New spectrum of fungal infections in patients with cancer

Saccharomyces cerevisiae infections and antifungal susceptibility studies by colorimetric and broth macrodilution methods

Saccharomyces cerevisiae was isolated in large numbers from operative specimens from two patients with perforated bowel and peritonitis and from the blood of another patient treated with extracorporeal membrane oxygenation. Susceptibility studies were performed on these three isolates and another 29 isolates that colonized or caused infection in a total of 19 patients seen over the last decade. All isolates had low minimum inhibitory concentration (MIC) values for amphotericin B (MIC90 of < or = 0.02 microgram/ml) and flucytosine (MIC90 of 0.2 microgram/ml), and a broader range of MIC values for itraconazole (MIC90 of 0.8 microgram/ml) and fluconazole (MIC90 of 4 micrograms/ml). A colorimetric method using Alamar blue reagent showed good concordance with the standard broth macrodilution method for amphotericin B, flucytosine, and fluconazole, but less good concordance for itraconazole. Serious infections with S. cerevisiae probably should be treated with amphotericin B, with or without the addition of flucytosine.

New and emerging yeast pathogens

The most common yeast species that act as agents of human disease are Candida albicans, Candida tropicalis, Candida glabrata, Candida parapsilosis, and Cryptococcus neoformans. The incidence of infections by other yeasts has increased during the past decade. The most evident emerging pathogens are Malassezia furfur, Trichosporon beigelii, Rhodotorula species, Hansenula anomala, Candida lusitaniae, and Candida krusei. Organisms once considered environmental contaminants or only industrially important, such as Candida utilis and Candida lipolytica, have now been implicated as agents of fungemia, onychomycosis, and systemic disease. The unusual yeasts primarily infect immunocompromised patients, newborns, and the elderly. The role of central venous catheter removal and antifungal therapy in patient management is controversial. The antibiograms of the unusual yeasts range from resistant to the most recent azoles and amphotericin B to highly susceptible to all antifungal agents. Current routine methods for yeast identification may be insufficient to identify the unusual yeasts within 2 days after isolation. The recognition of unusual yeasts as agents of sometimes life-threatening infection and their unpredictable antifungal susceptibilities increase the burden on the clinical mycology laboratory to pursue complete species identification and MIC determinations. Given the current and evolving medical practices for management of seriously ill patients, further evaluations of the clinically important data about these yeasts are needed.

Ecthyma gangrenosum-like lesions: a sign of disseminated Fusarium infection in the neutropenic patient

Fusarium is a saprophytic fungus of soil causing disease in plants and animals. In the immunocompetent patient, Fusarium is non-invasive, colonizing wounds, ulcers or nails. In the immunocompromised host, however, especially in those whose neutrophil and macrophage function is deficient, it can cause devastating systemic infections. Skin lesions are an early feature of the disseminated disease. Rapid diagnosis and treatment are mandatory in order to give the patient a better chance of survival, reported mortality rates being as high as 90%.

Rapid detection and identification of pathogenic fungi by polymerase chain reaction amplification of large subunit ribosomal DNA

We describe a polymerase chain reaction (PCR) based approach to the detection and identification of pathogenic fungi which has potential for the diagnosis of systemic mycoses. Primers to sequences of the large subunit ribosomal DNA genes, which are universally conserved within the fungal kingdom, were capable of amplifying DNA from 43 strains representing 20 species (12 genera) of medically important fungi. Sequence analysis of the products obtained from Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans allowed us to design species-specific primers which only amplified homologous DNA. The use of these two PCRs in tandem allows the detection (universal PCR) and identification (species-specific PCR) of a fungal pathogen within 8 h from simulated clinical specimens.

Successful treatment of catheter-related fusarial infection in immunocompromised children

Fusarium infection is increasingly reported in immunocompromised patients. The role of central venous catheters as potential portals of entry for Fusarium is possibly underestimated. Four cases of catheter-related fusarial infection in children with acute leukemia or a solid tumor are described. These patients had an excellent response to removal of the central venous catheter and treatment with amphotericin B.

