Microsporum canis infections in children: results of a new oral antifungal therapy

Current use of anti-infectives in dermatology

Dermatologic diseases encompass a broad category of pathologic situations. Infection remains a significant aspect of the pathology faced in patient encounters, and it is natural to expect that anti-infectives play a major element in the armamentarium utilized by dermatologists. Aside from the treatment of the classic bacterial and fungal infections, there are now new uses for antiviral agents to help suppress recurrent disease, such as herpes simplex. There is also the novel approach of using anti-infectives, or agents that have been thought to have antimicrobial activity, to treat inflammatory diseases. This review describes anti-infectives, beginning with common antibiotics used to treat bacterial infections. The discussion will then cover the current use of antivirals. Finally, the description of antifungals will be separated, starting with the oral agents and ending with the topical antimycotics. The use of anti-infectives in tropical dermatology has been purposefully left out, and perhaps should be the subject of a separate review. Cutaneous bacterial infections consist chiefly of those microorganisms that colonize the skin, such as species of staphylococcus and streptococcus. Propionibacterium acnes and certain other anaerobes can be involved in folliculitis, pyodermas and in chronic conditions such as hidradenitis suppurativa.

Efficacy and safety of itraconazole use in children

Current dosing regimens for itraconazole are effective, safe, and versatile for use in superficial fungal infections in children, particularly tinea capitis. Good efficacy rates have been noted in both Trichophyton and Microsporum tinea capitis infections. Itraconazole has a high affinity for keratin, and accumulates to high levels at the site of superficial fungal infections. A pulse regimen may be chosen over continuous dosing, because the accumulation persists after dosing of itraconazole has been stopped. An oral solution of itraconazole is available, and may be more convenient for children who cannot swallow capsules. The oral solution also produces good rates of efficacy, but may be associated with a somewhat higher potential for gastrointestinal adverse events than the capsules. The range of adverse events noted with itraconazole capsules or oral solution use in children is similar to the range in adults. Events are generally mild and transient. Attention must be taken to note any medications that the child is using, because itraconazole is associated with a range of potential drug interactions. This safety of use, in combination with itraconazole's wide antifungal spectrum and pharmacokinetic properties, which allow for shorter dosing regimens, may make itraconazole a suitable alternative to griseofulvin for pediatric superficial fungal infections.

Tinea corporis, tinea cruris, tinea nigra, and piedra

Tinea infections are among the most common dermatologic conditions throughout the world. To avoid a misdiagnosis, identification of dermatophyte infections requires both a fungal culture on Sabouraud's agar media, and a light microscopic mycologic examination from skin scrapings. Topical antifungals may be sufficient for treatment of tinea corporis and cruris and tinea nigra, and the shaving of hair infected by piedra may also be beneficial. Systemic therapy, however, may be required when the infected areas are large, macerated with a secondary infection, or in immunocompromised individuals. Preventative measures of tinea infections include practicing good personal hygiene; keeping the skin dry and cool at all times; and avoiding sharing towels, clothing, or hair accessories with infected individuals.

Itraconazole in the treatment of tinea capitis in children. Case reports with long-term follow-up evaluation. Review of the literature

Although griseofulvin is considered the standard treatment of tinea capitis in children, alternatives are being investigated. Our purpose was to determine the efficacy of itraconazole for kerion and noninflammatory tinea capitis. An open label study was performed on five patients. It was planned to treat them with itraconazole until they were mycologically and clinically cured. A 28-112-day course of 100 mg itraconazole daily, combined with a topical antifungal treatment resulted in clinical and mycological cure in all children. One child stopped taking itraconazole after 28 days, before it was clinically cured, because of nausea. Nevertheless, this child also achieved clinical and mycological cure. No other side-effects were reported. In long-term follow-up evaluation of between 2 and 3.5 years no recurrence or reinfection was observed. There was complete regrowth of hair, even after kerion. These findings and the review of the literature suggest that itraconazole offers an alternative to griseofulvin for the treatment of tinea capitis in children, although it is more expensive and not approved by German state authorities for this indication.

