Multifactorial aspects of antimicrobial activity of propolis.

We investigated the antibacterial activity of sub-inhibitory concentrations of ethanolic extract of propolis (EEP), and its effect on the antibacterial activity of some antibiotics. Some clinically isolated Gram-positive strains were used. Moreover, sub-inhibitory concentrations of EEP were used to value its action on some important virulence factors like lipase and coagulase enzymes, and on biofilm formation in Staphylococcus aureus. Our results indicated that EEP had a significant antimicrobial activity towards all tested clinical strains. Adding EEP to antibacterial tested drugs, it drastically increased the antimicrobial effect of ampicillin, gentamycin and streptomycin, moderately the one of chloramphenicol, ceftriaxon and vancomycin, while there was no effect with erithromycin. Moreover, our results pointed out an inhibitory action of EEP on lipase activity of 18 Staphylococcus spp. strains and an inhibitory effect on coagulase of 11 S. aureus tested strains. The same EEP concentrations showed a negative interaction with adhesion and consequent biofilm formation in S. aureus ATCC 6538P.

Antifungal activity of Lavandula angustifolia essential oil against Candida albicans yeast and mycelial form.

The antifungal activity of the essential oil of Lavandula angustifolia Mill. (lavender oil) and its main components, linalool and linalyl acetate, was investigated against 50 clinical isolates of Candida albicans (28 oropharyngeal strains, 22 vaginal strains) and C. albicans ATCC 3153. Growth inhibition, killing time and inhibition of germ tube formation were evaluated. The chemical composition of the essential oil was determined by gas chromatography and mass spectrometry. Lavender oil inhibited C. albicans growth: mean minimum inhibitory concentration (MIC) of 0.69% (vol./vol.) (vaginal strains) and 1.04% (oropharyngeal strains); mean MFC of 1.1% (vaginal strains) and 1.8% (oropharyngeal strains). Linalool was more effective than essential oil: mean MIC of 0.09% (vaginal strains) and 0.29% (oropharyngeal strains); mean MFC of 0.1% (vaginal strains) and 0.3% (oropharyngeal strains). Linalyl acetate was almost ineffective. Lavender oil (2%) killed 100% of the C. albicans ATCC 3153 cells within 15 min; linalool (0.5%) killed 100% of the cells within 30 s. The essential oil inhibited germ tube formation (mean MIC of 0.09%), as did the main components (MIC of 0.11% for linalool and 0.08% for linalyl acetate). Both the essential oil and its main components inhibited hyphal elongation of C. albicans ATCC 3153 (about 50% inhibition at 0.016% with each substance). Lavender oil shows both fungistatic and fungicidal activity against C. albicans strains. At lower concentrations, it inhibits germ tube formation and hyphal elongation, indicating that it is effective against C. albicans dimorphism and may thus reduce fungal progression and the spread of infection in host tissues.

Effect of propolis on virulence factors of Candida albicans.

Propolis is a resinous substance collected by honeybees from plant sources. Its antimicrobial activity has been well documented but little is specifically known about its activity on virulence factors of Candida albicans. The aim of this work was therefore to evaluate in vitro the propolis effect on yeast-mycelial conversion (Y-M), extracellular phospholipase activity and fungal adhesion to epithelial cells. The two propolis samples used significantly inhibited the C. albicans strains tested, showing a rapid (between 30 seconds and 15 minutes), dose-dependent cytocidal activity and an inhibitory effect on Y-M conversion at a concentration of 0.22 mg/ml. Moreover, the hyphal length was reduced even at lower propolis concentration. Propolis also caused a dose- and time-dependent inhibition of phospholipase activity. No clear effect was shown on adherence to buccal epithelial cells and surface structure hydrophobicity, but damage to the plasma membrane structure was demonstrated with the Propidium Iodide test.

Chiral discrimination by HPLC and CE and antifungal activity of racemic fenticonazole and its enantiomers.

