In vitro and in vivo antifungal activities of liposomal amphotericin B,and amphotericin B lipid complex

The in vitro and in vivo antifungal activities of liposomal amphotericin B (L-AMPH) and amphotericin B lipid complex (ABLC), which is composed of amphotericin B and the phospholipids dimyristoyl phosphatidylcholine and dimyristoyl phosphatidylglycerol, were compared with those of conventional amphotericin B (Fungizone®, AMPH). The acute intravenous toxicity was markedly lower in BALB/c mice; 50% lethal doses (LD_50s) were 2.75 mg/kg in AMPH, 32.9 mg/kg in L-AMPH and >75 mg/kg in ABLC. In vitro antifungal activities againstCandida albicans, C. parapsilosis, C. tropicalis, C. glabrata, andC. krusei were evaluated by the agar plate dilution method. The activities were unchanged againstC. albicans, but MICs increased more than four fold in 18 of the 20 strains other thanC. albicans in L-AMPH and in 9 of the 20 in ABLC. L-AMPH and ABLC were as efficacious as AMPH in the treatment of mice infected withC. albicans, and at a dose of 0.5 and 1.0 mg/kg of body weight, ABLC was more efficacious on survival. A ten-times larger dose (10 mg/kg) of L-AMPH and ABLC was administered to mice with 100% survival, suggesting improved tolerability as compared to amphotericin B.     

Comparative study of four antifungal drugs in an experimental model of murine cryptococcosis

A comparative study among amphotericin B, 5-fluorocytosine, itraconazole and fluconazole in the treatment of experimental cryptococcosis in mice, was carried out.Seventy male Balb C mice were inoculated intraperitoneally with 10⁷ cells of Cryptococcus neoformans var. neoformans. They were divided in 7 groups of 10 animals each one: 1) treated with fluconazole by gavage at a daily dose of 16 mg/kg; 2) treated with itraconazole by gavage at a daily dose of 16 mg/kg; 3) treated with 5-fluorocytosine by gavage at a daily dose of 300 mg/kg; 4) treated with amphotericin B intraperitoneally at a dose of 6 mg/kg every other day; 5) control animals receiving polietilenglicol 200 by gavage; 6) control animals receiving distilled water by gavage and 7) control animals receiving sterile distilled water by intraperitoneal route. All the treatments started 5 days after the challenge inoculation and they were given for 2 weeks.The following parameters were taken into account: survival time, macroscopic aspect of the organ after the complete autopsy, microscopic investigation of yeasts in brain, lungs, spleen and liver, histopathology studies of these organs, the colony forming units per gram and massive seeding of brain and lungs.The survival index of the different groups was the most efficient method to measure the antifungal compounds activity. Amphotericin B increased significantly the animals survival and modified the histopathologic response in the studied organs. The colony forming units and the massive seeding in brain and lung showed that this antifungal agent is unable of producing the biological cure of this experimental model.The remaining drugs assayed did not promote important modifications in the histopathologic picture as well as in the tissues cultures. However, the three drugs increased the animals survival. In this aspect, fluconazole proved to be slightly superior.     

Antifungal Activity of Antifungal Drugs,as Well as Drug Combinations Against <Emphasis Type="Italic">Exophiala dermatitidis</Emphasis>