Itraconazole is effective in the treatment of tinea capitis caused by Microsporum canis

Tinea capitis is a relatively common superficial fungal infection in children which requires oral antifungal therapy. In a prospective, open study over 24 weeks, itraconazole 5 mg/kg/day, given as capsules or as an oral suspension for a period of 2-12 weeks, was used to treat children 1-12 years of age who had M. canis tinea capitis. Children with mycologic evidence of M. canis tinea capitis were entered into the study and asked to return at week 2 and then every 2 weeks thereafter until cured, with a maximum of 12 weeks of active treatment. At each visit the scalp was sampled and the material processed for light microscopy and culture examination. An extra 2 weeks of itraconazole was prescribed if the mycology from the sample obtained on the previous visit indicated that there was still presence of the organism. Patients were administered either 2, 4, 6, 8, 10, or 12 weeks of treatment. The final follow-up visit was at 12 weeks from the cessation of drug therapy. Laboratory blood testing was performed only if indicated by history, examination, or the development of side effects. There were 107 patients (49 boys, 58 girls; mean +/- standard error =5.6 +/- 0.2 years). Thirteen of the 107 children were given the oral suspension. At week 12 from the cessation of treatment there was complete (clinical and mycologic) cure in all 107 children. Increasing age of the patient correlated significantly with the length of itraconazole capsule therapy (p=0.03). The duration of itraconazole treatment also correlated significantly with the severity of tinea capitis at baseline (p=0.02). Adverse effects were observed in 5 children receiving itraconazole capsules (n=94). These were regarded as being possibly or probably due to the drug in two children (mild transient stomach ache in one and moderate diarrhea in one). The child with diarrhea stopped therapy at week 4 with complete resolution of symptoms. One of 13 children receiving the oral suspension had mild, transient diarrhea. There were no drop-outs in this group. Laboratory testing was not required in any patient. Compliance was very good in the patient group. Itraconazole 5 mg/kg/day given either as a capsule or an oral suspension for 4-8 weeks is effective and safe in the treatment of tinea capitis caused by M. canis.

Therapeutic options for the treatment of tinea capitis caused by Trichophyton species: griseofulvin versus the new oral antifungal agents, terbinafine, itraconazole, and fluconazole

Tinea capitis is a relatively common fungal infection of childhood. Griseofulvin has been the mainstay of management. However, newer oral antifungal agents are being used more frequently. A multicenter, prospective, randomized, single-blinded, non-industry-sponsored study was conducted in centers in Canada and South Africa to determine the relative efficacy and safety of griseofulvin, terbinafine, itraconazole, and fluconazole in the treatment of tinea capitis caused by Trichophyton species. The regimens for treating tinea capitis were griseofulvin microsize 20 mg/kg/day x 6 weeks, terbinafine [> 40 kg, one 250 mg tablet; 20-40 kg, 125 mg (half of a 250 mg tablet); < 20 kg, 62.5 mg (one-quarter of a 250 mg tablet)] x 2-3 weeks, itraconazole 5 mg/kg/day x 2-3 weeks, and fluconazole 6 mg/kg/day x 2-3 weeks. Patients were asked to return at weeks 4, 8, and 12 from the start of the study. Griseofulvin was administered for 6 weeks and the final evaluation was at week 12. Terbinafine, itraconazole, and fluconazole were administered for 2 weeks and the patient evaluated 4 weeks from the start of therapy. At this time, if clinically indicated, one extra week of therapy was given. There were 200 patients randomized to four treatment groups (50 in each group). At the final evaluation at week 12, the number of evaluable patients were griseofulvin, 46; terbinafine, 48; itraconazole, 46; and fluconazole, 46. Patients who discontinued therapy or were lost to follow-up were griseofulvin, 1/3; itraconazole, 0/4; terbinafine, 0/4; and fluconazole, 0/4. The causative organisms were Trichophyton tonsurans and T. violaceum species. Patients were regarded as effectively treated at week 12 if there was mycologic cure and either clinical cure or only a few residual symptoms. Effective treatment was recorded in, intention to treat, griseofulvin (46 of 50, 92.0%), terbinafine (47 of 50, 94.0%), itraconazole (43 of 50, 86.0%), and fluconazole (42 of 50, 84.0%) (p=0.33). Adverse effects were reported only in the griseofulvin group (gastrointestinal effects in six patients). Discontinuation from therapy due to adverse effects occurred only in the griseofulvin group (nausea in one patient). For the treatment of tinea capitis caused by the Trichophyton species, in this study, griseofulvin given for 6 weeks is similar in efficacy to terbinafine, itraconazole, and fluconazole given for 2-3 weeks. Each of the agents has a favorable adverse-effects profile.

