How Much Human Ringworm Is Zoophilic? Mcphee A, Cherian S, Robson J Adapted from Poster Produced for the Zoonoses Conference 25–26 July 2014 Brisbane
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How much human ringworm is zoophilic? McPhee A, Cherian S, Robson J Adapted from poster produced for the Zoonoses Conference 25–26 July 2014 Brisbane Introduction Epidermophyton floccosum Humans Common Dermatophytes can be the cause of common infections in both Trichophyton rubrum [worldwide] Humans Very common humans and animals. The source of human infection may be Trichophyton rubrum [African] Humans Less common anthropophilic (human), geophilic (soil) or zoophilic (animal). Trichophyton interdigitale Anthropophilic Humans Common Zoophilic dermatophyte infections usually elicit a strong host [anthropophilic] response on the skin where there is contact with the infective Trichophyton tonsurans Humans Common animal or contaminated fomites. Table 1 illustrates the range of Trichophyton violaceum Humans Less common dermatophytes that are isolated from the mycology laboratory Microsporum audouinii Humans Less common and grouped by source of acquisition. Microsporum gypseum Soil Common Geophilic Microsporum nanum Soil/Pigs Rare Guinea pigs, Aim Trichophyton interdigitale [zoophilic] Common kangaroos To characterize and compare zoophilic with non-zoophilic Microsporum canis Cats Common dermatophyte human infections isolated at Sullivan Nicolaides Zoophilic Trichophyton verrucosum Cattle Rare Pathology (SNP) for the year 2013. Trichophyton equinum Horses Rare Microsporum nanum Soil/pigs Rare Method Table 1: Classification of dermatophytes according to source Superficial fungal cultures submitted in 2013 to Sullivan Nicolaides Pathology were reviewed. This laboratory services Queensland and extends into New South Wales as far south as Coffs Harbour. Specimens include skin scrapings, skin biopsies, nails and involved hair. All cutaneous samples (Figure 1) submitted for fungal culture receive direct examination using Calcofluor white/Evans Blue/ KOH/Glycerol under fluorescent and/or light microscopy (Figure 2) and cultured. Media used is Sabouraud and Dermatophyte Test Medium with antibiotics and antifungals and incubated for 21-28 days at 28˚C. Where necessary further Figure 1: Trichophyton interdigitale [zoophilic] infection on Kangaroo handler identification media is inoculated. Photo image courtesy Dr Chester Wilson Results In total 21,714 specimens were cultured for dermatophytes. 2,458 (11.3%) dermatophytes were cultured from 2,432 patients. Zoophilic dermatophytes accounted for 7.4% of the total with equal numbers of Microsporum canis and Trichophyton interdigitale [zoophilic]. In only one patient was T. verrucosum cultured (Table 2). Younger age groups were more likely to have a zoophilic fungus isolated (Table 2). After Trichophyton tonsurans, Microsporum canis was the most common Figure 2: Hyphae (fluorescence) Figure 3: Ectothrix hair infection is characteristic cause of scalp infection particularly in younger age groups of zoophilic dermatophytes (Table 2, 3). Trichophyton interdigitale [zoophilic], formerly T. mentagrophytes, on the other hand was a rare cause of scalp infection, mainly affecting the skin (Figure 1 and Table 3). No zoophilic fungi resulted in significant numbers of nail infections (Table 3). Microscopy was positive in just over three quarters of samples submitted. For scalp infections ectothrix (Figure 3) was the norm for M.canis (Figure 4,5). The single case of T. verrucosum was a 29 year old male who worked with cattle. Figure 4: Culture of M. canis (Sabouraud) Figure 5: Spindle macroconidia - M. canis Age Group (years) 0-4 5-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 ≥80 Dermatophyte n % n % n % n % n % n % n % n % n % n % TOTAL Trichophyton interdigitale 1 1 1 1 14 7 19 9 25 10 76 21 89 25 133 32 97 30 58 37 513 Trichophyton rubrum [worldwide] 6 8 12 9 82 40 145 67 190 78 219 61 233 65 254 77 213 67 91 58 1445 Trichophytonviolaceum 2 3 6 5 2 1 1 0 1 0 0 1 0 1 0 0 0 14 Trichophyton rubrum [African] 1 1 3 2 1 0 0 1 0 0 0 0 0 0 6 Trichophyton tonsurans 27 35 41 31 34 17 7 3 2 1 6 2 1 0 3 1 0 0 1 1 122 Microsporum audouinii 2 3 1 1 0 0 0 0 0 0 0 0 3 Epidermophyton floccosum 0 0 1 1 15 7 8 4 5 2 10 3 10 3 9 2 6 2 4 3 68 Microsporum gypseum 14 18 13 10 17 8 6 3 8 3 12 3 16 4 10 2 4 1 2 1 102 Trichophyton interdigitale [zoophilic] 12 15 19 15 20 10 17 8 7 3 3 1 6 2 7 2 1 0 0 0 92 Trichophyton verrucosum 0 0 0 1 0 0 0 0 0 0 0 1 Microsporum canis 13 17 34 26 19 9 11 5 4 2 4 1 3 1 3 1 0 0 1 1 92 TOTAL 78 100 131 100 204 100 215 100 243 100 330 92 359 100 420 100 321 100 157 100 2458 Table 2: Dermatophytes isolated by age and source SNP 2013. Top 3 by age Nail Scalp Skin Total 60 Dermatophyte n % n % n % n % 50 Trichophyton interdigitale 323 33.0 190 14.1 513 20.9 40 Trichophyton rubrum [worldwide] 630 64.3 4 3.2 811 60.0 1445 58.8 30 Trichophyton violaceum 8 6.3 6 0.4 14 0.6 Trichophyton rubrum [African] (syn 20 5 4.0 1 0.1 6 0.2 T.soudanense) 10 Trichophyton tonsurans 3 0.3 59 46.8 60 4.4 122 5.0 0 Microsporum audouinii 3 2.4 3 0.1 Epidermophyton floccosum 8 0.8 60 4.4 68 2.8 Microsporum gypseum 15 1.5 8 6.3 79 5.8 102 4.1 Trichophyton interdigitale[zoophilic] 2 1.6 90 6.7 92 3.7 (syn T.mentagrophytes) Trichophyton verrucosum 1 0.1 1 0.0 Microsporum canis 1 0.1 37 29.4 54 4.0 92 3.7 TOTAL 980 100 126 100 1352 100 2458 100 Figure 6: Scalp infections by dermatophyte type Table 3: Dermatophytes isolated by site and source SNP 2013. Top 3 by site Conclusion Zoophilic dermatophytes comprise 7.4% of all dermatopytes grown They tend to cause infections in younger children and scalp infections are over represented (Figure 6). Further information Dr Jenny Robson E: [email protected] P: (07) 3377 8560 Dr Sarah Cherian E: [email protected] P: (07) 3377 8628 Ann McPhee E: [email protected] P: (07) 3377 8536 SULLIVAN NICOLAIDES PTY LTD • ABN 38 078 202 196 A subsidiary of Sonic Healthcare Limited • ABN 24 004 196 909 24 Hurworth Streed • Bowen Hills • QLD 4006 • Australia Tel (07) 3377 8666 • Fax (07) 3870 0549 P O Box 2014 • Fortitude Valley • Qld 4006 • Australia Meridio 189687 September 2016 www.snp.com.au © Sullivan Nicolaides Pty Ltd 2016.