Athlete's foot caused by pseudomonas aeruginosa

An enzymatically active pigment-producing clinical isolate of Pseudomonas aeruginosa was found to produce a diffusible antifungal product that was shown to be inhibitory to the growth of several dermatophytes, specifically, Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum gypseum, and Microsporum audouini. In this study, Trichophyton rubrum was used as the test organism. The antifungal product was partially purified by Sephadex column chromatography and was found to be stable at 5 degrees, 25 degrees, and 37 degrees C. Several investigators have alluded to the fact that as asymptomatic cases of dermatophytosis simplex progress to symptomatic dermatophytosis complex, the bacterial profile changes from a gram-positive bacterial ecosystem to a gram-negative bacterial over-growth. The primary event in the pathogenesis of interdigital athlete's foot is the invasion of the horny layer by dermatophytes. This presents as a mild to moderate scaly lesion and is asymptomatic. As a result of predisposing factors, such as hyperhidrosis, occlusion by tight shoes, minute abrasions due to friction, and fungal-infected skin surfaces, dynamic overgrowth of opportunistic gram-negative bacilli prevails. As the gram-negative population increases, the recovery of dermatophytes dramatically diminishes, until a point is reached when no dermatophytes can be recovered from clinically symptomatic tinea pedis. Pseudomonas aeruginosa is inhibiting its fungal competitor Trichophyton rubrum by producing a diffusible antifungal agent into the infectious environment of the intertriginous foot lesion. Clinically, the patient is diagnosed as having tinea pedis; laboratory culture for fungus and KOH are negative, and what was a paradox just a few years ago can currently be identified and treated appropriately as gram-negative athlete's foot.

Evaluation of trichophyton agars for identification of Trichophyton soudanense

Studies of three monoconidial subcultures of each of 10 isolates of Trichophyton soudanense on seven trichophyton agars revealed variations in growth among the subcultures of each isolate and among the isolates themselves on six agars. In contrast, greater consistency and generally good to excellent growth were noted with all isolates on trichophyton agar 1 (basal medium). These results are contrary to those found with other Trichophyton species and suggest that growth on the trichophyton agars is not a suitable test for the identification of T. soudanense.

Restoration of Trichophyton mentagrophytes growth in medium depleted of metals by chelation: importance of iron

The present study examined the requirement of Trichophyton mentagrophytes ATCC-18748 for iron. Nutrient broth depleted of iron by the chelating cation exchange resin Chelex-100 did not support the growth of T. mentagrophytes beyond germ tube formation. The soluble chelate of iron, ferric ammonium citrate, restored the capacity of the chelated medium to support fungal growth in proportion to the amount of iron added. Ferric chloride, which rapidly becomes insoluble at neutral pH, was not effective in the medium. The soluble salts of cobalt, chromium, copper, manganese, nickel, and zinc individually did not replace the requirement for iron. A method for defining the iron requirement based upon utilization of iron from ferric ammonium citrate is described. These data indicate that the growth of T. mentagrophytes ATCC-18748 is iron-dependent, which is consistent with the hypothesis that serum transferrin inhibits dermatophyte growth by the mechanism of iron deprivation.

Vaccination procedures and the infectivity of dermatophyte lesions

By means of an experimental guinea pig model, the immunogenicities of a live spore vaccine, a killed hyphal cell wall vaccine and a soluble cytoplasmic extract vaccine of Trichophyton mentagrophytes var. erinacei were compared, and their modifying influence on the infectivity and duration of experimental dermatophyte lesions examined. Of the three vaccines, the live-spore one was the most effective and closely simulated the type of immunity which develops following a natural infection. Lesions produced in cell wall vaccinated animals revealed significantly less infectivity and were reduced in duration as compared with lesions in unvaccinated animals. The cytoplasmic extract vaccine had no beneficial effect on the course of experimental infection; indeed it seemed to increase the infectivity of lesions. Acquired resistance to reinfection in a pregnant guinea pig was not passed on to the offspring. Significant levels (titer of greater than or equal to 1:16) of antibody were detected in the sera of all infected and vaccinated animals using an indirect fluorescent antibody technique and germling antigens. Using counterimmunoelectrophoresis, precipitating antibodies were detectable in the sera of all seven animals vaccinated with the cell wall or cytoplasmic extract, in one (20%) of the control animals after reinfection, and none of the four animals injected subcutaneously with the live spore vaccine. Thus no correlation between antibody titer and the severity and duration of lesions was observed. These results endorse the growing hypothesis that cell mediated immunity is of prime importance in protection again dermatophyte invasion and suggests that prophylactic vaccination procedures are worthy of further evaluation in lower animals.

