Sabouraud Agar Plates Research Articles

Occupational asthma caused by exposure to neurospora in a plywood factory worker.

A 24 year old man developed severe asthma two years after starting to work in a plywood plant. Four years later the patient had to stop working because of the increasing severity of his asthma. Three months after leaving his job, the patient's asthma was greatly improved. His job consisted of placing plywood sheets into a drying machine. The plywood sheets had stayed outside in wet conditions for at least four to six weeks and were usually covered with moulds. Drying the plywood sheets changed the mould into a fine orange powder. Exposure to this in the laboratory induced an isolated immediate asthmatic reaction. The same reaction was seen when the patient was challenged with an extract of the mould powder at a 0.1% w/v concentration. Skin prick test with the mould extract induced a weal and flare reaction and IgE antibodies against the dry mould powder were identified. A control patient with the same degree of bronchial hyperreactivity did not have any asthmatic reaction when challenged with the same mould extract. Culture of the dry mould powder on Sabouraud agar plates grew pure Neurospora sp. This mould has not been previously reported as a cause of occupational asthma. The immunological mechanism is probably related to an IgE mediated mast cell allergy.

Studies on the Fungal Pathogen of Dutch Elm Disease

The fungal pathogen of the Dutch elm disease (DED), Ceratocystis ulmi (Buisman) C. Moreau, has eluded effective control since its introduction in the United States more than sixty years ago. Our studies on DED include establishing biological control agents against C. ulmi. In this report we describe the inhibitory action of the antibiotic polymyxin B on the causal agent of DED.In screening a number of antibiotics against C. ulmi, we observed that filter paper discs containing 300 units (U) of polymyxin B (Difco Laboratories) per disc, produced zones of inhibition to the fungus grown on potato dextrose agar or Sabouraud agar plates (100mm x 15mm), Fig. 1a. Total inhibition of fungal growth on a plate occurred when agar overlays containing fungus and antibiotic (polymyxin B sulfate, ICN Pharmaceuticals, Inc.) were poured on the underlying agar growth medium. The agar overlays consisted of the following: 4.5 ml of 0.7% agar, 0.5 ml of fungus (control plate); 4.0 ml of 0.7% agar, 0.5 ml of fungus, 0.5 ml of polymyxin B sulfate (77,700 U). Fig. 1, b and c, compares a control plate and polymyxin plate after seven days.

Lytic action of lysozyme on candida albicans

Yeast cells ofCandida albicans in lysozyme glucose solution were incubated in a 37° C water bath for 6 hours, spread on the surface of a Sabouraud's agar plate and incubated at 37° C for 18–24 hours. Scattered small colonies were seen on the agar surface compared with the thick full growth of the control culture incubated without lysozyme. Twenty-one strains of 6 standard Candida species of human isolation other thanCandida albicans; C. stellatoidea, C. tropicalis, C. pseudotropicalis, C. krusei, C. parapsillosis, C. guilliermondii, showed essentially the same results asCandida albicans. A constant quantity of lysozyme caused destruction of Candida cells to an equal degree, regardless of varied concentrations of glucose. Dilution of lysozyme greater than 100 times the original (5 mg/ml) showed the same degree of candicidal activity, however, was dependent on the presence of minute amounts of glucose. The presence of NaCl prevented the lysis of Candida by lysozyme in various solutions. Candida cells with lysozyme in glucose solution was incubated for 6 hours in a 37° C water bath. Microscopic observations revealed drastic changes in cell morphology. Most of the cells were swollen, degenerated and some completely destroyed. The gram-positive characteristics of Candida cells changed to gram-negative. The combined activity of lysozyme with complement and antibody may play an important role in the protection against Candidiasis in vivo.

Rapid diagnosis of Candida albicans.

The inhibitory action of an antibiotic isolated fromB. subtilis is studied onC. albicans, C. clausenii, C. langeronii, C. stellatoidea, andC. visvanathii, as a possible means forC. albicans rapid identification. Growth inhibition ofC. albicans by the antibiotic was observed when the yeast was preincubated on malt-agar slants, at 30° C, during 24 hours, and tested afterwards for antibiosis on Sabouraud-agar plates. No growth inhibition could be detected withC. clausenii, C. langeronii, C. stellatoidea, andC. viswanathii, under the same experimental conditions.