Central venous catheter infection with Rhodotorula minuta in a patient with AIDS taking suppressive doses of fluconazole

A case of Rhodotorula minuta central venous catheter infection with fungaemia is described in a patient with advanced acquired immunodeficiency syndrome (AIDS), HIV nephropathy, end-stage renal disease requiring haemodialysis, and a permanent Quinton catheter in place for 6 months. At the time of fungaemia, the patient was taking 100 mg fluconazole per os daily for a previous episode of Candida oesophagitis. R. minuta central venous catheter infection with fungaemia was successfully treated with 455 mg total dose amphotericin B (0.6 mg kg-1 day-1) over 25 days without removal of the catheter. In vitro antifungal susceptibility testing for R. minuta revealed a minimum inhibitory concentration to fluconazole of > 100 micrograms ml-1 and to amphotericin B of 1.2 microgram ml-1. Clinically evident fungaemia, even with an unusual organism such as R. minuta, may occur in patients with intravenous catheters, and while the immunosuppressed patient is receiving azole therapy.

Mycetoma due to Exophiala jeanselmei and Mycobacterium chelonae in a 73-year-old man with idiopathic CD4+ T lymphocytopenia

Exophiala jeanselmei and Mycobacterium chelonae were isolated from cutaneous nodules in a 73-year-old man with mycetoma of the right lower leg. Further evaluation revealed CD4+ lymphocytopenia without evidence of HIV infection. Antibodies to HIV 1/2, p24 antigen and HIV 1/2 (PCR) and reverse transcriptase activity were not detectable. The patient was not a member of any HIV risk group. He had not previously undergone therapy or suffered from immunodeficiency. This case clearly demonstrates that infections with opportunistic moulds and/or atypical mycobacteria should be taken into consideration not only in patients with classical immundeficiency diseases but also in apparently healthy patients because infection with these agents can be the first sign of underlying immunodeficiency.

Mixed intranasal infection caused by Fusarium solani and a zygomycete in a leukaemic patient

We report a case of mixed intranasal infection caused by Fusarium solani and a zygomycete, with probable sinus and brain involvement. The patient had chronic myelogenous leukaemia and was treated with chemotherapy. Diagnosis of the infection was established by direct examination of the intranasal eschar and histopathological study of an excisional biopsy. Only F. solani was isolated from both specimens. Difficulties in diagnosis and treatment of these infections are discussed.

Activities of amphotericin B and antifungal azoles alone and in combination against Pseudallescheria boydii

In order to develop new approaches to treatment of infections due to Pseudallescheria boydii, the in vitro antifungal activity of amphotericin B alone and in combination with miconazole, itraconazole, and fluconazole was studied. Combinations of amphotericin B and antifungal azoles were synergistic, additive, or indifferent in their interaction against P. boydii. Antagonism was not observed.

Effect of increasing inoculum sizes of pathogenic filamentous fungi on MICs of antifungal agents by broth microdilution method

Inoculum size is a critical variable in development of methods for antifungal susceptibility testing for filamentous fungi. In order to investigate the influence of different inoculum sizes on MICs of amphotericin B, 5-fluorocytosine, itraconazole, and miconazole, 32 clinical isolates (8 Aspergillus fumigatus, 8 Aspergillus flavus, 5 Rhizopus arrhizus, 8 Pseudallescheria boydii, and 3 Fusarium solani isolates) were studied by the broth microdilution method. Four inoculum sizes were studied: 1 x 10(2) to 5 x 10(2), 1 x 10(3) to 5 x 10(3), 1 x 10(4) to 5 x 10(4), and 1 x 10(5) to 5 x 10(5) CFU/ml. The National Committee for Clinical Laboratory Standards reference method for antifungal susceptibility testing in yeasts was modified and applied to filamentous fungi. The inoculum was spectrophotometrically adjusted, and all tests were performed in buffered medium (RPMI 1640) at pH 7.0 with incubation at 35 degrees C for 72 h. MICs were read at 24, 48, and 72 h. Amphotericin B showed a minimum effect of inoculum size on MICs for all species with the exception of P. boydii (P < 0.05). A significant effect of inoculum size on MICs was observed with 5-fluorocytosine, for which there was an increase of more than 10-fold in MICs against all Aspergillus spp. between inoculum concentrations of 10(2) and 10(4) CFU/ml (P < 0.001). For itraconazole, the results showed a more species-dependent increase of MICs, most strikingly for R. arrhizus and P. boydii. Miconazole, which was tested only with P. boydii, did not demonstrate a significant effect of inoculum size on MICs. In summary, the effect of inoculum size on MICs for filamentous fungi was dependent upon the organism and antifungal compound tested. Thus, among antifungal compounds, itraconazole and 5-fluorocytosine demonstrated significant inoculum effects, while amphotericin B and miconazole showed comparatively minimum inoculum effects against pathogenic filamentous fungi. Moreover, among filamentous fungi, P. boydii and R. arrhizus exhibited the greatest inoculum effect.

