Phosphatase Activity Among Candida Species and Other Yeasts Isolated from Clinical Material

A group of 277 yeasts isolated from burned children and 14 reference strains were tested for phosphatase activity by using phenolphthalein phosphate substrates. Phosphatase activity was widely distributed among various species and strains representing seven genera. Candida albicans, which was the most common yeast isolated from clinical material, was notably absent in producing the enzyme, whereas Candida tropicalis was the most consistent, strong, and rapidly active phosphatase-producing organism. The characteristic enzyme activity of a selected isolate of C. tropicalis was demonstrated in the presence of concentrations of inorganic phosphate which inhibited enzyme activity of other species. The greater enzyme activity of C. tropicalis was not related to more rapid or greater cell growth or decrease in the pH of culture media. Extracellular constitutive heat-labile acid phosphatase was found in broth filtrates of C. tropicalis, C. krusei, and a strain of Staphylococcus aureus.     

Antifungal Activities of Different Extracts of Marine Macroalgae Against Dermatophytes and Candida Species

Algae are bioactive natural resources, and due to the medical importance of superficial mycoses, we focused the action of macroalgae extracts against dermatophytes and Candida species. Seaweed obtained from the Riacho Doce beach, Alagoas (Brazil), were screened for the antifungal activity, through crude extracts using dichloromethane, chloroform, methanol, ethanol, water and chloroform and hexane fractions of green, brown and red algae in assays with standard strains of the dermatophytes Trichophyton rubrum, T. tonsurans, T. mentagrophytes, Microsporum canis, M. gypseum and yeasts Candida albicans, C. krusei, C. guilliermondi and C. parapsilosis. The M44-A and M27-A2/M38A manuals by CLSI were followed, and the minimum inhibitory concentration (MIC) ranged from 0.03 to 16.00 μg ml(-1), and an inhibition halo of 10.00-25.00 mm was observed for dermatophytes, while for yeast, it was from 8.00 to 16.00 μg ml(-1) and 10.00-15.00 mm. M. canis showed MIC of 0.03 μg ml(-1) and the largest inhibition halo in T. rubrum (25.00 mm) through the use of the methanol extract. For C. albicans, dichloromethane, methanol and ethanol extracts formed the largest inhibition halo. The ethanol extract was shown to be the best inhibiting fungi growth, and chloroform and hexane fractions of H. musciformis inhibited the growth of all dermatophytes and C. albicans, yielding the conclusion that apolar extracts obtained from algae presented the best activity against important pathogenic fungi.     

Antifungal Activity of Essential Oils Against Candida Species Isolated from Clinical Samples

Mycopathologia - We evaluated the in vitro antifungal activity of essential oils obtained from the aromatic plants Laurus nobilis, Thymus vulgaris, Mentha piperita, Cymbopogon citratus and Lippia...     

Antifungal and Other Biological Activities of Two 2S Albumin-Homologous Proteins Against Pathogenic Fungi

The aim of this study was to determine whether 2S albumins from Passiflora edulis f. flavicarpa and Capsicum annuum seeds inhibit growth, induce plasma membrane permeabilization and induce endogenous production of nitric oxide in different pathogenic and non-pathogenic yeasts. The 2S albumin from P. flavicarpa (Pf-Alb) inhibited the growth of Kluyveromyces marxiannus, Candida albicans and Candida parapsilosis. The membranes of these yeast strains were permeabilized in the presence of Pf-Alb. The Pf-Alb also inhibited the glucose-stimulated acidification of the medium by Saccharomyces cerevisiae and C. albicans cells, which indicates a probable impairment of fungal metabolism because the inhibition of acidification occurred at various Pf-Alb concentrations and pre-incubation times. The 2S albumin from C. annuum (Ca-Alb) inhibited the growth of the yeasts K. marxiannus, C. tropicalis, C. albicans and S. cerevisiae. These yeast strains exhibited NO induction in the presence of Ca-Alb and displayed cellular agglomeration, elongated cells and the induction of pseudohyphae. Pf-Alb and Ca-Alb at various concentrations also inhibited the glucose-stimulated acidification of the medium by S. cerevisiae cells. Our results indicate that the ability of antimicrobial plant proteins such as 2S albumins to induce microbial inhibition could be an important factor in determining pathogen virulence. Therefore, 2S albumins might be targets for the design of new antifungal drugs.     

