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Effect of natamycin on the enumeration, genetic structure and composition of bacterial community isolated from soils and soybean rhizosphere.

Natamycin is commonly used to control fungal growth on agar media used for bacterial enumeration or strain isolation. However, there is no conclusive report on the possible effect of this antibiotic on bacterial growth or on the diversity of the recovered soil bacteria. Therefore, the possible effects of natamycin on the numbers of bacteria isolated at 12 degrees C from three different soils and soybean rhizosphere soil were investigated using natamycin concentrations ranging from 0 to 200 mg l(-1). Our results demonstrate that natamycin concentrations, which inhibit the growth of fungi on the media, have a small but significant inhibitory effect on the number of bacterial colony forming units. A natamycin concentration of 50-200 mg l(-1) is required for an efficient control of fungal growth on media in our experimental conditions depending on the soil type. Bacterial community structure was assessed on culturable cells (cells washed from enumeration plates: plate-wash approach) obtained at 12 degrees C from soybean rhizosphere soil by performing Ribosomal Intergenic Spacer Analysis (RISA) fingerprinting. We demonstrate that all natamycin concentrations used alter the structure of the recovered, culturable bacterial community, compared to control without natamycin. Using ARDRA (amplification of the 16S rDNA gene and restriction analysis) genotyping of individual isolates, some differences were observed between the bacterial isolates obtained in the presence or absence of natamycin. Bacterial isolates recovered in the presence of natamycin are more tolerant (maximal growth rate and lag phase) to this compound than those isolated without natamycin, indicating a possible selection of resistant strains. Therefore, high concentration of natamycin cannot be used for isolation of bacterial strains with the aim of studying biodiversity and could bias a selection of strains for practical applications.

Antifungal Agents↗

Controlled trial of natamycin in the treatment of allergic bronchopulmonary aspergillosis.

Allergic bronchopulmonary aspergillosis often requires treatment with oral corticosteroids to control the host response to Aspergillus fumigatus. In a double blind study 25 patients with allergic bronchopulmonary aspergillosis taking maintenance oral corticosteroids were randomly allocated to receive 5 mg natamycin or placebo by nebuliser twice daily for one year. The primary aim of the study was to assess the steroid sparing potential of natamycin. Standardised reductions in corticosteroid dosage were therefore undertaken every five weeks, unless clinically contraindicated. Five patients were withdrawn in the first four months: two (1 natamycin, 1 placebo) died, two (1 natamycin, 1 placebo) had suspected drug reactions, and one (natamycin) was non-compliant. The pretreatment characteristics of the 20 patients (10 in each group) who completed the study were similar, 17 (9 natamycin, 8 placebo) having evidence of recent disease activity. At the end of the study prednisolone dose had been reduced by a similar amount in each group (median natamycin 2.25 mg, placebo 2.5 mg). Evidence of disease activity during the study year (transient shadowing on the chest radiograph, blood eosinophilia, or increases in antibodies to A fumigatus, or any combination of these) was observed in similar numbers of patients in each group (5 natamycin, 7 placebo). There was no evidence that natamycin conferred benefit on these patients with allergic bronchopulmonary aspergillosis.

Adult↗

The antifungal activity of natamycin toward molds isolated from commercially manufactured poultry feed.

The antifungal activity of natamycin, a polyene antifungal compound, was evaluated on molds isolated from commercial poultry feed. The antifungal activity was measured by determination of the minimal inhibitory concentration (MIC) for natamycin on molds growing on semisolid microbiological medium (potato dextrose agar) containing pure natamycin at concentrations ranging from 0 to 200 mg/liter. Natamycin exhibited a high degree of antifungal activity against the 191 isolates of aspergilli used in this study, with average MIC values ranging from 5.08 to 40.1 mg/liter for Aspergillus fumigatus and Aspergillus parasiticus, respectively. Natamycin was also equally effective in inhibiting the growth of nonaflatoxigenic compared with aflatoxigenic isolates of Aspergillus flavus and A. parasiticus. Natamycin was also efficacious against molds other than aspergilli, with MIC values ranging from 2.15 to 5.80 mg/liter for Paecilomyces and Rhizopus spp., respectively. Natamycin exhibited apparent sporicidal activity against spores of toxigenic strains of Fusarium moniliforme and A. parasiticus but not Penicillium rubrum. This sporicidal activity was evident only when spores were exposed to an in vitro concentration of natamycin of 25 mg/liter or higher for a period of time of at least 12 hr. The growth inhibiting activity of natamycin was more pronounced compared with the sporicidal activity.

