypodense lesion in the left parietal subcortical region with associated edema and mass effect. Diagnosis of a fungal etiology was made following a parietal craniotomy and excisional biopsy by observation of septate, dematiaceous hyphal elements 2 to 3 microm in width on hematoxylin-and-eosin-stained sections from within areas of inflammation and necrosis. Culture of the excised material grew out a dematiaceous mould which was subsequently identified as R. obovoideum. At two months postsurgery and with a regimen of 200 mg of itraconazole twice a day, the patient was doing well and returned to Saudi Arabia. His condition subsequently deteriorated, however, and following a 7-month course of itraconzole, he expired. We use this case to alert clinicians and personnel in clinical mycology laboratories of the pathogenicity of this organism and its potential occurrence in patients with central nervous system signs and symptoms who have resided in the Middle East and to review and/or compare R. obovoideum with other neurotropic, dematiaceous taxa and similar nonneurotropic, dematiaceous species.

Adult↗

Comparative evaluation of National Committee for Clinical Laboratory Standards broth macrodilution and agar dilution screening methods for testing fluconazole susceptibility of Cryptococcus neoformans.

A simple screening method for fluconazole susceptibility of Cryptococcus neoformans using 2% dextrose Sabouraud dextrose agar (SabDex) with fluconazole was compared to the National Committee for Clinical Laboratory Standards (NCCLS) broth macrodilution method. By this method, fluconazole-susceptible C. neoformans isolates are significantly smaller on medium with fluconazole than on fluconazole-free medium. Isolates with decreased susceptibility have normal-size colonies on medium containing fluconazole. The 48-h NCCLS broth macrodilution MICs (NCCLS MICs) for isolates with normal-size colonies on 8- or 16-microg/ml fluconazole plates were predicted to be > or =8 or > or =16 microg/ml, respectively. On medium with 16 microg of fluconazole per ml, all strains (84 of 84) for which the NCCLS MICs were <16 microg/ml were correctly predicted, as were all isolates (7 of 7) for which the MICs were > or =16 microg/ml. Agar dilution appears to be an effective screening method for fluconazole resistance in C. neoformans.

Antifungal Agents↗

Fatal Hormonema dematioides peritonitis in a patient on continuous ambulatory peritoneal dialysis: criteria for organism identification and review of other known fungal etiologic agents.

We report a fatal case a fungal peritonitis caused by the yeast-like dematiaceous mould Hormonema dematioides in a 45-year-old woman. The woman had a 13-year history of insulin-dependent diabetes mellitus and had been on continuous ambulatory peritoneal dialysis for chronic renal failure. H. dematioides was repeatedly isolated from the dialysate culture specimens collected on days 3, 9, 16, and 20 of her hospital stay. Preliminary culture reports on day 7 of the growth of a yeast-like fungus, a probable Candida species, prompted the administration of fluconazole (FLU). Intraperitoneal and intravenous FLU failed to eliminate the mould, and the patient expired on day 21 of her hospital stay. We use this case to present what appears to be the first report of fungal peritonitis due to H. dematioides, to provide laboratorians with criteria for differentiating this organism from the similar mould Aureobasidium pullulans and from various yeast genera, and to provide a review of known fungal taxa inciting peritonitis.

Ascitic Fluid↗

Bronchoscopic and serologic diagnosis of Aspergillus fumigatus pulmonary infection in a bottlenose dolphin (Tursiops truncatus).

A 4-yr-old male bottlenose dolphin (Tursiops truncatus) developed an Aspergillus fumigatus pneumonia. Fungal elements were identified by cytology and microbiology from endoscopic bronchoalveolar lavage and brushings of a raised yellow endobronchial lesion. The results of qualitative immunodiffusion serology, a technique that identifies specific circulating antibodies to Aspergillus fumigatus, were suggestive of an active infection. The dolphin was treated with itraconazole for over 2 yr, which resulted in remission of clinical signs. Pneumonia caused by Aspergillus sp. accounts for the large majority of pulmonary mycoses in marine mammals. Bronchoscopy facilitated an early definitive diagnosis, accurate treatment, and remission.

Amoxicillin-Potassium Clavulanate Combination↗

In vitro activity of voriconazole against selected fungi.

Fifty-nine isolates consisting of 14 genera and 33 species of ascomycetes, basidiomycetes, and zygomycetes were tested against amphotericin B, fluconazole, itraconazole and voriconazole using an in vitro modified macrobroth dilution procedure based upon the NCCLS M27-A standard method for yeasts. The triazoles voriconazole and itraconazole had similar MIC values, except for Acremonium alabamensis, A. strictum, Fusarium oxysporum, F. solani and Wangiella dermatitidis, which had substantially lower voriconazole MIC values. Voriconazole MIC values were lower than those for itraconazole for the 17 species of Trichosporon tested. Fluconazole had high MIC values, often greater than 128 microg ml-1.

Amphotericin B↗

Importance of Candida species other than Candida albicans as opportunistic pathogens.