Successful treatment of a brain abscess due to Trichoderma longibrachiatum after surgical resection

A case of brain abscess due to Trichoderma longibrachiatum in a leukemic patient with prolonged neutropenia is reported. Definitive cure was achieved after neurosurgical resection of the abscess and prolonged antifungal therapy. Trichoderma is a filamentous fungus species, which is only exceptionally pathogenic in humans. This genus and particularly the species Trichoderma longibrachiatum should be added to the growing list of fungi causing infection in immunocompromised patients.

In vitro evaluation of the pneumocandin antifungal agent L-733560, a new water-soluble hybrid of L-705589 and L-731373

Lipopeptide L-733560 is a hybrid analog of L-731373 and L-705589. All are water-soluble semisynthetic pneumocandin Bo derivatives. In vitro susceptibility testing of L-705589, L-731373, and L-733560 against more than 200 clinical isolates consisting of eight Candida species, Cryptococcus neoformans, and three Aspergillus species was performed by the broth microdilution methods. All three pneumocandins exhibited potent anti-Candida activity and moderate anti-C. neoformans activity. However, anti-Aspergillus activity was demonstrated only by an agar disk diffusion method. Antifungal agent-resistant Candida species and C. neoformans showed susceptibility comparable to that of susceptible isolates. Growth inhibition kinetic studies against Candida albicans revealed fungicidal activity within 3 to 5 h. Drug combination studies with pneumocandins and amphotericin B revealed indifferent activity against C. albicans and additive effects against C. neoformans and Aspergillus fumigatus. The activities of the compounds were not dramatically affected by the presence of serum. Resistance induction studies showed that the susceptibility of C. albicans MY1055 was not significantly altered by repeated exposure to subinhibitory concentrations of L-733560. Erythrocyte hemolysis studies indicated minimal hemolytic potential with pneumocandins. Results from preclinical evaluations and development studies performed thus far indicate that the pneumocandins should be safe, broad-spectrum fungicidal agents and potent parenteral antifungal agents.

Prostatic aspergillosis

Prostatic aspergillosis is rare with only 3 cases reported previously. We report a case of localized invasive aspergillosis of the prostate in a nonimmunocompromised patient with chronic urinary retention and recurrent urinary tract infections. Transurethral resection followed by open prostatectomy was performed for massive prostatomegaly. No systemic antifungal therapy was required for cure. The literature is reviewed, and diagnostic and management options are discussed.

Activities of D0870, a novel triazole, against Candida lusitaniae and Trichosporon beigelii in experimental murine infections

Candida lusitaniae and Trichosporon beigelii may cause life-threatening infections in the immunocompromised host and may be resistant to amphotericin B. We assessed the activities of a new triazole, D0870, against one T. beigelii and four C. lusitaniae strains, in comparison with those of fluconazole and amphotericin B. Immunosuppressed CF1 mice, intravenously infected with each fungal strain, received 3 days of therapy with oral D0870 (5 or 25 mg/kg of body weight daily), fluconazole (5 to 50 mg/kg daily), or parenteral amphotericin B (1 or 2 mg/kg daily). Survival was significantly prolonged and kidney fungus titers were reduced in mice treated with D0870 compared with untreated mice (P < or = 0.05). Treatment with D0870 was significantly more effective than that with amphotericin B or fluconazole in animals infected with two of the C. lusitaniae strains and equally effective for the remaining two C. lusitaniae strains and the T. beigelii strain. Fluconazole and amphotericin B failed to improve the survival of mice infected with one and two C. lusitaniae strains, respectively. D0870 was active against all the organisms tested, including those resistant to fluconazole and amphotericin B.

New and unusual infections in neutropenic patients

Infections in immunocompromised patients with cancer are common and the primary risk factor is neutropenia, usually induced by chemotherapeutic agents. The spectrum of bacterial infection is shifting from gram-negative to gram-positive. The array of fungal infections in cancer patients is expanding to include organisms previously unknown as invasive human pathogens. New species are being defined to explain extant pathologies, and free living algae are now emerging as pathogens in immunocompromised patients. Physicians must remain alert to these emerging pathogens and to the need to evaluate optimal treatments for the usual and unusual infections in neutropenic and other compromised patients with cancer and allied diseases.