Fenticonazole is a chiral antifungal agent, used in therapy as the racemic mixture. The investigation on the chirality of fenticonazole is reported in this study. rac-Fenticonazole was resolved by HPLC and by capillary electrophoresis (CE). The chiral stationary phase (CSP), used in HPLC, was Daicel OD-H, a commercial phase, which allowed the separate collection of the two enantiomers. The chiral selectors used for CE were some cyclodextrin derivatives. The analysis time required from CE was about the half the HPLC enantioseparation time. The biological activity of the rac-mixture and each individual enantiomer was tested against Cryptococcus neoformans and two Aspergillus nidulans strains. The minimum inhibitory concentration (MIC) evaluation showed that the eutomer was the enantiomer chromatographically more retained and had a longer migration time in the electrophoretic enantioseparation. The CD spectrum of the eutomer showed a positive Cotton effect.

In vitro activity of tea tree oil against Candida albicans mycelial conversion and other pathogenic fungi.

The antifungal activity of Melaleuca alternifolia Maiden (Myrtaceae) essential oil against yeasts (Candida spp., Schizosaccharomyces pombe, Debaryomyces hansenii) and dermatophytes (Microsporum spp. and Tricophyton spp.) is reported. We focused on the ability of tea tree oil to inhibit Candida albicans conversion from the yeast to the pathogenic mycelial form. Moreover we carried out broth microdilution test and contact tests to evaluate the killing time. M. alternifolia essential oil inhibited the conversion of C. albicans from yeast to the mycelial form at a concentration of 0.16% (v/v). The minimum inhibitory concentrations (MICs) ranged from 0.12% to 0.50% (v/v) for yeasts and 0.12% to 1% (v/v) for dermatophytes; the cytocidal activity was generally expressed at the same concentration. These results, if considered along with the lipophilic nature of the oil which enables it to penetrate the skin, suggest it may be suitable for topical therapeutic use in the treatment of fungal mucosal and cutaneous infections.

In vitro activity of propyl gallate-azole drug combination against fluconazole- and itraconazole-resistant Candida albicans strains.

AIMS: The influence of an antioxidant, propyl gallate (PG), on the in vitro antifungal activity of itraconazole and fluconazole, was investigated to determine whether PG could increase the antifungal activity and reduce strain resistance. METHODS AND RESULTS: Susceptibility tests were performed against azole-resistant isolates of Candida albicans by the microbroth dilution method in the presence of PG at 400 microg ml-1. PG-triazole combination brought about a marked reduction of inhibitory azole concentration. In particular, the MIC90 for itraconazole and fluconazole dropped from 1 microg ml-1 to 0.125 microg ml-1 and from > 64 microg ml-1-8 microg ml-1, respectively. CONCLUSION: It is likely that more than one mechanism is involved in the above synergistic interaction, including effects of PG on ATP synthesis, thus reducing the ABC transporters activity, or an effect on the target of azole, i.e. the P-450 cytochrome. SIGNIFICANCE AND IMPACT OF THE STUDY: The PG-triazole combination may have a role in future topical antifungal strategies but other studies are warranted.

Anticandidal activity of SPA-S-843, a new polyenic drug.

The activity of a new, soluble and stable polyene (SPA-S-843) against Candida albicans was assessed by contact and culture tests and by inhibition of germ-tube formation. The drug demonstrated a higher contact activity and lower MICs than amphotericin B. This antimicrobial activity was more evident under acid pH and low ionic strength. In addition, the ability of SPA-S-843 to inhibit Candida sp. conversion from yeast to mycelial form was evident at low drug concentrations (0.25-0.62 mg/L).

Antifungal activity of ketoconazole and other azoles against Malassezia furfur in vitro and in vivo.

The in vitro activity of several antifungal agents (ketoconazole, miconazole, econazole, fenticonazole, itraconazole, fluconazole) in routine clinical use against Malassezia furfur infections has been studied with freshly isolated strains of M. furfur from pityriasis versicolor lesions. The results indicate that the drugs tested exert a good activity, and both ketoconazole and itraconazole appear very active (0.8 mg/l respectively). Hair samples from the beards of volunteer patients affected by pityriasis versicolor but otherwise healthy were examined to determine ketoconazole levels during oral therapy (one or two 200 mg tablets daily). It was shown that the drug progressively accumulates in the beard, reaching levels proportional to the dose administered, although blood levels did not increase in parallel. The study of drug concentration profile has evidenced a long ketoconazole persistence in the beard at therapeutic levels. In conclusion, the possibility of reaching high and lasting ketoconazole levels in the keratin layer of the epidermis indicates that systemic ketoconazole therapy could be useful for eradication of M. furfur in patients affected by pityriasis versicolor.