Candida species other than C. albicans have become a significant cause of infection in humans. Several of the more commonly isolated of these species are less susceptible to commonly used azole antifungal drugs, a factor that poses significant difficulties for effective treatment. The modern mycology laboratory has an important role to play in several aspects relating to these organisms, including therapy, detection, identification and epidemiological analysis. The application of molecular techniques and phylogenetic analysis has led to the identification of a new species of Candida associated with mucosal candidiasis in HIV-infected individuals named Candida dubliniensis, the clinical significance of which is currently under investigation. Molecular techniques are also being applied to the analysis of determinants involved in pathogenicity of species such as Candida glabratta. These approaches should lead to a better understanding of these organisms and there ability to cause disease and should also provide more effective treatment.

AIDS-Related Opportunistic Infections↗

Development of interpretive breakpoints for antifungal susceptibility testing: conceptual framework and analysis of in vitro-in vivo correlation data for fluconazole, itraconazole, and candida infections. Subcommittee on Antifungal Susceptibility Testing of the National Committee for Clinical Laboratory Standards.

The availability of reproducible antifungal susceptibility testing methods now permits analysis of data correlating susceptibility in vitro with outcome in vivo in order to define interpretive breakpoints. In this paper, we have examined the conceptual framework underlying interpretation of antimicrobial susceptibility testing results and then used these ideas to drive analysis of data packages developed by the respective manufacturers that correlate fluconazole and itraconazole MICs with outcome of candidal infections. Tentative fluconazole interpretive breakpoints for MICs determined by the National Committee for Clinical Laboratory Standards' M27-T broth macrodilution methodology are proposed: isolates for which MICs are < or = 8 microg/mL are susceptible to fluconazole, whereas those for which MICs are > or = 64 microg/mL appear resistant. Isolates for which the MIC of fluconazole is 16-32 microg/mL are considered susceptible dependent upon dose (S-DD), on the basis of data indicating clinical response when > 100 mg of fluconazole per day is given. These breakpoints do not, however, apply to Candida krusei, as it is considered inherently resistant to fluconazole. Tentative interpretive MIC breakpoints for itraconazole apply only to mucosal candidal infections and are as follows: susceptible, < or = 0.125 microg/mL; S-DD, 0.25-0.5 microg/mL; and resistant, > or = 1.0 microg/mL. These tentative breakpoints are now open for public commentary.

Animals↗

Antifungal susceptibility testing: technical advances and potential clinical applications.

The clinical application of in vitro antifungal susceptibility testing has been limited by a lack of reproducibility and uncertain clinical relevance. As a result of several collaborative studies, the National Committee for Clinical Laboratory Standards (NCCLS) has proposed a standardized antifungal susceptibility test method, NCCLS M27-T. More convenient, user-friendly methods (microdilution broth and stable gradient technology) have been evaluated, and the potential for a similar process with a disk diffusion method is apparent. Adaptation of the standard method for susceptibility testing of filamentous fungi appears promising. The existence of a standardized method facilitates meaningful analysis of studies addressing the issue of clinical relevance of antifungal susceptibility testing. Correlation of MICs with clinical response to therapy is beginning to emerge, most notably in relation to fluconazole and itraconazole therapy for oropharyngeal candidiasis associated with infection with the human immunodeficiency virus. This accumulated experience with antifungal susceptibility testing allows us to provide several specific recommendations for antifungal susceptibility testing in the clinical laboratory. Application of this developing technology to new antifungal agents and other disease states will enhance our ability to effectively deal with the emerging problem of fungal infection.

Antifungal Agents↗

Stable azole drug resistance associated with a substrain of Candida albicans from an HIV-infected patient.

Oral candidiasis is one of the earliest and most frequent complications of a failing immune system in HIV-infected individuals. For several years, oral candidiasis has been treated effectively with azole drugs, the one most frequently used is fluconazole. Unfortunately, extensive use of the drug for treatment and prophylaxis has led to treatment failure in an increasing number of patients. In most of these cases, strains of C. albicans isolated from the infection are less susceptible to fluconazole. The development of azole resistance in strains of C. albicans has been studied biochemically and more recently with molecular techniques. One excellent example of the development of azole resistance in C. albicans has been documented in a series of 17 C. albicans isolates from a single patient over a 2-year period. During this time, the patient experienced 14 episodes of oral candidiasis and was treated with increasing doses of fluconazole. Molecular and biochemical analyses confirms that the isolates are the same strain of C. albicans and that the resistance in these isolates is stable over 600 generations, suggesting that the changes in this strain are genetic in nature. In addition, the development of resistance is correlated with the identification of a substrain or variant of the original strain, as identified by restriction fragment length polymorphism (RFLP) analysis with the moderately repetitive probe, Ca3. The analysis of this series of isolates demonstrates that azole drug resistance is associated with several small genetic changes, each of which contributes to the overall resistance of the strain. Clearly, continual use of azole drugs by a patient can select for genetic changes that render oral candidiasis refractory to treatment.