Animal Feed↗

Stability of natamycin and its cyclodextrin inclusion complexes in aqueous solution.

Aqueous solutions of natamycin and its beta-cyclodextrin (beta-CD), hydroxypropyl beta-cyclodextrin, and gamma-cyclodextrin (gamma-CD) inclusion complexes were completely degraded after 24 h of exposure to 1000 lx fluorescent lighting at 4 degrees C. After 14 days of storage in darkness at 4 degrees C, 92.2% of natamycin remained in active form. The natamycin:beta-CD complex and natamycin:gamma-CD complex were significantly more stable (p < 0.05) than natamycin in its free state in aqueous solutions stored in darkness at 4 degrees C. Clear poly(ethylene terephthalate) packaging with a UV light absorber allowed 85.0% of natamycin to remain after 14 days of storage under 1000 lx fluorescent lighting at 4 degrees C. Natamycin:cyclodextrin complexes can be dissociated for analysis in methanol/water/acetic acid, 60:40:5, v/v/v. Natamycin and its complexes in dissociated form were quantified by reverse phase HPLC with detection by photodiode array at 304 nm.

Antifungal Agents↗

Concurrent use of 5% natamycin and 2% econazole for the management of fungal keratitis.

PURPOSE: To determine if concurrent use of 5% natamycin and 2% econazole offers greater benefits than monotherapy with 5% natamycin for the management of fungal keratitis. METHODS: Subjects presenting to the cornea service were treated with 5% natamycin and 2% econazole used concurrently. We compared the results with a historical control of patients treated with 5% natamycin in the same calendar year. The same clinical and examination protocol including inclusion and exclusion criteria was used for both groups. RESULTS: We compared results of 47 subjects on concurrent use of 5% natamycin and 2% econazole with all 53 subjects who had received 5% natamycin in a previous study (historical controls). Baseline characteristics were similar between the 2 groups. There were no significant differences (P=0.9) between the 2 arms for success (defined as a healed or healing ulcer). CONCLUSIONS: Concurrent use of 5% natamycin and 2% econazole does not appear to offer additional benefits over monotherapy with 5% natamycin for the management of fungal keratitis.

Adult↗

Comparison of topical itraconazole 1% with topical natamycin 5% for the treatment of filamentous fungal keratitis.

PURPOSE: To compare the clinical efficacy of itraconazole 1% eyedrops with a standard therapy regimen (natamycin 5% eyedrops) for topical monotherapy of fungal keratitis. METHODS: Patients presenting with suspected uniocular microbial keratitis over a period of 12 months (January to December 2002) underwent detailed clinical examination and microbiological investigation. One hundred consecutive patients with direct smear- and/or culture-proven fungal keratitis were enrolled in the study after obtaining informed consent. The ulcers were categorized as severe or nonsevere. The first 50 consecutive patients received primary therapy with topical natamycin hourly, and the next 50 consecutive patients received topical itraconazole hourly. The primary efficacy criteria were the physician's judgment of clinical success, cure rate, and the rate of treatment failure. RESULTS: The diagnosis of fungal keratitis was established by positive microscopy and culture findings in 88 patients and by positive microscopy alone in 12 patients. Species of Fusarium, Aspergillus, and Curvularia were the principal isolates. Thirty-six (72%) of 50 patients (28 of 37 with nonsevere keratitis and 8 of 13 with severe keratitis) showed a favorable response to primary natamycin therapy (mean duration, 20.5 days), while 30 (60%) of 150 patients (25 of 38 with nonsevere keratitis and 5 of 12 with severe keratitis) exhibited a favorable response to primary itraconazole therapy (mean duration, 23.1 days). In keratitis due to Fusarium spp, 19 (79%) of 24 patients showed a favorable response to natamycin, which was significantly greater than the 8 (44%) of 18 patients who showed a favorable response to itraconazole (P < 0.02). However, no such difference was evident in keratitis due to Aspergillus spp or Curvularia spp; in keratitis due to Aspergillus spp, favorable responses were noted in 6 (54.5%) of 11 patients receiving natamycin and 5 (50%) of 10 patients receiving itraconazole, while in keratitis due to Curvurlaria spp, such responses occurred in both patients receiving natamycin and in 8 (89%) of 9 patients receiving itraconazole. Both antifungal formulations were generally well tolerated with no obvious adverse effects. CONCLUSIONS: Topical natamycin should continue to be considered as the treatment of choice for filamentous fungal keratitis; when natamycin is unavailable, topical itraconazole therapy could be used, particularly if the infections are due to Aspergillus or Curvularia spp.