To evaluate the in vitro efficacy of common antifungal drugs, as well as the interactions of caspofungin with voriconazole, amphotericin B, or itraconazole against the pathogenic black yeast Exophiala dermatitidis from China, the minimal inhibitory concentrations (MICs) of terbinafine, voriconazole, itraconazole, amphotericin B, fluconazole, and caspofungin against 16 strains of E. dermatitidis were determined by using CLSI broth microdilution method (M38-A2). The minimal fungicidal concentrations (MFCs) were also determined. Additionally, the interactions of caspofungin with voriconazole, amphotericin B, itraconazole or fluconazole, that of terbinafine with itraconazole, or that of fluconazole with amphotericin B were assessed by using the checkerboard technique. The fractional inhibitory concentration index (FICI) was used to categorize drug interactions as following, synergy, FICI ≤ 0.5; indifference, FICI > 0.5 and ≤4.0; or antagonism, FICI > 4.0. The MIC ranges of terbinafine, voriconazole, itraconazole, amphotericin B, fluconazole, and caspofungin against E. dermatitidis were 0.06–0.125 mg/l, 0.25–1.0 mg/l, 1.0–2.0 mg/l, 1.0–2.0 mg/l, 16–64 mg/l, and 32–64 mg/l, respectively. The in vitro interactions of caspofungin with voriconazole, amphotericin B, and itraconazole showed synergic effect against 10/16(62.5%), 15/16(93.75%), and 16/16(100%) isolates, while that of caspofungin with fluconazole showed indifference. Besides, the interaction of terbinafine with itraconazole as well as that of fluconazole with amphotericin B showed indifference. Terbinafine, voriconazole, itraconazole, and amphotericin B have good activity against E. dermatitidis. The combinations of caspofungin with voriconazole, amphotericin B or itraconazole present synergic activity against E. dermatitidis. These results provide the basis for novel options in treating various E. dermatitidis infections.     

Treatment of systemic candidiasis in a neutropenic murine model using immunoglobulin G bearing liposomal amphotericin B

Efficacy of immunoglobulin G (IgG) bearing liposomal amphotericin B (LAMB-IgG), liposomal amphotericin B without IgG (LAMB) or free amphotericin B (fAMB/Fungizone) was investigated in the treatment of systemic candidiasis in a neutropenic mouse model. Treatment with a single dose (0.6 or 0.9 mg amphotericin B per kg body weight) of LAMB-IgG resulted in a significant increase in the survival rate of neutropenic mice infected with 3×10⁵ cfu ofCandida albicans compared to untreated controls, mice injected with IgG, or liposome alone. Survival was also better in neutropenic mice treated with LAMB-IgG than in neutropenic mice treated with the same dose of LAMB or fAMB. Moreover, 65% of all mice survived the infection after treatment with a single dose of 0.6 mg AMB of the LAMB-IgG formulation. Quantitative culture counts of organs showed that both fAMB and LABM-IgG formulations even at a dose of 0.3 mg AMB/kg, clearedC. albicans from the spleens, livers, and lungs but not from the kidneys. However, a decreasd number ofC. albicans cells was recovered from the kidneys of mice that survived the infection. Results of the study suggest that LAMB-IgG is more effective than LAMB or fAMB in the therapy of disseminated candidiasis in neutropenic mice.     

Fluconazole Non-susceptible <Emphasis Type="Italic">Cryptococcus neoformans</Emphasis>, Relapsing/Refractory Cryptococcosis and Long-term Use of Liposomal Amphotericin B in an AIDS Patient

The treatment of cryptococcosis is hampered by inefficacy or intolerance to the recommended antifungal agents. A patient diagnosed with AIDS had multiple relapses of cryptococcal infection, which became refractory to antifungal agents during the course of therapy. During the follow-up, the patient developed renal toxicity due to amphotericin B use and non-susceptibility of isolated Cryptococcus neoformans to fluconazole was detected. Thereafter, antifungal treatment was performed exclusively with liposomal amphotericin B, reaching a cumulative dose of 19,180 mg over 46 months. The final relapse of cryptococcosis occurred during the maintenance phase with liposomal formulation in a once-weekly dose. Measurement of the minimum serum concentrations of amphotericin B, determined sequentially before and after this relapse, suggested the importance of monitoring drug levels when the liposomal formulation is used for a long period.     

Synthesis and antifungal activity of 1,2,3-triazole containing fluconazole analogues

Fluconazole based novel mimics containing 1,2,3-triazole were designed and synthesized as antifungal agents. Their antifungal activities were evaluated in vitro by measuring the minimal inhibitory concentrations (MICs). Compounds 12, 15, and 16 were found to be more potent against Candida fungal pathogens than control drugs fluconazole and amphotericin B. The studies presented here provide structural modification of fluconazole to give 1,2,3-trazole containing molecules. Furthermore, these molecules were evaluated in vivo against Candida albicans intravenous challenge in Swiss mice and antiproliferative activities were tested against human hepatocellular carcinoma Hep3B and human epithelial carcinoma A431. It was found that compound 12 resulted in 97.4% reduction in fungal load in mice and did not show any profound proliferative effect at lower dose (0.001 mg/ml).     