In vivo and in vitro antifungal activity of the polyene derivative SPA-S-753 against encapsulated form of Cryptococcus neoformans.

The in vitro and in vivo activity of SPA-S-753 (N-dimethylaminoacetyl-partricin A 2-dimethylaminoethylamide diaspartate), a new water soluble polyene, was compared with amphotericin B against Cryptococcus neoformans in encapsulated (K) and nonencapsulated (N) morphological forms. In vitro tests against 17 isolates of C. neoformans (in K or N form) showed that SPA-S-753 activity is about ten times higher than that of amphotericin B. In direct contact tests the SPA-S-753 cytocidal action was significantly higher than that of amphotericin B; the K cells are, however, less sensitive to the cytocidal action exerted by the two polyenes even when using concentrations 4-fold higher than those used against the N cells and they present a smaller potassium ion release. The cytocidal activity of the two polyenes is favoured by a low electrolyte concentration and an acid pH. SPA-S-753 microbicidal activity by contact in vivo, in mice infected with C. neoformans N cells by i.p. route, is more powerful than that of amphotericin B. In protection tests in mice infected with 10 LD50 of C. neoformans K cells, SPA-S-753 action is again more powerful, but not to a significant degree, than that of amphotericin B. In conclusion, both substances showed a reduced in vitro and in vivo activity against C. neoformans in the K morphological form. Nevertheless our results demonstrate that SPA-S-753 exerts an antifungal overall activity that is more effective than that of amphotericin B under similar experimental conditions.

Antimicrobial contact activity of econazole sulfosalicylate.

The aim of this investigation was to compare the contact action of econazole sulfosalicylate (E-SSA) on mycetes (Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus, Trichophyton rubrum, T. cutaneum, Pityrosporum sp.), Gram-positive bacteria (Staphylococcus aureus, Streptococcus faecalis) and Gram-negative bacteria (Escherichia coli, Citrobacter freundii) with that exerted by econazole nitrate (E-NIT). The results show E-SSA activity greater than E-NIT (in particular against mycetes and Gram-negative bacteria). The E-SSA contact activity trials illustrated certain properties of this imidazole sulfosolicylate such as: absence of latency time, antimicrobial activity proportional to its concentration, when a high concentration is used, given the limiting influence of pH and ionic strength of the medium. The higher E-SSA contact activity, in relation to E-NIT, can be correlated to its greater lipophylia considering also the lipophylic properties of SSA and the scarce dissociation of E-SSA.

Increased in vitro sensitivity of Candida albicans to fluconazole.

Sodium dioctyl sulfosuccinate (SDSS), an anionic surfactant used at a non-antimicrobial concentration, increased the sensitivity of Candida albicans to fluconazole in complex media (such as Sabouraud). The conditions were assessed to determine the in vitro sensitivity to fluconazole. In this connection, the use of a liquid medium at a non-alkaline pH is important. The presence of SDSS in complex media does not seem to affect the neutralization of a particular substances but favours the activity of fluconazole.

Investigations of the activity by contact of miconazole sulfosalicylate.

The in-vitro antimicrobial activity of miconazole sulfosalicylate (M.SSA) has been investigated on mycetes (Candida albicans, Cryptococcus neoformans, Aspergillus niger, Trichophyton mentagrophytes), Gram-positive bacteria (Staphylococcus aureus, Streptococcus faecalis) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens and Proteus vulgaris) in comparison with miconazole nitrate (M.NIT). The results showed M.SSA has a greater activity than M.NIT, particularly on mycetes and Gram-negative bacteria. The study of activity by contact with M.SSA showed some characteristics of this sulfosalicylate imidazole, such as the lack of a latency time, an antimicrobic action related directly to the concentration, the limited influence of pH and ionic strength of medium used. The greater activity by contact of M.SSA than M.NIT could be related to its higher lipophilia (due also to the lipophilic characteristics of SSA) and, therefore, to increased interaction with the cell membrane.