Comparative efficacies of amphotericin B, triazoles, and combination of both as experimental therapy for murine trichosporonosis

We assessed the activities of amphotericin B deoxycholate, liposomal amphotericin B, fluconazole, and SCH 39304 against 10 strains of Trichosporon beigelii in mice with hematogenous infections. Cyclophosphamide-immunosuppressed CF1 male mice were challenged intravenously with a lethal inoculum of T. beigelii (5 x 10(6) conidia per mouse) and were assigned to different treatment groups or were left untreated. Amphotericin B deoxycholate (1 mg/kg of body weight and liposomal amphotericin B (1, 5, and 10 mg/kg) were given parenterally once daily. Escalating doses (5, 10, and 20 mg/kg/day) of fluconazole and SCH 39304 were tested. We also compared the activity of amphotericin B deoxycholate plus fluconazole (1 and 10 mg/kg/day, respectively) with that of each agent alone. Fluconazole significantly prolonged the survival of mice infected with each of the 10 strains tested. Amphotericin B deoxycholate achieved various responses, improving the outcomes in mice infected with seven of the strains. Liposomal amphotericin B was not more effective than amphotericin B deoxycholate against the two strains tested. Both fluconazole and SCH 39304 reduced the kidney fungal counts in a dose-dependent pattern, with SCH 39304 being more active than fluconazole against one of the two strains tested. The activity of the combination of amphotericin B deoxycholate plus fluconazole appeared to be superior to that of either agent alone, especially in reducing the kidney fungal burden. Fluconazole is more active than amphotericin B deoxycholate against experimental murine trichosporonosis.

Successful treatment of a Trichosporon beigelii septicemia in a granulocytopenic patient with amphotericin B and granulocyte colony-stimulating factor

Invasive fungal infections have become an increasing problem in severely immunocompromised hosts. We here report a case of septicemia, caused by Trichosporon beigelii, an unusual pathogen of systemic infections. This infection was acquired during a period of severe neutropenia after chemotherapy for relapsed acute myelogenous leukemia following allogeneic bone marrow transplantation. The patient recovered from a life-threatening T. beigelii septicemia due to early intensified treatment with amphotericin B and a rapid neutrophil recovery, enhanced by granulocyte colony-stimulating factor (G-CSF). According to the current literature, amphotericin B is the treatment of choice for systemic T. beigelii infections. In patients with severe granulocytopenia, the rapid recovery of neutrophils remains the most important factor for the outcome of this infection.

A fatal infection with Alternaria alternata and Aspergillus terreus in a child with agranulocytosis of unknown origin

Alternaria alternata and Aspergillus terreus were isolated from cutaneous nodules in a 5-year-old girl with agranulocytosis of unknown origin. Histopathological examination supported the diagnosis of an infection with two opportunistic moulds. Aspergillus terreus was also isolated from the secretions of the maxillary sinuses of the patient. In spite of antimycotic therapy, the child eventually died from respiratory failure.

Non-Candida fungal infections after bone marrow transplantation: risk factors and outcome

PURPOSE

To determine the incidence, risk factors, and outcome of non-Candida fungal infections in a bone marrow transplant population.

PATIENTS AND METHODS

A consecutive series of 1,186 patients who underwent bone marrow transplant at the University of Minnesota Hospital between 1974 and 1989 were analyzed for the occurrence of a post-transplant non-Candida fungal infection. The risk factors were analyzed with regard to clinical characteristics such as age, sex, primary disease process, type of transplant, recipient cytomegalovirus serostatus, time to engraftment, and the presence of graft-versus-host disease.

RESULTS

In this population, 123 of 1,186 patients (10%) developed a non-Candida fungal infection within 180 days of transplant. The majority of infections (85%) occurred in allogeneic recipients, and 58% of infections were prior to white blood cell engraftment. The most common isolates were Aspergillus species (70%), Fusarium species (8%), and Alternaria species (5%). Although 47% of infections involved a single organ or site, 44% were disseminated and 9% were isolated fungemias. Only 17% of patients survived. Sixty-eight percent of deaths were related to the fungal infection. In univariate analysis, allogeneic transplant, positive recipient cytomegalovirus serostatus, delayed engraftment, and recipient age of greater than or equal to 18 years were identified as risk factors for non-Candida fungal infection. All of these factors except for recipient age were independently significant in multivariate analysis. In allogeneic recipients, positive cytomegalovirus serostatus, delayed engraftment, and age of greater than or equal to 18 years were each significantly associated with a greater risk of fungal infection; none of these factors were independently significant in the autologous recipients.