Animal Models and Antifungal Agents in Paracoccidioidomycosis: An Overview

Paracoccidioides brasiliensis is the etiologic agent of paracoccidioidomycosis, the most prevalent systemic mycosis in Latin America. The morbidity and mortality associated with paracoccidioidomycosis necessitate our understanding of fungal pathogenesis and discovering of new agents to treat this infection. Animal models have contributed much to the knowledge of fungal infections and their corresponding therapeutic treatments. This is true for animal models of the primary fungal pathogens such as P. brasiliensis. This review describes the development, details and utility of animal models of paracoccidioidomycosis for studying and developing the current antifungal agents used for therapy of this fungal disease and novel agents with antifungal properties against P. brasiliensis.     

Direct Comparison of the Efficacy and Safety of Oral Treatments with Oleylphosphocholine (OlPC) and Miltefosine in a Mouse Model of L. major Cutaneous Leishmaniasis

Background

Cutaneous leishmaniasis (CL) represents a range of skin diseases caused by infection with Leishmania parasites and associated with tissue inflammation and skin ulceration. CL is clinically widespread in both the Old and New World but lacks treatments that are well tolerated, effective and inexpensive. Oleylphosphocholine (OlPC) is a new orally bioavailable drug of the alkylphosphocholine family with potent antileishmanial activity against a broad range of Leishmania species/strains.

Methodology/principal findings

The potential of OlPC against Old World CL was evaluated in a mouse model of Leishmania (L.) major infection in BALB/c mice. Initial dose-response experiments showed that an oral daily dose of 40 mg/kg of OlPC was needed to impact time to cure and lesion sizes. This dose was then used to directly compare the efficacy of OlPC to the efficacy of the antileishmanial drugs miltefosine (40 mg/kg/day), fluconazole (160 mg/kg/day) and amphotericin B (25 mg/kg/day). OlPC, miltefosine and fluconazole were given orally for 21 days while amphotericin B was administered intraperitoneally for 10 days. Ulcer sizes and animal weights were followed up on a weekly basis and parasitemia was determined by means of a real-time in vivo imaging system which detects luminescence emitted from luciferase-expressing infecting L. major parasites. Amphotericin B and OlPC showed excellent efficacy against L. major lesions in terms of reduction of parasitic loads and by inducing complete healing of established lesions. In contrast, treatment with miltefosine did not significantly affect parasitemia and lesion sizes, while fluconazole was completely ineffective at the dose regimen tested.

Conclusions/Significance

Given the data showing the outstanding efficacy and tolerability of OlPC, our results suggest that OlPC is a promising new drug candidate to improve and simplify current clinical management of L. major CL.     

The impact of polyene,azole, and DNA analogue antimycotics on the cell surface hydrophobicity of Candida albicans and Candida tropicalis in HIV infection

Oral candidiasis is the most common opportunistic infection in individuals infected with the human immunodeficiency virus. Though Candida albicans is the major aetiological agent, non-albicans species such Candida tropicalis are now emerging as important agents of such infection. The Candida cell surface hydrophobicity (CSH) is considered a critical factor contributing to its colonization potential and virulence. It is also known that brief exposure to sub-cidal concentrations of antifungal agents is a likely scenario in the oral environment where the administered drugs are diluted continuously due to the flushing action of saliva. Hence the objective of the present study was to compare the CSH of 10 isolates each of C. albicans and C. tropicalis from HIV-infected individuals following brief exposure (1hour) of isolates to sub-therapeutic concentrations of nystatin, amphotericin B, ketoconazole, fluconazole and 5-flurocytosine. The CSH was assessed by a previously described biphasic aqueous-hydrocarbon assay. The mean percentage reduction of CSH of C. albicans following brief exposure to nystatin, amphotericin B, ketoconazole, fluconazole and 5-flurocytosine was27.33 (p < 0.001), 21.34 (p < 0.05), 11.74 (p > 0.05), 18.4 (p > 0.05) and 14.64 (p > 0.05) respectively. The mean percentage reduction of CSH of C. tropicalis following brief exposure to nystatin, amphotericin B, ketoconazole, fluconazole and 5-flurocytosine was 33.81 (p < 0.01), 28.88 (p < 0.01), 12.6 (p > 0.05), 21.53(p > 0.05) and 17.68 (p > 0.05) respectively. A significant inter-species variation in CSH was observed for nystatin and amphoterecin B. Overall the results reveal that the CSH of C. albicans is affected to a significantly lesser degree compared with C. tropicalis when exposed to the antifungals. These data further illustrate another mode of action of antifungals on Candida leading to a reduction in the CSH and thereby the yeast adherence to host tissues. This revised version was published online in June 2006 with corrections to the Cover Date.     