In Vitro Activities of New Triazole Antifungal Agents, Posaconazole and Voriconazole, Against Oral Candida Isolates from Patients Suffering from Denture Stomatitis

Denture stomatitis is often treated with antifungal agents but recurrences or new episodes are common, and certain episodes can be resistant. New triazoles, such as posaconazole and voriconazole, may represent useful alternatives for management. In vitro activities of amphotericin B, nystatin, miconazole, fluconazole, itraconazole, posaconazole and voriconazole against 150 oral Candida (101 C. albicans, 18 C. tropicalis, 12 C. glabrata, 11 C. guilliermondii, 4 C. parapsilosis, 2 Saccharomyces cerevisiae, 1 C. dubliniensis and 1 C. krusei) from 100 denture wearers were tested by the CLSI M27-A3 method. Resistant isolates were retested by Sensititre YeastOne and Etest. Most antifungal agents were very active. However, 4 C. glabrata (33.3%), 2 C. tropicalis (11.1%), 6 C. albicans (5.6%) and 1 C. krusei were resistant to itraconazole. Posaconazole was active against 143 yeast isolates (95.3%): 6 C. albicans (5.9%) and 1 C. tropicalis (5.6%) were resistant. Geometric mean MICs were 0.036 μg/ml for C. parapsilosis, 0.062 μg/ml for C. albicans, 0.085 μg/ml for C. tropicalis, 0.387 μg/ml for C. guilliermondii and 0.498 μg/ml for C. glabrata. Voriconazole was active against 148 isolates (98.7%) with geometric mean MICs ranging from 0.030 μg/ml for C. parapsilosis, 0.042 μg/ml for C. albicans, 0.048 μg/ml for C. tropicalis, 0.082 μg/ml for C. guilliermondii, to 0.137 μg/ml for C. glabrata. Only 2 C. albicans (2%) were resistant to voriconazole showing cross-resistance to other azoles. Posaconazole and voriconazole have excellent in vitro activities against all Candida isolates and could represent useful alternatives for recalcitrant or recurrent candidiasis.     

Phospholipase and Proteinase Activities of Clinical Isolates of Candida from Immunocompromised Patients

Sixty-one isolates of Candida recovered from HIV seropositive and cancer patients were studied for elaboration of putative virulence determinants – phospholipase (PL) and secreted aspartyl proteinase (Sap). Forty two (68.85%) isolates examined were PL producers and 51 (83.6%) were positive for Sap. 57.37% (35/61) isolates produced both enzymes. Enzymatic activity was more pronounced in Candida albicans with 100% PL and 94.1% Sap activity. In contrast, non-C. albicans species demonstrated only 29.6% PL and 70.3% Sap activity, indicating interplay of other virulence determinants in these yeasts in colonization and disease.     

Ten-Year Study of Species Distribution and Antifungal Susceptibilities of Candida Bloodstream Isolates at a Brazilian Tertiary Hospital

To describe the incidence and susceptibility profile of Candida bloodstream infections in a tertiary-care hospital, we performed a retrospective observational study from 1998 to 2007. Comorbidities and risk factors were compiled from all cases. In vitro susceptibility testing to fluconazole, itraconazole, voriconazole, and amphotericin B was performed for 100 isolates, and caspofungin was tested for C. parapsilosis complex. In a ten-year evaluation of candidemias, 44?% were caused by C. albicans, and species of the C. parapsilosis complex were the second most frequent agents (37?%). Other species presented lower incidences (C. tropicalis, 13?%, C. glabrata, 5?%, and C. krusei, 1?%). Neither C. dubliniensis nor C. metapsilosis were observed in this study. C. orthopsilosis (3?%) and C. parapsilosis stricto sensu (34?%) were also found. Species distribution was independent of catheterization, mechanical ventilation, or previous use of antifungals or corticoids. Parenteral nutrition administration was strongly related to C. glabrata infection, and the highest mortality (80?%) was observed in patients infected by this species. All C. albicans isolates showed high susceptibility to all tested drugs. However, two C. parapsilosis stricto sensu isolates presented high minimum inhibitory concentration (MIC) (4?mg/L each) to fluconazole, and one exhibited voriconazole MIC of 0.25?mg/L, highlighting the cross-resistance to these azoles. All isolates of C. tropicalis and C. glabrata showed no resistance to any drug tested. No difference was noted between C. parapsilosis and C. orthopsilosis susceptibilities to caspofungin. Our results suggest that resistance to amphotericin B, fluconazole, voriconazole, itraconazole, and caspofungin in Brazilian Candida bloodstream isolates is still uncommon.     