In vitro antimicrobial activity of econazole and miconazole sulfosalicylate.

The in vitro activities of new sulfosalicylic salts of econazole (E.SSA) and miconazole (M.SSA) have been investigated in comparison with the respective nitrate (NIT) salts and sulfosalicylic acid (SSA) alone. The results reveal good antimicrobial activity of M.SSA and E.SSA against different strains of Candida, dermatophytes, moulds, Gram-positive bacteria and Trichomonas vaginalis. The MIC values demonstrate that M.SSA is more active than M.NIT on Candida and T. vaginalis. E.SSA was also more active than E.NIT on T.vaginalis. Both SSA and sodium sulfosalicylate (NaSSA) were practically without activity by themselves. Finally, the pH variations did not significantly modify the activity of the SSA salts, suggesting that their greater activity could be due to better lipophilic activity of these compounds with respect to the nitrate salts.

[Antimicrobial activity exerted by sodium dichloroisocyanurate]. / Studio dell'attività antimicrobica esercitata dal dicloroisocianurato di sodio.

Sodium dichloroisocyanurate is a chlorinated cleaner. It was used for swimming pool sanitation and for the sterilisation of linen. Not recently ago sodium dichloroisocyanurate has substituted hypochlorite for the sterilisation of infant feeding bottles and teats. Sodium dichloroisocyanurate is soluble in water; this condition causes the hydrolysis of sodium dichloroisocyanurate in hypochlorous acid, that is the active agent, isocyanurate and isocyanurate chlorine. These compounds form a chlorine protein that carry out microbicidal activity. In a toxicology study has been shown that no severe changes in the normal metabolic function occurred, furthermore sodium dichloroisocyanurate has not shown teratogenic effects at the concentration of 200 mg/kg. The antimicrobial activity of sodium dichloroisocyanurate was evaluated against Gram negative bacteria such as E. coli or Salmonella typhimurium and against some fungi. This study illustrates a rapid antimicrobial activity using concentrations. Our study concentrated on the antimicrobial activity of sodium dichloroisocyanurate in some experimental conditions. We tested 66 strains of fungi, 28 Gram positive bacteria and 29 Gram negative bacteria. We also evaluated the antimicrobial activity of sodium dichloroisocyanurate against protozoa such as Trichomonas vaginalis. The antimicrobial activity was evaluated in cultural conditions and non cultural conditions; in these experiments we observed similar action in both the commercial product and pure substance. In cultural conditions sodium dichloroisocyanurate shows a good activity against fungi and bacteria, moreover it can be observed that the serum didn't interfere with its activity. In a non cultural condition the Candida was killed rapidly by the sodium dichloroisocyanurate but this activity is influenced by the growth phase of the yeast. Against mycelial form such as Penicillium and Aspergillus the sodium dichloroisocyanurate needs a longer contact time than yeast form for its activity. It is interesting to note that well known bacteria, that are resistant to the common antimicrobial agents, such as Pseudomonas aeruginosa, were inhibited by sodium dichloroisocyanurate in a rapid bactericidal action. Our data demonstrates that no significant adverse influence on the activity of sodium dichloroisocyanurate was shown by pH and by temperature even if in some experimental conditions increased activity was noticed at pH = 6.6. The sodium dichloroisocyanurate has demonstrated good activity against Trichomonas vaginalis. This fact extends the broad-spectrum activity of sodium dichloroisocyanurate to the protozoa. In conclusion, sodium dichloroisocyanurate has demonstrated a good activity against all tested strains, furthermore its activity did not decrease in the presence of 1% of organic substance (serum etc.).(ABSTRACT TRUNCATED AT 400 WORDS)

[Antimicrobial characteristics of a tincture of dequalinium chloride]. / Caratteristiche antimicrobiche di una tintura al dequalinio cloruro.