Study of embryotoxic and teratogenic effects of amphotericin B and a methyl derivative of amphotericin B in rats after their intravenous and intra-amniotic administration]

The embryotoxic action of amphotericin B and its methyl derivative was compared in rats after their intravenous and intraamniotic administration. The concentrations of amphotericin B and its methyl derivative in the amniotic cavity on days 13, 14 and 15 of pregnancy were 1.5 and 36 micrograms/ml, respectively. When administered intravenously during the preimplantation period the antibiotics had no embryotoxic action. Intravenous administration of amphotericin B in a dose of 500 micrograms/kg and its derivative in a dose of 2000 micrograms/kg during organ genesis induced a decrease in the craniocaudal size. In a dose of 3000 micrograms/kg administered intravenously the methyl derivative of amphotericin B induced an increase in postimplantation death rates. Administration of amphotericin B to the amniotic cavity had no damaging action. Administration of the methyl derivative on day 15 of pregnancy led to anomalous development of the lower extremities and slower ossification. The threshold doses by the embryotoxic action for intravenous administration are 500 micrograms/kg for amphotericin B and 2000 micrograms/kg for the methyl derivative. Administration of the antibiotics to the amniotic cavity revealed potential teratogenic properties of the amphotericin B methyl derivative.     

Evaluation of Systemic Antifungal Agents in X-Irradiated Mice

The effect of X irradiation on the survival time of animals experimentally infected with pathogenic fungi was studied, and the activity of antifungal agents in pre-irradiated hosts was evaluated. A 24-hr preinfection dose of X irradiation decreased the survival time of mice infected with Cryptococcus neoformans and Histoplasma capsulatum to a greater extent than Candida albicans or Blastomyces dermatitidis infections. Exposure to 400 r caused a significant reduction in the variation (S(2)) survival time of C. albicans or H. capsulatum mouse infections. A single 100-mg/kg dose of 5-fluorocytosine or amphotericin B administered within 24 hr postinfection significantly extended the survival time of mice infected with C. albicans. Delayed treatment with amphotericin B was effective against C. neoformans infections. Four 50-mg/kg doses of 5-fluorocytosine were more effective than a single 200-mg/kg dose against C. neoformans infections. A single dose of amphotericin B provided significant protection when administered 48 hr postinfection against B. dermatitidis in preirradiated mice. A single dose of saramycetin 48 hr postinfection was highly effective against H. capsulatum mouse infections. A 100-mg/kg dose of amphotericin B was only effective against this fungal pathogen when administered within 8 hr postinfection. In vivo activity of the antifungal agents studied was detected within 8 to 14 days. The relative in vivo activity of several antifungal agents indicated the importance of considering their individual pharmacological properties for optimum effectiveness. The experimental model used in this study should be useful for the detection and for the preclinical evaluation of new antifungal agents.     