Comparison of two hard keratinous substrates submitted to the action of a keratinase using an experimental design

The influence of temperature, pH, keratinase concentration, substrate concentration and incubation time on the soluble proteins released by a new keratinase from Doratomyces microsporus was studied with a second-order experimental design. Only 15 or 18 spectrophotometric analyses were required to determine the optimal experimental conditions for this keratinase on nail and hoof. This study was carried out by measuring, according to Smith's method, the concentration of soluble proteins released by the enzyme on two substrates: nails and sheep hooves. Results give optimum conditions for the keratinase to release the soluble proteins: pH 8.2, keratinase concentration 0.14% (weight of keratinase lyophilisate/final volume) and substrate concentration 5% (weight of nail powder/final volume) for nails; temperature 38.8 degrees C, pH 9, substrate concentration 5% (weight of hoof powder/final volume) and a 5 h 55 min incubation time for hooves.

Optimizing the therapeutic approach in tinea capitis of childhood with itraconazole

BACKGROUND

Tinea capitis is the most common dermatophytosis of childhood with increasing incidence. Whereas griseofulvin is considered by many as the mainstay of treatment, newer oral antifungal agents, including fluconazole, itraconazole and terbinafine have demonstrated higher efficacy, resulting in shorter treatment durations.

OBJECTIVES

We aimed to determine the optimum regimen for the treatment of childhood tinea capitis with itraconazole.

METHODS

A mycological culture outcome-dependent combination of a 28-day continuous and facultative additional 14-day courses with itraconazole was used in 42 children (20 girls; 22 boys) aged 12-140 months (mean 66) with tinea capitis due to Microsporum canis (n = 26) and Trichophyton violaceum (n = 16). The drug was given orally according to the patients' body weight (50 mg daily for < 20 kg; 100 mg daily for > or = 20 kg) over 4 weeks. Direct microscopy and fungal culture as a parameter for efficacy were repeated 2 weeks after termination of treatment. Assessment of efficacy was based on the evaluation of results from light microscopy and culture at 8 weeks after initiation of treatment, and in the case of a further positive mycological culture at 14 and 20 weeks, respectively. A positive fungal culture at these times resulted in an additional course for 2 weeks with the initially chosen itraconazole dosage.

RESULTS

In 34 of 42 patients a single 4-week course of itraconazole resulted in a complete mycological cure of lesions as demonstrated by light microscopy and mycological culture. Four of 42 patients had to be treated by a second itraconazole course for 2 weeks, and four children received a third course of itraconazole for 2 weeks until all lesions showed negative direct microscopy and mycological culture. No abnormal haematological or biochemical results occurred. Apart from transient, completely reversible indigestion in two children, no side-effects were observed.

CONCLUSIONS

A culture-based 28-day continuous therapeutic regimen plus facultative cultural outcome-dependent additional 14-day courses of a body weight-adapted dosage of itraconazole in tinea capitis due to M. canis and T. violaceum is discussed; this offers the advantage of an effective therapy with complete negative direct microscopy as well as negative cultural results, within a shorter active treatment period (cf. previous studies with continuous administration of itraconazole).

Tinea capitis

Tinea capitis is a common dermatophyte infection of the scalp in children. Dermatophytes are classified into three genera; tinea capitis is caused predominantly by Trichophyton or Microsporum species. On the basis of host preference and natural habitat, dermatophytes are also classified as anthropophilic, geophilic and zoophilic. The etiological agents of tinea capitis usually fall in the first and last categories. In North America, tinea capitis is now predominantly due to Trichophyton tonsurans. During the past 100 years the most common North American organism for tinea capitis was initially Microsporum canis followed later by M. audouinii. In other parts of the world the epidemiology varies. Tinea capitis is generally observed in children over the age of 6 years and before puberty, with African Americans being the most affected group. Clinical presentations are seborrheic-like scale, 'black dot' pattern, inflammatory tinea capitis with kerion and tiny pustules in the scalp. The clinical diagnosis should be confirmed by mycological examination. Wood's light examination was of value in diagnosing tinea capitis due to M. canis and M. audouinii; however, it is not helpful in T. tonsurans tinea capitis. Asymptomatic carriers may be a significant reservoir of infection and spread of spores may also involve inanimate objects. Carriers may benefit from shampooing their hair. Treatment of tinea capitis requires an oral antifungal agent. The data from the use of terbinafine, itraconazole and fluconazole are promising and suggest that these agents have an efficacy similar to griseofulvin while shortening the duration of therapy. Both griseofulvin and the newer antimycotics have a favorable adverse-effect profile and are associated with high compliance.