CONCLUSION

Fungal infections remain a major cause of morbidity and mortality in patients undergoing bone marrow transplant. More effective antifungal prophylaxis and therapy, earlier diagnosis, and transplant regimens incurring a brief period of neutropenia may substantially reduce the incidence and clinical impact of these infections.

Clinical patterns of Fusarium infections in immunocompromised patients

Fusarium is an ubiquitous fungus commonly found in soil and on plants. Human infection usually occurs as a result of inoculation of the organism through the body surface, thus causing skin infection, onychomycosis, keratitis, endophthalmitis and arthritis. Dissemination may occur in subjects with underlying immunodeficiency. Among immunocompromised hosts, Fusarium sp. is an emerging pathogen in neutropenic patients. To our knowledge, since 1973, when the first disseminated fusariosis in a child with acute leukemia was reported, about 80 new cases have been reported, mainly occurring in patients with haematologic malignancies. Specific portals of entry are not well understood, nevertheless the respiratory tract, colonised gastrointestinal tract, onychomycosis, disrupted skin barrier and central venous catheter have been reported as entry sites of deep seated Fusarium infections. Fever, positive blood cultures, severe myalgias, disseminated ecthyma gangrenosum-like skin lesions, ocular symptoms and multiple-organ-system involvement are distinctive features in most cases of disseminated fusariosis. The prognosis is very poor with death generally following despite antifungal therapy, unless an increase in the white blood cell count occurs. All available antifungal drugs show a low activity against the various species of Fusarium. Nevertheless, amphotericin B seems to have the highest in vitro activity and, even if it does not appear to be effective in persistently neutropenic patients, it should be currently considered to be the treatment of choice.

Disseminated Trichosporon beigelii infection in patients with malignant diseases: immunohistochemical study and review

Trichosporon beigelii is a causative agent of opportunistic infection and summer-type hypersensitivity pneumonitis in Japan. However, as the diagnosis of Trichosporon beigelii infection is sometimes difficult, the actual incidence of this disease may be underestimated. Of 203 autopsy patients with malignant disease, seven (7.7%) were diagnosed with disseminated Trichosporon beigelii infection by immunohistochemical investigation of formalin-fixed, paraffin-embedded tissue sections. Including these seven, a total of 43 patients with Trichosporon beigelii infection have been reported in Japan. The majority of them had underlying hematologic malignancies, for which they received cytotoxic chemotherapy resulting in neutropenia. This study indicates that the immunohistochemical method, which can be applied to biopsy specimens, is an excellent tool for specific diagnosis of Trichosporon beigelii infection, which is an emerging fatal mycosis in immunocompromised patients with profound neutropenia.

Trichosporon on humans: a practical account

Six human pathogenic Trichosporon species are described with respect to criteria for routine identification, epidemiology and clinical origin: T. ovoides, T. inkin, T. asahii, T. asteroides (Fissuricella filamenta), T. cutaneum, and T. mucoides. These species are causative agents of white piedra and cutaneous infections and are involved in systemic, localized or disseminated mycoses, particularly in patients with underlying haematological malignancy. Data on in vitro sensitivity to antifungal drugs are provided.

Fungemia in patients with leukemia

A nine-year retrospective study on fungemia in patients with leukemia was conducted. A total of 79 episodes of fungemia in 77 patients with leukemia were documented. Candida parapsilosis fungemia was associated more frequently with the presence of a central venous line and to the use of parenteral nutrition than the other fungal species (p = 0.00026 and p = 0.01, respectively). The same fungus was isolated from both blood and surveillance cultures in 95% of Candida albicans and in 89% of Candida tropicalis fungemia (p < 0.01 and p = 0.02, respectively). The neutropenia and fungus colonization that resulted was associated significantly with the presence of invasive disease (p = 0.0024 and p = 0.0028, respectively). Conversely, central venous catheterization and parenteral nutrition appeared to be associated with episodes without deep tissue invasion (p = 0.000037 and p = 0.001, respectively). Invasive mycosis due to the fungus isolated from blood was documented in 51 patients with a mortality rate of 69%, whereas in 20 patients without invasive mycosis, mortality rate was 21% (p = 0.000059). In patients with fungemia, related or unrelated to the presence of a central venous catheter, mortality was 24% and 64%, respectively (p = 0.00042). Mortality was highest with C. tropicalis (p = 0.0017) and lowest with C. parapsilosis (p = 0.057). Severe neutropenia (polymorphonuclears < 100/mmc) appeared associated with a higher mortality rate (p = 0.012), whereas the recovery of neutropenia was related adversely to a fatal outcome (p < 0.01). With antifungal therapy, there was no statistically significant difference whether antifungal therapy was given or not.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnosis of invasive mycoses in severely immunosuppressed patients