The effect of bifonazole on the structure of Trichophyton

The effect of a new azole antimycotic, 1-[(4-biphenylyl)-phenylmethyl]-1H-imidazole (bifonazole, Bay h 4502, Mycospor) on the morphology of hyphae of Trichophyton mentagrophytes grown in a liquid medium was studied by high-resolution scanning electron microscopy. With bifonazole at concentrations ranging from 1 to 10 ng/ml that were much lower than the MIC value of the drug for this test strain (630 ng/ml), the hyphal growth was significantly inhibited and several morphological changes of the hyphae were produced. They were characterized by: (1) development of wavy or curled hyphae, (2) occasional formation of swollen cells often arranging in chain; (3) partial exfoliation of hyphal walls; and (4) excretion of fibrillar materials. These morphological changes of the hyphae became more prominent with increasing drug concentrations up to 200 ng/ml, and many hyphae were collapsed and distorted. These results strongly suggest that subinhibitory concentrations of bifonazole profoundly affected the normal growth and induced degenerative changes of the hyphae of T. mentagrophytes probably by damaging the cell membrane.

Factors affecting griseofulvin susceptibility testing of Trichophyton rubrum in microcultures

A microculture broth assay system for griseofulvin susceptibility testing of Trichophyton rubrum was further characterized. The effects of mass and number of colony-forming units of a fragmented mycelial inoculum, 5- or 8-day incubation periods, 25 or 32 degrees C incubation temperatures, and the solvents used to dissolve griseofulvin on the minimal inhibitory concentration (MIC) of griseofulvin were determined. An inoculum density with an absorbance of 0.600 at 450 nm ensured successful inoculation of all microcultures. Reduction of the inoculum mass to an absorbance of 0.200 lowered the number of colony-forming units in the inoculum by 60 to 80%. This decreased the efficiency of inoculation but did not alter the resulting MIC. There was no correlation between MIC and the number of colony-forming units used to initiate growth. Neither incubation temperature nor the length of incubation affected the MIC. The use of either acetone or ethanol to solubilize griseofulvin likewise had no effect on the MIC. The mean reproducibility of the MICs determined with the microculture method was 96%.

The "hair root invasion test", a semi-quantitative method for experimental evaluation of antimycotics in guinea-pigs

The hair root invasion test is a new method for preclinical evaluation of the antimycotic efficacy of chemical compounds in vivo based on their antifungal activity against dermatophytes located at hair roots in the depth of the hair follicles of guinea-pigs. The test design allows for semi-quantitative assessment of the invasion density of the hair follicles in mycotic foci of treated and untreated animals. Conditions that must be met in order to yield satisfactory results are discussed and test results from standard antimycotics are presented.

Fungistatic capacity of sera from guinea pigs injected with various iron solutions: differences between Trichophyton mentagrophytes and Rhizopus oryzae

The fungistatic capacity and serum ion levels (SI) of guinea pigs given subcutaneous injections of various iron solutions were examined. The administration of 2.0 ml of 0.1 M ferric ammonium sulfate, ferric sulfate, or ferric chloride subcutaneously had no significant effect on the SI 3 h after administration, whereas ferric ammonium citrate, ferric citrate, or ferrous sulfate elevated the SI to 50 to 140 times that necessary to saturate the unbound transferrin in normal sera. The sera from 11 of 15 guinea pigs with an elevated SI remained fungistatic for Trichophyton mentagrophytes, whereas 3 of 15 guinea pigs with an elevated SI remained fungistatic for Rhizopus oryzae. The sera from normal guinea pigs were consistently fungistatic for Rhizopus oryzae. The sera from normal guinea pigs were consistently fungistatic for both T. mentagrophytes and R. oryzae. These data suggest that subcutaneous administration of certain iron compounds can significantly elevate the SI without completely abolishing the fungistatic capacity of the serum.