Tinea capitis in Siena, Italy. An 18-year survey

In the period 1980-1998, 181 cases of tinea capitis out of a total of 1480 cases of dermatophytosis were observed in Siena, Italy; 176 cases were children (mean age 6 years, range 45 days to 14 years; 91 boys, 85 girls) and the other five cases were postmenopausal women. Diagnosis was made on the basis of culture which was positive in 179 cases, and direct microscopic observation which was positive in 155 of 179 cases. In two cases, positive direct microscopic results were not confirmed by the culture. The most frequently isolated mycete was Microsporum canis (162 cases, 90.5%) and the main source of infection was the cat, which was often a healthy carrier. The second most frequent mycete was Trychophyton mentagrophytes. Trichophyton violaceum, a dermatophyte practically absent from our province since the 1960s, was isolated in five patients. All patients were successfully treated. One adult was treated with oral ketoconazole and the other four with oral itraconazole. The children were all treated with griseofulvin and topical antimycotics. Two children, observed in 1997-1998, who did not respond to griseofulvin, achieved clinical and mycological recovery with oral itraconazole.

Oral therapy of common superficial fungal infections of the skin

Although superficial fungal infections of the skin often respond to topical agents, systemic therapy is sometimes necessary. This article gives a review of the effectiveness of the oral antifungal agents fluconazole, itraconazole, and terbinafine in the treatment of pityriasis versicolor, tinea corporis/cruris, and tinea pedis. Four hundred milligrams fluconazole as a single dose and 200 mg itraconazole daily for 5 to 7 days were effective in the treatment of pityriasis versicolor; terbinafine taken orally appears to be ineffective in pityriasis versicolor. Tinea corporis and tinea cruris were effectively treated by 50 to 100 mg fluconazole daily or 150 mg once weekly for 2 to 3 weeks, by 100 mg itraconazole daily for 2 weeks or 200 mg daily for 7 days, and by 250 mg terbinafine daily for 1 to 2 weeks. Tinea pedis has been effectively treated with pulse doses of 150 mg fluconazole once weekly, with 100 mg itraconazole daily for 2 weeks or 400 mg daily for 1 week, and with 250 mg terbinafine daily for 2 weeks.

Tinea capitis: an overview with emphasis on management

Tinea capitis is perhaps the most common mycotic infection in children. In North America the epidemiology of tinea capitis has changed so that Trichophyton tonsurans now predominates over Micro-sporum audouinii. With this transition the utility of the Wood's light for diagnosis has been reduced since T. tonsurans infection is Wood's light negative. Griseofulvin has been the mainstay of therapy for the last 40 years. The newer antifungal agents-itraconazole, terbinafine, and fluconazole-appear to be effective and safe for the treatment of tinea capitis. When tinea capitis is due to T. tonsurans or other endothrix species the following regimens have been used: itraconazole continuous regimen (5 mg/kg/day for 4 weeks), itraconazole pulse regimen with capsules (5 mg/kg/day for 1 week plus 1-3 pulses 3 weeks apart), and itraconazole pulse regimen with oral solution (3 mg/kg/day for 1 week plus 1-3 pulses 3 weeks apart). With terbinafine tablets the continuous regimen (>40 kg body weight, 250 mg/day; 20-40 kg, 125 mg/day; and <20 kg, 125 mg/day) is given for 2 to 4 weeks. Fluconazole tablets or oral suspension (6 mg/kg/day) were administered for 20 days in one trial. Another possibility may be 6 mg/kg/day for 2 weeks and evaluating the scalp 4 weeks later. An extra week of therapy (6 mg/kg/day) can be administered if clinically indicated at that time. A once-weekly regimen may also be effective. When ectothrix organisms (e.g., Microsporum canis) are present, a longer duration of therapy may be required. The data suggest that the newer agents are effective, safe with few adverse effects, and have a high benefit:risk ratio. It remains to be seen to what extent griseofulvin will be superseded for the treatment of tinea capitis. Adjunctive therapies may help decrease the risk of infection to other individuals. Appropriate measures should be taken to reduce the possibility of reinfection.