Species Distribution and Antifungal Susceptibility Profile of Oral Candida Isolates from HIV-infected Patients in the Antiretroviral Therapy Era

In this study, we investigated the yeasts colonization of genus Candida, including C. dubliniensis, isolated of HIV-infected patients oral cavities and we accessed in vitro susceptibility pattern of the Candida isolates to four antifungal agents. Out of 99 patients investigated, 62 (62.6%) were colonized with yeasts. C. albicans was the prevailing species (50%). C. dubliniensis isolates were not recovered in our study. We verified that 8.1% of the yeasts isolated were resistant to fluconazole, 8.1% to itraconazole and 3.2% to voriconazole. The isolates demonstrated very low voriconazole MICs, in which 79% (49/62) presented values of 0.015 μg/ml. All Candida isolates were susceptible to amphotericin B. The results reported here showed that although C. albicans continues to be present in one-half of oral Candida carriage of HIV-infected patients, Candida non-albicans species are increasing among these patients. Besides, the findings of resistant isolates endorse the role of antifungal susceptibility testing whenever antifungal treatment with azoles is planned.     

Susceptibilities of Candida albicans Mouth Isolates to Antifungal Agents, Essentials Oils and Mouth Rinses

Forty Candida albicans strains isolated from patient's mouth with fixed orthodontic appliances were analyzed to their susceptibilities to antifungal agents, mouth rinses and essential oils. Susceptibility to fluconazole, econazole, miconazole and ketoconazole, amphotericin B and nystatin was assessed by the disk diffusion (DD) method based on the Clinical and Laboratory Standards Institute M44-A protocol, and by Etest (fluconazole and amphotericin B). The susceptibilities to mouth rinses and essential oils were also determined by the DD technique. All isolates tested were susceptible (S) to amphotericin B, nystatin and fluconazole. The overall concordance between the DD and the Etest was 100% for amphotericin and fluconazole. One isolate was resistant to econazole (2.5%) and the other to ketoconazole (2.5%). Econazole and ketoconazole had the highest percentages of susceptible dose dependent (SDD), 55 and 95%, respectively. Regarding to the susceptibility isolates profile, seven phenotypes were detected, and the 3 more represented (90% of the isolates) of them were SDD to one, two or three azoles. The study of mouth rinses showed a high variability of efficacy against C. albicans. The results showed that the isolates susceptibility to essential oils differed (P < 0.05). The profile activity was: cinnamon > laurel > mint > eucalyptus > rosemary > lemon > myrrh > tangerine. The main finding was that the susceptibility to cinnamon and laurel varied among the three more representative antifungal phenotypes (P < 0.05). The susceptibility of econazole-SDD isolates to cinnamon and lemon was higher than those of the econazole-S yeasts (P < 0.05). In contrast, econazole-SDD isolates were less affected by laurel than econazole-S counterparts (P < 0.05).     

Inhibitory Effect of Eugenol and trans-Anethole Alone and in Combination with Antifungal Medicines on Candida albicans Clinical Isolates

One of the most common pathogens among yeasts is Candida albicans, which presents a serious health threat. The study aimed to check the antifungal properties of trans-anethole and eugenol with selected antifungal medicines (AMs) against C. albicans clinical isolates. The checkerboard method was used to tests of interactions between these compounds. Achieved results indicated that eugenol showed synergistic and additive activities with miconazole and econazole against investigated clinical isolates, respectively. Moreover, the combination – trans-anethole – miconazole also showed an additive effect against two clinical isolate. We tried to relate the results to changes in C. albicans cell sheaths under the influence of essential oils compounds (EOCs) performing the Fourier transform infrared spectra analysis to confirm the presence of particular chemical moieties in C. albicans cells. Nevertheless, no strong relationships was observed between synergistic and additive actions of used EOC-AMs combinations and chemical moieties in C. albicans cells.     