Antifungal activity of dermatological shampoos

The effect of several "medicated" shampoos on the growth of a variety of fungi was determined. Shampoos with as low as 0.5% coal tar were inhibitory to all strains, 2.5% selenium sulfide and 1 and 2% zinc pyrithione were significantly more inhibitory. Since these shampoos have substantivity for the human scalp, they may be useful as adjunctive therapy to griseofulvin in the treatment of scalp infections and minimize the risk of spread of viable spores to others in the environment.

Laboratory alert: clues to the identification of dermatophytes as the etiologic agents of subcutaneous abscesses

Trichophyton mentagrophytes was isolated on blood agar and in thioglycollate broth after prolonged incubations of four and seven days, respectively, of a routine bacterial culture taken from a subcutaneous abscess on the inner thigh of a 24 year old woman. The lesions had been present on both thighs for six months before correct diagnosis and treatment. Attention is called to the importance of clinical history to the alert microbiologist in determining the correct diagnosis of such lesions when the original bacterial culture reveals no growth after 48 hours.

Utilization of standard laboratory methods in the laboratory diagnosis of problem dermatophytes

The identification of certain dermatophytes may be simplified by using biochemical tests such as urease, nutritional requirements (with commercially available media), and the in-vitro hair penetration test. No study that combines these tests in a diagnostic scheme for identification of the common dermatophytes has been published. one to 20 isolates each of 29 species of dermatophytes (one Epidermophyton floccosum, 10 Microsporum species, and 18 Trichophyton species) were used. They were grown on Christensen's urea agar and the seven nutritional media for the differentiation of the Trichophyton species; the in-vitro hair penetration test was performed in duplicate. Patterns were developed that have been tested and proven to be useful for more than 22 months. In addition, the Microsporum species were all grown on polished rice, and color and sporulation were recorded. All dermatophytes in this study were grown on either Mycosel agar or 2% malt extract agar, and on modified potato dextrose agar and modified Sabouraud agar. Macroscopic and microscopic examinations were made to determine qualitatively the amounts of growth and sporulation on each medium.

Effect of moderately elevated temperatures on dermatophyte survival in clinical and laboratory-infected specimens

The effect of increased temperature during transportation of clinical dermatophyte specimens was investigated. Recovery rates from untransported specimens cultured at dermatologists' offices and from duplicate transported specimens were compared. During the months of hot weather specimens could be exposed intermittently to temperatures as high as 60 degrees C during transportation from Tucson area clinics to the University laboratory. The rates of recovery from known positive specimens were found not to be significantly different at these places regardless whether specimens were transported during the hot months or cooler months of the year. In a controlled experimental approach to the effect of this elevated temperature on clinical specimens weighed amounts of skin scales collected from guinea pigs artificially infected with Trichophyton mentagrophytes were exposed to 60 degrees C for up to four hours and then digested with 0.5% (:300) trypsin for one hour. Analysis of plate counts done from the digestion mixture showed no significant difference between counts obtained from specimens exposed to elevated temperature and unexposed controls.

Comparison of gentamicin with other antibacterials and variation of incubation temperature on growth of trichophyton mentagrophytes from skin scales

Neutral (Emmons modification) Sabouraud medium, Dermatophyte Test Medium and Littman oxgall agar, with substitutions in type of antibacterial antibiotic, were quantitatively evaluated by colony counts for ability to support growth when suspensions of trypsintreated guinea pig skin scales, infected with Trichophyton mentagrophytes, were used as inocula. Both liquid and powder form of gentamicin sulfate were used separately in place of other routinely used antibacterial antibiotics. Also evaluated were three isolation temperatures. No differences in ability to support growth were noted among media. No difference was noted between the two forms of gentamicin. No data were available on the antibacterial activities of the antibiotics because no bacterial growth was produced on any of the media. Room temperature (24 degrees-26 degrees C), 30 degrees C and 37 degrees C were found to support growth similarly as primary isolation temperatures for this fungus.

Effect of storage temperature on viability of Trichophyton mentagrophytes in infected guinea pig skin scales

The effect of storage temperature on the viability of Trichophyton mentagrophytes in infected guinea pig skin scales was quantitatively evaluated for 182 days. Infected skin scales were stored, while protected from light, in glass containers with desiccant at four temperatures and sampled after saline treatment at various time intervals. No decrease in viability was observed for storage at 4 degrees C, room temperature, or 30 degrees C. Storage at 37 degrees C resulted in a significant loss in viability.