Enzymatic Activity,Sensitivity to Antifungal Drugs and <Emphasis Type="Italic">Baccharis dracunculifolia</Emphasis> Essential Oil by <Emphasis Type="Italic">Candida</Emphasis> Strains Isolated from the Oral Cavities of Breastfeeding Infants and in Their Mothers’ Mouths and Nipples

Candida strains can cause oral candidosis, as well as nipples candidosis and lead to premature weaning or yeast transmission. The aim of this study was to evaluate 51 Candida isolates obtained from the oral cavities of infants during breastfeeding and mothers’ oral cavities and nipples, their enzymatic activity and their sensitivity to amphotericin B, fluconazole and Baccharis dracunculifolia essential oil. Among the studied strains, 96.1% produced phospholipase and 78.4% produced proteinase. The antifungal resistance was only observed among isolates of C. albicans, for which three strains showed a resistant activity to fluconazole and one showed a resistant activity to amphotericin B. All strains were sensitive to B. dracunculifolia essential oil with MIC between 0.2 and 6.25 mg/ml. It was concluded that most of the strains showed significant enzymatic activity and were sensitive to amphotericin B and fluconazole. B. dracunculifolia essential oil inhibited the growth of all strains, including the ones resistant to commercial antifungal agents.     

Treatment of disseminated histoplasmosis in hamsters

A comparative study between itraconazole, ketoconazole and amphotericin B in the treatment of experimental histoplasmosis in hamsters was carried out.Seventy five animals were inoculated intracardiacally with the yeast-phase of Histoplasma capsulatum. They were divided in 5 groups: 1) treated with itraconazole by gavage (g) at a daily dose of 16 mg/kg; 2) treated with ketoconazole by (g) at a daily dose of 80 mg/kg; 3) treated with amphotericin B intraperitoneally (i.p.) at 6 mg/kg every other day; 4) control animals receiving distilled water i.p. and 5) control animals receiving P.E.G. 200 by (g). All the treatments were started one week after the challenge inoculation and they were given for 21 days. The results were evaluated by autopsy of all the animals one week after the end of the treatments. The following determinations were taken into account: microscopic examinations of spleen, liver and lungs and cultures of the spleen with determination of colony forming units/g.All the antifungal drugs used in this study were able to cause negative microscopic examinations of the liver, spleen and lungs; but only amphotericin B produced culture negative results. Itraconazole and ketoconazole presented 66% and 86% of positive cultures respectively, nevertheless the C.F.U. were lower than those obtained in control groups.In these experimental conditions amphotericin B seems to be more active than the azolic compounds and itraconazole is slightly superior to ketoconazole at a lower dose.     

In vitro activity of fluconazole and amphotericin B against Candida inconspicua clinical isolates as determined by the time-kill method

Candida inconspicua is an emerging pathogen in immunocompromised patients possessing inherently decreased susceptibility to fluconazole. We determined the MICs and killing activity of fluconazole and amphotericin B against C. inconspicua clinical isolates as well as reference strain C. inconspicua ATCC 16783 for comparison. MICs were determined using the standard broth microdilution method. Killing rates were determined using time-kill methodology at 0.5-16 x MIC fluconazole and amphotericin B concentrations. Fluconazole and amphotericin B MIC values varied between 16-128 mg/l and 0.5-1 mg/l, respectively. In time kill-assays fluconazole showed fungistatic effect at 1-16 x MIC concentrations against all tested strains after 24 h-incubation, but became fungicidal after 48 h at 4-16 x MIC concentrations. The time necessary to achieve fungicidal endpoint at 1 mg/l amphotericin B concentration ranged from 2 to 24 h. Our in vitro results confirm the data that fluconazole is ineffective against C. inconspicua at the fluconazole serum concentration attainable in humans. Amphotericin B due to its rapid killing activity seems to be a good alternative for the treatment of infections caused by C. inconspicua.     