Administration, Topical↗

Formation of natamycin:cyclodextrin inclusion complexes and their characterization.

Natamycin is a broad spectrum antimycotic with very low water solubility, which is used to extend the shelf life of shredded cheese products. beta-Cyclodextrin (beta-CD), hydroxypropyl beta-cyclodextrin (HP beta-CD), and gamma-cyclodextrin (gamma-CD) were found to form inclusion complexes with natamycin in aqueous solution. The increase in solubility of natamycin with added beta-CD was observed to be linear (type A(L) phase solubility diagram). The 1:1 stability constant of natamycin:beta-CD complex was estimated from its phase solubility diagram to be 1010 M(-1). The phase solubility diagrams of both gamma-CD and HP beta-CD exhibited negative deviation from linearity (type A(N) diagram) and, therefore, did not allow the estimation of binding constants. The water solubility of natamycin was increased 16-fold, 73-fold, and 152-fold with beta-CD, gamma-CD, and HP beta-CD, respectively. The natamycin:CD inclusion complexes resulted in in vitro antifungal activity nearly equivalent to that of natamycin in its free state.

Antifungal Agents↗

[The spectrophotometric determination of natamycin in cheese].

Derivative spectroscopy was used for quantitative determination of natamycin in cheese. When measuring a methanolic cheese extract against methanol, the second derivative of the UV-spectrum is measured between 340 and 290 nm. The natamycin concentration can be determined by measuring the vertical distance between the minimum at 318 nm and the maximum at 311 nm. Under these conditions the detection limit of natamycin in a pure methanolic solution lies at 20 ng/ml, in cheese extracts at 150 ng/ml. The latter corresponds to a natamycin concentration of 2.5 ppm in the case of a 3 g test sample or 0.03 mg/dm2 in the case of a 25 cm2 cheese surface. The introduction of derivative spectroscopy makes it possible to reduce the interference of cheese substances in the photometric measurements and to increase the sensitivity and selectivity of the detection process. Besides the advantage that work and expenses are reduced - as no pimaricin-free sample has to be extracted from the interior of the cheese - it is also possible to determine natamycin photometrically in cheese, in which it is distributed homogeneously.

Cheese↗

A case-control teratological study of vaginal natamycin treatment during pregnancy.

The aim of this study was to investigate the teratogenicity of vaginal natamycin treatment during pregnancy, because the data of human epidemiological studies have not been published. Pair analysis of cases with congenital abnormalities and matched healthy controls was carried out. The population-based data set of the Hungarian Case-Control Surveillance of Congenital Abnormalities between 1980 and 1996 included as total, 38,151 pregnant women who delivered newborn infants without any defects (control group) and 22,843 pregnant women who had fetuses or newborns with congenital abnormalities. 62 (0.27%) and 98 (0.26%) pregnant women were treated with the natamycin in the case and control groups, respectively (crude OR 1.1 with 95% CI: 0.8-1.5). A teratogenic potential of vaginal natamycin treatment during the second and third months of pregnancy, the critical period of most major congenital abnormalities, was not indicated in the case-control pair analysis (adjusted OR 0.9 with 95% CI: 0.4-1.8). A somewhat higher mean birth weight (72 g) was found in control newborn infants born to mothers with natamycin treatment compared with the data of control newborn infants without this treatment (adjusted P=0.01), though mean gestational age was shorter. The conclusion of this study is that the treatment with vaginal natamycin during pregnancy presents no detectable teratogenic risk to the fetus.

Abnormalities, Drug-Induced↗

Natamycin as a selective antifungal agent in media for growth of Legionella spp.