AIDS-Related Opportunistic Infections↗

Fluconazole tolerance in clinical isolates of Cryptococcus neoformans.

Eleven isolates of Cryptococcus neoformans were investigated to determine the biochemical basis of their tolerance to fluconazole. The MICs of fluconazole for three isolates with low-level resistance were 3- to 6-fold higher than those for sensitive isolates, while the MICs for four isolates with high-level resistance were 100- to 200-fold higher than those for sensitive isolates. The level of ergosterol present in the isolates varied, and those which had relatively low levels of ergosterol were resistant to amphotericin B. Changes in the affinity of the target enzyme (sterol 14alpha-demethylase) and decreases in the cellular content of fluconazole seemed to be responsible for the resistance in isolates with low-level and high-level resistance, respectively.

Amphotericin B↗

In vitro evaluation of voriconazole against some clinically important fungi.

Voriconazole was compared to amphotericin B, fluconazole, and itraconazole by using an in vitro macrobroth dilution test based upon current National Committee for Clinical Laboratory Standards tentative standards against the dimorphic fungi and several opportunistic molds and yeasts. In all instances, the voriconazole MICs were lower than those of fluconazole. In most instances, the MICs were lower than the recorded MICs of amphotericin B and itraconazole.

Antifungal Agents↗

Nystatin prophylaxis.

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Administration, Cutaneous↗

Multicenter evaluation of proposed standardized procedure for antifungal susceptibility testing of filamentous fungi.

A multicenter study was conducted to expand the generation and analysis of data that supports the proposal of a reference method for the antifungal susceptibility testing of filamentous fungi. Broth microdilution MICs of amphotericin B and itraconazole were determined in 11 centers against 30 coded duplicate pairs of Aspergillus spp., Fusarium spp., Pseudallescheria boydii, and Rhizopus arrhizus. The effect of inoculum density (approximately 10(3) and 10(4) CFU/ml), incubation time (24, 48, and 72 h), and procedure of MIC determination (conventional and colorimetric [Alamar Blue] evaluation of growth inhibition) on intra- and interlaboratory agreement was analyzed. Based on intra- (97 to 100%) and interlaboratory (94 to 95%) agreement for both drugs, the overall optimal testing conditions identified were determination of colorimetric MICs after 48 to 72 h of incubation with an inoculum density of approximately 10(4) CFU/ml. These testing conditions are proposed as guidelines for a reference broth microdilution method.

Antifungal Agents↗

Candida and Torulopsis: a blinded evaluation of use of pseudohypha formation as basis for identification of medically important yeasts.

Seventy yeast isolates representing species in the genera Candida and Torulopsis but excluding Candida albicans were examined in three laboratories for production of pseudohyphae in Dalmau cultures. The microscopic morphology of the isolates was scrutinized by four individuals experienced in yeast identification and three inexperienced persons, all of whom were blinded as to the putative identification of the yeasts. For 49 (70%) of the 70 isolates, the seven observers recorded comparable scores for morphology, but 5 (7%) of the isolates showed extreme variation in recorded morphologies, from true hyphae formed to no pseudohyphae formed. Isolates of Candida parapsilosis and Torulopsis glabrata consistently did and did not form pseudohyphae, respectively: however, other Candida and Torulopsis spp. did not always express their expected morphologies. In 48 (19%) of 252 readings (seven observers), 36 isolates of Candida spp. were scored as forming no pseudohyphae, and in 22 (9.2%) of 238 readings, 34 isolates of Torulopsis spp. were recorded as forming true hyphae or pseudohyphae. These results show that pseudohypha formation is not a reliable characteristic for identification of yeasts at the genus level; we suggest that the merger of Torulopsis spp. into the genus Candida should be finally accepted.

Candida↗

Invasive Nattrassia mangiferae infections: case report, literature review, and therapeutic and taxonomic appraisal.

We report on a case of subcutaneous infection of the arm caused by the coelomycetous fungus Nattrassia mangiferae (formerly Hendersonula toruloidea) in a steroid-dependent diabetic man with chronic obstructive lung disease. The man was a resident of Arizona, where the fungus is known to be endemic on Eucalyptus camaldulensis and on citrus trees. Diagnosis of fungal infection was made by observation of narrow hyphal filaments by histopathology of biopsy specimens and isolation of a fast-growing black mold which demonstrated hyphae and arthroconidia of varying widths typical of the Scytalidium synanamorph (S. dimidiatum). The formation of pycnidia, which at maturity expressed conidia with a central median dark band, allowed for the confirmation of the isolate as N. mangiferae. Remission of the lesions occurred following intravenous therapy with amphotericin B, followed by topical clotrimazole treatment. We use this patient's case report as an opportunity to review the literature on cases of deep infection caused by Scytalidium species, to evaluate the antifungal susceptibilities of a spectrum of Scytalidium isolates, and to review the taxonomy of Scytalidium species isolated from human infections.

Aged↗