Ketoconazole in the treatment of experimental murine paracoccidioidomycosis

In a murine model of chronic disseminated paracoccidioidomycosis (strain 18; intravenous route), Ketoconazole (200 mg/kg in 0.2% agar) was given daily by gavage in three different schedules. Continuous treatment from an early stage of infection (day 3) up to week 20 was the most effective protocol, leading to remission of histopathological lesions and of both humoral and cellular anti-P. brasiliensis immune response, and clearance of the fungus in lungs; only 1 treated animal at week 20 showed pulmonary granulomas, although less extensive than control mice. Continuous treatment from early stage up to week 8, followed by a 16 week-period of drug discontinuity, caused remission of lesions in all but 3 treated mice which showed active pulmonary paracoccidioidomycosis similar to controls (14.2% of unresponsiveness to treatment). The continuous Ketoconazole protocol since a late stage of infection (week 4) up to week 20 produced a slower remission of lesions and immune response when compared with the first drug schedule. In this model of paracoccidioidomycosis, Ketoconazole showed no detectable side-effects and was a very effective drug especially in a prolonged administration protocol from an early stage of infection.     

The oral route in the pathogenesis of paracoccidioidomycosis: An experimental study in BALB/c mice infected with P. brasiliensis Conidia

Due to the high frequency of oral mucosal lesions observed in paracoccidioidomycosis patients, it was advocated that the infection was acquired by the traumatic implantation of the etiologic agent Paracoccidioides brasiliensis. Although at present this theory is considered invalid, it has not yet been excluded in experimental studies. In order to determine if intra-oral inoculation could explain the pathogenesis of paracoccidioidomycosis, 64 BALB/c mice were inoculated intra-orally with 850.000 viable P. brasiliensis conidia into the mandibular body. Animals were sacrificed at various time intervals up to 20 weeks and cultures were made from gingiva, lungs, spleen, and liver. Additionally, histopathological studies of the mandibular body were also performed. P. brasiliensis was isolated from all gingival tissues during the interval 24–72 h, indicating that the infection was active. During the 5–10 week period, the infection appeared to have been controlled at the inoculation site as cultures showed a significant reduction in colony forming units (CFU); however, at the 15–20 week period such control was lost and the fungus was recovered once more. Dissemination to other body sites was rare; thus, the lungs were involved in just one animal (2%), the liver in two (3%) and the spleen in seven (11%). The infection became established as proven by positive organ cultures, but the dissemination pattern did not correspond to the one observed in humans. Based on these findings, the intra-oral traumatic route does not appear to mimic the natural history of paracoccidioidomycosis. This revised version was published online in August 2006 with corrections to the Cover Date.     

Interruption of antifungal secondary prophylaxis in AIDS-related histoplasmosis

The clinical data of 21 patients, suffering AIDS-related histoplasmosis, who were able to interrupt antifungal secondary prophylaxis, after achieving a partial restoration of the cell mediated immunity by HAART administration, are presented. They were 16 males and five females, whose ages varied between 32 and 54 years (mean = 38.5 years). All of them presented disseminated progressive forms of histoplasmosis, with multiple locations (skin, mucous membranes, liver, spleen, lymph nodes and lungs). The majority of the cases suffered other concomitant diseases (specially tuberculosis and Kaposi sarcoma), 66.6 % of the patients had less than 50 CD4+ cells/microl at the start of treatment and the average viral burden was 278,385 RNA copies/ml. The initial treatment consisted in 400 mg/day of itraconazole, by oral route, in 14 cases and the remaining seven patients were treated with amphotericin B, intravenously, at a daily dose of 0.7 mg/kg of body weight. One patient who did not tolerate amphotericin B and presented a partial response to itraconazole, was treated with posaconazole orally at a daily dose of 800 mg. Fourteen patients received oral itraconazole at a daily dose of 200 mg as a secondary prophylaxis, the remaining three patients were treated with intravenous amphotericin B, 50 mg twice a week. After HAART for an average lapse of 16.7 months (10 to 32 months), five cases showed CD4+ cells counts above 150 cells/microl and the remaining 16 presented more than 200 cells/microl; 18 of them had undetectable viral burden and all cases were asymptomatic. The follow up after secondary prophylaxis discontinuation varied between six months and six years (mean= 33.6 months). Twenty out of 21 patients (95 %) were clinically stable, without any manifestation of relapses, including two patients who abandoned HAART. One patient, who discontinued HAART, contracted a fatal bacterial pneumonia. Even though the limited number of cases, the data presented in this study seem to suggest that it is possible to interrupt antifungal secondary prophylaxis of histoplasmosis, when the patient is clinically asymptomatic and the CD4+ cells counts are above 150 cells/microl.     