The growth of 18 different Legionella sp. strains and 76 different yeast isolates was tested on buffered charcoal yeast extract medium supplemented with alpha-ketoglutarate (BCYE alpha medium) and with natamycin, an antifungal agent. Bacterial growth was no different on BCYE alpha medium made with or without natamycin, whereas complete inhibition of yeasts occurred in BCYE alpha medium containing 200 to 500 micrograms of natamycin per ml. Selective BCYE alpha media made with natamycin rather than anisomycin had no (formulation with vancomycin, polymyxin B, and agar) or little (formulation with cefamandole, polymyxin B, and agar) inhibitory effect on the growth of 14 different Legionella sp. bacteria. Natamycin is an inexpensive alternative to anisomycin in the formulation of selective BCYE alpha media.

Animals↗

In vitro fungistatic and fungicidal activities of silver sulfadiazine and natamycin on pathogenic fungi isolated from horses with keratomycosis.

OBJECTIVE: To evaluate the in vitro antifungal properties of silver sulfadiazine (SSD) and natamycin against filamentous fungi isolated from eyes of horses with keratomycosis. SAMPLE POPULATION: Filamentous fungal isolates obtained from eyes of keratomycosis-affected horses. PROCEDURES: Fungal culture of ocular samples yielded 6 Fusarium spp; 7 Aspergillus spp; and 1 isolate each of Curvularia, Scopulariopsis, Penicillium, and Chrysosporium. For each fungal isolate, minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of SSD and natamycin were determined. RESULTS: For all 17 fungal isolates, SSD MIC distribution ranged from < or = 1 to > 64 microg/mL; MIC50 and MIC90 (MICs at which 50% and 90% of organisms were inhibited) were 4 and 32 microg/mL, respectively. The SSD MFC distribution for all isolates was < or = 1 to > 64 microg/mL; MFC50 and MFC90 (MFCs at which 50% and 90% of organisms were killed) were 8 and > 64 microg/mL, respectively. For all fungal isolates, natamycin MIC distribution ranged from 256 to > 1,000 microg/mL; MIC50 and MIC90 were 512 and > 1,000 microg/mL, respectively. The natamycin MFC distribution for all isolates ranged from 512 to > 1,000 microg/mL; MFC(50) and MFC(90) were each > 1,000 microg/mL. CONCLUSIONS AND CLINICAL RELEVANCE: These in vitro data suggest that SSD is fungicidal against the fungal isolates that were obtained from eyes of horses with keratomycosis and that natamycin is fungicidal against some of the isolates at the drug concentrations evaluated. Silver sulfadiazine may be a therapeutic option for equine keratomycosis.

Animals↗

New high-molecular decomposition products of natamycin (pimaricin) with intact lactone-ring.

Mild acid treatment of natamycin (IV) results in biologically inactive aponatamycin (VI), an amphoteric substance with some natamycin-like chemical and physical properties. Aponatamycin contains one natamycin- and one natamycinolide-moiety. More drastic acid degradation of natamycin eliminates the aminosugar under formation of the dimer (VII) of the hypothetical aglycone of natamycin, natamycinolide (V) as well as a non-ionic compound, the dimer of the 12-decarboxy-11-anhydro analogue of natamycinolide.

Chemical Phenomena↗

Influence of inoculum type and cultivation conditions on natamycin production by Streptomyces natalensis.

This study demonstrates the effect of cultivation conditions on the production of natamycin. Of these conditions, the effect of oxygen limitation and type of inoculum were extensively investigated. Increasing the shaking speed and decreasing the medium volume improved both the volumetric and specific natamycin production. Also, decreasing the dissolved oxygen level in the cultivation medium through the addition of soluble biopolymer (alginate) resulted in a significant decrease in the natamycin yield without effect on the cell growth. On the other hand, spore inoculum yielded higher concentration of natamycin compared to the vegetative cells by about 40%. The maximal cell productivity based on biomass [Yp/x] of about 0.4 [g/g] was obtained by using shake flask of 50 ml working volume agitated at 200 rpm and the inoculum was in the form of spore 2 x 10(8) spores/ml. These results showed that the production process of natamycin is highly dependent on oxygen level in the cultivation medium and type of inoculum as well.

Culture Media↗

[Natamycin (pimaricin) in the treatment of experimental keratomycosis].