Isolation, Identification and Susceptibility Profile of Rhodotorula Species Isolated From Two Educational Hospitals in Ahvaz

Background: Rhodotorula species are common airborne contaminant fungi and are also considered as normal inhabitants of the skin, lungs, urine and feces in humans. The most common species of Rhodotorula include; Rhodotorula. mucilaginosa, R. glutinis and R. minuta. Rhodotorula species are considered as an important agent for invasive infection among immunocompromised patients. Both amphotericin B and flucytosine were active against Rhodotorulain vitro, whereas fluconazole was inactive. Objectives: In the present study Rhodotorula species were isolated from two educational hospitals in Ahvaz and their sensitivity profiles were evaluated against several antifungal agents including; amphotericin B, nystatin, miconazole, clotrimazole, fluconazole and terbinafine. Materials and Methods: Six hundred samples were collected from different areas of two educational hospitals of Ahvaz. Wet and sterile cotton swabs were drawn on the studied surfaces and inoculated on Sabouraud agar plates containing chloramphenicol. All culture media were incubated at room temperatures for one week. During incubation times, all red-orange yeast colonies were selected and their morphology was confirmed by a microscopic examination. Yeasts were identified by a commercial system ID 32 C. In vitro susceptibility testing was performed by the disc diffusion method. Results: In the present study 72 strains of Rhodotorula were recovered from two educational hospitals of Ahvaz. R. glutinis (86.1%) was the most common species among the isolates, followed by R. mucilaginosa (6.9%), R. minuta (4.2%) and Rhodotorula species (2.8%). Most of the isolated yeasts were recovered from cardiology, nephrology and urology wards. Resistance to amphotericin B was found in 5.8% of isolates whereas 52.2% and 42.0% of isolates were dose dependent and sensitive to drugs, respectively. Fluconazole exhibited no activity in vitro against all strains of Rhodotorula. Resistance to terbinafine was found in 37.7% of isolates, whereas only 26.1% of the tested isolates were sensitive and the rest were dose dependent. Conclusions: In conclusion we can state that Rhodotorula have considerable distribution in critical wards and could be regarded as important invasive mycosis causative agents. In addition all tested antifungal agents, except fluconazole, are effective against Rhodotorula species in vitro.

Preliminary survey of fungistatic properties of marine algae.

Welch, Ann Marie (U. S. Veterans Administration Hospital, Durham, N. C.). Preliminary survey of fungistatic properties of marine algae. J. Bacteriol. 83:97-99. 1962-Homogenized preparations of 35 marine algae were tested for inhibitory activity against 6 pathogenic or opportunistically pathogenic fungi with saturated filter-paper discs on seeded Sabouraud agar plates; 11 of these preparations produced wide zones of inhibition against 1 or more test organisms, and at least 4 of the 11 are considered to be worthy of further study. The results indicated that further search should be made for antifungal substances from marine algae.

STUDY ON ANTI-CANDIDA ACTION OF A STRAIN OF BACILLUS SUBTILIS

In the course of the study to see if candidaphage could be isolated by spotmethod using candidas which were isolated from sputums of consumptives as the indicators and faeces of the same patients as the phage materials, a phenomenon that a saprophyte at the spot had been dissolving the surrounding candida colonies was observed. The saprophyte was then isolated, identified and its anticandida action has been studied.Identification of the saprophyte: The saprophyte was identified as Bacillus subtilis according to Bergey's a Manual of Determinative Bacteriology (Seventh Edition). The Bacillus subtilis is given a tentative name of Bacillus subtilis var . N T strain.The properties of the Bacillus subtilis are as follows:Gram positive, bacillus, length 0.9 to 1.8 microns (Fig. 1), spore 0.6 to 0.9 microns, ellipsoidal, middle-present, thin-walled, encapsulated, inflagellated.Broth: Good clear growth with heavy, tough pellicle. Sabouraud agar plate: Good growth forming heavy, grey, slightly moist, slimy, spreading and rough colonies (Fig. 2).Catalase reaction: Positive.Potato: Good growth, the colonies are small, grey, keenly fringed serrated and adherent and then the colonies conglutinate one another map-like and turn brown in the process of culture.Milk: Not coagulated.Gelatin stab: Liquefaction craterif orm to stratiform.Glycerin stab: Good growth, pink zone under the surface is observed.Voges-Proskauer reaction: Positive.Acid but no gas (by means of Barsiekow's peptone water) from arabinose, xylose, glucose, sucrose and mannitol. No acid from lactose.Optimum pH of Sabouraud broth culture is 5.3 to 7.4.Optimum growth temperature is 37°C.Conditions in which the bacillus produces anti-candida substances, extraction method of anti-candida substances, general properties, anti-candida and anti-bacterial spectra, test of virulence and animal experiment of the extracted substances are mentioned below.