Dequalinium is a quaternary ammonium salt. From about 30 years Dequalinium (D.C.) was used in the treatment of the initial respiratory organs infections. It can be given orally and topically yet it cannot be given systemically cause its probable systemic toxicity. D.C. has a wide range of antimicrobial activity that is extended to Gram positive, Gram negative bacteria, protozoa and yeast. Its mechanism of action is directed to the cytoplasmatic membrane where D.C. caused its damage and consequently release of cellular components. Our study has been evaluated the antimicrobial activity of D.C. both as commercial product that pure substance. We tested 27 Gram positive bacteria, 49 Gram negative bacteria, 83 strains of fungi, we also tested the antimicrobial activity of D.C. commercial product and pure substance against 8 strains of protozoa; Trichomonas vaginalis. The antimicrobial activity was estimated in some experimental conditions, (cultural and no cultural conditions); in these experiments we can observed that the commercial product presents higher activity than pure substance. In cultural condition commercial product presents antimicrobial activity against Gram positive and negative bacteria and yeast; its interesting to evaluate that bacteria, that are resistant to the common antimicrobial agents were inhibited by D.C. tinture and pure substances. Our data exhibit that serum didn't interfere until the 2% concentration with the antimicrobial activity of D.C., moreover this antimicrobial activity is not influenced by the inoculum size until 10(5) cell/ml. D.C. presents higher activity at alkaline pH than acid pH but strains of C. albicans were killed by D.C. at acid pH. In no cultural conditions D.C. has demonstrated a rapid antimicrobial activity in short contact time (15 minute); the cells of some microorganisms were killed in 60 minutes. Against mycelial form, the commercial product demonstrates good activity higher than pure substance. The activity of D.C. against the formation of germ-tube from blastospores of C. albicans in N-acetyl-glucosamine solution (no culture medium) was markedly high; this is very important because in C. albicans the germ-tube production and yeast-mycelial conversion are prominent for pathogenicity and resistance to host defences. Our data demonstrate the good activity of D.C. against Trichomonas vaginalis; we can also observed that the antimicrobial activity of commercial product is higher than pure substance.(ABSTRACT TRUNCATED AT 400 WORDS)

Glycogen medium, antitrichomonal drug activity in vaginal liquids.

The amount of glycogen in vaginal liquids decreases with Trichomonas vaginalis and this is connected with T. vaginalis activity in specimens. A glycogen-hydrolysed casein medium ("glycogen medium") added to vaginal liquid is a valid maintenance medium for T. vaginalis and therefore enables a direct test for antitrichomonas drugs to be performed.

[Substances with antibacterial and antifungal activity. VII. Synthesis and microbiologic activity of new derivatives of 1,5-diarylpyrrole]. / Ricerche su sostanze ad attività antibatterica ed antifungina. Nota VII--Sintesi ed attività microbiologica di nuovi derivati dell'1,5-diarilpirrolo.

The synthesis and antifungal activities of new 1,5-diarylpyrrole derivatives are reported. Antimicrobial data in comparison with pyrrolnitrin show that N-methylpiperazinylamides exhibit very poor activity against Candida albicans and Candida sp. while acid and ester derivatives are inactive. Vice-versa many acid or amide derivatives show interesting antibacterial activity. The results obtained are discussed on the basis of structure-activity relationships.

A study of the antifungal activity of LY121019, a new echinocandin derivative.

LY121019 is a cyclic peptide antibiotic of the echinocandin group, which is characterized by strong anti-Candida activity (in particular against Candida albicans) as well as by low experimental toxicity. Its anti-Candida activity is thought to be due to an inhibition of the synthesis of beta-glucan, an essential cell wall polysaccharide. The different composition of culture media or the presence of animal serum did not show adverse effects on LY121019's anti-Candida activity and the addition of reducing compounds such as cysteine and hydroquinone did not manifest a negative influence. Analogously the anti-Candida activity was not influenced when C. albicans was grown under aeration. The activity of LY121019 was very high against the mycelial form of C. albicans even when this form was developed in the presence of animal serum.