The efficacy of natamycin (pimaricin) was studied and compared with the standard amphotericin B, using a reproducible model of keratomycosis from Candida albicans in the rabbit. C. albicans DSM 70010 (2.5 X 10(5) cells) was injected into the corneal stroma of both eyes. All eyes developed a corneal ulcer without pretreatment with immunosuppressive agents. Forty-eight hours after inoculation, the animals were divided into five groups: I (10 eyes) and II (12 eyes) receiving natamycin drops, 1%; groups III (12 eyes) and IV (12 eyes) receiving natamycin, 2.5%; the control group (14 eyes) receiving 0.9% NaCl. For better penetration of the drug, the epithelium of groups I and III was removed every 3rd day. Half of the control group was debrided as well. In a further series, the penetration of natamycin into the cornea and aqueous humor was studied. There was no difference between the treated eyes and the control eyes concerning complications (descemetocele or perforation). It is concluded that natamycin (pimaricin) is inferior to amphotericin B and not effective in controlling experimental keratomycosis.

Animals↗

Spectrometric and liquid chromatographic determination of natamycin in cheese and cheese rind.

Methods for determining natamycin content of cheese rind and cheese are presented. Cheese and rind samples are extracted with methanol and the fat precipitated by cooling the sample solution in methanol-water at -15 to -20 degrees C for ca 1 h. Natamycin levels are measured by UV spectrometric detection at absorbance minimum 311 nm, maximum 317 nm, and at exactly 329 nm, or by LC separation over Lichrosorb RP-8 column with detection at 303 nm. For measuring low levels, a concentration step is provided. The method is applicable to natamycin in cheese rind and in the interior of the cheese. Detection limit is 0.5 mg/kg. The method is suitable for controlling a maximum tolerance of natamycin on the cheese rind, at a level of 1 mg/dm2, and for detecting migration of natamycin into the cheese.

Cheese↗

Natamycin as a fungicide in agar media.

Fungal inhibition in four commonly used agar media was improved by substituting natamycin (pimaricin) for cycloheximide. The recovery of bacteria was not affected by natamycin, whereas fungal contamination from a variety of samples was significantly suppressed. Furthermore, natamycin lacks the occupational health hazards of cycloheximide. Medium-dependent natamycin degradation occurred during the preparation and refrigerated storage of agar plates, but the addition of natamycin at 21.6 mug/ml resulted in effective residual activity.

Journal Article↗

Evaluation of a selective medium for Brucella isolation using natamycin.

AIMS: To select an anti-fungal agent to replace cycloheximide in the media used for isolation of Brucella. METHODS AND RESULTS: One potential agent, natamycin, was evaluated using 28 Brucella isolates, 18 yeasts and 14 fungi. The material for the evaluation included 37 bovine milk samples, six bovine vaginal swabs and 45 milk samples artificially infected with Brucella. The recovery of Brucella only from the artificially-inoculated milk samples increased with the use of the medium containing natamycin instead of cycloheximide, at the same time significantly inhibiting the growth of yeasts, fungi and other bacteria. The inclusion of either anti-fungal agent allowed growth of the 28 Brucella isolates and totally prevented the growth of all 18 yeasts and 13 of the 14 fungi. CONCLUSIONS: Based on the results it was concluded that natamycin would be a suitable alternative to cycloheximide. SIGNIFICANCE AND IMPACT OF THE STUDY: Cycloheximide has become unavailable worldwide and is currently an anti-fungal constituent of the medium often used for isolation of Brucella organisms. The use of natamycin as a replacement in the formulation did not inhibit growth of Brucella and was effective at eliminating most contaminants.

Animals↗

Results of a combination treatment with natamycin and butylscopolamine in cases of intestinal Candida colonization.

The findings described show that Candida species can be found in the feces of approximately half a population of nonselected test persons and in the mouths of approximately a third. Intestinal Candida colonization was found in most of these persons after one feces examination, and in practically all of them after a second examination. 10 d of therapy with 400 mg natamycin per day in sugar-coated tablet form and 40 mg natamycin in the form of tablets for sucking produced a negative fungus test for the feces in only 20% of the cases. Although a combination of this therapy with 3 x 10 mg butylscopolamine per day improved short-term results significantly, the long-term results were hardly influenced at all. Typifying results according to the Warnock method showed that we are dealing with recurrences in practically all cases and not with new infections. Minimal inhibition concentrations (MIC) of natamycin showed no marked changes as a consequence of the natamycin treatment.

Adult↗