In compromised patients, invasive mycoses are being observed at an increasing frequency and with a broadening spectrum of causative fungi. The rapid and definitive diagnosis of such opportunistic mycoses requires the synoptical consideration of predisposing clinical conditions, of culture isolates, and of the results of nonculture techniques. At present, the latter comprise the monitoring of specific antibodies and of fungal antigens, and the microscopical examination of suspected biopsies. The validity of the individual techniques (e.g., the monitoring of antibodies or antigens) varies with individual mycoses. Alternative methods for monitoring fungal metabolites or nucleic acids are still in the developmental stage. Particularly the amplification of DNA by the polymerase chain reaction (PCR) has a high diagnostic potential. However, at present, it is uncertain whether PCR allows the necessary distinction between colonization and truly invasive infection, and whether PCR can be simplified sufficiently to allow the continuous surveillance of high-risk patients.

Disseminated Trichosporon beigelii infection causing skin lesions in a renal transplant patient

A 45-year-old renal transplant patient presented with a recent history of small reddish nodular lesions on thighs, back and face. Biopsy of the nodules revealed numerous hyphae. Trichosporon beigelii was isolated from the biopsy specimen. Marked improvement occurred after 2 weeks' treatment with fluconazole, although its MIC was 16 mg/l.

Case report: phaeohyphomycosis due to Curvularia lunata involving skin and subcutaneous tissue after an explosion at a chemical plant

Cases of phaeohyphomycosis due to dematiaceous fungi have been reported in increasing numbers and diversity. The optimal roles of antifungal chemotherapy and surgical debridement in the management of these infections have not been determined. A case of acute cutaneous and subcutaneous phaeohyphomycosis due to Curvularia lunata after an explosion at a chemical plant is reported, in which the organisms may have been inoculated into the tissues by the force of the blast. No organisms were found by histopathologic examination or culture of excisional biopsy specimens taken 10 days after initiation of therapy with intravenous amphotericin B; the antifungal therapy may have eradicated the infection.

Disseminating infection with Scytalidium dimidiatum in a granulocytopenic child

A 13-year-old Moroccan boy in The Netherlands developed fever and a lesion resembling ecthyma gangrenosum on the abdomen during cytostatic drug treatment for a lymphoblastic B-cell lymphoma. Scytalidium dimidiatum was cultured from blood and the abdominal skin lesion. The patient was successfully treated with amphotericin B. The fungus Scytalidium dimidiatum is a fairly common plant pathogen in tropical and subtropical countries and is known to cause dermatomycoses in humans in these areas. This case demonstrates that it is necessary to be aware that immigrants from these areas can import their own fungal flora, some members of which may cause life-threatening disease in the case of patients with immune suppression.

Prospective evaluation of effects of broad-spectrum antibiotics on gastrointestinal yeast colonization of humans

This study evaluated the effects of broad-spectrum antibiotics on the gastrointestinal (G.I.) yeast flora of humans and correlated the findings with those obtained from a mouse model of G.I. colonization by Candida albicans. We prospectively studied 46 adult cancer patients who received one of five broad-spectrum antibiotics (ceftriaxone, ceftazidime, ticarcillin-clavulanic acid, imipenem-cilastatin, and aztreonam) as therapy for infections. Quantitative examination of yeast colonization of stools was conducted at the baseline, at the end of antibiotic treatment, and 1 week after discontinuation of therapy. Antibiotics with anaerobic activity (ticarcillin-clavulanic acid) or high G.I. concentrations (ceftriaxone) caused a higher and more sustained increase in G.I. colonization by yeasts than did antibiotics with poor anaerobic activity (ceftazidime and aztreonam) or a low G.I. concentration (imipenem-cilastatin). These results were similar to those obtained with a mouse model of G.I. colonization by C. albicans that involved the same antibiotics. Hence, the mouse model may be useful for evaluation of yeast colonization of the human G.I. tract.