Comparative In Vitro Activities of Lysostaphin and Other Antistaphylococcal Antibiotics on Clinical Isolates of Staphylococcus aureus

The in vitro activity of lysostaphin against clinical isolates of Staphylococcus aureus was determined by conventional tube-dilution methods. For comparison, minimal inhibitory concentration (MIC) values were also determined for penicillin G, ampicillin, methicillin, ristocetin, vancomycin, and erythromycin. Phage type and penicillinase and coagulase production were determined for each isolate. The MIC values for lysostaphin ranged from <0.047 to 12.5 μg/ml; 96% of the penicillinase-positive strains were inhibited by 1.56 μg/ml of lysostaphin, whereas 3.12 μg/ml of vancomycin and methicillin were required to attain the same degree of inhibition.     

Antifungal Activity of Phlorotannins against Dermatophytes and Yeasts: Approaches to the Mechanism of Action and Influence on Candida albicans Virulence Factor

In the last few decades, fungal infections, particularly nosocomial, increased all around the world. This increment stimulated the search for new antifungal agents, especially those derived from nature. Among natural products, those from marine sources have gained prominence in the last years. Purified phlorotannins extracts from three brown seaweeds (Cystoseira nodicaulis (Withering) M. Roberts, Cystoseira usneoides (Linnaeus) M. Roberts and Fucus spiralis Linnaeus) were screened for their antifungal activity against human pathogenic yeast and filamentous fungi. The purified phlorotannins extracts from the studied seaweeds displayed fungistatic and fungicidal activity against yeast and dermatophytes, respectively, pointing to their interest as anti-dermatophyte agent. C. albicans ATCC 10231 was the most susceptible among yeast, while Epidermophyton floccosum and Trichophyton rubrum were the most susceptible among dermatophytes. Since the antifungal mechanism constitutes an important strategy for limiting the emergence of resistance to the commercially available agents, the mechanism of action of purified phlorotannins extracts was approached. C. nodicaulis and C. usneoides seem to act by affecting the ergosterol composition of the cell membrane of yeast and dermatophyte, respectively. F. spiralis influenced the dermatophyte cell wall composition by reducing the levels of chitin. Phlorotannins also seem to affect the respiratory chain function, as all of the studied species significantly increased the activity of mitochondrial dehydrogenases and increased the incorporation of rhodamine 123 by yeast cells. Phlorotannins from F. spiralis inhibited the dimorphic transition of Candida albicans, leading to the formation of pseudohyphae with diminished capacity to adhere to epithelial cells. This finding is associated with a decrease of C. albicans virulence and capacity to invade host cells and can be potentially interesting for combined antifungal therapy, namely for the control of invasive candidiasis.     

Antifungal Effects of Bacilysin and Fengymycin from Bacillus subtilis F-29-3 A Comparison with Activities of Other Bacillus Antibiotics

Of the two antifungal antibiotics produced by Bacillus subtilis F-29-3, the dipeptide compound bacilysin inhibits yeasts (and bacteria), whereas the formerly unknown fengymycin, a complex of closely related lipopeptide components, shows antibiotic activity against filamentous fungi. Bacilysin production, formerly known for a few strains only, could be demonstrated for all 12 wild-type cultures of Bacillus subtilis tested during this study. The antibiotic also occurs in some strains of three other Bacillus species considered as closely realted to B. subtilis. Members of the lipopeptide class of antifungal Bacillus metabolites were formed by 8 of 12 Bacillus subtilis-isolates and several other Bacillus strains. The antibiotics of F-29-3 were compared with antifungal metabolites of other Bacillus isolates using TLC, agar-diffusion techniques and tests demonstrating the capacity of six lipopeptide and peptide preparations to protect rice seedlings from phytomycosis due to Rhizoctonia solani. Fengymycin proved to be different from the other compounds tested. It was less toxic to the test plants and protected them better from Rhizoctonia disease than the other antibiotics of the study did.     

九种蕨类植物多糖提取物抗动植物病原菌活性

从9种蕨类植物中提取多糖,以苯酚-硫酸比色法测定其含量,并采用纸片法进行抗动植物病原菌实验。结果表明,9种蕨类多糖含量差别较大,其多糖提取物表现出不同程度的抑制动植物病原菌活性。     

Effects of Antifungal Agents Alone and in Combination Against Candida glabrata Strains Susceptible or Resistant to Fluconazole

The rise of Candida spp. resistant to classic triazole antifungal agents has led to a search for new therapeutic options. Here, we evaluated combinations of antifungals in a checkerboard assay against two groups of Candida glabrata strains: one containing fluconazole-susceptible clinical isolates (FS) and another containing fluconazole-resistant laboratory derivative (FR). The most synergistic combination observed was amphotericin B + flucytosine (synergistic for 61.77 % of FS strains and 76.47 % of FR strains). The most antagonistic combination observed was ketoconazole + flucytosine (FS 61.77 % and FR 55.88 %). Surprisingly, most combinations evidenced indifferent interactions, and the best synergism appeared when amphotericin B and flucytosine were combined against both groups of isolates.     