Voriconazole, Combined with Amphotericin B, in the Treatment for Pulmonary Cryptococcosis Caused by C. neoformans (Serotype A) in Mice with Severe Combined Immunodeficiency (SCID)

Cryptococcosis is a subacute or chronic systemic mycosis with a cosmopolitan nature, caused by yeast of the genus Cryptococcus neoformans. The model of systemic cryptococcosis in mice with severe combined immunodeficiency (SCID) is useful for immunological and therapeutic study of the disease in immunodeficient hosts. Amphotericin B, fluconazole and flucytosine are the drugs most commonly used to treat cryptococcosis. Voriconazole is a triazole with high bioavailability, large distribution volume, and excellent penetration of the central nervous system. The objective of this study was to evaluate treatment with amphotericin B (AMB), voriconazole (VRC), and AMB, used in combination with VRC, of experimental pulmonary cryptococcosis in a murine model (SCID). The animals were inoculated intravenously (iv) with a solution containing 3.0 × 10(5) viable cells of C. neoformans ATCC 90112, (serotype A). Treatments were performed with amphotericin B (1.5 mg/kg/day), voriconazole (40.0 mg/kg/day) and AMB (1.5 mg/kg/day) combined with VRC (40.0 mg/kg/day); began 1 day after the initial infection; were daily; and lasted 15 days. Evaluations were performed using analysis of the survival curve and isolation of yeast in the lung tissue. There was a significant increase in survival in groups treated with AMB combined with VRC, compared with the untreated group and groups receiving other treatments (P < 0.05). In the group treated only with VRC and AMB combined with VRC, there was a significant reduction (P < 0.05) in the isolation of C. neoformans in lung tissue. Amphotericin B combined with voriconazole may be an effective alternative to increasing survival and may reduce yeast in the lung tissue of mice with pulmonary cryptococcosis and SCID.     

Protective effect of prior immunization on ocular paracoccidioidomycosis in guinea pigs

The present study reproduced the experimental model of ocular paracoccidioidomycosis in guinea pigs, by the intracardiac inoculation of yeast-forms of P. brasiliensis. Ocular involvement was observed in 80% of the infected animals. The uvea, ciliary body, choroid, iris, lids and the conjunctiva were the structures most commonly affected. To protect the animals against the infection, an immunization protocol was standardized utilizing a P. brasiliensis soluble antigen in Freund's complete adjuvant, administered weekly, during 3 weeks, by the subcutaneous route. Two weeks later, previously immunized guinea pigs were challenged by the intracardiac route with yeast-forms of P. brasiliensis (vaccinated group). When compared with a control group (infection in the absence of prior immunization), the vaccinated animals developed higher levels of anti-P. brasiliensis cellular and humoral immune response and a three times lower frequency of ocular involvement (85.7% vs 28.5%). In addition, the ocular lesions were significantly more localized and contained less fungal cells. The data demonstrated that the subcutaneous immunization was effective in decreasing the frequency and extent of ocular lesions, as well as in blocking fungal multiplication.     

THIS ARTICLE HAS BEEN RETRACTEDHamycin treatment of candidiasis in normal and diabetic rats

Hamycin, a heptaene antifungal antibiotic was compared with amphotericin B in the treatment of established systemic infection with Candida albicans in normal and diabetic rats. In normal rats, orally administered hamycin at 10 mg kg(-1) per day for 7 days reduced Candida colony counts in the kidneys and livers as well as amphotericin B did and was nearly as effective as amphotericin B in a 21-day treatment trial. There was no further reduction in Candida colony counts when normal rats were treated with hamycin at 25 mg kg(-1) twice a day for 7 days. In streptozotocin induced diabetic rats, hamycin at 20 mg kg(-1) per day for either 7 or 21 days compared favourably with amphotericin B in efficacy. Results of the present study suggest that oral hamycin may be useful in the treatment of established disseminated candidiasis in normal as well as diabetic hosts.