Three cases of infection with Fusarium species in neutropenic patients

Three cases are reported of disseminated infection due to Fusarium species in severely neutropenic patients. The clinical findings in all patients included fever, painful disseminated nodular skin lesions and severe myalgia. The outcome was fatal despite early administration of amphotericin B. The portal of entry of the organism was probably the nasal sinus in two cases.

Laboratory aids in the diagnosis of invasive candidiasis

The laboratory diagnosis of candidiasis continues to be problematic; however, there have been several advances in the past decade which promise to enhance our ability to identify patients at high risk for infection and/or to document invasive candidiasis in critically ill and immunocompromised patients. The introduction of commercially available biphasic blood culture medium and subsequently the lysis-centrifugation procedure has markedly improved the ability of laboratories to detect fungemia. Although serologic methods have not been very successful in diagnosing candidiasis in immunocompromised patients, several antigen detection methods are now under investigation. In addition, detection of fungal metabolites such as D-arabinitol remains promising. Finally, application of the techniques of molecular biology for typing and detection of fungal pathogens has expanded our understanding of candidal infections and may offer the most sensitive and specific means of diagnosing invasive candidiasis.

A novel murine model of disseminated trichosporonosis

Serious infections caused by Trichosporon beigelii have been noted with increasing frequency in immuno-compromised patients. Progress in understanding the pathogenesis of this emerging infection has been limited by the lack of an animal model. We developed a CF1 mouse intravenous inoculation model of disseminated trichosporonosis to evaluate the pathogenicity of T. beigelii in transiently immunosuppressed mice. Four inocula (1 x 10(6), 1 x 10(7), 2 x 10(7), and 4 x 10(7) CFU per animal) of one clinical strain of T. beigelii 3001 were tested. Mice in groups of 10 were each injected with a single intravenous dose of one inoculum. Mortality correlated with inoculum size, as survival time was significantly shorter in mice injected with 4 x 10(7) or 2 x 10(7) CFU than in mice that received 1 x 10(7) or 1 x 10(6) CFU (P less than 0.01). Necrotizing abscesses with conidial and hyphal elements and neutrophil and macrophage infiltration were observed in all major organs examined. Resistance to infection was markedly lowered by immunosuppression with either cyclophosphamide or cortisone acetate, with a significantly shorter survival time and a greater fungal burden per organ in immunosuppressed animals than in normal animals (P less than 0.01). Nine additional strains were inoculated intravenously with around 5 x 10(6) CFU. Injection of each of these strains caused 100% mortality, in a pattern similar to that observed with strain 3001.

A fatal infection due to Fusarium oxysporum in a child with Wilms' tumour. Case report and review of the literature

Fusarium oxysporum was isolated twice from the blood culture of a 5-year-old boy with inoperable Wilms' tumour (stage IV) 4 weeks after a cytoreductive therapy with actinomycin D, vincristine and adriamycin. The child died 3 weeks after the first isolation of the fungus with signs of hepatic failure and consumptive coagulopathy. The importance of infection with Fusarium spp. in immunocompromised neutropenic patients and their pathogenetic role are discussed in the view of the literature.

Contributions to a revision of the genus Trichosporon

The genus Trichosporon was revised using characters of morphology, ultrastructure, physiology, ubiquinone systems, mol% G + C of DNA, DNA/DNA reassociations and 26S ribosomal RNA partial sequences. A total of 101 strains was used, including all available type and authentic cultures of previously described taxa. Nineteen taxa could be distinguished, 15 of which having Q-9 coenzyme systems and 4 having Q-10. Sixteen previously described names were reduced to synonymy. One new species was described. The genus is characterized by the presence of arthroconidia. Few species possess further diagnostic morphological characters, such as the presence of appressoria, macroconidia or meristematic conidiation. The septa of two species were found to be non-perforate, while those of the remaining species contained dolipores at variable degrees of differentiation, with or without vesicular or tubular parenthesomes. All species were able to assimilate a large number of carbon compounds; visible CO2 production was absent. The genus was found to be fairly homogeneous on the basis of a phylogenetic analysis of partial 26S rRNA sequences, with the exception of T. pullulans which proved to be unrelated. Most taxa were found to occupy well-defined ecological niches. Within the group of taxa isolated from humans, a distinction could be made between those involved in systemic mycoses and those which mainly caused pubic or non-pubic white piedras, respectively. One species was consistently associated with animals, while others came mainly from soil or water. One species was mesophilic and another psychrophilic.