Candida albicans and Non-C. albicans Candida Species: Comparison of Biofilm Production and Metabolic Activity in Biofilms, and Putative Virulence Properties of Isolates from Hospital Environments and Infections

Candida albicans and, more recently, non-C. albicans Candida spp. are considered the most frequent fungi in hospitals. This study analyzed Candida spp. isolates and compared the frequency of different species, that is, C. albicans and non-C. albicans Candida spp., and the origins of isolates, that is, from hospital environments or infections. Yeast virulence factors were evaluated based on biofilm production and metabolic activity. Hemolysin production and the antifungal susceptibility profiles of isolates were also evaluated. Candida spp. were highly prevalent in samples collected from hospital environments, which may provide a reservoir for continuous infections with these yeasts. There were no differences in the biofilm productivity levels and metabolic activities of the environmental and clinical isolates, although the metabolic activities of non-C. albicans Candida spp. biofilms were greater than those of the C. albicans biofilms (p < 0.05). Clinical samples had higher hemolysin production (p < 0.05) and lower susceptibility to fluconazole (p < 0.05). Non-C. albicans Candida spp. predominated in samples collected from hospital environments and infections (p < 0.05). These species had a lower susceptibility to fluconazole and amphotericin B, and their biofilms had higher metabolic activities than those produced by C. albicans, which may explain the increased incidence of fungal infections with these yeasts during recent years.     

In Vitro Activities of Fourteen Antimicrobial Agents Against Drug Susceptible and Resistant Clinical Isolates of Mycobacterium tuberculosis and Comparative Intracellular Activities Against the Virulent H37Rv Strain in Human Macrophages

Minimal inhibitory concentrations (MICs) of 14 first and second-line antituberculous drugs against drug-susceptible and drug-resistant clinical isolates of Mycobacterium tuberculosis (including the multiple drug-resistant or MDR-TB isolates), as well as the type strain H37Rv, were determined radiometrically by the Bactec 460-TB methodols. MICs (μg/ml) of all the fourteen drugs were within an extremely narrow range in case of susceptible strains; isoniazid (0.02–0.04), rifampin (0.2–0.4), ethambutol and streptomycin (0.5–2.0), ethionamide (0.25–0.5), D-cycloserine (25–75), capreomycin (1–2), kanamycin (2–4), amikacin (0.5–1.0), clofazimine (0.1–0.4), ofloxacin (0.5–1.0), ciprofloxacin (0.25–1.0), and sparfloxacin (0.1–0.4). The activity of second-line drugs remained unaltered against MDR-TB isolates resistant to routine first-line drugs. With peak serum level concentrations (Cmax), the intracellular killing of the virulent H37Rv strain was studied in detail in cultured human macrophages. Based on an decreasing order of bactericidal activity, our results showed the following spectrum of intracellular drug action: among the first-line drugs, rifampin > ethionamide = isoniazid > ethambutol > streptomycin > D-cycloserine; among second-line drugs, clofazimine = amikacin > kanamycin = capreomycin; among fluoroquinolones, sparfloxacin > ofloxacin > ciprofloxacin. On the other hand, contrary to atypical mycobacteria, the macrolide drug clarithromycin was inactive against both extracellular and intracellular M. tuberculosis. Received: 23 January 1996 / Accepted: 5 April 1996     

Lincomycin: A New Antibiotic Active Against Staphylococci and Other Gram-Positive Cocci: Clinical and Laboratory Studies

Preliminary results suggest that the antibiotic lincomycin (a product of Streptomyces lincolnensis var. lincolnensis) possesses certain valuable properties which include good in vitro activity against many strains of hospital staphylococci resistant to many other antibiotics. During a study of this agent, a selected series of severe staphylococcal infections due to resistant organisms were treated with lincomycin, with encouraging responses. Favourable results were also noted in seven cases of osteomyelitis. Lincomycin may be administered by the oral or parenteral routes to adults and infants and satisfactory serum blood levels obtained. So far as the authors'' limited experience enables them to conclude, and at the dose range tested, this antibiotic promises to be one of low toxicity.